ATP MUTANTS OF ESCHERICHIA-COLI FAIL TO GROW ON SUCCINATE DUE TO A TRANSPORT DEFICIENCY

Escherichia coli atp mutants, which lack a functional Hf-ATPase comple x, are capable of growth on glucose but not on succinate or other C-4- dicarboxylates (Suc(-) phenotype). Suc(+) revertants of an atp deletio n strain were isolated which were capable of growth on succinate even though they lack the entire Hf-ATPase complex. Complementation in tran s with the yhiF gene suppressed the growth of the Suc(+) mutants on su ccinate, which implicates the yhiF gene product in the regulation of C -4-dicarboxylate metabolism. Indeed, when the E. coli C-4-dicarboxylat e transporter (encoded by the dctA gene) was expressed in trans, the S uc(-) phenotype of the atp deletion strain reverted to Suc(+), which s hows that the reason why the E. coli atp mutant is unable to grow aero bically on C-4-dicarboxylates is insufficient transport capacity for t hese substrates.