JP2007312677A - New endoglycoceramidase - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an endoglycoceramidase having a substrate specificity of acting on a glycolipid of which bond between sugar chain and ceramide is constituted by a β-galactoside bond, and expected to be utilized in the fields of glycolipid analysis, diagnosis, medicine, cosmetic, food, feed, agrochemical, environment, detergent, organic chemical, fiber, etc. <P>SOLUTION: It is possible to sever sugar chains from all of the glycolipids by a combination of an enzyme produced by Rhodococcusequi M-750 with previously obtained ganglio-based, globo-based and lacto-based enzymes acting on the glycolipids. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a novel endoglycoceramidase. The present invention also provides a novel endoglycoceramidase gene. The endoglycoceramidase of the present invention acts on glycosphingolipids and can cleave β-galactoside bonds between sugar and ceramide. The present invention is useful in fields related to glycolipids and sugar chains.

  Glycosphingolipid is an amphiphilic compound composed of a sugar chain exhibiting hydrophilicity and a ceramide exhibiting hydrophobicity. Glycosphingolipid is a major component of the cell membrane, intercellular recognition, involvement in differentiation and development, acts as a receptor for hormones, bacteria and bacterial toxins (Non-patent Document 1), cholesterol and other sphingolipids, and Src It is thought that microdomains are formed together with family kinases and G-proteins to control information transmission between cells and within cells (Non-patent Document 2).

Endoglycoceramidase (hereinafter sometimes referred to as EGCase) is an enzyme that specifically hydrolyzes glycoside bonds between sugar and ceramide of glycosphingolipids. It was first discovered from the culture supernatant of the actinomycete Rhodococcus sp. Strain G-74-2 (Non-patent Document 3, Patent Document 1). In addition, two types of EGCase contained in the culture supernatant of M-750, which is a mutant of Rhodococcus sp. Strain G-74-2, were purified, and various properties were examined (Non-patent Document 4). In addition, organisms such as leech (Non-patent document 5), earthworm (Non-patent document 6), shimizu (Non-patent document 7), jellyfish (Non-patent document 8), hydra (Non-patent document 9) also have EGCase activity. It was found. EGCase is a very useful enzyme as a tool for analyzing the structure and function of glycolipids because EGCase can be released without destroying the structure of sugar chains or ceramides.

Recently, the EGCase gene was cloned from the genomic DNA of Rhodococcus sp. M-777, which is a mutant of Rhodococcus sp. Strain G-74-2 (Non-patent Document 10). In the deduced amino acid sequence, an amino acid thought to be an active site of family A cellulose (endo-1,4-β-glucanase) called NEP sequence consisting of asparagine, glutamic acid and proline was conserved. As a result of creating a mutant in which glutamic acid in the NEP sequence was changed to aspartic acid or glutamine by introducing point mutations, the activity was greatly reduced (Non-patent Document 11). This indicates that glutamic acid in the NEP sequence is particularly important for the enzyme activity of EGCase.

The EGCase of jellyfish and hydra has also been cloned (Non-patent Documents 8 and 8). These EGCases have an optimum pH of 3.0 and an acidic range, and have a feature that they act well on polysialogangliosides. Moreover, it was confirmed that NEP sequences also exist in these EGCases. In situ hybridization using hydra reveals that EGCase is highly expressed in digestive cells and plays an important role in the catabolic pathway of glycolipids taken up by phagocytosis (Non-Patent Document 9). . It has been found that jellyfish EGCase catalyzes not only a hydrolysis reaction but also a sugar transfer reaction and a sugar condensation reaction (Non-patent Document 12).

  All of the EGCases described above specifically act on glycolipid bonds between sugar chains and ceramides, that is, glycolipids where the reducing end of the sugar chain starts with glucose.

JP 62-122587 (Japanese Patent Publication No. 7-89914) Hakomori, S. (1981) Annu. Rev. Biochem. 50, 733-764 Hakomori, S., Hanada, K., Iwabuchi, K., Yamamura, S., and Prinetti, A. (1998) Glycobiology 8, xi-xviii Ito, M., and Yamagata, T. (1986) J. Biol. Chem. 261, 14278-14282 Ito, M., and Yamagata, T. (1989) J. Biol. Chem. 264, 9510-9519 Zhou, B., Li, S.-C., Laine, R. A., Huang, R. T. C., and Li, Y.-T. (1989) J. Biol. Chem. 205, 729-735 Li, Y.-T., Ishikawa, Y., and Li, S.-C. (1987) Biochem. Bipphys. Res. Commun. 149, 162-172 Basu, S. S., Dastgheib-Hosseini, S., Hoover, G., Li, Z., and Basu, S. (1994) Anal. Biochem. 222, 270-274 Horibata, Y., Okino N., Ichinose, S., Omori, A., amd Ito M. (2000) J. Biol. Chem. 275, 31297-31304 Horibata, Y., Sakaguchi, K., Okino, N., Iida, H., Inagaki, M., Fujisawa, T., Hama, Y., and Ito, M. (2004) J. Biol. Chem. 279 , 33379-33389 Izu, H., Izumi, Y., Kurome, Y., Sano, M., Kondo, A., Kato, I., and Ito, M. (1997) J. Biol. Chem. 272, 19846-19850 Sakaguchi, K., Okino, N., Izu, H., and Ito, M. (1999) Biochem. Bipphys. Res. Commun. 260, 89-93 Horibata, Y., Higashi, H., and Ito, M. (2001) J. Biochem. 130, 263-268

The present inventors have studied on elucidation of biological functions of sugar chains and sphingolipids. Then, a novel endoglycoceramidase was found in the culture supernatant of the actinomycete Rhodococcus equi M-750, and its gene cloning, expression in Escherichia coli, and various properties thereof were examined, thereby completing the present invention.

I. EGCase gene:
The present invention relates to a novel EGCase-encoding gene and a homolog thereof, that is, a polynucleotide containing the following (a), (b), (c), (d), (e), (f) or (g) I will provide a:
(A) a polynucleotide comprising the entire nucleotide sequence of SEQ ID NO: 15 or a part containing at least the ORF portion;
(B) a polynucleotide encoding a protein that hybridizes under stringent conditions with a polynucleotide comprising a base sequence complementary to the base sequence of the polynucleotide described in (a) and has endoglycoceramidase (EGCase) activity nucleotide;
(C) It encodes a protein having a base sequence in which one or more bases are substituted, deleted, inserted and / or added in the base sequence of the polynucleotide described in (a) and having endoglycoceramidase activity A polynucleotide;
(D) a polynucleotide encoding a protein having at least 80% identity with the base sequence of the polynucleotide described in (a) and having endoglycoceramidase activity;
(E) a polynucleotide encoding a protein comprising a part of the amino acid sequence set forth in SEQ ID NO: 16 or a part containing at least the signal sequence portion;
(F) a polynucleotide encoding a protein comprising an amino acid sequence in which one or more amino acids are substituted, deleted, inserted and / or added in the amino acid sequence of the protein according to (e) and having endoglycoceramidase activity ;
(G) A polynucleotide encoding a protein comprising an amino acid sequence having at least 80% identity with the amino acid sequence of the protein described in (e) and having endoglycoceramidase activity.

  The “stringent conditions” as used in the present invention refers to the conditions of 6M urea, 0.4% SDS, 0.5 × SSC or a hybridization condition equivalent thereto, unless otherwise specified. May be applied under conditions of higher stringency, for example, 6M urea, 0.4% SDS, 0.1 × SSC or equivalent hybridization conditions. Under each condition, the temperature can be about 40 ° C. or higher, and if higher stringency conditions are required, for example, about 50 ° C. or about 65 ° C. may be used.

  Further, in the present invention, the number of nucleotides to be substituted when “base sequence in which one or more bases are substituted, deleted, inserted and / or added” is encoded by the polynucleotide comprising the base sequence. The number of proteins is not particularly limited as long as the protein has a desired function, but if it is a substitution that encodes an amino acid sequence having the same or similar properties, such as 1 to 9, or about 1 to 4, an even larger number Can be substituted. In the present invention, the number of amino acids to be substituted when “an amino acid sequence in which one or more bases are substituted, deleted, inserted, and / or added” is the number of amino acids to be substituted, and the protein having the amino acid sequence has a desired function. Although there is no particular limitation as long as it has, there are more substitutions as long as it is 1 to 9 or 1 to 4 or a substitution that encodes the same or similar amino acid sequence sell. Means for preparing a polynucleotide according to such a base sequence or amino acid sequence are well known to those skilled in the art.

  In the present invention, the nucleotide sequence described in SEQ ID NO: 15 is highly identical to a part of the entire nucleotide sequence or at least an ORF portion (the portion having a length of 1464 bases in positions 52 to 1515 in SEQ ID NO: 15). And a polynucleotide encoding a protein having EGCase. With respect to the base sequence, high identity refers to sequence identity of at least 50% or more, preferably 70% or more, more preferably 80% or more, even more preferably 90% or more, and most preferably 95% or more. Further, the present invention encodes a protein having an EGCase activity, comprising an amino acid sequence having high identity with the entire amino acid sequence shown in SEQ ID NO: 16 or at least a part including a portion excluding the signal sequence. Polynucleotides are included. With respect to amino acid sequences, high identity refers to sequence identity of at least 50% or more, preferably 70% or more, more preferably 80% or more, even more preferably 90% or more, and most preferably 95% or more. The identity of the amino acid sequence set forth in SEQ ID NO: 16 with the known amino acid sequence of EGCase is shown in FIG.

  Search / analysis relating to the identity (sometimes referred to as homology) of a polynucleotide sequence or amino acid sequence uses algorithms or programs (for example, DNASIS software, BLAST, CLUSTAL W, JALVIEW, etc.) well known to those skilled in the art. (Refer to the examples in the book). Those skilled in the art can appropriately set parameters when using a program, and the default parameters of each program may be used. Specific techniques for these analysis methods are also well known to those skilled in the art.

The polynucleotide of the present invention can be obtained from a natural product using a hybridization technique, a polymerase chain reaction (PCR) technique or the like. Specifically, genomic DNA (gDNA) is prepared from a bacterium belonging to the genus Rhodococcus (preferably Rhodococcus equi , more preferably Rhodococcus equi M-750 strain), or total RNA is prepared from the bacterium. Synthesize cDNA by reverse transcription. A full-length polynucleotide of the present invention can be obtained from gDNA or cDNA by designing and utilizing an appropriate partial base sequence of the EGCase of the present invention as a probe or primer.

The polynucleotide of the present invention includes DNA and RNA, and the DNA includes genomic DNA, cDNA and chemically synthesized DNA. DNA can be single-stranded DNA and double-stranded DNA.
The polynucleotide of the present invention is preferably derived from a bacterium belonging to the genus Rhodococcus (preferably Rhodococcus equi , more preferably Rhodococcus equi M-750 strain).

  The present invention also provides a recombinant vector containing the polynucleotide of the present invention and a transformant transformed with the recombinant vector. The present invention further provides a transformation method comprising the step of transforming a host (fungus, animal cell, plant cell, eg, E. coli) using the polynucleotide of the present invention.

  The vector into which the polynucleotide of the present invention is inserted is not particularly limited as long as the insert can be expressed in the host, and the vector is usually induced by a promoter sequence, terminator sequence, or external stimulus. A sequence for expressing an insert, a sequence recognized by a restriction enzyme for inserting a target gene, and a sequence encoding a marker for selecting a transformant. Methods known to those skilled in the art can be applied to the preparation of the recombinant vector and the transformation method using the recombinant vector.

II. Novel enzyme proteins:
The present invention also provides a protein encoded by the polynucleotide of the present invention or a homologue thereof, ie, the following protein (e ′), (f ′) or (g ′):
(E ′) a protein comprising a part of the amino acid sequence set forth in SEQ ID NO: 16 or a part including at least the signal sequence portion;
(F ′) a protein comprising an amino acid sequence in which one or more amino acids are substituted, deleted, inserted and / or added in the amino acid sequence of the protein according to (e ′) and having endoglycoceramidase activity;
(G ′) A protein comprising an amino acid sequence having at least 80% identity with the amino acid sequence of the protein described in (e ′) and having endoglycoceramidase activity.

Such proteins are also hydrolases that have the following properties:
(A) acting on glycosphingolipids and hydrolytically cleaving the bond between sugar or sugar chain and ceramide to produce sugar or sugar chain and ceramide;
(A) A glycosphingolipid having a β-galactosylceramide bond can be hydrolyzed, but a glycosphingolipid having a β-glucoside bond is not degraded;
(C) can act at 37 ° C;
(D) The optimum pH is 5.5 to 6.0; and (e) the molecular weight is about 54 kDa (measured by SDS-PAGE. In this specification, when referring to molecular weight, unless otherwise specified) , Means the value measured by SDS-PAGE).

Such a protein or hydrolase is also an endoglycoceramidase having a molecular weight of about 54 kDa produced by a bacterium belonging to the genus Rhodococcus (preferably Rhodococcus equi , more preferably Rhodococcus equi M-750). The actinomycete Rhodococcus equi M-750 was isolated as a mutant strain of Rhodococcus sp. G-74-2, but has been deposited at the Patent Organism Depositary under the receipt number: FERM AP-20926.

[Enzymatic properties of EGCase]
The enzymological properties of the endoglycoceramidase (EGCase) of the present invention are described below.
(1) Action The EGCase of the present invention acts on a glycosphingolipid and can hydrolytically cleave the sugar-ceramide bond.

(2) Substrate specificity Acts on glycosphingolipids having β-galactosylceramide bonds and can be hydrolyzed. Under the conditions shown in the examples of the present specification, glycosphingolipids having β-glucosylceramide bonds did not act. Moreover, under the conditions shown in the examples of the present specification, even a glycosphingolipid having a β-galactoside bond did not act on ganglio-based GM4 and sulfatide.

On the other hand, it can act on cerebroside bound with galactose and ceramide. Therefore, it can be said that it has exo-type activity against cerebroside.
It can also act on psychosine.

  The specificity for the ceramide moiety in the substrate appears to be low, including a ceramide moiety consisting of fatty acid residues 2-hydroxy 24: 0 and sphingoid residues phytospingosine, CDS, CTS, CTeS derived from fungi, and It can act on both TSA-derived TGCs, including a ceramide moiety composed of C16: 0 fatty acid residues and d18: 1 sphingosine residues.

  The specificity for a saccharide that directly binds to ceramide in the substrate is high, and it acts on TGC under the conditions shown in the examples of the present specification, but differs from TGC only in that the sugar that directly binds is glucose. -4 did not work.

(3) Optimum conditions The present inventors examined the optimum temperature of the EGCase of the present invention in the range of 10 to 80 ° C. As a result, the strongest activity was observed around 40 ° C. (data not shown). The EGCase of the present invention can act well around 37 ° C. The optimum pH is around 5.5-6.0.

Activity can be significantly increased with 0.1% Triton X-100 and Lubrol PX. In addition, an activator protein derived from Rhodococcus sp. That activates conventional EGCase can also activate the EGCase of the present invention.

With respect to the metal ions in the conditions shown in the examples herein, the activity is totally abolished by Hg ²⁺ addition, about 50% for Fe ^3+, Zn ^2+, reduction of Cu ²⁺ in about 90% active It was observed. Other metal ions and EDTA had no significant effect on rEGCase activity.

Km determined by Hanes-Wools plots was 0.43 mM, Vmax was 87.8 pmol / min, Kcat was 800 min ⁻¹ , and Kcat / Km was 1860.5 min ⁻¹ · mM ⁻¹ .
(4) Glycotransfer Reaction The EGCase of the present invention can also catalyze a transglycosylation reaction to 1-alkanol. In particular, under the conditions shown in the examples of the present specification, the sugar transfer from TGC to methanol, 1-hexanol and 1-octanol was catalyzed with high efficiency.

  The EGCase of the present invention can also accept a fluorescently labeled ceramide in the transglycosylation reaction.

[EGCase production method]
The EGCase of the present invention can be purified from the culture supernatant of a bacterium belonging to the genus Rhodococcus (preferably Rhodococcus equi , more preferably Rhodococcus equi M-750) by the following procedure.
(1) The culture supernatant is precipitated with 80% ammonium sulfate, and the precipitate is suspended in a buffer (for example, 20 mM sodium acetate, pH 6.0 plus 0.1% Lubrol PX).
(2) The suspension is applied to a hydrophobic column, and a surfactant (for example, 1% Lubrol PX) having an effective elution concentration is added to a buffer solution (for example, the above 20 mM sodium acetate, pH 6.0, the same applies hereinafter). Elute with added one and collect fractions with TGC degradation activity.
(3) The active fraction is applied to a weak anion exchange column and eluted with a buffer solution to which a salt (for example, 1M NaCl) having an effective elution concentration is added, and a fraction having TGC decomposition activity is recovered.
(4) A divalent metal ion (for example, Cu ²⁺ ion) was chelated to the active fraction, applied to a chelating hydrophobic column, and an elution effective concentration salt (for example, 2M NH ₄ Cl) was added to the buffer solution. Elute with water and collect the active fraction.
(5) Desalt the active fraction. For example, it is applied to a hydrophobic column and eluted with a buffer solution containing an elution effective concentration of a surfactant (for example, 0.5% Lubrol PX), and the active fraction is recovered.
(6) Apply the active fraction to a weak anion exchange column and use a gradient solvent to separate EGCase that degrades TGC and conventional EGCase that degrades GM1a. By this step, EGCase that degrades TGC and conventional EGCase that degrades GM1a can be separated. For example, by applying a gradient (0-20% / 20 minutes) with the above buffer and its buffer containing 1 M NaCl, followed by running a 20% mixture for 40 minutes.
(7) If desired, the active fraction is further applied to a strong anion exchange column equilibrated with a buffer, and a gradient solvent (for example, 0-20% / 20 min, 20-60 using a mixture of the above-mentioned buffers) is used. % / 250 min) to collect the active fraction. This is a refined product.

The EGCase of the present invention can also be produced by a transformant using the gene of the present invention. In the above-described method using a Rhodococcus genus, since the amount of EGCase secretion is extremely low, the method using this transformant is beneficial. Methods of transformation suitable for use with a particular host are well known to those skilled in the art.

III. Utilization of EGCase The present invention provides an EGCase that acts on a glycolipid (gala glycolipid) composed of a β-galactoside bond between the sugar chain and the ceramide. In combination with enzymes that act on glycolipids, globo- and lactoglycosides, sugar chains can be cleaved from all glycolipids. Further, the EGCase of the present invention can be applied to the structure analysis and functional analysis of a gala-series glycolipid and a specific detection method for a gala-series glycolipid. In addition, gala-series glycolipids are present in pathogenic fungi and are suspected to be associated with pathogenicity. However, gala-series glycolipids may be used to classify pathogenic fungi. Therefore, the present invention provides a method for analyzing and detecting a gala-series glycolipid, characterized by using the protein, hydrolase, or EGCase of the present invention.

  The EGCase of the present invention catalyzes not only hydrolysis but also transglycosylation activity. The transglycosylation reaction to 1-alkanol showed much higher activity than the conventional EGCase. In addition, sugar transfer to fluorescently labeled ceramide was also confirmed. Fluorescently labeled glycolipids can be very useful tools for analyzing glycolipid functions. It can also contribute to the construction of a highly sensitive assay system for enzymes that act on glycolipids. Therefore, the present invention also provides a glycolipid treatment method, a sugar chain treatment method, and a glycolipid production method characterized by using the protein, hydrolase, or EGCase of the present invention. Processing includes synthesis, decomposition, and transfer.

The EGCase of the present invention showed a strong activity on both the fungal-derived glycolipid and the Sazae-derived glycolipid. Ceramide, a glycolipid derived from fungus, is composed of 2-hydroxy 24: 0 fatty acid and phytospingosine sphingoid (Aoki, K., Uchiyama, R., Yamauchi, S., Katayama, T., Itonori, S. Sugita, M., Hada, N., Yamada-Hada, Junko., Takeda, T., Kumagai, H., and Yamamoto, K. (2004) J. Biol. Chem . 279, 32028-32034). On the other hand, ceramide, a glycolipid derived from Sazae, has a fatty acid of C16: 0 and is composed of d18: 1 sphingosine (Matsubara, T., and Hayashi, A. (1981) J. Biochem . 89, 645-650). Thus, although the ceramide structures are completely different, both showed strong hydrolysis activity, and thus the substrate specificity for the kind of ceramide seems to be wide. In contrast, the recognition mechanism for the reducing end of a sugar chain is very strict. In particular, the presence or absence of a hydrolysis reaction for TGC and GL-4 in Table 2 should be noted. The only difference between these glycolipids is that the reducing end of the constituent sugar is galactose or glucose. All other glycan linkages are similarly β 1-6 (Kubo, H., Jiang, GJ, Morita, M., Matsubara, T., and Hoshi, M. (1992) J. Biochem . 111, 726-731). Furthermore, the EGCase of the present invention was a glycolipid having a β-galactoside bond, but had no effect on GM4 and sulfatide. It may not act on acidic glycolipids.

  In addition, despite the fact that the substrate specificities are completely different as shown above, in the EGCase reported heretofore, all amino acids that constitute the active site were also conserved in the EGCase of the present invention. It is very important in the field of enzyme research to elucidate what amino acid and what three-dimensional structure difference is sensed by crystallization of the EGCase of the present invention and three-dimensional structure analysis by NMR. .

The EGCase of the present invention also activates a conventional EGCase, an activator protein derived from Rhodococcus sp. (Ito, M., Ikegami, Y., and Yamagata, T. (1991) J. Biol. Chem. 266, 7916-7926) also acted on the EGCase of the present invention (data not shown). If an activator protein is used, a surfactant necessary for the activity of EGCase becomes unnecessary. That is, it is considered that the effect of the EGCase of the present invention on living mold and echinococcus can be verified.

On the other hand, the EGCase of the present invention showed a strong activity on the fungus-derived glycolipid, but in previous reports, the fungus, parasite Echinococcus (Persat, F., Bouhours, JF, Mojon, M., and Petavy, AF (1992) J. Biol. Chem. 267, 8764-8796) and other organisms have been found to contain glycolipids composed of β-galactoside bonds and having two or more sugar chains as biological components. Yes. Moldy mildew causes mucormycosis, a serious illness that can lead to death, in some people with reduced immunity. Echinococcus causes a disease called echinococcosis that can cause liver dysfunction and can be fatal if progressed. As shown in the examples of the present specification, the EGCase of the present invention acts on the fungal glycolipid. On the other hand, there are few glycolipids having a β-galactoside bond and consisting of two or more sugar chains in the human body. Therefore, the EGCase of the present invention can be expected to be an ideal therapeutic agent that acts only on the fungal and echinocox glycolipids, kills them, and has little effect on the living body.

  The EGCase of the present invention is expected to be used in fields such as diagnostics, pharmaceuticals, cosmetics, foods, feeds, agricultural chemicals, the environment, detergents, organic chemicals, and textiles.

IV. Abbreviations The following abbreviations are used in this specification.
bp: base pair
Cer: ceramide
CDS: ceramide disaccharide
CTS: ceramide trisaccharide
CTeS: ceramide tetrasaccharide
EGCase: endoglycoceramidase
Gal: galactose
GalCer: galactosylceramide
Glc: glucose
GlcCer: glucosylceramide
GSL (s): glycosphingolipid (s)
LacCer: lactosylceramide
NBD: 4-nitrobenzo-2oxa-1,3-diazole
NeuAC: N-acetylneuraminic acid
ORF: open reading frame
PAGE: polyacrylamide gel electrophoresis
PCR: polymerase chain reaction
TBS: tris buffered seline
TGC: neogalatriaosylceramide (trigalactosylceramide)
TLC: thin-layer chromatography

  According to the present invention, there is provided EGCase and its gene having substrate specificity that acts on a glycolipid composed of β-galactoside bond between sugar chain and ceramide. Until now, there was no report that an enzyme having such substrate specificity was isolated and purified. The present invention provides the first confirmation that this type of enzyme exists. The EGCase and its gene provided by the present invention are expected to be used as useful tools that contribute to further development of glycolipid research.

[Materials and methods]
material
LA Taq, TAKARA LA PCR In vitro Cloning Kit was purchased from Takara Bio Inc., plasmid pET22b from Novagen, restriction enzyme and Ligation-Convenience Kit from Nippon Gene, and silica gel 60TLC plate from Merck.

TGC was prepared from Sazae by a conventionally reported method (supra Matsubara et al. (1981)). GT1b (product name ganglioside GT1b, derived from bovine brain), GD1a (product name ganglioside GD1a, derived from bovine brain), GM1a (product name ganglioside GM1a, derived from bovine brain), Gb ₄ Cer (product name globotetraosylceramide, porcine erythrocyte) Origin), Gb ₃ Cer (product name globotriaosylceramide, porcine erythrocyte origin), LacCer (product name lactosylceramide, derived from bovine), GalCer (product name galactosylceramide, derived from bovine spinal cord), GlcCer (product name glucosylceramide) , Human spleen (derived from Gaucher disease) was purchased from Wako Pure Chemical Industries, Ltd.

GM4 was prepared from red sea bream (Chisada, S., Horibata, Y., Hama, Y., Inagaki, M., Furuya, N., Okino, N., and Ito, M. (2005) Biochem. Biophys. Res . . Commun. 333, 367-73), GL-4 was the one that was prepared by the method of supra Kubo et al. (1992) our generous gift from Keio University Faculty of Science and Technology life information Department of star professor. CDS, CTS, and CTeS were prepared by Prof. Yamamoto from the Graduate School of Life Sciences, Kyoto University, prepared by Aoki et al. (2004). Triton X-100 and Lubrol PX were purchased from Nacalai Tesque. C12-NBD-Cer (NBD-C12: 0 / d18: 1) is a condensation reaction with SCDase (Tani, M., Kita, K., Komori, H., Nakagawa, T., and Ito, M. (1998 ) Anal. Biochem . 263, 183-188). The structure of glycolipid is as shown in Table 2. The ceramide part of GM4 is mixed with fatty acid residues such as 2-hydroxy 24: 1, 2-hydroxy 22: 0, 2-hydroxy 23: 0, etc. The sphingoid residue consists of d18: 1.

The strain actinomycete Rhodococcus equi M-750 was isolated as a mutant of Rhodococcus sp. G-74-2 (Ito, M. and Yamagata, TJ Biol. Chem. 264, 9510-9519). The bacterium was cultured by a conventional method (Non-Patent Document 4) and genomic DNA was extracted (Saito, H., and Kimura, H. (1963) Biochem. Biophys. Acta . 72, 619-629) . E. coli DH5α and BL21 (λDE3) were purchased from Takara Bio Inc.

Purification and purification were performed according to the following procedure.
(1) The culture supernatant (1.8 L) is precipitated with 80% ammonium sulfate, centrifuged at 8000 rpm, 30 min, 4 ° C., and the precipitate is added to 170 mL of buffer A (20 mM sodium acetate, pH 6.0, 0.1% In which Lubrol PX was added).
(2) This was applied to a hydrophobic column Octyl-Sepharose CL-4B (200 ml, Amersham Bioscience, Uppsala, Sweden) equilibrated with buffer A, and eluted with 1% rubrol PX in buffer A. Fractions having a degradation activity (270 ml, 100 mg) were collected.
(3) The active fraction is applied to a weak anion exchange column DEAE-Sepharose FF (70 ml, Amersham Bioscience) equilibrated with buffer A, and eluted with 1M NaCl added to buffer A. Fractions (75 ml, 31 mg) were collected.
(4) The active fraction was applied to a Chelating-Sepharose FF column (30 ml, Amersham Bioscience), which was chelated with Cu ²⁺ ions, equilibrated with buffer A added with 2M NaCl, and buffer A with 2M NH ₄ The active fraction (175 ml, 12 mg) was collected by elution with the addition of Cl.
(5) In order to desalinate the active fraction, it was applied to a hydrophobic column Octyl-Sepharose FF (70 ml, Amersham Bioscience) and eluted with buffer A supplemented with 0.5% Lubrol PX. 110 ml) was recovered.
(6) DEAE-5PW (7 ml, Tosoh Co., Tokyo, Japan), which is a weak anion exchange column in which the active fraction is equilibrated with buffer A, contains 1M NaCl in buffer A (buffer B ) With a gradient (0-20% / 20 minutes) followed by 20% buffer B for 40 minutes. Through this process, EGCase that degrades TGC and conventional EGCase that degrades GM1a could be separated. The active fraction (110 ml, 5.6 mg) was collected.
(7) Apply the active fraction to a strong anion exchange column POROS HQ (10 ml, PE-Biosystems, USA) equilibrated with buffer A. Gradient with buffer B (0-20% 20 minutes, 20-60% 250 minutes) ) To collect the active fraction (80 ml, 0.016 mg). This was a refined product.

Cleveland method samples determined purification partial amino acid sequence (Cleveland, DW (1977) J. Biol. Chem. 252, 1102-1106) by, digested with V ₈ and lysylendopeptidase AP-1 (Wako), blotted onto a PVDF membrane And stained with Coomassie Brilliant Blue. The stained spot was cut out and subjected to a protein sequencer (Procise 49X-cLC; PE-Biosystems) to determine the amino acid sequence.

Acquisition of partial gene sequence by PCR In order to acquire a new EGCase gene, degenerate primers were designed from the partial amino acid sequence of the purified enzyme. C-1479-S1 (5'-GGNGCNAAYGTNAAYGG-3 'SEQ ID NO: 1) as sense primer, C-1485-A1 (5'-TARAANGCYTGRAANGC-3' SEQ ID NO: 2) as antisense primer, Rhodococcus equi M PCR was performed using -750 genomic DNA as a template. PCR was performed with Gene Tamp PCR system 9700 (PE Biosystems) using LA Taq for 35 cycles (98 ^° C. 10 seconds, annealing temperature 50 ^° C. 1 minute, extension temperature 72 ^° C. 30 seconds). The amplified product was subcloned into pGEM T-eazy vector (Promega), and the nucleotide sequence was determined.

DNA sequence and DNA handling method The nucleotide sequence was determined by the dideoxy method using BigDye Terminater Cycle Sequencing Ready Reaction Kit (PE Biosystems) and a DNA sequencer (model 377A; Applied Biosystems). DNA extraction from agarose gel, plasmid extraction from bacterial cells, etc. are conventional methods (Sambrook, H., Fritsch, EF, and Maniatis, T. (1989) A Laboratory Manual, 2nd. Edn., Cold Spring Harbor Laboratory Press , Cold Spring Harbor, NY).

TAKARA LA PCR in which the acquisition genomic DNA of full-length gene was digested to completion with BamH1, corresponding thereto Ligation was performed with the cassette attached to the in vitro Cloning Kit. Using this as a template, a primer complementary to the cassette and a 5 ′ end-determining primer EGCBamA1 (5′-GTTGGACGCGTAGTCGTTG-3 ′ SEQ ID NO: 3) and a 3 ′ end-determining primer EGCBamS1 ( PCR was performed with GeneAmp PCR system 9700 using 5′-TCAGATCGGACGCTTCTACC-3 ′ SEQ ID NO: 4) for 25 cycles (94 ^° C. 30 seconds, annealing temperature 56 ^° C. 30 seconds, extension temperature 72 ^° C. 1 minute), The amplified product was subcloned into the pGEM T-eazy vector, and the nucleotide sequence was determined.

Analysis of base and amino acid sequences Base and amino acid sequences were analyzed by DNASIS software (Hitachi Software Engineering). Searching for amino acid sequences with identity is BLAST (Altschul, SF, Gish, W., Miller, W., Myers, EW, and Lipman, DJ (1990) J. Mol. Biol. 215, 403-410). went. The alignment of amino acid sequences is CLUSTAL W (Thompson, JD, Higgins, DG, and Gibson, TJ (1994) Nucleic Acids Res . 22, 4673-4680) and JALVIEW (Clamp, M., Cuff, J., Searle, SM, and Barton, GJ (2004) Bioinformatics. 20, 426-427).

Creating an expression construct
PCR was performed using rEGC3-S2 (5′- GGAAGCTT TCTCCGGTGCCGTCGGAC-3 ′ SEQ ID NO: 5) as a sense primer and rEGC3-HisA (5′- GGCGGCCGC GAGTGTGGTGACCGAGTAC-3 ′ SEQ ID NO: 6) as an antisense primer. rEGC3-S2 contains a HindIII site as shown by underline, and rEGC3-HisA contains a NotI site shown by underline. PCR was performed with LA Taq using GeneAmp PCR system 9700 for 25 cycles (98 ^° C. for 1 minute, annealing temperature of 56 ^° C. for 30 seconds, extension temperature of 72 ^° C. for 2 minutes). The amplified product was treated with HindIII and NotI, and ligated to pET22b treated with the same restriction enzymes to obtain an expression construct pETrEGC.

Recombinant enzyme expression and purification
E. coli BL21 (λDE3) transformed with pETrEGC was cultured with shaking at 37 ^° C. for 12 hours in 5 ml of Luria-Bertani (LB (+)) medium containing 100 μg / ml ampicillin. Transfer to 200 ml of LB (+) medium, shake culture until OD 600 reaches about 0.5, and add IPTG (isopropyl β-D-thiogalactoside) to a final concentration of 0.1 mM to induce expression. The mixture was further cultured with shaking for 5 hours. The culture is centrifuged at 8000 g for 10 minutes, and the cell pellet is completely suspended in 100 ml of 30 mM Tris-HCl pH 8 20% sucrose, and 60 μl of 0.5 M EDTA, pH 8 (final concentration 1 mM) And allowed to gently stir at room temperature for 10 minutes. 4 ° C., and centrifuged at 10,000 × g for 10 minutes to remove condensed bacteria, the supernatant to 5 mM MgSO ₄ 100 ml of ice-cold completely suspend the pellet gently 10 of this cell suspension in ice Stir for minutes. Centrifugation was performed at 4 ° C. and 10,000 × g for 10 minutes to precipitate cells subjected to osmotic shock, and the supernatant was collected, which was used as a periplasm fraction. The periplasmic fraction was applied to a HiTrap Chelating HP column chelated with Ni ²⁺ and washed with 20 mM phosphate buffer pH 7.4 containing 0.5 M NaCl, 0.2% Triton X-100 and 25 mM imidazole. The recombinant enzyme was eluted with 20 mM phosphate buffer pH 7.4 containing 0.5 M NaCl, 0.2% Triton X-100 and 100 mM imidazole. This was dialyzed against 50 mM sodium acetate buffer pH 5.5. The amount of protein was measured by the BCA method using BSA as a standard.

Enzyme assay The reaction system of the enzyme assay was constructed with 10 nmol glycolipid, 0.2% Triton X-100, 50 mM sodium acetate buffer containing an appropriate amount of enzyme, pH 5.5, 20 μl. The subsequent reaction was performed at 37 ^° C.

The reaction was stopped after 5 minutes in a boiling water bath. The reaction solution was dried by a speed bag, dissolved in 10 μl of methanol, applied to a TLC plate, and developed with chloroform / methanol / 0.02% CaCl ₂ = 2/3/1. Glycolipids and oligosaccharides were colored with orcinol sulfate, and the color intensity was measured with a Shimadzu CS-9300 chromatographic scanner in reflectance mode set at 540 nm. The hydrolysis rate was calculated by the following formula.

  One unit (U) was defined as the amount of enzyme that hydrolyzes 1 μmol of TGC in 1 minute.

Examination of various properties of recombinant enzymes To determine the optimum pH, using TGC as a substrate, 50 mM sodium acetate buffer (pH range 3-6), 50 mM phosphate buffer (pH range 6-8), and A reaction system was constructed. To investigate the effects of metal ions, various metal ions (Fe ³⁺ , Fe ²⁺ , Zn ²⁺ , Mg ²⁺ , Ca ²⁺ , Co ²⁺ , Na ⁺ , Cu ²⁺ , Co ²⁺ , Mn ^{2 +} , Hg ²⁺ ) and EDTA were added at 5 mM each. In order to investigate the substrate specificity, GT1b, GD1a, GM1a, Gb4Cer, Gb3Cer, LacCer, GalCer, GlcCer, GM4, GL-4, CDS, CTS, and CTeS were used as substrates, respectively.

SDS-PAGE and Western blotting
SDS-PAGE was performed according to the Laemmli method. Proteins were separated on 12.5% SDS-PAGE and stained with Coomassie Brilliant Blue. Low-moleculer-mass SDS-PAGE calibration kit (Amersham Pharmacia Biotech) was used as a standard. For Western blotting, proteins were separated by 12.5% SDS-PAGE and transferred to a nitrocellulose membrane using a semi-dry blotter (Bio-Rad). The membrane was blocked with TBS containing 3% skim milk for 1 hour, washed 3 times with TBS containing 0.02% Tween 20, and then reacted with anti-His antibody (Invitrogen) for 2 hours at room temperature. This was washed 3 times with TBS containing 0.02% Tween 20, and then reacted with a horseradish peroxidase-conjugated anti-mouse IgG antibody for 1 hour and a half at room temperature. This was washed three times with TBS containing 0.02% Tween 20, and then developed with a peroxidase-stain kit (Nacalai Tesque).

The reaction system for synthesizing alkyl glycosides by transglycosylation is 20 mM 50 mg sodium acetate buffer, pH 5.5, containing 10 nmol glycolipid, 0.2% Triton X-100, 0.5 mU enzyme, 20% 1-alkanol. Constructed on a μl scale. This was reacted at 37 ^° C. for 1 hour, dried by speed back, dissolved in methanol, applied to a TLC plate, and developed with chloroform / methanol / 0.02% CaCl 2 = 5/4/1. Glycolipids, oligosaccharides, and alkyl glucosides were colored with orcinol sulfate, and the color intensity was measured with a Shimadzu CS-9300 chromatographic scanner in the reflectance mode set to 540 nm.

The reaction system for the synthesis of fluorescently labeled glycolipid consists of 10 mMol glycolipid, 0.2% Triton X-100, 0.5 mU enzyme, 50 mM sodium acetate buffer containing 1 nmol C12-NBD-Cer, pH 5.5 Was constructed on a 20 μl scale. Moreover, the system which added acetone to this reaction system was constructed. These were reacted at 37 ^° C. for 1 hour, dried by speed back, dissolved in methanol, applied to a TLC plate, and developed with chloroform / methanol / 0.02% CaCl 2 = 5/4/1. The fluorescent label was detected by UV irradiation. Glycolipids and free oligosaccharides were detected with orcinol sulfate.

〔result〕
Amino Acid Sequences Amino acid sequences were performed using purified samples identified as single bands on SDS-PAGE by various column chromatography. As a result, partial amino acid sequences (SEQ ID NOs: 7 to 14) shown in Table 1 were obtained.

Cloning of gene PCR with degenerate primers C-1479-S1 and C-1485-A1 designed from the amino acid sequences obtained from peptide fragments C-1479 and C-1485 gave a specific amplification product of 431 bp . Peptide fragments C-1479, C-1482, and C-1485 were confirmed in the sequence of this amplified product. In order to obtain the full length of the gene, primers EGCBamA1 and EGCBamS1 were newly designed from this gene partial sequence, and TAKARA LA PCR The full length of the gene was obtained by PCR using in vitro Cloning Kit (FIG. 1).

Deduced amino acid sequence of novel EGCase The nucleotide sequence (SEQ ID NO: 15) and deduced amino acid sequence (SEQ ID NO: 16) of novel EGCase are shown in FIG. 1A. The novel EGCase gene consists of a 1464 bp ORF and encodes 488 amino acids. From the deduced amino acid sequence, the molecular weight was calculated to be 52299 and the pI was 4.28. Hydrophobic plot (Kyte, J., and Doolittle, RF (1982) J. Mol. Biol. 157, 105-132) confirmed 22 highly hydrophobic amino acid residues that appear to be signal sequences at the N-terminus (Figure 1B). Excluding the signal sequence, the molecular weight was calculated to be 50186.

The novel EGCase showed 26% identity with Rhodococcus EGCase, 28% with jellyfish EGCase, and 28% with hydra EGCase at the amino acid level (FIG. 2, SEQ ID NOs: 17 to 19). Interestingly, the amino acids constituting the active site of EGCase reported so far were conserved in the novel EGCase, even though the substrate specificity was different. Of these, NEP (Non-Patent Document 11), which is particularly important, is the 234th glutamic acid and the 341st glutamic acid in the sequence, which function as an acid-base catalyst group and a nucleophilic group, respectively. In addition, amino acids thought to constitute the active site of EGCase, such as 95 arginine, 137 histidine, 304 histidine, and 306 tyrosine, were also conserved in the new EGCase.

Expression and purification The expression construct pETrEGC was used to transform E. coli BL21 (λDE3) to prepare its periplasmic fraction, which was applied to a HiTrap Chelating HP column. When purified recombinant novel EGCase (rEGCase) was subjected to SDS-PAGE, a single protein band estimated to have a molecular weight of 54 kDa was detected (FIG. 3A). This protein band was confirmed to be derived from the expression construct by Western blotting using His-Tag (FIG. 3B). rEGCase hydrolyzed TGC with β-galactoside bond as a substrate into oligosaccharide and ceramide, but did not act on GM1 with β-glucoside bond (Fig. 4). On the other hand, conventional EGCase derived from Rhodococcus sp. Did not act on TGC and showed strong hydrolysis activity on GM1. This indicates that the enzyme that was successfully cloned in this study is completely different from the previously reported EGCase. The specific activity of rEGCase was 6 U / mg and the yield was 4 mg per 1 L culture.

Various properties
Various properties of rEGCase were examined using TGC as a substrate. The optimum pH was 5.5-6.0 (Figure 5A). When the influence of the surfactant was examined, it was confirmed that the activity was significantly increased by 0.1% Triton X-100 and Lubrol PX (FIG. 5B). As for the influence of metal ions, the activity disappeared completely by the addition of Hg ²⁺ , and the activity decreased about 50% for Fe ^{3+ and} 90% for Zn ²⁺ and Cu ²⁺ (FIG. 5C). Other metal ions and EDTA had no significant effect on rEGCase activity. The Km determined by Hanes-Wools plots was 0.43 mM, Vmax was 87.8 pmol / min, Kcat was 800 min ⁻¹ , and Kcat / Km was 1860.5 min ⁻¹ · mM ⁻¹ .

Substrate specificity
When rEGCase was allowed to act on glycolipids CDS, CTS, and CTeS having a β-galactoside bond derived from fungi, a hydrolysis reaction was shown as in TGC (FIG. 6, Table 2). In addition, although it was weak in activity, it was found to act on GalCer and psychosine (FIG. 6, Table 2). On the other hand, glycolipids having β-glucoside bonds did not show any activity despite being reacted for a long time (Table 2).

Glycotransfer reaction to 1-alkanol
When rEGCase and TGC were reacted in the presence of 1-alkanol, a new band with different Rf values was detected on the TLC plate for both TGC-derived oligosaccharide and TGC (FIG. 7). This is considered to be caused by the transfer of TGC-derived oligosaccharide to 1-alkanol. It was found that rEGCase catalyzes not only hydrolysis but also transglycosylation. In particular, methanol, 1-hexanol, and 1-octanol were transferred with a high conversion rate of 45 to 47% (Table 3). In contrast, 1-propanol was observed not only for transglycosylation but also for inhibition of hydrolysis.

Glycotransfer reaction to fluorescently labeled ceramide.
Fluorescently labeled glycolipids are very useful for functional analysis of glycolipids and construction of highly sensitive assay systems for enzymes that act on glycolipids. We tested whether rEGCase transglycosylation also accepts fluorescently labeled ceramide as an acceptor. As a result, in the reaction system in which rEGCase, TGC, C12-NBD-Cer, and acetone were added at 15%, a band of C12-NBD-TGC that was thought to have occurred as a result of the transglycosylation reaction was confirmed (FIG. 8).

The base and deduced amino acid sequence (A) of the EGCase gene of the present invention and a hydrophobicity plot. (A) The deduced amino acid sequence of the novel EGCase is shown by one letter at the bottom of the base sequence. Amino acid sequences were numbered sequentially, starting with valine as 1. The termination codon is indicated by an asterisk. The signal sequence is shown in bold letters. The underlined portion shows a partial amino acid sequence obtained by the amino acid sequence. (B) Hydrophobic plot of the deduced amino acid sequence performed by Kyte and Doolittle method. Alignment of EGCase of the present invention and deduced amino acid sequence of EGCase cloned so far. Alignment of EGCase of the present invention and deduced amino acid sequences of known EGCase of Rhodococcus , jellyfish and hydra using CLUSTAL W and JALVIEW . Amino acids that showed identity were indicated with asterisks, and amino acids with similar chemical properties were indicated with dots. Gaps in the sequence are indicated by horizontal lines. In conventional EGCase, 234th glutamic acid and 341st glutamic acid (both indicated by black arrows), which are considered to function as acid-base catalysts and nucleophilic groups, respectively, are also conserved in the new EGCase. It was. In addition, five amino acids (indicated by white arrows) constituting the active site of EGCase were also confirmed. Recombinant EGCase (rEGCase) SDS-PAGE and Western blotting. (A) After SDS-PAGE, staining with Coomassie Brilliant Blue. (B) Results of Western blotting using anti-His-Tag antibody. lane 1: cytoplasmic fraction, lane 2: periplasmic fraction, lane 3: purified recombinant enzyme Confirmation of rEGCase activity. (A) Results of analysis of rEGCase activity by TLC. lane 1: GM1, lane 2: EGCase I + GM1, lane 3: rEGCase + GM1, lane 4: TGC, lane 5: EGCase I + TGC, lane 6: rEGCase + TGC (B) rEGCase TGC (●) and GM1a Time course for (□). Various properties of rEGCase. (A) The optimum pH was determined using TGC as a substrate. ◇, Sodium acetate buffer, pH 3.0-6.0; Black square, Phosphate buffer, pH 6.0-8.0 (B) Results of examining the effect of surfactant. TGC was used as a substrate. ◆, Triton X-100; □, Lubrol PX; △, TDC. (C) Effects of metal ions and EDTA. Action on glyceride-derived glycolipids. Reaction of 20 nm of 50 mM sodium acetate buffer pH 5.5 containing 10 nmol of glycerin-derived glycolipids, 0.2% Triton X-100, 0.5 mU recombinant EGCase in 20 ml Was confirmed by TLC. Arrows indicate free oligosaccharides. lane 1: Gal-Cer, lane 2: GalCer + rEGCase, lane 3: CDS, lane 4: CDS + rEGCase, 5: CTS, 6: CTS + rEGCase, lane 7: CTeS, lane 8: CTeS + rEGCase The EGCase of the present invention transfers TGC oligosaccharides to various 1-alkanols. The reaction system contains 10 nmol glycolipid, 0.2% Triton X-100, 0.5 mU enzyme, 20% 1-alkanol. A 50 mM sodium acetate buffer, pH 5.5 was constructed in 20 ml. This was reacted at 37 ^° C. for 1 hour, developed with TLC, and developed with orcinol sulfate. lane 1: TGC, lane 2: TGC + rEGCase, lane 3: TGC + rEGCase + MeOH, lane 4: TGC + rEGCase + EtOH, lane 5: TGC + rEGCase + 1-propanol, lane 6: TGC + rEGCase + 1-butanol , lane 7: TGC + rEGCase + isoamyl alcohol, lane 8: TGC + rEGCase + 1-hexanol, lane 9: TGC + rEGCase + 1-octanol. The EGCase of the present invention also accepts fluorescently labeled ceramide in the transglycosylation reaction. 50 mM acetic acid containing 10 nmol glycolipid, 0.2% Triton X-100, 0.5 mU enzyme, 1 nmol C12-NBD-Cer Sodium buffer, pH 5.5 was constructed with 20 ml. In lane 4, this was reacted with acetone for 1 hour at 37 ^° C. After developing with TLC, (A) detected the reaction product by UV irradiation, and (B) detected it with orcinol sulfate. lane 1: TGC, lane 2: TGC + rEGCase, lane 3: TGC + rEGCase + C12-NBD-Cer, lane 4: TGC + rEGCase + C12-NBD-Cer + 15% acetone, lane 5: C12-NBD-Cer , lane 6: TGC + C12-NBD-Cer

Claims (12)

A polynucleotide containing the following (a), (b), (c), (d), (e), (f) or (g):
(A) a polynucleotide comprising the entire nucleotide sequence of SEQ ID NO: 15 or a part containing at least the ORF portion;
(B) a polynucleotide that hybridizes under stringent conditions with a polynucleotide comprising a base sequence complementary to the base sequence of the polynucleotide according to (a) and encodes a protein having endoglycoceramidase activity;
(C) It encodes a protein having a base sequence in which one or more bases are substituted, deleted, inserted and / or added in the base sequence of the polynucleotide described in (a) and having endoglycoceramidase activity A polynucleotide;
(D) a polynucleotide encoding a protein having at least 80% identity with the base sequence of the polynucleotide described in (a) and having endoglycoceramidase activity;
(E) a polynucleotide encoding a protein comprising a part of the amino acid sequence set forth in SEQ ID NO: 16 or a part containing at least the signal sequence portion;
(F) a polynucleotide encoding a protein comprising an amino acid sequence in which one or more amino acids are substituted, deleted, inserted and / or added in the amino acid sequence of the protein according to (e) and having endoglycoceramidase activity ;
(G) A polynucleotide encoding a protein comprising an amino acid sequence having at least 80% identity with the amino acid sequence of the protein described in (e) and having endoglycoceramidase activity. 2. The polynucleotide according to claim 1, which is derived from a bacterium belonging to the genus Rhodococcus . The following protein (e ′), (f ′) or (g ′):
(E ′) a protein comprising a part of the amino acid sequence set forth in SEQ ID NO: 16 or a part including at least the signal sequence portion;
(F ′) a protein comprising an amino acid sequence in which one or more amino acids are substituted, deleted, inserted and / or added in the amino acid sequence of the protein according to (e ′) and having endoglycoceramidase activity;
(G ′) A protein comprising an amino acid sequence having at least 80% identity with the amino acid sequence of the protein described in (e ′) and having endoglycoceramidase activity. A hydrolase with the following properties:
(A) acting on glycosphingolipids and hydrolytically cleaving the bond between sugar or sugar chain and ceramide to produce sugar or sugar chain and ceramide;
(A) A glycosphingolipid having a β-galactosylceramide bond can be hydrolyzed, but a glycosphingolipid having a β-glucosylceramide bond is not degraded;
(C) can act at 37 ° C;
(D) The optimum pH is 5.5 to 6.0; and (e) the molecular weight is about 54 kDa. Acting on glycosphingolipids obtained from the culture supernatant of bacteria belonging to the genus Rhodococcus , hydrolytically cleaving the bond between sugar or sugar chain and ceramide to produce sugar or sugar chain and ceramide A possible endoglycoceramidase with a molecular weight of about 54 kDa. Bacteria belonging to the genus Rhodococcus is a Rhodococcus equi M-750 (FERM AP -20926), endoglycoceramidase of claim 5. A method for analyzing or detecting a gala glycolipid, comprising using the protein according to claim 3, the hydrolase according to claim 4, or the endoglycoceramidase according to claim 5 or 6. A method for treating a glycolipid or a sugar chain, comprising using the protein according to claim 3, the hydrolase according to claim 4, or the endoglycoceramidase according to claim 5 or 6. A method for producing a glycolipid, comprising using the protein according to claim 3, the hydrolase according to claim 4, or the endoglycoceramidase according to claim 5 or 6. A vector comprising the polynucleotide according to claim 1. A transformed bacterium transformed with the vector according to claim 10. A protein according to claim 3, a hydrolase according to claim 4, or an endoglycoceramidase according to claim 5 or 6, wherein the transformant according to claim 11 is used. Method.