Fig. 1: FnBPB and ClfB mediate the adherence of S. aureus to loricrin.

a Schematic diagram showing the domain organisation of FnBPB and ClfB. The signal sequence (S) is followed by domains N1, N2, and N3. A series of fibronectin-binding repeats (FnBPB) or serine-aspartate repeats (ClfB) form a stalk that projects the N2 and N3 domains from the surface of the bacterium. The wall spanning region (W) is linked to the sorting signal (SS) which is processed by sortase A so that the C-terminus of the protein is anchored to peptidoglycan in the cell wall. b AD08 or mutants deficient in ClfB and/or FnBPA and/or FnBPB and, c S. aureus SH1000 deficient in ClfA, ClfB, FnBPA, and FnBPB [SH1000 4X] carrying pALC2073::fnbB (pFnBPB) or empty pALC2073 were grown to exponential phase (OD₆₀₀ = 0.35), adjusted to an OD₆₀₀ of 1.0 and incubated in microtiter plates coated with GST-tagged full length loricrin (GST-Loricrin) for 2 h. Following incubation, the wells were washed, adherent cells were stained with crystal violet, and the absorbance was read at 570 nm. The datum points on the graph represent the mean values of three independent biological experiments and error bars show the standard deviation. The ligand concentration given on the x-axis is the concentration of the solution used to coat the wells. b Statistical analysis was performed using a two-way ANOVA with a Dunnett´s multiple comparison test to compare variances between AD08 and the mutants at the 31.25 nM GST-loricrin concentration. ***P = 0.0001. c Statistical analysis was performed using a two-way ANOVA with Sidak´s multiple comparison test to compare variances between the strain carrying the plasmid expressing FnBPB and the empty plasmid at the 62.50 nM GST-loricrin concentration. ***P = 0.0000007. No symbol indicates P > 0.05.