JP2008099669A - Method for producing recombinant protein as soluble protein - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To produce an objective protein as a soluble protein by using a recombinant protein-expressing system. <P>SOLUTION: The expression vector contains (1) an expression inducible promotor sequence, (2) a first encoding sequence containing a polynucleotide encoding a polypeptide expressed by a specific amino acid sequence and (3) a second encoding sequence containing a polynucleotide encoding the objective protein. The method for producing the objective protein comprises the expression of the protein by using the expression vector. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a target protein as a soluble protein.

So far, many recombinant protein expression systems such as recombinant protein expression systems and cell-free translation systems in hosts such as bacteria, yeast, insects, transgenic animals and transgenic plants have been developed. Among these, Escherichia coli is easy to grow at a high density, and since research on host vector systems has been advanced, it is widely used as an expression system for heterologous proteins.
On the other hand, when the target protein is expressed in these recombinant protein expression systems, the expressed protein cannot be folded correctly, so that the original function of the protein cannot be expressed, or insoluble aggregates called inclusion bodies are formed. Often formed. In such a case, for example, even if the inclusion body is solubilized with a denaturant, a surfactant, or the like and then refolded, a protein that is normally folded and has the original function is not necessarily obtained. Moreover, even if a protein that expresses the original function is obtained, a satisfactory recovery rate is often not obtained.
Under such circumstances, a method for suppressing the formation of inclusion bodies of the expressed recombinant target protein has not been established so far. As an alternative, an attempt has been made to express a soluble protein by fusing a highly soluble maltose-binding protein having a molecular weight of 40,000 or glutathione S-transferase (GST) and an insoluble target protein (Non-patent Document 1: Fox, JDand Waugh, DS (2003) Maltose-binding protein as a solubility enhancer. Methods Mol. Biol. 205: 99-117, Non-Patent Document 2: Ausubel, FM et al. Eds. (1996) Current Protocols in Molecular Biology , Vol. 2, 16.0.1). However, there are problems that the soluble protein does not exhibit the original activity or function, and that when the maltose binding protein or GST is deleted, the target protein is insolubilized.

The ZZ domain is a synthetic IgG binding region developed based on the IgG binding region of protein A (for example, Non-Patent Document 3: Nilsson B. et al., Protein Eng. (1987) 1: 107-113). reference).
However, when the ZZ domain of the IgG binding region is fused and expressed with the target protein, there is no report on the effect of increasing the solubility of the fusion protein and the effect involved in the efficient refolding of the target protein to the active protein. To date, the ZZ domain derived from protein A has only been used as a ligand in IgG antibody affinity chromatography in purifying the target protein after expressing the target protein and the fusion protein. Furthermore, IgG antibody columns are expensive, and there are limited cases where they can be used when mass-producing and utilizing genetically engineered fusion proteins using ZZ domains.

Fox, JDand Waugh, DS (2003) Maltose-binding protein as a solubility enhancer. Methods Mol. Biol. 205: 99-117 Ausubel, FM et al. Eds. (1996) Current Protocols in Molecular Biology, Vol. 2, 16.0.1 Nilsson B. et al., Protein Eng. (1987) 1: 107-113

  In the above situation, it is strongly desired industrially to produce a target protein as a soluble protein using a recombinant protein expression system for the production of useful proteins. There is also a strong demand in research fields such as research on the function and structure of proteins.

As a result of intensive studies to solve the above problems, the present inventors have
(1) a promoter sequence that can induce expression;
(2) a first coding sequence containing a polynucleotide encoding a ZZ domain; and (3) expressing the target protein using an expression vector containing a second coding sequence containing a polynucleotide encoding the target protein. And the target protein was found to be expressed as a soluble protein. As a result of further studies based on these findings, the present invention has been completed.

That is, the present invention
(1) (1) a promoter sequence capable of inducing expression;
(2) Formula (Z) _n
(In the formula, n represents an integer of 1 to 5, and Z represents a polypeptide selected from the group consisting of the following (a) to (d):
(A) a polypeptide comprising the amino acid sequence of SEQ ID NO: 1,
(B) a polypeptide comprising an amino acid sequence in which one or more amino acids are deleted, substituted, inserted and / or added in the amino acid sequence of SEQ ID NO: 1;
(C) a polypeptide comprising an amino acid sequence having 90% or more identity to the amino acid sequence of SEQ ID NO: 1, and (d) a polynucleotide comprising a base sequence complementary to the base sequence of SEQ ID NO: 2. A polypeptide comprising an amino acid sequence encoded by a polynucleotide that hybridizes under stringent conditions)
And a first coding sequence comprising a polynucleotide that encodes a polypeptide having a function of allowing the fusion protein to be expressed as a soluble protein when expressed as a fusion protein with the target protein; 3) an expression vector containing a second coding sequence containing a polynucleotide encoding the protein of interest,
(2) The vector according to (1) above, wherein the polypeptide represented by the formula (Z) _n is a polypeptide represented by (Z) ₂ .
(3) The polypeptide represented by the formula (Z) ₂ is
(E) a polypeptide consisting of the amino acid sequence of SEQ ID NO: 3,
(F) When the amino acid sequence of SEQ ID NO: 3 comprises an amino acid sequence in which one or more amino acids are deleted, substituted, inserted and / or added, and is expressed as a fusion protein with the target protein, A polypeptide having a function capable of expressing a fusion protein as a soluble protein,
(G) When the amino acid sequence has an amino acid sequence having 90% or more identity to the amino acid sequence of SEQ ID NO: 3 and is expressed as a fusion protein with the target protein, the fusion protein is expressed as a soluble protein. And (h) an amino acid sequence encoded by a polynucleotide that hybridizes under stringent conditions with a polynucleotide consisting of a base sequence complementary to the base sequence of SEQ ID NO: 4, and The vector according to (2) above, which is a polypeptide selected from the group consisting of polypeptides having a function capable of being expressed as a soluble protein when expressed as a fusion protein with a target protein,
(4) The vector according to any one of (1) to (3) above, wherein the promoter sequence capable of inducing expression is a promoter sequence capable of inducing expression at low temperature,
(5) The vector according to (4) above, wherein the promoter sequence capable of inducing expression at a low temperature is a cold shock gene promoter sequence,
(6) The vector according to (5) above, wherein the promoter sequence of the cold shock gene is a promoter sequence of an E. coli cold shock gene,
(7) The vector according to (6) above, wherein the promoter sequence of the E. coli cold shock gene is the promoter sequence of the E. coli cold shock gene cspA, cspB, cspG, cspI or csdA.
(8) The above (1) to (7), further comprising a coding sequence containing a polynucleotide encoding a cleavable linker peptide between the first coding sequence and the second coding sequence. A vector according to any one of
(9) The vector according to (8) above, wherein the cleavable linker peptide is a linker peptide having a protease cleavage site,
(10) The coding sequence according to any one of (1) to (9) above, further comprising a coding sequence containing a polynucleotide encoding an amino acid sequence for purification on the 5 ′ side of the first coding sequence. vector,
(11) The vector according to (10) above, wherein the amino acid sequence for purification is a histidine tag sequence,
(12) (1) a promoter sequence capable of inducing expression;
(2) Formula (Z) _n
(In the formula, n represents an integer of 1 to 5, and Z represents a polypeptide selected from the group consisting of the following (a) to (d):
(A) a polypeptide comprising the amino acid sequence of SEQ ID NO: 1,
(B) a polypeptide comprising an amino acid sequence in which one or more amino acids are deleted, substituted, inserted and / or added in the amino acid sequence of SEQ ID NO: 1;
(C) a polypeptide comprising an amino acid sequence having 90% or more identity to the amino acid sequence of SEQ ID NO: 1, and (d) a polynucleotide comprising a base sequence complementary to the base sequence of SEQ ID NO: 2. A polypeptide comprising an amino acid sequence encoded by a polynucleotide that hybridizes under stringent conditions)
And a first coding sequence comprising a polynucleotide that encodes a polypeptide having a function of allowing the fusion protein to be expressed as a soluble protein when expressed as a fusion protein with the target protein; 3) an expression vector containing at least one restriction enzyme site into which a second coding sequence containing a polynucleotide encoding the protein of interest can be inserted;
(13) The vector according to (12) above, wherein the polypeptide represented by the formula (Z) _n is a polypeptide represented by (Z) ₂ .
(14) The polypeptide represented by the formula (Z) ₂ is:
(E) a polypeptide consisting of the amino acid sequence of SEQ ID NO: 3,
(F) When the amino acid sequence of SEQ ID NO: 3 comprises an amino acid sequence in which one or more amino acids are deleted, substituted, inserted and / or added, and is expressed as a fusion protein with the target protein, A polypeptide having a function capable of expressing a fusion protein as a soluble protein,
(G) When the amino acid sequence has an amino acid sequence having 90% or more identity to the amino acid sequence of SEQ ID NO: 3 and is expressed as a fusion protein with the target protein, the fusion protein is expressed as a soluble protein. And (h) an amino acid sequence encoded by a polynucleotide that hybridizes under stringent conditions with a polynucleotide consisting of a base sequence complementary to the base sequence of SEQ ID NO: 4, and The vector according to (13) above, which is a polypeptide selected from the group consisting of polypeptides having a function capable of being expressed as a soluble protein when expressed as a fusion protein with a target protein,
(15) The vector according to any one of (12) to (14) above, wherein the promoter sequence capable of inducing expression is a promoter sequence capable of inducing expression at low temperature,
(16) The vector according to (15) above, wherein the promoter sequence capable of inducing expression at a low temperature is a cold shock gene promoter sequence,
(17) The vector according to (16) above, wherein the cold shock gene promoter sequence is an E. coli cold shock gene promoter sequence,
(18) The vector according to (17), wherein the promoter sequence of the E. coli cold shock gene is the promoter sequence of the E. coli cold shock gene cspA, cspB, cspG, cspI or csdA.
(19) The above (12) to (18), further comprising a coding sequence containing a polynucleotide encoding a cleavable linker peptide between the first coding sequence and the second coding sequence. A vector according to any one of
(20) The vector according to (19) above, wherein the cleavable linker peptide is a linker peptide having a protease cleavage site,
(21) The coding sequence according to any one of (12) to (20), further comprising a coding sequence containing a polynucleotide encoding an amino acid sequence for purification on the 5 ′ side of the first coding sequence. vector,
(22) The vector according to (21) above, wherein the amino acid sequence for purification is a histidine tag sequence,
(23) (1) Formula (Z) _n
(In the formula, n represents an integer of 1 to 5, and Z represents a polypeptide selected from the group consisting of the following (a) to (d):
(A) a polypeptide comprising the amino acid sequence of SEQ ID NO: 1,
(B) a polypeptide comprising an amino acid sequence in which one or more amino acids are deleted, substituted, inserted and / or added in the amino acid sequence of SEQ ID NO: 1;
(C) a polypeptide comprising an amino acid sequence having 90% or more identity to the amino acid sequence of SEQ ID NO: 1, and (d) a polynucleotide comprising a base sequence complementary to the base sequence of SEQ ID NO: 2. A polypeptide comprising an amino acid sequence encoded by a polynucleotide that hybridizes under stringent conditions)
And a first amino acid sequence containing an amino acid sequence of a polypeptide having a function capable of being expressed as a soluble protein when expressed as a fusion protein with a target protein; and (2) A fusion protein containing a second amino acid sequence containing the amino acid sequence of the target protein and capable of being expressed as a soluble protein;
(24) The fusion protein according to (23), wherein the polypeptide represented by the formula (Z) _n is a polypeptide represented by (Z) ₂ .
(25) The polypeptide represented by the formula (Z) ₂ is:
(E) a polypeptide consisting of the amino acid sequence of SEQ ID NO: 3,
(F) When the amino acid sequence of SEQ ID NO: 3 comprises an amino acid sequence in which one or more amino acids are deleted, substituted, inserted and / or added, and is expressed as a fusion protein with the target protein, A polypeptide having a function capable of expressing a fusion protein as a soluble protein,
(G) When the amino acid sequence has an amino acid sequence having 90% or more identity to the amino acid sequence of SEQ ID NO: 3 and is expressed as a fusion protein with the target protein, the fusion protein is expressed as a soluble protein. And (h) an amino acid sequence encoded by a polynucleotide that hybridizes under stringent conditions with a polynucleotide consisting of a base sequence complementary to the base sequence of SEQ ID NO: 4, and The fusion protein according to (24) above, which is a polypeptide selected from the group consisting of polypeptides having a function capable of being expressed as a soluble protein when expressed as a fusion protein with a target protein,
(26) The fusion protein according to any one of (23) to (25), wherein the target protein is any one selected from the group consisting of apoaequorin, Gaussia luciferase, and ebyl luciferase,
(27) Any of the above (23) to (26), further comprising an amino acid sequence containing a cleavable linker peptide amino acid sequence between the first amino acid sequence and the second amino acid sequence A fusion protein according to claim 1,
(28) The fusion protein according to (27), wherein the cleavable linker peptide is a linker peptide having a protease cleavage site,
(29) The fusion protein according to any one of (23) to (28), further comprising an amino acid sequence for purification on the amino terminal side of the first amino acid sequence,
(30) The fusion protein according to (29), wherein the amino acid sequence for purification is a histidine tag sequence,
(31) Formula (Z) _n- L-X
(Wherein n represents an integer of 1 to 5; L represents a cleavable linker peptide; Z represents a polypeptide selected from the group consisting of the following (a) to (d):
(A) a polypeptide comprising the amino acid sequence of SEQ ID NO: 1,
(B) a polypeptide comprising an amino acid sequence in which one or more amino acids are deleted, substituted, inserted and / or added in the amino acid sequence of SEQ ID NO: 1;
(C) a polypeptide comprising an amino acid sequence having 90% or more identity to the amino acid sequence of SEQ ID NO: 1, and (d) a polynucleotide comprising a base sequence complementary to the base sequence of SEQ ID NO: 2. A polypeptide comprising an amino acid sequence encoded by a polynucleotide that hybridizes under stringent conditions; X represents the amino acid sequence of the target protein)
A fusion protein that can be expressed as a soluble protein,
(32) The fusion protein according to (31) above, wherein the target protein is any one selected from the group consisting of apoaequorin, Gaussia luciferase and ebyl luciferase.
(33) a polynucleotide containing a polynucleotide encoding the fusion protein according to any one of (23) to (32),
(34) The polynucleotide according to (33), which is DNA,
(35) (1) a promoter sequence capable of inducing expression;
(2) Formula (Z) _n
(In the formula, n represents an integer of 1 to 5, and Z represents a polypeptide selected from the group consisting of the following (a) to (d):
(A) a polypeptide comprising the amino acid sequence of SEQ ID NO: 1,
(B) a polypeptide comprising an amino acid sequence in which one or more amino acids are deleted, substituted, inserted and / or added in the amino acid sequence of SEQ ID NO: 1;
(C) a polypeptide comprising an amino acid sequence having 90% or more identity to the amino acid sequence of SEQ ID NO: 1, and (d) a polynucleotide comprising a base sequence complementary to the base sequence of SEQ ID NO: 2. A polypeptide comprising an amino acid sequence encoded by a polynucleotide that hybridizes under stringent conditions)
And a first coding sequence comprising a polynucleotide that encodes a polypeptide having a function of allowing the fusion protein to be expressed as a soluble protein when expressed as a fusion protein with the target protein; 3) A method for producing the target protein as a soluble protein, comprising expressing the protein using an expression vector containing a second coding sequence containing a polynucleotide encoding the target protein,
(36) The method according to (35) above, wherein the polypeptide represented by the formula (Z) _n is a polypeptide represented by (Z) ₂ .
(37) The polypeptide represented by the formula (Z) ₂ is:
(E) a polypeptide consisting of the amino acid sequence of SEQ ID NO: 3,
(F) When the amino acid sequence of SEQ ID NO: 3 comprises an amino acid sequence in which one or more amino acids are deleted, substituted, inserted and / or added, and is expressed as a fusion protein with the target protein, A polypeptide having a function capable of expressing a fusion protein as a soluble protein,
(G) When the amino acid sequence has an amino acid sequence having 90% or more identity to the amino acid sequence of SEQ ID NO: 3 and is expressed as a fusion protein with the target protein, the fusion protein is expressed as a soluble protein. And (h) an amino acid sequence encoded by a polynucleotide that hybridizes under stringent conditions with a polynucleotide consisting of a base sequence complementary to the base sequence of SEQ ID NO: 4, and The method according to (36) above, wherein when expressed as a fusion protein with a target protein, the fusion protein is a polypeptide selected from the group consisting of polypeptides having a function capable of being expressed as a soluble protein.
(38) The method according to any one of (35) to (37) above, wherein the promoter sequence capable of inducing expression is a promoter sequence capable of inducing expression at a low temperature.
(39) The method according to (38) above, wherein the promoter sequence capable of inducing expression at a low temperature is a cold shock gene promoter sequence,
(40) The method according to (39) above, wherein the cold shock gene promoter sequence is an E. coli cold shock gene promoter sequence,
(41) The method according to (40) above, wherein the promoter sequence of the E. coli cold shock gene is the promoter sequence of the E. coli cold shock gene cspA, cspB, cspG, cspI or csdA.
(42) The above (35) to (41), further comprising a coding sequence containing a polynucleotide encoding a cleavable linker peptide between the first coding sequence and the second coding sequence. A method according to any of the above,
(43) The method according to (42), wherein the cleavable linker peptide is a linker peptide having a protease cleavage site,
(44) The method according to any one of (35) to (43), further comprising a coding sequence containing a polynucleotide encoding an amino acid sequence for purification on the 5 ′ side of the first coding sequence. Method,
(45) The method according to (44) above, wherein the amino acid sequence for purification is a histidine tag sequence.

According to the present invention, when a target protein is produced using a recombinant protein expression system, the target protein can be produced as a soluble protein, so that it is not necessary to denature (solubilize) the target protein. Therefore, according to the present invention, the target protein can be obtained efficiently and at a high recovery rate.
Therefore, the present invention is extremely useful as a method for producing useful proteins and proteins such as proteins to be analyzed for functions and structures.

The present invention includes (1) a first amino acid sequence containing the amino acid sequence of the polypeptide represented by formula (Z) _n , and (2) a second amino acid sequence containing the amino acid sequence of the target protein. There are provided a fusion protein, a polynucleotide encoding the fusion protein, a method for producing the fusion protein using the polynucleotide, and the like.
The present invention also provides (1) a promoter sequence capable of inducing expression,
(2) a first coding sequence containing a polynucleotide encoding the polypeptide represented by formula (Z) _n , and (3) a second coding sequence containing a polynucleotide encoding the protein of interest. An expression vector, a method for producing the target protein including expression of a protein using the expression vector, and the like are also provided. According to the production method, the target protein can be produced in a solubilized state.
Hereinafter, the present invention will be described in detail.

1. Fusion protein of the present invention The fusion protein of the present invention comprises:
(1) A first amino acid sequence containing the amino acid sequence of the polypeptide represented by formula (Z) _n , and (2) a second amino acid sequence containing the amino acid sequence of the target protein.
Furthermore, the fusion protein of the present invention comprises
(3) An amino acid sequence containing the amino acid sequence of a cleavable peptide linker may be included.
Hereinafter, the fusion protein of the present invention will be described in more detail.

(1) (Z) polypeptide expression represented by _n (Z) polypeptide represented by _n, when expressed as a fusion protein with the target protein, the fusion protein can be expressed as a soluble protein Has activity or function.
Z represents a polypeptide selected from the group consisting of the following (a) to (d):
(A) a polypeptide comprising the amino acid sequence of SEQ ID NO: 1,
(B) a polypeptide comprising an amino acid sequence in which one or more amino acids are deleted, substituted, inserted and / or added in the amino acid sequence of SEQ ID NO: 1;
(C) a polypeptide comprising an amino acid sequence having 90% or more identity to the amino acid sequence of SEQ ID NO: 1, and (d) a polynucleotide comprising a base sequence complementary to the base sequence of SEQ ID NO: 2. A polypeptide comprising an amino acid sequence encoded by a polynucleotide that hybridizes under stringent conditions.

  In the present specification, the range of “1 to plural” in “an amino acid sequence in which one or more amino acids are deleted, substituted, inserted and / or added” is, for example, 1 to 20, 1 to 15, 1 to 10, 1 to 9, 1 to 8, 1 to 7, 1 to 6 (1 to several), 1 to 5, 1 to 4, 1 to 3, 1 to 2 One. In general, the smaller the number of amino acids deleted, substituted, inserted or added, the better. Two or more of the amino acid residue deletions, substitutions, insertions and additions may occur simultaneously. Such regions are described in “Molecular Cloning 3rd Edition”, “Current Protocols in Molecular Biology”, “Nuc. Acids. Res., 10, 6487 (1982)”, “Proc. Natl. Acad. Sci. USA, 79, 6409 (1982) ”,“ Gene, 34, 315 (1985) ”,“ Nuc. Acids. Res., 13, 4431 (1985) ”,“ Proc. Natl. Acad. Sci. USA , 82, 488 (1985) ”and the like.

  In addition, the range of “90% or more” in “polypeptide consisting of an amino acid sequence having 90% or more identity” is, for example, 90% or more, 91% or more, 92% or more, 93% or more, 94% or more, 95% or more, 96% or more, 97% or more, 98% or more, 99% or more, 99.1% or more, 99.2% or more, 99.3% or more, 99.4% or more, 99.5% or more, They are 99.6% or more, 99.7% or more, 99.8% or more, 99.9% or more. In general, the larger the numerical value of identity, the better. The identity of amino acid sequences and base sequences is determined by BLAST (see, for example, Altzshul SF et al., J. Mol. Biol. 215, 403 (1990)) or FASTA (Pearson WR, Methods in Enzymology 183, 63 (See (1990), etc.). When using BLAST or FASTA, the default parameters of each program are used.

  The polynucleotide that hybridizes under stringent conditions will be described later.

n represents an integer of 1 to 5, preferably 2 or 3, and particularly preferably 2.
Formula (Z) In the polypeptide represented by _n , each Z may be the same or different.
As the polypeptide represented by the formula (Z) _n , a polypeptide represented by the formula (Z) ₂ is particularly preferable.

The polypeptide represented by the formula (Z) ₂ has, for example, substantially the same activity or function as the polypeptide consisting of the amino acid sequence of SEQ ID NO: 3 or the polypeptide consisting of the amino acid sequence of SEQ ID NO: 3. A polypeptide. In the present specification, a polypeptide consisting of the amino acid sequence of SEQ ID NO: 3 or a polypeptide having substantially the same activity or function as the polypeptide consisting of the amino acid sequence of SEQ ID NO: 3 is referred to as a “ZZ domain”. is there.
The “substantially the same quality of activity or function” means, for example, an activity or function that allows the fusion protein to be expressed as a soluble protein when expressed as a fusion protein with the target protein. Such activity or function, for example, the IgG binding ability of the ZZ domain can be measured by a binding assay with IgG.

More specifically, examples of the polypeptide represented by the formula (Z) ₂ include:
(E) a polypeptide consisting of the amino acid sequence of SEQ ID NO: 3,
(F) When the amino acid sequence of SEQ ID NO: 3 comprises an amino acid sequence in which one or more amino acids are deleted, substituted, inserted and / or added, and is expressed as a fusion protein with the target protein, A polypeptide having an activity or function by which the fusion protein can be expressed as a soluble protein;
(G) When the amino acid sequence has an amino acid sequence having 90% or more identity to the amino acid sequence of SEQ ID NO: 3 and is expressed as a fusion protein with the target protein, the fusion protein is expressed as a soluble protein. And (h) an amino acid sequence encoded by a polynucleotide that hybridizes under stringent conditions with a polynucleotide consisting of a base sequence complementary to the base sequence of SEQ ID NO: 4. And a polypeptide selected from the group consisting of polypeptides having an activity or function that can be expressed as a soluble protein when expressed as a fusion protein with the target protein.

(2) Target protein There is no restriction | limiting in particular in the target protein in the fusion protein of this invention. For example, proteins that easily form inclusion bodies when expressed in a recombinant protein expression system can be preferably used.
Examples of the target protein of the present invention include coat protein, core protein, protease, reverse transcriptase, integrase encoded by pathogenic virus genomes such as hepatitis B virus, hepatitis C virus, HIV, influenza, etc. Protein (virus antigen); antibody Fab, (Fab) ₂ ; platelet derived growth factor (PDGF), stem cell growth factor (SCF), hepatocyte growth factor (HGF), transforming growth factor (TGF), nerve growth factor (NGF), epidermal growth factor (EGF), fibroblast growth factor (FGF), growth factor such as insulin-like growth factor (IGF); tumor necrosis factor, cytokines such as interferon, interleukin; erythropoietin, granulocyte Colony stimulating factor, granulocyte macrophage colony stimulation Hematopoietic factors such as litter, macrophage colony stimulating factor, thrombopoietin; luteinizing hormone releasing hormone (LH-RH), thyroid stimulating hormone releasing hormone (TRH), insulin, somatostatin, growth hormone, prolactin, corticotropin (ACTH), Melanocyte Stimulating Hormone (MSH), Thyroid Stimulating Hormone (TSH), Luteinizing Hormone (LH), Follicle Stimulating Hormone (FSH), Vasopressin, Oxytocin, Calcitonin, Parathyroid Hormone (PTH), Glucagon, Gastrin, Secretin, Pancreosai Peptide hormones such as min, cholecystokinin, angiotensin, human placental lactogen, human chorionic gonadotropin (HCG), cerulein, motilin; enkephalin, endorphin, di Analgesic peptides such as rufin and kyotorphin; enzymes such as superoxide dismutase (SOD), urokinase, tissue plasminogen activator (TPA), asparaginase and kallikrein; peptides such as bombesin, neurotensin, bradykinin and substance P Examples include, but are not limited to, sex neurotransmitters; albumin; collagen; proinsulin; renin; α1 antitrypsin.

  The target protein may be an apoprotein, that is, the protein portion of a holoprotein. Examples of the apoprotein include apoRLBP (see FEBS Lett. 268, 287-290 (1990), etc.), apoaequorin (see Proc. Natl. Acad. Sci. USA 82, 3154-3158 (1985), etc.), apocritin (See FEBS Lett. 315, 343-346 (1993), etc.), Apomytrocomin (see FEBS Lett. 333, 301-305 (1993), etc.), Apooverin (See Gene 153,273-274 (1995), etc.) Can be mentioned. The amino acid sequence of apoaequorin is shown in SEQ ID NO: 21.

  Further, the target protein may be a 19 kDa protein (KAZ) which is a catalytic unit of Gaussia luciferase (hGL) and Evil luciferase (Oplophorus luciferase). The amino acid sequence of Gaussia luciferase (hGL) is shown in SEQ ID NO: 23. The amino acid sequence of 19 kDa protein (KAZ) which is a catalytic unit of Evil luciferase is shown in SEQ ID NO: 25.

  The target protein of the present invention includes mutants of the above proteins. Examples of such a mutant include a protein having an amino acid sequence in which one or a plurality of amino acids are deleted, substituted, inserted and / or added in the amino acid sequence of the protein, and having the same activity as the protein. Is also included. Examples of such a protein include 1 to 100, 1 to 90, 1 to 80, 1 to 70, 1 to 60, 1 to 50, and 1 to 40 in the amino acid sequence of the protein. , 1-30, 1-20, 1-10, 1-9, 1-8, 1-7, 1-6 (1 to several), 1-5, 1-4 A protein having an amino acid sequence in which 1 to 3, 1 to 2, 1 or 2 amino acid residues are deleted, substituted, inserted and / or added, and having the same activity as the protein. In general, the smaller the number of amino acid residue deletions, substitutions, insertions and / or additions, the better. Two or more of deletion, substitution, insertion and addition may occur simultaneously.

The target protein of the present invention includes “partial peptides” of the above proteins. Examples of the partial peptide of the protein include a partial peptide consisting of a part of the amino acid sequence of the protein, and preferably have the same activity as that of the protein. Examples of such a partial peptide include a polypeptide having an amino acid sequence consisting of at least 20, preferably at least 50 amino acid residues in the amino acid sequence of the above protein. Preferably, these polypeptides contain an amino acid sequence corresponding to the portion involved in the activity of the protein. Moreover, the partial peptide used in the present invention is one or more (for example, about 1 to 20, more preferably about 1 to 10, more preferably 1 to 2) in the amino acid sequence of the above polypeptide. About 5 amino acid residues may be changed by deletion, addition, substitution, or insertion.
The partial peptide used in the present invention can also be used as an antigen for antibody production.

(3) A cleavable linker peptide, etc. The fusion protein of the present invention comprises a first amino acid sequence containing the amino acid sequence of the polypeptide represented by the formula (Z) _n and a first amino acid sequence containing the amino acid sequence of the target protein. An amino acid sequence containing an amino acid sequence of a cleavable linker peptide may be further included between the two amino acid sequences.
A cleavable linker peptide means a linker peptide having a cleavage site that can be cleaved by an enzymatic or chemical cleaving substance. Numerous peptides are known that are cleaved by enzymes (proteases) or chemicals (eg, Harlow and Lane, Antibodies: A Laboratory Manual, Cold Spring Harbor Laboratory Press, Cold Spring Harbor, NY (1988); Walsh, Proteins Biochemistry and Biotechnology, John Wiley & Sons, LTD., West Sussex, England (2002)). A cleaving substance is a chemical substance or enzyme that recognizes a cleavage site in a peptide and divides the peptide into two peptides by cleaving the bond in the peptide. Examples of the cleaving substance include chemical substances and proteases.
A preferred cleavable linker peptide in the present invention is a linker peptide having a protease cleavage site. Examples of protease cleavage sites include thrombin cleavage sites, human renovirus 3C protease cleavage sites, factor Xa and the like.
When the fusion protein of the present invention contains a cleavable linker peptide, the first amino acid sequence is removed from the fusion protein of the present invention by expressing the fusion protein of the present invention and then treating with a cleavage substance. Target protein can be obtained.

As the fusion protein of the present invention, specifically, for example,
Formula (Z) _n- L-X
(In the formula, L represents a linker peptide that can be directly bonded or cleaved, X represents the amino acid sequence of the target protein, and n and Z have the same meaning as described above.)
The fusion protein represented by is also mentioned.

  The fusion protein of the present invention may further contain an amino acid sequence for promoting translation and / or an amino acid sequence for purification. As an amino acid sequence for promoting translation, an amino acid sequence used in this technical field can be used. Examples of amino acid sequences for promoting translation include TEE sequences. As the amino acid sequence for purification, an amino acid sequence used in this technical field can be used. Examples of the amino acid sequence for purification include a histidine tag sequence having an amino acid sequence of 4 or more, preferably 6 or more histidine residues, and an amino acid sequence of a binding domain to glutathione of glutathione S-transferase Etc. The amino acid sequence for purification is preferably present on the amino terminal side of the first amino acid sequence.

2. Polynucleotide of the Present Invention The present invention also provides a polynucleotide encoding the above-described fusion protein of the present invention. The polynucleotide of the present invention may be any polynucleotide as long as it contains the base sequence encoding the fusion protein of the present invention, but is preferably DNA. Examples of DNA include genomic DNA, genomic DNA library, cell / tissue-derived cDNA, cell / tissue-derived cDNA library, and synthetic DNA. The vector used for the library is not particularly limited and may be any of bacteriophage, plasmid, cosmid, phagemid and the like. Moreover, it can also be amplified directly by reverse transcription polymerase chain reaction (hereinafter abbreviated as RT-PCR method) using a total RNA or mRNA fraction prepared from the cells / tissues described above.

As the polynucleotide of the present invention, specifically,
(1) A polynucleotide encoding a polypeptide represented by the formula (Z) _n and having an activity or function capable of being expressed as a soluble protein when expressed as a fusion protein with a target protein. A first coding sequence containing; and (2) a polynucleotide containing a second coding sequence containing a polynucleotide encoding the protein of interest, and the like.
Here, formula (Z) _n represents the same meaning as described above.

Among the polynucleotides of the present invention, among others,
(1) a first coding sequence containing a polynucleotide encoding a polypeptide represented by formula (Z) ₂ ; and (2) a second coding sequence containing a polynucleotide encoding a protein of interest. Polynucleotides are preferred.
Here, formula (Z) ₂ represents the same meaning as described above.

Examples of the polynucleotide encoding the polypeptide represented by the formula (Z) ₂ include a polynucleotide selected from the group consisting of the following (e) to (h):
(E) a polynucleotide containing a polynucleotide consisting of the base sequence of SEQ ID NO: 4,
(F) When hybridized with a polynucleotide comprising a base sequence complementary to the base sequence of SEQ ID NO: 4 under stringent conditions and expressed as a fusion protein with the target protein, the fusion protein is soluble A polynucleotide comprising a polynucleotide encoding a polypeptide having an activity or function capable of being expressed as a protein;
(G) a polynucleotide containing a polynucleotide encoding a polypeptide consisting of the amino acid sequence of SEQ ID NO: 3, and (h) one to a plurality of amino acids in the amino acid sequence of SEQ ID NO: 3 deleted, substituted, or inserted And / or a polynucleotide comprising a polynucleotide that encodes a polypeptide having an activity or function that can be expressed as a soluble protein when expressed as a fusion protein with a target protein. Examples include nucleotides.

As such a preferable polynucleotide of the present invention, for example,
(1) A first coding sequence selected from the group consisting of the following (e) to (h):
(E) a polynucleotide containing a polynucleotide consisting of the base sequence of SEQ ID NO: 4,
(F) When hybridized with a polynucleotide comprising a base sequence complementary to the base sequence of SEQ ID NO: 4 under stringent conditions and expressed as a fusion protein with the target protein, the fusion protein is soluble A polynucleotide comprising a polynucleotide encoding a polypeptide having an activity or function capable of being expressed as a protein;
(G) a polynucleotide containing a polynucleotide encoding a polypeptide consisting of the amino acid sequence of SEQ ID NO: 3, and (h) one to a plurality of amino acids are deleted, substituted, or inserted in the amino acid sequence of SEQ ID NO: 3. And / or a polynucleotide comprising a polynucleotide that encodes a polypeptide having an activity or function that can be expressed as a soluble protein when expressed as a fusion protein with a target protein. Nucleotides; and
(2) A polynucleotide containing a second coding sequence containing a polynucleotide encoding the target protein.

  Here, “a polynucleotide that hybridizes under stringent conditions (for example, DNA)” means a polynucleotide comprising a nucleotide sequence complementary to the nucleotide sequence of SEQ ID NO: 2 or 4, or SEQ ID NO: 1 or 3 A polynucleotide (for example, DNA) obtained by using a colony hybridization method, a plaque hybridization method, a Southern hybridization method, or the like using as a probe all or part of a polynucleotide encoding the amino acid sequence of Specifically, hybridization was performed at 65 ° C. in the presence of 0.7 to 1.0 mol / L NaCl using a filter on which a polynucleotide derived from colony or plaque was immobilized, and then 0.1 to 2 Wash the filter at 65 ° C using double-concentration SSC (Saline-sodium citrate) solution (composition of single-concentration SSC solution is 150 mmol / L sodium chloride, 15 mmol / L sodium citrate) Polynucleotides that can be identified by:

  Hybridization is described in Sambrook J. et al., Molecular Cloning: A Laboratory Manual, Third Edition, Cold Spring Harbor Laboratory Press (2001) (hereinafter abbreviated as Molecular Cloning 3rd Edition), Ausbel FM et al., Current Protocols. In experimental documents such as in Molecular Biology, Supplement 1-38, John Wiley and Sons (1987-1997), Glover DM and Hames BD, DNA Cloning 1: Core Techniques, A practical Approach, Second Edition, Oxford University Press (1995) It can be carried out according to the method described.

  As used herein, the “stringent conditions” may be any of low stringency conditions, moderate stringency conditions, and high stringency conditions. “Low stringent conditions” are, for example, conditions of 5 × SSC, 5 × Denhardt's solution, 0.5% (w / v) SDS, 50% (v / v) formamide, 32 ° C. The “medium stringent conditions” are, for example, conditions of 5 × SSC, 5 × Denhardt's solution, 0.5% (w / v) SDS, 50% (v / v) formamide, 42 ° C. “High stringent conditions” are, for example, conditions of 5 × SSC, 5 × Denhardt's solution, 0.5 (w / v)% SDS, 50% (v / v) formamide, 50 ° C. The tighter the conditions, the higher the complementarity required for duplex formation. Specifically, for example, it can be expected that a polynucleotide (eg, DNA) having high homology as the temperature is increased can be efficiently obtained under these conditions. However, multiple factors such as temperature, probe concentration, probe length, ionic strength, time, and salt concentration can be considered as factors that affect hybridization stringency. Those skilled in the art will select these factors as appropriate. It is possible to achieve similar stringency.

  In addition, when using a commercially available kit for hybridization, Alkphos Direct Labeling Reagents (made by Amersham Pharmacia) can be used, for example. In this case, follow the protocol attached to the kit, incubate with the labeled probe overnight, and then wash the membrane with a primary wash buffer containing 0.1% (w / v) SDS at 55 ° C. , Hybridized DNA can be detected.

  Other hybridizable polynucleotides are approximately 60% of the polynucleotide encoding the amino acid sequence of SEQ ID NO: 1 or 3 when calculated using FASTA, BLAST and other analysis programs using default parameters. Over 65%, over 70%, over 75%, over 80%, over 85%, over 88%, over 90%, over 92%, over 95%, over 97%, over 98%, over 99%, DNA having the identity of 99.3% or more, 99.5% or more, 99.7% or more, 99.8% or more, 99.9% or more can be mentioned. The identity of amino acid sequences and base sequences can be determined using the method described above.

  A polynucleotide encoding a region having an amino acid sequence in which one or a plurality of amino acids are deleted, substituted, inserted and / or added to a certain amino acid sequence can be obtained by site-directed mutagenesis (see, eg, Gotoh, T. et al., Gene 152, 271-275 (1995), Zoller, MJ, and Smith, M., Methods Enzymol. 100, 468-500 (1983), Kramer, W. et al., Nucleic Acids Res. 12, 9441-9456 (1984), Kramer W, and Fritz HJ, Methods.Enzymol. 154, 350-367 (1987), Kunkel, TA, Proc. Natl. Acad. Sci. USA. 82, 488-492 (1985), Kunkel, Methods Enzymol. 85, 2763-2766 (1988), etc.), methods using amber mutation (for example, see Gapped duplex method, Nucleic Acids Res. 12, 9441-9456 (1984), etc.) Can be obtained.

  PCR (for example, Ho SN et al., Gene 77, 51 (for example, Ho SN et al., Gene 77, 51 ( 1989), etc.) can also introduce mutations into polynucleotides.

  A polynucleotide encoding a partial fragment of a protein that is a kind of deletion mutant has a sequence that matches the 5'-end base sequence of the region encoding the partial fragment to be produced in the polynucleotide encoding the protein. It can be obtained by performing PCR using an oligonucleotide and an oligonucleotide having a sequence complementary to the base sequence at the 3 ′ end as a primer and using a polynucleotide encoding the protein as a template.

  Specific examples of the polynucleotide of the present invention include a polynucleotide encoding a fusion protein consisting of the amino acid sequence of SEQ ID NO: 7, SEQ ID NO: 11, SEQ ID NO: 15, SEQ ID NO: 17 or SEQ ID NO: 19. Examples thereof include a polynucleotide. Examples of the polynucleotide containing a polynucleotide encoding a fusion protein consisting of the amino acid sequence set forth in SEQ ID NO: 7 include a polynucleotide containing a polynucleotide consisting of the base sequence set forth in SEQ ID NO: 8. . Examples of the polynucleotide containing a polynucleotide encoding a fusion protein consisting of the amino acid sequence set forth in SEQ ID NO: 11 include a polynucleotide containing a polynucleotide consisting of the base sequence set forth in SEQ ID NO: 12. . Examples of the polynucleotide containing a polynucleotide encoding a fusion protein consisting of the amino acid sequence set forth in SEQ ID NO: 15 include a polynucleotide containing a polynucleotide consisting of the base sequence set forth in SEQ ID NO: 16. . Examples of the polynucleotide containing a polynucleotide encoding a fusion protein consisting of the amino acid sequence set forth in SEQ ID NO: 17 include a polynucleotide containing a polynucleotide consisting of the base sequence set forth in SEQ ID NO: 18. . Examples of the polynucleotide containing a polynucleotide encoding a fusion protein consisting of the amino acid sequence set forth in SEQ ID NO: 19 include a polynucleotide containing a polynucleotide consisting of the base sequence set forth in SEQ ID NO: 20. .

  The polynucleotide of the present invention may further contain a polynucleotide encoding a cleavable linker peptide between the first coding sequence and the second coding sequence. The cleavable linker peptide is as described above.

  The polynucleotide of the present invention comprises a polynucleotide (coding sequence) containing a polynucleotide encoding an amino acid sequence for promoting translation and / or a polynucleotide (coding sequence) containing a polynucleotide encoding an amino acid sequence for purification. ) May be included. As a polynucleotide containing a polynucleotide encoding an amino acid sequence for promoting translation, a polynucleotide containing a polynucleotide encoding an amino acid sequence for promoting translation used in the art may be used. it can. Examples of the amino acid sequence for promoting translation include those described above. As a polynucleotide encoding an amino acid sequence for purification, a polynucleotide containing a polynucleotide encoding an amino acid sequence for purification used in the art can be used. Examples of the amino acid sequence for purification include those described above. The polynucleotide (coding sequence) containing the polynucleotide encoding the amino acid sequence for purification is preferably present on the 5 'side of the first coding sequence.

3. Expression Vector and Transformant of the Present Invention Furthermore, the present invention provides an expression vector and a transformant containing the above-described polynucleotide of the present invention.
(1) Expression vector The expression vector of the present invention can be obtained by ligating (inserting) the polynucleotide (DNA) of the present invention into an appropriate vector. More specifically, it can be obtained by cleaving a purified polynucleotide (DNA) with a suitable restriction enzyme, inserting it into a restriction enzyme site or a multiple cloning site of a suitable vector, and ligating the vector.
Specific examples of the expression vector of the present invention include, for example,
(1) a promoter sequence that can induce expression;
(2) Formula (Z) _n
(Wherein n and Z represent the same meaning as described above.)
And a first coding sequence comprising a polynucleotide that encodes a polypeptide having a function of allowing the fusion protein to be expressed as a soluble protein when expressed as a fusion protein with the target protein; 3) An expression vector containing a second coding sequence containing a polynucleotide encoding the target protein can be mentioned.
The vector for inserting the polynucleotide of the present invention is not particularly limited as long as it can replicate in the host, and examples thereof include plasmids, bacteriophages, animal viruses and the like. Examples of plasmids include plasmids derived from E. coli (eg, pBR322, pBR325, pUC118, pUC119, etc.), plasmids derived from Bacillus subtilis (eg, pUB110, pTP5, etc.), and plasmids derived from yeast (eg, YEp13, YEp24, YCp50, etc.). can give. Examples of the bacteriophage include λ phage. Examples of animal viruses include retroviruses, vaccinia viruses, insect viruses (eg, baculoviruses) and the like. Moreover, a pCold I vector, a pCold II vector, a pCold III vector, a pCold IV vector (manufactured by Takara Bio Inc.) and the like can also be suitably used.

  The polynucleotide of the present invention is usually ligated so that it can be expressed downstream of a promoter (promoter capable of inducing expression) in an appropriate vector. The promoter used is preferably an SV40-derived promoter, a retrovirus promoter, a metallothionein promoter, a heat shock promoter, a cytomegalovirus promoter, an SRα promoter or the like when the host to be transformed is an animal cell. When the host is Escherichia, a Trp promoter, T7 promoter, lac promoter, recA promoter, λPL promoter, lpp promoter and the like are preferable. When the host is Bacillus, SPO1 promoter, SPO2 promoter, penP promoter and the like are preferable. When the host is yeast, PHO5 promoter, PGK promoter, GAP promoter, ADH1 promoter, GAL promoter, etc. are preferable. When the host is an insect cell, polyhedrin promoter, P10 promoter and the like are preferable. A promoter capable of inducing expression at a low temperature can also be suitably used. Examples of the promoter capable of inducing expression at a low temperature include a promoter sequence of a cold shock gene. Examples of cold shock genes include E. coli cold shock genes (eg, cspA, cspB, cspG, cspI, csdA, etc.), Bacillus caldolyticus cold shock genes (eg, Bc-Csp, etc.), Salmonella enterica cold shock genes (eg, cspE, etc.). Erwinia carotovora cold shock gene (for example, cspG etc.) and the like. Among them, for example, a cspA promoter, a cspB promoter, a cspG promoter, a cspI promoter, a csdA promoter and the like can be suitably used as a promoter capable of inducing expression at a low temperature.

  In addition to the above, the expression vector of the present invention may contain those containing an enhancer, a splicing signal, a poly A addition signal, a ribosome binding sequence (SD sequence), a selection marker and the like as desired. Examples of the selection marker include a dihydrofolate reductase gene, an ampicillin resistance gene, a neomycin resistance gene, and the like.

  Further, the expression vector of the present invention may include a polynucleotide containing a base sequence encoding an amino acid sequence for promoting translation and / or a polynucleotide containing a base sequence encoding an amino acid sequence for purification. Good. As the polynucleotide containing a base sequence encoding an amino acid sequence for promoting translation, a polynucleotide containing a base sequence encoding an amino acid sequence for promoting translation used in the art may be used. it can. Examples of the amino acid sequence for promoting translation include those described above. As a polynucleotide encoding an amino acid sequence for purification, a polynucleotide containing a base sequence encoding an amino acid sequence for purification used in the art can be used. Examples of the amino acid sequence for purification include those described above.

(2) Transformant By introducing the expression vector containing the polynucleotide of the present invention (that is, the polynucleotide encoding the fusion protein of the present invention) thus obtained into a suitable host, Transformants can be created. The host is not particularly limited as long as it can express the polynucleotide (DNA) of the present invention. For example, Escherichia, Bacillus, Pseudomonas, Rhizobium, yeast, animal cells or Insect cells. Examples of the genus Escherichia include Escherichia coli. Examples of the genus Bacillus include Bacillus subtilis. Examples of Pseudomonas spp. Include Pseudomonas putida. Examples of the genus Rhizobium include Rhizobium meliloti. Examples of the yeast include Saccharomyces cerevisiae and Schizosaccharomyces pombe. Examples of animal cells include COS cells and CHO cells. Examples of insect cells include Sf9 and Sf21.

  The method for introducing the expression vector into the host and the transformation method using the expression vector can be performed by various general methods. Examples of methods for introducing an expression vector into a host cell include, for example, the calcium phosphate method (Virology, 52, 456-457 (1973)) and the lipofection method (Proc. Natl. Acad. Sci. USA, 84, 7413 (1987)). Electroporation method (EMBO J., 1, 841-845 (1982)). Examples of the transformation method of the genus Escherichia include the methods described in Proc. Natl. Acad. Sci. USA, 69, 2110 (1972), Gene, 17, 107 (1982) and the like. Examples of the method for transforming Bacillus include the method described in Molecular & General Genetics, 168, 111 (1979). Examples of yeast transformation methods include the method described in Proc. Natl. Acad. Sci. USA, 75, 1929 (1978). Examples of methods for transforming animal cells include the method described in Virology, 52, 456 (1973). Examples of the method for transforming insect cells include the method described in Bio / Technology, 6, 47-55 (1988). Thus, a transformant transformed with an expression vector containing a polynucleotide encoding the fusion protein of the present invention (polynucleotide of the present invention) can be obtained.

(3) Expression vector and transformant containing promoter sequence capable of inducing expression at low temperature As the expression vector of the present invention, an expression vector containing a promoter sequence capable of inducing expression at low temperature is particularly preferable. By using an expression vector containing a promoter sequence capable of inducing expression at a low temperature, the fusion protein of the present invention can be expressed as a soluble protein.
Specifically, an expression vector containing a promoter sequence capable of inducing expression at low temperature is:
(1) Promoter sequence capable of inducing expression at low temperature;
(2) Formula (Z) _n
(In the formula, n and Z have the same meaning as described above.)
A first coding sequence comprising a polynucleotide that encodes a polypeptide having an activity or function that can be expressed as a soluble protein when expressed as a fusion protein with the target protein; And (3) An expression vector containing a second coding sequence containing a polynucleotide encoding the protein of interest.
The polypeptide represented by formula (Z) _n is as described above.

As an expression vector containing a promoter sequence capable of inducing expression at low temperature,
(1) Promoter sequence capable of inducing expression at low temperature;
(2) Formula (Z) ₂
(In the formula, Z represents the same meaning as described above.)
And (3) an expression vector containing a second coding sequence containing a polynucleotide encoding the protein of interest.
The polypeptide represented by the formula (Z) ₂ is as described above.
The polynucleotide encoding the polypeptide represented by formula (Z) ₂ is also as described above.

  The promoter sequence capable of inducing expression at a low temperature means a promoter sequence capable of inducing the expression of the target protein by lowering the temperature from the culture conditions for growing the host cells. Examples of the promoter capable of inducing expression at a low temperature include a promoter of a gene encoding a cold shock protein (cold shock gene). Examples of the cold shock gene promoter include, for example, the cold shock gene promoter of Escherichia coli, Bacillus caldolyticus cold shock gene promoter (for example, Bc-Csp), Salmonella enterica cold shock gene promoter (for example, cspE), Erwinia carotovora Examples include cold shock gene promoters (eg, cspG). Examples of the E. coli cold shock gene promoter include cspA promoter, cspB promoter, cspG promoter, cspI promoter, csdA promoter and the like, with cspA promoter being preferred. Examples of the Bacillus caldolyticus cold shock gene promoter include Bc-Csp. Examples of the promoter of the Salmonella enterica cold shock gene include cspE. Examples of the Erwinia carotovora cold shock gene promoter include cspG.

  The temperature at which the promoter capable of inducing expression at a low temperature used in the present invention is usually 30 ° C. or lower, preferably 25 ° C. or lower, more preferably 20 ° C. or lower, particularly preferably 15 ° C. or lower. However, since the expression efficiency decreases when the temperature is too low, the expression is usually induced at 5 ° C or higher, preferably 10 ° C or higher, and particularly preferably about 15 ° C.

  When preparing an expression vector containing a promoter sequence capable of inducing expression at low temperature of the present invention, vectors for inserting the polynucleotide of the present invention include pCold I vector, pCold II vector, pCold III vector, pCold IV vector (Above, manufactured by Takara Bio Inc.) and the like can be suitably used. When these vectors are used to express prokaryotic cells as a host, the fusion protein of the present invention can be produced as a soluble protein in the cytoplasm of the host cell.

  As a host into which an expression vector containing a promoter sequence capable of inducing expression at low temperature of the present invention is introduced, prokaryotic cells are preferable, Escherichia coli is more preferable, particularly BL21 strain and JM109 strain are preferable, and BL21 strain is particularly preferable.

  The culture temperature for cell growth of the transformant introduced with the expression vector containing a promoter sequence capable of inducing expression at a low temperature of the present invention is usually 25 to 40 ° C., preferably 30 to 37 ° C. The temperature for inducing expression is usually 4 to 25 ° C, preferably 10 to 20 ° C, more preferably 12 to 18 ° C, and particularly preferably 15 ° C.

In addition, as the expression vector of the present invention,
(1) a promoter sequence that can induce expression;
(2) Formula (Z) _n
(In the formula, n and Z have the same meaning as described above.)
A first coding sequence comprising a polynucleotide that encodes a polypeptide having an activity or function that can be expressed as a soluble protein when expressed as a fusion protein with the target protein; And (3) an expression vector containing at least one restriction enzyme site into which a second coding sequence containing a polynucleotide encoding the target protein can be inserted.
As a promoter capable of inducing expression, a promoter capable of inducing expression at a low temperature is preferable.
The polypeptide represented by formula (Z) _n is as described above.
“At least one restriction enzyme site capable of inserting a second coding sequence containing a polynucleotide encoding a protein of interest” refers to inserting a second coding sequence containing a polynucleotide encoding a protein of interest A polynucleotide comprising a polynucleotide having a restriction enzyme recognition site. The restriction enzyme site is not particularly limited as long as a second coding sequence containing a polynucleotide encoding the target protein can be inserted, but is preferably a so-called multicloning site. Restriction enzyme sites such as multicloning sites are well known and reported in the art (eg, Yanisch-Perron, C., Vieira, J. and Messing, J. Gene 33 (1985) 103-119, Improved M13 phage cloning vectors and host strains: Nucleotide sequences of the M13mp18 and pUC19 vectors. See Gene 33 (1985) 103-119).

  In such an expression vector, (3) the polynucleotide encoding the target protein is linked to at least one restriction enzyme site into which the second coding sequence containing the polynucleotide encoding the target protein can be inserted ( Insertion), an expression vector capable of expressing the fusion protein of the present invention can be prepared.

Among such expression vectors,
(1) Promoter sequence capable of inducing expression at low temperature;
(2) Formula (Z) ₂
(In the formula, Z represents the same meaning as described above.)
A first coding sequence containing a polynucleotide encoding a polypeptide represented by: and (3) at least one restriction enzyme into which a second coding sequence containing a polynucleotide encoding a protein of interest can be inserted. Expression vectors containing the site are preferred.
The polypeptide represented by the formula (Z) ₂ is as described above.
The polynucleotide encoding the polypeptide represented by formula (Z) ₂ is also as described above.

A polynucleotide encoding a cleavable linker peptide may further be included between the first coding sequence and the at least one restriction enzyme site. The cleavable linker peptide is as described above.
A coding sequence containing a polynucleotide encoding an amino acid sequence for purification may further be contained on the 5 ′ side of the first coding sequence. The amino acid sequence for purification is as described above.

4). Production of fusion protein of the present invention The present invention also provides a method for producing the fusion protein of the present invention, comprising the steps of culturing the transformant to produce the fusion protein of the present invention. In the fusion protein of the present invention, the transformant is cultured under conditions capable of expressing the polynucleotide (DNA) encoding the fusion protein of the present invention, and the fusion protein of the present invention is produced, accumulated, separated and purified. Can be manufactured.

(Culture of transformants)
The transformant of the present invention can be cultured according to a usual method used for host culture. By the culture, the fusion protein of the present invention is produced by the transformant, and the fusion protein of the present invention is accumulated in the transformant or in the culture solution.

  As a medium for cultivating transformants whose hosts are Escherichia or Bacillus genus, it contains a carbon source, nitrogen source, inorganic salts, etc. necessary for the growth of the transformant, so that transformants can be cultured efficiently. Any natural or synthetic medium may be used as long as it can be performed automatically. As the carbon source, carbohydrates such as glucose, fructose, sucrose and starch, organic acids such as acetic acid and propionic acid, and alcohols such as ethanol and propanol are used. As the nitrogen source, ammonia, ammonium salts of inorganic or organic acids such as ammonium chloride, ammonium sulfate, ammonium acetate, and ammonium phosphate, or other nitrogen-containing compounds, peptone, meat extract, corn steep liquor, and the like are used. Examples of inorganic salts include monopotassium phosphate, dipotassium phosphate, magnesium phosphate, magnesium sulfate, sodium chloride, ferrous sulfate, manganese sulfate, copper sulfate, and calcium carbonate. During culture, an antibiotic such as ampicillin or tetracycline may be added to the medium as necessary. When culturing a transformant transformed with an expression vector using an inducible promoter as a promoter, an inducer may be added to the medium as necessary. For example, when cultivating a transformant transformed with an expression vector using the Lac promoter, transformation by transforming isopropyl-β-D-thiogalactopyranoside (IPTG) with an expression vector using the trp promoter When culturing the body, indoleacrylic acid (IAA) or the like may be added to the medium.

  When the host is an Escherichia bacterium, the culture is usually carried out at about 15 to 43 ° C. for about 3 to 24 hours, and if necessary, aeration or agitation is added. When the host is a genus Bacillus, the culture is usually performed at about 30 to 40 ° C. for about 6 to 24 hours, and if necessary, aeration or agitation is added.

  As a medium for cultivating a transformant whose host is yeast, for example, a Burkholder minimum medium (Proc. Natl. Acad. Sci. USA, 77, 4504 (1980)) or 0.5% (w / v ) SD medium containing casamino acid (Proc. Natl. Acad. Sci. USA, 81, 5330 (1984)). The pH of the medium is preferably adjusted to about 5-8. Culture is usually performed at about 20 ° C. to 35 ° C. for about 24 to 72 hours, and aeration and agitation are added as necessary.

  As a medium for culturing a transformant whose host is an animal cell, for example, a MEM medium (Science, 122, 501 (1952)) containing about 5 to 20% (v / v) fetal calf serum, a DMEM medium (Virology) , 8, 396 (1959)). The pH is preferably about 6-8. The culture is usually performed at about 30 ° C. to 40 ° C. for about 15 to 60 hours, and aeration and agitation are added as necessary.

  As a medium for cultivating transformants whose host is an insect cell, an appropriate addition of an additive such as 10% (v / v) bovine serum inactivated in Grace's Insect Medium (Nature, 195, 788 (1962)) Is used. The pH of the medium is preferably adjusted to about 6.2 to 6.4. The culture is usually performed at about 27 ° C. for about 3 to 5 days, and aeration and agitation are added as necessary.

  The culture temperature for cell growth and the temperature for inducing expression of the transformant introduced with the expression vector containing the promoter sequence capable of inducing expression at low temperature of the present invention are as described above.

(Separation and purification of the fusion protein of the present invention)
The fusion protein of the present invention can be obtained by separating and purifying the fusion protein of the present invention from the culture. Here, the culture means any of a culture solution, cultured cells or cultured cells, or disrupted cultured cells or cultured cells. Separation and purification of the fusion protein of the present invention can be carried out according to ordinary methods.

  Specifically, when the fusion protein of the present invention is accumulated in cultured cells or cultured cells, after culturing, the cells or cells are removed by a usual method (for example, ultrasonic, lysozyme, freeze-thaw, etc.). After crushing, a crude extract of the fusion protein of the present invention can be obtained by ordinary methods (eg, centrifugation, filtration, etc.). When the fusion protein of the present invention is accumulated in the periplasmic space, an extract containing the target protein can be obtained by an ordinary method (for example, osmotic shock method) after completion of the culture. When the fusion protein of the present invention is accumulated in the culture solution, the cells or cells and the culture supernatant are separated from each other by a conventional method (for example, centrifugation, filtration, etc.) after completion of the culture. A culture supernatant containing the fusion protein of the invention can be obtained.

  Purification of the fusion protein of the present invention contained in the extract or culture supernatant thus obtained can be performed according to a conventional separation / purification method. Separation / purification methods include, for example, ammonium sulfate precipitation, gel filtration chromatography, ion exchange chromatography, affinity chromatography, reverse phase high performance liquid chromatography, dialysis, ultrafiltration, etc., alone or in appropriate combination. be able to. When the fusion protein of the present invention contains the above-described amino acid sequence for purification, it is preferably purified using this. Specifically, when the fusion protein of the present invention contains a histidine tag sequence, a nickel chelate affinity chromatography method is used, and when the fusion protein of the present invention contains a binding domain to glutathione of S-transferase, an affinity chromatography method using a glutathione binding gel is used. Can be used.

  The objects, features, advantages, and ideas of the present invention will be apparent to those skilled in the art from the description of the present specification, and those skilled in the art can easily implement the present invention from the description of the present specification. it can. The best mode for carrying out the invention and specific examples show preferred embodiments of the present invention and are shown for illustration or description, and the present invention is not limited thereto. Not what you want. It will be apparent to those skilled in the art that various modifications can be made based on the description of the present specification within the spirit and scope of the present invention disclosed herein.

Reference Example 1 Construction of apoAQ expression vector (pCold-AQ) The aequorin gene encoding the calcium-binding photoprotein apoaequorin (Apoaequorin may be abbreviated as “apoAQ”) is pAQ440 (Japanese Patent Laid-Open No. 61-135586). It was prepared by PCR from pAM-HE containing the HindIII-EcoRI fragment, which is a coding region of No. gazette). A pCold II vector (Takara Bio Inc.) was used as an expression vector.
Two PCR primers using pAM-HE as a template: AQ-EcoRI-Met (5 'ccg GAA TTC ATG AAA CTT ACA TCA GAC TTC GAC AAC 3' (SEQ ID NO: 27); EcoRI restriction enzyme site is underlined) and Using AQ-C-SalI (5 'cgc gtc gac tta ggg gac agc tcc acc gta gag ctt 3' (SEQ ID NO: 28); SalI restriction enzyme site is underlined), PCR kit (manufactured by Takara Bio Inc.) PCR (cycle conditions 25 cycles; 1 minute / 94 ° C., 1 minute / 50 ° C., 1 minute / 72 ° C.) was performed to amplify the desired aequorin gene region. The obtained DNA fragment was purified with a PCR purification kit (Qiagen). The purified DNA fragment was digested with restriction enzymes EcoRI / SalI by a conventional method, and then ligated to the restriction enzyme EcoRI / SalI sites of pColdII to construct the expression vector pCold-AQ shown in FIG. The insert DNA was confirmed by determining the base sequence with a DNA sequencer (manufactured by ABI).

Example 1 Construction of ZZ-Apo AQ Fusion Protein Expression Vector (pCold-ZZ-AQ) In order to express a recombinant ZZ- apo AQ fusion protein in E. coli, the ZZ gene and the aequorin gene were prepared according to the method described below. . A ZZ gene encoding a ZZ domain that is an IgG binding domain was prepared from pEZZ18 (Amersham Biosciences) by PCR. The aequorin gene encoding apoaequorin was prepared by PCR from pAM-HE containing HindIII-EcoRI fragment which is the coding region of pAQ440 (see JP-A-61-135586). A pCold II vector (Takara Bio Inc.) was used as an expression vector. A method for constructing a ZZ-ApoAQ fusion protein expression vector is as follows.

Two PCR primers using pEZZ18 as template:
6ZZ-N-NdeI (5 'CCG CAT ATG GCG CAA CAC GAT GAA GCC GTG3' (SEQ ID NO: 29); NdeI restriction enzyme site is underlined) and
PCR with 7ZZ-C-BamHI (5 ′ GGC GGA TCC CGA GCT CGA ATT TGC GTC TAC3 ′ (SEQ ID NO: 30); BamHI restriction enzyme site is underlined) with PCR kit (manufactured by Takara Bio Inc.) Cycle conditions 25 cycles; 1 min / 94 ° C., 1 min / 50 ° C., 1 min / 72 ° C.) were performed to amplify the desired DNA region. The obtained DNA fragment was purified with a PCR purification kit (Qiagen). The purified DNA fragment is digested with the restriction enzyme NdeI / BamHI by a conventional method, and then ligated to the restriction enzyme NdeI / BamHI site of pCold-AQ obtained in Reference Example 1, thereby expressing the expression vector pCold shown in FIG. -Built ZZ-AQ. This expression vector can be induced at low temperatures. The expressed ZZ-Apo AQ has a histidine doug at the amino terminus.

Reference Example 2 Construction of hGL expression vector (pCold-hGL) In order to express Gaussia luciferase protein derived from Gausia Princess, a deep-sea co-poda in Escherichia coli, Gaussia luciferase gene (hGL gene) PcDNA3-hGL (manufactured by LUX). PCold II (Takara Bio Inc.) was used as an expression vector.
Two kinds of PCR primers using pcDNA3-hGL (manufactured by LUX) having Gaussia luciferase gene as a template:
GL5-N / SacI (5 'gcc GAG CTC AAG CCC ACC GAG AAC AAC GAA 3' (SEQ ID NO: 31); SacI restriction enzyme site is underlined) and GL2-C / EcoRI (5 'gcc GAA TTC TTA GTC ACC ACC GGC CCC CTT 3 '(SEQ ID NO: 32); EcoRI restriction enzyme site is underlined, PCR with PCR kit (manufactured by Takara Bio Inc.) (cycle conditions 25 cycles; 1 minute / 94 ° C, 1 minute) / 50 ° C., 1 minute / 72 ° C.) to amplify the desired DNA region. The resulting fragment is purified with a PCR purification kit (Qiagen), digested with restriction enzymes SacI / EcoRI by a conventional method, and then ligated to the restriction enzyme SacI / EcoRI sites of pColdII to obtain the expression shown in FIG. The vector pCold-hGL was constructed.

Example 2 Construction of ZZ-hGL Expression Vector (pCold-ZZ-hGL) In order to express a recombinant ZZ-hGL fusion protein in E. coli, a ZZ gene and a Gaussia luciferase gene were prepared according to the method described below. The ZZ gene encoding the ZZ domain, which is an IgG binding domain, was prepared by PCR from pEZZ18 (Amersham Bioscience) having the ZZ gene. Gaussia luciferase gene (hGL gene) was prepared from pcDNA3-hGL (manufactured by LUX) having Gaussia luciferase gene by PCR. PCold II (Takara Bio Inc.) was used as an expression vector.
pcDNA3-hGL as a template, two PCR primers: GL6-N / EcoRI (5 'gcc GAA TTC AAG CCC ACC GAG AAC AAC GAA 3' (SEQ ID NO: 33); EcoRI restriction enzyme site is underlined) and GL- PCR with C / XbaI (5 'gcc TCT AGA TTA GTC ACC ACC GGC CCC CTT 3' (SEQ ID NO: 34); XbaI restriction enzyme site is underlined) with PCR kit (Takara Bio) Conditions 25 cycles; 1 min / 94 ° C., 1 min / 50 ° C., 1 min / 72 ° C.) were performed to amplify the desired DNA region. The resulting fragment was purified with a PCR purification kit (Qiagen), digested with restriction enzymes EcoRI / XbaI by a conventional method, and then ligated to the restriction enzyme EcoRI / XbaI sites of pCold-ZZ-AQ. The expression vector pCold-ZZ-hGL shown in 4 was constructed.

Reference Example 3 Construction of KAZ expression vector (pCold-KAZ) A 19 kDa protein-encoding gene (KAZ gene) is used to express a 19 kDa protein (KAZ), which is a catalytic unit of Evil luciferase derived from the deep-sea shrimp, Hime Shido shrimp, in Escherichia coli. Was prepared from pHis-KAZ (Inouye et al. FEBS Lett. 2000: 481, 19-25). PCold II (Takara Bio Inc.) was used as an expression vector.
Two PCR primers using pHis-KAZ as template:
KAZ-17N / NdeI (5 'gcg CAT ATG TTT ACG TTG GCA GAT TTC GTT 3' (SEQ ID NO: 35); NdeI restriction enzyme site is underlined) and KAZ-12C / EcoRI (5 'cgc GAA TTC TTA GGC AAG AAT GTT CTC GCA AAG CCT 3 ′ (SEQ ID NO: 36); EcoRI restriction enzyme site is underlined, PCR with PCR kit (manufactured by Takara Bio Inc.) (cycle conditions 25 cycles; 1 minute / 94 ° C., 1 min / 50 ° C., 1 min / 72 ° C.) to amplify the desired DNA region. The resulting fragment was purified with a PCR purification kit (Qiagen), digested with the restriction enzyme NdeI / EcoRI by a conventional method, and then ligated to the restriction enzyme NdeI / EcoRI site of pColdII to obtain the expression shown in FIG. The vector pCold-KAZ was constructed.

Example 3 Construction of ZZ-KAZ Expression Vector (pCold-ZZ-KAZ) In order to express a recombinant ZZ-KAZ fusion protein in E. coli, the ZZ gene and KAZ gene were prepared according to the method described below. The ZZ gene encoding the ZZ domain, which is an IgG binding domain, was prepared by PCR from pEZZ18 (Amersham Bioscience) having the ZZ gene. The shrimp-derived luciferase gene was prepared by PCR from pHis-KAZ (Inouye et al. FEBS Lett. 2000: 481, 19-25) having a shrimp-derived luciferase gene. As an expression vector, a pCold II expression vector (Takara Bio Inc.) was used.
Two PCR primers with pHis-KAZ-NX as template: KAZ-8N / EcoRI (5 'gcg GAA TTC TTT ACG TTG GCA GAT TTC GTT GGA 3' (SEQ ID NO: 37); EcoRI restriction enzyme site is underlined) And KAZ-5C / XbaI (5 ′ cc gc T CTA GA A TTA GGC AAG AAT GTT CTC GCA AAG-CCT 3 ′ (SEQ ID NO: 38); XbaI restriction enzyme site is underlined) PCR (cycle condition 25 cycles; 1 minute / 94 ° C., 1 minute / 50 ° C., 1 minute / 72 ° C.) was carried out by Bio Inc., and the desired DNA region was amplified. The resulting fragment was purified with a PCR purification kit (Qiagen), digested with restriction enzymes EcoRI / XbaI by a conventional method, and then ligated to the restriction enzyme EcoRI / XbaI sites of pCold-ZZ-AQ. The expression vector pCold-ZZ-KAZ shown in FIG. 6 was constructed.

Example 4 Construction of pCold-ZZ-T-hGL and pCold-ZZ-P-hGL Expression Vectors Thrombin or human in the fusion part for cleaving and removing the ZZ protein part from the ZZ fusion hGL protein shown in Example 2 Two vectors having a renovirus 3C protease cleavage site, pCold-ZZ-T-hGL or pCold-ZZ-P-hGL, were constructed as follows.
After digesting pCold-ZZ-hGL obtained in Example 2 with restriction enzymes BamHI / EcoRI, an oligonucleotide corresponding to the protease cleavage site sequence was synthesized and inserted. Thrombin B / EF 5 ′ GA TCT CTG GTT CCG CGT GGA TCC G 3 ′ (SEQ ID NO: 39) and Thrombin B / ER 5 ′ AA TTC GGA TCC ACG CGG AAC CAG A 3 ′ (SEQ ID NO: 40) was used. Human renovirus 3C protease cleavage recognition sequence oligonucleotides include PreScission B / EF 5 ′ GA TCT CTG GAA GTT CTG TTC CAG GGG CCC G 3 ′ (SEQ ID NO: 41) and PreScission B / E-R5 ′ AA TTC GGG CCC CTG GAA CAG AAC TTC CAG A 3 ′ (SEQ ID NO: 42) was used. These oligonucleotides were annealed and inserted into the expression vector pCold-ZZ-T-hGL shown in FIG. 7 or the expression vector pCold-ZZ-T-hGL shown in FIG. The expression vector pCold-ZZ-P-hGL shown was constructed.

Example 5 Preparation Method of Recombinant ZZ-Apo AQ Fusion Protein Recombinant ZZ-apo AQ fusion protein was prepared by expressing recombinant ZZ-apo AQ fusion protein after expression in E. coli as described below. The extracted fusion protein was extracted, and the extracted fusion protein was purified using various chromatographic methods.
The measurement of the luminescence activity of the fusion protein during the purification process was performed as follows. First, in 1 ml of 50 mM Tris-HCl (pH 7.6) buffer containing 10 mM EDTA, a crude ZZ-apo AQ fusion protein solution, 2-mercaptoethanol (1 μl), and a substrate coelenterazine dissolved in ethanol (1 μg / μl) ) And then left on ice (4 ° C.) for 2 hours to prepare a ZZ-AQ fusion protein having luminescence activity. Luminescence reaction was started by adding 100 μl of 50 mM CaCl ₂ to the obtained ZZ-AQ fusion protein solution, and luminescence activity was measured for 10 seconds with a luminescence measuring device PSN AB2200 (manufactured by ATTO). Luminescent activity (maximum value (Imax) etc.) was evaluated by relative luminescence intensity (rlu).

1) Expression of recombinant ZZ-apo AQ fusion protein in Escherichia coli The expression vector pCold-ZZ-AQ obtained in Example 1 was introduced into the Escherichia coli BL21 strain by the polyethylene glycol method to obtain a transformed strain. The obtained transformant was cultured at 37 ° C. for 18 hours. After culturing, the transformed strain is inoculated into 10 ml of LB liquid medium (10 g of bactotryptone, 5 g of yeast extract, 5 g of sodium chloride, pH 7.2 per liter of water) containing ampicillin (100 μg / ml). The culture was further performed at 37 ° C. for 18 hours. Subsequently, the cultured bacterial cell solution was added to 2 liters of fresh LB liquid medium (400 ml × 5) and cultured at 37 ° C. for 4.5 hours. After culturing, the cultured bacterial solution is cooled on ice water, and isopropyl-β-D (−)-thiogalactopyranoside (IPTG, manufactured by Wako Pure Chemical Industries, Ltd.) is cultured to a final concentration of 0.1 mM. And cultured at 15 ° C. for 17 hours. The cultured cells were collected at 5,000 rpm (6000 × g) for 5 minutes using a cooling centrifuge.

2) Extraction of ZZ-ApoAQ fusion protein from cultured cells Suspend the cells collected in 1) above in 200 ml (40 ml x 5) 50 mM Tris-HCl (pH 7.6). Sonication treatment (Branson, Sonifier Model 250) was performed 3 times for 2 minutes each. The cell disruption solution was centrifuged at 10,000 rpm (12,000 × g) for 20 minutes, and the obtained soluble fraction was used as a starting material for purifying the ZZ-apo AQ fusion protein.

3) Purification of ZZ-ApoAQ fusion protein by Q-Sepharose column chromatography The soluble fraction (200 ml) obtained in 2) above was equilibrated with 50 mM Tris-HCl (pH 7.6). After adding and adsorbing to a Sepharose column (Amersham Biosciences, column size: diameter 2.5 × 6 cm), the column was washed with 250 ml of 50 mM Tris-HCl (pH 7.6). The protein adsorbed on the column was eluted in a total volume of 100 ml with a linear concentration gradient with a sodium chloride concentration of 0 to 1.0 M. Elution of ZZ-apo AQ fusion protein having luminescence activity was confirmed at a sodium chloride concentration of 0.45 to 0.65 M (25 ml; ZZ-apo AQ activity fraction).

4) Purification of ZZ-Apo AQ fusion protein by nickel chelate column chromatography
The ZZ-ApoAQ active fraction eluted from the Q-Sepharose column was added to a nickel chelate column (Amersham Biosciences, column size: diameter 1.5 × 5 cm) equilibrated with 50 mM Tris-HCl (pH 7.6). A ZZ-apo AQ fusion protein was adsorbed. The adsorbed ZZ-Apo AQ fusion protein was eluted with a linear concentration gradient having an imidazole concentration of 0 to 0.3 M (manufactured by Wako Pure Chemical Industries, Ltd.) in a total volume of 100 ml. The elution of the ZZ-apo AQ fusion protein having luminescence activity was confirmed at an imidazole concentration of 0.06 to 0.12 M (26 ml; ZZ-apo AQ activity fraction).

5) Purification of ZZ-ApoAQ fusion protein by IgG-Sepharose column chromatography A portion of the ZZ-ApoAQ active fraction eluted from the nickel chelate column was subjected to Amicon Ultra-4 centrifugal filter device (molecular weight 10,000 cut; Concentrated using Millipore). 4 ml of the concentrated solution was added to an IgG-Sepharose 6 FastFlow column (Amersham Biosciences, column size: diameter 1.5 × 4 cm) to adsorb the ZZ-Apo AQ fusion protein. The adsorbed ZZ-Apo AQ fusion protein was eluted with 0.5 M ammonium acetate (pH 3.4) (manufactured by Wako Pure Chemical Industries, Ltd.).
The purity was confirmed to be 95% or more by 12% SDS-polyacrylamide electrophoresis as shown in FIG.
The purification yields are summarized in Table 1. By using an IgG Sepharose column, purified ZZ-Apo AQ having a purity of 95% or more and 7.8 mg was obtained from 420 ml of the culture solution.

Example 6 Preparation Method of ZZ-AQ Fusion Protein Conversion from ZZ-Apo AQ fusion protein to ZZ-AQ fusion protein was performed under the following conditions.
The purified ZZ-ApoAQ fusion protein (1 mg) obtained in Example 5 was dissolved in 5 ml of 50 mM Tris-HCl (pH 7.6) containing 10 mM DTT and 10 mM EDTA, and 24 μg of 1.2-fold equivalent coelenterazine dissolved in ethanol was dissolved. In addition, it was left overnight at 4 ° C. and converted into a ZZ-AQ fusion protein. The obtained ZZ-AQ fusion protein was concentrated with Amicon Ultra-4 (molecular weight 10,000 cut), washed with 8 ml of 50 mM Tris-HCl (pH 7.6) containing 10 mM EDTA (4 times 2 ml), and excess coelenterazine. Was excluded. A ZZ-AQ fusion protein was obtained with an activity recovery rate of 95%.

Example 7 Measurement of fermentation activity of recombinant protein (1) Expression of recombinant protein in Escherichia coli
ZZ fusion protein expression vector (pCold-ZZ-AQ, pCold-ZZ-hGL, pCold-ZZ-KAZ) or ZZ non-fusion protein expression vector (pCold-AQ, pCold-hGL, pCold-KAZ) hosted by polyethylene glycol method The product was introduced into E. coli BL21 strain to obtain a transformant. The obtained transformant was treated with 10 ml of LB liquid medium containing ampicillin (100 μg / ml) (10 g of bactotryptone, 5 g of yeast extract, 5 g of sodium chloride, pH 7.2 per liter of water) (in this example) All the following cultures were similarly inoculated into LB liquid medium) and further cultured at 37 ° C. for 18 hours. Subsequently, the cultured bacterial cell solution was added to 10 ml of a new LB liquid medium and cultured at 37 ° C. for 4.5 hours. After culturing, the culture solution is cooled on ice water, and isopropyl-β-D (−)-thiogalactopyranoside (IPTG, manufactured by Wako Pure Chemical Industries, Ltd.) is added to the culture solution to a final concentration of 0.1 mM. The mixture was added and cultured at 15 ° C. for 17 hours. 1 ml of the cultured cells was collected at 5,000 rpm (6000 × g) for 5 minutes by a cooling centrifuge.

(2) Extraction of recombinant protein from cultured cells The collected cells are suspended in 50 mM Tris-HCl (pH 7.6) containing 1 ml of 10 mM EDTA, and subjected to ultrasonic crushing treatment with ice cooling (Branson) Made by Sonifire Model 250) for 30 seconds. The cell disruption solution was centrifuged at 10,000 rpm (12,000 × g) for 3 minutes, and the supernatant was used as a soluble fraction. Next, the precipitate was suspended in 1 ml of 50 mM Tris-HCl (pH 7.6) containing 10 mM EDTA and used as an insoluble fraction.

(3-1) Measurement of luminescent activity of photoprotein aequorin 50 μl of the soluble fraction and insoluble fraction obtained in (2) above were dissolved in 50 mM Tris-HCl (pH 7.6) containing 0.95 ml of 10 mM EDTA, After mixing 2-mercaptoethanol (1 μl) and the substrate coelenterazine (1 μg / μl) dissolved in ethanol, add the apoaequorin fraction and leave it on ice (4 ° C.) for 2 hours to obtain aequorin with luminescent activity Regenerated. Luminescence reaction was started by adding 100 μl of CaCl ₂ to 1 μl of regenerated aequorin, and the luminescence activity was measured for 10 seconds with a luminescence measuring device Luminescencer-PSN AB2200 (manufactured by ATTO). Luminescent activity was evaluated by the average value (rlu) of the maximum value (Imax) of luminescent activity after measuring the above-mentioned luminescent activity three times.

(3-2) Measurement of luminescence activity of Evil luciferase 1 μl of the soluble fraction and the insoluble fraction obtained in (2) above were dissolved in 50 mM Tris-HCl (pH 7.6) containing 0.1 ml of 10 mM EDTA, and ethanol was added. The substrate coelenterazine (1 μg / μl) dissolved in was mixed to start the luminescence reaction, and the luminescence activity was measured for 60 seconds with a luminescence measuring device Luminescencer-PSN AB2200 (manufactured by Ato). Luminescent activity was evaluated by the average value (rlu) of the maximum value (Imax) of luminescent activity after measuring the above-mentioned luminescent activity three times.

(3-3) Measurement of luminous activity of Gaussia luciferase 1 μl of the soluble fraction and the insoluble fraction obtained in (2) above was dissolved in 50 mM Tris-HCl (pH 7.6) containing 0.1 ml of 10 mM EDTA, The substrate coelenterazine (1 μg / μl) dissolved in ethanol was mixed to start the luminescence reaction, and the luminescence activity was measured for 60 seconds with a luminescence measuring device Luminescencer-PSN AB2200 (manufactured by Ato). Luminescent activity was evaluated by the average value (rlu) of the maximum value (Imax) of luminescent activity after measuring the above-mentioned luminescent activity three times.
The results are shown in Table 2. When a heterologous protein is expressed in E. coli, the solubility is clearly higher when expressed as a ZZ fusion protein.

Apoaequorin (apo AQ) has three cysteine residues in the molecule. In expression in E. coli, apoaequorin is expressed as an insoluble protein when expressed at normal temperature (37 ° C.). It is necessary to use a denaturing agent for solubilization. However, when expressed as a ZZ fusion protein, ZZ-apoAQ was soluble and could be changed (regenerated) to aequorin having luminescent activity. In addition, the insoluble fraction in pCold-AQ, when expressed at a low temperature, was about 30% more without a denaturant and could be regenerated into aequorin.
Furthermore, Gaussia luciferase (hGL) has 10 cysteine residues in the molecule. Natural Gaussia luciferase is known to have its luminescence activity completely inactivated by treatment with a reducing agent. Gaussia luciferase is known to have poor refolding efficiency in E. coli. However, when expressed as a ZZ fusion protein, it was shown that the refolding efficiency was about 5 times higher than that of the ZZ non-fusion protein expression system. It was also suggested that refolding efficiency may be improved by culturing at low temperature.
On the other hand, when Evil luciferase (KAZ) is expressed in E. coli, it is expressed as an insoluble protein as described in (Inouye et al. FEBS Lett. 2000: 481, 19-25). The luminescence activity of is very low. However, it was revealed that KAZ expressed as a ZZ fusion protein is soluble and has luminescent activity.

Example 8 SDS-PAGE Analysis of Recombinant Protein (1) Expression of Recombinant Protein in E. coli
ZZ fusion protein expression vector (pCold-ZZ-AQ, pCold-ZZ-hGL, pCold-ZZ-KAZ, pCold-ZZ-T-hGL, pCold-ZZ-P-hGL) or ZZ non-fusion protein expression vector (pCold- AQ, pCold-hGL, pCold-KAZ) were introduced into the host E. coli BL21 strain by the polyethylene glycol method to obtain transformants. The obtained transformant was inoculated into 10 ml of LB liquid medium containing ampicillin (100 μg / ml) (10 g of bactotryptone, 5 g of yeast extract, 5 g of sodium chloride, pH 7.2 per liter of water), Furthermore, culture was performed at 37 ° C. for 18 hours. Next, 0.1 ml of the cultured bacterial cell solution was added to 10 ml of fresh LB liquid medium and cultured at 37 ° C. for 4.5 hours. After culturing, the culture solution is cooled on ice water, and isopropyl-β-D (−)-thiogalactopyranoside (IPTG, manufactured by Wako Pure Chemical Industries, Ltd.) is added to the culture solution to a final concentration of 0.1 mM. The mixture was added and cultured at 15 ° C. for 17 hours. 1 ml of cultured cells was collected at 5,000 rpm (6000 × g) for 5 minutes using a cooling centrifuge.
(2) Extraction of recombinant protein from cultured bacterial cells The collected bacterial cells are suspended in 50 mM Tris-HCl (pH 7.6) containing 0.5 ml of 10 mM EDTA, and subjected to ultrasonic crushing treatment (Branson Sonicator model 250) manufactured by the company was carried out for 30 seconds. The cell disruption solution was centrifuged at 10,000 rpm (12,000 × g) for 3 minutes, and the supernatant was used as the soluble fraction (S). The precipitate was then suspended in 0.5 ml of 50 mM Tris-HCl (pH 7.6) containing 10 mM EDTA and used as the insoluble fraction (P).
(3) SDS-PAGE analysis of recombinant protein 20 μl of Laemmli sample buffer was added to 20 μl of the soluble and insoluble fractions obtained in (2) above, treated at 95 ° C. for 3 minutes, and 12% (w / v) An SDS-PAGE gel (manufactured by TEFCO) was subjected to 90 min electrophoresis at 25 mA. The gel after electrophoresis was treated with a fixing solution (methanol: acetic acid: water = 50 ml: 10 ml: 40 ml) for 30 minutes and then stained with a colloid CBB staining kit (manufactured by TEFCO) for 1 hour. Decolorization was performed by washing with 200 ml of distilled water. The results are shown in FIG. When pCold-AQ, pCold-hGL, and pCold-KAZ, which are ZZ non-fusion protein expression vector systems, were used, the expressed protein was found mainly in the insoluble fraction (P). On the other hand, when pCold-ZZ-AQ, pCold-ZZ-hGL, and pCold-ZZ-KAZ, which are ZZ fusion protein expression vector systems, were used, the expressed protein was found mainly in the possibility fraction (S). . This result was also correlated with the luminescence activity, and the luminescence activity was higher when expressed as a ZZ fusion protein than when expressed as a ZZ non-fusion protein.
From these results, it was shown that the active protein can be efficiently expressed as a soluble protein by fusing with the ZZ protein.
Similarly, in the expression using pCold-ZZ-T-hGL and pCold-ZZ-P-hGL vectors having a protease cleavage recognition site, as shown in FIG. 11, an active protein is efficiently converted into a soluble protein. It was shown that it can be expressed.

According to the expression vector of the present invention and the method for producing the target protein of the present invention, since the target protein can be manufactured as a soluble protein, it is not necessary to solubilize the target protein. Therefore, according to the present invention, the target protein can be obtained efficiently and at a high recovery rate. Therefore, the present invention is useful for producing useful proteins and proteins such as proteins whose functions and structures are to be analyzed.
In addition, the expression vector containing at least one restriction enzyme site of the present invention can be produced as a soluble protein by inserting a gene encoding the target protein into the restriction enzyme site and expressing it. Therefore, the expression vector can be suitably used for production of a target protein such as a useful protein.

FIG. 1 shows the expression vector pCold-AQ obtained in Reference Example 1. FIG. 2 shows the expression vector pCold-ZZ-AQ obtained in Example 1. FIG. 3 shows the expression vector pCold-hGL obtained in Reference Example 2. FIG. 4 shows the expression vector pCold-ZZ-hGL obtained in Example 2. FIG. 5 shows the expression vector pCold-KAZ obtained in Reference Example 3. FIG. 6 shows the expression vector pCold-ZZ-KAZ obtained in Example 3. FIG. 7 shows the expression vector pCold-ZZ-T-hGL obtained in Example 4. FIG. 8 shows the expression vector pCold-ZZ-P-hGL obtained in Example 4. FIG. 9 is a diagram showing the results of SDS-PAGE analysis in the purification process of ZZ-apoaequorin in Example 5. Samples in each lane are as follows. Lane 1: protein molecular weight marker (Tefco): β-galactosidase (116,000), phospholipase B (97,400), bovine serum albumin (69,000), glutamate dehydrogenase (55,000), lactate dehydrogenase (36,500), carbonic acid dehydrogenase (29,000) , Trypsin inhibitor (20,100), Lane 2: Supernatant obtained by centrifuging an ultrasonic disruption of an E. coli transformant expressing recombinant ZZ-apoAQ at 12,000 g (Protein 5.4 μg), Lane 3 : Elution fraction from Q-sepharose column (protein 16 μg), Lane 4: Elution fraction from nickel chelate column (protein 4.8 μg), Lane 5: Elution fraction from IgG sepharose column (protein 1.3 μg). 10 is a diagram showing the results of SDS-PAGE analysis of Example 8. FIG. In the figure, M is a protein molecular weight marker (Tefco): β-galactosidase (116,000), phospholipase B (97,400), bovine serum albumin (69,000), glutamate dehydrogenase (55,000), lactate dehydrogenase (36,500), carbonic acid dehydrogenase ( 29,000), trypsin inhibitor (20,100). The soluble fraction of the supernatant obtained by centrifuging an ultrasonically disrupted E. coli transformed strain expressing the expression plasmid at 12,000 g for 3 minutes was designated as S, and the insoluble fraction of the precipitate as P. FIG. 11 is a diagram showing the results of SDS-PAGE analysis of Example 8. Samples in each lane are as follows. Lane 1: protein molecular weight marker (Tefco): β-galactosidase (116,000), phospholipase B (97,400), bovine serum albumin (69,000), glutamate dehydrogenase (55,000), lactate dehydrogenase (36,500), carbonic acid dehydrogenase (29,000) , Trypsin inhibitor (20,100), lane 2: supernatant obtained by centrifuging an ultrasonic disruption of a transformant of E. coli expressing recombinant ZZ-P-hGL at 12,000 g for 3 minutes (soluble fraction ( S)), Lane 3: Precipitation (insoluble fraction (P)) obtained by centrifuging an ultrasonically disrupted E. coli transformant expressing recombinant ZZ-P-hGL at 12,000 g for 3 minutes. Lane 4: Supernatant obtained by centrifuging an ultrasonic disruption of an E. coli transformant expressing recombinant ZZ-T-hGL at 12,000 g for 3 minutes (soluble fraction) (S)), Lane 5: Precipitation obtained by centrifuging an ultrasonically disrupted E. coli transformant expressing recombinant ZZ-T-hGL at 12,000 g for 3 minutes (insoluble fraction (P)) .

[SEQ ID NO: 1] This represents the amino acid sequence of the polypeptide represented by formula Z.
[SEQ ID NO: 2] This shows the base sequence of DNA encoding the amino acid sequence represented by SEQ ID NO: 1.
[SEQ ID NO: 3] This shows the amino acid sequence of the polypeptide represented by formula (Z) ₂ .
[SEQ ID NO: 4] This shows the base sequence of DNA encoding the amino acid sequence represented by SEQ ID NO: 3.
[SEQ ID NO: 5] This shows the amino acid sequence of recombinant apoaequorin encoded by DNA inserted into apoaequorin expression vector pCold-AQ prepared in Reference Example 1.
[SEQ ID NO: 6] This shows the base sequence of DNA encoding recombinant apoaequorin inserted into the apoaequorin expression vector pCold-AQ prepared in Reference Example 1.
[SEQ ID NO: 7] This shows the amino acid sequence of recombinant ZZ-apoiquorin fusion protein encoded by DNA inserted into ZZ-apoaequorin fusion protein expression vector pCold-ZZ-AQ prepared in Example 1.
[SEQ ID NO: 8] This shows the base sequence of the DNA encoding the recombinant ZZ-apoaequorin fusion protein inserted into the ZZ-apoaequorin fusion protein expression vector pCold-ZZ-AQ prepared in Example 1.
[SEQ ID NO: 9] This shows the amino acid sequence of recombinant Gaussia luciferase encoded by DNA inserted in Gaussia luciferase expression vector pCold-hGL prepared in Reference Example 2.
[SEQ ID NO: 10] This shows the base sequence of DNA encoding recombinant Gaussia luciferase inserted into Gaussia luciferase expression vector pCold-hGL prepared in Reference Example 2.
[SEQ ID NO: 11] The amino acid sequence of the recombinant ZZ-gaussia luciferase fusion protein encoded by the DNA inserted into the ZZ-gaussia luciferase fusion protein expression vector pCold-ZZ-hGL prepared in Example 2 Show.
[SEQ ID NO: 12] This shows the base sequence of DNA encoding recombinant ZZ-Gaussia luciferase fusion protein inserted into ZZ-Gaussia luciferase fusion protein expression vector pCold-ZZ-hGL prepared in Example 2.
[SEQ ID NO: 13] This shows the amino acid sequence of recombinant KAZ encoded by the DNA inserted into 19 KDa protein (KAZ) expression vector pCold-KAZ, which is the catalytic unit of Evil luciferase prepared in Reference Example 3.
[SEQ ID NO: 14] This shows the base sequence of DNA encoding recombinant KAZ inserted into 19 KDa protein (KAZ) expression vector pCold-KAZ, which is the catalytic unit of Evil luciferase prepared in Reference Example 3.
[SEQ ID NO: 15] This shows the amino acid sequence of recombinant ZZ-KAZ fusion protein encoded by DNA inserted into ZZ-KAZ fusion protein expression vector pCold-ZZ-KAZ prepared in Example 3.
[SEQ ID NO: 16] This shows the base sequence of the DNA encoding the recombinant ZZ-KAZ fusion protein inserted into the ZZ-KAZ fusion protein expression vector pCold-ZZ-KAZ prepared in Example 3.
[SEQ ID NO: 17] Recombinant ZZ-gau encoded by DNA inserted in ZZ-gaussia luciferase fusion protein expression vector pCold-ZZ-T-hGL having a thrombin cleavage site, prepared in Example 4 The amino acid sequence of sialiferase fusion protein is shown.
[SEQ ID NO: 18] encodes a recombinant ZZ-Gaussia luciferase fusion protein inserted in the ZZ-Gaussia luciferase fusion protein expression vector pCold-ZZ-T-hGL having a thrombin cleavage site, prepared in Example 4 This shows the base sequence of DNA.
[SEQ ID NO: 19] A set encoded by DNA inserted into the ZZ-Gaussia luciferase fusion protein expression vector pCold-ZZ-P-hGL having a human renovirus 3C protease cleavage site, prepared in Example 4. The amino acid sequence of the modified ZZ-Gaussia luciferase fusion protein is shown.
[SEQ ID NO: 20] Recombinant ZZ-Gaussia luciferase inserted in ZZ-Gaussia luciferase fusion protein expression vector pCold-ZZ-P-hGL having a human renovirus 3C protease cleavage site prepared in Example 4 This shows the base sequence of DNA encoding the fusion protein.
[SEQ ID NO: 21] This shows the amino acid sequence of apoaequorin.
[SEQ ID NO: 22] This shows the base sequence of DNA encoding apoaequorin.
[SEQ ID NO: 23] This shows the amino acid sequence of Gaussia luciferase.
[SEQ ID NO: 24] This shows the base sequence of DNA encoding Gaussia luciferase.
[SEQ ID NO: 25] This shows the amino acid sequence of 19 KDa protein (KAZ), which is the catalytic unit of Evil luciferase.
[SEQ ID NO: 26] This shows the base sequence of DNA encoding 19 KDa protein (KAZ) which is a catalytic unit of Evil luciferase.
[SEQ ID NO: 27] This shows the base sequence of the primer used in Reference Example 1.
[SEQ ID NO: 28] This shows the base sequence of the primer used in Reference Example 1.
[SEQ ID NO: 29] This shows the base sequence of the primer used in EXAMPLE 1.
[SEQ ID NO: 30] This shows the base sequence of the primer used in EXAMPLE 1.
[SEQ ID NO: 31] This shows the base sequence of the primer used in Reference Example 2.
[SEQ ID NO: 32] This shows the base sequence of the primer used in Reference Example 2.
[SEQ ID NO: 33] This shows the base sequence of the primer used in EXAMPLE 2.
[SEQ ID NO: 34] This shows the base sequence of the primer used in EXAMPLE 2.
[SEQ ID NO: 35] This shows the base sequence of the primer used in Reference Example 3.
[SEQ ID NO: 36] This shows the base sequence of the primer used in Reference Example 3.
[SEQ ID NO: 37] This shows the base sequence of the primer used in EXAMPLE 3.
[SEQ ID NO: 38] This shows the base sequence of the primer used in EXAMPLE 3.
[SEQ ID NO: 39] This shows the base sequence of the thrombin cleavage recognition sequence oligonucleotide used in EXAMPLE 4.
[SEQ ID NO: 40] This shows the base sequence of thrombin cleavage recognition sequence oligonucleotide used in EXAMPLE 4.
[SEQ ID NO: 41] This shows the base sequence of human renovirus 3C protease cleavage recognition sequence oligonucleotide used in EXAMPLE 4.
[SEQ ID NO: 42] This shows the base sequence of human renovirus 3C protease cleavage recognition sequence oligonucleotide used in EXAMPLE 4.

Claims (45)

(1) a promoter sequence that can induce expression;
(2) Formula (Z) _n
(In the formula, n represents an integer of 1 to 5, and Z represents a polypeptide selected from the group consisting of the following (a) to (d):
(A) a polypeptide comprising the amino acid sequence of SEQ ID NO: 1,
(B) a polypeptide comprising an amino acid sequence in which one or more amino acids are deleted, substituted, inserted and / or added in the amino acid sequence of SEQ ID NO: 1;
(C) a polypeptide comprising an amino acid sequence having 90% or more identity to the amino acid sequence of SEQ ID NO: 1, and (d) a polynucleotide comprising a base sequence complementary to the base sequence of SEQ ID NO: 2. A polypeptide comprising an amino acid sequence encoded by a polynucleotide that hybridizes under stringent conditions)
And a first coding sequence comprising a polynucleotide that encodes a polypeptide having a function that allows the fusion protein to be expressed as a soluble protein when expressed as a fusion protein with the target protein; 3) An expression vector containing a second coding sequence containing a polynucleotide encoding the target protein. The vector according to claim 1, wherein the polypeptide represented by the formula (Z) _n is a polypeptide represented by (Z) ₂ . The polypeptide represented by the formula (Z) ₂ is:
(E) a polypeptide consisting of the amino acid sequence of SEQ ID NO: 3,
(F) When the amino acid sequence of SEQ ID NO: 3 comprises an amino acid sequence in which one or more amino acids are deleted, substituted, inserted and / or added, and is expressed as a fusion protein with the target protein, A polypeptide having a function capable of expressing a fusion protein as a soluble protein,
(G) The fusion protein is expressed as a soluble protein when it consists of an amino acid sequence having 90% or more identity to the amino acid sequence of SEQ ID NO: 3 and is expressed as a fusion protein with the target protein. And (h) an amino acid sequence encoded by a polynucleotide that hybridizes under stringent conditions with a polynucleotide consisting of a base sequence complementary to the base sequence of SEQ ID NO: 4, and The vector according to claim 2, wherein the vector is a polypeptide selected from the group consisting of polypeptides having a function capable of being expressed as a soluble protein when expressed as a fusion protein with a target protein.   The vector according to any one of claims 1 to 3, wherein the promoter sequence capable of inducing expression is a promoter sequence capable of inducing expression at low temperature.   The vector according to claim 4, wherein the promoter sequence capable of inducing expression at a low temperature is a cold shock gene promoter sequence.   The vector according to claim 5, wherein the promoter sequence of the cold shock gene is an E. coli cold shock gene promoter sequence.   The vector according to claim 6, wherein the promoter sequence of the E. coli cold shock gene is a promoter sequence of the E. coli cold shock gene cspA, cspB, cspG, cspI or csdA.   8. The coding sequence according to claim 1, further comprising a coding sequence containing a polynucleotide encoding a cleavable linker peptide between the first coding sequence and the second coding sequence. vector.   The vector according to claim 8, wherein the cleavable linker peptide is a linker peptide having a protease cleavage site.   The vector according to any one of claims 1 to 9, further comprising a coding sequence containing a polynucleotide encoding an amino acid sequence for purification on the 5 'side of the first coding sequence.   The vector according to claim 10, wherein the amino acid sequence for purification is a histidine tag sequence. (1) a promoter sequence that can induce expression;
(2) Formula (Z) _n
(In the formula, n represents an integer of 1 to 5, and Z represents a polypeptide selected from the group consisting of the following (a) to (d):
(A) a polypeptide comprising the amino acid sequence of SEQ ID NO: 1,
(B) a polypeptide comprising an amino acid sequence in which one or more amino acids are deleted, substituted, inserted and / or added in the amino acid sequence of SEQ ID NO: 1;
(C) a polypeptide comprising an amino acid sequence having 90% or more identity to the amino acid sequence of SEQ ID NO: 1, and (d) a polynucleotide comprising a base sequence complementary to the base sequence of SEQ ID NO: 2. A polypeptide comprising an amino acid sequence encoded by a polynucleotide that hybridizes under stringent conditions)
And a first coding sequence comprising a polynucleotide that encodes a polypeptide having a function that allows the fusion protein to be expressed as a soluble protein when expressed as a fusion protein with the target protein; 3) An expression vector containing at least one restriction enzyme site into which a second coding sequence containing a polynucleotide encoding the target protein can be inserted. The vector according to claim 12, wherein the polypeptide represented by the formula (Z) _n is a polypeptide represented by (Z) ₂ . The polypeptide represented by the formula (Z) ₂ is:
(E) a polypeptide consisting of the amino acid sequence of SEQ ID NO: 3,
(F) When the amino acid sequence of SEQ ID NO: 3 comprises an amino acid sequence in which one or more amino acids are deleted, substituted, inserted and / or added, and is expressed as a fusion protein with the target protein, A polypeptide having a function capable of expressing a fusion protein as a soluble protein,
(G) The fusion protein is expressed as a soluble protein when it consists of an amino acid sequence having 90% or more identity to the amino acid sequence of SEQ ID NO: 3 and is expressed as a fusion protein with the target protein. And (h) an amino acid sequence encoded by a polynucleotide that hybridizes under stringent conditions with a polynucleotide consisting of a base sequence complementary to the base sequence of SEQ ID NO: 4, and The vector according to claim 13, which is a polypeptide selected from the group consisting of polypeptides having a function capable of being expressed as a soluble protein when expressed as a fusion protein with a target protein.   The vector according to any one of claims 12 to 14, wherein the promoter sequence capable of inducing expression is a promoter sequence capable of inducing expression at a low temperature.   The vector according to claim 15, wherein the promoter sequence capable of inducing expression at a low temperature is a cold shock gene promoter sequence.   The vector according to claim 16, wherein the promoter sequence of the cold shock gene is a promoter sequence of E. coli cold shock gene.   The vector according to claim 17, wherein the promoter sequence of the E. coli cold shock gene is a promoter sequence of the E. coli cold shock gene cspA, cspB, cspG, cspI or csdA.   19. The coding sequence according to any one of claims 12 to 18, further comprising a coding sequence containing a polynucleotide encoding a cleavable linker peptide between the first coding sequence and the second coding sequence. vector.   The vector according to claim 19, wherein the cleavable linker peptide is a linker peptide having a protease cleavage site.   21. The vector according to any one of claims 12 to 20, further comprising a coding sequence containing a polynucleotide encoding an amino acid sequence for purification on the 5 'side of the first coding sequence.   The vector according to claim 21, wherein the amino acid sequence for purification is a histidine tag sequence. (1) Formula (Z) _n
(In the formula, n represents an integer of 1 to 5, and Z represents a polypeptide selected from the group consisting of the following (a) to (d):
(A) a polypeptide comprising the amino acid sequence of SEQ ID NO: 1,
(B) a polypeptide comprising an amino acid sequence in which one or more amino acids are deleted, substituted, inserted and / or added in the amino acid sequence of SEQ ID NO: 1;
(C) a polypeptide comprising an amino acid sequence having 90% or more identity to the amino acid sequence of SEQ ID NO: 1, and (d) a polynucleotide comprising a base sequence complementary to the base sequence of SEQ ID NO: 2. A polypeptide comprising an amino acid sequence encoded by a polynucleotide that hybridizes under stringent conditions)
And a first amino acid sequence containing the amino acid sequence of a polypeptide having a function capable of being expressed as a soluble protein when expressed as a fusion protein with a target protein; and (2) A fusion protein comprising a second amino acid sequence containing the amino acid sequence of the target protein and capable of being expressed as a soluble protein. The fusion protein according to claim 23, wherein the polypeptide represented by the formula (Z) _n is a polypeptide represented by (Z) ₂ . The polypeptide represented by the formula (Z) ₂ is:
(E) a polypeptide consisting of the amino acid sequence of SEQ ID NO: 3,
(F) When the amino acid sequence of SEQ ID NO: 3 comprises an amino acid sequence in which one or more amino acids are deleted, substituted, inserted and / or added, and is expressed as a fusion protein with the target protein, A polypeptide having a function capable of expressing a fusion protein as a soluble protein,
(G) The fusion protein is expressed as a soluble protein when it consists of an amino acid sequence having 90% or more identity to the amino acid sequence of SEQ ID NO: 3 and is expressed as a fusion protein with the target protein. And (h) an amino acid sequence encoded by a polynucleotide that hybridizes under stringent conditions with a polynucleotide consisting of a base sequence complementary to the base sequence of SEQ ID NO: 4, and The fusion protein according to claim 24, which is a polypeptide selected from the group consisting of polypeptides having a function capable of being expressed as a soluble protein when expressed as a fusion protein with a target protein.   The fusion protein according to any one of claims 23 to 25, wherein the target protein is any one selected from the group consisting of apoaequorin, Gaussia luciferase and ebyl luciferase.   27. The fusion protein according to any one of claims 23 to 26, further comprising an amino acid sequence containing a cleavable linker peptide amino acid sequence between the first amino acid sequence and the second amino acid sequence. .   28. The fusion protein according to claim 27, wherein the cleavable linker peptide is a linker peptide having a protease cleavage site.   The fusion protein according to any one of claims 23 to 28, further comprising an amino acid sequence for purification on the amino terminal side of the first amino acid sequence.   30. The fusion protein according to claim 29, wherein the amino acid sequence for purification is a histidine tag sequence. Formula (Z) _n- L-X
(Wherein n represents an integer of 1 to 5; L represents a cleavable linker peptide; Z represents a polypeptide selected from the group consisting of the following (a) to (d):
(A) a polypeptide comprising the amino acid sequence of SEQ ID NO: 1,
(B) a polypeptide comprising an amino acid sequence in which one or more amino acids are deleted, substituted, inserted and / or added in the amino acid sequence of SEQ ID NO: 1;
(C) a polypeptide comprising an amino acid sequence having 90% or more identity to the amino acid sequence of SEQ ID NO: 1, and (d) a polynucleotide comprising a base sequence complementary to the base sequence of SEQ ID NO: 2. A polypeptide comprising an amino acid sequence encoded by a polynucleotide that hybridizes under stringent conditions; X represents the amino acid sequence of the target protein)
A fusion protein that can be expressed as a soluble protein.   32. The fusion protein according to claim 31, wherein the target protein is one selected from the group consisting of apoaequorin, Gaussia luciferase and ebyl luciferase.   A polynucleotide comprising a polynucleotide encoding the fusion protein according to any one of claims 23 to 32.   34. The polynucleotide of claim 33, which is DNA. (1) a promoter sequence that can induce expression;
(2) Formula (Z) _n
(In the formula, n represents an integer of 1 to 5, and Z represents a polypeptide selected from the group consisting of the following (a) to (d):
(A) a polypeptide comprising the amino acid sequence of SEQ ID NO: 1,
(B) a polypeptide comprising an amino acid sequence in which one or more amino acids are deleted, substituted, inserted and / or added in the amino acid sequence of SEQ ID NO: 1;
(C) a polypeptide comprising an amino acid sequence having 90% or more identity to the amino acid sequence of SEQ ID NO: 1, and (d) a polynucleotide comprising a base sequence complementary to the base sequence of SEQ ID NO: 2. A polypeptide comprising an amino acid sequence encoded by a polynucleotide that hybridizes under stringent conditions)
And a first coding sequence comprising a polynucleotide that encodes a polypeptide having a function of allowing the fusion protein to be expressed as a soluble protein when expressed as a fusion protein with the target protein; 3) A method for producing the target protein as a soluble protein, comprising expressing the protein using an expression vector containing a second coding sequence containing a polynucleotide encoding the target protein. 36. The method according to claim 35, wherein the polypeptide represented by the formula (Z) _n is a polypeptide represented by (Z) ₂ . The polypeptide represented by the formula (Z) ₂ is:
(E) a polypeptide consisting of the amino acid sequence of SEQ ID NO: 3,
(F) When the amino acid sequence of SEQ ID NO: 3 comprises an amino acid sequence in which one or more amino acids are deleted, substituted, inserted and / or added, and is expressed as a fusion protein with the target protein, A polypeptide having a function capable of expressing a fusion protein as a soluble protein,
(G) When the amino acid sequence has an amino acid sequence having 90% or more identity to the amino acid sequence of SEQ ID NO: 3 and is expressed as a fusion protein with the target protein, the fusion protein is expressed as a soluble protein. And (h) an amino acid sequence encoded by a polynucleotide that hybridizes under stringent conditions with a polynucleotide consisting of a base sequence complementary to the base sequence of SEQ ID NO: 4, and 37. The method according to claim 36, wherein when expressed as a fusion protein with a target protein, the fusion protein is a polypeptide selected from the group consisting of polypeptides having a function capable of being expressed as a soluble protein.   The method according to any one of claims 35 to 37, wherein the promoter sequence capable of inducing expression is a promoter sequence capable of inducing expression at a low temperature.   The method according to claim 38, wherein the promoter sequence capable of inducing expression at a low temperature is a cold shock gene promoter sequence.   40. The method of claim 39, wherein the cold shock gene promoter sequence is an E. coli cold shock gene promoter sequence.   41. The method of claim 40, wherein the promoter sequence of the E. coli cold shock gene is the promoter sequence of the E. coli cold shock gene cspA, cspB, cspG, cspI or csdA.   The coding sequence according to any one of claims 35 to 41, further comprising a coding sequence containing a polynucleotide encoding a cleavable linker peptide between the first coding sequence and the second coding sequence. Method.   43. The method of claim 42, wherein the cleavable linker peptide is a linker peptide having a protease cleavage site.   44. The method according to any one of claims 35 to 43, further comprising a coding sequence containing a polynucleotide encoding an amino acid sequence for purification on the 5 'side of the first coding sequence.   45. The method of claim 44, wherein the amino acid sequence for purification is a histidine tag sequence.

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