EFFECTS OF CARBON SOURCE ON EXPRESSION OF F-0 GENES AND ON THE STOICHIOMETRY OF THE C-SUBUNIT IN THE F1F0 ATPASE OF ESCHERICHIA-COLI

Expression of the genes for the membrane-bound F-0 sector of the Esche richia coli F1F0 proton-translocating ATPase can respond to changes in metabolic conditions, and these changes are reflected in alterations in the subunit stoichiometry of the oligomeric F-0 proton channel, Tra nscriptional and translational lacZ fusions to the promoter and to two F-0 genes show that, during growth on the nonfermentable carbon sourc e succinate, transcription of the operon and translation of uncB, enco ding the a subunit of F-0, are higher than during growth on glucose. I n contrast, translation of the uncE gene, encoding the c subunit of F- 0, is higher during growth on glucose than during growth on succinate, Translation rates of both uncB and uncE change as culture density inc reases, but transcription rates do not. Quantitation of the c stoichio metry shows that more c subunits are assembled into the F1F0 ATPase in cells grown on glucose than in cells grown on succinate, E. coli ther efore appears to have a mechanism for regulating the composition and, presumably, the function of the ATPase in response to metabolic circum stances.