Fc-receptor and M-protein genes of group A streptococci are products of gene duplication.

Abstract

The partial nucleotide sequence for an Fcreceptor gene from an M-type 76 group A streptococcus was determined. DNA sequence analysis revealed considerable sequence similarity between the Fc-receptor and M-protein genes in their proposed promoter regions, signal sequences, and 3' termini. Additional analysis indicated that the deduced Fc-receptor protein contains a proline-rich region and membrane anchor region highly similar to that of M protein. (7). We previously reported the cloning and expression of an Fc-receptor gene from group A streptococci (8, 9). Our initial results, based on Southern hybridization data, indicated that DNA sequence similarity existed between the Fc-receptor genetic locus (fcrA76) and the M12 gene (emm12) (8). Here we report a partial nucleotide sequence offcrA76 and compare it to several M-protein genes.* Our analysis indicated that the cloned receptor protein (FcRA76) is highly similar to M protein in its secondary structure and in organization of functional domains. Extensive amino acid sequence similarity between FcRA76 and M proteins in their signal peptides was observed. The deduced amino acid sequence also indicated that FcRA76 contains a proline-rich region and a portion of a C-terminal membrane anchor sequence, both similar to that of M6 and M24 proteins (10). From these results, we postulated that streptococci retain a superfamily of genes that encode surface proteins with heterologous functions: a family of immunoglobulin receptors and a family of antiphagocytic M proteins. We proposed that homologous recombination between FcRA76 and M-protein genes is a potential means for streptococci to generate antigenic diversity in their surface proteins. § MATERIALS AND METHODSBacterial Strains, Plasmids, Bacteriophage, and Media. Escherichia coli strains JM83, JM105, and JM109, the plasmid expression vectors pUC9 and pUC19, and phage M13mpl8 and M13mp19 were gifts of J. Messing and have been described (11). E. coli JM83, JM109, and DH5a were grown in LB broth or, after transformation with chimeric pUC plasmids, in LB broth/agar containing ampicillin at 50 jig/ml. E. coli JM105 was grown in M9 medium as described (12). The recombinant plasmid pDH56 and the group A streptococcal strain CS110 have been described (8).Preparation of Streptococcal DNA and Isolation of Plasmid DNA. Preparation of DNA from group A streptococci and of plasmid DNA from E. coli have been described (8).Recombinant DNA Techniques. Restriction endonucleases were purchased from Bethesda Research Laboratories and New England Biolabs, and digestions were performed as recommended by the suppliers. Gel electrophoresis was performed in either 0.7% or 1% agarose gels. The method for transfer of DNA to nitrocellulose has been described (13). Southern (14) and colony (15) blot hybridizations were done using heparin as a blocking agent (16), and standard conditions were used for DNA ligation and radiolabeling and for transformation of E. coli (13).DNA Sequencing and Analysis. Previous results indicated that fcrA76 ...

Identification of a divergent M protein gene and an M protein-related gene family in Streptococcus pyogenes serotype 49

“…In support of this model, the sequences upstream offcrA are similar to those upstream of emml2 (21), and the sequences downstream of ennX are similar to the sequences downstream of emm24. Furthermore, scpA is linked to emml2 (7) and is also just downstream of ennX.…”

“…Heath and Cleary (20) report that a type II IgG Fc receptor gene (fcrA) is present in a type 76 (OF-positive) streptococcal strain. These authors show thatfcrA contains sequences similar to M protein genes and is located in the same chromosomal position as emml2, as judged by upstream sequence similarities (21). Heath also reports (Ph.D thesis, University of Minnesota, Minneapolis, 1988) that the M76 gene is situated just downstream offcrA.…”

Conserved and variable regions in protein Arp, the IgA receptor of Streptococcus pyogenes

“…Sequencing of the genes for several Ig-binding cell surface proteins of S. pyogenes has shown that these molecules are also members of the M protein family (Frithz et al, 1989;Heath & Cleary, 1989;Gomi et al, 1990;Bessen & Fischetti, 1992;O'Toole et al, 1992). Some of these Ig-binding proteins have C repeats, like the classical M proteins, while others have a different type of repeat, the A repeat, in the central part of the sequence.…”

Protein GRAB of Streptococcus pyogenes Regulates Proteolysis at the Bacterial Surface by Binding α2-Macroglobulin

“…M proteins bind several human plasma proteins like fibrinogen (3), IgG (4,5), and regulatory proteins of the complement system (6,7). The binding activities of M proteins have been proposed to be of importance for the antiphagocytic activity of these proteins (2, 6 -9).…”