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Schumacher K, Braun D, Kleigrewe K, Jung K. Motility-activating mutations upstream of flhDC reduce acid shock survival of Escherichia coli. Microbiol Spectr 2024; 12:e0054424. [PMID: 38651876 DOI: 10.1128/spectrum.00544-24] [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: 02/28/2024] [Accepted: 04/03/2024] [Indexed: 04/25/2024] Open
Abstract
Many neutralophilic bacterial species try to evade acid stress with an escape strategy, which is reflected in the increased expression of genes coding for flagellar components. Extremely acid-tolerant bacteria, such as Escherichia coli, survive the strong acid stress, e.g., in the stomach of vertebrates. Recently, we were able to show that the induction of motility genes in E. coli is strictly dependent on the degree of acid stress, i.e., they are induced under mild acid stress but not under severe acid stress. However, it was not known to what extent fine-tuned expression of motility genes is related to fitness and the ability to survive periods of acid shock. In this study, we demonstrate that the expression of FlhDC, the master regulator of flagellation, is inversely correlated with the acid shock survival of E. coli. We encountered this phenomenon when analyzing mutants from the Keio collection, in which the expression of flhDC was altered by an insertion sequence element. These results suggest a fitness trade-off between acid tolerance and motility.IMPORTANCEEscherichia coli is extremely acid-resistant, which is crucial for survival in the gastrointestinal tract of vertebrates. Recently, we systematically studied the response of E. coli to mild and severe acidic conditions using Ribo-Seq and RNA-Seq. We found that motility genes are induced at pH 5.8 but not at pH 4.4, indicating stress-dependent synthesis of flagellar components. In this study, we demonstrate that motility-activating mutations upstream of flhDC, encoding the master regulator of flagella genes, reduce the ability of E. coli to survive periods of acid shock. Furthermore, we show an inverse correlation between motility and acid survival using a chromosomal isopropyl β-D-thio-galactopyranoside (IPTG)-inducible flhDC promoter and by sampling differentially motile subpopulations from swim agar plates. These results reveal a previously undiscovered trade-off between motility and acid tolerance and suggest a differentiation of E. coli into motile and acid-tolerant subpopulations, driven by the integration of insertion sequence elements.
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Affiliation(s)
- Kilian Schumacher
- Faculty of Biology, Microbiology, Ludwig-Maximilians-Universität München, Martinsried, Germany
| | - Djanna Braun
- Faculty of Biology, Microbiology, Ludwig-Maximilians-Universität München, Martinsried, Germany
| | - Karin Kleigrewe
- Bavarian Center for Biomolecular Mass Spectrometry (BayBioMS), Technical University of Munich, Freising, Germany
| | - Kirsten Jung
- Faculty of Biology, Microbiology, Ludwig-Maximilians-Universität München, Martinsried, Germany
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2
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Gibson KH, Botting JM, Al-Otaibi N, Maitre K, Bergeron J, Starai VJ, Hoover TR. Control of the flagellation pattern in Helicobacter pylori by FlhF and FlhG. J Bacteriol 2023; 205:e0011023. [PMID: 37655916 PMCID: PMC10521351 DOI: 10.1128/jb.00110-23] [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: 03/24/2023] [Accepted: 07/06/2023] [Indexed: 09/02/2023] Open
Abstract
FlhF and FlhG control the location and number of flagella, respectively, in many polar-flagellated bacteria. The roles of FlhF and FlhG are not well characterized in bacteria that have multiple polar flagella, such as Helicobacter pylori. Deleting flhG in H. pylori shifted the flagellation pattern where most cells had approximately four flagella to a wider and more even distribution in flagellar number. As reported in other bacteria, deleting flhF in H. pylori resulted in reduced motility, hypoflagellation, and the improper localization of flagella to nonpolar sites. Motile variants of H. pylori ∆flhF mutants that had a higher proportion of flagella localizing correctly to the cell pole were isolated, but we were unable to identify the genetic determinants responsible for the increased localization of flagella to the cell pole. One motile variant though produced more flagella than the ΔflhF parental strain, which apparently resulted from a missense mutation in fliF (encodes the MS ring protein), which changed Asn-255 to aspartate. Recombinant FliFN255D, but not recombinant wild-type FliF, formed ordered ring-like assemblies in vitro that were ~50 nm wide and displayed the MS ring architecture. We infer from these findings that the FliFN225D variant forms the MS ring more effectively in vivo in the absence of FlhF than wild-type FliF. IMPORTANCE Helicobacter pylori colonizes the human stomach where it can cause a variety of diseases, including peptic ulcer disease and gastric cancer. H. pylori uses flagella for motility, which is required for host colonization. FlhG and FlhF control the flagellation patterns in many bacteria. We found that in H. pylori, FlhG ensures that cells have approximately equal number of flagella and FlhF is needed for flagellum assembly and localization. FlhF is proposed to facilitate the assembly of FliF into the MS ring, which is one of the earliest structures formed in flagellum assembly. We identified a FliF variant that assembles the MS ring in the absence of FlhF, which supports the proposed role of FlhF in facilitating MS ring assembly.
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Affiliation(s)
| | - Jack M. Botting
- Department of Microbiology, University of Georgia, Athens, Georgia, USA
| | - Natalie Al-Otaibi
- Randall Division of Cell and Molecular Biophysics, King’s College London, London, United Kingdom
| | - Kriti Maitre
- Randall Division of Cell and Molecular Biophysics, King’s College London, London, United Kingdom
| | - Julien Bergeron
- Randall Division of Cell and Molecular Biophysics, King’s College London, London, United Kingdom
| | - Vincent J. Starai
- Department of Microbiology, University of Georgia, Athens, Georgia, USA
| | - Timothy R. Hoover
- Department of Microbiology, University of Georgia, Athens, Georgia, USA
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3
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Tao A, Liu G, Zhang R, Yuan J. Precise Measurement of the Stoichiometry of the Adaptive Bacterial Flagellar Switch. mBio 2023; 14:e0018923. [PMID: 36946730 PMCID: PMC10128058 DOI: 10.1128/mbio.00189-23] [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: 03/23/2023] Open
Abstract
The cytoplasmic ring (C-ring) of the bacterial flagellar motor controls the motor rotation direction, thereby controlling bacterial run-and-tumble behavior. The C-ring has been shown to undergo adaptive remodeling in response to changes in motor directional bias. However, the stoichiometry and arrangement of the C-ring is still unclear due to contradiction between the results from fluorescence studies and cryo-electron microscopy (cryo-EM) structural analysis. Here, by using the copy number of FliG molecules (34) in the C-ring as a reference, we precisely measured the copy numbers of FliM molecules in motors rotating exclusively counterclockwise (CCW) and clockwise (CW). We surprisingly found that there are on average 45 and 58 FliM molecules in CW and CCW rotating motors, respectively, which are much higher than previous estimates. Our results suggested a new mechanism of C-ring adaptation, that is, extra FliM molecules could be bound to the primary C-ring with probability depending on the motor rotational direction. We further confirmed that all of the FliM molecules in the C-ring function in chemotaxis signaling transduction because all of them could be bound by the chemotactic response regulator CheY-P. Our measurements provided new insights into the structure and arrangement of the flagellar switch. IMPORTANCE The bacterial flagellar switch can undergo adaptive remodeling in response to changes in motor rotation direction, thereby shifting its operating point to match the output of the chemotaxis signaling pathway. However, it remains unclear how the flagellar switch accomplishes this adaptive remodeling. Here, via precise fluorescence studies, we measured the absolute copy numbers of the critical component in the switch for motors rotating counterclockwise and clockwise, obtaining much larger numbers than previous relative estimates. Our results suggested a new mechanism of adaptive remodeling of the flagellar switch and provided new insights for updating the conformation spread model of the switch.
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Affiliation(s)
- Antai Tao
- Department of Physics, University of Science and Technology of China, Hefei, Anhui, China
| | - Guangzhe Liu
- Wenzhou Institute, University of Chinese Academy of Science, Wenzhou, Zhejiang, P.R. China
- School of Engineering and Science, University of Chinese Academy of Science, Beijing, P.R. China
| | - Rongjing Zhang
- Department of Physics, University of Science and Technology of China, Hefei, Anhui, China
| | - Junhua Yuan
- Department of Physics, University of Science and Technology of China, Hefei, Anhui, China
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4
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Feng LJ, Zhang KX, Shi ZL, Zhu FP, Yuan XZ, Zong WS, Song C. Aged microplastics enhance their interaction with ciprofloxacin and joint toxicity on Escherichia coli. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2022; 247:114218. [PMID: 36279636 DOI: 10.1016/j.ecoenv.2022.114218] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Revised: 10/12/2022] [Accepted: 10/19/2022] [Indexed: 06/16/2023]
Abstract
Microplastics (MPs) in natural environments undergo complex aging processes, changing their interactions with coexisting antibiotics, and posing unpredictable ecological risks. However, the joint toxicity of aged MPs (aMPs) and antibiotics to bacteria, especially at the molecular level, is unclear. In this study, non-thermal plasma technology was used to simultaneously simulate various radical oxidation and physical reactions that occur naturally in the environment, breaking the limitation of simple aging process in laboratory aging technologies. After aging, we investigated the altered properties of aMPs, their interactions with ciprofloxacin (CIP), and the molecular responses of E. coli exposed to pristine MPs (13.5 mg/L), aMPs (13.5 mg/L), and CIP (2 μg/L) individually or simultaneously. aMPs bound far more CIP to their surfaces than pristine MPs, especially in freshwater ecosystems. Notably, the growth of E. coli exposed to aMPs alone was inhibited, whereas pristine MPs exposure didn't affect the growth of E. coli. Moreover, the most differentially expressed genes in E. coli were induced by the coexposure of aMPs and CIP. Although E. coli depended on chemotaxis to improve its flagellar rotation and escaped the stress of pollutants, the coexposure of aMPs and CIP still caused cell membrane damage, oxidative stress, obstruction of DNA replication, and osmotic imbalance in E. coli. This study filled the knowledge gap between the toxicity of aMPs and pristine MPs coexisting with antibiotics at the transcription level, helping in the accurate assessment of the potential risks of MPs to the environment.
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Affiliation(s)
- Li-Juan Feng
- College of Geography and Environment, Shandong Normal University, Jinan, Shandong 250014, PR China; Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao, Shandong 266237, PR China; Hebei Key Laboratory of Wetland Ecology and Conservation, Hengshui, Hebei 053000, PR China
| | - Kai-Xin Zhang
- Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao, Shandong 266237, PR China; School of Eco-Environment, Hebei University, Baoding, Hebei 071002, PR China
| | - Zong-Lin Shi
- Hebei Key Laboratory of Wetland Ecology and Conservation, Hengshui, Hebei 053000, PR China; Department of Life Science, Hengshui College, Hengshui, Hebei 053000, PR China
| | - Fan-Ping Zhu
- Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao, Shandong 266237, PR China
| | - Xian-Zheng Yuan
- Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao, Shandong 266237, PR China
| | - Wan-Song Zong
- College of Geography and Environment, Shandong Normal University, Jinan, Shandong 250014, PR China.
| | - Chao Song
- Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Qingdao, Shandong 266237, PR China.
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5
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FliL Differentially Interacts with Two Stator Systems To Regulate Flagellar Motor Output in Pseudomonas aeruginosa. Appl Environ Microbiol 2022; 88:e0153922. [PMID: 36286538 PMCID: PMC9680632 DOI: 10.1128/aem.01539-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
FliL emerged as a modulator of flagellar motor function in several bacterial species, but its function in
Pseudomonas aeruginosa
was unknown. Here, by performing single-motor studies using a bead assay, we elucidated its effects on the flagellar motor in
P. aeruginosa
.
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6
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Zhang D, Li SHJ, King CG, Wingreen NS, Gitai Z, Li Z. Global and gene-specific translational regulation in Escherichia coli across different conditions. PLoS Comput Biol 2022; 18:e1010641. [PMID: 36264977 PMCID: PMC9624429 DOI: 10.1371/journal.pcbi.1010641] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 11/01/2022] [Accepted: 10/06/2022] [Indexed: 11/05/2022] Open
Abstract
How well mRNA transcript levels represent protein abundances has been a controversial issue. Particularly across different environments, correlations between mRNA and protein exhibit remarkable variability from gene to gene. Translational regulation is likely to be one of the key factors contributing to mismatches between mRNA level and protein abundance in bacteria. Here, we quantified genome-wide transcriptome and relative translation efficiency (RTE) under 12 different conditions in Escherichia coli. By quantifying the mRNA-RTE correlation both across genes and across conditions, we uncovered a diversity of gene-specific translational regulations, cooperating with transcriptional regulations, in response to carbon (C), nitrogen (N), and phosphate (P) limitations. Intriguingly, we found that many genes regulating translation are themselves subject to translational regulation, suggesting possible feedbacks. Furthermore, a random forest model suggests that codon usage partially predicts a gene's cross-condition variability in translation efficiency; such cross-condition variability tends to be an inherent quality of a gene, independent of the specific nutrient limitations. These findings broaden the understanding of translational regulation under different environments and provide novel strategies for the control of translation in synthetic biology. In addition, our data offers a resource for future multi-omics studies.
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Affiliation(s)
- Di Zhang
- Center for Quantitative Biology, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
- Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
| | - Sophia Hsin-Jung Li
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America
- Institute of Bioengineering, School of Life Sciences, Swiss Federal Institute of Technology Lausanne, Lausanne, Switzerland
- Global Health Institute, School of Life Sciences, Swiss Federal Institute of Technology Lausanne, Lausanne, Switzerland
| | - Christopher G. King
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America
| | - Ned S. Wingreen
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey, United States of America
- * E-mail: (NSW); (ZG); (ZL)
| | - Zemer Gitai
- Department of Molecular Biology, Princeton University, Princeton, New Jersey, United States of America
- * E-mail: (NSW); (ZG); (ZL)
| | - Zhiyuan Li
- Center for Quantitative Biology, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
- Peking-Tsinghua Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
- * E-mail: (NSW); (ZG); (ZL)
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7
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Gilzer D, Baum E, Lieske N, Kowal JL, Niemann HH. Crystals of SctV from different species reveal variable symmetry for the cytosolic domain of the type III secretion system export gate. Acta Crystallogr F Struct Biol Commun 2022; 78:386-394. [PMID: 36322424 PMCID: PMC9629515 DOI: 10.1107/s2053230x22009736] [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: 07/06/2022] [Accepted: 10/04/2022] [Indexed: 11/06/2022] Open
Abstract
Type III secretion systems (T3SSs) are proteinaceous devices employed by Gram-negative bacteria to directly transport proteins into a host cell. Substrate recognition and secretion are strictly regulated by the export apparatus of the so-called injectisome. The export gate SctV engages chaperone-bound substrates of the T3SS in its nonameric cytoplasmic domain. Here, the purification and crystallization of the cytoplasmic domains of SctV from Photorhabdus luminescens (LscVC) and Aeromonas hydrophila (AscVC) are reported. Self-rotation functions revealed that LscVC forms oligomers with either eightfold or ninefold symmetry in two different crystal forms. Similarly, AscVC was found to exhibit tenfold rotational symmetry. These are the first instances of SctV proteins forming non-nonameric oligomers.
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Affiliation(s)
- Dominic Gilzer
- Department of Chemistry, Bielefeld University, Universitätsstrasse 25, 33615 Bielefeld, Germany
| | - Eileen Baum
- Department of Chemistry, Bielefeld University, Universitätsstrasse 25, 33615 Bielefeld, Germany
| | - Nele Lieske
- Department of Chemistry, Bielefeld University, Universitätsstrasse 25, 33615 Bielefeld, Germany
| | - Julia L. Kowal
- Department of Chemistry, Bielefeld University, Universitätsstrasse 25, 33615 Bielefeld, Germany
| | - Hartmut H. Niemann
- Department of Chemistry, Bielefeld University, Universitätsstrasse 25, 33615 Bielefeld, Germany,Correspondence e-mail:
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8
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Gupta R, Yuan J, Lele PP. Bacterial Proprioception: Can a Bacterium Sense Its Movement? Front Microbiol 2022; 13:928408. [PMID: 35875555 PMCID: PMC9302961 DOI: 10.3389/fmicb.2022.928408] [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: 04/25/2022] [Accepted: 06/16/2022] [Indexed: 11/13/2022] Open
Abstract
The evolution of the bacterial flagellum gave rise to motility and repurposing of a signaling network, now termed the chemotaxis network, enabled biasing of cell movements. This made it possible for the bacterium to seek out favorable chemical environments. To enable chemotaxis, the chemotaxis network sensitively detects extracellular chemical stimuli and appropriately modulates flagellar functions. Additionally, the flagellar motor itself is capable of detecting mechanical stimuli and adapts its structure and function in response, likely triggering a transition from planktonic to surface-associated lifestyles. Recent work has shown a link between the flagellar motor's response to mechanical stimuli and the chemotactic output. Here, we elaborate on this link and discuss how it likely helps the cell sense and adapt to changes in its swimming speeds in different environments. We discuss the mechanism whereby the motor precisely tunes its chemotaxis output under different mechanical loads, analogous to proprioception in higher order organisms. We speculate on the roles bacterial proprioception might play in a variety of phenomena including the transition to surface-associated lifestyles such as swarming and biofilms.
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Affiliation(s)
- Rachit Gupta
- Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, TX, United States
| | - Junhua Yuan
- Department of Physics, University of Science and Technology of China, Hefei, China
| | - Pushkar P Lele
- Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, TX, United States
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9
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Discovery of a Novel Inner Membrane-Associated Bacterial Structure Related to the Flagellar Type III Secretion System. J Bacteriol 2022; 204:e0014422. [PMID: 35862756 PMCID: PMC9380563 DOI: 10.1128/jb.00144-22] [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] [Indexed: 11/24/2022] Open
Abstract
The bacterial flagellar type III secretion system (fT3SS) is a suite of membrane-embedded and cytoplasmic proteins responsible for building the flagellar motility machinery. Homologous nonflagellar (NF-T3SS) proteins form the injectisome machinery that bacteria use to deliver effector proteins into eukaryotic cells, and other family members were recently reported to be involved in the formation of membrane nanotubes. Here, we describe a novel, evolutionarily widespread, hat-shaped structure embedded in the inner membranes of bacteria, of yet-unidentified function, that is present in species containing fT3SS. Mutant analysis suggests a relationship between this novel structure and the fT3SS, but not the NF-T3SS. While the function of this novel structure remains unknown, we hypothesize that either some of the fT3SS proteins assemble within the hat-like structure, perhaps including the fT3SS core complex, or that fT3SS components regulate other proteins that form part of this novel structure. IMPORTANCE The type III secretion system (T3SS) is a fascinating suite of proteins involved in building diverse macromolecular systems, including the bacterial flagellar motility machine, the injectisome machinery that bacteria use to inject effector proteins into host cells, and probably membrane nanotubes which connect bacterial cells. Here, we accidentally discovered a novel inner membrane-associated complex related to the flagellar T3SS. Examining our lab database, which is comprised of more than 40,000 cryo-tomograms of dozens of species, we discovered that this novel structure is both ubiquitous and ancient, being present in highly divergent classes of bacteria. Discovering a novel, widespread structure related to what are among the best-studied molecular machines in bacteria will open new venues for research aiming at understanding the function and evolution of T3SS proteins.
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10
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Kaplan M, Oikonomou CM, Wood CR, Chreifi G, Subramanian P, Ortega DR, Chang Y, Beeby M, Shaffer CL, Jensen GJ. Novel transient cytoplasmic rings stabilize assembling bacterial flagellar motors. EMBO J 2022; 41:e109523. [PMID: 35301732 PMCID: PMC9108667 DOI: 10.15252/embj.2021109523] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2021] [Revised: 01/31/2022] [Accepted: 02/16/2022] [Indexed: 12/20/2022] Open
Abstract
The process by which bacterial cells build their intricate flagellar motility apparatuses has long fascinated scientists. Our understanding of this process comes mainly from studies of purified flagella from two species, Escherichia coli and Salmonella enterica. Here, we used electron cryo-tomography (cryo-ET) to image the assembly of the flagellar motor in situ in diverse Proteobacteria: Hylemonella gracilis, Helicobacter pylori, Campylobacter jejuni, Pseudomonas aeruginosa, Pseudomonas fluorescens, and Shewanella oneidensis. Our results reveal the in situ structures of flagellar intermediates, beginning with the earliest flagellar type III secretion system core complex (fT3SScc) and MS-ring. In high-torque motors of Beta-, Gamma-, and Epsilon-proteobacteria, we discovered novel cytoplasmic rings that interact with the cytoplasmic torque ring formed by FliG. These rings, associated with the MS-ring, assemble very early and persist until the stators are recruited into their periplasmic ring; in their absence the stator ring does not assemble. By imaging mutants in Helicobacter pylori, we found that the fT3SScc proteins FliO and FliQ are required for the assembly of these novel cytoplasmic rings. Our results show that rather than a simple accretion of components, flagellar motor assembly is a dynamic process in which accessory components interact transiently to assist in building the complex nanomachine.
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Affiliation(s)
- Mohammed Kaplan
- Division of Biology and Biological EngineeringCalifornia Institute of TechnologyPasadenaCAUSA
| | - Catherine M Oikonomou
- Division of Biology and Biological EngineeringCalifornia Institute of TechnologyPasadenaCAUSA
| | - Cecily R Wood
- Department of Veterinary ScienceUniversity of KentuckyLexingtonKYUSA
| | - Georges Chreifi
- Division of Biology and Biological EngineeringCalifornia Institute of TechnologyPasadenaCAUSA
| | - Poorna Subramanian
- Division of Biology and Biological EngineeringCalifornia Institute of TechnologyPasadenaCAUSA
| | - Davi R Ortega
- Division of Biology and Biological EngineeringCalifornia Institute of TechnologyPasadenaCAUSA
| | - Yi‐Wei Chang
- Department of Biochemistry and BiophysicsPerelman School of MedicineUniversity of PennsylvaniaPhiladelphiaPAUSA
| | - Morgan Beeby
- Department of Life SciencesImperial College LondonLondonUK
| | - Carrie L Shaffer
- Department of Veterinary ScienceUniversity of KentuckyLexingtonKYUSA
- Department of Microbiology, Immunology, and Molecular GeneticsUniversity of KentuckyLexingtonKYUSA
- Department of Pharmaceutical SciencesUniversity of KentuckyLexingtonKYUSA
| | - Grant J Jensen
- Division of Biology and Biological EngineeringCalifornia Institute of TechnologyPasadenaCAUSA
- Department of Chemistry and BiochemistryBrigham Young UniversityProvoUTUSA
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11
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Tupiņa D, Krah A, Marzinek JK, Zuzic L, Moverley AA, Constantinidou C, Bond PJ. Bridging the N-terminal and middle domains in FliG of the flagellar rotor. Curr Res Struct Biol 2022; 4:59-67. [PMID: 35345452 PMCID: PMC8956890 DOI: 10.1016/j.crstbi.2022.02.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 01/28/2022] [Accepted: 02/28/2022] [Indexed: 11/27/2022] Open
Abstract
Flagella are necessary for bacterial movement and contribute to various aspects of virulence. They are complex cylindrical structures built of multiple molecular rings with self-assembly properties. The flagellar rotor is composed of the MS-ring and the C-ring. The FliG protein of the C-ring is central to flagellar assembly and function due to its roles in linking the C-ring with the MS-ring and in torque transmission from stator to rotor. No high-resolution structure of an assembled C-ring has been resolved to date, and the conformation adopted by FliG within the ring is unclear due to variations in available crystallographic data. Here, we use molecular dynamics (MD) simulations to study the conformation and dynamics of FliG in different states of assembly, including both in physiologically relevant and crystallographic lattice environments. We conclude that the linker between the FliG N-terminal and middle domain likely adopts an extended helical conformation in vivo, in contrast with the contracted conformation observed in some previous X-ray studies. We further support our findings with integrative model building of full-length FliG and a FliG ring model that is compatible with cryo-electron tomography (cryo-ET) and electron microscopy (EM) densities of the C-ring. Collectively, our study contributes to a better mechanistic understanding of the flagellar rotor assembly and its function.
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12
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Mariano G, Faba-Rodriguez R, Bui S, Zhao W, Ross J, Tzokov SB, Bergeron JRC. Oligomerization of the FliF Domains Suggests a Coordinated Assembly of the Bacterial Flagellum MS Ring. Front Microbiol 2022; 12:781960. [PMID: 35087486 PMCID: PMC8786727 DOI: 10.3389/fmicb.2021.781960] [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: 09/23/2021] [Accepted: 12/08/2021] [Indexed: 12/30/2022] Open
Abstract
The bacterial flagellum is a complex, self-assembling macromolecular machine that powers bacterial motility. It plays diverse roles in bacterial virulence, including aiding in colonization and dissemination during infection. The flagellum consists of a filamentous structure protruding from the cell, and of the basal body, a large assembly that spans the cell envelope. The basal body is comprised of over 20 different proteins forming several concentric ring structures, termed the M- S- L- P- and C-rings, respectively. In particular, the MS rings are formed by a single protein FliF, which consists of two trans-membrane helices anchoring it to the inner membrane and surrounding a large periplasmic domain. Assembly of the MS ring, through oligomerization of FliF, is one of the first steps of basal body assembly. Previous computational analysis had shown that the periplasmic region of FliF consists of three structurally similar domains, termed Ring-Building Motif (RBM)1, RBM2, and RBM3. The structure of the MS-ring has been reported recently, and unexpectedly shown that these three domains adopt different symmetries, with RBM3 having a 34-mer stoichiometry, while RBM2 adopts two distinct positions in the complex, including a 23-mer ring. This observation raises some important question on the assembly of the MS ring, and the formation of this symmetry mismatch within a single protein. In this study, we analyze the oligomerization of the individual RBM domains in isolation, in the Salmonella enterica serovar Typhimurium FliF ortholog. We demonstrate that the periplasmic domain of FliF assembles into the MS ring, in the absence of the trans-membrane helices. We also report that the RBM2 and RBM3 domains oligomerize into ring structures, but not RBM1. Intriguingly, we observe that a construct encompassing RBM1 and RBM2 is monomeric, suggesting that RBM1 interacts with RBM2, and inhibits its oligomerization. However, this inhibition is lifted by the addition of RBM3. Collectively, this data suggest a mechanism for the controlled assembly of the MS ring.
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Affiliation(s)
- Giuseppina Mariano
- Randall Division of Cell and Molecular Biophysics, King's College London, London, United Kingdom.,Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, United Kingdom
| | - Raquel Faba-Rodriguez
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, United Kingdom
| | - Soi Bui
- Randall Division of Cell and Molecular Biophysics, King's College London, London, United Kingdom
| | - Weilong Zhao
- Randall Division of Cell and Molecular Biophysics, King's College London, London, United Kingdom
| | - James Ross
- Department of Biochemistry, University of British Columbia, Vancouver, BC, Canada
| | - Svetomir B Tzokov
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, United Kingdom
| | - Julien R C Bergeron
- Randall Division of Cell and Molecular Biophysics, King's College London, London, United Kingdom.,Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield, United Kingdom
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13
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Homma M, Nishikino T, Kojima S. Achievements in bacterial flagellar research with focus on Vibrio species. Microbiol Immunol 2021; 66:75-95. [PMID: 34842307 DOI: 10.1111/1348-0421.12954] [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] [Received: 09/13/2021] [Revised: 11/24/2021] [Accepted: 11/25/2021] [Indexed: 12/01/2022]
Abstract
In 1980's, the most genes involved in the bacterial flagellar function and formation had been isolated though many of their functions or roles were not clarified. Bacterial flagella are the primary locomotive organ and are not necessary for growing in vitro but are probably essential for living in natural condition and are involved in the pathogenicity. In vitro, the flagella-deficient strains can grow at rates similar to wild-type strains. More than 50 genes are responsible for flagellar function, and the flagellum is constructed by more than 20 structural proteins. The maintenance cost of flagellum is high as several genes are required for its development. The fact that it evolved as a motor organ even with such the high cost shows that the motility is indispensable to survive under the harsh environment of Earth. In this review, we focus on flagella-related research conducted by the authors for about 40 years and flagellar research focused on Vibrio spp. 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
| | | | - Seiji Kojima
- Division of Biological Science, Graduate School of Science, Nagoya University
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14
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Molecular and Cell Biological Analysis of SwrB in Bacillus subtilis. J Bacteriol 2021; 203:e0022721. [PMID: 34124944 DOI: 10.1128/jb.00227-21] [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: 11/20/2022] Open
Abstract
Swarming motility is flagellum-mediated movement over a solid surface, and Bacillus subtilis cells require an increase in flagellar density to swarm. SwrB is a protein of unknown function required for swarming that is necessary to increase the number of flagellar hooks but not basal bodies. Previous work suggested that SwrB activates flagellar type III secretion, but the mechanism by which it might perform this function is unknown. Here, we show that SwrB likely acts substoichiometrically as it localizes as puncta at the membrane in numbers fewer than those of flagellar basal bodies. Moreover, the action of SwrB is likely transient as puncta of SwrB were not dependent on the presence of the basal bodies and rarely colocalized with flagellar hooks. Random mutagenesis of the SwrB sequence found that a histidine within the transmembrane segment was conditionally required for activity and punctate localization. Finally, three hydrophobic residues that precede a cytoplasmic domain of poor conservation abolished SwrB activity when mutated and caused aberrant migration during electrophoresis. Our data are consistent with a model in which SwrB interacts with the flagellum, changes conformation to activate type III secretion, and departs. IMPORTANCE Type III secretion systems (T3SSs) are elaborate nanomachines that form the core of the bacterial flagellum and injectisome of pathogens. The machines not only secrete proteins like virulence factors but also secrete the structural components for their own assembly. Moreover, proper construction requires complex regulation to ensure that the parts are roughly secreted in the order in which they are assembled. Here, we explore a poorly understood activator of the flagellar T3SS activation in Bacillus subtilis called SwrB. To aid mechanistic understanding, we determine the rules for subcellular punctate localization, the topology with respect to the membrane, and critical residues required for SwrB function.
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15
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Kuhlen L, Johnson S, Cao J, Deme JC, Lea SM. Nonameric structures of the cytoplasmic domain of FlhA and SctV in the context of the full-length protein. PLoS One 2021; 16:e0252800. [PMID: 34143799 PMCID: PMC8213127 DOI: 10.1371/journal.pone.0252800] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2021] [Accepted: 05/21/2021] [Indexed: 12/18/2022] Open
Abstract
Type three secretion is the mechanism of protein secretion found in bacterial flagella and injectisomes. At its centre is the export apparatus (EA), a complex of five membrane proteins through which secretion substrates pass the inner membrane. While the complex formed by four of the EA proteins has been well characterised structurally, little is known about the structure of the membrane domain of the largest subunit, FlhA in flagella, SctV in injectisomes. Furthermore, the biologically relevant nonameric assembly of FlhA/SctV has been infrequently observed and differences in conformation of the cytoplasmic portion of FlhA/SctV between open and closed states have been suggested to reflect secretion system specific differences. FlhA has been shown to bind to chaperone-substrate complexes in an open state, but in previous assembled ring structures, SctV is in a closed state. Here, we identify FlhA and SctV homologues that can be recombinantly produced in the oligomeric state and study them using cryo-electron microscopy. The structures of the cytoplasmic domains from both FlhA and SctV are in the open state and we observe a conserved interaction between a short stretch of residues at the N-terminus of the cytoplasmic domain, known as FlhAL/SctVL, with a groove on the adjacent protomer’s cytoplasmic domain, which stabilises the nonameric ring assembly.
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Affiliation(s)
- Lucas Kuhlen
- Sir William Dunn School of Pathology, Oxford, United Kingdom
| | - Steven Johnson
- Sir William Dunn School of Pathology, Oxford, United Kingdom
- Center for Structural Biology, Center for Cancer Research, National Insititutes of Health, Frederick, MD, United States of America
| | - Jerry Cao
- Sir William Dunn School of Pathology, Oxford, United Kingdom
| | - Justin C. Deme
- Sir William Dunn School of Pathology, Oxford, United Kingdom
- Center for Structural Biology, Center for Cancer Research, National Insititutes of Health, Frederick, MD, United States of America
- Central Oxford Structural Molecular Imaging Centre, Oxford, United Kingdom
| | - Susan M. Lea
- Sir William Dunn School of Pathology, Oxford, United Kingdom
- Center for Structural Biology, Center for Cancer Research, National Insititutes of Health, Frederick, MD, United States of America
- Central Oxford Structural Molecular Imaging Centre, Oxford, United Kingdom
- * E-mail:
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16
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Kojima S, Kajino H, Hirano K, Inoue Y, Terashima H, Homma M. Role of the N- and C-terminal regions of FliF, the MS ring component in Vibrio flagellar basal body. J Bacteriol 2021; 203:JB.00009-21. [PMID: 33619151 PMCID: PMC8092156 DOI: 10.1128/jb.00009-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Accepted: 02/15/2021] [Indexed: 11/20/2022] Open
Abstract
The MS ring is a part of the flagellar basal body and formed by 34 subunits of FliF, which consists of a large periplasmic region and two transmembrane segments connected to the N- and C-terminal regions facing the cytoplasm. A cytoplasmic protein, FlhF, which determines the position and number of the basal body, supports MS ring formation in the membrane in Vibrio species. In this study, we constructed FliF deletion mutants that lack 30 or 50 residues from the N-terminus (ΔN30 and ΔN50), and 83 (ΔC83) or 110 residues (ΔC110) at the C-terminus. The N-terminal deletions were functional and conferred motility of Vibrio cells, whereas the C-terminal deletions were nonfunctional. The mutants were expressed in Escherichia coli to determine whether an MS ring could still be assembled. When co-expressing ΔN30FliF or ΔN50FliF with FlhF, fewer MS rings were observed than with the expression of wild-type FliF, in the MS ring fraction, suggesting that the N-terminus interacts with FlhF. MS ring formation is probably inefficient without FlhF. The deletion of the C-terminal cytoplasmic region did not affect the ability of FliF to form an MS ring because a similar number of MS rings were observed for ΔC83FliF as with wild-type FliF, although further deletion of the second transmembrane segment (ΔC110FliF) abolished it. These results suggest that the terminal regions of FliF have distinct roles; the N-terminal region for efficient MS ring formation and the C-terminal region for MS ring function. The second transmembrane segment is indispensable for MS ring assembly.ImportanceThe bacterial flagellum is a supramolecular architecture involved in cell motility. At the base of the flagella, a rotary motor that begins to construct an MS ring in the cytoplasmic membrane comprises 34 transmembrane proteins (FliF). Here, we investigated the roles of the N and C terminal regions of FliF, which are MS rings. Unexpectedly, the cytoplasmic regions of FliF are not indispensable for the formation of the MS ring, but the N-terminus appears to assist in ring formation through recruitment of FlhF, which is essential for flagellar formation. The C-terminus is essential for motor formation or function.
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Affiliation(s)
- Seiji Kojima
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan.
| | - Hiroki Kajino
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan
| | - Keiichi Hirano
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan
| | - Yuna Inoue
- 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
| | - Michio Homma
- 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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CwlQ Is Required for Swarming Motility but Not Flagellar Assembly in Bacillus subtilis. J Bacteriol 2021; 203:JB.00029-21. [PMID: 33649146 DOI: 10.1128/jb.00029-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Accepted: 02/22/2021] [Indexed: 11/20/2022] Open
Abstract
Lytic enzymes play an essential role in the remodeling of bacterial peptidoglycan (PG), an extracellular mesh-like structure that retains the membrane in the context of high internal osmotic pressure. Peptidoglycan must be unfailingly stable to preserve cell integrity, but must also be dynamically remodeled for the cell to grow, divide, and insert macromolecular machines. The flagellum is one such macromolecular machine that transits the PG, and flagellar insertion is aided by localized activity of a dedicated PG lyase in Gram-negative bacteria. To date, there is no known dedicated lyase in Gram-positive bacteria for the insertion of flagella. Here, we take a reverse-genetic candidate-gene approach and find that cells mutated for the lytic transglycosylase CwlQ exhibit a severe defect in flagellum-dependent swarming motility. We further show that CwlQ is expressed by the motility sigma factor SigD and is secreted by the type III secretion system housed inside the flagellum. Nonetheless, cells with mutations of CwlQ remain proficient for flagellar biosynthesis even when mutated in combination with four other lyases related to motility (LytC, LytD, LytF, and CwlO). The PG lyase (or lyases) essential for flagellar synthesis in B. subtilis, if any, remains unknown.IMPORTANCE Bacteria are surrounded by a wall of peptidoglycan and early work in Bacillus subtilis was the first to suggest that bacteria needed to enzymatically remodel the wall to permit insertion of the flagellum. No PG remodeling enzyme alone or in combination, however, has been found to be essential for flagellar assembly in B. subtilis Here, we take a reverse-genetic candidate-gene approach and find that the PG lytic transglycosylase CwlQ is required for swarming motility. Subsequent characterization determined that while CwlQ was coexpressed with motility genes and is secreted by the flagellar secretion apparatus, it was not required for flagellar synthesis. The PG lyase needed for flagellar assembly in B. subtilis remains unknown.
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18
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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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19
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Nishikino T, Kojima S, Homma M. [Flagellar related genes and functions in Vibrio]. Nihon Saikingaku Zasshi 2021; 75:195-214. [PMID: 33390367 DOI: 10.3412/jsb.75.195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Bacteria can move or swim by flagella. On the other hand, the motile ability is not necessary to live at all. In laboratory, the flagella-deficient strains can grow just like the wild-type strains. The flagellum is assembled from more than 20 structural proteins and there are more than 50 genes including the structural genes to regulate or support the flagellar formation. The cost to construct the flagellum is so expensive. The fact that it evolved as a motor organ means even at such the large cost shows that the flagellum is essential for survival in natural condition. In this review, we would like to focus on the flagella-related researches conducted by the authors and the flagellar research on Vibrio spp.
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Affiliation(s)
| | - Seiji Kojima
- Division of Biological Science, Graduate School of Science, Nagoya University
| | - Michio Homma
- Division of Biological Science, Graduate School of Science, Nagoya University
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20
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Milne-Davies B, Wimmi S, Diepold A. Adaptivity and dynamics in type III secretion systems. Mol Microbiol 2020; 115:395-411. [PMID: 33251695 DOI: 10.1111/mmi.14658] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 11/17/2020] [Accepted: 11/23/2020] [Indexed: 01/07/2023]
Abstract
The type III secretion system is the common core of two bacterial molecular machines: the flagellum and the injectisome. The flagellum is the most widely distributed prokaryotic locomotion device, whereas the injectisome is a syringe-like apparatus for inter-kingdom protein translocation, which is essential for virulence in important human pathogens. The successful concept of the type III secretion system has been modified for different bacterial needs. It can be adapted to changing conditions, and was found to be a dynamic complex constantly exchanging components. In this review, we highlight the flexibility, adaptivity, and dynamic nature of the type III secretion system.
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Affiliation(s)
- Bailey Milne-Davies
- Department of Ecophysiology, Max-Planck-Institute for Terrestrial Microbiology, Marburg, Germany
| | - Stephan Wimmi
- Department of Ecophysiology, Max-Planck-Institute for Terrestrial Microbiology, Marburg, Germany
| | - Andreas Diepold
- Department of Ecophysiology, Max-Planck-Institute for Terrestrial Microbiology, Marburg, Germany
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21
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Abstract
The bacterial flagellar motor is the most complex structure in the bacterial cell, driving the ion-driven rotation of the helical flagellum. The ordered expression of the regulon and the assembly of the series of interacting protein rings, spanning the inner and outer membranes to form the ∼45–50-nm protein complex, have made investigation of the structure and mechanism a major challenge since its recognition as a rotating nanomachine about 40 years ago. Painstaking molecular genetics, biochemistry, and electron microscopy revealed a tiny electric motor spinning in the bacterial membrane. Over the last decade, new single-molecule and in vivo biophysical methods have allowed investigation of the stability of this and other large protein complexes, working in their natural environment inside live cells. This has revealed that in the bacterial flagellar motor, protein molecules in both the rotor and stator exchange with freely circulating pools of spares on a timescale of minutes, even while motors are continuously rotating. This constant exchange has allowed the evolution of modified components allowing bacteria to keep swimming as the viscosity or the ion composition of the outside environment changes.
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Affiliation(s)
- Judith P. Armitage
- Department of Biochemistry, University of Oxford, OX1 3QU, United Kingdom
| | - Richard M. Berry
- Department of Physics, University of Oxford, OX1 3PU, United Kingdom
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22
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Rhee KY, Chawla R, Lele PP. Protein expression-independent response of intensity-based pH-sensitive fluorophores in Escherichia coli. PLoS One 2020; 15:e0234849. [PMID: 32555627 PMCID: PMC7302705 DOI: 10.1371/journal.pone.0234849] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 06/02/2020] [Indexed: 12/02/2022] Open
Abstract
Fluorescent proteins that modulate their emission intensities when protonated serve as excellent probes of the cytosolic pH. Since the total fluorescence output fluctuates significantly due to variations in the fluorophore levels in cells, eliminating the dependence of the signal on protein concentration is crucial. This is typically accomplished with the aid of ratiometric fluorescent proteins such as pHluorin. However, pHluorin is excited by blue light, which can complicate pH measurements by adversely impacting bacterial physiology. Here, we characterized the response of intensity-based, pH-sensitive fluorescent proteins that excite at longer wavelengths where the blue light effect is diminished. The pH-response was interpreted in terms of an analytical model that assumed two emission states for each fluorophore: a low intensity protonated state and a high intensity deprotonated state. The model suggested a scaling to eliminate the dependence of the signal on the expression levels as well as on the illumination and photon-detection settings. Experiments successfully confirmed the scaling predictions. Thus, the internal pH can be readily determined with intensity-based fluorophores with appropriate calibrations irrespective of the fluorophore concentration and the signal acquisition setup. The framework developed in this work improves the robustness of intensity-based fluorophores for internal pH measurements in E. coli, potentially extending their applications.
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Affiliation(s)
- Kathy Y. Rhee
- Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, Texas, United States of America
| | - Ravi Chawla
- Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, Texas, United States of America
| | - Pushkar P. Lele
- Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, Texas, United States of America
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23
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Terashima H, Hirano K, Inoue Y, Tokano T, Kawamoto A, Kato T, Yamaguchi E, Namba K, Uchihashi T, Kojima S, Homma M. Assembly mechanism of a supramolecular MS-ring complex to initiate bacterial flagellar biogenesis in Vibrio species. J Bacteriol 2020; 202:JB.00236-20. [PMID: 32482724 PMCID: PMC8404704 DOI: 10.1128/jb.00236-20] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Accepted: 05/28/2020] [Indexed: 12/22/2022] Open
Abstract
The bacterial flagellum is an organelle responsible for motility and has a rotary motor comprising the rotor and the stator. Flagellar biogenesis is initiated by the assembly of the MS-ring, a supramolecular complex embedded in the cytoplasmic membrane. The MS-ring consists of a few dozen copies of the transmembrane FliF protein, and is an essential core structure which is a part of the rotor. The number and location of the flagella are controlled by the FlhF and FlhG proteins in some species. However, there is no clarity on the factors initiating MS-ring assembly, and contribution of FlhF/FlhG to this process. Here, we show that FlhF and a C-ring component FliG facilitate Vibrio MS-ring formation. When Vibrio FliF alone was expressed in Escherichia coli cells, MS-ring formation rarely occurred, indicating the requirement of other factors for MS-ring assembly. Consequently, we investigated if FlhF aided FliF in MS-ring assembly. We found that FlhF allowed GFP-fused FliF to localize at the cell pole in a Vibrio cell, suggesting that it increases local concentration of FliF at the pole. When FliF was co-expressed with FlhF in E. coli cells, the MS-ring was effectively formed, indicating that FlhF somehow contributes to MS-ring formation. The isolated MS-ring structure was similar to the MS-ring formed by Salmonella FliF. Interestingly, FliG facilitates MS-ring formation, suggesting that FliF and FliG assist in each other's assembly into the MS-ring and C-ring. This study aids in understanding the mechanism behind MS-ring assembly using appropriate spatial/temporal regulations.Importance Flagellar formation is initiated by the assembly of the FliF protein into the MS-ring complex, embedded in the cytoplasmic membrane. The appropriate spatial/temporal control of MS-ring formation is important for the morphogenesis of the bacterial flagellum. Here, we focus on the assembly mechanism of Vibrio FliF into the MS-ring. FlhF, a positive regulator of the number and location of flagella, recruits the FliF molecules at the cell pole and facilitates MS-ring formation. FliG also facilitates MS-ring formation. Our study showed that these factors control flagellar biogenesis in Vibrio, by initiating the MS-ring assembly. Furthermore, it also implies that flagellar biogenesis is a sophisticated system linked with the expression of certain genes, protein localization and a supramolecular complex assembly.
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Affiliation(s)
- Hiroyuki Terashima
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan
| | - Keiichi Hirano
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan
| | - Yuna Inoue
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan
| | - Takaya Tokano
- Division of Material Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan
| | - Akihiro Kawamoto
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Takayuki Kato
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
- JEOL YOKOGUSHI Research Alliance Laboratories, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Erika Yamaguchi
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan
| | - Keiichi Namba
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
- JEOL YOKOGUSHI Research Alliance Laboratories, Osaka University, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
- RIKEN Spring-8 Center and Center for Biosystems Dynamic Research, 1-3 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Takayuki Uchihashi
- Division of Material Science, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan
- Exploratory Research Center on Life and Living Systems (ExCELLS), National Institutes of Natural Sciences, Aichi 444-8787, 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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24
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Abstract
Following the success of and the high demand for recombinant protein-based therapeutics during the last 25 years, the pharmaceutical industry has invested significantly in the development of novel treatments based on biologics. Mammalian cells are the major production systems for these complex biopharmaceuticals, with Chinese hamster ovary (CHO) cell lines as the most important players. Over the years, various engineering strategies and modeling approaches have been used to improve microbial production platforms, such as bacteria and yeasts, as well as to create pre-optimized chassis host strains. However, the complexity of mammalian cells curtailed the optimization of these host cells by metabolic engineering. Most of the improvements of titer and productivity were achieved by media optimization and large-scale screening of producer clones. The advances made in recent years now open the door to again consider the potential application of systems biology approaches and metabolic engineering also to CHO. The availability of a reference genome sequence, genome-scale metabolic models and the growing number of various “omics” datasets can help overcome the complexity of CHO cells and support design strategies to boost their production performance. Modular design approaches applied to engineer industrially relevant cell lines have evolved to reduce the time and effort needed for the generation of new producer cells and to allow the achievement of desired product titers and quality. Nevertheless, important steps to enable the design of a chassis platform similar to those in use in the microbial world are still missing. In this review, we highlight the importance of mammalian cellular platforms for the production of biopharmaceuticals and compare them to microbial platforms, with an emphasis on describing novel approaches and discussing still open questions that need to be resolved to reach the objective of designing enhanced modular chassis CHO cell lines.
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25
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Tn FLX: a Third-Generation mariner-Based Transposon System for Bacillus subtilis. Appl Environ Microbiol 2020; 86:AEM.02893-19. [PMID: 32169936 DOI: 10.1128/aem.02893-19] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 01/26/2020] [Indexed: 01/05/2023] Open
Abstract
Random transposon mutagenesis is a powerful and unbiased genetic approach to answer fundamental biological questions. Here, we introduce an improved mariner-based transposon system with enhanced stability during propagation and versatile applications in mutagenesis. We used a low-copy-number plasmid as a transposon delivery vehicle, which affords a lower frequency of unintended recombination during vector construction and propagation in Escherichia coli We generated a variety of transposons allowing for gene disruption or artificial overexpression, each in combination with one of four different antibiotic resistance markers. In addition, we provide transposons that will report gene/protein expression due to transcriptional or translational coupling. We believe that the TnFLX system will help enhance the flexibility of future transposon modification and application in Bacillus and other organisms.IMPORTANCE The stability of transposase-encoding vectors during cloning and propagation is crucial for the reliable application of transposons. Here, we increased the stability of the mariner delivery vehicle in E. coli Moreover, the TnFLX transposon system will improve the application of forward genetic methods with an increased number of antibiotic resistance markers and the ability to generate unbiased green fluorescent protein (GFP) fusions to report on protein translation and subcellular localization.
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26
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Bacterial flagellar motor PL-ring disassembly subcomplexes are widespread and ancient. Proc Natl Acad Sci U S A 2020; 117:8941-8947. [PMID: 32241888 PMCID: PMC7183148 DOI: 10.1073/pnas.1916935117] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
In order to understand the evolution of complex biological machines like the bacterial flagellar motor, it is crucial to know what each component does and when it arose. Here, we show that a subcomplex of the motor thought to act as a bushing for the spinning motor likely also serves another function—it plugs the hole in the outer membrane left when the flagellum disassembles. Moreover, this component and function is ancient, since it appears in diverse phyla without evidence of recent gene transfer. The bacterial flagellum is an amazing nanomachine. Understanding how such complex structures arose is crucial to our understanding of cellular evolution. We and others recently reported that in several Gammaproteobacterial species, a relic subcomplex comprising the decorated P and L rings persists in the outer membrane after flagellum disassembly. Imaging nine additional species with cryo-electron tomography, here, we show that this subcomplex persists after flagellum disassembly in other phyla as well. Bioinformatic analyses fail to show evidence of any recent horizontal transfers of the P- and L-ring genes, suggesting that this subcomplex and its persistence is an ancient and conserved feature of the flagellar motor. We hypothesize that one function of the P and L rings is to seal the outer membrane after motor disassembly.
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Beeby M, Ferreira JL, Tripp P, Albers SV, Mitchell DR. Propulsive nanomachines: the convergent evolution of archaella, flagella and cilia. FEMS Microbiol Rev 2020; 44:253-304. [DOI: 10.1093/femsre/fuaa006] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Accepted: 03/06/2020] [Indexed: 02/06/2023] Open
Abstract
ABSTRACT
Echoing the repeated convergent evolution of flight and vision in large eukaryotes, propulsive swimming motility has evolved independently in microbes in each of the three domains of life. Filamentous appendages – archaella in Archaea, flagella in Bacteria and cilia in Eukaryotes – wave, whip or rotate to propel microbes, overcoming diffusion and enabling colonization of new environments. The implementations of the three propulsive nanomachines are distinct, however: archaella and flagella rotate, while cilia beat or wave; flagella and cilia assemble at their tips, while archaella assemble at their base; archaella and cilia use ATP for motility, while flagella use ion-motive force. These underlying differences reflect the tinkering required to evolve a molecular machine, in which pre-existing machines in the appropriate contexts were iteratively co-opted for new functions and whose origins are reflected in their resultant mechanisms. Contemporary homologies suggest that archaella evolved from a non-rotary pilus, flagella from a non-rotary appendage or secretion system, and cilia from a passive sensory structure. Here, we review the structure, assembly, mechanism and homologies of the three distinct solutions as a foundation to better understand how propulsive nanomachines evolved three times independently and to highlight principles of molecular evolution.
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Affiliation(s)
- Morgan Beeby
- Department of Life Sciences, Frankland Road, Imperial College of London, London, SW7 2AZ, UK
| | - Josie L Ferreira
- Department of Life Sciences, Frankland Road, Imperial College of London, London, SW7 2AZ, UK
| | - Patrick Tripp
- Molecular Biology of Archaea, Institute of Biology, University of Freiburg, Schaenzlestrasse 1, 79211 Freiburg, Germany
| | - Sonja-Verena Albers
- Molecular Biology of Archaea, Institute of Biology, University of Freiburg, Schaenzlestrasse 1, 79211 Freiburg, Germany
| | - David R Mitchell
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, 750 E. Adams St., Syracuse, NY 13210, USA
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Drehkopf S, Otten C, Hausner J, Seifert T, Büttner D. HrpB7 from
Xanthomonas campestris
pv.
vesicatoria
is an essential component of the type III secretion system and shares features of HrpO/FliJ/YscO family members. Cell Microbiol 2020; 22:e13160. [DOI: 10.1111/cmi.13160] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2019] [Revised: 12/16/2019] [Accepted: 12/24/2019] [Indexed: 12/22/2022]
Affiliation(s)
- Sabine Drehkopf
- Department of Genetics, Institute of BiologyMartin Luther University Halle‐Wittenberg Halle (Saale) Germany
| | - Christian Otten
- Department of Genetics, Institute of BiologyMartin Luther University Halle‐Wittenberg Halle (Saale) Germany
| | - Jens Hausner
- Department of Genetics, Institute of BiologyMartin Luther University Halle‐Wittenberg Halle (Saale) Germany
| | - Tanja Seifert
- Department of Genetics, Institute of BiologyMartin Luther University Halle‐Wittenberg Halle (Saale) Germany
| | - Daniela Büttner
- Department of Genetics, Institute of BiologyMartin Luther University Halle‐Wittenberg Halle (Saale) Germany
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A Polar Flagellar Transcriptional Program Mediated by Diverse Two-Component Signal Transduction Systems and Basal Flagellar Proteins Is Broadly Conserved in Polar Flagellates. mBio 2020; 11:mBio.03107-19. [PMID: 32127455 PMCID: PMC7064773 DOI: 10.1128/mbio.03107-19] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Relative to peritrichous bacteria, polar flagellates possess regulatory systems that order flagellar gene transcription differently and produce flagella in specific numbers only at poles. How transcriptional and flagellar biogenesis regulatory systems are interlinked to promote the correct synthesis of polar flagella in diverse species has largely been unexplored. We found evidence for many Gram-negative polar flagellates encoding two-component signal transduction systems with activity linked to the formation of flagellar type III secretion systems to enable production of flagellar rod and hook proteins at a discrete, subsequent stage during flagellar assembly. This polar flagellar transcriptional program assists, in some manner, the FlhF/FlhG flagellar biogenesis regulatory system, which forms specific flagellation patterns in polar flagellates in maintaining flagellation and motility when activity of FlhF or FlhG might be altered. Our work provides insight into the multiple regulatory processes required for polar flagellation. Bacterial flagella are rotating nanomachines required for motility. Flagellar gene expression and protein secretion are coordinated for efficient flagellar biogenesis. Polar flagellates, unlike peritrichous bacteria, commonly order flagellar rod and hook gene transcription as a separate step after production of the MS ring, C ring, and flagellar type III secretion system (fT3SS) core proteins that form a competent fT3SS. Conserved regulatory mechanisms in diverse polar flagellates to create this polar flagellar transcriptional program have not been thoroughly assimilated. Using in silico and genetic analyses and our previous findings in Campylobacter jejuni as a foundation, we observed a large subset of Gram-negative bacteria with the FlhF/FlhG regulatory system for polar flagellation to possess flagellum-associated two-component signal transduction systems (TCSs). We present data supporting a general theme in polar flagellates whereby MS ring, rotor, and fT3SS proteins contribute to a regulatory checkpoint during polar flagellar biogenesis. We demonstrate that Vibrio cholerae and Pseudomonas aeruginosa require the formation of this regulatory checkpoint for the TCSs to directly activate subsequent rod and hook gene transcription, which are hallmarks of the polar flagellar transcriptional program. By reprogramming transcription in V. cholerae to more closely follow the peritrichous flagellar transcriptional program, we discovered a link between the polar flagellar transcription program and the activity of FlhF/FlhG flagellar biogenesis regulators in which the transcriptional program allows polar flagellates to continue to produce flagella for motility when FlhF or FlhG activity may be altered. Our findings integrate flagellar transcriptional and biogenesis regulatory processes involved in polar flagellation in many species.
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Kim JM, Garcia-Alcala M, Balleza E, Cluzel P. Stochastic transcriptional pulses orchestrate flagellar biosynthesis in Escherichia coli. SCIENCE ADVANCES 2020; 6:eaax0947. [PMID: 32076637 PMCID: PMC7002133 DOI: 10.1126/sciadv.aax0947] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Accepted: 11/22/2019] [Indexed: 05/28/2023]
Abstract
The classic picture of flagellum biosynthesis in Escherichia coli, inferred from population measurements, depicts a deterministic program where promoters are sequentially up-regulated and are maintained steadily active throughout exponential growth. However, complex regulatory dynamics at the single-cell level can be masked by bulk measurements. Here, we discover that in individual E. coli cells, flagellar promoters are stochastically activated in pulses. These pulses are coordinated within specific classes of promoters and comprise "on" and "off" states, each of which can span multiple generations. We demonstrate that in this pulsing program, the regulatory logic of flagellar assembly dictates which promoters skip pulses. Surprisingly, pulses do not require specific transcriptional or translational regulation of the flagellar master regulator, FlhDC, but instead appears to be essentially governed by an autonomous posttranslational circuit. Our results suggest that even topologically simple transcriptional networks can generate unexpectedly rich temporal dynamics and phenotypic heterogeneities.
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Affiliation(s)
- J. Mark Kim
- Department of Molecular and Cellular Biology, Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
| | - Mayra Garcia-Alcala
- Department of Molecular and Cellular Biology, Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
- Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos 62210, México
| | - Enrique Balleza
- Department of Molecular and Cellular Biology, Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
| | - Philippe Cluzel
- Department of Molecular and Cellular Biology, Harvard John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
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Lee JH, Ancona V, Chatnaparat T, Yang HW, Zhao Y. The RNA-Binding Protein CsrA Controls Virulence in Erwinia amylovora by Regulating RelA, RcsB, and FlhD at the Posttranscriptional Level. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2019; 32:1448-1459. [PMID: 31140921 DOI: 10.1094/mpmi-03-19-0077-r] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
CsrA, an RNA-binding protein, binds to target transcripts and alters their translation or stability. In Erwinia amylovora, CsrA positively regulates the expression of type III secretion system (T3SS), exopolysaccharide amylovoran, and motility. In this study, the global effect of CsrA and its noncoding small RNA (ncsRNA) csrB in E. amylovora was determined by RNA-seq, and potential molecular mechanisms of CsrA-dependent virulence regulation were examined. Transcriptomic analyses under the T3SS-inducing condition revealed that mutation in the csrA gene led to differential expression of more than 20% of genes in the genome. Among them, T3SS genes and those required for cell growth and viability were significantly downregulated. On the other hand, the csrB mutant exhibited significant upregulation of most major virulence genes, suggesting an antagonistic effect of csrB on CsrA targets. Direct interaction between CsrA protein and csrB was further confirmed through the RNA electrophoretic mobility shift assay (REMSA). However, no direct interaction between CsrA and hrpL and hrpS transcripts was detected, suggesting that HrpL and HrpS are not targets of CsrA, whereas three CsrA targets (relA, rcsB, and flhD) were identified and confirmed by REMSA, site-directed mutagenesis, and LacZ reporter gene assays. These findings might partially explain how CsrA positively controls E. amylovora virulence by targeting major regulators at the posttranscriptional level.
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Affiliation(s)
- Jae Hoon Lee
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801, U.S.A
| | - Veronica Ancona
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801, U.S.A
| | - Tiyakhon Chatnaparat
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801, U.S.A
| | - Ho-Wen Yang
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801, U.S.A
| | - Youfu Zhao
- Department of Crop Sciences, University of Illinois at Urbana-Champaign, Urbana, IL 61801, U.S.A
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32
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Singh N, Wagner S. Investigating the assembly of the bacterial type III secretion system injectisome by in vivo photocrosslinking. Int J Med Microbiol 2019; 309:151331. [DOI: 10.1016/j.ijmm.2019.151331] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2019] [Revised: 07/09/2019] [Accepted: 07/12/2019] [Indexed: 12/11/2022] Open
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33
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Koganitsky A, Tworowski D, Dadosh T, Cecchini G, Eisenbach M. A Mechanism of Modulating the Direction of Flagellar Rotation in Bacteria by Fumarate and Fumarate Reductase. J Mol Biol 2019; 431:3662-3676. [PMID: 31412261 DOI: 10.1016/j.jmb.2019.08.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2019] [Revised: 07/31/2019] [Accepted: 08/01/2019] [Indexed: 02/04/2023]
Abstract
Fumarate, an electron acceptor in anaerobic respiration of Escherichia coli, has an additional function of assisting the flagellar motor to shift from counterclockwise to clockwise rotation, with a consequent modulation of the bacterial swimming behavior. Fumarate transmits its effect to the motor via the fumarate reductase complex (FrdABCD), shown to bind to FliG-one of the motor's switch proteins. How binding of the FrdABCD respiratory enzyme to FliG enhances clockwise rotation and how fumarate is involved in this activity have remained puzzling. Here we show that the FrdA subunit in the presence of fumarate is sufficient for binding to FliG and for clockwise enhancement. We further demonstrate by in vitro binding assays and super-resolution microscopy in vivo that the mechanism by which fumarate-occupied FrdA enhances clockwise rotation involves its preferential binding to the clockwise state of FliG (FliGcw). Continuum electrostatics combined with docking analysis and conformational sampling endorsed the experimental conclusions and suggested that the FrdA-FliGcw interaction is driven by the positive electrostatic potential generated by FrdA and the negatively charged areas of FliG. They further demonstrated that fumarate changes FrdA's conformation to one that can bind to FliGcw. These findings also show that the reason for the failure of the succinate dehydrogenase flavoprotein SdhA (an almost-identical analog of FrdA shown to bind to FliG equally well) to enhance clockwise rotation is that it has no binding preference for FliGcw. We suggest that this mechanism is physiologically important as it can modulate the magnitude of ΔG0 between the clockwise and counterclockwise states of the motor to tune the motor to the growth conditions of the bacteria.
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Affiliation(s)
- Anna Koganitsky
- Department of Biomolecular Sciences, The Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Dmitry Tworowski
- Department of Structural Biology, The Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Tali Dadosh
- Department of Chemical Research Support, The Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Gary Cecchini
- Molecular Biology Division, San Francisco VA Health Care System, San Francisco, CA 94121, USA; Department of Biochemistry & Biophysics, University of California, San Francisco, CA 94158, USA
| | - Michael Eisenbach
- Department of Biomolecular Sciences, The Weizmann Institute of Science, 7610001 Rehovot, Israel.
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34
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Kaplan M, Subramanian P, Ghosal D, Oikonomou CM, Pirbadian S, Starwalt‐Lee R, Mageswaran SK, Ortega DR, Gralnick JA, El‐Naggar MY, Jensen GJ. In situ imaging of the bacterial flagellar motor disassembly and assembly processes. EMBO J 2019; 38:e100957. [PMID: 31304634 PMCID: PMC6627242 DOI: 10.15252/embj.2018100957] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Revised: 04/11/2019] [Accepted: 04/18/2019] [Indexed: 11/09/2022] Open
Abstract
The self-assembly of cellular macromolecular machines such as the bacterial flagellar motor requires the spatio-temporal synchronization of gene expression with proper protein localization and association of dozens of protein components. In Salmonella and Escherichia coli, a sequential, outward assembly mechanism has been proposed for the flagellar motor starting from the inner membrane, with the addition of each new component stabilizing the previous one. However, very little is known about flagellar disassembly. Here, using electron cryo-tomography and sub-tomogram averaging of intact Legionella pneumophila, Pseudomonas aeruginosa, and Shewanella oneidensis cells, we study flagellar motor disassembly and assembly in situ. We first show that motor disassembly results in stable outer membrane-embedded sub-complexes. These sub-complexes consist of the periplasmic embellished P- and L-rings, and bend the membrane inward while it remains apparently sealed. Additionally, we also observe various intermediates of the assembly process including an inner-membrane sub-complex consisting of the C-ring, MS-ring, and export apparatus. Finally, we show that the L-ring is responsible for reshaping the outer membrane, a crucial step in the flagellar assembly process.
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Affiliation(s)
- Mohammed Kaplan
- Division of Biology and Biological EngineeringCalifornia Institute of TechnologyPasadenaCAUSA
| | - Poorna Subramanian
- Division of Biology and Biological EngineeringCalifornia Institute of TechnologyPasadenaCAUSA
| | - Debnath Ghosal
- Division of Biology and Biological EngineeringCalifornia Institute of TechnologyPasadenaCAUSA
| | - Catherine M Oikonomou
- Division of Biology and Biological EngineeringCalifornia Institute of TechnologyPasadenaCAUSA
| | - Sahand Pirbadian
- Department of Physics and Astronomy, Biological Sciences, and ChemistryUniversity of Southern CaliforniaLos AngelesCAUSA
| | - Ruth Starwalt‐Lee
- BioTechnology InstituteUniversity of Minnesota – Twin CitiesSt. PaulMNUSA
| | | | - Davi R Ortega
- Division of Biology and Biological EngineeringCalifornia Institute of TechnologyPasadenaCAUSA
| | - Jeffrey A Gralnick
- BioTechnology InstituteUniversity of Minnesota – Twin CitiesSt. PaulMNUSA
- Department of Plant and Microbial BiologyUniversity of Minnesota – Twin CitiesSt. PaulMNUSA
| | - Mohamed Y El‐Naggar
- Department of Physics and Astronomy, Biological Sciences, and ChemistryUniversity of Southern CaliforniaLos AngelesCAUSA
| | - Grant J Jensen
- Division of Biology and Biological EngineeringCalifornia Institute of TechnologyPasadenaCAUSA
- Howard Hughes Medical InstituteCalifornia Institute of TechnologyPasadenaCAUSA
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35
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Rudenko I, Ni B, Glatter T, Sourjik V. Inefficient Secretion of Anti-sigma Factor FlgM Inhibits Bacterial Motility at High Temperature. iScience 2019; 16:145-154. [PMID: 31170626 PMCID: PMC6551532 DOI: 10.1016/j.isci.2019.05.022] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2019] [Revised: 04/01/2019] [Accepted: 05/15/2019] [Indexed: 12/03/2022] Open
Abstract
Temperature is one of the key cues that enable microorganisms to adjust their physiology in response to environmental changes. Here we show that motility is the major cellular function of Escherichia coli that is differentially regulated between growth at normal host temperature of 37°C and the febrile temperature of 42°C. Expression of both class II and class III flagellar genes is reduced at 42°C because of lowered level of the upstream activator FlhD. Class III genes are additionally repressed because of the destabilization and malfunction of secretion apparatus at high temperature, which prevents secretion of the anti-sigma factor FlgM. This mechanism of repression apparently accelerates loss of motility at 42°C. We hypothesize that E. coli perceives high temperature as a sign of inflammation, downregulating flagella to escape detection by the immune system of the host. Secretion-dependent coupling of gene expression to the environmental temperature is likely common among many bacteria. E. coli motility is tightly turned off at febrile temperature (42°C) Repression of motility is achieved at two levels of hierarchical gene regulation Lowered FlhD level reduces expression of all flagellar genes Impaired FlgM secretion tightens repression of class III genes
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Affiliation(s)
- Iaroslav Rudenko
- Department of Systems and Synthetic Microbiology, Max Planck Institute for Terrestrial Microbiology & LOEWE Center for Synthetic Microbiology (SYNMIKRO), Marburg 35043, Germany
| | - Bin Ni
- Department of Systems and Synthetic Microbiology, Max Planck Institute for Terrestrial Microbiology & LOEWE Center for Synthetic Microbiology (SYNMIKRO), Marburg 35043, Germany
| | - Timo Glatter
- Core Facility for Mass Spectrometry & Proteomics, Max Planck Institute for Terrestrial Microbiology, Marburg 35043, Germany
| | - Victor Sourjik
- Department of Systems and Synthetic Microbiology, Max Planck Institute for Terrestrial Microbiology & LOEWE Center for Synthetic Microbiology (SYNMIKRO), Marburg 35043, Germany.
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36
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Hausner J, Jordan M, Otten C, Marillonnet S, Büttner D. Modular Cloning of the Type III Secretion Gene Cluster from the Plant-Pathogenic Bacterium Xanthomonas euvesicatoria. ACS Synth Biol 2019; 8:532-547. [PMID: 30694661 DOI: 10.1021/acssynbio.8b00434] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Type III secretion (T3S) systems are essential pathogenicity factors of most Gram-negative bacteria and translocate effector proteins into plant or animal cells. T3S systems can, therefore, be used as tools for protein delivery into eukaryotic cells, for instance after transfer of the T3S gene cluster into nonpathogenic recipient strains. Here, we report the modular cloning of the T3S gene cluster from the plant-pathogenic bacterium Xanthomonas euvesicatoria. The resulting multigene construct encoded a functional T3S system and delivered effector proteins into plant cells. The modular design of the T3S gene cluster allowed the efficient replacement and rearrangement of single genes or operons and the insertion of reporter genes for functional studies. In the present study, we used the modular T3S system to analyze the assembly of a fluorescent fusion of the predicted cytoplasmic ring protein HrcQ. Our studies demonstrate the use of the modular T3S gene cluster for functional analyses and mutant approaches in X. euvesicatoria. A potential application of the modular T3S system as protein delivery tool is discussed.
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Affiliation(s)
- Jens Hausner
- Institute of Biology, Department of Genetics, Martin Luther University Halle-Wittenberg, Weinbergweg 10, 06120 Halle, Saale, Germany
| | - Michael Jordan
- Institute of Biology, Department of Genetics, Martin Luther University Halle-Wittenberg, Weinbergweg 10, 06120 Halle, Saale, Germany
| | - Christian Otten
- Institute of Biology, Department of Genetics, Martin Luther University Halle-Wittenberg, Weinbergweg 10, 06120 Halle, Saale, Germany
| | | | - Daniela Büttner
- Institute of Biology, Department of Genetics, Martin Luther University Halle-Wittenberg, Weinbergweg 10, 06120 Halle, Saale, Germany
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37
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Zhang J, Wang X, Suo X, Liu X, Liu B, Yuan M, Wang G, Liang C, Shi H. Cellular Response of Escherichia coli to Photocatalysis: Flagellar Assembly Variation and Beyond. ACS NANO 2019; 13:2004-2014. [PMID: 30721027 DOI: 10.1021/acsnano.8b08475] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Bacterial cells can be inactivated by external reactive oxygen species (ROS) produced by semiconductor photocatalysis. However, little is known about cellular responses to photocatalysis. For a better understanding of this issue, one strain of Escherichia coli ( E. coli, hereafter named as MT), which has an increased ability to metabolize carbon sources, was screened out from the wild-type (WT) E. coli K12 by repeated exposure to photocatalysis with palladium oxide modified nitrogen-doped titanium dioxide. In this study, transcriptome sequencing of the WT and MT strains that were exposed or unexposed to photocatalysis were carried out. Cellular responses to photocatalysis were inferred from the functions of genes whose transcripts were either increased or decreased. Upregulation of expression of bacterial flagellar assembly genes used for chemotaxis was detected in cells exposed to semilethal photocatalytic conditions of the WT E. coli. Increased capability to degrade superoxide radicals and decreased bacterial flagellar assembly and chemotaxis were observed in MT E. coli compared to WT cells. We conclude that the differences in motility and intracellular ROS between MT and WT are directly related to survivability of E. coli during exposure to photodisinfection.
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Affiliation(s)
- Jingtao Zhang
- Collaborative Innovation Centre of Food Production and Safety, Henan Key Laboratory of Cold Chain Food Quality and Safety Control, School of Food and Bioengineering , Zhengzhou University of Light Industry , Zhengzhou 450002 , China
| | - Xueying Wang
- Collaborative Innovation Centre of Food Production and Safety, Henan Key Laboratory of Cold Chain Food Quality and Safety Control, School of Food and Bioengineering , Zhengzhou University of Light Industry , Zhengzhou 450002 , China
| | - Xinying Suo
- Collaborative Innovation Centre of Food Production and Safety, Henan Key Laboratory of Cold Chain Food Quality and Safety Control, School of Food and Bioengineering , Zhengzhou University of Light Industry , Zhengzhou 450002 , China
| | - Xing Liu
- Collaborative Innovation Centre of Food Production and Safety, Henan Key Laboratory of Cold Chain Food Quality and Safety Control, School of Food and Bioengineering , Zhengzhou University of Light Industry , Zhengzhou 450002 , China
| | - Bingkun Liu
- School of Material and Chemical Engineering , Zhengzhou University of Light Industry , Zhengzhou 450002 , China
| | - Mingming Yuan
- Collaborative Innovation Centre of Food Production and Safety, Henan Key Laboratory of Cold Chain Food Quality and Safety Control, School of Food and Bioengineering , Zhengzhou University of Light Industry , Zhengzhou 450002 , China
| | - Guanglu Wang
- Collaborative Innovation Centre of Food Production and Safety, Henan Key Laboratory of Cold Chain Food Quality and Safety Control, School of Food and Bioengineering , Zhengzhou University of Light Industry , Zhengzhou 450002 , China
| | - Chengzhen Liang
- Biotechnology Research Institute , Chinese Academy of Agricultural Sciences , Beijing 100081 , China
| | - Hengzhen Shi
- School of Material and Chemical Engineering , Zhengzhou University of Light Industry , Zhengzhou 450002 , China
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38
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Diepold A. Assembly and Post-assembly Turnover and Dynamics in the Type III Secretion System. Curr Top Microbiol Immunol 2019; 427:35-66. [PMID: 31218503 DOI: 10.1007/82_2019_164] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The type III secretion system (T3SS) is one of the largest transmembrane complexes in bacteria, comprising several intricately linked and embedded substructures. The assembly of this nanomachine is a hierarchical process which is regulated and controlled by internal and external cues at several critical points. Recently, it has become obvious that the assembly of the T3SS is not a unidirectional and deterministic process, but that parts of the T3SS constantly exchange or rearrange. This article aims to give an overview on the assembly and post-assembly dynamics of the T3SS, with a focus on emerging general concepts and adaptations of the general assembly pathway.
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Affiliation(s)
- Andreas Diepold
- Department of Ecophysiology, Max Planck Institute for Terrestrial Microbiology, Karl-von-Frisch-Straße 10, 35043, Marburg, Germany.
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39
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Molecular Organization and Assembly of the Export Apparatus of Flagellar Type III Secretion Systems. Curr Top Microbiol Immunol 2019; 427:91-107. [PMID: 31172377 DOI: 10.1007/82_2019_170] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
The bacterial flagellum is a supramolecular motility machine consisting of the basal body, the hook, and the filament. For construction of the flagellum beyond the cellular membranes, a type III protein export apparatus uses ATP and proton-motive force (PMF) across the cytoplasmic membrane as the energy sources to transport flagellar component proteins from the cytoplasm to the distal end of the growing flagellar structure. The protein export apparatus consists of a PMF-driven transmembrane export gate complex and a cytoplasmic ATPase complex. In addition, the basal body C ring acts as a sorting platform for the cytoplasmic ATPase complex that efficiently brings export substrates and type III export chaperone-substrate complexes from the cytoplasm to the export gate complex. In this book chapter, we will summarize our current understanding of molecular organization and assembly of the flagellar type III protein export apparatus.
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Tusk SE, Delalez NJ, Berry RM. Subunit Exchange in Protein Complexes. J Mol Biol 2018; 430:4557-4579. [DOI: 10.1016/j.jmb.2018.06.039] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2018] [Revised: 06/21/2018] [Accepted: 06/21/2018] [Indexed: 01/09/2023]
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Ford KM, Antani JD, Nagarajan A, Johnson MM, Lele PP. Switching and Torque Generation in Swarming E. coli. Front Microbiol 2018; 9:2197. [PMID: 30279682 PMCID: PMC6153309 DOI: 10.3389/fmicb.2018.02197] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 08/28/2018] [Indexed: 12/14/2022] Open
Abstract
Escherichia coli swarm on semi-solid surfaces with the aid of flagella. It has been hypothesized that swarmer cells overcome the increased viscous drag near surfaces by developing higher flagellar thrust and by promoting surface wetness with the aid of a flagellar switch. The switch enables reversals between clockwise (CW) and counterclockwise (CCW) directions of rotation of the flagellar motor. Here, we measured the behavior of flagellar motors in swarmer cells. Results indicated that although the torque was similar to that in planktonic cells, the tendency to rotate CCW was higher in swarmer cells. This suggested that swarmers likely have a smaller pool of phosphorylated CheY. Results further indicated that the upregulation of the flagellin gene was not critical for flagellar thrust or swarming. Consistent with earlier reports, moisture added to the swarm surface restored swarming in a CCW-only mutant, but not in a FliG mutant that rotated motors CW-only (FliGCW). Fluorescence assays revealed that FliGCW cells grown on agar surfaces carried fewer flagella than planktonic FliGCW cells. The surface-dependent reduction in flagella correlated with a reduction in the number of putative flagellar preassemblies. These results hint toward a possibility that the conformational dynamics of switch proteins play a role in the proper assembly of flagellar complexes and flagellar export, thereby aiding bacterial swarming.
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Affiliation(s)
- Katie M Ford
- Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, TX, United States
| | - Jyot D Antani
- Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, TX, United States
| | - Aravindh Nagarajan
- Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, TX, United States
| | - Madeline M Johnson
- Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, TX, United States
| | - Pushkar P Lele
- Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, TX, United States
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Wytock TP, Fiebig A, Willett JW, Herrou J, Fergin A, Motter AE, Crosson S. Experimental evolution of diverse Escherichia coli metabolic mutants identifies genetic loci for convergent adaptation of growth rate. PLoS Genet 2018; 14:e1007284. [PMID: 29584733 PMCID: PMC5892946 DOI: 10.1371/journal.pgen.1007284] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Revised: 04/10/2018] [Accepted: 03/02/2018] [Indexed: 01/08/2023] Open
Abstract
Cell growth is determined by substrate availability and the cell’s metabolic capacity to assimilate substrates into building blocks. Metabolic genes that determine growth rate may interact synergistically or antagonistically, and can accelerate or slow growth, depending on genetic background and environmental conditions. We evolved a diverse set of Escherichia coli single-gene deletion mutants with a spectrum of growth rates and identified mutations that generally increase growth rate. Despite the metabolic differences between parent strains, mutations that enhanced growth largely mapped to core transcription machinery, including the β and β’ subunits of RNA polymerase (RNAP) and the transcription elongation factor, NusA. The structural segments of RNAP that determine enhanced growth have been previously implicated in antibiotic resistance and in the control of transcription elongation and pausing. We further developed a computational framework to characterize how the transcriptional changes that occur upon acquisition of these mutations affect growth rate across strains. Our experimental and computational results provide evidence for cases in which RNAP mutations shift the competitive balance between active transcription and gene silencing. This study demonstrates that mutations in specific regions of RNAP are a convergent adaptive solution that can enhance the growth rate of cells from distinct metabolic states. The loss of a metabolic function caused by gene deletion can be compensated, in certain cases, by the concurrent mutation of a second gene. Whether such gene pairs share a local chemical or regulatory relationship or interact via a non-local mechanism has implications for the co-evolution of genetic changes, development of alternatives to gene therapy, and the design of combination antimicrobial therapies that select against resistance. Yet, we lack a comprehensive knowledge of adaptive responses to metabolic mutations, and our understanding of the mechanisms underlying genetic rescue remains limited. We present results of a laboratory evolution approach that has the potential to address both challenges, showing that mutations in specific regions of RNA polymerase enhance growth rates of distinct mutant strains of Escherichia coli with a spectrum of growth defects. Several of these adaptive mutations are deleterious when engineered directly into the original wild-type strain under alternative cultivation conditions, and thus have epistatic rescue properties when paired with the corresponding primary metabolic gene deletions. Our combination of adaptive evolution, directed genetic engineering, and mathematical analysis of transcription and growth rate distinguishes between rescue interactions that are specific or non-specific to a particular deletion. Our study further supports a model for RNA polymerase as a locus of convergent adaptive evolution from different sub-optimal metabolic starting points.
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Affiliation(s)
- Thomas P. Wytock
- Department of Physics and Astronomy, Northwestern University, Evanston, Illinois, United States of America
| | - Aretha Fiebig
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois, United States of America
| | - Jonathan W. Willett
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois, United States of America
| | - Julien Herrou
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois, United States of America
| | - Aleksandra Fergin
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois, United States of America
| | - Adilson E. Motter
- Department of Physics and Astronomy, Northwestern University, Evanston, Illinois, United States of America
- Northwestern Institute on Complex Systems, Northwestern University, Evanston, Illinois, United States of America
- * E-mail: (AEM); (SC)
| | - Sean Crosson
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois, United States of America
- Department of Microbiology, University of Chicago, Chicago, Illinois, United States of America
- * E-mail: (AEM); (SC)
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Liew CW, Hynson RM, Ganuelas LA, Shah-Mohammadi N, Duff AP, Kojima S, Homma M, Lee LK. Solution structure analysis of the periplasmic region of bacterial flagellar motor stators by small angle X-ray scattering. Biochem Biophys Res Commun 2017; 495:1614-1619. [PMID: 29197577 DOI: 10.1016/j.bbrc.2017.11.194] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Accepted: 11/28/2017] [Indexed: 01/18/2023]
Abstract
The bacterial flagellar motor drives the rotation of helical flagellar filaments to propel bacteria through viscous media. It consists of a dynamic population of mechanosensitive stators that are embedded in the inner membrane and activate in response to external load. This entails assembly around the rotor, anchoring to the peptidoglycan layer to counteract torque from the rotor and opening of a cation channel to facilitate an influx of cations, which is converted into mechanical rotation. Stator complexes are comprised of four copies of an integral membrane A subunit and two copies of a B subunit. Each B subunit includes a C-terminal OmpA-like peptidoglycan-binding (PGB) domain. This is thought to be linked to a single N-terminal transmembrane helix by a long unstructured peptide, which allows the PGB domain to bind to the peptidoglycan layer during stator anchoring. The high-resolution crystal structures of flagellar motor PGB domains from Salmonella enterica (MotBC2) and Vibrio alginolyticus (PomBC5) have previously been elucidated. Here, we use small-angle X-ray scattering (SAXS). We show that unlike MotBC2, the dimeric conformation of the PomBC5 in solution differs to its crystal structure, and explore the functional relevance by characterising gain-of-function mutants as well as wild-type constructs of various lengths. These provide new insight into the conformational diversity of flagellar motor PGB domains and experimental verification of their overall topology.
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Affiliation(s)
- C W Liew
- School of Medical Sciences, The University of New South Wales, Australia
| | - R M Hynson
- Structural and Computational Biology Division, The Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales, Australia
| | - L A Ganuelas
- School of Medical Sciences, The University of New South Wales, Australia
| | - N Shah-Mohammadi
- Structural and Computational Biology Division, The Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales, Australia; Climate Change Cluster, University of Technology Sydney, Ultimo, New South Wales, Australia
| | - A P Duff
- Australian Nuclear and Science Technology Organisation, Lucas Heights, New South Wales, Australia
| | - S Kojima
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-Ku, Nagoya 464-8602, Japan
| | - M Homma
- Division of Biological Science, Graduate School of Science, Nagoya University, Chikusa-Ku, Nagoya 464-8602, Japan
| | - L K Lee
- School of Medical Sciences, The University of New South Wales, Australia; Structural and Computational Biology Division, The Victor Chang Cardiac Research Institute, Darlinghurst, New South Wales, Australia.
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44
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Schneider JP, Basler M. Shedding light on biology of bacterial cells. Philos Trans R Soc Lond B Biol Sci 2017; 371:rstb.2015.0499. [PMID: 27672150 PMCID: PMC5052743 DOI: 10.1098/rstb.2015.0499] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/06/2016] [Indexed: 12/11/2022] Open
Abstract
To understand basic principles of living organisms one has to know many different properties of all cellular components, their mutual interactions but also their amounts and spatial organization. Live-cell imaging is one possible approach to obtain such data. To get multiple snapshots of a cellular process, the imaging approach has to be gentle enough to not disrupt basic functions of the cell but also have high temporal and spatial resolution to detect and describe the changes. Light microscopy has become a method of choice and since its early development over 300 years ago revolutionized our understanding of living organisms. As most cellular components are indistinguishable from the rest of the cellular contents, the second revolution came from a discovery of specific labelling techniques, such as fusions to fluorescent proteins that allowed specific tracking of a component of interest. Currently, several different tags can be tracked independently and this allows us to simultaneously monitor the dynamics of several cellular components and from the correlation of their dynamics to infer their respective functions. It is, therefore, not surprising that live-cell fluorescence microscopy significantly advanced our understanding of basic cellular processes. Current cameras are fast enough to detect changes with millisecond time resolution and are sensitive enough to detect even a few photons per pixel. Together with constant improvement of properties of fluorescent tags, it is now possible to track single molecules in living cells over an extended period of time with a great temporal resolution. The parallel development of new illumination and detection techniques allowed breaking the diffraction barrier and thus further pushed the resolution limit of light microscopy. In this review, we would like to cover recent advances in live-cell imaging technology relevant to bacterial cells and provide a few examples of research that has been possible due to imaging. This article is part of the themed issue ‘The new bacteriology’.
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Affiliation(s)
- Johannes P Schneider
- Focal Area Infection Biology, Biozentrum, University of Basel, 4056 Basel, Switzerland
| | - Marek Basler
- Focal Area Infection Biology, Biozentrum, University of Basel, 4056 Basel, Switzerland
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45
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Transcriptional control of motility enables directional movement of Escherichia coli in a signal gradient. Sci Rep 2017; 7:8959. [PMID: 28827562 PMCID: PMC5566481 DOI: 10.1038/s41598-017-08870-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Accepted: 07/18/2017] [Indexed: 11/08/2022] Open
Abstract
Manipulation of cellular motility using a target signal can facilitate the development of biosensors or microbe-powered biorobots. Here, we engineered signal-dependent motility in Escherichia coli via the transcriptional control of a key motility gene. Without manipulating chemotaxis, signal-dependent switching of motility, either on or off, led to population-level directional movement of cells up or down a signal gradient. We developed a mathematical model that captures the behaviour of the cells, enables identification of key parameters controlling system behaviour, and facilitates predictive-design of motility-based pattern formation. We demonstrated that motility of the receiver strains could be controlled by a sender strain generating a signal gradient. The modular quorum sensing-dependent architecture for interfacing different senders with receivers enabled a broad range of systems-level behaviours. The directional control of motility, especially combined with the potential to incorporate tuneable sensors and more complex sensing-logic, may lead to tools for novel biosensing and targeted-delivery applications.
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46
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Fabiani FD, Renault TT, Peters B, Dietsche T, Gálvez EJC, Guse A, Freier K, Charpentier E, Strowig T, Franz-Wachtel M, Macek B, Wagner S, Hensel M, Erhardt M. A flagellum-specific chaperone facilitates assembly of the core type III export apparatus of the bacterial flagellum. PLoS Biol 2017; 15:e2002267. [PMID: 28771474 PMCID: PMC5542435 DOI: 10.1371/journal.pbio.2002267] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Accepted: 06/30/2017] [Indexed: 11/21/2022] Open
Abstract
Many bacteria move using a complex, self-assembling nanomachine, the bacterial flagellum. Biosynthesis of the flagellum depends on a flagellar-specific type III secretion system (T3SS), a protein export machine homologous to the export machinery of the virulence-associated injectisome. Six cytoplasmic (FliH/I/J/G/M/N) and seven integral-membrane proteins (FlhA/B FliF/O/P/Q/R) form the flagellar basal body and are involved in the transport of flagellar building blocks across the inner membrane in a proton motive force-dependent manner. However, how the large, multi-component transmembrane export gate complex assembles in a coordinated manner remains enigmatic. Specific for most flagellar T3SSs is the presence of FliO, a small bitopic membrane protein with a large cytoplasmic domain. The function of FliO is unknown, but homologs of FliO are found in >80% of all flagellated bacteria. Here, we demonstrate that FliO protects FliP from proteolytic degradation and promotes the formation of a stable FliP–FliR complex required for the assembly of a functional core export apparatus. We further reveal the subcellular localization of FliO by super-resolution microscopy and show that FliO is not part of the assembled flagellar basal body. In summary, our results suggest that FliO functions as a novel, flagellar T3SS-specific chaperone, which facilitates quality control and productive assembly of the core T3SS export machinery. Many bacteria use the bacterial flagellum for directed movement in various environments. The assembly and function of the bacterial flagellum and the related virulence-associated injectisome relies on protein export via a conserved type III secretion system (T3SS). The multicomponent transmembrane core export apparatus of the flagellar T3SS consists of FlhA/B and FliP/Q/R and must assemble in a highly coordinated manner. In the present study, we determined the role of the transmembrane protein FliO in the maturation of the flagellar core protein export apparatus. We show that FliO functions as a flagellum-specific chaperone during the initial step of export apparatus assembly. FliO facilitates the efficient formation of a stable FliP–FliR core complex and is thus required for quality management and productive assembly of the flagellar export apparatus. Our results suggest a coordinated assembly process of the flagellar core export apparatus that nucleates with the FliO-dependent formation of a FliP–FliR complex. Subsequent incorporation of FliQ, FlhB, and FlhA leads to the assembly of a secretion-competent flagellar T3SS.
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Affiliation(s)
- Florian D. Fabiani
- Junior Research Group Infection Biology of Salmonella, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Thibaud T. Renault
- Junior Research Group Infection Biology of Salmonella, Helmholtz Centre for Infection Research, Braunschweig, Germany
- Max Planck Institute for Infection Biology, Berlin, Germany
| | - Britta Peters
- Abteilung Mikrobiologie, Fachbereich Biologie/Chemie, University of Osnabrück, Osnabrück, Germany
| | - Tobias Dietsche
- Interfaculty Institute of Microbiology and Infection Medicine (IMIT), Section of Cellular and Molecular Microbiology, University of Tübingen, Tübingen, Germany
| | - Eric J. C. Gálvez
- Junior Research Group Microbial Immune Regulation, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Alina Guse
- Junior Research Group Infection Biology of Salmonella, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | - Karen Freier
- Junior Research Group Infection Biology of Salmonella, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | | | - Till Strowig
- Junior Research Group Microbial Immune Regulation, Helmholtz Centre for Infection Research, Braunschweig, Germany
| | | | - Boris Macek
- Proteome Center Tübingen, University of Tübingen, Tübingen, Germany
| | - Samuel Wagner
- Interfaculty Institute of Microbiology and Infection Medicine (IMIT), Section of Cellular and Molecular Microbiology, University of Tübingen, Tübingen, Germany
- German Center for Infection Research (DZIF), Partner-site Tübingen, Tübingen, Germany
| | - Michael Hensel
- Abteilung Mikrobiologie, Fachbereich Biologie/Chemie, University of Osnabrück, Osnabrück, Germany
| | - Marc Erhardt
- Junior Research Group Infection Biology of Salmonella, Helmholtz Centre for Infection Research, Braunschweig, Germany
- * E-mail:
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Kim EA, Panushka J, Meyer T, Ide N, Carlisle R, Baker S, Blair DF. Biogenesis of the Flagellar Switch Complex in Escherichia coli: Formation of Sub-Complexes Independently of the Basal-Body MS-Ring. J Mol Biol 2017. [PMID: 28625846 DOI: 10.1016/j.jmb.2017.06.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Direction switching in the flagellar motor of Escherichia coli is under the control of a complex on the rotor formed from the proteins FliG, FliM, and FliN. FliG lies at the top of the switch complex (i.e., nearest the membrane) and is arranged with its C-terminal domain (FliGC) resting on the middle domain (FliGM) of the neighboring subunit. This organization requires the protein to adopt an open conformation that exposes the surfaces engaging in intersubunit FliGC/FliGM contacts. In a recent study, Baker and coworkers [13] obtained evidence that FliG in the cytosol is monomeric and takes on a more compact conformation, with FliGC making intramolecular contact with FliGM of the same subunit. In the present work, we examine the conformational preferences and interactions of FliG through in vivo crosslinking experiments in cells that lack either all other flagellar proteins or just the MS-ring protein FliF. The results indicate that FliG has a significant tendency to form multimers independently of other flagellar components. The multimerization of FliG is promoted by FliF and also by FliM. FliM does not multimerize efficiently by itself but does so in the presence of FliG. Thus, pre-assemblies of the switch-complex proteins can form in the cytosol and might function as intermediates in assembly.
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Affiliation(s)
- Eun A Kim
- Department of Biology, University of Utah, Salt Lake City, UT 84112, USA
| | - Joseph Panushka
- Department of Biology, University of Utah, Salt Lake City, UT 84112, USA
| | - Trevor Meyer
- Department of Biology, University of Utah, Salt Lake City, UT 84112, USA
| | - Nicholas Ide
- Department of Biology, University of Utah, Salt Lake City, UT 84112, USA
| | - Ryan Carlisle
- Department of Biology, University of Utah, Salt Lake City, UT 84112, USA
| | - Samantha Baker
- Department of Biology, University of Utah, Salt Lake City, UT 84112, USA
| | - David F Blair
- Department of Biology, University of Utah, Salt Lake City, UT 84112, USA.
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48
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Wang S, Liu X, Xu X, Yang D, Wang D, Han X, Shi Y, Tian M, Ding C, Peng D, Yu S. Escherichia coli Type III Secretion System 2 ATPase EivC Is Involved in the Motility and Virulence of Avian Pathogenic Escherichia coli. Front Microbiol 2016; 7:1387. [PMID: 27630634 PMCID: PMC5005338 DOI: 10.3389/fmicb.2016.01387] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2016] [Accepted: 08/22/2016] [Indexed: 01/13/2023] Open
Abstract
Type III secretion systems (T3SSs) are crucial for bacterial infections because they deliver effector proteins into host cells. The Escherichia coli type III secretion system 2 (ETT2) is present in the majority of E. coli strains, and although it is degenerate, ETT2 regulates bacterial virulence. An ATPase is essential for T3SS secretion, but the function of the ETT2 ATPase has not been demonstrated. Here, we show that EivC is homologous to the β subunit of F0F1 ATPases and it possesses ATPase activity. To investigate the effects of ETT2 ATPase EivC on the phenotype and virulence of avian pathogenic Escherichia coli (APEC), eivC mutant and complemented strains were constructed and characterized. Inactivation of eivC led to impaired flagella production and augmented fimbriae on the bacterial surface, and, consequently, reduced bacterial motility. In addition, the eivC mutant strain exhibited attenuated virulence in ducks, diminished serum resistance, reduced survival in macrophage cells and in ducks, upregulated fimbrial gene expression, and downregulated flagellar and virulence gene expression. The expression of the inflammatory cytokines interleukin (IL)-1β and IL-8 were increased in HD-11 macrophages infected with the eivC mutant strain, compared with the wild-type strain. These virulence-related phenotypes were restored by genetic complementation. These findings demonstrate that ETT2 ATPase EivC is involved in the motility and pathogenicity of APEC.
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Affiliation(s)
- Shaohui Wang
- Shanghai Veterinary Research Institute - Chinese Academy of Agricultural Sciences Shanghai, China
| | - Xin Liu
- Shanghai Veterinary Research Institute - Chinese Academy of Agricultural SciencesShanghai, China; College of Veterinary Medicine, Yangzhou UniversityYangzhou, China
| | - Xuan Xu
- Shanghai Veterinary Research Institute - Chinese Academy of Agricultural Sciences Shanghai, China
| | - Denghui Yang
- Shanghai Veterinary Research Institute - Chinese Academy of Agricultural Sciences Shanghai, China
| | - Dong Wang
- Shanghai Veterinary Research Institute - Chinese Academy of Agricultural Sciences Shanghai, China
| | - Xiangan Han
- Shanghai Veterinary Research Institute - Chinese Academy of Agricultural Sciences Shanghai, China
| | - Yonghong Shi
- Shanghai Veterinary Research Institute - Chinese Academy of Agricultural Sciences Shanghai, China
| | - Mingxing Tian
- Shanghai Veterinary Research Institute - Chinese Academy of Agricultural Sciences Shanghai, China
| | - Chan Ding
- Shanghai Veterinary Research Institute - Chinese Academy of Agricultural Sciences Shanghai, China
| | - Daxin Peng
- College of Veterinary Medicine, Yangzhou University Yangzhou, China
| | - Shengqing Yu
- Shanghai Veterinary Research Institute - Chinese Academy of Agricultural Sciences Shanghai, China
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Rodrigues CDA, Ramírez-Guadiana FH, Meeske AJ, Wang X, Rudner DZ. GerM is required to assemble the basal platform of the SpoIIIA-SpoIIQ transenvelope complex during sporulation in Bacillus subtilis. Mol Microbiol 2016; 102:260-273. [PMID: 27381174 DOI: 10.1111/mmi.13457] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/02/2016] [Indexed: 11/29/2022]
Abstract
Sporulating Bacillus subtilis cells assemble a multimeric membrane complex connecting the mother cell and developing spore that is required to maintain forespore differentiation. An early step in the assembly of this transenvelope complex (called the A-Q complex) is an interaction between the extracellular domains of the forespore membrane protein SpoIIQ and the mother cell membrane protein SpoIIIAH. This interaction provides a platform onto which the remaining components of the complex assemble and also functions as an anchor for cell-cell signalling and morphogenetic proteins involved in spore development. SpoIIQ is required to recruit SpoIIIAH to the sporulation septum on the mother cell side; however, the mechanism by which SpoIIQ specifically localizes to the septal membranes on the forespore side has remained enigmatic. Here, we identify GerM, a lipoprotein previously implicated in spore germination, as the missing factor required for SpoIIQ localization. Our data indicate that GerM and SpoIIIAH, derived from the mother cell, and SpoIIQ, from the forespore, have reciprocal localization dependencies suggesting they constitute a tripartite platform for the assembly of the A-Q complex and a hub for the localization of mother cell and forespore proteins.
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Affiliation(s)
- Christopher D A Rodrigues
- Department of Microbiology and Immunobiology, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA, 02115, USA
| | - Fernando H Ramírez-Guadiana
- Department of Microbiology and Immunobiology, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA, 02115, USA
| | - Alexander J Meeske
- Department of Microbiology and Immunobiology, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA, 02115, USA
| | - Xindan Wang
- Department of Microbiology and Immunobiology, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA, 02115, USA
| | - David Z Rudner
- Department of Microbiology and Immunobiology, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA, 02115, USA.
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50
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Garcie C, Tronnet S, Garénaux A, McCarthy AJ, Brachmann AO, Pénary M, Houle S, Nougayrède JP, Piel J, Taylor PW, Dozois CM, Genevaux P, Oswald E, Martin P. The Bacterial Stress-Responsive Hsp90 Chaperone (HtpG) Is Required for the Production of the Genotoxin Colibactin and the Siderophore Yersiniabactin inEscherichia coli. J Infect Dis 2016; 214:916-24. [DOI: 10.1093/infdis/jiw294] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Accepted: 07/06/2016] [Indexed: 01/04/2023] Open
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