Graduate Programs in the Life Sciences

Research Focus

• Research in our lab seeks to understand the environmental cues of the intestinal tract that induce virulence gene expression in Salmonella. Our work shows that the environment of the intestinal tract affects Salmonella virulence in a complex way: Conditions of the ileum, where Salmonella normally invades, promote the expression of genes required for virulence, while colonic conditions have the opposite effect. Our work therefore examines how changes in the environment of the intestine affect the virulence of Salmonella. We are also attempting to define the genetic pathways by which environmental signals are communicated in Salmonella to cause changes in virulence gene expression. We have demonstrated that a two-component regulator, BarA/SirA, controls a post-transcriptional regulatory system consisting of a small regulator protein, CsrA, and two untranslated RNA molecules, CsrB and CsrC, which in turn controls invasion and other functions. We have further shown that specific short chain fatty acids, natural products of the intestinal microbiota, can alter invasion through this pathway. We are presently using genetic and genomic approaches to characterize this regulon.