期刊
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
卷 109, 期 25, 页码 E1599-E1608出版社
NATL ACAD SCIENCES
DOI: 10.1073/pnas.1120027109
关键词
alpha helix packing; F1Fo ATP synthase; membrane protein; rotary motor stoichiometry; bioenergetics
资金
- Cluster of Excellence Macromolecular Complexes at the Goethe University Frankfurt [EXC 115]
- Collaborative Research Center 807 of the German Research Foundation
- Synthetic Biology: Engineering Complex Biological Systems (EuroSYNBIO)-Nanocell project of the European Science Foundation
ATP synthase membrane rotors consist of a ring of c-subunits whose stoichiometry is constant for a given species but variable across different ones. We investigated the importance of c/c-subunit contacts by site-directed mutagenesis of a conserved stretch of glycines (GxGxGxGxG) in a bacterial c(11) ring. Structural and biochemical studies show a direct, specific influence on the c-subunit stoichiometry, revealing c(<11), c(12), c(13), c(14), and c(>14) rings. Molecular dynamics simulations rationalize this effect in terms of the energetics and geometry of the c-subunit interfaces. Quantitative data from a spectroscopic interaction study demonstrate that the complex assembly is independent of the c-ring size. Real-time ATP synthesis experiments in proteoliposomes show the mutant enzyme, harboring the larger c(12) instead of c(11), is functional at lower ion motive force. The high degree of compliance in the architecture of the ATP synthase rotor offers a rationale for the natural diversity of c-ring stoichiometries, which likely reflect adaptations to specific bioenergetic demands. These results provide the basis for bioengineering ATP synthases with customized ion-to-ATP ratios, by sequence modifications.
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