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.