Transcriptomic and Phenotypic Analyses Suggest a Network between the Transcriptional Regulators HrcA and σBinListeria monocytogenes

Publisher Website
Google Scholar
Abstract
Listeria monocytogenesHrcA and CtsR negatively regulate class I and III stress response genes, respectively, while σBpositively regulates the transcription of class II stress response genes. To define the HrcA regulon and identify interactions between HrcA, CtsR, and σB, we characterized newly generatedL. monocytogenesΔhrcA, ΔctsRΔhrcA, and ΔhrcAΔsigBstrains, along with previously described ΔsigB, ΔctsR, and ΔctsRΔsigBstrains, using phenotypic assays (i.e., heat resistance, acid resistance, and invasion of human intestinal epithelial cells) and performed whole-genome transcriptome analysis of the ΔhrcAstrain. ThehrcAandsigBdeletions had significant effects on heat resistance. While thehrcAdeletion had no significant effect on acid resistance or invasion efficiency in Caco-2 cells, a linear regression model revealed a significant (P= 0.0493) effect of interactions between thehrcAdeletion and thectsRdeletion on invasiveness. Microarray-based transcriptome analyses and promoter searches identified (i) 25 HrcA-repressed genes, including two operons (thegroESLanddnaKoperons, both confirmed as HrcA regulated by quantitative real-time PCR) and one gene directly repressed by HrcA, and (ii) 36 genes that showed lower transcript levels in the ΔhrcAstrain and thus appear to be indirectly upregulated by HrcA. A number of genes were found to be coregulated by either HrcA and CtsR (2 genes), HrcA and σB(31 genes), or all three regulators (5 genes, e.g.,gadCB). Combined with previous evidence that σBappears to directly regulatehrcAtranscription, our data suggest that HrcA and σB, as well as CtsR, form a regulatory network that contributes to the transcription of a number ofL. monocytogenesgenes.

This publication has 58 references indexed in Scilit: