EP0293391A4 - Cloned streptococcal genes encoding protein g and their use to construct recombinant microorganisms to produce protein g. - Google Patents

Abstract

A cloned gene encoding protein G, or functionally active portions thereof, vectors containing the cloned gene, and microorganisms transformed by those vectors.

Description

CLONED STREPTOCOCCAL GENES ENCODING PROTEIN G

AND THEIR USE TO CONSTRUCT RECOMBINANT

MICROORGANISMS TO PRODUCE PROTEIN G

Cross-Reference to Related Applications

This application is a continuation-in-part of U.S. Application Serial No. 854,887, filed April 23, 1986, which is a continuation-in-part of U.S. Application Serial No. 829,354, filed February 14, 1986.

Technical Field

This present invention relates to the cloning of genes which specify the biosynthesis of Streptococcus Protein G and the use of organisms transformed with the cloned genes to produce Protein G and Protein G-like polypeptides.

Background Art There has been a growing interest in recent years in bacterial F_c receptors, molecules that bind to antibodies through a nonimmune mechanism. This binding is not to the antigen recognition site, which is located in the F_{a b} portion of the antibody molecule, but to the F_c portion of the antibody. The F_c region is common to many types of antibodies, thus bacterial F_c receptors can bind to many types of antibodies. This property makes bacterial F_c receptors useful in a number of immunochemical applications.

Bacterial F_c receptors have a number of useful or potentially useful applications, primarily in the detection of antibodies, the purification of antibodies and the treatment of diseases. The detection of antibodies is required in several phases of laboratory research in immunology, including the screening of hybridoma clones for the secretion of specific monoclonal antibodies, the measurement of the immune response of an immunized animal, and the quantitation of antigens by competitive binding assays. Methods for detecting antibodies using bacterial F_c receptors have been found to be more sensitive and less prone to interference and high background signals than other detection methods [Boyle, M.D.P., Biotechnigues 2:334-340 (1984)].

F_c receptors also are useful in purifying antibodies to be used in the purification of protein drugs and as therapeutics. Although a number of methods are known, a popular method involves the use of affinity chromatography on columns of immobilized bacterial F_c receptors. This method is preferred because the columns can be reused many times, thus lowering the expense of purification.

A number of potential clinical uses of bacterial F_c receptors are currently under investigation. They include passing plasma over extracorporeal columns of immobilized F_c receptors, then reinfusing the treated plasma. See, for example, Tenan, D.S., et al., N. Eng. J. Med. 305:1195-1200 (1981).

The best known bacterial F_c receptor is Protein A of Staphylococcus aureus. which binds to the constant F_c domain of immunoglobulin IgG. Other bacterial F_c receptors also have been identified. One of these is known as Protein G of Group G streptococci. Although Protein G is analogous to Protein A, Protein G has several important advantages. For example. Protein G binds to all subclasses of human IgG, whereas Protein A does not bind to the IgG3 subclass [Reis, K. J. et al. J. Immunol. H2.:3098-3102 (1984)]. Protein G also is specific for IgG and does not cross-react with huma antibodies of type IgA and IgM as Protein A does. [Myhre, E.B. and Kronvall, G. "Immunoglobulin Specificities of Defined Types of Streptococcal Ig Receptors" In: Basic Concepts of Streptococci and Streptococcal Diseases; J.E. Holm and P. Christensen, eds.; Redbook, Ltd., Chertsey, Surrey; pp. 209-210 (1983)]. In addition. Protein G binds to certain animal IgGs to which Protein A binds weakly or not at all. These include bovine, ovine, and caprine IgGl and several subclasses of equine IgG (Reis, K. J. et al., supra). Protein G also has been found superior to Protein A in binding to several subclasses of murine monoclonal antibodie [Bjorck, L. and Kronvall, G. J. Immunol. 133:969-97 (1984)]. For these reasons. Protein G is likely to becom the bacterial F_c receptor of choice in a variety of applica tions.

Currently, Protein G is obtained by investigators for study by purification from Streptococcal strains which naturally produce it. For example, Streptococcal cells have been treated with proteolytic enzymes (e.g., papain or trypsin) to solubilize the Protein G (which is a cell wall protein), followed by known protein purification procedure (e.g., ion exchange chromatography, gel filtration, and affinity chromatography) to further purify the Protein G (European Patent Application, Publication Number 0 131 142).

Given the advantages, uses and potential uses of Protein G, it would be desirable to be able to produce the protein using recombinant DNA methodology. Accordingly, it is an object of the present invention to clone the gene encoding Protein G and to produce Protein G by transforming a microbial host with the cloned gene and cultivating the host under Protein G-producing conditions.

Description of the Invention

The present invention provides a cloned gene encoding an F_c receptor protein having the IgG binding properties of Protein G. The gene is derived from a Streptococcus Sp., Lancefield Group G, strain and inserted onto a cloning vector. Cells of a prokaryotic organism which have been stably transformed with recombinant vectors are disclosed. One transformed strain comprises a first vector carrying the gene encoding a protein having the properties of Protein G and a second vector which does not contain the gene and acts as a cryptic helper plasmid to stably maintain the first vector in the host strain. Other transformants carry vectors in which the DNA insert comprising the gene encoding the Protein G protein has been modified such that a helper plasmid is no longer needed. The transformed strains are cultivated under Protein G-producing conditions.

The invention further provides the identification of the nucleotide sequence and amino acid sequence for the active binding site of the molecule. One gene cloned by the inventor contains two active sites. A second cloned gene contains three active sites.

The invention further provides for the production, using recombinant vectors, of Protein G-like polypeptides, the Protein G-like polypeptides containing one or more amino acid sequences which demonstrate the IgG-binding characteristics of Protein G. Brief Description of the Figures

Figure 1 is a diagram showing the salient features of plasmid pGX1066, a vector suitable for use in cloning a Protein G-encoding DNA fragment.

Figure 2 shows a partial restriction map of plasmid pGX4533, a recombinant plasmid vector containing a Protein G-encoding DNA fragment.

Figure 3 shows a DNA sequence for the Protein G gene, as well as the amino acid sequence encoded by the gene.

Figure 4 shows the restriction map of the cloned protein G gene and the repeating structure of its protein product responsible for IgG-binding.

Figure 5 shows the partial restriction map of mGX4547, a bacteriophage vector containing a Protein G-encoding fragment.

Figure 6 shows the partial restriction map of mGX7880, a bacteriophage vector which contains two complete copies of the B structure and lacks all amino acid sequences distal to B1 and B2.

Figure 7 shows a restriction map of plasmid pGX4582, a recombinant plasmid vector used to transform B. subtilis which contains a Protein G-encoding fragment.

Figure 8 shows the location of the active sites, B1 and B2, on Protein G as coded for by the cloned Protein G gene derived from streptococcus.

Figure 9 shows the DNA and amino acid sequences for the cloned Protein G gene derived from streptococcus. This gene codes for a Protein G containing three active sites.

Figure 10 shows the relationship between the repeating structures of the Protein G gene derived from strains GX805 and GX7809. Best Mode of Carrying Out the Invention

The present invention relates to cloned Protein G genes. A DNA fragment comprising a Protein G gene is isolated from a Streptococcus Sp., Lancefield Group G, strain and inserted into a cloning vector. Another aspect of the invention relates to production of Protein G by transforming host cells with a recombinant vector comprising a cloned Protein G gene and culturing the transformed cells under protein-producing conditions, whereupon Protein G is produced by the cells.

Yet another aspect of the invention is directed to production of a Protein G-like material, said material containing from one to twenty Protein G binding sites per molecule. This Protein G-like material has the formula:

-(-B-b-)_n-

wherein B is B1, B2 as shown in Figure 9 or a hybrid sequence comprising Bl and B2 which is designated B3, b is as shown in Figure 8, and n is from 1 to 20.

By the term "hybrid sequence" is intended DNA or amino acid sequences which contain portions of the respective sequences corresponding to B1 and B2 and which retain the immunoglobulin binding properties of Protein G. Such a hybrid sequence is shown in Figure 9 and is labeled B3. This hybrid sequence comprises the portion of B1 corresponding to the amino acid sequence 298-314 of B2 fused to the sequence 245-282 of B1. Thus, it is intended that all such hybrid sequences which retain the immunoglobulin binding properties of Protein G are within the scope of this invention.

Cloning of the Protein G gene and production of Protein G in bacterial hosts, such as E. coli or Bacillus subtilis, through recombinant DNA technology, the method of the present invention, provides a number of advantages over current methods for obtaining the protein. By the method of this invention, relatively high levels of microbial Protein G production can be obtained, the protein can be produced under conditions where it can be isolated more favorably, and the protein can be produced in a non-pathogenic host. The cloned gene may be inserted into various multicopy expression vectors to give enhanced levels of this valuable IgG-binding protein in cultured E. coli cells transformed with the recombinant expression vectors. Production of Protein G in E. coli or B. subtilis cells is preferable to cultivation of Protein G-producing Streptococcal strains, which are commonly pathogenic strains.

In addition, the proteolytic enzymes, such as papain and trypsin, which have been used to release Protein G from the cell wall of Streptococcal cells, may degrade the Protein G product. Thus, known methods of isolating Protein G from Streptococcal cells may produce low molecular weight degraded forms of Protein G.

The first step in the cloning of the Protein G gene, according to the present invention, is isolation of Streptococcal strains that produce Protein G. This may be done by assaying various strains for IgG binding activity using any suitable immunoassay technique. A technique used by the Applicant is the colony immunoassay described in detail in the examples section below. Strains found to have IgG-binding activity are next tested for the ability to bind IgG3 as well as unfractionated IgG, since the ability to bind IgG3 is a desired property associated with Protein G. A hemagglutination assay using red blood cells coated either with IgG3 or with unfractionated IgG (described in detail in the examples below) is a convenient method for identifying Protein G-producing strains. A known Protein A-producing strain, such as Staphylococcus aureus Cowan I [Sjoquist, J., Eur. J. Biochem.. 78: 471-490 (1977)], may be used as a control, since Protein A binds unfractionated IgG but not IgG3.

Chromosomal DNA is isolated from strains found to produce Protein G by cultivating the strains in a nutrient medium to a desired cell density, then lysing the cells by any of the conventional chemical, mechanical, and/or enzymatic methods known in the art. Conventional extraction and precipitation procedures are used to isolate the chromosomal DNA. Fragments of DNA of a suitable size for cloning are obtained by such known mechanical methods as sonication or high-speed stirring in a blender, or by enzymatic methods, such as partial digestion with DNAsel, which gives random fragments, or with restriction endonucleases, which cleave at specific sites.

The chromosomal DNA fragments then are inserted into a cloning vector. Any suitable plasmid or bacteriophage cloning vector may be used. For a vector to be suitable, it should have several useful properties. It should have an origin of replication that is functional in the intended microbial host cells, and a selective marker (such as an antibiotic resistance gene) to aid in identification of host cells that have been transformed with the vector. It should be able to accept inserted DNA fragments and still replicate normally. Preferably, the vector comprises one or more unique restriction endonuclease recognition sites at which DNA fragments can be inserted without destroying the vector's ability to replicate.

Suitable cloning vectors include phage derivatives such as lambda gtll [Young and Davis, Proc. Nat'l Acad. Sci. U.S.A., 80:1194-1198 (1983)], the various phage M13-derived vectors such as M13mp9 (commercially available from Bethesda Research Laboratories), plasmids such as pBR322, and many others [Old and Primrose, Principles of Gene Manipulation. 2nd. Ed., Univ. of Calif. Press, pgs. 32-35 and 46-47 (1981)]. The Applicant used a pBR322-derived plasmid vector pGX1066, shown in Figure 1.

The Streptococcal DNA is inserted into the cloning vector by such methods as homopolymeric tailing or by using linker molecules (Old and Primrose, supra at page 92). Advantageously, the vector is linearized with a restriction endonuclease, and the chromosomal DNA is also digested with a restriction endonuclease that produces DNA fragments that are ligatable to the ends of the linearized vector molecule. The Streptococcus-derived DNA fragments are thus advantageously inserted into the cloning vector in a standard reaction using the enzyme T4 DNA ligase.

Bacterial cells are transformed with the recombinant cloning vector, using standard procedures, and the bacterial colonies are screened for production of Protein G. Assays such as the colony immunoassay and the hemagglutination assay described in the examples below are suitable for identification of recombinant strains producing Protein G. As described more fully in example I below, the initial positive colony identified was unstable. Through purification procedures in which this clone underwent several rounds of restreaking, a derivative of the clone was obtained which appeared stable and produced Protein G. This strain was designated E. coli GX7820.

Plasmid DNA from this strain was isolated and then analyzed by restriction analysis followed by gel electrophoresis. It has been determined that the strain contains two plasmids. One, designated pGX1066X, appears to be approximately the same size as the pGX1066 cloning vector; the other, designated pGX4530, appears to be pGX1066 containing an 11 kilobase-pair (kbp) insert. Although the Applicant does not wish to be bound by a particular theory, it appears, as illustrated more fully in the examples, that pGX1066X is a "cryptic helper plasmid", a derivative of pGX1066 in which the ampicillin resistance gene is no longer intact. The original transformant strain probably contained pGX1066 and pGX4530, and was unstable because pGX4530 was lost from the cells due to lack of selective pressure to retain that plasmid when pGX1066 was present to provide ampicillin resistance. Once pGX1066X appeared, having a mutation that inactivated its ampicillin resistance gene, only those host cells which had retained pGX4530 (having an intact ampicillin resistance gene) could survive on the ampicillin plates. Plasmid pGX1066X is retained in the cells containing both plasmids, presumably because it serves to limit the copy number of pGX4530 in the cell. Plasmid pGX4530 alone is lethal to the host cells (see Example I), but the presence of pGX1066X in the same host cell reduces the copy number of pGX4530 to a tolerable level. The plasmids are from the same "incompatibility group", i.e., the plasmids compete with each other for maintenance in the cell, so that each plasmid limits the copy number of the other in the host cell. E. coli strain GX7820 has been deposited with the American Type Culture Collection in Rockville, Maryland, and given accession number 53460.

An E. coli strain was transformed with a mixture of the plasmids isolated from strain GX7820. The tranformation resulted in a number. of tiny, strongly positive colonies with a few (about 20%) resembling GX7820. From these tiny positive colonies have been isolated two stable variants which do not carry the helper plasmid and which are more strongly positive for Protein G than the original GX7820. One strain, designated GX7823, carries a plasmid (pGX4533) from which has been deleted a two kilobase pair (kbp) fragment of the insert in the pGX4530 plasmid. E. coli strain GX7823 has been deposited with the American Type Culture Collection in Rockville, Maryland and given accession number 53461. The other, designated GX7822, carries a plasmid which has acquired a three kbp insert of DNA within the original insert at a site very close to one end of the deletion in the plasmid carried by the GX7823 strain. The Protein G gene has been located on a 1.9 kilobase pair (kbp) fragment of the Streptococcal DNA insert on pGX4533.

To improve Protein G production levels, the cloned Protein G gene may be inserted into a variety of expression vectors. The expression vectors comprise "regulatory regions", which include DNA sequences necessary for gene expression, i.e., the transcription of DNA into mRNA followed by translation of the mRNA into the protein that the gene encodes. The Protein G gene may contain its natural expression signals, or those signals may be removed and the structural portion of the cloned Protein G gene (i.e., th protein-encoding portion of the gene) can be operably fused, in accordance with conventional methods, to other expression signals, contained in an expression vector, which are capable of directing the Protein G gene in the chosen host organism. For example, when the host microorganism is E. coli the expression vector may comprise such known regulatory regions as the trp promoter/operator, the lac promoter/operator, the bacteriophage lambda P_L promoter/operator, and many others.

In one embodiment of the invention, the expression vector further comprises a DNA sequence homologous to a region of the chromosome of the host microorganism. This construction permits linear integration of the vector into the host chromosome in the region of homology. An advantag to this method is that there is less likelihood of loss of the Protein G sequence from the host, due to negative selection favoring vector-free cells.

Protein G may be produced at high levels in bacterial cells transformed with such recombinant expression vectors. In addition, production of Protein G within the cell may be controlled by using promoter/operator systems which may be induced (to begin gene expression) at a desired cell density, or in which gene expression can be reversibly repressed until the cell density in a culture of recombinant bacterial cells has reached a desired level. The potentially negative effects on cell growth of production of a heterologous protein can thus be avoided.

Transformed cells containing a cloned Protein G gene are cultivated under protein-producing conditions such that Protein G is produced by the cells. Cultivation conditions, including large-scale fermentation procedures, are well known in the art. The cells may be cultivated under any physiologically-compatible conditions of pH and temperature, in any suitable nutrient medium containing assimilable sources of carbon, nitrogen and essential minerals that supports cell growth. Protein-producing cultivation conditions will vary according to the type of vector used to transform the host cells. For example, certain expression vectors comprise regulatory regions which require cell growth at certain temperatures, or addition of certain chemicals to the cell growth medium, to initiate the gene expression which results in production of Protein G. Thus, the term "protein producing conditions" as used herein is not meant to be limited to any one set of cultivation conditions.

Advantageously, the cloned gene is transferred to B. subtilis by methods previously applied to the gene encoding Protein A and described in commonly assigned United States Patent No. 4,617,266 (1986), incorporated herein by reference in its entirety. In accordance with these methods. Protein G can be synthesized in B. subtilis.

The functionally active portions of Protein G was localized to a repeating structure by examining the IgG-binding activity of protein produced by E. coli strains carrying modified forms of the cloned protein G gene. Thus, the invention also relates to a cloned gene which encodes one or more of the functionally active portions of Protein G and to the protein so produced which has the immunoglobulin binding properties of Protein G. The details of the identification and isolation of the gene coding for the active site of Protein G are set forth in Example III below. The DNA sequences, and the amino acid sequences encoded thereby, of two genes encoding, respectively, two and three active sites per Protein G molecule are set forth in Figures 8 and 9. With this information, it is now possible to produce Protein G-like molecules which contain multiple sites of Protein G activity. Synthetic genes may be constructed, utilizing known synthetic procedures, which code for from one to twenty or more active sites within a given amino acid sequence, thereby providing higher binding efficiency and capacity to the resulting material. A preferred Protein G-like material contains 1 to 10 active sites; a more preferred material contains 1 to 5 active sites.

Also within the scope of this invention are proteins having the immunoglobulin-binding properties of Protein G, further having deletions or substitutions of amino acids or additional amino acids at the amino or carboxyl terminus thereof.

Any suitable known method of protein purification may be used to recover and purify the Protein G from the host cells. The cells may be lysed, if necessary, using known chemical, physical, and/or enzymatic means. The Protein G then may be purified from the cell lysate using such standard procedures as adsorption to immobolized immunoglobulin, as described by Sjoquist, U.S. Patent No. 3,850,798 (1974), ion-exchange or gel chromatography, precipitation (e.g., with ammonium sulfate), dialysis, filtration, or a combination of these methods.

The following Examples are provided to illustrate the invention, and is not to be construed as limiting the scope of the invention.

EXAMPLE I

Cloning a Streptococcus Protein G Gene into E. coli

Streptococci of Lancefield group G were obtained from hospitals, and 11 independent isolate strains were derived from the clinical isolates. Each strain was assayed for ability to bind IgG using the following colony immunoassay procedure. The strains were streaked on L-Broth-agar plates which had been overlaid with a sheet of nitrocellulose and (top layer) a sheet of cellulose acetate ("immunoassay plates"). The plates were incubated at 37°C until bacterial colonies were visible on the cellulose acetate sheet.

The nitrocellulose sheets then were removed from the plates, and IgG-binding proteins were detected on the sheets using an immunochemical procedure, as follows. The sheets were first treated with bovine serum albumin (3.0% w/v in "Tris-saline", which comprises 0.01M Tris-HCl, pH 8.0, and 0.15M NaCl) to block nitrocellulose sites to minimize non-specific binding of antibodies to the nitrocellulose in subsequent steps. The sheets then were treated with normal rabbit serum (diluted 1:1000 in Tris-saline containing 3% w/v bovine serum albumin) for 1 hour at 23 *C, followed by peroxidase-conjugated goat anti-rabbit IgG (similarly diluted), and, finally, with 4-chloro-1-naphthol (0.6 mg/ml) and hydrogen peroxide (0.06% w/v in Tris-saline containing 0.2 volume methanol), washing the sheets with Tris-saline between incubation steps. Blue spots on the nitrocellulose sheet indicate the presence of IgG-binding protein, and the blue areas correspond to microbial colonies which produced the IgG-binding protein.

Nine of the strains were positive, i.e. were found to bind IgG, although to varying degrees. Several of the strains were next tested for ability to bind IgG3, using the following hemagglutination assay. Sheep red blood cells (RBC) (Cappel Laboratories, Malvern, Pennsylvania) were coated with immunoglobulin essentially as described by Adler and Adler [Meth. Enzvmol. 20:455-466 (1980)]. RBC were washed with phosphate-buffered saline (PBS, containing 8.4 g/l NaCl, 1.1 g/l Na₂HPO₄, and 0.27 g/l NaH₂PO₄) and treated for 15 min. at 37ºC with a solution of tannic acid at 2.5 mg/ml in PBS. Cells were recovered by centrifugation and resuspended in PBS containing, at 0.2 mg/ml, either (a) total human immunoglobulin G (available from Sigma Chemical Co; St. Louis, Mo.), (b) IgG3 myeloma protein or (c) PBS only. After incubation at 37ºC for 30 min, RBC were recovered by centrifugation and washed with PBS. For the agglutination assay, 50 ul of a 1% suspension of coated RBC were mixed with 50 ul of a test cell extract, diluted serially in PBS, in a conical well of a multiwell dish. Unagglutinated RBC settle to the bottom of the well and form a small pellet, while agglutinated RBC form a more diffuse precipitate on the walls of the well.

Each of the positive group G Streptococcal strains agglutinated IgG3-coated erythrocytes as efficiently as erythrocytes coated with unfractionated IgG, which is expected for Protein G-producing strains. In contrast, Staphylococcus aureus Cowan I cells, a strain which produces Protein A, agglutinated red blood cells coated with unfractionated IgG, but showed no activity toward IgG3-coated cells, as expected. None of the cells agglutinated red blood cells which had been incubated with PBS only, i.e., uncoated red blood cells.

The same hemagglutination assay then was performed on supernatant fractions and cell extracts from cultures of the Streptococcus isolates and the isolates appeared to have differing localization of the IgG-binding activity. In some strains the activity appeared to be predominantly cell-bound, in some it was found predominantly in the culture supernatant, and some strains were intermediate. Three strains, which had differing localization of the IgG-binding activity, were chosen as sources of DNA for cloning the Protein G gene.

Cells from each strain were cultivated in 250 mis. of Todd-Hewitt broth (commercially available from Fisher Scientific, Richmond, Va.) containing 20mM D,L-threonine. After 4 hours of cultivation, glycine was added to a final concentration in the culture medium of 5% (w/v). The cells were harvested by centrifugation after 5 hours of cultivation, when the cell density had reached an absorbance at 600nm of about 0.5 to 1.0. The cell pellets were washed with PBS and then frozen in liquid nitrogen and stored at -70ºC. After thawing, the cells were washed with, and then resuspended in, 10 mis of S7 medium [described by Vasantha and Freese, J. Bacteriology 144:1119-1125 (1980)] containing 0.5M sucrose, to which 200 ul of 5 mg/ml mutanolysin (commercially available from Sigma Chemical Co.) had been added. Following incubation at 37ºC for 45 minutes, the resulting protoplasts were pelleted by centrifugation, and then lysed osmotically by resuspension in a solution containing 100mM EDTA, pH 8.0, 150mM NaCl, and 0.5 mg/ml Proteinase K. Following incubation at 37ºC for 55 minutes, alpha-toluenesulfonyl fluoride (also called phenylmethanesulfonyl fluoride or PMSF, and available commercially, e.g. from Sigma) was added to a final concentration of 2mM, and the mixture was incubated at 70ºC for 15 minutes to inactivate the Proteinase K. The cell lysate was extracted three times with chloroform/isoamyl alcohol (24:1) to further remove proteins, and an equal volume of isopropanol was added to the aqueous phase to precipitate the DNA. The precipitated DNA was collected by winding on a spool, and then was washed with 70% ethanol and dried in vacuo.

The DNA pellets (from each of the 3 strains) were each resuspended in 0.5 ml of a 0.01M Tris-HCl (pH 7.8)/lmM EDTA/0.05 M NaCl solution. A portion of this isolated chromosomal DNA was partially digested with the restriction endonuclease Mbol (commercially available) by adding 2 units of Mbol to 25 ul of the resuspended DNA in 100 ul of a buffer containing 100 mM Tris-HCl, pH 7.8, 150 mM NaCl and 10mM MgCl₂. The reaction mixture was incubated at 37ºC for 13 minutes, then at 70ºC for 10 minutes. The digested DNA was subjected to electrophoresis on a 0.8% agarose gel for 15 hours at 0.35 volts/cm. The section of the gel containing DNA fragments between about 4 and 9 kilobase-pairs (kbp) in length was excised from the gel and crushed to aid in recovery of the DNA. An equal volume of H₂O-saturated phenol was added to the crushed gel portion, and the mixture was frozen at -70ºC for 1 hour. Without prior thawing, the mixture was centrifuged at room temperature for 15 minutes in an Eppendorf microfuge, and the aqueous phase was extracted twice with an equal volume of phenol and once with an equal volume of phenol/chloroform/isoamyl alcohol (25:24:1). The DNA was precipitated from the aqueous phase by adding 2.5 volumes of 95% ethanol and 30 ug glycogen as a carrier.

The cloning vector into which the chromosomal DNA fragments were inserted was plasmid pGX1066, shown in Figure 1. This plasmid comprises a bank of closely-spaced restriction endonuclease recognition sites useful for insertion of DNA fragments to be cloned. The bank of cloning sites is bordered by two transcription terminators. E. coli strain GX1186, which constitutes strain GX1170 transformed by plasmid pGX1066 has been deposited with the ATCC as No. 39955. 3 ug of plasmid pGX1066 DNA were digested with the restriction endonuclease BamHI (commercially available and used according to manufacturer's specifications.) The digested plasmid DNA then was treated with 1 unit calf intestine alkaline phosphatase, (obtained from Boehringer-Mannheim and used according to manufacturer's specifications) for 30 minutes at 37ºC. Following extraction of the reaction mixture with phenol/chloroform/isoamyl alcohol (25:24:1), the DNA was precipitated by adding 0.1 volume 2M sodium acetate, 10mM EDTA, and 2.5 volumes 95% ethanol and 10 ug glycogen as a carrier. 0.5 ug of the pGX1066 vector DNA (BamHI-digested and phosphatase-treated) then was ligated to 0.2 ug of the partially Mbol digested Streptococcus chromosomal DNA prepared above. The 10 ul reaction mixture contained 1 unit of T4 DNA ligase (commercially available and used according to manufacturer's instructions) and was incubated at 4ºC for 20 hours. E. coli SK2267 (F- gal thi Tl^r hsdR4 endA sbcB15, available from the E. coli Genetic Stock Center, Yale University, New Haven, Conn.) cells were made competent for transformation by standard calcium chloride treatment, and 0.25 ml of the competent cells then were mixed with 20 ul of the ligation mixture in a standard transformation procedure [Lederberg and Cohen, J. Bacteriol. 119:1072-1074 (1974)]. The cells then were pelleted by centrifugation and resuspended in 0.3 ml L Broth. 0.1 ml of cells then were plated on each of three L Broth-agar plates containing 100 ug/ml ampicillin, which had been overlaid with a sheet of nitroellulose and (top layer) a sheet of cellulose acetate (immunoassay plates). The plates were incubated at 37ºC until bacterial colonies were visible on the cellulose acetate sheet.

The nitrocellulose sheets then were removed from the plates, and IgG-binding proteins were detected on the sheets using the immunochemical procedure described above. The sheets were first treated with bovine serum albumin (3.0% w/v in tris-saline) to block nitrocellulose sites to minimize non-specific binding of antibodies to the nitrocellulose in subsequent steps. The sheets then were treated with normal rabbit serum, diluted 1:1000 in Tris-saline containing 3.0% w/v bovine serum albumin, for 1 hour at 23ºC, followed by peroxidase-conjugated goat anti-rabbit IgG (diluted similarly), and, finally, with 4-chloro-1-naphthol (0.6 mg/ml) and hydrogen peroxide (0.06% w/v in Tris-saline containing 0.2 vol. methanol), washing with tris-saline between incubation steps.

One positive colony was identified, and was located on a plate containing transformants derived from Streptococcus strain GX7809 (one of the three Streptococcus strains from which DNA was isolated for cloning.) The positive colony was streaked out on an immunoassay plate (containing 100 ug/ml ampicillin, as above) to obtain a purified transformant strain. The nitrocellulose sheet was processed as above, and only a few positives were, found among hundreds of negative colonies. It appeared that the original transformant was unstable, so the restreaking process was repeated, and only one positive was found among hundreds of negative colonies. Another round of restreaking produced a plate containing mostly positive colonies. One of the positive colonies, a derivative which was apparently more stable than the original positive transformant, was isolated and designated E. coli strain GX7820. Samples of E. coli GX7820 have been deposited at the American Type Culture Collection in Rockville, Maryland and given the accession number ATCC No. 53460.

In addition to the original positive colony, several small but strongly positive spots, which could not be correlated with any colony, were observed. These spots yielded no positive progeny on restreaking.

A standard procedure was used to isolate plasmid DNA from E. coli GX7820, and the plasmid DNA was analyzed by restriction analysis followed by gel electrophoresis. The strain was found to contain two types of plasmids. One plasmid (designated pGX1066X) appeared to be the same size as the pGX1066 cloning vector, while the other (designated pGX4530) apparently was pGX1066 containing an 11 kbp insert. Competent E. coli SK2267 cells then were retransformed with the mixture of plasmids isolated from GX7820, and transformants were selected on immunoassay plates containing 100 ug/ml ampicillin. Positive transformants of two types were obtained. A majority formed tiny, strongly positive colonies, most of which could not be propagated. A minority resembled GX7820 in being of more normal size and more easily propagatable. In order to clarify the cause of these results, competent E. coli SK2267 cells were also transformed with gel purified plasmids, as follows:

Transformation A: pGX4530 alone

Transformation B: pGX1066X alone

Transformation C: mixture of pGX4530 and pGX1066X

The results were as follows: Transformation A: tiny, strongly positive colonies, most of which could not be propagated.

Transformation B: no transformants

Transformation C: many tiny, strongly positive non-propagatable colonies (as in trans. A) with about 20% of the positives resembling GX7820, i.e. of normal size and propagatable.

Several of the tiny, strongly positive colonies were chosen from the retransformation plates above (i.e., the transformants resulting from transformation of E. coli with an unfractionated plasmid preparation derived from strain GX7820 comprising a mixture of pGX1066X arid pGX4530) and were restreaked to isolate propagatable strains. Plasmid DNA was isolated from two strains, and both were found to have lost the pGX1066X helper plasmid. One strain (designated E. coli GX7823) contained a plasmid pGX4533 in which a deletion of about 2 kbp had occurred in the 11 kbp insert found in pGX4530. Samples of E. coli GX7823 have been deposited at the American Type Culture Collection in Rockville, Maryland and given the accession number ATCC No. 53461. The second strain (designated E. coli GX7822) contained a plasmid pGX4532 which had acquired an additional 3 kbp of unidentified DNA inserted within the original 11 kbp insert, at a site very close to one end of the deletion in pGX4533.

The strains E. coli GX7823 (containing pGX4533) and E. coli GX7820 (containing pGX4530) were cultivated in L-Broth plus ampicillin. The cells were pelleted by centrifugation, lysed by incubating for 30 min at 37ºC in the presence of 0.5 mg/ml lysozyme in a buffer containing 50 mM EDTA, pH 8.0, and 2mM PMSF. Samples of the extracts were prepared for electrophoresis by heating for 5 min. at 100ºC in the buffer described by Studier [J. Mol. Biol. 19:237-248 [1973)], and the samples were subjected to electrophoresis on a 12.5% acryla mide-SDS gel as described by Studier, op. cit., to separate the proteins. A standard electrophoretic (Western Blotting) technique was used to transfer the protein bands from the gel to nitrocellulose paper. The nitrocellulose was subsequently incubated (in sequence) with BSA, normal rabbit serum, peroxidase-conjugated goat anti-rabbit IgG, and 4-chloro-1-naphthol plus H₂O₂ (the same nitro-cellulose treatment as the immunochemical procedure described above). Both strains were found to produce the same IgG-binding protein bands with mobilities corresponding to molecular weights between approximately 90,000 to approximately 30,000 with a predominant band at 57,000.

Plasmid pGX4533 was subjected to restriction analysis, and a partial restriction map is shown in Figure 2. The single line represents the vector (pGX1066) sequences, while the hatched area represents the DNA that has been inserted into the plasmid vector and which contains the Protein G gene.

The 1.9 kbp HindIII fragment in the insert was subcloned into pGX1066, and the resulting recombinant plasmid (pGX4547) was transformed into E. coli. Western blotting of the proteins produced by this transformant (E. coli GX7841) was done as described above, and the same IgG-binding protein bands were present including the predominant 57,000 band. The transformant was also analyzed in a hemagglutination assay, as described above. Extracts of the transformant agglutinated tanned sheep erythrocytes coated with IgG3 (human myeloma protein) and with unfractionated human IgG, but uncoated erythrocytes were not agglutinated. An extract from a Protein A-producing E. coli strain agglutinated the erythrocytes coated with unfractionated IgG, but not those coated with IgG3 or uncoated erythrocytes. A control E. coli strain which produced neither Protein A nor Protein G failed to agglutinate any of the erythrocyte samples.

These results demonstrate that E. coli strains GX7841, GX7820, and GX7823 produce IgG-binding protein having the properties which are characteristics of Protein G.

EXAMPLE II

DNA and Amino Acid Sequence Data

The DNA sequence of the cloned gene was determined. This sequence is shown in Figure 3. along with the amino acid sequence specified by the DNA sequence. The data in Figure 3 are for the entire 1.9kbp HindIII fragment which contains the cloned Protein G gene, as described above.

It will be appreciated that because of the degeneracy of the genetic code, the nucleotide sequence of the gene can vary substantially. For example, portions or all of the gene could be chemically synthesized to yield DNA having a different nucleotide sequence than that shown in Figure 3, yet the amino acid sequence would be preserved, provided that the proper codon-amino acid assignments were observed. Having established the nucleotide sequence of the Protein G gene and the amino acid sequence of the protein, the gene of the present invention is not limited to a particular nucleotide sequence, but includes all variations thereof as permitted by the genetic code.

The Protein G protein of the present invention is not limited to a protein having the exact amino acid sequence shown in Figure 3. A protein comprising deletions or substitutions in the sequence shown in Figure 3, or additional amino acids at the amino or carboxyl terminus of the protein, are included in the present invention as long as the protein retains the desired IgG-binding properties of Protein G, described above. These variations in amino acid sequence may be achieved by chemical synthesis of the gene, or by known in vitro mutagenesis procedures, for example.

The following abbreviations are used in Figure 3: A = deoxyadenyl T = thymidyl G = deoxyguanyl C = deoxycytosyl

GLY = glycine CYS = cysteine

ALA = alanine MET = methionine

VAL = valine ASP = aspartic acid

LEU = leucine GLU = glutamic acid

ILE = isoleucine LYS = lysine

SER = serine ARG = arginine

THR = threonine HIS = histidine

PHE = phenylalanine PRO = proline

TYR = tyrosine GLN = glutamine

TRP = tryptophan ASN = asparagine

EXAMPLE III

Identification of the Portions of the

Protein G Molecule Responsible for the IgG-binding Activity

By examining the IgG binding activity of protein produced by E. coli strains carrying deleted and modified forms of the cloned protein G gene, the activity was localized to the repeating structure between amino acid residues 228 and 352 (Figure 8). The amino acid sequences of regions B1 and B2 are identical at 49 of the 55 corresponding positions in each. This repeating structure is illustrated in figure 4, where it is indicated as B1 and B2. The 1.9 kbp HindIII fragment indicated in figure 2, which contains the entire coding sequence for protein G, originally isolated from Streptococcus GX7809, was subcloned in bacteriophage M13mp9 [Messing, J., Methods Enzvmol. 101:20 (1983)]. The plasmid pGX4547 was digested with endonuclease HindIII. as was the double stranded replicative form of bacteriophage M13mp9 DNA. The latter was also treated with calf alkaline phosphatase (2 units in 15 ul), which was present during the digestion with HindIII, to prevent recircularization of the vector. After extraction with phenol and precipitation with ethanol, the two digested DNA preparations were mixed and incubated with DNA ligase under ligation conditions. The ligated DNA preparation was used to transfect E. coli strain GX1210 (F' traD36 proA+B+ laclq/ delta-lacZM15 delta-(lac-pro) supE thi zig: :Tn10 hsdR2). Transfected cells from plaques were screened for the production of protein G by colony immunoassay. One which produced a positive assay response was designated mGX4547, and was shown to have the partial restriction map illustrated in figure 5.

Double stranded replicative form DNA isolated from E. coli infected with mGX4547 was digested with endonuclease PstI. After extraction with phenol and ethanol precipitation, the digested DNA was incubated with DNA ligase under ligation conditions in dilute solution (approximately 5 ug digested DNA per ml). The religated DNA preparation was then used to transfect E. coli GX1210. Replicative form DNA was prepared from cells infected from several plaques, and the same infected cells were assayed for .the production of IgG-binding protein by colony immunoassay. Several clones were found by analysis of RF DNA with restriction endonuclease PstI to have lost both the 210 bp and the 415 bp PstI fragments indicated in figures 5 and 6. These clones produced no active IgG-binding protein, as indicated by colony immunoassay. The truncated protein produced by these clones would be expected to contain only a portion of the structure B1, and lack all amino acid sequences distal to B1.

One of the clones obtained from the above transfeetion produced a positive result by colony immunoassay. Restriction analysis of RF DNA from this clone revealed that the phage DNA lacked the 415 bp PstI fragment, but retained the 210 bp fragment. Furthermore, the relative intensity of the 210 bp PstI fragment band on an ethidium bromide-stained agarose gel electrophoretogram suggested that the DNA carried two copies of the 210 bp fragment. DNA sequencing confirmed that the structure of this phage DNA (mGX7880) was as illustrated in figure 6. The protein encoded by the protein G gene carried on this phage DNA would be expected to contain two complete copies of the B structure, an intact B1 sequence followed by a chimera of B1 and B2. It would lack all amino acid sequences distal to B2. This structure results from the fact that the PstI sites which define the 210 bp fragment are located in the B repeating structures at positions corresponding to homologous sequences, and in the same relation to the reading frame of the protein. Polyacrylamide gel electrophoretic analysis revealed that E. coli bearing this DNA produced a protein with IgG-binding activity of approximately the expected size [Fahnestock, et al., J. Bacteriol. 167:870-880 (1986)].

These results indicate that the presence of the B repeated structure is a necessary and sufficient condition for IgG-binding activity of protein G. It was therefore concluded that the B repeating structure was the locus of IgG-binding activity in the molecule. EXAMPLE IV

Expression of the Protein G Gene in Bacillus Subtilis

A synthetic oligonucleotide with a sequence resembling a transcription terminator was first inserted into mGX4547. The sequence of the oligonucleotide was:

5'-pTCGAAAAAAGAGACCGGATATCCGGTCTCTTTTT-3' It is self-complementary, and when double-stranded, produces single stranded ends with the same sequence as those produced by endonuclease SalI. To insert it into mGX4547, the phage DNA was digested with endonuclease SalI, phenol extracted and ethanol precipitated, then incubated with the synthetic oligonucleotide (which had been denatured by heating to 70ºC and slowly cooled to 23ºC) and DNA ligase under ligating conditions. Ligated DNA was used to transfect E. coli GX1210, and clones were screened for the loss of the SalI site and appearance of an EcoRV site, the recognition sequence for which is present on the synthetic oligonucleotide. One clone with the desired structure was designated mGX7872.

Next, sequences distal to the B2 repeated sequence were deleted from mGX7872. This was accomplished by oligonucleotide-directed in vitro mutagenesis. The following oligonucleotide was synthesized:

5'-pCGTTTTGAAGCGACCGGAACCTCTGTAACC-3'. This sequence is complementary on one half to sequences in mGX4547 immediately distal to the B2 sequence, and on the other half to sequences near those coding for the C-terminus of protein G. This oligonucleotide was used as a primer for the in vitro synthesis of double stranded RF DNA, with mGX4547 DNA as template, using standard methods. This DNA was used to transfect E. coli GX1210. Plaques were screened in situ for the ability of phage DNA they produced to hybridize to the radioactive oligonucleotide

5'-(32P)AGCGACCGGAACCTC-3', which is complementary to the desired deleted sequence. One clone with the desired structure was identified and designated mGX7877. Its structure was verified by DNA sequence analysis. The deletion encompasses nucleotides 1651-1896 of the sequence shown in figure 3.

In order to allow fusion of the protein G coding sequence to an expression and secretion vector, a BamHI site was created in the sequence of mGX7877 by oligonucleotide- directed in vitro mutagenesis. A primer oligonucleotide, with the sequence,

5'-pGGTATCTTCGATTGGATCCGGTGAATCAACAGCGAATACCG-3', was used to promote conversion of mGX7877 single stranded DNA to duplex DNA in vitro. This oligonucleotide was complementary to the sequence encoding protein G in mGX7877, but includes an additional 6 nucleotides, GGATCC, which comprise the recognition sequence for endonuclease BamHI. inserted near the beginning of the sequence encoding mature protein G (the product of removal of the secretion signal sequence). The resulting double stranded DNA was used to transfect E. coli GX1210. The RF DNA recovered from cells infected from plaques was screened for the presence of the BamHI site. One with the desired structure was designated mGX8402.

A secretion vector containing the promoter and secretion signal sequence derived from a Bacillus amyloliguefaciens gene encoding subtilisin (apr) has been described by Vasantha and Thompson [J. Bacteriol. 165:837-842 (1984); and U.S. Patent Application, Serial No. 618,902, filed June 8, 1984, and the continuation-in-part thereof. Serial No. 717,800, filed March 29, 1985]. This vector, pGX2134, contains a BamHI site near the end of sequences encoding the secretion signal sequence, to which heterologous genes can be fused in order to promote their expression in B. subtilis, and the secretion of the protein product from the cell. In order to fuse protein G-encoding sequences to this vector, pGX2134 DNA was digested with endonucleases BamHI and PvuII. The RF DNA from mGX8402 was digested with endonucleases BamHI and Smal. After extraction with phenol and precipitation with ethanol, the digested DNA preparations were mixed and incubated with DNA ligase under ligation conditions, and the ligated DNA was used to transform B. subtilis GX8008 (apr deletion, npr deletion, spoOA677) protoplasts by standard methods. Transformants were selected for resistance to chloramphenicol and screened for production of protein G by colony immunoassay. A positive transformant was identified and designated GX8408 (pGX4582). The plasmid pGX4582 was shown to have the structure indicated in figure 7 by restriction analysis. It was presumably formed by insertion into pGX2134, between the BamHI and PvuII sites, of the BamHI fragment of mGX8402 bearing the protein G coding sequences, plus the small BamHI-Smal fragment which is distal to the coding sequences in mGX8402.

Strain GX8408 was shown to produce a protein with the IgG-binding activity of protein G. After growth in appropriate media [Fahnestock and Fisher, J. Bacteriol. 165:796- 804 (1984)], culture supernatants and cell-associated fractions were recovered and subjected to sodium dodecyl sulfate-polyacrylamide gel electrophoretic analysis. After electrophoretic separation, protein bands were transferred to nitrocellulose and stained immunochemically as described in Example I. Material with IgG-binding activity was found in both the culture supernatant and cell-associated fractions. EXAMPLE V

Cloning the Gene Encoding Protein G From Streptococcus GX7805

Chromosomal DNA was isolated from a group G Streptococcus clinical isolate designated GX7805 as described in Example I. A sample of the DNA was digested with restriction endonuclease HindIII and subjected to electrophoresis in a 1% agarose gel under standard conditions. After electrophoresis, DNA fragments were transferred to nitrocellulose as described by Southern J. Mol. Biol. 98:503 (1975). A band of approximately 2.4 kbp containing protein G-encoding sequences was located by hybridization with a radioactive probe consisting of the 1.9 kbp HindIII fragment indicated in Figure 2, originally isolated from Streptococcus strain GX7809. The 1.9 kbp fragment probe was purified by agarose gel electrophoresis and eluted from the gel as described in Example I, then radioactively labeled with 32P by nick translation essentially as described by Rigby, et al. J. Mol. Biol. 113:237 (1977). Hybridization was carried out essentially as described by Wahl et al. [Proc. Natl. Acad. Sci. USA 76:3683-3687 (1979)]. After hybridization and washing to remove unhybridized probe, a radioactive band was located by autoradiography at a position corresponding to a length of 2.4 kbp.

A larger sample of the same GX7805 chromosomal DNA (6 ul) was digested with endonuclease HindIII, and the fragments were separated by electrophoresis in a 1% agarose gel (16 h at 0.35 volts/cm). After staining with ethidium bromide, portions of the gel containing bands of length 2-3 kbp (located relative to a standard consisting of endonuclease HindIII-digested bacteriophage lambda DNA) were excised and crushed to aid in the recovery of the DNA. The DNA was recovered after extraction with phenol as described in Example I.

Plasmid vector pGX1066 DNA (1 ug) was digested with endonuclease HindIII. Following extraction of the reaction mixture with phenol/chloroform/isoamyl alcohol (25:24:1), the DNA was precipitated by adding 0.1 volume 4M LiCl, 10mM EDTA, 20 ug glycogen carrier, and 2.5 vol. 95% ethanol. 0.4 ug of the digested vector DNA was incubated with the recovered HindIII fragments of GX7805 DNA (90% of the material recovered from 6 ug chromosomal DNA) and T4 DNA ligase (International Biotechnologies, Inc., New Haven, CT), under ligation conditions as recommended by the manufacturer, in 20 ul, for 16 h at 15 C.

E. coli SK2267 cells were transformed with 15 ul of the ligated DNA as described in Example I, and the transformed cells were plated on colony immunoassay plates and assayed for the production of immunoglobulin-binding protein as described in Example I. A positive colony was identified. Plasmid DNA isolated from this transformant was found to consist of pGX1066 with a DNA insert of 2.4 kbp. An endonuclease HindIII fragment comprising the insert was subcloned in a bacteriophage M13mp9 vector. The DNA sequence of the 2.4 kbp HindIII fragment was determined, and is presented in Figure 9.

Claims

Claims

1. A cloned Protein G gene.

2. The Protein G gene of Claim 1, which comprises the following deoxyribonucleotide sequence:

fMET GLU LYS GLU LYS

ATG GAM AAM GAM AAM 10

LYS VAL LYS TYR PHE LEU ARG LYS SER ALA PHE GLY LEU ALA AAM GTX AAM TAY TTY YTZ LGN AAM QRS GCX TTY GGX YTZ GCX

20 30

SER VAL SER ALA ALA PHS LEU VAL GLY SER THR VAL PHE ALA QRS GTX QRS GCX GCX TTY YTZ GTX GGX QRS ACX GTX TTY GCX

40 VAL ASP SER PRO ILE GLU ASP THR PRO ILE ILE ARG ASN GLY GTX GAY QRS CCX ATH GAM GAY ACX CCX ATB ATB LGN AAY GGX

50 60

GLY GLU LEU THR ASN LEU LEU GLY ASN SER GLU THR THR LEU GGX GAM YTZ ACX AAY YTZ YTZ GGX AAY QRS GAM ACX ACX YTZ

70 ALA LEU ARG ASN GLU GLU SER ALA THR ALA ASP LEU THR ALA GCX YTZ LGN AAY GAM GAM QRS GCX ACX GCX GAY TTZ ACX GCX

80 ALA ALA VAL ALA ASP THR VAL ALA ALA ALA ALA ALA GLU ASN GCX GCX GTX GCX GAY ACX GTX GCX GCX GCX GCX GCX GAM AAY

90 100

ALA GLY ALA ALA ALA TRP GLU ALA ALA ALA ALA ALA ASP ALA GCX GGX GCX GCX GCX TGG GAM GCX GCX GCX GCX GCX GAY GCX

110

LEU ALA LYS ALA LYS ALA ASP ALA LEU LYS GLU PHE ASN LYS YTZ GCX AAM GCX AAM GCX GAY GCX YTZ AAM GAM TTY AAY AAM

120 130 TYR GLY VAL SER ASP TYR TYR LYS ASN LEU ILE ASN ASN ALA TAY GGX GTX QRS GAY TAY TAY AAM AAY YTZ ATB AAY AAY GCX 140

LYS THR VAL GLU GLY ILE LYS ASP LEU GLN ALA GLN VAL VAL AAM ACX GTX GAM GGX ATH AAM GAY YTZ CAM GCX CAM GTX GTX

150 GLU SER ALA LYS LYS ALA ARG ILE SER GLU ALA THR ASP GLY GAM QRS GCX AAM AAM GCX LGN ATB QRS GAM GCX ACX GAY GGX

160 170

LEU SER ASP PHE LEU LYS SER GLN THR PRO ALA GLU ASP THR

TTZ QRS GAY TTY TTZ AAM QRS CAM ACX CCX GCX GAM GAY ACX

180 VAL LYS SER ILE GLU LEU ALA GLU ALA LYS VAL LEU ALA ASN GTX AAM QRS ATH GAM TTZ GCX GAM GCX AAM GTX TTZ GCX AAY

190 200

ARG GLU LEU ASP LYS TYR GLY VAL SER ASP TYR BIS LYS ASN LGN GAM TTZ GAY AAM TAY GGX GTX QRS GAY TAY CAY AAM AAY

210 LEU ILE ASN ASN ALA LYS TBR VAL GLU GLY VAL LYS GLU LEU TTZ ATB AAY AAY GCX AAM ACX GTX GAM GGX GTX AAM GAM YTZ

220 ILE ASP GLU ILE LEU ALA ALA LEU PRO LYS THR ASP THR TYR ATH GAY GAM ATH TTZ GCX GCX TTZ CCX AAM ACX GAY ACX TAY

230 240

LYS LEU ILE LEU ASN GLY LYS TBR LEU LYS GLY GLU THR THR

AAM TTZ ATH CTX AAY GGX AAM ACX TTZ AAM GGX GAM ACX ACX

250 THR GLU ALA VAL ASP ALA ALA THR ALA GLU LYS VAL PHE LYS ACX GAM GCX GTX GAY GCX GCX ACX GCX GAM AAM GTX TTY AAM

260 270

GLN TYR ALA ASN ASP ASN GLY VAL ASP GLY GLU TRP THR TYR CAM TAY GCX AAY GAY AAY GGX GTX GAY GGX GAM TGG ACX TAY

280 ASP ASP ALA THR LYS THR PHE THR VAL TBR GLU LYS PRO GLU GAY GAY GCX ACX AAM ACX TTY ACX GTX ACX GAM AAM CCX GAM

290 VAL ILE ASP ALA SER GLU LEU THR PRO ALA VAL THR THR TYR GTX ATH GAY GCX QRS GAM TTZ ACX CCX GCX GTX ACX ACX TAY

300 310

LYS LEU VAL ILE ASN GLY LYS THR LEU LYS GLY GLU THR THR

AAM TTZ GTX ATH AAY GGX AAM ACX TTZ AAM GGX GAM ACX ACX 320 THR LYS ALA VAL. ASP ALA GLU THR ALA GLU LYS ALA PHE LYS ACX AAM GCX GTX GAY GCX GAM ACX GCX GAM AAM GCX TTY AAM

330 340

GLN TYR ALA ASN ASP ASN GLY VAL ASP GLY VAL TRP THR TYR CAM TAY GCX AAY GAY AAY GGX GTX GAY GGX GTX TGG ACX TAY

350 ASP ASP ALA TBR LYS THR PHE THR VAL THR GLU MET VAL THR GAY GAY GCX ACX AAM ACX TTY ACX GTX ACX GAM ATG GTX ACX

360 GLU VAL PRO GLY ASP ALA PRO THR GLU PRO GLU LYS PRO GLU GAM GTX CCX GGX GAY GCX CCX ACX GAM CCX GAM AAM CCX GAM

370 380

ALA SER ILE PRO LEU VAL PRO LEU THR PRO ALA THR PRO ILE

GCX QRS ATH CCX TTZ GTX CCX TTZ ACX CCX GCX ACX CCX ATH

390 ALA LYS ASP ASP ALA LYS LYS ASP ASP THR LYS LYS GLU ASP GCX AAM GAY GAY GCX AAM AAM GAY GAY ACX AAM AAM GAM GAY

400 410

ALA LYS LYS PRO GLU ALA LYS LYS ASP ASP ALA LYS LYS ALA GCX AAM AAM CCX GAM GCX AAM AAM GAY GAY GCX AAM AAM GCX

420 GLU THR LEU PRO TBR THR GLY GLU GLY SER ASN PRO PHE PHE GAM ACX TTZ CCX ACX ACX GGX GAM GGX QRS AAY CCX TTY TTY

430 THR ALA ALA ALA LEU ALA VAL MET ALA GLY ALA GLY ALA LEU ACX GCX GCX GCX TTZ GCX GTX ATG GCX GGX GCX GGX GCX TTZ

440

ALA VAL ALA SER LYS ARG LYS GLU ASP

GCX GTX GCX QRS AAM LGN AAM GAM GAY

wherein the 5' to 3' strand, beginning with the amine terminus and the amino acids for which each triplet codes are shown, and wherein within each triplet. X is A, T, C or G Y is T or C

When Y is C, Z is A, T, C or G When Y is T, Z is A or G B is A, T or C Q is T or A

When Q is T, R is C and S is A, T, C or G When Q is A, R is G and S is T or C M is A or G L is A or C

When L is A, N is A or G When L is C, N is A, T, C or G .

3. The Protein G gene of Claim 2 comprising the following deoxyribonucleotide sequence:

AAGCTTTGGTGGAGAAATTGGCTGGCGAATCCAGCTTCACCGGTGTTTCA 50

CCAGTAGATGCTTTCTGTGGTCTTATTGACACGCACTTGTGGCGAGAGTA 100

CTAACAGTCACAGCGACGTTAACTTTATTTTCCTTATGAGAGGTTAAGAA 150

AAAACGTTATTAAATAGCAGAAAAGAATATTATGACTGACGTTAGGAGTT 200

TTCTCCTAACGTTTTTTTTAGTACAAAAAGAGAATTCTCTATTATAAATA 250

AAATAAATAGTACTATAGATAGAAAATCTCATTTTTAAAAAGTCTTGTTT 300

TCTTAAAGAAGAAXATAATTGTTGAAAAATTATAGAAAATCATTTTTATA 350

CTAATGAAATAGACATAAGGCTAAATTGGTGAGGTGATGATAGGAGATTT 400

ATTTGTAAGGATTCCTTAATTTTATTAATTCAACAAAAATTGATAGAAAA 450

ATTAAATGGAATCCTTGATTTAATTTTATTAAGTTGTATAATAAAAAGTG 500

-35 -16 AAATTATTAAATCGTAGTTTCAAATTTGTCGGCTTTTTAATATGTGCTGG 550

MET GLU LYS GLU LYS CATATTAAAATTAAAAAAGGAGAAAAA ATG GAA AAA GAA AAA 592 rbs

10 LYS VAL LYS TYR PHE LEU ARG LYS SER ALA PHE GLY LEU AAG GTA AAA TAC TTT TTA CGT AAA TCA GCT TTT GGG TTA 631

20 30

ALA SER VAL SER ALA ALA PHE LEU VAL GLY SER THR VAL

GCA TCC GTA TCA GCT GCA TTT TTA GTG GGA TCA ACG GTA 670

40

PHE ALA VAL ASP SER PRO ILE GLU ASP THR PRO ILE ILE

TTC GCT GTT GAT TCA CCA ATC GAA GAT ACC CCA ATT ATT 709

50 ARG ASN GLY GLY GLU LEU THR ASN LEU LEU GLY ASN SER CGT AAT GGT GGT GAA TTA ACT AAT CTT CTG GGG AAT TCA 748

60 70

GLU THR THR LEU ALA LEU ARG ASN GLU GLU SER ALA THR

GAG ACA ACA CTG GCT TTG CGT AAT GAA GAG AGT GCT ACA 787

80 ALA ASP LEU THR ALA ALA ALA VAL ALA ASP THR VAL ALA GCT GAT TTG ACA GCA GCA GCG' GTA GCC GAT ACT GTG GCA 826

90 ALA ALA ALA ALA GLU ASN ALA GLY ALA ALA ALA TRP GLU GCA GCG GCA GCT GAA AAT GCT GGG GCA GCA GCT TGG GAA 865

100

ALA ALA ALA ALA ALA ASP ALA LEU ALA LYS ALA LYS ALA

GCA GCG GCA GCA GCA GAT GCT CTA GCA AAA GCC AAA GCA 904

110 120

ASP ALA LEU LYS GLU PHE ASN LYS TYR GLY VAL SER ASP

GAT GCC CTT AAA GAA TTC AAC AAA TAT GGA GTA AGT GAC 943

130 TYR TYR LYS ASN LEU ILE ASN ASN ALA LYS TBR VAL GLUTAT TAC AAG AAT CTA ATC AAC AAT GCC AAA ACT GTT GAA 982

140 GLY ILE LYS ASP LEU GLN ALA GLN VAL VAL GLU SER ALA GGC ATA AAA GAC CTT CAA GCA CAA GTT GTT GAA TCA GCG 1021 150 ³⁹ 160

LYS LYS ALA ARG ILE SER GLU ALA THR ASP GLY LEU SER AAG AAA GCG CGT ATT TCA GAA GCA ACA GAT GGC TTA TCT 1060

170 ASP PHE LEU LYS SER GLN THR PRO ALA GLU ASP THR VAL GAT TTC TTG AAA TCG CAA ACA CCT GCT GAA GAT ACT GTT 1099

180 LYS SER ILE GLU LEU ALA GLU ALA LYS VAL LEU ALA ASN AAA TCA ATT GAA TTA GCT GAA GCT AAA GTC TTA GCT AAC 1138

190 200

ARG GLU LEU ASP LYS TYR GLY VAL SER ASP TYR HIS LYS AGA GAA CTT GAC AAA TAT GGA GTA AGT GAC TAT CAC AAG 1177

210 ASN LEU ILE ASN ASN ALA LYS THR VAL GLU GLY VAL LYS AAC CTA ATC AAC AAT GCC AAA ACT GTT GAA GGT GTA AAA 1216

220 GLU LEU ILE ASP GLU ILE LEU ALA ALA LEU PRO LYS TBR GAA CTG ATA GAT GAA ATT TTA GCT GCA TTA CCT AAG ACT 1255

230 ASP TBR TYR LYS LEU ILE LEU ASN GLY LYS TBR LEU LYS GAC ACT TAC AAA TTA ATC CTT AAT GGT AAA ACA TTG AAA 1294

240 250

GLY GLU THR THR THR GLU ALA VAL ASP ALA ALA THR ALA

GGC GAA ACA ACT ACT GAA GCT GTT GAT GCT GCT ACT GCA 1333

260 GLU LYS VAL PHE LYS GLN TYR ALA ASN ASP ASN GLY VAL GAA AAA GTC TC AAA CAA TAC GCT AAC GAC AAC GGT GTT 1372

270 ASP GLY GLU TRP THR TYR ASP ASP ALA THR LYS THR PHE GAC GGT GAA TGG ACT TAC GAC GAT GCG ACT AAG ACC TTT 1411

280 290

TBR VAL TBR GLU LYS PRO GLU VAL ILE ASP ALA SER GLU ACA GTT ACT GAA AAA CCA GAA GTG ATC GAT GCG TCT GAA 1450

300 LEU THR PRO ALA VAL THR THR TYR LYS LEU VAL ILE ASN TTA ACA CCA GCC GTG ACA -ACT TAC AAA CTT GTT ATT AAT 1489

310 GLY LYS THR LEU LYS GLY GLU THR THR THR LYS ALA VAL GGT AAA ACA TTG AAA GGC GAA ACA ACT ACT AAA GCA GTA 1528 320 330

ASP ALA GLU THR ALA GLU LYS ALA PHE LYS GLN TYR ALA GAC GCA GAA ACT GCA GAA AAA GCC TTC AAA CAA TAC GCT 1567

340 ASN ASP ASN GLY VAL ASP GLY VAL TRP THR TYR ASP ASP

AAC GAC AAC GGT GTT GAT GGT GTT TGG ACT TAT GAT GAT 1606

350 ALA TBR LYS THR PHE THR VAL THR GLU MET VAL THR GLU GCG ACT AAG ACC TTT ACG GTA ACT GAA ATG GTT ACA GAG 1645

360 VAL PRO GLY ASP ALA PRO THR GLU PRO GLU LYS PRO GLU GTT CCT GGT GAT GCA CCA ACT GAA CCA GAA AAA CCA GAA 1684

370 380

ALA SER ILE PRO LEU VAL PRO LEU THR PRO ALA THR PRO

GCA AGT ATC CCT CTT GTT CCG TTA ACT CCT GCA ACT CCA 1723

390 ILE ALA LYS ASP ASP ALA LYS LYS ASP ASP THR LYS LYSATT GCT AAA GAT GAC GCT AAG AAA GAC GAT ACT AAG AAA 1762

400 GLU ASP ALA LYS LYS PRO GLU ALA LYS LYS ASP ASP ALA GAA GAT GCT AAA AAA CCA GAA GCT AAG AAA GAT GAC GCT 1801

410 420

LYS LYS ALA GLU THR LEU PRO THR THR GLY GLU GLY SER AAG AAA GCT GAA ACT CTT CCT ACA ACT GGT GAA GGA AGC 1840

430 ASN PRO PHE PHE THR ALA ALA ALA LEU ALA VAL MET ALA AAC CCA TTC TTC ACA GCA GCT GCG CTT GCA GTA ATG GCT 1879

440 GLY ALA GLY ALA LEU ALA VAL ALA SER LYS ARG LYS GLU GGT GCG GGT GCT TTG GCG GTC GCT TCA AAA CGT AAA GAA 1918

ASP ***

GAC TAATTGTCATTATTTTTGACAAAAAGCTT 1950

4. in combination, a first vector whith comprises a nucleotide sequence specifying Protein G, an origin of replication that is functional in E. coli, and a gene encoding resistance to an antibiotic and a second vector which comprises an origin of replication in E. coli but is lacking said gene encoding antibiotic resistance carried by said first vector, wherein said second vector stabilizes an E. coli host strain transformed with said first and second vectors by competing with said first vector for maintenance in the host and limiting the copy number of said first vector and wherein said transformed host strain can be identified by its ability to survive in the presence of said antibiotic.

5. In combination, the vector of claim 4 wherein said first vector has the identifying characteristics of pGX4530 and the second vector has the identifying characteristics of pGX1066X.

6. An E. coli host strain transformed by the vector of Claim 4 having the identifying characteristics of GX7820.

7. A vector having the capability of replication in a prokaryotic microorganism which comprises a deoxyribonucleotide sequence, or functionally active portions thereof, encoding a protein having the immunoglobulin binding properties of Protein G and which can be stably maintained in said microorganism in the absence of a cryptic helper plasmid.

8. The vector of claim 7, wherein said protein having the immunoglobulin binding properties of Protein G comprises a protein having deletions or substitutions of amino acids or additional amino acids at the amino or carboxyl terminus thereof.

9. The vector of claim 7, wherein said protein having the immunoglobulin binding properties of Protein G comprises the following amino acid sequence: 230 TBR TYR LYS LEU ILE LEU ASN GLY LYS THR LEU LYS ACT TAC AAA TTA ATC CTT AAT GGT AAA ACA TTG AAA 1294

240 250

GLY GLU THR THR THR GLU ALA VAL ASP ALA ALA THR ALA

GGC GAA ACA ACT ACT GAA GCT GTT GAT GCT GCT ACT GCA 1333

260 GLU LYS VAL PHE LYS GLN TYR ALA ASN ASP ASN GLY VAL GAA AAA GTC TTC AAA CAA TAC GCT AAC GAC AAC GGT GTT 1372

270 ASP GLY GLU TRP THR TYR ASP ASP ALA THR LYS THR PHE GAC GGT GAA TGG ACT TAC GAC GAT GCG ACT AAG ACC TTT 1411

280 290

THR VAL THR GLU LYS PRO GLU VAL ILE ASP ALA SER GLU ACA GTT ACT GAA AAA CCA GAA GTG ATC GAT GCG TCT GAA 1450

300 LEU THR PRO ALA VAL THR THR TYR LYS LEU VAL ILE ASN TTA ACA CCA GCC GTG ACA ACT TAC AAA CTT GTT ATT AAT 1489

310

GLY LYS THR LEU LYS GLY GLU THR THR THR LYS ALA VAL

GGT AAA ACA TTG AAA GGC GAA ACA ACT ACT AAA GCA GTA 1528

320 330

ASP ALA GLU THR ALA GLU LYS ALA PHE LYS GLN TYR ALA GAC GCA GAA ACT GCA GAA AAA GCC TTC AAA CAA TAC GCT 1567

340 ASN ASP ASN GLY VAL ASP GLY VAL TRP THR TYR ASP ASP AAC GAC AAC GGT GTT GAT GGT GTT TGG ACT TAT GAT GAT 1606

350 ALA THR LYS THR PHE THR VAL THR GLU GCG ACT AAG ACC TTT ACG GTA ACT GAA .

10. A vector having the capability of replication in a prokaryotic microorganism which comprises the deoxyribonucleotide sequence of Claim 2 or 3 and which can be stably maintained in said microorganism in the absence of a cryptic helper plasmid.

11. The vector of claim 7, 8, 9 or 10 wherein said prokaryotic microorganism is E. coli

11. A vector having the identifying characteristics of PGX4533.

12. A vector having the identifying characteristics of pGX4547.

13. An E. coli strain transformed with the vector of Claim 11 or 12.

14. A method for producing Protein G which comprises cultivating on an aqueous nutrient medium under Protein G-producing conditions, an E. coli host strain transformed by the vectors of claim 4, 5 or 6 said first vector further comprising expression signals which are recognized by said host strain and which direct the expression of said deoxyribonucleotide sequence encoding Protein G; and recovering Protein G so produced.

15. The method of claim 14, wherein said tranformed E. coli host strain has the identifying characteristics of GX7820, deposited with the ATCC as No. 53460.

16. A method for producing a protein with the properties of Protein G which comprises cultivating on an aqueous nutrient medium under protein producing conditions, a microbial host transformed by the vector of Claim 7, 8, 9 or 10, said vector further comprising expression signals which are recognized by said host and which direct the expression of said deoxyribonucleotide sequence, or functionally active portions thereof, encoding a protein having the immunoglobulin binding properties of Protein G, and recovering Protein so produced.

17. The method of claim 16 wherein said protein so produced comprises a protein having deletions or substitutions of amino acids or additional amino acids at the amino or carboxyl terminus thereof.

18. The method of Claim 16 wherein the protein so produced has the following amino acid sequence:

230 TBR TYR LYS LEU ILE LEU ASN GLY LYS TBR LEU LYS ACT TAC AAA TTA ATC CTT AAT GGT AAA ACA TTG AAA 1294

240 250

GLY GLU TBR THR THR GLU ALA VAL ASP ALA ALA THR ALA

GGC GAA ACA ACT ACT GAA GCT GTT GAT GCT GCT ACT GCA 1333

260 GLU LYS VAL PHE LYS GLN TYR ALA ASN ASP ASN GLY VAL GAA AAA GTC TTC AAA CAA TAC GCT AAC GAC AAC GGT GTT 1372

270 ASP GLY GLU TRP THR TYR ASP ASP ALA THR LYS TBR PBE GAC GGT GAA TGG ACT TAC GAC GAT GCG ACT AAG ACC TTT 1411 280 290

THR VAL THR GLU LYS PRO GLU VAL ILE ASP ALA SER GLU ACA GTT ACT GAA AAA CCA GAA GTG ATC GAT GCG TCT GAA 1450

300 LEU THR PRO ALA VAL THR THR TYR LYS LEU VAL ILE ASNTTA ACA CCA GCC GTG ACA ACT TAC AAA CTT GTT ATT AAT 1489

310 GLY LYS THR.LEU LYS GLY GLU THR THR THR LYS ALA VAL GGT AAA ACA TTG AAA GGC GAA ACA ACT ACT AAA GCA GTA 1528

320 330

ASP ALA GLU THR ALA GLU LYS ALA PHE LYS GLN TYR ALA GAC GCA GAA ACT GCA GAA AAA GCC TTC AAA CAA TAC GCT 1567

340 ASN ASP ASN GLY VAL ASP GLY VAL TRP THR TYR ASP ASP AAC GAC AAC GGT GTT GAT GGT GTT TGG ACT TAT GAT GAT 1606

350 ALA THR LYS THR PHE THR VAL THR GLU GCG ACT AAG ACC TTT ACG GTA ACT GAA

1567

19. The method of Claim 16 wherein the protein so produced has an amino acid sequence comprising:

230 THR TYR LYS LEU ILE LEU ASN GLY LYS THR LEU LYS ACT TAC AAA TTA ATC CTT AAT GGT AAA ACA TTG AAA 1294

240 250

GLY GLU THR THR THR GLU ALA VAL ASP ALA ALA THR ALA

GGC GAA ACA ACT ACT GAA GCT GTT GAT GCT GCT ACT GCA 1333

260 GLU LYS VAL PHE LYS GLN TYR ALA ASN ASP ASN GLY VAL GAA AAA GTC TTC AAA CAA TAC GCT AAC GAC AAC GGT GTT 1372

270 ASP GLY GLU TRP TBR TYR ASP ASP ALA THR LYS THR PHE GAC GGT GAA TGG ACT TAC GAC GAT GCG ACT AAG ACC TTT 1411

280 THR VAL THR GLU ACA GTT ACT GAA

20. The method of claim 16 wherein the protein so produced has an amino acid sequence comprising:

300 THR THR TYR LYS LEU VAL ILE ASN ACA ACT TAC AAA CTT GTT ATT AAT 1489

310 GLY LYS THR LEU LYS GLY GLU THR THR THR LYS ALA VAL GGT AAA ACA TTG AAA GGC GAA ACA ACT ACT AAA GCA GTA 1528

320 330

ASP ALA GLU THR ALA GLU LYS ALA PHE LYS GLN TYR ALA GAC GCA GAA ACT GCA GAA AAA GCC TTC AAA CAA TAC GCT 1567

340 ASN ASP ASN GLY VAL ASP GLY VAL TRP THR TYR ASP ASP

AAC GAC AAC GGT GTT GAT GGT GTT TGG ACT TAT GAT GAT 1606

350 ALA TBR LYS THR PHE THR VAL THRR GLU GCG ACT AAG ACC TTT ACG GTA ACT GAA

21. The method of claim 16 wherein said vector promotes the integration of said deoxyribonucleotide sequence encoding Protein G into the chromosome of said microbial host.

22. The method of claim 16 wherein said microbial host is E. coli

23. The method of claim 16 wherein said host is Bacillus subtilis.

24. The method of Claim 22, wherein said transformed E. coli host strain has the identifying characteristics of GX7823, deposited with the ATCC as No. 53461.

25. The method of Claim 22, wherein said transformed E. coli host strain has the identifying characteristics of GX7841.

26. The method of claim 23, wherein said transformed Bacillus subtilis strain has the identifying characteristics of GX8408.

27. Protein G produced by the method of claim 14.

28. Protein G produced by the method of claim 15.

29. The protein produced by the method of claim 16.

30. The protein produced by the method of claim 18.

31. The protein produced by the method of claim 19.

32. the protein produced by the method of claim 20.

33. A recombinant vector comprising the DNA sequence o Figure 9, or a Protein G-like coding fraction thereof.

34. A Protein G-like material comprising the amino acid sequence Figure 9, or the fraction thereof which has the IgG-binding properties of Protein G.

35. A recombinant DNA vector of the formula:

-(-B-b-)_n-

wherein B is B1, B2 or B3, n is 1-20,

Bl is the DNA sequence

230 TBR TYR LYS LEO ILE LEU ASN GLY LYS THR LEO LYS ACT TAC AAA TTA ATC CTT AAT GGT AAA ACA TTG AAA 1294

B1

240 250 GLY GLU TBR TBR TBR GLU ALA VAL ASP ALA ALA TBR ALA

GGC GAA ACA ACT ACT GAA GCT GTT GAT GCT GCT ACT GCA 1333

Bl

260

GLU LYS VAL PBE LYS GLN TYR ALA ASN ASP ASN GLY VAL GAA AAA GTC TTC AAA CAA TAC GCT AAC GAC AAC GGT GTT 1372

B1

270

ASP GLY GLU TRP TBR TYR ASP ASP ALA TBR LYS TBR PBE

GAC GGT GAA TGG ACT TAC GAC GAT GCG ACT AAG ACC TTT 1411

^"Bl

TBR VAL TBR GLU ACA CTT ACT CAA

B1 B2 is the DNA sequence

300 TBR TBR TYR LYS LEU VAL XLS ASN ACA ACT TAC AAA CTT GTT ATT AAT 1489 B2

310 GLY LYS TBR LEU LYS GLY GLU TBR THR TBR LYS ALA VAL

GGT AAA ACA TTG AAA GGC GAA ACA ACT ACT AAA GCA GTA 1528 B2

320 330

ASP ALA GLU TBR ALA GLU LYS ALA PBS LYS GLN TYR ALA GAC GCA GAA ACT GCA GAA AAA GCC TTC AAA CAA TAC GCT 1567 B2

340 ASN ASP ASN GLY VAL ASP GLY VAL TRP TBR TYR ASP ASP AAC GAC AAC GGT GTT GAT GGT GTT TGG ACT TAT GAT GAT 1606 B2

350 ALA THR LYS TBR PBE TBR VAL TBR GLU GCG ACT AAG ACC TTT ACG GTA ACT GAA

B2 B3 is a hybrid DNA sequence of Bl and B2, and b is the DNA sequence

290 LYS PRO GLU VAL ILE ASP ALA SBR GLU AAA CCA GAA GTG ATC GAT GCG TCT GAA 1450

LEU TBR PRO AIA VAL TTA ACA CCA GCC GTG

36. The recombinant DNA vector of claim 35, wherein said hybrid DNA sequence B3 comprises

37. A Protein G-like material of the formula:

-(-B-b-)_n-

wherein B is B1, B2 or B3, n is 1-20

B1 is the amino acid sequence 230

TBR TYR LYS LEU XLS LEU ASN GLY LYS TBR LEU LYS

ACT TAC AAA TTA ATC CTT AAT GGT AAA ACA TTG AAA 1294

240 250

GLY GLU TBR TBR TBR GLU ALA VAL ASP ALA ALA TBR ALA

GGC GAA ACA ACT ACT GAA GCT GTT GAT GCT GCT ACT GCA 1333

B1

260

GLU LYS VAL PBE LYS GLN TYR ALA ASN ASP ASN GLY VAL CAA AAA GTC TTC AAA CAA TAC GCT AAC GAC AAC GGT GTT 1372

B1

270

ASP GLY GLU TRP TBR TYR ASP ASP ALA TBR LYS TBR PBE

GAC GGT GAA TGG ACT TAC GAC GAT GCG ACT AAG ACC TTT 1411 Bl 280

TBR VAL TBR GLU ACA GTT ACT GAA

B1

B2 is the amino acid sequence

300 TBR TBR TYR LYS LEU VAL XLS ASN ACA ACT TAC AAA CTT GTT ATT AAT 1489

B2

310

GLY LYS TBR LEU LYS GLY GLU TBR TBR TBR LYS ALA VAL

GGT AAA ACA TTG AAA GGC GAA ACA ACT ACT AAA GCA GTA 1528

B2

320 330

ASP ALA GLU TBR ALA GLU LYS ALA PBS LYS GLN TYR ALA

GAC GCA GAA ACT GCA GAA AAA -GΕC2C TTC AAA CAA TAC GCT 1567

340

ASN ASP ASN GLY VAL ASP GLY VAL TRP TBR TYR ASP ASP AAC GAC AAC GGT GTT GAT GGT GTT TGG ACT TAT GAT GAT 1606 B2

350

ALA TBR LYS TBR PBS TBR VAL TBR GLU GCG ACT AAG ACC TTT ACG GTA ACT GAA B2 B3 is a hybrid DNA sequence of Bl and B2, and b is the amino acid sequence

290 LYS PRO GLU VAL XLS ASP ALA SER GLU

AAA CCA GAA GTG ATC GA.T GCG T.CT GAA 1450

LEU TBR PRO AIA VAL TTA ACA CCA GCC GTG C

38. The Protein G-like material of claim 37, wherein said hybrid amino acid sequence comprises __ % M C Λ U

at r ^ ι ιr T

39. The Protein G-like material of claim 37 wherein said protein has deletions or substitutions of amino acids or additional amino acids at the amino or carboxyl terminus thereof wherein said protein has the immunoglobulin properties of Protein G.