IDENTIFICATION OF A FATTY ACYL RESPONSIVE REGULATOR (FARR) IN ESCHERICHIA-COLI

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 (g 30) in the citric acid cycle gene cluster of E. coli (gltA-sdhCDAB-suc ABCD-farR). The amplified FarR protein specifically bound to the farR promoter (P-farR and exhibited weak binding to the citrate synthase an d lipoamide dehydrogenase promoters. Binding at P-farR was abolished b y long-chain fatty acids and their CoA thioesters. In DNaseI footprint s, FarR binding at P-farR protected two sites, each characterised by t wo related 10-bp direct repeats. It is suggested that FarR autoregulat es farR expression and may modulate citric acid cycle expression in re sponse to long-chain fatty acids.