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Tight Chemomechanical Coupling of the F₁ Motor Relies on Structural Stability.

ABSTRACT: The F₁ motor is a rotating molecular motor that ensures a tight chemomechanical coupling between ATP hydrolysis/synthesis reactions and rotation steps. However, the mechanism underlying this tight coupling remains to be elucidated. In this study, we used electrorotation in single-molecule experiments using an F₁βE190D mutant to demonstrate that the stall torque was significantly smaller than the wild-type F₁, indicating a loose coupling of this mutant, despite showing similar stepping torque as the wild-type. Experiments on the ATPase activity after heat treatment and gel filtration of the α₃β₃-subcomplex revealed the unstable structure of the βE190D mutant. Our results suggest that the tight chemomechanical coupling of the F₁ motor relies on the structural stability of F₁. We also discuss the difference between the stepping torque and the stall torque.

SUBMITTER: Tanaka M

PROVIDER: S-EPMC7335906 | biostudies-literature | 2020 Jul

REPOSITORIES: biostudies-literature

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Tight Chemomechanical Coupling of the F1 Motor Relies on Structural Stability.

Tanaka Mana M Kawakami Tomohiro T Okaniwa Tomoaki T Nakayama Yohei Y Toyabe Shoichi S Ueno Hiroshi H Muneyuki Eiro E

Biophysical journal 20200529 1

The F1 motor is a rotating molecular motor that ensures a tight chemomechanical coupling between ATP hydrolysis/synthesis reactions and rotation steps. However, the mechanism underlying this tight coupling remains to be elucidated. In this study, we used electrorotation in single-molecule experiments using an F1βE190D mutant to demonstrate that the stall torque was significantly smaller than the wild-type F1, indicating a loose coupling of this mutant, despite sh ...[more]

PMID: 32531205

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