Mechanism of hilA repression by 1,2-propanediol consists of two distinct pathways, one dependent on and the other independent of catabolic production of propionate, in Salmonella enterica serovar Typhimurium

A glycerol dehydrogenase gene was selected as a multicopy suppressor rescuing the reduced hilA expression in the Salmonella enterica serovar Typhimurium cpxA mutant. A substrate of the enzyme, 1,2-propanediol, repressed hilA expression. The 1,2-propanediol-mediated repression at 150 mM, but not that at 300 mM, was abrogated by blocking the catabolism producing propionate from 1,2-propanediol.