Regulation of igaA and the Rcs System by the MviA Response Regulator in Salmonella enterica

IgaA is a membrane protein that prevents overactivation of the Rcs regulatory system in enteric bacteria. Here we provide evidence that igaA is the first gene in a sigma(70)-dependent operon of Salmonella enterica serovar Typhimurium that also includes yrfG, yrfH, and yrfI. We also show that the Lon protease and the MviA response regulator participate in regulation of the igaA operon. Our results indicate that MviA regulates igaA transcription in an RpoS-dependent manner, but the results also suggest that MviA may regulate RcsB activation in an RpoS- and IgaA-independent manner.