FIGURE 4.

Effect of AgrD C-terminal truncations on AIP production and AgrB endopeptidase activity. A, graphic of AgrD C-terminal truncations. B, AIP production for each truncation (gray bars) expressed in SH1001 (Δagr::Tet). Cell-free supernatants were prepared and tested in the agr inhibition bioassay. For controls, full-length AgrD is shown as a black bar, and the reporter control is shown as a white bar. As an additional control, a construct without AgrD was also included. C, AgrB cleavage of His₆-AgrD truncations. Each AgrD construct was co-expressed in E. coli with AgrB and immunoblotted with anti-His monoclonal antibody. For comparative purposes, the immunoblot lanes were aligned with AIP bioassay results in B.