Post-Genomic Insights into the Regulation of Transcription in the Facultative Intracelluar Pathogen Listeria monocytogenes (pp. 617-642
Authors: (Sinéad Heavin, and Conor P. O’Byrne,School of Natural Sciences, Galway, Ireland)
Abstract: Bacteria respond and adapt to changing environmental conditions by regulating the expression of their genes in an appropriate manner. To be effective this regulation must be rapid, sensitive, and specific to the conditions encountered. Listeria monocytogenes is a highly adaptable facultative intracellular pathogen that can thrive in a diverse range of environments both outside and within the host. It has evolved sophisticated molecular mechanisms to invade cells within the host and to spread from cell to cell. Activation of these mechanisms requires the appropriate deployment of a set of virulence genes whose expression is largely under the control of a transcriptional regulator, PrfA. Growth and survival of L. monocytogenes in harsh environments, both in the gastrointestinal tract and outside of the host, requires the expression of specific sets of genes that confer stress protection and increase the likelihood of survival. The sigma factor SigB (ζB) plays a key role in directing the transcription of these protective functions. L. monocytogenes is motile at temperatures of 30ºC and below but non-motile at 37ºC. Motility is a complex phenotype that is energetically expensive, involves the expression of many genes, and is a distinct disadvantage within the host where flagella can stimulate the host immune system.