Schematic representation of fibronectin binding protein A (FnBPA) and B
(FnBPB) of S. aureus 8325-4. The N-termini of FnBPA and FnBPB
contain a signal sequence (S) followed by the A domain that comprises subdomains
N1, N2, and N3 that are involved in cell-cell aggregation, and binding to
fibrinogen (Fg) and elastin. The A-domain of FnBPB has also been shown to bind
fibronectin (Fn). Following the A domains are tandemly repeated
fibronectin-binding motifs (numbered). At the C-termini are proline-rich repeats
(PRR), wall (W)- and membrane (M)-spanning domains, and the sortase recognition
motif LPETG. Identity percentage for the A region between the two proteins is
45%, whereas the repeat region is 94% (Jonsson,
et al., 1991).