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  Elasticity, friction, and pathway of γ-subunit rotation in FoF1-ATP synthase

Okazaki, K.-i., & Hummer, G. (2015). Elasticity, friction, and pathway of γ-subunit rotation in FoF1-ATP synthase. Proceedings of the National Academy of Sciences of the United States of America, 112(34), 10720-10725. doi: 10.1073/pnas.1500691112.

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 Creators:
Okazaki, Kei-ichi1, Author              
Hummer, Gerhard1, Author              
Affiliations:
1Department of Theoretical Biophysics, Max Planck Institute of Biophysics, Max Planck Society, ou_2068292              

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Free keywords: Bioenergetics; molecular motor; mechanochemical coupling
 Abstract: We combine molecular simulations and mechanical modeling to explore the mechanism of energy conversion in the coupled rotary motors of FoF1-ATP synthase. A torsional viscoelastic model with frictional dissipation quantitatively reproduces the dynamics and energetics seen in atomistic molecular dynamics simulations of torque-driven γ-subunit rotation in the F1-ATPase rotary motor. The torsional elastic coefficients determined from the simulations agree with results from independent single-molecule experiments probing different segments of the γ-subunit, which resolves a long-lasting controversy. At steady rotational speeds of ∼1 kHz corresponding to experimental turnover, the calculated frictional dissipation of less than kBT per rotation is consistent with the high thermodynamic efficiency of the fully reversible motor. Without load, the maximum rotational speed during transitions between dwells is reached at ∼1 MHz. Energetic constraints dictate a unique pathway for the coupled rotations of the Fo and F1 rotary motors in ATP synthase, and explain the need for the finer stepping of the F1 motor in the mammalian system, as seen in recent experiments. Compensating for incommensurate eightfold and threefold rotational symmetries in Fo and F1, respectively, a significant fraction of the external mechanical work is transiently stored as elastic energy in the γ-subunit. The general framework developed here should be applicable to other molecular machines.

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Language(s): eng - English
 Dates: 2015-01-152015-07-162015-08-102015-08-25
 Publication Status: Published in print
 Pages: 6
 Publishing info: -
 Table of Contents: -
 Rev. Type: Peer
 Identifiers: DOI: 10.1073/pnas.1500691112
 Degree: -

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Title: Proceedings of the National Academy of Sciences of the United States of America
  Abbreviation : PNAS
Source Genre: Journal
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Publ. Info: Washington, D.C. : National Academy of Sciences
Pages: - Volume / Issue: 112 (34) Sequence Number: - Start / End Page: 10720 - 10725 Identifier: ISSN: 0027-8424
CoNE: https://pure.mpg.de/cone/journals/resource/954925427230