AEROBIC AND ANAEROBIC REGULATION OF THE UBICA OPERON, ENCODING ENZYMES FOR THE FIRST 2 COMMITTED STEPS OF UBIQUINONE BIOSYNTHESIS IN ESCHERICHIA-COLI

The ubiCA operon of Escherichia coli encodes enzymes for the first two steps of ubiquinone biosynthesis, A monolysogen (ubiC-lacZ operon fus ion) was constructed to study ubiCA regulation, Expression was higher during aerobic growth than anaerobically, and increased with rate of o xygen supply, Although ubiquinone is implicated in antioxidant roles, ubiC expression was not elevated in response to hydrogen peroxide or t he redox cycling agent, paraquat, Glucose repressed expression and mut ation of cya (encoding adenylate cyclase) increased expression, Anaero bically utilised electron accepters (nitrite, nitrate, fumarate) did n ot affect expression, ubiC expression appears to be negatively regulat ed by Fm and IHF. (C) 1997 Federation of European Biochemical Societie s.