Identification of a fatty acyl responsive regulator (FarR) in Escherichia coli

Abstract FarR (formerly P30) has been identified as a fatty acid and fatty acyl-CoA responsive DNA-binding protein. It is encoded by the farR gene ( g30 ) in the citric acid cycle gene cluster of E. coli ( gltA-sdhCDAB-sucABCD-farR ). The amplified FarR protein specifically bound to the farR promoter ( P farR ) and exhibited weak binding to the citrate synthase and lipoamide dehydrogenase promoters. Binding at P farR was abolished by long-chain fatty acids and their CoA thioesters. In DNaseI footprints, FarR binding at P faR protected two sites each characterised by two related 10-bp direct repeats. It is suggested that farR autoregulates farR expression and may modulate citric acid cycle expression in response to long-chain fatty acids.