Figure 1.
Increase of endogenous heme biosynthesis by compound 1 resulting in the accumulation of heme, which activates the heme sensor system (HssRS) through the sensor histidine kinase HssS. HssS autophosphorylates upon activation and transfers the phosphate to its cognate response regulator, HssR. HssR binds to the promoter of hrtAB, a gene encoding the heme regulated transporter (HrtAB) leading to its expression and resulting in alleviation of heme toxicity. Compound 1 also inhibits the growth of bacteria under anaerobic conditions, potentially through inhibition of a process crucial to fermentation. These two activities may or may not be linked through a single target.