FIG 5 .

pESI conjugation and pilus transcription are regulated by TraB and FNR. (A) Gene organization of the pil operon carried on pESI. Arrowheads show the location and orientation of the different open reading frames (ORFs). Putative regulatory genes are shown in red. (B and C) RNA was extracted from cultures of S. Infantis 119944 (wild type [wt]) and its derivative mutants (traA, traB, and fnr) and traB/pWSK29::traB and fnr/pWSK29::fnr complemented strains grown in LB under microaerobic conditions at 37°C. qRT-PCR analyses was conducted to determine the fold change in the transcription of pilV (B) and pilS and pilT (C) in the indicated backgrounds relative to the wild-type strain. (D) pESI conjugation between S. Infantis strain 119944 or its fnr-, traA-, and traB-derived mutant strains and E. coli ORN172 were conducted on LB plates under microaerobic conditions. Results show the mean and SD from at least three biological repeats. One-way ANOVA with Dunnett’s multiple comparison test was implemented to determine statistical significance. *, P < 0.005; **, P < 0.001; ***, P < 0.0001; ns, not significant.