Fig. 8.

Expression of T3SS1 genes in the absence of ExsD is dependent on ExsA.

A. RT-PCR showing that T3SS1 genes are not transcribed in the ΔexsA exsD strain while transcription of T3SS1 genes is restored in ΔexsA exsD : pexsA strain growing in LB-S. Mock reactions (−), which did not contain reverse transcriptase in the RT reaction, were used as controls against genomic contamination of the RNA preparations. SecY was a house-keeping gene used as an internal control to ensure that RNA was present in all samples.

B. Western blot showing expression and secretion of Vp1656 for the double mutant strain ΔexsA exsD and ΔexsA exsD strain complemented with a wild-type exsA gene in trans when grown in LB-S for 4 h. Vp1656 was detected with polyclonal anti-Vp1656 antibody and ‘N’ in the upper panel represents a non-specific band that serves as a positive detection control.