Identification of a mutation in Escherichia coli F1‐ATPase β‐subunit conferring resistance to aurovertin

Abstract

A mutation conferring aurovertin resistance on Escherichia coli F₁-ATPase was identified as R398 → in the F₁ β-subunit. β-subunit from the mutant doe not bind aurovertin; therefore our results suggest the region of sequence around residue β-398 is involved in aurovertin binding. Since nucleotide and aurovertin binding to isolated β-subunit are not mutually exclusive, the data further suggest that the β-subunit catalytic nucleotide-binding domain does not include residue 398. The mutation prevented aurovertin inhibition of ATPase at pH 6 and 8.5, implying charge on the arginine side-chain is not a major determinant of aurovertin binding or that the pK of R398 is shifted due to a peculiar environment. The equivalent residue is usually arginine in F₁ β-subunits of different species; notably in the aurovertin-insensitive thermophilic bacterium PS3 F₁-ATPase, this residue is phenylalanine.