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Partridge JD, Harshey RM. Flagellar protein FliL: A many-splendored thing. Mol Microbiol 2024. [PMID: 39096095 DOI: 10.1111/mmi.15301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2024] [Revised: 07/09/2024] [Accepted: 07/16/2024] [Indexed: 08/04/2024]
Abstract
FliL is a bacterial flagellar protein demonstrated to associate with, and regulate ion flow through, the stator complex in a diverse array of bacterial species. FliL is also implicated in additional functions such as stabilizing the flagellar rod, modulating rotor bias, sensing the surface, and regulating gene expression. How can one protein do so many things? Its location is paramount to understanding its numerous functions. This review will look at the evidence, attempt to resolve some conflicting findings, and offer new thoughts on FliL.
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Affiliation(s)
- Jonathan D Partridge
- Department of Molecular Biosciences and the LaMontagne Center for Infectious Diseases, The University of Texas at Austin, Austin, Texas, USA
| | - Rasika M Harshey
- Department of Molecular Biosciences and the LaMontagne Center for Infectious Diseases, The University of Texas at Austin, Austin, Texas, USA
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2
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Miyamura Y, Nishikino T, Koiwa H, Homma M, Kojima S. Roles of linker region flanked by transmembrane and peptidoglycan binding region of PomB in energy conversion of the Vibrio flagellar motor. Genes Cells 2024; 29:282-289. [PMID: 38351850 DOI: 10.1111/gtc.13102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2023] [Revised: 01/26/2024] [Accepted: 01/28/2024] [Indexed: 04/04/2024]
Abstract
The flagellar components of Vibrio spp., PomA and PomB, form a complex that transduces sodium ion and contributes to rotate flagella. The transmembrane protein PomB is attached to the basal body T-ring by its periplasmic region and has a plug segment following the transmembrane helix to prevent ion flux. Previously we showed that PomB deleted from E41 to R120 (Δ41-120) was functionally comparable to the full-length PomB. In this study, three deletions after the plug region, PomB (Δ61-120), PomB (Δ61-140), and PomB (Δ71-150), were generated. PomB (Δ61-120) conferred motility, whereas the other two mutants showed almost no motility in soft agar plate; however, we observed some swimming cells with speed comparable for the wild-type cells. When the two PomB mutants were introduced into a wild-type strain, the swimming ability was not affected by the mutant PomBs. Then, we purified the mutant PomAB complexes to confirm the stator formation. When plug mutations were introduced into the PomB mutants, the reduced motility by the deletion was rescued, suggesting that the stator was activated. Our results indicate that the deletions prevent the stator activation and the linker and plug regions, from E41 to S150, are not essential for the motor function of PomB but are important for its regulation.
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Affiliation(s)
- Yusuke Miyamura
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Japan
| | - Tatsuro Nishikino
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Nagoya, Japan
| | - Hiroaki Koiwa
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Japan
| | - Michio Homma
- Division of Material Science and Biological Science, Graduate School of Science, Nagoya University, Nagoya, Japan
| | - Seiji Kojima
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Japan
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3
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Sathiyamoorthi E, Lee JH, Tan Y, Lee J. Antimicrobial and antibiofilm activities of formylchromones against Vibrio parahaemolyticus and Vibrio harveyi. Front Cell Infect Microbiol 2023; 13:1234668. [PMID: 37662002 PMCID: PMC10471482 DOI: 10.3389/fcimb.2023.1234668] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Accepted: 07/28/2023] [Indexed: 09/05/2023] Open
Abstract
Gram-negative Vibrio species are major foodborne pathogens often associated with seafood intake that causes gastroenteritis. On food surfaces, biofilm formation by Vibrio species enhances the resistance of bacteria to disinfectants and antimicrobial agents. Hence, an efficient antibacterial and antibiofilm approach is urgently required. This study examined the antibacterial and antivirulence effects of chromones and their 26 derivatives against V. parahaemolyticus and V. harveyi. 6-Bromo-3-formylchromone (6B3FC) and 6-chloro-3-formylchromone (6C3FC) were active antibacterial and antibiofilm compounds. Both 6B3FC and 6C3FC exhibited minimum inhibitory concentrations (MICs) of 20 µg/mL for planktonic cell growth and dose-dependently inhibited biofilm formation. Additionally, they decreased swimming motility, protease activity, fimbrial agglutination, hydrophobicity, and indole production at 20 µg/mL which impaired the growth of the bacteria. Furthermore, the active compounds could completely inhibit the slimy substances and microbial cells on the surface of the squid and shrimp. The most active compound 6B3FC inhibited the gene expression associated in quorum sensing and biofilm formation (luxS, opaR), pathogenicity (tdh), and membrane integrity (vmrA) in V. parahaemolyticus. However, toxicity profiling using seed germination and Caenorhabditis elegans models suggests that 6C3FC may have moderate effect at 50 µg/mL while 6B3FC was toxic to the nematodes 20-100 µg/mL. These findings suggest chromone analogs, particularly two halogenated formylchromones (6B3FC and 6C3FC), were effective antimicrobial and antibiofilm agents against V. parahaemolyticus in the food and pharmaceutical sectors.
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Affiliation(s)
| | - Jin-Hyung Lee
- School of Chemical Engineering, Yeungnam University, Gyeongsan, Republic of Korea
| | - Yulong Tan
- Special Food Research Institute, Qingdao Agricultural University, Qingdao, China
| | - Jintae Lee
- School of Chemical Engineering, Yeungnam University, Gyeongsan, Republic of Korea
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Hu H, Popp PF, Santiveri M, Roa-Eguiara A, Yan Y, Martin FJO, Liu Z, Wadhwa N, Wang Y, Erhardt M, Taylor NMI. Ion selectivity and rotor coupling of the Vibrio flagellar sodium-driven stator unit. Nat Commun 2023; 14:4411. [PMID: 37500658 PMCID: PMC10374538 DOI: 10.1038/s41467-023-39899-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2023] [Accepted: 07/04/2023] [Indexed: 07/29/2023] Open
Abstract
Bacteria swim using a flagellar motor that is powered by stator units. Vibrio spp. are highly motile bacteria responsible for various human diseases, the polar flagella of which are exclusively driven by sodium-dependent stator units (PomAB). However, how ion selectivity is attained, how ion transport triggers the directional rotation of the stator unit, and how the stator unit is incorporated into the flagellar rotor remained largely unclear. Here, we have determined by cryo-electron microscopy the structure of Vibrio PomAB. The electrostatic potential map uncovers sodium binding sites, which together with functional experiments and molecular dynamics simulations, reveal a mechanism for ion translocation and selectivity. Bulky hydrophobic residues from PomA prime PomA for clockwise rotation. We propose that a dynamic helical motif in PomA regulates the distance between PomA subunit cytoplasmic domains, stator unit activation, and torque transmission. Together, our study provides mechanistic insights for understanding ion selectivity and rotor incorporation of the stator unit of the bacterial flagellum.
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Affiliation(s)
- Haidai Hu
- Structural Biology of Molecular Machines Group, Protein Structure & Function Program, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200, Copenhagen, Denmark
| | - Philipp F Popp
- Institute for Biology/Molecular Microbiology, Humboldt-Universität zu Berlin, Philippstr. 13, 10115, Berlin, Germany
| | - Mònica Santiveri
- Structural Biology of Molecular Machines Group, Protein Structure & Function Program, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200, Copenhagen, Denmark
| | - Aritz Roa-Eguiara
- Structural Biology of Molecular Machines Group, Protein Structure & Function Program, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200, Copenhagen, Denmark
| | - Yumeng Yan
- Structural Biology of Molecular Machines Group, Protein Structure & Function Program, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200, Copenhagen, Denmark
| | - Freddie J O Martin
- Structural Biology of Molecular Machines Group, Protein Structure & Function Program, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200, Copenhagen, Denmark
| | - Zheyi Liu
- College of Life Sciences, Zhejiang University, Hangzhou, 310027, China
- The Provincial International Science and Technology Cooperation Base on Engineering Biology, International Campus of Zhejiang University, Haining, 314400, China
| | - Navish Wadhwa
- Department of Physics, Arizona State University, Tempe, AZ, 85287, USA
- Biodesign Center for Mechanisms of Evolution, Arizona State University, Tempe, AZ, 85287, USA
| | - Yong Wang
- College of Life Sciences, Zhejiang University, Hangzhou, 310027, China
- The Provincial International Science and Technology Cooperation Base on Engineering Biology, International Campus of Zhejiang University, Haining, 314400, China
| | - Marc Erhardt
- Institute for Biology/Molecular Microbiology, Humboldt-Universität zu Berlin, Philippstr. 13, 10115, Berlin, Germany
- Max Planck Unit for the Science of Pathogens, Berlin, Germany
| | - Nicholas M I Taylor
- Structural Biology of Molecular Machines Group, Protein Structure & Function Program, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200, Copenhagen, Denmark.
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Terashima H, Homma M, Kojima S. Site-Directed Cross-Linking Between Bacterial Flagellar Motor Proteins In Vivo. Methods Mol Biol 2023; 2646:71-82. [PMID: 36842107 DOI: 10.1007/978-1-0716-3060-0_7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/27/2023]
Abstract
The bacterial flagellum employs a rotary motor embedded on the cell surface. The motor consists of the stator and rotor elements and is driven by ion influx (typically H+ or Na+) through an ion channel of the stator. Ion influx induces conformational changes in the stator, followed by changes in the interactions between the stator and rotor. The driving force to rotate the flagellum is thought to be generated by changing the stator-rotor interactions. In this chapter, we describe two methods for investigating the interactions between the stator and rotor: site-directed in vivo photo-crosslinking and site-directed in vivo cysteine disulfide crosslinking.
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Affiliation(s)
- Hiroyuki Terashima
- Department of Bacteriology, Institute of Tropical Medicine (NEKKEN), Nagasaki University, Nagasaki, Japan.
| | - Michio Homma
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Japan
| | - Seiji Kojima
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Japan
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6
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Kojima S, Homma M, Kandori H. Purification of the Na +-Driven PomAB Stator Complex and Its Analysis Using ATR-FTIR Spectroscopy. Methods Mol Biol 2023; 2646:95-107. [PMID: 36842109 DOI: 10.1007/978-1-0716-3060-0_9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/27/2023]
Abstract
The flagellar motor of marine Vibrio is driven by the sodium-motive force across the inner membrane. The stator complex, consisting of two membrane proteins PomA and PomB, is responsible for energy conversion in the motor. To understand the coupling of the Na+ flux with torque generation, it is essential to clearly identify the Na+-binding sites and the Na+ flux pathway through the stator channel. Although residues essential for Na+ flux have been identified by using mutational analysis, it has been difficult to observe Na+ binding to the PomAB stator complex. Here we describe a method to monitor the binding of Na+ to purified PomAB stator complex using attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy. This method demonstrates that Na+-binding sites are formed by critical aspartic acid and threonine residues located in the transmembrane segments of PomAB.
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Affiliation(s)
- Seiji Kojima
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Japan.
| | - Michio Homma
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Japan
| | - Hideki Kandori
- Department of Life Science and Applied Chemistry, Nagoya Institute of Technology, Nagoya, Japan.
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Huang Y, Chen J, Jiang Q, Huang N, Ding X, Peng L, Deng X. The molybdate-binding protein ModA is required for Proteus mirabilis-induced UTI. Front Microbiol 2023; 14:1156273. [PMID: 37180242 PMCID: PMC10174112 DOI: 10.3389/fmicb.2023.1156273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Accepted: 03/28/2023] [Indexed: 05/16/2023] Open
Abstract
Background Proteus mirabilis is one of the pathogens commonly causing urinary tract infections (UTIs). The molybdate-binding protein ModA encoded by modA binds molybdate with high affinity and transports it. Increasing evidence shows that ModA promotes the survival of bacteria in anaerobic environments and participates in bacterial virulence by obtaining molybdenum. However, the role of ModA in the pathogenesis of P. mirabilis remains unknown. Results In this study, a series of phenotypic assays and transcriptomic analyses were used to study the role of ModA in the UTIs induced by P. mirabilis. Our data showed that ModA absorbed molybdate with high affinity and incorporated it into molybdopterin, thus affecting the anaerobic growth of P. mirabilis. Loss of ModA enhanced bacterial swarming and swimming and up-regulated the expression of multiple genes in flagellar assembly pathway. The loss of ModA also resulted in decreased biofilm formation under anaerobic growth conditions. The modA mutant significantly inhibited bacterial adhesion and invasion to urinary tract epithelial cells and down-regulated the expression of multiple genes associated with pilus assembly. Those alterations were not due to anaerobic growth defects. In addition, the decreased bacteria in the bladder tissue, the weakened inflammatory damage, the low level of IL-6, and minor weight change was observed in the UTI mouse model infected with modA mutant. Conclusion Here, we reported that in P. mirabilis, ModA mediated the transport of molybdate, thereby affecting the activity of nitrate reductase and thus affecting the growth of bacteria under anaerobic conditions. Overall, this study clarified the indirect role of ModA in the anaerobic growth, motility, biofilm formation, and pathogenicity of P. mirabilis and its possible pathway, and emphasized the importance of the molybdate-binding protein ModA to P. mirabilis in mediating molybdate uptake, allowing the bacterium to adapt to complex environmental conditions and cause UTIs. Our results provided valuable information on the pathogenesis of ModA-induced P. mirabilis UTIs and may facilitate the development of new treatment strategies.
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Affiliation(s)
- Yi Huang
- Guangzhou Key Laboratory for Clinical Rapid Diagnosis and Early Warning of Infectious Diseases, Guangzhou Medical University, Guangzhou, Guangdong, China
- KingMed School of Laboratory Medicine, Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Jinbin Chen
- Guangzhou Key Laboratory for Clinical Rapid Diagnosis and Early Warning of Infectious Diseases, Guangzhou Medical University, Guangzhou, Guangdong, China
- KingMed School of Laboratory Medicine, Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Qiao Jiang
- Guangdong 999 Brain Hospital, Guangzhou, Guangdong, China
| | - Nan Huang
- Guangzhou Key Laboratory for Clinical Rapid Diagnosis and Early Warning of Infectious Diseases, Guangzhou Medical University, Guangzhou, Guangdong, China
- KingMed School of Laboratory Medicine, Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Xin Ding
- Guangzhou Key Laboratory for Clinical Rapid Diagnosis and Early Warning of Infectious Diseases, Guangzhou Medical University, Guangzhou, Guangdong, China
- KingMed School of Laboratory Medicine, Guangzhou Medical University, Guangzhou, Guangdong, China
| | - Liang Peng
- KingMed School of Laboratory Medicine, Guangzhou Medical University, Guangzhou, Guangdong, China
- The Fifth Affiliated Hospital of Guangzhou Medical University, Guangzhou, Guangdong, China
- *Correspondence: Xiaoyan Deng, ; Liang Peng,
| | - Xiaoyan Deng
- Guangzhou Key Laboratory for Clinical Rapid Diagnosis and Early Warning of Infectious Diseases, Guangzhou Medical University, Guangzhou, Guangdong, China
- KingMed School of Laboratory Medicine, Guangzhou Medical University, Guangzhou, Guangdong, China
- *Correspondence: Xiaoyan Deng, ; Liang Peng,
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8
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Ridone P, Ishida T, Lin A, Humphreys DT, Giannoulatou E, Sowa Y, Baker MAB. The rapid evolution of flagellar ion selectivity in experimental populations of E. coli. SCIENCE ADVANCES 2022; 8:eabq2492. [PMID: 36417540 PMCID: PMC9683732 DOI: 10.1126/sciadv.abq2492] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/27/2022] [Accepted: 10/06/2022] [Indexed: 06/16/2023]
Abstract
Determining which cellular processes facilitate adaptation requires a tractable experimental model where an environmental cue can generate variants that rescue function. The bacterial flagellar motor (BFM) is an excellent candidate-an ancient and highly conserved molecular complex for bacterial propulsion toward favorable environments. Motor rotation is often powered by H+ or Na+ ion transit through the torque-generating stator subunit of the motor complex, and ion selectivity has adapted over evolutionary time scales. Here, we used CRISPR engineering to replace the native Escherichia coli H+-powered stator with Na+-powered stator genes and report the spontaneous reversion of our edit in a low-sodium environment. We followed the evolution of the stators during their reversion to H+-powered motility and used both whole-genome and RNA sequencing to identify genes involved in the cell's adaptation. Our transplant of an unfit protein and the cells' rapid response to this edit demonstrate the adaptability of the stator subunit and highlight the hierarchical modularity of the flagellar motor.
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Affiliation(s)
- Pietro Ridone
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, Australia
| | - Tsubasa Ishida
- Department of Frontier Bioscience, Hosei University, Tokyo, Japan
- Research Center for Micro-Nano Technology, Hosei University, Tokyo, Japan
| | - Angela Lin
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, Australia
| | - David T. Humphreys
- Victor Chang Cardiac Research Institute, Sydney, Australia
- School of Clinical Medicine, Faculty of Medicine and Health, UNSW Sydney, Australia
| | | | - Yoshiyuki Sowa
- Department of Frontier Bioscience, Hosei University, Tokyo, Japan
- Research Center for Micro-Nano Technology, Hosei University, Tokyo, Japan
| | - Matthew A. B. Baker
- School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney, Australia
- ARC Centre of Excellence in Synthetic Biology, University of New South Wales, Sydney, Australia
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Lu H, Sun Y, Wang X, Lu Z, Zhu J. Transcriptomics reveal the antibiofilm mechanism of NaCl combined with citral against Vibrio parahaemolyticus. Appl Microbiol Biotechnol 2022; 107:313-326. [DOI: 10.1007/s00253-022-12286-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Revised: 11/05/2022] [Accepted: 11/08/2022] [Indexed: 11/24/2022]
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Homma M, Takekawa N, Fujiwara K, Hao Y, Onoue Y, Kojima S. Formation of multiple flagella caused by a mutation of the flagellar rotor protein FliM in Vibrio alginolyticus. Genes Cells 2022; 27:568-578. [PMID: 35842835 DOI: 10.1111/gtc.12975] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Revised: 06/21/2022] [Accepted: 07/11/2022] [Indexed: 11/30/2022]
Abstract
Marine bacterium Vibrio alginolyticus forms a single flagellum at a cell pole. In Vibrio, two proteins (GTPase FlhF and ATPase FlhG) regulate the number of flagella. We previously isolated the NMB155 mutant that forms multiple flagella despite the absence of mutations in flhF and flhG. Whole-genome sequencing of NMB155 identified an E9K mutation in FliM that is a component of C-ring in the flagellar rotor. Mutations in FliM result in defects in flagellar formation (fla) and flagellar rotation (che or mot); however, there are a few reports indicating that FliM mutations increase the number of flagella. Here, we determined that the E9K mutation confers the multi-flagellar phenotype and also the che phenotype. The co-expression of wild-type FliM and FliM-E9K indicated that they were competitive in regard to determining the flagellar number. The ATPase activity of FlhG has been correlated with the number of flagella. We observed that the ATPase activity of FlhG was increased by the addition of FliM but not by the addition of FliM-E9K in vitro. This indicates that FliM interacts with FlhG to increase its ATPase activity, and the E9K mutation may inhibit this interaction. FliM may control the ATPase activity of FlhG to properly regulate the number of the polar flagellum at the cell pole. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Michio Homma
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Aichi, Japan
| | - Norihiro Takekawa
- Department of Macromolecular Science, Graduate School of Science, Osaka University, Osaka, Japan
| | - Kazushi Fujiwara
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Aichi, Japan
| | - Yuxi Hao
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Aichi, Japan
| | - Yasuhiro Onoue
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Aichi, Japan
| | - Seiji Kojima
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Aichi, Japan
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11
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Wei Y, Wang J, Wu S, Zhou R, Zhang K, Zhang Z, Liu J, Qin S, Shi J. Nanomaterial-Based Zinc Ion Interference Therapy to Combat Bacterial Infections. Front Immunol 2022; 13:899992. [PMID: 35844505 PMCID: PMC9279624 DOI: 10.3389/fimmu.2022.899992] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2022] [Accepted: 05/27/2022] [Indexed: 01/04/2023] Open
Abstract
Pathogenic bacterial infections are the second highest cause of death worldwide and bring severe challenges to public healthcare. Antibiotic resistance makes it urgent to explore new antibacterial therapy. As an essential metal element in both humans and bacteria, zinc ions have various physiological and biochemical functions. They can stabilize the folded conformation of metalloproteins and participate in critical biochemical reactions, including DNA replication, transcription, translation, and signal transduction. Therefore, zinc deficiency would impair bacterial activity and inhibit the growth of bacteria. Interestingly, excess zinc ions also could cause oxidative stress to damage DNA, proteins, and lipids by inhibiting the function of respiratory enzymes to promote the formation of free radicals. Such dual characteristics endow zinc ions with unparalleled advantages in the direction of antibacterial therapy. Based on the fascinating features of zinc ions, nanomaterial-based zinc ion interference therapy emerges relying on the outstanding benefits of nanomaterials. Zinc ion interference therapy is divided into two classes: zinc overloading and zinc deprivation. In this review, we summarized the recent innovative zinc ion interference strategy for the treatment of bacterial infections and focused on analyzing the antibacterial mechanism of zinc overloading and zinc deprivation. Finally, we discuss the current limitations of zinc ion interference antibacterial therapy and put forward problems of clinical translation for zinc ion interference antibacterial therapy.
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Affiliation(s)
- Yongbin Wei
- School of Pharmaceutical Sciences, Zhengzhou University, Zhengzhou, China
| | - Jiaming Wang
- School of Pharmaceutical Sciences, Zhengzhou University, Zhengzhou, China
| | - Sixuan Wu
- School of Pharmaceutical Sciences, Zhengzhou University, Zhengzhou, China
| | - Ruixue Zhou
- School of Pharmaceutical Sciences, Zhengzhou University, Zhengzhou, China
| | - Kaixiang Zhang
- School of Pharmaceutical Sciences, Zhengzhou University, Zhengzhou, China
- Key Laboratory of Targeting Therapy and Diagnosis for Critical Diseases, Zhengzhou University, Zhengzhou, China
- Key Laboratory of Key Drug Preparation Technology Ministry of Education, Zhengzhou University, Zhengzhou, China
| | - Zhenzhong Zhang
- School of Pharmaceutical Sciences, Zhengzhou University, Zhengzhou, China
- Key Laboratory of Targeting Therapy and Diagnosis for Critical Diseases, Zhengzhou University, Zhengzhou, China
- Key Laboratory of Key Drug Preparation Technology Ministry of Education, Zhengzhou University, Zhengzhou, China
| | - Junjie Liu
- School of Pharmaceutical Sciences, Zhengzhou University, Zhengzhou, China
- Key Laboratory of Targeting Therapy and Diagnosis for Critical Diseases, Zhengzhou University, Zhengzhou, China
- Key Laboratory of Key Drug Preparation Technology Ministry of Education, Zhengzhou University, Zhengzhou, China
- *Correspondence: Junjie Liu, ; Shangshang Qin, ; Jinjin Shi,
| | - Shangshang Qin
- School of Pharmaceutical Sciences, Zhengzhou University, Zhengzhou, China
- Key Laboratory of Targeting Therapy and Diagnosis for Critical Diseases, Zhengzhou University, Zhengzhou, China
- Key Laboratory of Key Drug Preparation Technology Ministry of Education, Zhengzhou University, Zhengzhou, China
- *Correspondence: Junjie Liu, ; Shangshang Qin, ; Jinjin Shi,
| | - Jinjin Shi
- School of Pharmaceutical Sciences, Zhengzhou University, Zhengzhou, China
- Key Laboratory of Targeting Therapy and Diagnosis for Critical Diseases, Zhengzhou University, Zhengzhou, China
- Key Laboratory of Key Drug Preparation Technology Ministry of Education, Zhengzhou University, Zhengzhou, China
- *Correspondence: Junjie Liu, ; Shangshang Qin, ; Jinjin Shi,
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Guo S, Liu J. The Bacterial Flagellar Motor: Insights Into Torque Generation, Rotational Switching, and Mechanosensing. Front Microbiol 2022; 13:911114. [PMID: 35711788 PMCID: PMC9195833 DOI: 10.3389/fmicb.2022.911114] [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: 04/02/2022] [Accepted: 05/06/2022] [Indexed: 11/18/2022] Open
Abstract
The flagellar motor is a bidirectional rotary nanomachine used by many bacteria to sense and move through environments of varying complexity. The bidirectional rotation of the motor is governed by interactions between the inner membrane-associated stator units and the C-ring in the cytoplasm. In this review, we take a structural biology perspective to discuss the distinct conformations of the stator complex and the C-ring that regulate bacterial motility by switching rotational direction between the clockwise (CW) and counterclockwise (CCW) senses. We further contextualize recent in situ structural insights into the modulation of the stator units by accessory proteins, such as FliL, to generate full torque. The dynamic structural remodeling of the C-ring and stator complexes as well as their association with signaling and accessory molecules provide a mechanistic basis for how bacteria adjust motility to sense, move through, and survive in specific niches both outside and within host cells and tissues.
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Affiliation(s)
- Shuaiqi Guo
- Microbial Sciences Institute, Yale University, West Haven, CT, United States.,Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, CT, United States
| | - Jun Liu
- Microbial Sciences Institute, Yale University, West Haven, CT, United States.,Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, CT, United States
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13
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Homma M, Kojima S. The Periplasmic Domain of the Ion-Conducting Stator of Bacterial Flagella Regulates Force Generation. Front Microbiol 2022; 13:869187. [PMID: 35572622 PMCID: PMC9093738 DOI: 10.3389/fmicb.2022.869187] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Accepted: 03/24/2022] [Indexed: 11/23/2022] Open
Abstract
The bacterial flagellar stator is a unique ion-conducting membrane protein complex composed of two kinds of proteins, the A subunit and the B subunit. The stator couples the ion-motive force across the membrane into rotational force. The stator becomes active only when it is incorporated into the flagellar motor. The periplasmic region of the B subunit positions the stator by using the peptidoglycan-binding (PGB) motif in its periplasmic C-terminal domain to attach to the cell wall. Functional studies based on the crystal structures of the C-terminal domain of the B subunit (MotBC or PomBC) reveal that a dramatic conformational change in a characteristic α-helix allows the stator to conduct ions efficiently and bind to the PG layer. The plug and the following linker region between the transmembrane (TM) and PG-binding domains of the B subunit function in regulating the ion conductance. In Vibrio spp., the transmembrane protein FliL and the periplasmic MotX and MotY proteins also contribute to the motor function. In this review, we describe the functional and structural changes which the stator units undergo to regulate the activity of the stator to drive flagellar rotation.
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Affiliation(s)
- Michio Homma
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Japan
| | - Seiji Kojima
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Japan
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14
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Mutations in the stator protein PomA affect switching of rotational direction in bacterial flagellar motor. Sci Rep 2022; 12:2979. [PMID: 35194097 PMCID: PMC8863984 DOI: 10.1038/s41598-022-06947-5] [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: 09/17/2021] [Accepted: 02/03/2022] [Indexed: 12/03/2022] Open
Abstract
The flagellar motor rotates bi-directionally in counter-clockwise (CCW) and clockwise (CW) directions. The motor consists of a stator and a rotor. Recent structural studies have revealed that the stator is composed of a pentameric ring of A subunits and a dimer axis of B subunits. Highly conserved charged and neighboring residues of the A subunit interacts with the rotor, generating torque through a gear-like mechanism. The rotational direction is controlled by chemotaxis signaling transmitted to the rotor, with less evidence for the stator being involved. In this study, we report novel mutations that affect the switching of the rotational direction at the putative interaction site of the stator to generate rotational force. Our results highlight an aspect of flagellar motor function that appropriate switching of the interaction states between the stator and rotor is critical for controlling the rotational direction.
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15
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The flagellar motor protein FliL forms a scaffold of circumferentially positioned rings required for stator activation. Proc Natl Acad Sci U S A 2022; 119:2118401119. [PMID: 35046042 PMCID: PMC8794807 DOI: 10.1073/pnas.2118401119] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/15/2021] [Indexed: 01/25/2023] Open
Abstract
Bacteria have evolved appendages called flagella that are spun by an ingenious rotary motor that harnesses electrochemical energy to power rotation. To uncover and understand nature's blueprint of this nanoscale engine, an integrative structural biology approach is required. We used a combination of mutagenesis, cryogenic electron tomography, and crystallography to reveal the architecture of a circle of rings scaffold that likely serves to organize and stabilize individual power-generating units of the flagellar motor in their active form. The knowledge about the structure–function relationships within the bacterial flagella motor is a source of inspiration for nanotechnology and can be one of the first steps toward making artificial motors on the same scale or controlling motility for medical applications. The flagellar motor stator is an ion channel nanomachine that assembles as a ring of the MotA5MotB2 units at the flagellar base. The role of accessory proteins required for stator assembly and activation remains largely enigmatic. Here, we show that one such assembly factor, the conserved protein FliL, forms an integral part of the Helicobacter pylori flagellar motor in a position that colocalizes with the stator. Cryogenic electron tomography reconstructions of the intact motor in whole wild-type cells and cells lacking FliL revealed that the periplasmic domain of FliL (FliL-C) forms 18 circumferentially positioned rings integrated with the 18 MotAB units. FliL-C formed partial rings in the crystal, and the crystal structure–based full ring model was consistent with the shape of the rings observed in situ. Our data suggest that each FliL ring is coaxially sandwiched between the MotA ring and the dimeric periplasmic MotB moiety of the stator unit and that the central hole of the FliL ring has density that is consistent with the plug/linker region of MotB in its extended, active conformation. Significant structural similarities were found between FliL-C and stomatin/prohibitin/flotillin/HflK/C domains of scaffolding proteins, suggesting that FliL acts as a scaffold. The binding energy released upon association of FliL with the stator units could be used to power the release of the plug helices. The finding that isolated FliL-C forms stable partial rings provides an insight into the putative mechanism by which the FliL rings assemble around the stator units.
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16
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Nishikino T, Sagara Y, Terashima H, Homma M, Kojima S. Hoop-like role of the cytosolic interface helix in Vibrio PomA, an ion-conducting membrane protein, in the bacterial flagellar motor. J Biochem 2022; 171:443-450. [PMID: 35015887 DOI: 10.1093/jb/mvac001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 01/04/2022] [Indexed: 11/13/2022] Open
Abstract
Vibrio has a polar flagellum driven by sodium ions for swimming. The force-generating stator unit consists of PomA and PomB. PomA contains four-transmembrane regions and a cytoplasmic domain of approximately 100 residues which interacts with the rotor protein, FliG, to be important for the force generation of rotation. The three-dimensional structure of the stator shows that the cytosolic interface (CI) helix of PomA is located parallel to the inner membrane. In this study, we investigated the function of CI helix and its role as stator. Systematic proline mutagenesis showed that residues K64, F66, and M67 were important for this function. The mutant stators did not assemble around the rotor. Moreover, the growth defect caused by PomB plug deletion was suppressed by these mutations. We speculate that the mutations affect the structure of the helices extending from TM3 and TM4 and reduce the structural stability of the stator complex. This study suggests that the helices parallel to the inner membrane play important roles in various processes, such as the hoop-like function in securing the stability of the stator complex and the ion conduction pathway, which may lead to the elucidation of the ion permeation and assembly mechanism of the stator.
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Affiliation(s)
- Tatsuro Nishikino
- Institute for protein research, Osaka University, 3-2 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Yugo Sagara
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan
| | - Hiroyuki Terashima
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan.,Department of bacteriology, Institute of Tropical Medicine (NEKKEN), Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan
| | - Michio Homma
- 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
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17
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Takekawa N, Nishikino T, Hori K, Kojima S, Imada K, Homma M. ZomB is essential for chemotaxis of Vibrio alginolyticus by the rotational direction control of the polar flagellar motor. Genes Cells 2021; 26:927-937. [PMID: 34487583 DOI: 10.1111/gtc.12895] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 08/30/2021] [Accepted: 09/01/2021] [Indexed: 11/28/2022]
Abstract
Bacteria exhibit chemotaxis by controlling flagellar rotation to move toward preferred places or away from nonpreferred places. The change in rotation is triggered by the binding of the chemotaxis signaling protein CheY-phosphate (CheY-P) to the C-ring in the flagellar motor. Some specific bacteria, including Vibrio spp. and Shewanella spp., have a single transmembrane protein called ZomB. ZomB is essential for controlling the flagellar rotational direction in Shewanella putrefaciens and Vibrio parahaemolyticus. In this study, we confirmed that the zomB deletion results only in the counterclockwise (CCW) rotation of the motor in Vibrio alginolyticus as previously reported in other bacteria. We found that ZomB is not required for a clockwise-locked phenotype caused by mutations in fliG and fliM, and that ZomB is essential for CW rotation induced by overproduction of CheY-P. Purified ZomB proteins form multimers, suggesting that ZomB may function as a homo-oligomer. These observations imply that ZomB interacts with protein(s) involved in either flagellar motor rotation, chemotaxis, or both. We provide the evidence that ZomB is a new player in chemotaxis and is required for the rotational control in addition to CheY in Vibrio alginolyticus.
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Affiliation(s)
- Norihiro Takekawa
- Department of Macromolecular Science, Graduate School of Science, Osaka University, Toyonaka, Japan
| | - Tatsuro Nishikino
- Research Center for Next-Generation Protein Sciences, Institute for Protein Research, Osaka University, Suita, Japan
| | - Kiyoshiro Hori
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Japan
| | - Seiji Kojima
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Japan
| | - Katsumi Imada
- Department of Macromolecular Science, Graduate School of Science, Osaka University, Toyonaka, Japan
| | - Michio Homma
- Division of Biological Science, Graduate School of Science, Nagoya University, Nagoya, Japan
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18
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Putative Spanner Function of the Vibrio PomB Plug Region in the Stator Rotation Model for Flagellar Motor. J Bacteriol 2021; 203:e0015921. [PMID: 34096782 DOI: 10.1128/jb.00159-21] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Bacterial flagella are the best-known rotational organelles in the biological world. The spiral-shaped flagellar filaments that extend from the cell surface rotate like a screw to create a propulsive force. At the base of the flagellar filament lies a protein motor that consists of a stator and a rotor embedded in the membrane. The stator is composed of two types of membrane subunits, PomA (similar to MotA in Escherichia coli) and PomB (similar to MotB in E. coli), which are energy converters that assemble around the rotor to couple rotation with the ion flow. Recently, stator structures, where two MotB molecules are inserted into the center of a ring made of five MotA molecules, were reported. This structure inspired a model in which the MotA ring rotates around the MotB dimer in response to ion influx. Here, we focus on the Vibrio PomB plug region, which is involved in flagellar motor activation. We investigated the plug region using site-directed photo-cross-linking and disulfide cross-linking experiments. Our results demonstrated that the plug interacts with the extracellular short loop region of PomA, which is located between transmembrane helices 3 and 4. Although the motor stopped rotating after cross-linking, its function recovered after treatment with a reducing reagent that disrupted the disulfide bond. Our results support the hypothesis, which has been inferred from the stator structure, that the plug region terminates the ion influx by blocking the rotation of the rotor as a spanner. IMPORTANCE The biological flagellar motor resembles a mechanical motor. It is composed of a stator and a rotor. The force is transmitted to the rotor by the gear-like stator movements. It has been proposed that the pentamer of MotA subunits revolves around the axis of the B subunit dimer in response to ion flow. The plug region of the B subunit regulates the ion flow. Here, we demonstrated that the ion flow was terminated by cross-linking the plug region of PomB with PomA. These findings support the rotation hypothesis and explain the role of the plug region in blocking the rotation of the stator unit.
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19
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Hu H, Santiveri M, Wadhwa N, Berg HC, Erhardt M, Taylor NMI. Structural basis of torque generation in the bi-directional bacterial flagellar motor. Trends Biochem Sci 2021; 47:160-172. [PMID: 34294545 DOI: 10.1016/j.tibs.2021.06.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2021] [Revised: 06/16/2021] [Accepted: 06/18/2021] [Indexed: 12/11/2022]
Abstract
The flagellar stator unit is an oligomeric complex of two membrane proteins (MotA5B2) that powers bi-directional rotation of the bacterial flagellum. Harnessing the ion motive force across the cytoplasmic membrane, the stator unit operates as a miniature rotary motor itself to provide torque for rotation of the flagellum. Recent cryo-electron microscopic (cryo-EM) structures of the stator unit provided novel insights into its assembly, function, and subunit stoichiometry, revealing the ion flux pathway and the torque generation mechanism. Furthermore, in situ cryo-electron tomography (cryo-ET) studies revealed unprecedented details of the interactions between stator unit and rotor. In this review, we summarize recent advances in our understanding of the structure and function of the flagellar stator unit, torque generation, and directional switching of the motor.
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Affiliation(s)
- Haidai Hu
- Structural Biology of Molecular Machines Group, Protein Structure & Function Program, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark
| | - Mònica Santiveri
- Structural Biology of Molecular Machines Group, Protein Structure & Function Program, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark
| | - Navish Wadhwa
- Department of Molecular and Cellular Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA; Rowland Institute at Harvard, Harvard University, 100 Edwin H. Land Blvd, Cambridge, MA 02142, USA
| | - Howard C Berg
- Department of Molecular and Cellular Biology, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA; Rowland Institute at Harvard, Harvard University, 100 Edwin H. Land Blvd, Cambridge, MA 02142, USA
| | - Marc Erhardt
- Institut für Biologie/Bakterienphysiologie, Humboldt-Universität zu Berlin, Philippstr. 13, 10115 Berlin, Germany
| | - Nicholas M I Taylor
- Structural Biology of Molecular Machines Group, Protein Structure & Function Program, Novo Nordisk Foundation Center for Protein Research, Faculty of Health and Medical Sciences, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen, Denmark.
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20
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Takekawa N, Nishikino T, Yamashita T, Hori K, Onoue Y, Ihara K, Kojima S, Homma M, Imada K. A slight bending of an α-helix in FliM creates a counterclockwise-locked structure of the flagellar motor in Vibrio. J Biochem 2021; 170:531-538. [PMID: 34143212 DOI: 10.1093/jb/mvab074] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2021] [Accepted: 06/01/2021] [Indexed: 11/13/2022] Open
Abstract
Many bacteria swim by rotating flagella. The chemotaxis system controls the direction of flagellar rotation. Vibrio alginolyticus, which has a single polar flagellum, swims smoothly by rotating the flagellar motor counterclockwise (CCW) in response to attractants. In response to repellents, the motor frequently switches its rotational direction between CCW and clockwise (CW). We isolated a mutant strain that swims with a CW-locked rotation of the flagellum, which pulls rather than pushes the cell. This CW phenotype arises from a R49P substitution in FliM, which is the component in the C-ring of the motor that binds the chemotaxis signaling protein, phosphorylated CheY. However, this phenotype is independent of CheY, indicating that the mutation produces a CW conformation of the C-ring in the absence of CheY. The crystal structure of FliM with the R49P substitution showed a conformational change in the N-terminal α-helix of the middle domain of FliM (FliMM). This helix should mediates FliM-FliM interaction. The structural models of wild-type and mutant C-ring showed that the relatively small conformational change in FliMM induces a drastic rearrangement of the conformation of the FliMM domain that generates a CW conformation of the C-ring.
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Affiliation(s)
- Norihiro Takekawa
- Department of Macromolecular Science, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan
| | - Tatsuro Nishikino
- Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan.,Research Center for Next-Generation Protein Sciences, Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Toshiki Yamashita
- Department of Macromolecular Science, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan
| | - Kiyoshiro Hori
- Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan
| | - Yasuhiro Onoue
- Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan
| | - Kunio Ihara
- Center for Gene Research, Nagoya University, Furocho, Nagoya, Aichi 464-8602, Japan
| | - Seiji Kojima
- Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan
| | - Michio Homma
- Division of Biological Science, Graduate School of Science, Nagoya University, Furo-cho, Chikusa-ku, Nagoya, Aichi 464-8602, Japan
| | - Katsumi Imada
- Department of Macromolecular Science, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan
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21
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Tan J, Zhang X, Wang X, Xu C, Chang S, Wu H, Wang T, Liang H, Gao H, Zhou Y, Zhu Y. Structural basis of assembly and torque transmission of the bacterial flagellar motor. Cell 2021; 184:2665-2679.e19. [PMID: 33882274 DOI: 10.1016/j.cell.2021.03.057] [Citation(s) in RCA: 61] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 02/28/2021] [Accepted: 03/29/2021] [Indexed: 12/11/2022]
Abstract
The bacterial flagellar motor is a supramolecular protein machine that drives rotation of the flagellum for motility, which is essential for bacterial survival in different environments and a key determinant of pathogenicity. The detailed structure of the flagellar motor remains unknown. Here we present an atomic-resolution cryoelectron microscopy (cryo-EM) structure of the bacterial flagellar motor complexed with the hook, consisting of 175 subunits with a molecular mass of approximately 6.3 MDa. The structure reveals that 10 peptides protruding from the MS ring with the FlgB and FliE subunits mediate torque transmission from the MS ring to the rod and overcome the symmetry mismatch between the rotational and helical structures in the motor. The LP ring contacts the distal rod and applies electrostatic forces to support its rotation and torque transmission to the hook. This work provides detailed molecular insights into the structure, assembly, and torque transmission mechanisms of the flagellar motor.
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Affiliation(s)
- Jiaxing Tan
- Department of Biophysics and Department of Pathology of Sir Run Run Shaw Hospital, Life Sciences Institute and School of Medicine, Zhejiang University, Hangzhou, Zhejiang 310058, China; The MOE Key Laboratory for Biosystems Homeostasis & Protection and Zhejiang Provincial Key Laboratory of Cancer Molecular Cell Biology, Life Sciences Institute, Zhejiang University, Hangzhou, Zhejiang 310058, China; Institute of Microbiology, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Xing Zhang
- Department of Biophysics and Department of Pathology of Sir Run Run Shaw Hospital, Life Sciences Institute and School of Medicine, Zhejiang University, Hangzhou, Zhejiang 310058, China; Center of Cryo Electron Microscopy, Zhejiang University, Hangzhou, Zhejiang 310058, China; Liangzhu Laboratory, Zhejiang University Medical Center, Hangzhou, Zhejiang 311121, China.
| | - Xiaofei Wang
- Department of Biophysics and Department of Pathology of Sir Run Run Shaw Hospital, Life Sciences Institute and School of Medicine, Zhejiang University, Hangzhou, Zhejiang 310058, China; The MOE Key Laboratory for Biosystems Homeostasis & Protection and Zhejiang Provincial Key Laboratory of Cancer Molecular Cell Biology, Life Sciences Institute, Zhejiang University, Hangzhou, Zhejiang 310058, China; The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Caihuang Xu
- Department of Biophysics and Department of Pathology of Sir Run Run Shaw Hospital, Life Sciences Institute and School of Medicine, Zhejiang University, Hangzhou, Zhejiang 310058, China; Center of Cryo Electron Microscopy, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Shenghai Chang
- Department of Biophysics and Department of Pathology of Sir Run Run Shaw Hospital, Life Sciences Institute and School of Medicine, Zhejiang University, Hangzhou, Zhejiang 310058, China; Center of Cryo Electron Microscopy, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Hangjun Wu
- Department of Biophysics and Department of Pathology of Sir Run Run Shaw Hospital, Life Sciences Institute and School of Medicine, Zhejiang University, Hangzhou, Zhejiang 310058, China; Center of Cryo Electron Microscopy, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Ting Wang
- Department of Biophysics and Department of Pathology of Sir Run Run Shaw Hospital, Life Sciences Institute and School of Medicine, Zhejiang University, Hangzhou, Zhejiang 310058, China; The MOE Key Laboratory for Biosystems Homeostasis & Protection and Zhejiang Provincial Key Laboratory of Cancer Molecular Cell Biology, Life Sciences Institute, Zhejiang University, Hangzhou, Zhejiang 310058, China; Institute of Microbiology, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Huihui Liang
- Institute of Microbiology, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Haichun Gao
- Institute of Microbiology, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Yan Zhou
- Department of Biophysics and Department of Pathology of Sir Run Run Shaw Hospital, Life Sciences Institute and School of Medicine, Zhejiang University, Hangzhou, Zhejiang 310058, China; The MOE Key Laboratory for Biosystems Homeostasis & Protection and Zhejiang Provincial Key Laboratory of Cancer Molecular Cell Biology, Life Sciences Institute, Zhejiang University, Hangzhou, Zhejiang 310058, China; Institute of Microbiology, Zhejiang University, Hangzhou, Zhejiang 310058, China
| | - Yongqun Zhu
- Department of Biophysics and Department of Pathology of Sir Run Run Shaw Hospital, Life Sciences Institute and School of Medicine, Zhejiang University, Hangzhou, Zhejiang 310058, China; The MOE Key Laboratory for Biosystems Homeostasis & Protection and Zhejiang Provincial Key Laboratory of Cancer Molecular Cell Biology, Life Sciences Institute, Zhejiang University, Hangzhou, Zhejiang 310058, China; The Second Affiliated Hospital, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China; Institute of Microbiology, Zhejiang University, Hangzhou, Zhejiang 310058, China; Cancer Center, Zhejiang University, Hangzhou, Zhejiang 310058, China.
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22
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Site-directed crosslinking identifies the stator-rotor interaction surfaces in a hybrid bacterial flagellar motor. J Bacteriol 2021; 203:JB.00016-21. [PMID: 33619152 PMCID: PMC8092157 DOI: 10.1128/jb.00016-21] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The bacterial flagellum is the motility organelle powered by a rotary motor. The rotor and stator elements of the motor are located in the cytoplasmic membrane and cytoplasm. The stator units assemble around the rotor, and an ion flux (typically H+ or Na+) conducted through a channel of the stator induces conformational changes that generate rotor torque. Electrostatic interactions between the stator protein PomA in Vibrio (MotA in Escherichia coli) and the rotor protein FliG have been shown by genetic analyses, but have not been demonstrated biochemically. Here, we used site-directed photo- and disulfide-crosslinking to provide direct evidence for the interaction. We introduced a UV-reactive amino acid, p-benzoyl-L-phenylalanine (pBPA), into the cytoplasmic region of PomA or the C-terminal region of FliG in intact cells. After UV irradiation, pBPA inserted at a number of positions in PomA formed a crosslink with FliG. PomA residue K89 gave the highest yield of crosslinks, suggesting that it is the PomA residue nearest to FliG. UV-induced crosslinking stopped motor rotation, and the isolated hook-basal body contained the crosslinked products. pBPA inserted to replace residues R281 or D288 in FliG formed crosslinks with the Escherichia coli stator protein, MotA. A cysteine residue introduced in place of PomA K89 formed disulfide crosslinks with cysteine inserted in place of FliG residues R281 and D288, and some other flanking positions. These results provide the first demonstration of direct physical interaction between specific residues in FliG and PomA/MotA.ImportanceThe bacterial flagellum is a unique organelle that functions as a rotary motor. The interaction between the stator and rotor is indispensable for stator assembly into the motor and the generation of motor torque. However, the interface of the stator-rotor interaction has only been defined by mutational analysis. Here, we detected the stator-rotor interaction using site-directed photo- and disulfide-crosslinking approaches. We identified several residues in the PomA stator, especially K89, that are in close proximity to the rotor. Moreover, we identified several pairs of stator and rotor residues that interact. This study directly demonstrates the nature of the stator-rotor interaction and suggests how stator units assemble around the rotor and generate torque in the bacterial flagellar motor.
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23
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Zhou X, Roujeinikova A. The Structure, Composition, and Role of Periplasmic Stator Scaffolds in Polar Bacterial Flagellar Motors. Front Microbiol 2021; 12:639490. [PMID: 33776972 PMCID: PMC7990780 DOI: 10.3389/fmicb.2021.639490] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 02/16/2021] [Indexed: 01/10/2023] Open
Abstract
In the bacterial flagellar motor, the cell-wall-anchored stator uses an electrochemical gradient across the cytoplasmic membrane to generate a turning force that is applied to the rotor connected to the flagellar filament. Existing theoretical concepts for the stator function are based on the assumption that it anchors around the rotor perimeter by binding to peptidoglycan (P). The existence of another anchoring region on the motor itself has been speculated upon, but is yet to be supported by binding studies. Due to the recent advances in electron cryotomography, evidence has emerged that polar flagellar motors contain substantial proteinaceous periplasmic structures next to the stator, without which the stator does not assemble and the motor does not function. These structures have a morphology of disks, as is the case with Vibrio spp., or a round cage, as is the case with Helicobacter pylori. It is now recognized that such additional periplasmic components are a common feature of polar flagellar motors, which sustain higher torque and greater swimming speeds compared to peritrichous bacteria such as Escherichia coli and Salmonella enterica. This review summarizes the data available on the structure, composition, and role of the periplasmic scaffold in polar bacterial flagellar motors and discusses the new paradigm for how such motors assemble and function.
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Affiliation(s)
- Xiaotian Zhou
- Infection and Immunity Program, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia.,Department of Microbiology, Monash University, Clayton, VIC, Australia
| | - Anna Roujeinikova
- Infection and Immunity Program, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia.,Department of Microbiology, Monash University, Clayton, VIC, Australia.,Department of Biochemistry and Molecular Biology, Monash University, Clayton, VIC, Australia
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24
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Abundant Monovalent Ions as Environmental Signposts for Pathogens during Host Colonization. Infect Immun 2021; 89:IAI.00641-20. [PMID: 33526568 DOI: 10.1128/iai.00641-20] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Host colonization by a pathogen requires proper sensing and response to local environmental cues, to ensure adaptation and continued survival within the host. The ionic milieu represents a critical potential source of environmental cues, and indeed, there has been extensive study of the interplay between host and pathogen in the context of metals such as iron, zinc, and manganese, vital ions that are actively sequestered by the host. The inherent non-uniformity of the ionic milieu also extends, however, to "abundant" ions such as chloride and potassium, whose concentrations vary greatly between tissue and cellular locations, and with the immune response. Despite this, the concept of abundant ions as environmental cues and key players in host-pathogen interactions is only just emerging. Focusing on chloride and potassium, this review brings together studies across multiple bacterial and parasitic species that have begun to define both how these abundant ions are exploited as cues during host infection, and how they can be actively manipulated by pathogens during host colonization. The close links between ion homeostasis and sensing/response to different ionic signals, and the importance of studying pathogen response to cues in combination, are also discussed, while considering the fundamental insight still to be uncovered from further studies in this nascent area of inquiry.
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