In vivo evidence for the role of the ε subunit as an inhibitor of the proton-translocating ATPase of Escherichia coli

Abstract

The function of the ε subunit of the Escherichia coli proton-translocating ATPase has been examined by using a mutant defective in the uncC gene. Strains with a defective uncC gene show a reduction in both growth yield and growth rate that is more severe than for other unc mutants; this deleterious effect is shown to be a result of the ATPase activity of the F1 complex which is missing the ε subunit. In addition, the ε-deficient F1 is bound less tightly to the membrane. These data suggest that, in vivo, the ε subunit is capable of inhibiting the ATPase activity of F1 and also functions in the binding of F1 to F0.