Assembly of F0 sector of Escherichia coli H+ ATP synthase. Interdependence of subunit insertion into the membrane.
The F0 sector of the Escherichia coli H+ transporting ATP synthase is composed of a complex of three subunits, each of which traverses the inner membrane. We have studied the interdependence of subunit insertion into the membrane in a series of chromosomal mutants in which the primary mutation prevented insertion of one of the F0 subunits. Subunit insertion was assessed using Western blots of mutant membrane preparations. Subunit b and subunit c were found to insert into the membrane independently of the other two F0 subunits. On the other hand, subunit a was not inserted into membranes that lacked either subunit b or subunit c. The conclusion that subunit a insertion is dependent upon the co-insertion of subunits b and c differs from the conclusion of several studies, where subunits were expressed from multicopy plasmids.
Hermolin
J
J
Department of Biomolecular Chemistry, University of Wisconsin Medical School, Madison 53706.
Fillingame
R H
RH
D002462:Cell Membrane / Q000201:enzymology; D004269:DNA, Bacterial; D004926:Escherichia coli / Q000201:enzymology*; D009154:Mutation; D006180:Proton-Translocating ATPases / Q000235:genetics / Q000378:metabolism*
D004269:DNA, Bacterial; D006180:Proton-Translocating ATPases