Fig. 6.

In vivo and in vitro effects of synthesized TDRNTT and DRNTT peptides on PsrfA-luc expression and srfA promoter fragment binding to ComA in the presence or absence of RapH. (A) PsrfA promoter activity in competence medium is shown after 1.9 h of growth when only rapH is overexpressed. The effects of several TDRNTT (▵) or DRNTT (□) concentrations are presented as a percentage of the wild-type activity at the same time. The wild-type reference is the level of the PsrfA-luc promoter activity when rapH and phrH are both overexpressed. The full expression curves are shown in Fig. S6 in the supplemental material. (B) EMSA performed as described in Materials and Methods using 0.1 nM radiolabeled srfA promoter fragment. A dose-response experiment of TDRNTT on the ComA DNA-binding in the presence of RapH is presented in Fig. S7 in the supplemental material.