Modulation of stress and virulence in Listeria monocytogenes

Listeria monocytogenes can respond rapidly to changing environmental conditions, as illustrated by its ability to transition from a saprophyte to an orally transmitted facultative intracellular pathogen. Differential associations between various alternative σ factors and a core RNA polymerase provide a transcriptional mechanism for regulating bacterial gene expression that is crucial for survival in rapidly changing conditions. Alternative σ factors are key components of complex L. monocytogenes regulatory networks that include multiple transcriptional regulators of stress-response and virulence genes, regulation of genes encoding other regulators, and regulation of small RNAs. In this article, the contributions of various σ factors to L. monocytogenes stress response and virulence are described.