Regulation of RamA by RamR in Salmonella entericaSerovar Typhimurium: Isolation of a RamR Superrepressor

ABSTRACTRamA is a transcription factor involved in regulating multidrug resistance in Salmonella entericaserovar Typhimurium SL1344. Green fluorescent protein (GFP) reporter fusions were exploited to investigate the regulation of RamA expression by RamR. We show that RamR represses the ramApromoter by binding to a palindromic sequence and describe a superrepressor RamR mutant that binds to the ramApromoter sequence more efficiently, thus exhibiting a ramAinactivated phenotype.