Evidence for a Partially Stalled γ Rotor in F1-ATPase from Hydrogen–Deuterium Exchange Experiments and Molecular Dynamics Simulations
| Autor: | Stanley D. Dunn, Siavash Vahidi, Angela M. Murcia Rios, Lars Konermann |
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| Rok vydání: | 2018 |
| Předmět: |
0301 basic medicine
Rotor (electric) Chemistry Kinetics General Chemistry Crystal structure 010402 general chemistry Rotation 01 natural sciences Biochemistry Catalysis 0104 chemical sciences law.invention 03 medical and health sciences Molecular dynamics 030104 developmental biology Colloid and Surface Chemistry law ATP hydrolysis Helix Biophysics Hydrogen–deuterium exchange |
| Zdroj: | Journal of the American Chemical Society. 140:14860-14869 |
| ISSN: | 1520-5126 0002-7863 |
| DOI: | 10.1021/jacs.8b08692 |
| Popis: | F1-ATPase uses ATP hydrolysis to drive rotation of the γ subunit. The γ C-terminal helix constitutes the rotor tip that is seated in an apical bearing formed by α3β3. It remains uncertain to what extent the γ conformation during rotation differs from that seen in rigid crystal structures. Existing models assume that the entire γ subunit participates in every rotation. Here we interrogated E. coli F1-ATPase by hydrogen–deuterium exchange (HDX) mass spectrometry. Rotation of γ caused greatly enhanced deuteration in the γ C-terminal helix. The HDX kinetics implied that most F1 complexes operate with an intact rotor at any given time, but that the rotor tip is prone to occasional unfolding. A molecular dynamics (MD) strategy was developed to model the off-axis forces acting on γ. MD runs showed stalling of the rotor tip and unfolding of the γ C-terminal helix. MD-predicted H-bond opening events coincided with experimental HDX patterns. Our data suggest that in vitro operation of F1-ATPase is associated with s... |
| Databáze: | OpenAIRE |
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