Identification of an uncoupling mutation affecting the b subunit of F1F0 ATP synthase in Escherichia coli.
A specific b subunit arginine, b(Arg-36) in Escherichia coli, displays evolutionary conservation among bacterial F1F0 ATP synthases. Site-directed mutagenesis was used to generate a collection of mutations affecting b(Arg-36). The phenotype differed depending upon the substitution, and the b(Arg-36-Glu) and b(Arg-36-Ile) substitutions virtually abolished enzyme function. Although the total amounts of F1F0 ATP synthase present in the membranes prepared from mutant strains were reduced, the primary effect of the b(Arg-36) substitutions was on the activities of the intact enzyme complexes. The most interesting result was that the b(Arg-36-Glu) substitution results in the uncoupling of a functional F0 from F1 ATP hydrolysis activity.
Caviston
T L
TL
Department of Biochemistry and Molecular Biology, University of Florida, Gainesville 32610, USA.
Ketchum
C J
CJ
Sorgen
P L
PL
Nakamoto
R K
RK
Cain
B D
BD
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D025243:Bacterial Proton-Translocating ATPases; D004926:Escherichia coli / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development; D029968:Escherichia coli Proteins; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D006180:Proton-Translocating ATPases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C074430:uncF protein, E coli; D025243:Bacterial Proton-Translocating ATPases; D006180:Proton-Translocating ATPases