Motor torque measurement of Halobacterium salinarum archaellar suggests a general model for ATP-driven rotary motors.

Autor: Iwata S; 1Department of Physics, Gakushuin University, 1-5-1 Mejiro, Toshima-ku, Tokyo, 171-8588 Japan., Kinosita Y; 1Department of Physics, Gakushuin University, 1-5-1 Mejiro, Toshima-ku, Tokyo, 171-8588 Japan., Uchida N; 2Department of Physics, Tohoku University, Sendai, 980-8578 Japan., Nakane D; 1Department of Physics, Gakushuin University, 1-5-1 Mejiro, Toshima-ku, Tokyo, 171-8588 Japan., Nishizaka T; 1Department of Physics, Gakushuin University, 1-5-1 Mejiro, Toshima-ku, Tokyo, 171-8588 Japan.
Jazyk: angličtina
Zdroj: Communications biology [Commun Biol] 2019 May 24; Vol. 2, pp. 199. Date of Electronic Publication: 2019 May 24 (Print Publication: 2019).
DOI: 10.1038/s42003-019-0422-6
Abstrakt: It is unknown how the archaellum-the rotary propeller used by Archaea for motility-works. To further understand the molecular mechanism by which the hexameric ATPase motor protein FlaI drives rotation of the membrane-embedded archaellar motor, we determined motor torque by imposition of various loads on Halobacterium salinarum archaella. Markers of different sizes were attached to single archaella, and their trajectories were quantified using three-dimensional tracking and high-speed recording. We show that rotation slows as the viscous drag of markers increases, but torque remains constant at 160 pN·nm independent of rotation speed. Notably, the estimated work done in a single rotation is twice the expected energy that would come from hydrolysis of six ATP molecules in the hexamer, indicating that more ATP molecules are required for one rotation of archaellum. To reconcile the apparent contradiction, we suggest a new and general model for the mechanism of ATP-driven rotary motors.
Competing Interests: Competing interestsThe authors declare no competing interests.
Databáze: MEDLINE
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