Binding of a peptide from a Streptococcus dysgalactiae MSCRAMM to the N-terminal F1 module pair of human fibronectin involves both modules

Host invasion by a number of pathogenic bacteria such as staphylococci and streptococci involves binding to fibronectin, a ubiquitous extracellular matrix protein. On the bacterial side, host extracellular matrix adherence is mediated by MSCRAMMs (microbial surface components recognizing adhesive matrix molecules) which, in some cases, have been identified to be important virulence factors. In this study we used nuclear magnetic resonance spectroscopy to characterize the interaction of B3, a synthetic peptide derived from an adhesin of Streptococcus dysgalactiae, with the N-terminal module pair ¹F1²F1 of human fibronectin. ¹F1²F1 chemical shift changes occurring on formation of the ¹F1²F1/B3 complex indicate that both modules bind to the peptide and that a similar region of each module is involved. A similar surface of the ⁴F1⁵F1 module pair had previously been identified as the binding site for a fibronectin-binding peptide from Staphylococcus aureus.