Mutations altering aspartyl-61 of the omega subunit (uncE protein) of Escherichia coli H super(+)-ATPase differ in effect on coupled ATP hydrolysis

Mutations in the H super(+)-translocating ATPase complex (F sub(1)F sub(0)) of E. coli) have been described in which aspartyl-61 of the omega subunit (uncE protein) is substituted by either glycine (uncE105) or asparagine (uncE107). Either substitution blocks the H super(+)-translocation activity of...

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Bibliographic Details
Published in:Journal of bacteriology 1984-01, Vol.158 (3), p.1078-1083
Main Authors: Fillingame, R H, Peters, L K, White, L K, Mosher, ME, Paule, C R
Format: Article
Language:English
Subjects:
adenosinetriphosphatase
ATP
Escherichia coli
hydrolysis
mutation
protons
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Summary:Mutations in the H super(+)-translocating ATPase complex (F sub(1)F sub(0)) of E. coli) have been described in which aspartyl-61 of the omega subunit (uncE protein) is substituted by either glycine (uncE105) or asparagine (uncE107). Either substitution blocks the H super(+)-translocation activity of the F sub(0) sector of the complex. Here the authors report a difference in the effects of the two substitutions on the coupled ATPase activity of F sub(1) bound to F sub(0). Wild-type F sub(1) was bound to the F sub(0) of either mutant with affinities comparable to wild-type. The ATPase activity of F sub(1) bound to uncE107 F sub(0) was inhibited by 50% whereas that to uncE105 F sub(0) was not inhibited. Complementation studies with a pBR322-derived plasmid that carried the E gene of the unc) operon only indicated that a single mutation in the host strain was responsible for the respective phenotypes. The results indicate that a glycine-versus-asparagine substitution for aspartyl-61 must lead to altered conformations of omega and that these differences in conformation are important in the coupling between the F sub(0) and F sub(1) sectors of the complex.
ISSN:0021-9193