Characterization of a large motility gene cluster containing thecheR, motABgenes ofListeria monocytogenesand evidence that PrfA downregulates motility genes

Abstract

Through the analysis of a non-motile mutant of Listeria monocytogenes, we identified and characterized a locus containing the cheR, motA and motB genes. These three genes are homologous to the cheR, and motA/B genes of Bacillus subtilis which in this organism are 954 kb apart. The gene organization in Listeria is also not similar either to that of Escherichia coli in which cheR and motAB are 5.9 kb apart. CheR and motA/B, as previously reported for flaA, the flagellin gene, are thermoregulated with a higher expression at 25°C and low expression at 37°C. In a ΔprfA strain, motA expression was derepressed at 37°C, suggesting that PrfA, the transcriptional activator of virulence genes, downregulates motility genes in Listeria at 37°C.