Investigation of the regulation of the rhs locus in Salmonella enterica serovar Typhimurium

Abstract: The rearrangement hotspot (rhs) loci were discovered over thirty years ago, but it was only recently that the Rhs proteins were found to have the capacity to mediate Contact-Dependent growth Inhibition (CDI) of related bacterial species. However, the regulation of the rhs loci has been poorly understood. In this study the regulation of the rhs locus in the pathogen Salmonella enterica serovar Typhimurium (S.tm.) was investigated in infection-relevant conditions. A set of plasmid transcriptional fusions of different rhs promoters to YFP was used to analyse the activities of the promoters in wild type and in S.tm. regulatory mutants. An internal rhs transcript was shown to be expressed and at different levels within the bacterial population. Furthermore, it was found to be regulated by the virulence factors RpoS and HilD.