Mutations in the dimerization domain of the b subunit from the Escherichia coli ATP synthase. Deletions disrupt function but not enzyme assembly

The Journal of Biological Chemistry
Daniel J CiprianoS D Dunn

Abstract

The b subunit dimer of Escherichia coli ATP synthase serves essential roles as an assembly factor for the enzyme and as a stator during rotational catalysis. To investigate the functional importance of its coiled coil dimerization domain, a series of internal deletions including each individual residue between Lys-100 and Ala-105 (b(deltaK100)-b(deltaA105)), b(deltaK100-A103), and b(deltaK100-Q106) as well as a control b(K100A) missense mutation were prepared. All of the mutants supported assembly of ATP synthase, but all single-residue deletions failed to support growth on acetate, indicating a severe defect in oxidative phosphorylation, and b(deltaK100-Q106) displayed moderately reduced growth. The membrane-bound ATPase activities of these strains showed a related reduction in sensitivity to dicyclohexylcarbodiimide, indicative of uncoupling. Analysis of dimerization of the soluble constructs of b(deltaK100) and the multiple-residue deletions by sedimentation equilibrium revealed reduced dimerization compared with wild type for all deletions, with b(deltaK100-Q106) most severely affected. In cross-linking studies it was found that F1-ATPase can mediate the dimerization of some soluble b constructs but did not mediate dimeriza...Continue Reading

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Citations

Oct 10, 2006·Journal of Molecular Biology·Paul A Del RizzoStanley D Dunn
Jun 3, 2008·Biochimica Et Biophysica Acta·Benjamin Varco-MerthPetra Fromme
Sep 21, 2018·Frontiers in Physiology·Lilia Colina-TenorioDiego González-Halphen
Nov 12, 2021·Frontiers in Bioengineering and Biotechnology·Yu-Sin JangSang Yup Lee

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