The Flagellar Motor of Undergoes Major Structural Remodeling During Rotational Switching

Overview

Journal Elife

Specialty Biology

Date 2020 Sep 7

PMID 32893817

Citations 30

Authors

Brittany L Carroll

Tatsuro Nishikino

Wangbiao Guo

Shiwei Zhu

Seiji Kojima

Michio Homma

Jun Liu

Affiliations

Soon will be listed here.

Abstract

The bacterial flagellar motor switches rotational direction between counterclockwise (CCW) and clockwise (CW) to direct the migration of the cell. The cytoplasmic ring (C-ring) of the motor, which is composed of FliG, FliM, and FliN, is known for controlling the rotational sense of the flagellum. However, the mechanism underlying rotational switching remains elusive. Here, we deployed cryo-electron tomography to visualize the C-ring in two rotational biased mutants in . We determined the C-ring molecular architectures, providing novel insights into the mechanism of rotational switching. We report that the C-ring maintained 34-fold symmetry in both rotational senses, and the protein composition remained constant. The two structures show FliG conformational changes elicit a large conformational rearrangement of the rotor complex that coincides with rotational switching of the flagellum. FliM and FliN form a stable spiral-shaped base of the C-ring, likely stabilizing the C-ring during the conformational remodeling.

Citing Articles

Regulatory Role of a Hydrophobic Core in the FliG C-Terminal Domain in the Rotary Direction of a Flagellar Motor.

Nishikino T, Hatano A, Kojima S, Homma M Biomolecules. 2025; 15(2).

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Ultrasensitivity without conformational spread: A mechanical origin for non-equilibrium cooperativity in the bacterial flagellar motor.

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PMID: 39793078 PMC: 11725899. DOI: 10.1073/pnas.2412594121.

The big chill: Growth of structural biology with cryo-electron tomography.

Kudryashev M QRB Discov. 2024; 5:e10.

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