Msb2 and its proteolytic processing are involved in biofilm formation.

<p>Biofilm mass was compared in the absence (white bars) or presence (black bars) of 10 μM PA in CAI4, <i>msb2Δ/Δ</i>, <i>msb2Δ/Δ</i>+, and various <i>SAP</i> deletion cells (A), and the absolute value of reduction in biofilm formation in the presence of PA was calculated (B). Statistical analysis of differences in biomass for each strain with or without PA at P≤0.05(*), P≤0.01(**) and P≤0.001(***) are shown. CAI4 cells had significantly reduced (P<0.001) biofilm formation in the presence 10 μM PA; however <i>msb2</i>Δ/Δ cells produced lower biomass that was not further reduced by PA. Restoration of Msb2 (<i>msb2</i>Δ/Δ+) reversed the biofilm formation defect and restored PA sensitivity. Among mutants with equivalent levels of biofilm formation to WT cells, <i>sapΔ/Δ1/2/3</i> but not <i>sapΔ/Δ4/5/6</i> had further reduction of biomass in the presence of PA. Among <i>sap</i> mutants with biofilm formation defects without PA, <i>sap8Δ/Δ</i> cells had largest deficit in biomass production that was reduced by PA; while <i>sap9Δsap10Δ</i> cells had slightly reduced biofilm formation that was substantially reduced further by PA (B).