Authors: Amanda K Welch Shane B Claggett Brian D Cain
Publish Date: 2008/01/19
Volume: 40, Issue: 1, Pages: 1-8
Abstract
In Escherichia coli the F1FO ATP synthase b subunits house a conserved arginine in the tether domain at position 36 where the subunit emerges from the membrane Previous experiments showed that substitution of isoleucine or glutamate result in a loss of enzyme activity Double mutants have been constructed in an attempt to achieve an intragenic suppressor of the b arg36→ile and the b arg36→glu mutations The b arg36→ile mutation could not be suppressed In contrast the phenotypic defect resulting from the b arg36→glu mutation was largely suppressed in the b arg36→gluglu39→arg double mutant E coli expressing the b arg36→gluglu39→arg subunit grew well on succinatebased medium F1FO ATP synthase complexes were more efficiently assembled and ATP driven proton pumping activity was improved The evidence suggests that efficient coupling in F1FO ATP synthase is dependent upon a basic amino acid located at the base of the peripheral stalk
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