A novel, anchorless streptococcal surface protein that binds to human immunoglobulins.
We have characterized a novel surface protein from urea extract of whole cells of group A Streptococcus pyogenes (GAS). A major protein band (35kD) was found to hybridize with human IgG by Western blotting. A search of the N-terminal amino acid sequence of this protein by using the GAS genome sequence database revealed an open reading frame that encoded a 38-kDa protein with a signal peptide sequence. We have named this protein streptococcal immunoglobulin-binding protein 35 (Sib35). It was found to be an anchorless protein with no LPXTG motif, distinct from the M protein superfamily exhibiting immunoglobulin-binding activity, and partially secreted in the culture supernatant. Recombinant Sib35 was also shown to bind human IgA and IgM. The sib35 gene was found in all GAS strains examined, but not in oral, group B, C, or G streptococcal strains. These results suggest that Sib35 is a unique immunoglobulin-binding protein in GAS.
Department of Oral and Molecular Microbiology, Graduate School of Dentistry, Osaka University, 1-8 Yamadaoka, Suita, 565-0871, Osaka, Japan. kawabata@dent.osaka-u.ac.jp
Shigetada
S
Kawabata
Yasuharu
Y
Tamura
Jumpei
J
Murakami
Yutaka
Y
Terao
Ichiro
I
Nakagawa
Shigeyuki
S
Hamada
D000595:Amino Acid Sequence; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D016384:Consensus Sequence; D005798:Genes, Bacterial; D006801:Humans; D007074:Immunoglobulin G / Q000378:metabolism; D007136:Immunoglobulins / Q000378:metabolism*; D008969:Molecular Sequence Data; D013297:Streptococcus pyogenes
D001425:Bacterial Outer Membrane Proteins; D002352:Carrier Proteins; D007074:Immunoglobulin G; D007136:Immunoglobulins