Participation of DnaK in expression of genes involved in virulence of Listeria monocytogenes.

DnaK is required for adaptation to environmental stress and is also involved in bacterial growth under normal conditions. To examine whether DnaK plays a role in the expression of genes related to pathogenicity of Listeria monocytogenes, the transcription of flaA, iap and lmaA in a dnaK mutant was analyzed. Northern blot analysis showed that expression of flaA and lmaA mRNAs was reduced in the dnaK mutant, THY-LK1. A reporter assay revealed that transcription of lmaB in the dnaK mutant, LKS01, constructed in this study was lower than that in the parental strain. In contrast, the dnaK mutation had no effect on the transcription of iap. These results suggest that DnaK is involved in the transcription of flaA and lmaB.