Comparative Analysis of the Regulation of rovA from the Pathogenic Yersiniae

Abstract

ABSTRACT RovA is a MarR/SlyA-type regulator that mediates the transcription of inv in Yersinia enterocolitica and Y. pseudotuberculosis . In Y. pseudotuberculosis , rovA transcription is controlled primarily by H-NS and RovA, which bind to similar regions within the rovA promoter. At 37°C, rovA transcription is repressed by H-NS. Transcription of rovA results when RovA relieves H-NS-mediated repression. The region of the rovA promoter that H-NS and RovA bind is not conserved in the Y. enterocolitica promoter. Using green fluorescent protein reporters, we determined that the Y. enterocolitica rovA ( rovA Yent ) promoter is weaker than the Y. pseudotuberculosis promoter. However, despite the missing H-NS/RovA binding site in the rovA Yent promoter, H-NS and RovA are still involved in the regulation of rovA Yent . DNA binding studies suggest that H-NS and RovA bind with a higher affinity to the Y. pseudotuberculosis/Y. pestis rovA ( rovA Ypstb/Ypestis ) promoter than to the rovA Yent promoter. Furthermore, H-NS appears to bind to two regions in a cooperative fashion within the rovA Yent promoter that is not observed with the rovA Ypstb/Ypestis promoter. Finally, using a transposon mutagenesis approach, we identified a new positive regulator of rovA in Y. enterocolitica , LeuO. In Escherichia coli , LeuO regulates gene expression via changes in levels of RpoS and H-NS, but LeuO-mediated regulation of rovA Yent appears to be independent of either of these two proteins. Together, these data demonstrate that while the rovA regulatory factors are conserved in Yersinia , divergence of Y. enterocolitica and Y. pseudotuberculosis/Y. pestis during evolution has resulted in modifications in the mechanisms that are responsible for controlling rovA transcription.