FIG. 4.

Spa33-His susceptibility to extracellular protease. Each strain was grown with arabinose. Equivalent culture aliquots were incubated in the presence or absence of proteinase K (PK, 100 μg ml⁻¹) and/or Congo red (CR, 20 μM), as indicated. Total protein corresponding to 10⁸ bacteria per sample was then analyzed by immunoblotting with either anti-His or anti-β-lactamase antibodies (indicated next to arrows). Strains: (A) BS625 (spa33-1/P_BAD-spa33⁺-his); (B) BS625 (spa33-1/P_BAD-spa33⁺-his); (C) BS626 (virulence plasmid-cured strain bearing a P_BAD-spa33⁺-his fusion in trans); (D) BS634 (2457T/P_BAD-spa33⁺-his); and (E) BS627 (ΔipaB/P_BAD-spa33⁺-his).