FIG. 6.

Overlay assay for chaperone-adhesin binding to the PapC C-terminal truncation mutants. OM was isolated from bacteria expressing either full-length PapC [809(wt)], the indicated PapC truncation mutant, or vector only (pMON6235Δcat). The OM was incubated in sample buffer at 95°C, separated by SDS-PAGE, and transferred to polyvinylidene difluoride membrane. The membrane was incubated with purified PapDG chaperone-adhesin complexes (A), or PapD only as a negative control (B). PapD alone does not bind to the usher. Binding of PapDG or PapD was determined by immunoblotting with anti-PapD antibody and visualized by alkaline phosphatase development. The bands present in panel B and the vector-alone lane in panel A represent background binding to OM proteins.