Identification and characterization of a novel fibronectin-binding protein on the surface of group A streptococci.
Understanding the role surface proteins play in the interaction of group A streptococci with epithelial cells is an important step toward the development of new strategies to fight infections. Fibronectin-binding proteins in streptococci and staphylococci have been described as important mediators for adherence to eukaryotic cells. In the present study we describe a new Streptococcus pyogenes fibronectin-binding protein (PFBP). The gene encoding the PFBP protein (pfbp) was identified from an M12 strain genomic library. It encodes a protein of 127.4 kDa which contains the LPXTGX motif characteristic of cell wall-associated proteins in gram-positive organisms and is among the largest surface molecules described for group A streptococci. The pfbp gene is transcribed during cell growth and was present in several class I and II streptococcal strains tested. The deduced amino acid sequence of PFBP exhibits a variable N-terminal region and a conserved C-terminal region when compared to most fibronectin-binding proteins identified from other gram-positive bacteria. The N-terminal region presents a stretch of 105 amino acids with no homology with N-terminal regions of previously described fibronectin-binding molecules, while the C-terminal region contains three repeat domains that share significant similarity with the repeat regions of fibronectin-binding proteins from S. pyogenes, S. dysgalactiae, and S. equisimilis. The PFBP repeated region, when expressed on the surface of S. gordonii, a commensal organism, binds to soluble and immobilized fibronectin. This study also shows that, in addition to pfbp, a second gene homologous with that of protein F1 (which also codes for a fibronectin-binding protein) is transcribed during cell growth in the same S. pyogenes strain.
Rocha
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Laboratory of Bacterial Pathogenesis and Immunology, The Rockefeller University, New York, New York 10021, USA. rochac@rockvax.rockefeller.edu
Fischetti
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VA
D018829:Adhesins, Bacterial / Q000235:genetics; D000595:Amino Acid Sequence; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics* / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics* / Q000378:metabolism; D004269:DNA, Bacterial; D005353:Fibronectins / Q000378:metabolism*; D015870:Gene Expression; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid; D013297:Streptococcus pyogenes / Q000235:genetics* / Q000254:growth & development; D014158:Transcription, Genetic
D018829:Adhesins, Bacterial; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D002352:Carrier Proteins; D004269:DNA, Bacterial; D005353:Fibronectins; C078635:fibronectin-binding proteins, bacterial