The flagellar motor of<i>Vibrio alginolyticus</i>undergoes major structural remodeling during rotational switching

Li, Jun; Carroll, Brittany L.; Nishikino, Tatsuro; Guo, Wangbiao; Zhu, S. J.; Kojima, Seiji; Homma, Michio

doi:10.1101/2020.04.24.060053

Cited by 3 publications

(5 citation statements)

References 81 publications

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“…A spiral is created at the base of the C-ring by alternating FliM C -FliN heterodimers and FliN-FliN homodimers (Fig. 4 c, d ), in which FliG2:FliM:FliN exist in a 1:1:3 stoichiometry as proposed previously 28,29 . The switch complex seen in the Δ cheY3 -Class-2 motor represents the conformation associated with the CCW rotational state (Fig.…”

Section: Resultsmentioning

confidence: 65%

Molecular Mechanism for Rotational Switching of the Bacterial Flagellar Motor

Chang

Zhang

Carroll

et al. 2020

Preprint

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23The bacterial flagellar motor is a remarkable nanomachine that can rapidly rotate in both 24 counter-clockwise (CCW) and clockwise (CW) senses. The transitions between CCW and CW 25 rotation are critical for chemotaxis, and they are controlled by a signaling protein (CheY-P) 26 that interacts with a switch complex at the cytoplasmic side of the flagellar motor. However, 27 the exact molecular mechanism by which CheY-P controls the motor rotational switch remains 28 enigmatic. Here, we use the Lyme disease spirochete, Borrelia burgdorferi, as the model 29 system to dissect the mechanism underlying flagellar rotational switching. We first determined 30 high resolution in situ motor structures in the cheX and cheY3 mutants in which motors are 31 genetically locked in CCW or CW rotation. The structures showed that the CheY3 protein of 32 B. burgdorferi interacts directly with the FliM protein of the switch complex in a 33 phosphorylation-dependent manner. The binding of CheY3-P to FliM induces a major 34 remodeling of the switch protein FliG2 that alters its interaction with the torque generator. 35Because the remodeling of FliG2 is directly correlated with the rotational direction, our data 36 lead to a model for flagellar function in which the torque generator rotates in response to an 37 inward flow of H + driven by the proton motive force. Rapid conformational changes of FliG2 38 allow the switch complex to interact with opposite sides of the rotating torque generator, 39 thereby facilitating rotational switching between CW and CCW. 40 assembling the collar, stator complexes, and C-ring together, we revealed a complex 130 architecture of the CW-rotating flagellar motor with unprecedented details (Fig. 1h, i). 131 132 CheY3-P binds to the FliM protein of the C-ring 133The well-defined C-ring in the ∆cheX mutant was found to be associated with two previously 134 unidentified densities (arrowheads indicated in Fig. 1d, e). We hypothesized that these 135 densities represent bound CheY3-P, as high levels of CheY3-P are expected in the ∆cheX 136 cells 14 . To characterize CheY3-P and its interaction with the ∆cheX motor, we replaced the 137 cheX-cheY3 genes with cheY3-gfp, generating a cheX::cheY3-GFP mutant (Extended Data Fig. 138

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Section: Resultsmentioning

confidence: 65%

Molecular Mechanism for Rotational Switching of the Bacterial Flagellar Motor

Chang

Zhang

Carroll

et al. 2020

Preprint

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“…A spiral is created at the base of the C-ring by alternating FliMC-FliN heterodimers and FliN-FliN homodimers (Fig. 4c, d), in which FliG2:FliM:FliN exist in a 1:1:3 stoichiometry as proposed previously 28,29 . The switch complex seen in the ΔcheY3-Class-2 motor represents the conformation associated with the CCW rotational state (Fig.…”

Section: Chey3-p Binding Triggers Major Remodeling Of Flig2mentioning

confidence: 66%

Molecular mechanism for rotational switching of the bacterial flagellar motor

Chang

Zhang

Carroll

et al. 2020

Nat Struct Mol Biol

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The bacterial flagellar motor is a remarkable nanomachine that can rapidly rotate in both counter-clockwise (CCW) and clockwise (CW) senses. The transitions between CCW and CW rotation are critical for chemotaxis, and they are controlled by a signaling protein (CheY-P) that interacts with a switch complex at the cytoplasmic side of the flagellar motor. However, the exact molecular mechanism by which CheY-P controls the motor rotational switch remains enigmatic. Here, we use the Lyme disease spirochete, Borrelia burgdorferi, as the model system to dissect the mechanism underlying flagellar rotational switching. We first determined high resolution in situ motor structures in the cheX and cheY3 mutants in which motors are genetically locked in CCW or CW rotation. The structures showed that the CheY3 protein of B. burgdorferi interacts directly with the FliM protein of the switch complex in a phosphorylation-dependent manner. The binding of CheY3-P to FliM induces a major remodeling of the switch protein FliG2 that alters its interaction with the torque generator.Because the remodeling of FliG2 is directly correlated with the rotational direction, our data lead to a model for flagellar function in which the torque generator rotates in response to an inward flow of H + driven by the proton motive force. Rapid conformational changes of FliG2 allow the switch complex to interact with opposite sides of the rotating torque generator, thereby facilitating rotational switching between CW and CCW.

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“…The recent MotAB structures, along with cryo-electron tomography (ET) of entire BFMs in situ (Zhao et al, 2013;Carroll et al, 2020), have overturned previous ideas about how the BFM works. The new picture is that energy transduction from the ion motive force to torque occurs entirely within the MotAB stator units, which act as small wheels to rotate the much larger C-ring.…”

Section: Motab Bacterial Flagellar Motormentioning

confidence: 99%

“…In other species other ions replace H + ; for example, Vibrio alginolyticus has Na + -driven stator units called PomA 5 B 2 . Stator units are now believed to rotate unidirectionally, pushing a ring of FliG on the periphery of the C-ring via either their proximal or distal parts (relative to the rotation axis of the entire BFM) to drive CCW or CW rotation, respectively (Carroll et al, 2020). The overall structure and mechanism of the BFM are discussed further below and illustrated in Figure 1.…”

Section: Structures Of Ion-driven 5:2 Rotary Motors Motabmentioning

confidence: 99%

“…In B. burgdorferi (Chang et al, 2020), CW motor rotation is associated with increased radius at the top of the C-ring, implying CW rotation of MotA 5 (Figure 1B). But in Vibrio alginolyticus (Carroll et al, 2020), the change in C-ring radius associated with directional switching is too small to span MotA 5 , as required by the B. burgdorferi model. Furthermore, a FliF-G fusion-deletion mutant of Salmonella enterica, with a C-ring of reduced diameter and no apparent space for interactions between FliG and the distal part of MotA (Sakai et al, 2019), rotates CW.…”

Section: Motab Bacterial Flagellar Motormentioning

confidence: 99%

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A new class of biological ion-driven rotary molecular motors with 5:2 symmetry

et al. 2022

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Several new structures of three types of protein complexes, obtained by cryo-electron microscopy (cryo-EM) and published between 2019 and 2021, identify a new family of natural molecular wheels, the “5:2 rotary motors.” These span the cytoplasmic membranes of bacteria, and their rotation is driven by ion flow into the cell. They consist of a pentameric wheel encircling a dimeric axle within the cytoplasmic membrane of both Gram-positive and gram-negative bacteria. The axles extend into the periplasm, and the wheels extend into the cytoplasm. Rotation of these wheels has never been observed directly; it is inferred from the symmetry of the complexes and from the roles they play within the larger systems that they are known to power. In particular, the new structure of the stator complex of the Bacterial Flagellar Motor, MotA5B2, is consistent with a “wheels within wheels” model of the motor. Other 5:2 rotary motors are believed to share the core rotary function and mechanism, driven by ion-motive force at the cytoplasmic membrane. Their structures diverge in their periplasmic and cytoplasmic parts, reflecting the variety of roles that they perform. This review focuses on the structures of 5:2 rotary motors and their proposed mechanisms and functions. We also discuss molecular rotation in general and its relation to the rotational symmetry of molecular complexes.

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The flagellar motor ofVibrio alginolyticusundergoes major structural remodeling during rotational switching

Cited by 3 publications

References 81 publications

Molecular Mechanism for Rotational Switching of the Bacterial Flagellar Motor

Molecular Mechanism for Rotational Switching of the Bacterial Flagellar Motor

Molecular mechanism for rotational switching of the bacterial flagellar motor

A new class of biological ion-driven rotary molecular motors with 5:2 symmetry

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