Fibronectin Binding Protein A (FnBPA)

Fibronectin binding protein A (FnBPA) is a Staphylococcus aureus MSCRAMM cell surface-bound protein that binds to both fibronectin and fibrinogen. It is an adhesin which enables Staphylococcus aureus (S. aureus) to adhere to host cells of another organism, and an invasin facilitating its internalisation into these cells. This is true over a range of different cell types. The FnBP alone is capable of providing this invasive property, without the requirement of co-receptors. Even FnBP coated beads have been shown to become internalised into cells. S. aureus is able to bind to host cells in the absence of the FnBP, but its adherence and invasive properties are much reduced. The FnBP inserts into the cell wall of S. aureus by means of a C-terminal LPXTG anchor. Two fibronectin binding domains have been identified - one is present in the C-terminal D repeat region, and one in the N-terminal A region.