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Takahashi K, Nishikino T, Kajino H, Kojima S, Uchihashi T, Homma M. Ring formation by Vibrio fusion protein composed of FliF and FliG, MS-ring and C-ring component of bacterial flagellar motor in membrane. Biophys Physicobiol 2023; 20:e200028. [PMID: 38496245 PMCID: PMC10941966 DOI: 10.2142/biophysico.bppb-v20.0028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Accepted: 06/05/2023] [Indexed: 03/19/2024] Open
Abstract
The marine bacterium Vibrio alginolyticus has a single flagellum as a locomotory organ at the cell pole, which is rotated by the Na+-motive force to swim in a liquid. The base of the flagella has a motor composed of a stator and rotor, which serves as a power engine to generate torque through the rotor-stator interaction coupled to Na+ influx through the stator channel. The MS-ring, which is embedded in the membrane at the base of the flagella as part of the rotor, is the initial structure required for flagellum assembly. It comprises 34 molecules of the two-transmembrane protein FliF. FliG, FliM, and FliN form a C-ring just below the MS-ring. FliG is an important rotor protein that interacts with the stator PomA and directly contributes to force generation. We previously found that FliG promotes MS-ring formation in E. coli. In the present study, we constructed a fliF-fliG fusion gene, which encodes an approximately 100 kDa protein, and the successful production of this protein effectively formed the MS-ring in E. coli cells. We observed fuzzy structures around the ring using either electron microscopy or high-speed atomic force microscopy (HS-AFM), suggesting that FliM and FliN are necessary for the formation of a stable ring structure. The HS-AFM movies revealed flexible movements at the FliG region.
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Affiliation(s)
- Kanji Takahashi
- Department of Physics, Nagoya University, Nagoya, Aichi 464-8602, Japan
| | - Tatsuro Nishikino
- Institute for protein research, Osaka University, Suita, Osaka 565-0871, Japan
- Present address: Department of Materials Science and Engineering, Nagoya Institute of Technology, Nagoya Aichi 466-8555, Japan
| | - Hiroki Kajino
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Aichi 464-8602, Japan
| | - Seiji Kojima
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Aichi 464-8602, Japan
| | - Takayuki Uchihashi
- Department of Physics, Nagoya University, Nagoya, Aichi 464-8602, Japan
- Institute for Glyco-core Research (iGCORE), Nagoya University, Nagoya, Aichi 464-0814, Japan
- Department of Creative Research, Exploratory Research Center on Life and Living Systems, National Institutes of Natural Sciences, Okazaki, Aichi 444-8787, Japan
| | - Michio Homma
- Department of Physics, Nagoya University, Nagoya, Aichi 464-8602, Japan
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Aichi 464-8602, Japan
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Nord AL, Biquet-Bisquert A, Abkarian M, Pigaglio T, Seduk F, Magalon A, Pedaci F. Dynamic stiffening of the flagellar hook. Nat Commun 2022; 13:2925. [PMID: 35614041 PMCID: PMC9133114 DOI: 10.1038/s41467-022-30295-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Accepted: 04/22/2022] [Indexed: 11/09/2022] Open
Abstract
For many bacteria, motility stems from one or more flagella, each rotated by the bacterial flagellar motor, a powerful rotary molecular machine. The hook, a soft polymer at the base of each flagellum, acts as a universal joint, coupling rotation between the rigid membrane-spanning rotor and rigid flagellum. In multi-flagellated species, where thrust arises from a hydrodynamically coordinated flagellar bundle, hook flexibility is crucial, as flagella rotate significantly off-axis. However, consequently, the thrust applies a significant bending moment. Therefore, the hook must simultaneously be compliant to enable bundle formation yet rigid to withstand large hydrodynamical forces. Here, via high-resolution measurements and analysis of hook fluctuations under dynamical conditions, we elucidate how it fulfills this double functionality: the hook shows a dynamic increase in bending stiffness under increasing torsional stress. Such strain-stiffening allows the system to be flexible when needed yet reduce deformation under high loads, enabling high speed motility. Bacterial motility relies on the mechanics of the “hook” the 60 nm biopolymer at the base of rotating flagella. Here, authors observe the hook stiffening as it is twisted by the rotation of the flagellum, a mechanical feat evolved for its function.
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Affiliation(s)
- Ashley L Nord
- Centre de Biologie Structurale, Univ. Montpellier, CNRS, INSERM, Montpellier, France
| | - Anaïs Biquet-Bisquert
- Centre de Biologie Structurale, Univ. Montpellier, CNRS, INSERM, Montpellier, France
| | - Manouk Abkarian
- Centre de Biologie Structurale, Univ. Montpellier, CNRS, INSERM, Montpellier, France
| | - Théo Pigaglio
- Aix Marseille Université, CNRS, Laboratoire de Chimie Bactérienne (UMR7283), IMM, IM2B, 13402, Marseille, France
| | - Farida Seduk
- Aix Marseille Université, CNRS, Laboratoire de Chimie Bactérienne (UMR7283), IMM, IM2B, 13402, Marseille, France
| | - Axel Magalon
- Aix Marseille Université, CNRS, Laboratoire de Chimie Bactérienne (UMR7283), IMM, IM2B, 13402, Marseille, France
| | - Francesco Pedaci
- Centre de Biologie Structurale, Univ. Montpellier, CNRS, INSERM, Montpellier, France.
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Zhang Y, Tan H, Yang S, Huang Y, Cai S, Jian J, Cai J, Qin Q. The role of dctP gene in regulating colonization, adhesion and pathogenicity of Vibrio alginolyticus strain HY9901. JOURNAL OF FISH DISEASES 2022; 45:421-434. [PMID: 34931326 DOI: 10.1111/jfd.13571] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Revised: 11/29/2021] [Accepted: 12/03/2021] [Indexed: 06/14/2023]
Abstract
Vibriosis caused by Vibrio alginolyticus has severely affected the development of mariculture industry in recent decades. DctP, a tripartite ATP-independent periplasmic transporter solute-binding subunit, is thought to be one of the virulence factors in Vibrio. In this study, the results displayed no difference in morphological characteristics and growth between ΔdctP (dctP mutant strain) and WT (wild-type strain). Nevertheless, the ability of swarming motility, biofilm formation, ECPase formation, cell adhesion and colonized ability of ΔdctP significantly decreased compared to those of WT. The LD50 of ΔdctP significantly increased by 40-fold compared to that of WT. The transcriptome analysis demonstrated the deletion mutation of dctP could regulate the expression levels of 22 genes related to colonization, adhesion and pathogenicity in V. alginolyticus. The analysis of qRT-PCR showed the transcriptome data were reliable. These results reveal the effect of attenuated function of DctP on colonization, adherence and pathogenicity by controlling the expression of related gene.
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Affiliation(s)
- Yilin Zhang
- Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animals & Key Laboratory of Control for Diseases of Aquatic Economic Animals of Guangdong Higher Education Institutes, Southern Marine Science and Engineering Guangdong Laboratory (Zhanjiang), Fisheries College of Guangdong Ocean University, Zhanjiang, China
| | - Huimin Tan
- Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animals & Key Laboratory of Control for Diseases of Aquatic Economic Animals of Guangdong Higher Education Institutes, Southern Marine Science and Engineering Guangdong Laboratory (Zhanjiang), Fisheries College of Guangdong Ocean University, Zhanjiang, China
| | - Shiping Yang
- Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animals & Key Laboratory of Control for Diseases of Aquatic Economic Animals of Guangdong Higher Education Institutes, Southern Marine Science and Engineering Guangdong Laboratory (Zhanjiang), Fisheries College of Guangdong Ocean University, Zhanjiang, China
| | - Yucong Huang
- Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animals & Key Laboratory of Control for Diseases of Aquatic Economic Animals of Guangdong Higher Education Institutes, Southern Marine Science and Engineering Guangdong Laboratory (Zhanjiang), Fisheries College of Guangdong Ocean University, Zhanjiang, China
| | - Shuanghu Cai
- Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animals & Key Laboratory of Control for Diseases of Aquatic Economic Animals of Guangdong Higher Education Institutes, Southern Marine Science and Engineering Guangdong Laboratory (Zhanjiang), Fisheries College of Guangdong Ocean University, Zhanjiang, China
- Guangdong Provincial Engineering Research Center for Aquatic Animal Health Assessment, Shenzhen Institute of Guangdong Ocean University, Shenzhen, China
| | - Jichang Jian
- Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animals & Key Laboratory of Control for Diseases of Aquatic Economic Animals of Guangdong Higher Education Institutes, Southern Marine Science and Engineering Guangdong Laboratory (Zhanjiang), Fisheries College of Guangdong Ocean University, Zhanjiang, China
- Guangdong Provincial Engineering Research Center for Aquatic Animal Health Assessment, Shenzhen Institute of Guangdong Ocean University, Shenzhen, China
| | - Jia Cai
- Guangdong Provincial Key Laboratory of Pathogenic Biology and Epidemiology for Aquatic Economic Animals & Key Laboratory of Control for Diseases of Aquatic Economic Animals of Guangdong Higher Education Institutes, Southern Marine Science and Engineering Guangdong Laboratory (Zhanjiang), Fisheries College of Guangdong Ocean University, Zhanjiang, China
- Guangdong Provincial Engineering Research Center for Aquatic Animal Health Assessment, Shenzhen Institute of Guangdong Ocean University, Shenzhen, China
| | - Qiwei Qin
- College of Marine Sciences, South China Agricultural University, Guangzhou, China
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Abstract
The bacterial flagellar motor is a complex macromolecular machine whose function and self-assembly present a fascinating puzzle for structural biologists. Here, we report that in diverse bacterial species, cell lysis leads to loss of the cytoplasmic switch complex and associated ATPase before other components of the motor. This loss may be prevented by the formation of a cytoplasmic vesicle around the complex. These observations suggest a relatively loose association of the switch complex with the rest of the flagellar machinery. IMPORTANCE We show in eight different bacterial species (belonging to different phyla) that the flagellar motor loses its cytoplasmic switch complex upon cell lysis, while the rest of the flagellum remains attached to the cell body. This suggests an evolutionary conserved weak interaction between the switch complex and the rest of the flagellum which is important to understand how the motor evolved. In addition, this information is crucial for mimicking such nanomachines in the laboratory.
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Mino T, Nishikino T, Iwatsuki H, Kojima S, Homma M. Effect of sodium ions on conformations of the cytoplasmic loop of the PomA stator protein of Vibrio alginolyticus. J Biochem 2019; 166:331-341. [PMID: 31147681 DOI: 10.1093/jb/mvz040] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2019] [Accepted: 05/24/2019] [Indexed: 01/13/2023] Open
Abstract
The sodium driven flagellar stator of Vibrio alginolyticus is a hetero-hexamer membrane complex composed of PomA and PomB, and acts as a sodium ion channel. The conformational change in the cytoplasmic region of PomA for the flagellar torque generation, which interacts directly with a rotor protein, FliG, remains a mystery. In this study, we introduced cysteine mutations into cytoplasmic charged residues of PomA, which are highly conserved and interact with FliG, to detect the conformational change by the reactivity of biotin maleimide. In vivo labelling experiments of the PomA mutants revealed that the accessibility of biotin maleimide at position of E96 was reduced with sodium ions. Such a reduction was also seen in the D24N and the plug deletion mutants of PomB, and the phenomenon was independent in the presence of FliG. This sodium ions specific reduction was also detected in Escherichia coli that produced PomA and PomB from a plasmid, but not in the purified stator complex. These results demonstrated that sodium ions cause a conformational change around the E96 residue of loop2-3 in the biological membrane.
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Affiliation(s)
- Taira Mino
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Furo-cyo, Nagoya, Japan
| | - Tatsuro Nishikino
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Furo-cyo, Nagoya, Japan
| | - Hiroto Iwatsuki
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Furo-cyo, Nagoya, Japan
| | - Seiji Kojima
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Furo-cyo, Nagoya, Japan
| | - Michio Homma
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Furo-cyo, Nagoya, Japan
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Rotational direction of flagellar motor from the conformation of FliG middle domain in marine Vibrio. Sci Rep 2018; 8:17793. [PMID: 30542147 PMCID: PMC6290876 DOI: 10.1038/s41598-018-35902-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Accepted: 11/08/2018] [Indexed: 12/14/2022] Open
Abstract
FliG, which is composed of three distinctive domains, N-terminal (N), middle (M), and C-terminal (C), is an essential rotor component that generates torque and determines rotational direction. To determine the role of FliG in determining flagellar rotational direction, we prepared rotational biased mutants of fliG in Vibrio alginolyticus. The E144D mutant, whose residue is belonging to the EHPQR-motif in FliGM, exhibited an increased number of switching events. This phenotype generated a response similar to the phenol-repellent response in chemotaxis. To clarify the effect of E144D mutation on the rotational switching, we combined the mutation with other che mutations (G214S, G215A and A282T) in FliG. Two of the double mutants suppressed the rotational biased phenotype. To gain structural insight into the mutations, we performed molecular dynamic simulations of the FliGMC domain, based on the crystal structure of Thermotoga maritima FliG and nuclear magnetic resonance analysis. Furthermore, we examined the swimming behavior of the fliG mutants lacking CheY. The results suggested that the conformation of FliG in E144D mutant was similar to that in the wild type. However, that of G214S and G215A caused a steric hindrance in FliG. The conformational change in FliGM triggered by binding CheY may lead to a rapid change of direction and may occur in both directional states.
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Abstract
Most bacteria can swim by rotating the flagellum. The basal body of the flagellum is an essential part for this motor function. Recent comprehensive analysis of the flagellar basal body structures across bacteria by cryo-electron tomography has revealed that they all share core structures, the rod, and rings: the C ring, M ring, S ring, L ring, and P ring. Furthermore, it also has uncovered that in some bacteria, there are extra ring structures in the periplasmic space and outer-membrane. Here, we describe a protocol to isolate the basal body of the flagellar basal body from a marine bacterium, Vibrio alginolyticus, for structural analysis of additional ring structures, the T ring and H ring.
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Park Y, Kim Y, Ko W, Lim S. Instabilities of a rotating helical rod in a viscous fluid. Phys Rev E 2017; 95:022410. [PMID: 28297972 DOI: 10.1103/physreve.95.022410] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2016] [Indexed: 06/06/2023]
Abstract
Bacteria such as Vibrio alginolyticus swim through a fluid by utilizing the rotational motion of their helical flagellum driven by a rotary motor. The flagellar motor is embedded in the cell body and turns either clockwise (CW) or counterclockwise (CCW), which may lead to straight forward or backward swimming, or reorientation of the cell. In this paper we investigate the dynamics of the helical flagellum by adopting the Kirchhoff rod theory in which the flagellum is described as a space curve associated with orthonormal triads that measure the degree of bending and twisting of the rod. The hydrodynamic interaction with the flagellum is described by the regularized Stokes formulation. We focus on two different types of instabilities: (1) whirling instability of a rotating helical filament in the absence of a hook and (2) buckling instability of a flagellum in the presence of a compliant hook that links the flagellar filament to the rotary motor. Our simulation results show that the helical filament without a hook displays three regimes of dynamical motions: stable twirling, unstable whirling, and stable overwhirling motions depending on the physical parameters, such as rotational frequency and elastic properties of the flagellum. The helical filament with a hook experiences buckling instability when the motor switches the direction of rotation and the elastic properties of the hook change. Variations of physical parameter values of the hook such as the bending modulus and the length make an impact on the buckling angle, which may subsequently affect the reorientation of the cell.
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Affiliation(s)
- Yunyoung Park
- Department of Mathematics, Chung-Ang University, Dongjakgu, Heukseokdong, Seoul 156-756, Republic of Korea
| | - Yongsam Kim
- Department of Mathematics, Chung-Ang University, Dongjakgu, Heukseokdong, Seoul 156-756, Republic of Korea
| | - William Ko
- Department of Mathematical Sciences, University of Cincinnati, 4199 French Hall West, Cincinnati, Ohio 45221, USA
| | - Sookkyung Lim
- Department of Mathematical Sciences, University of Cincinnati, 4199 French Hall West, Cincinnati, Ohio 45221, USA
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9
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Onoue Y, Kojima S, Homma M. Effect of FliG three amino acids deletion in Vibrio polar-flagellar rotation and formation. J Biochem 2015; 158:523-9. [PMID: 26142283 DOI: 10.1093/jb/mvv068] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Accepted: 06/03/2015] [Indexed: 11/14/2022] Open
Abstract
Most of bacteria can swim by rotating flagella bidirectionally. The C ring, located at the bottom of the flagellum and in the cytoplasmic space, consists of FliG, FliM and FliN, and has an important function in flagellar protein secretion, torque generation and rotational switch of the motor. FliG is the most important part of the C ring that interacts directly with a stator subunit. Here, we introduced a three-amino acids in-frame deletion mutation (ΔPSA) into FliG from Vibrio alginolyticus, whose corresponding mutation in Salmonella confers a switch-locked phenotype, and examined its phenotype. We found that this FliG mutant could not produce flagellar filaments in a fliG null strain but the FliG(ΔPSA) protein could localize at the cell pole as does the wild-type protein. Unexpectedly, when this mutant was expressed in a wild-type strain, cells formed flagella efficiently but the motor could not rotate. We propose that this different phenotype in Vibrio and Salmonella might be due to distinct interactions between FliG mutant and FliM in the C ring between the bacterial species.
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Affiliation(s)
- Yasuhiro Onoue
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan
| | - Seiji Kojima
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan
| | - Michio Homma
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan
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González Y, Camarena L, Dreyfus G. Induction of the lateral flagellar system of Vibrio shilonii is an early event after inhibition of the sodium ion flux in the polar flagellum. Can J Microbiol 2015; 61:183-91. [DOI: 10.1139/cjm-2014-0579] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In this study, we show the induction of lateral flagella by the action of the sodium channel blocker phenamil, in the marine bacterium Vibrio shilonii, a coral pathogen that causes bleaching. We analyzed the growth and morphology of cells treated with phenamil. A time course analysis showed that after 30 min of exposure to the sodium channel blocker, lateral flagella were present and could be detected by electron microscopy. Detection of the mRNA of the master regulator (lafK) and lateral flagellin (lafA) by RT–PCR confirmed the expression of lateral flagellar genes. We show the simultaneous isolation of polar and, for the first time, lateral flagellar hook-basal bodies. This allowed us to compare the dimensions and morphological characteristics of the 2 structures.
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Affiliation(s)
- Yael González
- Instituto de Fisiología Celular, Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México. Ap. Postal 70-243, Cd. Universitaria, México DF 04510, Mexico
| | - Laura Camarena
- Instituto de Investigaciones Biomédicas, Departamento de Biología Molecular y Biotecnología, Universidad Nacional Autónoma de México, México DF, Mexico
| | - Georges Dreyfus
- Instituto de Fisiología Celular, Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México. Ap. Postal 70-243, Cd. Universitaria, México DF 04510, Mexico
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Contribution of many charged residues at the stator-rotor interface of the Na+-driven flagellar motor to torque generation in Vibrio alginolyticus. J Bacteriol 2014; 196:1377-85. [PMID: 24464458 DOI: 10.1128/jb.01392-13] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
In torque generation by the bacterial flagellar motor, it has been suggested that electrostatic interactions between charged residues of MotA and FliG at the rotor-stator interface are important. However, the actual role(s) of those charged residues has not yet been clarified. In this study, we systematically made mutants of Vibrio alginolyticus whose charged residues of PomA (MotA homologue) and FliG were replaced by uncharged or charge-reversed residues and characterized the motilities of those mutants. We found that the members of a group of charged residues, 7 in PomA and 6 in FliG, collectively participate in torque generation of the Na(+)-driven flagellar motor in Vibrio. An additional specific interaction between PomA-E97 and FliG-K284 is critical for proper performance of the Vibrio motor. Our results also reveal that more charged residues are involved in the PomA-FliG interactions in the Vibrio Na(+)-driven motor than in the MotA-FliG interactions in the H(+)-driven one. This suggests that a larger number of conserved charged residues at the PomA-FliG interface contributes to the robustness of the Vibrio motor against mutations. The interaction surfaces of the stator and rotor of the Na(+)-driven motor seem to be more complex than those previously proposed in the H(+)-driven motor.
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12
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Gohara M, Kobayashi S, Abe-Yoshizumi R, Nonoyama N, Kojima S, Asami Y, Homma M. Biophysical characterization of the C-terminal region of FliG, an essential rotor component of the Na+-driven flagellar motor. J Biochem 2013; 155:83-9. [DOI: 10.1093/jb/mvt100] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
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13
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Kojima S, Nonoyama N, Takekawa N, Fukuoka H, Homma M. Mutations targeting the C-terminal domain of FliG can disrupt motor assembly in the Na(+)-driven flagella of Vibrio alginolyticus. J Mol Biol 2011; 414:62-74. [PMID: 21986199 DOI: 10.1016/j.jmb.2011.09.019] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2011] [Revised: 09/10/2011] [Accepted: 09/13/2011] [Indexed: 10/17/2022]
Abstract
The torque of the bacterial flagellar motor is generated by the rotor-stator interaction coupled with specific ion translocation through the stator channel. To produce a fully functional motor, multiple stator units must be properly incorporated around the rotor by an as yet unknown mechanism to engage the rotor-stator interactions. Here, we investigated stator assembly using a mutational approach of the Na(+)-driven polar flagellar motor of Vibrio alginolyticus, whose stator is localized at the flagellated cell pole. We mutated a rotor protein, FliG, which is located at the C ring of the basal body and closely participates in torque generation, and found that point mutation L259Q, L270R or L271P completely abolishes both motility and polar localization of the stator without affecting flagellation. Likewise, mutations V274E and L279P severely affected motility and stator assembly. Those residues are localized at the core of the globular C-terminal domain of FliG when mapped onto the crystal structure of FliG from Thermotoga maritima, which suggests that those mutations induce quite large structural alterations at the interface responsible for the rotor-stator interaction. These results show that the C-terminal domain of FliG is critical for the proper assembly of PomA/PomB stator complexes around the rotor and probably functions as the target of the stator at the rotor side.
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Affiliation(s)
- Seiji Kojima
- Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8602, Japan.
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14
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Koike M, Nishioka N, Kojima S, Homma M. Characterization of the flagellar motor composed of functional GFP-fusion derivatives of FliG in the Na +-driven polar flagellum of Vibrio alginolyticus. Biophysics (Nagoya-shi) 2011; 7:59-67. [PMID: 27857593 PMCID: PMC5036772 DOI: 10.2142/biophysics.7.59] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Accepted: 08/18/2011] [Indexed: 12/01/2022] Open
Abstract
The polar flagellum of Vibrio alginolyticus is driven by sodium ion flux via a stator complex, composed of PomA and PomB, across the cell membrane. The interaction between PomA and the rotor component FliG is believed to generate torque required for flagellar rotation. Previous research reported that a GFP-fused FliG retained function in the Vibrio flagellar motor. In this study, we found that N-terminal or C-terminal fusion of GFP has different effects on both torque generation and the switching frequency of the direction of flagellar motor rotation. We could detect the GFP-fused FliG in the basal-body (rotor) fraction although its association with the basal body was less stable than that of intact FliG. Furthermore, the fusion of GFP to the C-terminus of FliG, which is believed to be directly involved in torque generation, resulted in very slow motility and prohibited the directional change of motor rotation. On the other hand, the fusion of GFP to the N-terminus of FliG conferred almost the same swimming speed as intact FliG. These results are consistent with the premise that the C-terminal domain of FliG is directly involved in torque generation and the GFP fusions are useful to analyze the functions of various domains of FliG.
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Affiliation(s)
- Masafumi Koike
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-Ku, Nagoya 464-8602, Japan
| | - Noriko Nishioka
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-Ku, Nagoya 464-8602, Japan
| | - Seiji Kojima
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-Ku, Nagoya 464-8602, Japan
| | - Michio Homma
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-Ku, Nagoya 464-8602, Japan
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15
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Abstract
The Na(+) -driven bacterial flagellar motor is a molecular machine powered by an electrochemical potential gradient of sodium ions across the cytoplasmic membrane. The marine bacterium Vibrio alginolyticus has a single polar flagellum that enables it to swim in liquid. The flagellar motor contains a basal body and a stator complexes, which are composed of several proteins. PomA, PomB, MotX, and MotY are thought to be essential components of the stator that are required to generate the torque of the rotation. Several mutations have been investigated to understand the characteristics and function of the ion channel in the stator and the mechanism of its assembly around the rotor to complete the motor. In this review, we summarize recent results of the Na(+) -driven motor in the polar flagellum of Vibrio.
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Affiliation(s)
- Na Li
- Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Japan
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16
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Fukuoka H, Inoue Y, Terasawa S, Takahashi H, Ishijima A. Exchange of rotor components in functioning bacterial flagellar motor. Biochem Biophys Res Commun 2010; 394:130-5. [DOI: 10.1016/j.bbrc.2010.02.129] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2010] [Accepted: 02/19/2010] [Indexed: 12/27/2022]
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