FIG. 2.

Expression and folding of PapC mutant proteins in the OM. The OM was isolated from strain SF100 expressing WT PapC, PapCΔ2-11 (A), or the indicated alanine substitution PapC mutant protein (B). Duplicate samples were incubated for 10 min in SDS sample buffer at room temperature (RT; 25°C) or 95°C prior to separation by SDS-PAGE. The ushers were detected by blotting with anti-His tag antibody. The presence of the faster-migrating folded monomer form (∼60 kDa) and the slower-migrating oligomeric form (∼200 kDa) in the RT-treated samples indicates proper folding of the usher in the OM. Each of the ushers exhibits heat-modifiable mobility.