Fibronectin binding protein B binds to loricrin and promotes corneocyte adhesion by Staphylococcus aureus

Colonisation of humans by Staphylococcus aureus is a major risk factor for infection, yet the bacterial and host factors involved are not fully understood. The first step during skin colonisation is adhesion of the bacteria to corneocytes in the stratum corneum where the cornified envelope protein loricrin is the main ligand for S. aureus. Here we report a novel loricrin-binding protein of S. aureus, the cell wall-anchored fibronectin binding protein B (FnBPB). Single-molecule force spectroscopy revealed both weak and ultra-strong (2 nN) binding of FnBPB to loricrin and that mechanical stress enhanced the strength of these bonds. Treatment with a peptide derived from fibrinogen decreased the frequency of strong interactions, suggesting that both ligands bind to overlapping sites within FnBPB. Finally, we show that FnBPB promotes adhesion to human corneocytes by binding strongly to loricrin, highlighting the relevance of this interaction to skin colonisation. The first step during skin colonization by is its adhesion to corneocytes. Da Costa et al. show that the cell wall-anchored fibronectin binding protein B (FnBPB) of S. aureus binds to loricrin. Applying single cell force spectroscopy, they demonstrate that this interaction promotes adhesion of S. aureus to human corneocytes.

Automated summary

This study identifies a novel loricrin-binding protein, FnBPB, in Staphylococcus aureus and demonstrates through single-molecule force spectroscopy that FnBPB strengthens the adhesion of S. aureus to human corneocytes through its strong binding to loricrin.