Isolation of Escherichia coli mutants with an adenosine triphosphatase insensitive to aurovertin

Energy-transducing adenosine triphosphatase (ATPase) from Escherichia coli is inhibited by aurovertin. Aurovertin-resistant mutants were generated by nitrosoguanidine mutagenesis of E. coli AN180, whose growth on a nonfermentable carbon source was blocked by aurovertin. The ATPase activity of cell extracts from 15 different mutants (designated MA1, MA2, MA3, etc.) was found to be at least 20 times less sensitive to aurovertin than that from the parent strain. The aurovertin-resistant mutants did not show cross-resistance towards a number of ATPase inhibitors including azide, dicyclohexylcarbodiimide, quercetin, 7-chloro-4-nitrobenzofurazan, and N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline. Aurovertin inhibited the energization brought about by addition of ATP to E. coli AN180 membrane vesicles; it was without effect on MA1 and MA2 membrane vesicles energized by ATP. The mutation in MA1, like other mutations of the ATPase complex, maps in the unc region of the bacterial chromosome.