Identifying the YesN Regulon of Enterococcus faecalis

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Presenter(s)

Janie Rainer

Abstract or Description

To survive in a mammalian host, Enterococcus faecalis must adapt to changing host nutrient availability. Glucose is a primary carbon source for most microbes including enterococci but is often limited in the host environment requiring utilization of secondary carbon sources. Our lab has shown that as glucose becomes limiting, E. faecalis adapts its transcriptional profile to take advantage of host N-linked glycoproteins. One notable expression change in this transcriptional analysis comprised a predicted 6 gene operon that includes the response regulator, YesN. YesN shares amino acid sequence conservation with a homologous YesN in Streptococcus pneumoniae, shown to regulate expression of ~ 50 genes. It is thus hypothesized that the E. faecalis YesN regulon regulates a larger suite of genes than is currently known. In order to identify what genes are regulated by YesN, we constructed a genetic deletion mutant of EF0938, a putative ATP hydrolase predicted to be involved in host glycan transport. Using a luciferase reporter plasmid, we demonstrated that in the absence of ef0938, and upon glucose depletion that E. faecalis strongly activates the promoter expression from ef2223, the first gene in the operon that includes the yesN gene. Importantly, this activation was shown to be entirely dependent on YesN, as a yesN mutant fails to activate ef2223 promoter expression. Messenger mRNA from both the ef0938 mutant and the double mutant ef0938 and yesN grown to stationary phase in rich medium was sequenced to identify genes dependent on YesN. Results of this analysis will be discussed.

Mentor

Dr. Lynn Hancock