Reciprocal regulation of pH 6 antigen gene loci by PhoP and RovA in Yersinia pestis biovar Microtus.

To explore the transcriptional regulation of the psaEF and psaABC loci by the RovA and PhoP regulators in Yersinia pestis. Primer extension, LacZ fusion, gel mobility shift and DNase I footprinting assays were conducted in combination for this gene regulation study. It was determined that PhoP and RovA recognized the promoter-proximal regions of psaEF and psaABC in order to repress and stimulate their transcription, respectively. The translation/transcription start sites, Shine-Dalgarno sequences (ribosomal binding site), core promoter -10 and -35 elements, PhoP and RovA sites and PhoP/RovA consensus-like sequences were identified to determine the structural organization of PhoP/RovA-dependent promoters of psaEF and psaABC. RovA stimulated psaEF and psaABC, while PhoP repressed these two operons involving the direct association between RovA/PhoP and target promoter regions. The reciprocal regulation of psa genes by PhoP and RovA could contribute to the tightly controlled expression of the pH 6 antigen during infection.