A second global regulator gene (arcB) mediating repression of enzymes in aerobic pathways of Escherichia coli.

In Escherichia coli anaerobic growth lowers the basal or induced levels of numerous enzymes associated with aerobic metabolism. Mutations in arcA (dye) at min 0 relieve this pleiotropic anaerobic repression and render the cell sensitive to the redox dye toluidine blue. In this study we identified a second pleiotropic control gene, arcB, at min 69.5. Mutations, including a deletion, in this gene also relieved the anaerobic repression and caused sensitivity to toluidine blue. Mutations in arcA or arcB did not significantly change the catabolite repression of the target phi(sdh-lacZ) operon, in which lacZ is fused to a structural gene for succinate dehydrogenase, nor did the mutations strikingly influence the pattern of excretion products during glucose fermentation. The presence of arcA+ in a multicopy plasmid restored anaerobic repression in arcB mutants, as indicated by the expression of phi(sdh-lacZ). The arcB product might be a sensor protein for the redox or energy state of the arc regulatory system.