Structural gene coding for the dicyclohexylcarbodiimide-binding protein of the proton-translocating ATPase from escherichia coli: Locus of the gene in the F 1F 0 gene cluster

Abstract

The proton-translocating ATPase (F,-F,) is an apparatus for the synthesis of ATP common to different energy-transducing organelles, such as mitochondria, chloroplasts and bacterial cytoplasmic membranes (reviews [l-4] ). The ATPase consists of two portions, F, and F,. F, is a peripheral membrane component with 5 different subunits (cw,P.rJ ,E), and it is bound to the integral membrane component, Fo, which functions as a proton pathway. Two or more subunits have been found in F, from different sources. The proteolipid subunits, dicyclohexylcarbodiimide (DCCD)-binding proteins, have been purified from several organisms [2,5,6] and their primary sequences have been determined [7]. Two types of E. coli mutant of this subunit, which both result in inability to bind DCCD, have been reported; the F, of mutant strain DG7/1 is defective in proton translocation [8,9], whereas that of the other type of mutant RF7 [lo] is normal. Thus DG7/1 cannot grow with succinate as the sole carbon source because of defective oxidative phosphorylation, whereas RF7 can grown normally. Both mutant strains have functional F,, although their membrane ATPase activities are not sensitive to DCCD because the mutant protein cannot bind this compound. DCCD binds to an aspartyl residue at position 61 of the polypeptide, and this residue is replaced by a glytine residue in the protein of DG7/1 [8,9]. It has not been shown directly whether these mutations are in