title: Extensive sequence homology between IgA receptor and M proteins in Streptococcus pyogenes.
abstract: Many strains of Streptococcus pyogenes are known to express a receptor for IgA. The complete nucleotide sequence of the gene for such a receptor, protein Arp4, has been determined. The deduced amino acid sequence of 386 residues includes a signal sequence of 41 amino acids and a putative membrane anchor region, both of which are homologous to similar regions in other streptococcal surface proteins. The processed form of the IgA receptor has a length of 345 amino acids and a calculated molecular weight of 39544. The N-terminal sequence of the processed form is different from that previously found for a similar IgA receptor isolated from a S. pyogenes strain of type M60. The sequence of protein Arp4 shows extensive homology to the C-terminal half of streptococcal M proteins, but not to the streptococcal IgG receptor protein G or staphlyococcal protein A. Apart from the membrane anchor, this homology includes a sequence of 119 amino acid residues containing three repeated units and a 54-residue sequence without repeats. The protein expressed in Escherichia coli is found in the periplasmic space, in which it constitutes the major protein. Protein Arp4 is the first example of a surface protein that has both immunoglobulin-binding capacity and structural features characteristic of M proteins.
authors.affiliation: Department of Microbiology, University of Lund, Sweden.
authors.forename: E
authors.initials: E
authors.lastname: Frithz
authors.forename: L O
authors.initials: LO
authors.lastname: Hedén
authors.forename: G
authors.initials: G
authors.lastname: Lindahl
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D015139:Blotting, Southern; D015153:Blotting, Western; D002352:Carrier Proteins; D004269:DNA, Bacterial / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D007070:Immunoglobulin A / Q000378:metabolism; D008969:Molecular Sequence Data; D011961:Receptors, Fc; D011971:Receptors, Immunologic / Q000235:genetics* / Q000378:metabolism; D012091:Repetitive Sequences, Nucleic Acid; D015183:Restriction Mapping; D012689:Sequence Homology, Nucleic Acid; D013297:Streptococcus pyogenes / Q000235:genetics*
chemical_list: D000596:Amino Acids; D000942:Antigens, Bacterial; C062462:Arp4 protein, Streptococcus pyogenes; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D002352:Carrier Proteins; D004269:DNA, Bacterial; C045281:IgA receptor; D007070:Immunoglobulin A; D011961:Receptors, Fc; D011971:Receptors, Immunologic; C014689:streptococcal M protein