Submitted to: American Society for Microbiology Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 5/23/2004
Publication Date: 5/27/2004
Citation: Navarre, W.W., Halsey, T.A., Walthers, D., Frye, J.G., Mcclelland, M., Potter, J.L., Kenney, L., Gunn, J., Fang, F.C., Libby, S.J. 2004. Apparent regulation of slya specificity by phop in salmonella enterica. American Society for Microbiology Meeting. B-215.
Technical Abstract: The Salmonella enterica transcriptional regulatory proteins PhoP and SlyA have both been implicated in the control of genes required for virulence and survival within host macrophages. We have investigated the regulatory relationship between PhoP and SlyA using cDNA microarray, real-time PCR, and biochemical assays. A cDNA microarray analysis of the PhoP and SlyA regulons has demonstrated a number of loci requiring both PhoP and SlyA for expression, including pagC, pagK, and mig-14. Gel mobility-shift and DNA footprinting analyses indicate that purified SlyA protein, but not phosphorylated-PhoP, binds to the pagC and mig-14 promoters, suggesting that SlyA is the proximal regulator of these genes and that PhoP regulates these genes by activating SlyA. Under some conditions, a phoP mutation can be shown to exert a modest effect on slyA expression. However, PhoP-dependent effects on pagC mRNA abundance can be shown to occur under conditions in which the abundance of slyA transcript remains unaltered. Moreover, a phoP mutation does not abolish slyA expression. A slyA mutation affects the expression of multiple loci in both phoP null and phoQ-24 “phoP constitutive” backgrounds, but the identity of the slyA-regulated loci differs depending on whether the PhoPQ pathway is active. These observations suggest that PhoP can influence not only the expression of SlyA, but also its specificity. Further investigation will be required to determine whether this might result from PhoPQ-dependent modification of SlyA or from regulated abundance of a co-activator molecule that affects SlyA conformation, as has been demonstrated in the related transcription factor MarR.