1
|
Minamino T, Kinoshita M. Structure, Assembly, and Function of Flagella Responsible for Bacterial Locomotion. EcoSal Plus 2023; 11:eesp00112023. [PMID: 37260402 PMCID: PMC10729930 DOI: 10.1128/ecosalplus.esp-0011-2023] [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: 01/18/2023] [Accepted: 04/14/2023] [Indexed: 01/28/2024]
Abstract
Many motile bacteria use flagella for locomotion under a variety of environmental conditions. Because bacterial flagella are under the control of sensory signal transduction pathways, each cell is able to autonomously control its flagellum-driven locomotion and move to an environment favorable for survival. The flagellum of Salmonella enterica serovar Typhimurium is a supramolecular assembly consisting of at least three distinct functional parts: a basal body that acts as a bidirectional rotary motor together with multiple force generators, each of which serves as a transmembrane proton channel to couple the proton flow through the channel with torque generation; a filament that functions as a helical propeller that produces propulsion; and a hook that works as a universal joint that transmits the torque produced by the rotary motor to the helical propeller. At the base of the flagellum is a type III secretion system that transports flagellar structural subunits from the cytoplasm to the distal end of the growing flagellar structure, where assembly takes place. In recent years, high-resolution cryo-electron microscopy (cryoEM) image analysis has revealed the overall structure of the flagellum, and this structural information has made it possible to discuss flagellar assembly and function at the atomic level. In this article, we describe what is known about the structure, assembly, and function of Salmonella flagella.
Collapse
Affiliation(s)
- Tohru Minamino
- Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, Japan
| | - Miki Kinoshita
- Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, Japan
| |
Collapse
|
2
|
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.
Collapse
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
| |
Collapse
|
3
|
Minamino T, Morimoto YV, Kinoshita M, Namba K. Multiple Roles of Flagellar Export Chaperones for Efficient and Robust Flagellar Filament Formation in Salmonella. Front Microbiol 2021; 12:756044. [PMID: 34691007 PMCID: PMC8527033 DOI: 10.3389/fmicb.2021.756044] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Accepted: 09/08/2021] [Indexed: 11/30/2022] Open
Abstract
FlgN, FliS, and FliT are flagellar export chaperones specific for FlgK/FlgL, FliC, and FliD, respectively, which are essential component proteins for filament formation. These chaperones facilitate the docking of their cognate substrates to a transmembrane export gate protein, FlhA, to facilitate their subsequent unfolding and export by the flagellar type III secretion system (fT3SS). Dynamic interactions of the chaperones with FlhA are thought to determine the substrate export order. To clarify the role of flagellar chaperones in filament assembly, we constructed cells lacking FlgN, FliS, and/or FliT. Removal of either FlgN, FliS, or FliT resulted in leakage of a large amount of unassembled FliC monomers into the culture media, indicating that these chaperones contribute to robust and efficient filament formation. The ∆flgN ∆fliS ∆fliT (∆NST) cells produced short filaments similarly to the ∆fliS mutant. Suppressor mutations of the ∆NST cells, which lengthened the filament, were all found in FliC and destabilized the folded structure of FliC monomer. Deletion of FliS inhibited FliC export and filament elongation only after FliC synthesis was complete. We propose that FliS is not involved in the transport of FliC upon onset of filament formation, but FliS-assisted unfolding of FliC by the fT3SS becomes essential for its rapid and efficient export to form a long filament when FliC becomes fully expressed in the cytoplasm.
Collapse
Affiliation(s)
- Tohru Minamino
- Graduate School of Frontier Biosciences, Osaka University, Suita, Japan
| | - Yusuke V Morimoto
- Department of Physics and Information Technology, Faculty of Computer Science and Systems Engineering, Kyushu Institute of Technology, Iizuka, Japan.,Japan Science and Technology Agency, PRESTO, Kawaguchi, Japan
| | - Miki Kinoshita
- Graduate School of Frontier Biosciences, Osaka University, Suita, Japan
| | - Keiichi Namba
- Graduate School of Frontier Biosciences, Osaka University, Suita, Japan.,RIKEN SPring-8 Center and Center for Biosystems Dynamics Research, Suita, Japan.,JEOL YOKOGUSHI Research Alliance Laboratories, Osaka University, Suita, Japan
| |
Collapse
|
4
|
Bouteiller M, Dupont C, Bourigault Y, Latour X, Barbey C, Konto-Ghiorghi Y, Merieau A. Pseudomonas Flagella: Generalities and Specificities. Int J Mol Sci 2021; 22:ijms22073337. [PMID: 33805191 PMCID: PMC8036289 DOI: 10.3390/ijms22073337] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Revised: 03/22/2021] [Accepted: 03/22/2021] [Indexed: 12/21/2022] Open
Abstract
Flagella-driven motility is an important trait for bacterial colonization and virulence. Flagella rotate and propel bacteria in liquid or semi-liquid media to ensure such bacterial fitness. Bacterial flagella are composed of three parts: a membrane complex, a flexible-hook, and a flagellin filament. The most widely studied models in terms of the flagellar apparatus are E. coli and Salmonella. However, there are many differences between these enteric bacteria and the bacteria of the Pseudomonas genus. Enteric bacteria possess peritrichous flagella, in contrast to Pseudomonads, which possess polar flagella. In addition, flagellar gene expression in Pseudomonas is under a four-tiered regulatory circuit, whereas enteric bacteria express flagellar genes in a three-step manner. Here, we use knowledge of E. coli and Salmonella flagella to describe the general properties of flagella and then focus on the specificities of Pseudomonas flagella. After a description of flagellar structure, which is highly conserved among Gram-negative bacteria, we focus on the steps of flagellar assembly that differ between enteric and polar-flagellated bacteria. In addition, we summarize generalities concerning the fuel used for the production and rotation of the flagellar macromolecular complex. The last part summarizes known regulatory pathways and potential links with the type-six secretion system (T6SS).
Collapse
Affiliation(s)
- Mathilde Bouteiller
- LMSM, Laboratoire de Microbiologie Signaux et Microenvironnement, EA 4312, Normandy University, Université de Rouen, 27000 Evreux, France; (M.B.); (C.D.); (Y.B.); (X.L.); (C.B.); (Y.K.-G.)
- SFR NORVEGE, Structure Fédérative de Recherche Normandie Végétale, FED 4277, 76821 Mont-Saint-Aignan, France
| | - Charly Dupont
- LMSM, Laboratoire de Microbiologie Signaux et Microenvironnement, EA 4312, Normandy University, Université de Rouen, 27000 Evreux, France; (M.B.); (C.D.); (Y.B.); (X.L.); (C.B.); (Y.K.-G.)
- SFR NORVEGE, Structure Fédérative de Recherche Normandie Végétale, FED 4277, 76821 Mont-Saint-Aignan, France
| | - Yvann Bourigault
- LMSM, Laboratoire de Microbiologie Signaux et Microenvironnement, EA 4312, Normandy University, Université de Rouen, 27000 Evreux, France; (M.B.); (C.D.); (Y.B.); (X.L.); (C.B.); (Y.K.-G.)
- SFR NORVEGE, Structure Fédérative de Recherche Normandie Végétale, FED 4277, 76821 Mont-Saint-Aignan, France
| | - Xavier Latour
- LMSM, Laboratoire de Microbiologie Signaux et Microenvironnement, EA 4312, Normandy University, Université de Rouen, 27000 Evreux, France; (M.B.); (C.D.); (Y.B.); (X.L.); (C.B.); (Y.K.-G.)
- SFR NORVEGE, Structure Fédérative de Recherche Normandie Végétale, FED 4277, 76821 Mont-Saint-Aignan, France
| | - Corinne Barbey
- LMSM, Laboratoire de Microbiologie Signaux et Microenvironnement, EA 4312, Normandy University, Université de Rouen, 27000 Evreux, France; (M.B.); (C.D.); (Y.B.); (X.L.); (C.B.); (Y.K.-G.)
- SFR NORVEGE, Structure Fédérative de Recherche Normandie Végétale, FED 4277, 76821 Mont-Saint-Aignan, France
| | - Yoan Konto-Ghiorghi
- LMSM, Laboratoire de Microbiologie Signaux et Microenvironnement, EA 4312, Normandy University, Université de Rouen, 27000 Evreux, France; (M.B.); (C.D.); (Y.B.); (X.L.); (C.B.); (Y.K.-G.)
- SFR NORVEGE, Structure Fédérative de Recherche Normandie Végétale, FED 4277, 76821 Mont-Saint-Aignan, France
| | - Annabelle Merieau
- LMSM, Laboratoire de Microbiologie Signaux et Microenvironnement, EA 4312, Normandy University, Université de Rouen, 27000 Evreux, France; (M.B.); (C.D.); (Y.B.); (X.L.); (C.B.); (Y.K.-G.)
- SFR NORVEGE, Structure Fédérative de Recherche Normandie Végétale, FED 4277, 76821 Mont-Saint-Aignan, France
- Correspondence:
| |
Collapse
|
5
|
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.
Collapse
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
| |
Collapse
|
6
|
Attieh Z, Mouawad C, Rejasse A, Jehanno I, Perchat S, Hegna IK, Økstad OA, Kallassy Awad M, Sanchis-Borja V, El Chamy L. The fliK Gene Is Required for the Resistance of Bacillus thuringiensis to Antimicrobial Peptides and Virulence in Drosophila melanogaster. Front Microbiol 2020; 11:611220. [PMID: 33391240 PMCID: PMC7775485 DOI: 10.3389/fmicb.2020.611220] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Accepted: 11/18/2020] [Indexed: 11/13/2022] Open
Abstract
Antimicrobial peptides (AMPs) are essential effectors of the host innate immune system and they represent promising molecules for the treatment of multidrug resistant microbes. A better understanding of microbial resistance to these defense peptides is thus prerequisite for the control of infectious diseases. Here, using a random mutagenesis approach, we identify the fliK gene, encoding an internal molecular ruler that controls flagella hook length, as an essential element for Bacillus thuringiensis resistance to AMPs in Drosophila. Unlike its parental strain, that is highly virulent to both wild-type and AMPs deficient mutant flies, the fliK deletion mutant is only lethal to the latter's. In agreement with its conserved function, the fliK mutant is non-flagellated and exhibits highly compromised motility. However, comparative analysis of the fliK mutant phenotype to that of a fla mutant, in which the genes encoding flagella proteins are interrupted, indicate that B. thuringiensis FliK-dependent resistance to AMPs is independent of flagella assembly. As a whole, our results identify FliK as an essential determinant for B. thuringiensis virulence in Drosophila and provide new insights on the mechanisms underlying bacteria resistance to AMPs.
Collapse
Affiliation(s)
- Zaynoun Attieh
- UR-EGP, Faculté des Sciences, Université Saint-Joseph de Beyrouth, Beirut, Lebanon
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, Jouy-en-Josas, France
| | - Carine Mouawad
- UR-EGP, Faculté des Sciences, Université Saint-Joseph de Beyrouth, Beirut, Lebanon
| | - Agnès Rejasse
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, Jouy-en-Josas, France
| | - Isabelle Jehanno
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, Jouy-en-Josas, France
| | - Stéphane Perchat
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, Jouy-en-Josas, France
| | - Ida K. Hegna
- Department of Pharmacy, Centre for Integrative Microbial Evolution (CIME), Faculty of Mathematics and Natural Sciences, University of Oslo, Oslo, Norway
| | - Ole A. Økstad
- Department of Pharmacy, Centre for Integrative Microbial Evolution (CIME), Faculty of Mathematics and Natural Sciences, University of Oslo, Oslo, Norway
| | | | - Vincent Sanchis-Borja
- Université Paris-Saclay, INRAE, AgroParisTech, Micalis Institute, Jouy-en-Josas, France
| | - Laure El Chamy
- UR-EGP, Faculté des Sciences, Université Saint-Joseph de Beyrouth, Beirut, Lebanon
| |
Collapse
|
7
|
Type 1 interferon-dependent repression of NLRC4 and iPLA2 licenses down-regulation of Salmonella flagellin inside macrophages. Proc Natl Acad Sci U S A 2020; 117:29811-29822. [PMID: 33177235 DOI: 10.1073/pnas.2002747117] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Inflammasomes have been implicated in the detection and clearance of a variety of bacterial pathogens, but little is known about whether this innate sensing mechanism has any regulatory effect on the expression of stimulatory ligands by the pathogen. During infection with Salmonella and many other pathogens, flagellin is a major activator of NLRC4 inflammasome-mediated macrophage pyroptosis and pathogen eradication. Salmonella switches to a flagellin-low phenotype as infection progresses to avoid this mechanism of clearance by the host. However, the host cues that Salmonella perceives to undergo this switch remain unclear. Here, we report an unexpected role of the NLRC4 inflammasome in promoting expression of its microbial ligand, flagellin, and identify a role for type 1 IFN signaling in switching of Salmonella to a flagellin-low phenotype. Early in infection, activation of NLRC4 by flagellin initiates pyroptosis and concomitant release of lysophospholipids which in turn enhance expression of flagellin by Salmonella thereby amplifying its ability to elicit cell death. TRIF-dependent production of type 1 IFN, however, later represses NLRC4 and the lysophospholipid biosynthetic enzyme iPLA2, causing a decline in intracellular lysophospholipids that results in down-regulation of flagellin expression by Salmonella These findings reveal a previously unrecognized immune-modulating regulatory cross-talk between endosomal TLR signaling and cytosolic NLR activation with significant implications for the establishment of infection with Salmonella.
Collapse
|
8
|
In Vitro Autonomous Construction of the Flagellar Axial Structure in Inverted Membrane Vesicles. Biomolecules 2020; 10:biom10010126. [PMID: 31940802 PMCID: PMC7022808 DOI: 10.3390/biom10010126] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 01/08/2020] [Accepted: 01/09/2020] [Indexed: 02/07/2023] Open
Abstract
The bacterial flagellum is a filamentous organelle extending from the cell surface. The axial structure of the flagellum consists of the rod, hook, junction, filament, and cap. The axial structure is formed by axial component proteins exported via a specific protein export apparatus in a well-regulated manner. Although previous studies have revealed the outline of the flagellar construction process, the mechanism of axial structure formation, including axial protein export, is still obscure due to difficulties in direct observation of protein export and assembly in vivo. We recently developed an in vitro flagellar protein transport assay system using inverted membrane vesicles (IMVs) and succeeded in reproducing the early stage of flagellar assembly. However, the late stage of the flagellar formation process remained to be examined in the IMVs. In this study, we showed that the filament-type proteins are transported into the IMVs to produce the filament on the hook inside the IMVs. Furthermore, we provide direct evidence that coordinated flagellar protein export and assembly can occur at the post-translational level. These results indicate that the ordered construction of the entire flagellar structure can be regulated by only the interactions between the protein export apparatus, the export substrate proteins, and their cognate chaperones.
Collapse
|
9
|
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
Collapse
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.
| |
Collapse
|
10
|
Green CA, Kamble NS, Court EK, Bryant OJ, Hicks MG, Lennon C, Fraser GM, Wright PC, Stafford GP. Engineering the flagellar type III secretion system: improving capacity for secretion of recombinant protein. Microb Cell Fact 2019; 18:10. [PMID: 30657054 PMCID: PMC6337784 DOI: 10.1186/s12934-019-1058-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Accepted: 01/08/2019] [Indexed: 08/26/2023] Open
Abstract
BACKGROUND Many valuable biopharmaceutical and biotechnological proteins have been produced in Escherichia coli, however these proteins are almost exclusively localised in the cytoplasm or periplasm. This presents challenges for purification, i.e. the removal of contaminating cellular constituents. One solution is secretion directly into the surrounding media, which we achieved via the 'hijack' of the flagellar type III secretion system (FT3SS). Ordinarily flagellar subunits are exported through the centre of the growing flagellum, before assembly at the tip. However, we exploit the fact that in the absence of certain flagellar components (e.g. cap proteins), monomeric flagellar proteins are secreted into the supernatant. RESULTS We report the creation and iterative improvement of an E. coli strain, by means of a modified FT3SS and a modular plasmid system, for secretion of exemplar proteins. We show that removal of the flagellin and HAP proteins (FliC and FlgKL) resulted in an optimal prototype. We next developed a high-throughput enzymatic secretion assay based on cutinase. This indicated that removal of the flagellar motor proteins, motAB (to reduce metabolic burden) and protein degradation machinery, clpX (to boost FT3SS levels intracellularly), result in high capacity secretion. We also show that a secretion construct comprising the 5'UTR and first 47 amino acidsof FliC from E. coli (but no 3'UTR) achieved the highest levels of secretion. Upon combination, we show a 24-fold improvement in secretion of a heterologous (cutinase) enzyme over the original strain. This improved strain could export a range of pharmaceutically relevant heterologous proteins [hGH, TrxA, ScFv (CH2)], achieving secreted yields of up to 0.29 mg L-1, in low cell density culture. CONCLUSIONS We have engineered an E. coli which secretes a range of recombinant proteins, through the FT3SS, to the extracellular media. With further developments, including cell culture process strategies, we envision further improvement to the secreted titre of recombinant protein, with the potential application for protein production for biotechnological purposes.
Collapse
Affiliation(s)
- Charlotte A Green
- Integrated BioSciences, School of Clinical Dentistry, University of Sheffield, Sheffield, S10 2TA, UK.,Sustainable Process Technologies, Chemical and Environmental Engineering, University of Nottingham, Nottingham, NG7 2RD, UK
| | - Nitin S Kamble
- Integrated BioSciences, School of Clinical Dentistry, University of Sheffield, Sheffield, S10 2TA, UK
| | - Elizabeth K Court
- Integrated BioSciences, School of Clinical Dentistry, University of Sheffield, Sheffield, S10 2TA, UK
| | - Owain J Bryant
- Department of Pathology, University of Cambridge, Cambridge, CB2 1QP, UK
| | - Matthew G Hicks
- Integrated BioSciences, School of Clinical Dentistry, University of Sheffield, Sheffield, S10 2TA, UK
| | - Christopher Lennon
- FUJIFILM Diosynth Biotechnologies, Belasis Avenue, Stockton-on-Tees, Billingham, TS23 1LH, UK
| | - Gillian M Fraser
- Department of Pathology, University of Cambridge, Cambridge, CB2 1QP, UK
| | - Phillip C Wright
- School of Engineering, The Faculty of Science, Agriculture and Engineering, Newcastle University, Newcastle, NE1 7RU, UK
| | - Graham P Stafford
- Integrated BioSciences, School of Clinical Dentistry, University of Sheffield, Sheffield, S10 2TA, UK.
| |
Collapse
|
11
|
Altegoer F, Mukherjee S, Steinchen W, Bedrunka P, Linne U, Kearns DB, Bange G. FliS/flagellin/FliW heterotrimer couples type III secretion and flagellin homeostasis. Sci Rep 2018; 8:11552. [PMID: 30068950 PMCID: PMC6070490 DOI: 10.1038/s41598-018-29884-8] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Accepted: 07/20/2018] [Indexed: 01/08/2023] Open
Abstract
Flagellin is amongst the most abundant proteins in flagellated bacterial species and constitutes the major building block of the flagellar filament. The proteins FliW and FliS serve in the post-transcriptional control of flagellin and guide the protein to the flagellar type III secretion system (fT3SS), respectively. Here, we present the high-resolution structure of FliS/flagellin heterodimer and show that FliS and FliW bind to opposing interfaces located at the N- and C-termini of flagellin. The FliS/flagellin/FliW heterotrimer is able to interact with FlhA-C suggesting that FliW and FliS are released during flagellin export. After release, FliW and FliS are recycled to execute a new round of post-transcriptional regulation and targeting. Taken together, our study provides a mechanism explaining how FliW and FliS synchronize the production of flagellin with the capacity of the fT3SS to secrete flagellin.
Collapse
Affiliation(s)
- Florian Altegoer
- LOEWE Center for Synthetic Microbiology & Dep. of Chemistry, Philipps University Marburg, Hans-Meerwein-Strasse 6, 35043, Marburg, Germany
| | - Sampriti Mukherjee
- Department of Biology, Indiana University, 1001 East 3rd Street, Bloomington, IN, 47405, USA
| | - Wieland Steinchen
- LOEWE Center for Synthetic Microbiology & Dep. of Chemistry, Philipps University Marburg, Hans-Meerwein-Strasse 6, 35043, Marburg, Germany
| | - Patricia Bedrunka
- LOEWE Center for Synthetic Microbiology & Dep. of Chemistry, Philipps University Marburg, Hans-Meerwein-Strasse 6, 35043, Marburg, Germany
| | - Uwe Linne
- LOEWE Center for Synthetic Microbiology & Dep. of Chemistry, Philipps University Marburg, Hans-Meerwein-Strasse 6, 35043, Marburg, Germany
| | - Daniel B Kearns
- Department of Biology, Indiana University, 1001 East 3rd Street, Bloomington, IN, 47405, USA
| | - Gert Bange
- LOEWE Center for Synthetic Microbiology & Dep. of Chemistry, Philipps University Marburg, Hans-Meerwein-Strasse 6, 35043, Marburg, Germany.
| |
Collapse
|
12
|
Das C, Mokashi C, Mande SS, Saini S. Dynamics and Control of Flagella Assembly in Salmonella typhimurium. Front Cell Infect Microbiol 2018; 8:36. [PMID: 29473025 PMCID: PMC5809477 DOI: 10.3389/fcimb.2018.00036] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2017] [Accepted: 01/25/2018] [Indexed: 11/13/2022] Open
Abstract
The food-borne pathogen Salmonella typhimurium is a common cause of infections and diseases in a wide range of hosts. One of the major virulence factors associated to the infection process is flagella, which helps the bacterium swim to its preferred site of infection inside the host, the M-cells (Microfold cells) lining the lumen of the small intestine. The expression of flagellar genes is controlled by an intricate regulatory network. In this work, we investigate two aspects of flagella regulation and assembly: (a) distribution of the number of flagella in an isogenic population of bacteria and (b) dynamics of gene expression post cell division. More precisely, in a population of bacteria, we note a normal distribution of number of flagella assembled per cell. How is this distribution controlled, and what are the key regulators in the network which help the cell achieve this? In the second question, we explore the role of protein secretion in dictating gene expression dynamics post cell-division (when the number of hook basal bodies on the cell surface is reduced by a factor of two). We develop a mathematical model and perform stochastic simulations to address these questions. Simulations of the model predict that two accessory regulators of flagella gene expression, FliZ and FliT, have significant roles in maintaining population level distribution of flagella. In addition, FliT and FlgM were predicted to control the level and temporal order of flagellar gene expression when the cell adapts to post cell division consequences. Further, the model predicts that, the FliZ and FliT dependent feedback loops function under certain thresholds, alterations in which can substantially affect kinetics of flagellar genes. Thus, based on our results we propose that, the proteins FlgM, FliZ, and FliT, thought to have accessory roles in regulation of flagella, likely play a critical role controlling gene expression during cell division, and frequency distribution of flagella.
Collapse
Affiliation(s)
- Chandrani Das
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Mumbai, India.,Bio-Sciences R&D Division, TCS Research, Tata Consultancy Services Limited, Pune, India
| | - Chaitanya Mokashi
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Mumbai, India
| | - Sharmila S Mande
- Bio-Sciences R&D Division, TCS Research, Tata Consultancy Services Limited, Pune, India
| | - Supreet Saini
- Department of Chemical Engineering, Indian Institute of Technology Bombay, Mumbai, India
| |
Collapse
|
13
|
Osterman IA, Dikhtyar YY, Bogdanov AA, Dontsova OA, Sergiev PV. Regulation of Flagellar Gene Expression in Bacteria. BIOCHEMISTRY (MOSCOW) 2016; 80:1447-56. [PMID: 26615435 DOI: 10.1134/s000629791511005x] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The flagellum of a bacterium is a supramolecular structure of extreme complexity comprising simultaneously both a unique system of protein transport and a molecular machine that enables the bacterial cell movement. The cascade of expression of genes encoding flagellar components is closely coordinated with the steps of molecular machine assembly, constituting an amazing regulatory system. Data on structure, assembly, and regulation of flagellar gene expression are summarized in this review. The regulatory mechanisms and correlation of the process of regulation of gene expression and flagellum assembly known from the literature are described.
Collapse
Affiliation(s)
- I A Osterman
- Lomonosov Moscow State University, Faculty of Chemistry, Moscow, 119991, Russia.
| | | | | | | | | |
Collapse
|
14
|
Kinoshita M, Nakanishi Y, Furukawa Y, Namba K, Imada K, Minamino T. Rearrangements of α-helical structures of FlgN chaperone control the binding affinity for its cognate substrates during flagellar type III export. Mol Microbiol 2016; 101:656-70. [PMID: 27178222 DOI: 10.1111/mmi.13415] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/05/2016] [Indexed: 11/29/2022]
Abstract
The bacterial flagellar type III export chaperones not only act as bodyguards to protect their cognate substrates from aggregation and proteolysis in the cytoplasm but also ensure the order of export through their interactions with an export gate protein FlhA. FlgN chaperone binds to FlgK and FlgL with nanomolar affinity and transfers them to FlhA for their efficient and rapid transport for the formation of the hook-filament junction zone. However, it remains unknown how FlgN releases FlgK and FlgL at the FlhA export gate platform in a timely manner. Here, we have solved the crystal structure of Salmonella FlgN at 2.3 Å resolution and carried out structure-based functional analyses. FlgN consists of three α helices, α1, α2 and α3. Helix α1 adopts two distinct, extended and bent conformations through the conformational change of N-loop between α1 and α2. The N-loop deletion not only increases the probability of FlgN dimer formation but also abolish the interaction between FlgN and FlgK. Highly conserved Asn-92, Asn-95 and Ile-103 residues in helix α3 are involved in the strong interaction with FlgK. We propose that the N-loop coordinates helical rearrangements of FlgN with the association and dissociation of its cognate substrates during their export.
Collapse
Affiliation(s)
- Miki Kinoshita
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka, 565-0871, Japan.,Department of Macromolecular Science, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka, 560-0043, Japan
| | - Yuki Nakanishi
- Department of Macromolecular Science, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka, 560-0043, Japan
| | - Yukio Furukawa
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Keiichi Namba
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka, 565-0871, Japan.,Quantitative Biology Center, Riken, 1-3 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Katsumi Imada
- Department of Macromolecular Science, Graduate School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka, Osaka, 560-0043, Japan
| | - Tohru Minamino
- Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita, Osaka, 565-0871, Japan
| |
Collapse
|
15
|
Scheibner F, Schulz S, Hausner J, Marillonnet S, Büttner D. Type III-Dependent Translocation of HrpB2 by a Nonpathogenic hpaABC Mutant of the Plant-Pathogenic Bacterium Xanthomonas campestris pv. vesicatoria. Appl Environ Microbiol 2016; 82:3331-3347. [PMID: 27016569 PMCID: PMC4959247 DOI: 10.1128/aem.00537-16] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Accepted: 03/21/2016] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED The plant-pathogenic bacterium Xanthomonas campestris pv. vesicatoria employs a type III secretion (T3S) system to translocate effector proteins into plant cells. The T3S apparatus spans both bacterial membranes and is associated with an extracellular pilus and a channel-like translocon in the host plasma membrane. T3S is controlled by the switch protein HpaC, which suppresses secretion and translocation of the predicted inner rod protein HrpB2 and promotes secretion of translocon and effector proteins. We previously reported that HrpB2 interacts with HpaC and the cytoplasmic domain of the inner membrane protein HrcU (C. Lorenz, S. Schulz, T. Wolsch, O. Rossier, U. Bonas, and D. Büttner, PLoS Pathog 4:e1000094, 2008, http://dx.doi.org/10.1371/journal.ppat.1000094). However, the molecular mechanisms underlying the control of HrpB2 secretion are not yet understood. Here, we located a T3S and translocation signal in the N-terminal 40 amino acids of HrpB2. The results of complementation experiments with HrpB2 deletion derivatives revealed that the T3S signal of HrpB2 is essential for protein function. Furthermore, interaction studies showed that the N-terminal region of HrpB2 interacts with the cytoplasmic domain of HrcU, suggesting that the T3S signal of HrpB2 contributes to substrate docking. Translocation of HrpB2 is suppressed not only by HpaC but also by the T3S chaperone HpaB and its secreted regulator, HpaA. Deletion of hpaA, hpaB, and hpaC leads to a loss of pathogenicity but allows the translocation of fusion proteins between the HrpB2 T3S signal and effector proteins into leaves of host and non-host plants. IMPORTANCE The T3S system of the plant-pathogenic bacterium Xanthomonas campestris pv. vesicatoria is essential for pathogenicity and delivers effector proteins into plant cells. T3S depends on HrpB2, which is a component of the predicted periplasmic inner rod structure of the secretion apparatus. HrpB2 is secreted during the early stages of the secretion process and interacts with the cytoplasmic domain of the inner membrane protein HrcU. Here, we localized the secretion and translocation signal of HrpB2 in the N-terminal 40 amino acids and show that this region is sufficient for the interaction with the cytoplasmic domain of HrcU. Our results suggest that the T3S signal of HrpB2 is required for the docking of HrpB2 to the secretion apparatus. Furthermore, we provide experimental evidence that the N-terminal region of HrpB2 is sufficient to target effector proteins for translocation in a nonpathogenic X. campestris pv. vesicatoria strain.
Collapse
Affiliation(s)
- Felix Scheibner
- Institute of Biology, Department of Genetics, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
| | - Steve Schulz
- Institute of Biology, Department of Genetics, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
| | - Jens Hausner
- Institute of Biology, Department of Genetics, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
| | | | - Daniela Büttner
- Institute of Biology, Department of Genetics, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
| |
Collapse
|
16
|
The CsrA-FliW network controls polar localization of the dual-function flagellin mRNA in Campylobacter jejuni. Nat Commun 2016; 7:11667. [PMID: 27229370 PMCID: PMC4894983 DOI: 10.1038/ncomms11667] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2015] [Accepted: 04/18/2016] [Indexed: 12/12/2022] Open
Abstract
The widespread CsrA/RsmA protein regulators repress translation by binding GGA motifs in bacterial mRNAs. CsrA activity is primarily controlled through sequestration by multiple small regulatory RNAs. Here we investigate CsrA activity control in the absence of antagonizing small RNAs by examining the CsrA regulon in the human pathogen Campylobacter jejuni. We use genome-wide co-immunoprecipitation combined with RNA sequencing to show that CsrA primarily binds flagellar mRNAs and identify the major flagellin mRNA (flaA) as the main CsrA target. The flaA mRNA is translationally repressed by CsrA, but it can also titrate CsrA activity. Together with the main C. jejuni CsrA antagonist, the FliW protein, flaA mRNA controls CsrA-mediated post-transcriptional regulation of other flagellar genes. RNA-FISH reveals that flaA mRNA is expressed and localized at the poles of elongating cells. Polar flaA mRNA localization is translation dependent and is post-transcriptionally regulated by the CsrA-FliW network. Overall, our results suggest a role for CsrA-FliW in spatiotemporal control of flagella assembly and localization of a dual-function mRNA.
Collapse
|
17
|
Abstract
Escherichia colicauses three types of illnesses in humans: diarrhea, urinary tract infections, and meningitis in newborns. The acquisition of virulence-associated genes and the ability to properly regulate these, often horizontally transferred, loci distinguishes pathogens from the normally harmless commensal E. coli found within the human intestine. This review addresses our current understanding of virulence gene regulation in several important diarrhea-causing pathotypes, including enteropathogenic, enterohemorrhagic,enterotoxigenic, and enteroaggregativeE. coli-EPEC, EHEC, ETEC and EAEC, respectively. The intensely studied regulatory circuitry controlling virulence of uropathogenicE. coli, or UPEC, is also reviewed, as is that of MNEC, a common cause of meningitis in neonates. Specific topics covered include the regulation of initial attachment events necessary for infection, environmental cues affecting virulence gene expression, control of attaching and effacing lesionformation, and control of effector molecule expression and secretion via the type III secretion systems by EPEC and EHEC. How phage control virulence and the expression of the Stx toxins of EHEC, phase variation, quorum sensing, and posttranscriptional regulation of virulence determinants are also addressed. A number of important virulence regulators are described, including the AraC-like molecules PerA of EPEC, CfaR and Rns of ETEC, and AggR of EAEC;the Ler protein of EPEC and EHEC;RfaH of UPEC;and the H-NS molecule that acts to silence gene expression. The regulatory circuitry controlling virulence of these greatly varied E. colipathotypes is complex, but common themes offerinsight into the signals and regulators necessary forE. coli disease progression.
Collapse
|
18
|
Mathematical model of flagella gene expression dynamics in Salmonella enterica serovar typhimurium. SYSTEMS AND SYNTHETIC BIOLOGY 2015; 9:19-31. [PMID: 25972986 DOI: 10.1007/s11693-015-9160-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Revised: 10/11/2014] [Accepted: 01/21/2015] [Indexed: 01/11/2023]
Abstract
Flagellar assembly in Salmonella is controlled by an intricate genetic and biochemical network. This network comprises of a number of inter-connected feedback loops, which control the assembly process dynamically. Critical among these are the FliA-FlgM feedback, FliZ-mediated positive feedback, and FliT-mediated negative feedback. In this work, we develop a mathematical model to track the dynamics of flagellar gene expression in Salmonella. Analysis of our model demonstrates that the network is wired to not only control the transition of the cell from a non-flagellated to a flagellated state, but to also control dynamics of gene expression during cell division. Further, we predict that FliZ encoded in the flagellar regulon acts as a critical secretion-dependent molecular link between flagella and Salmonella Pathogenicity Island 1 gene expression. Sensitivity analysis of the model demonstrates that the flagellar regulatory network architecture is extremely robust to mutations.
Collapse
|
19
|
Singer HM, Erhardt M, Hughes KT. Comparative analysis of the secretion capability of early and late flagellar type III secretion substrates. Mol Microbiol 2014; 93:505-20. [PMID: 24946091 DOI: 10.1111/mmi.12675] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/13/2014] [Indexed: 11/28/2022]
Abstract
A remarkable feature of the flagellar-specific type III secretion system (T3SS) is the selective recognition of a few substrate proteins among the many thousand cytoplasmic proteins. Secretion substrates are divided into two specificity classes: early substrates secreted for hook-basal body (HBB) construction and late substrates secreted after HBB completion. Secretion was reported to require a disordered N-terminal secretion signal, mRNA secretion signals within the 5'-untranslated region (5'-UTR) and for late substrates, piloting proteins known as the T3S chaperones. Here, we utilized translational β-lactamase fusions to probe the secretion efficacy of the N-terminal secretion signal of fourteen secreted flagellar substrates in Salmonella enterica. We observed a surprising variety in secretion capability between flagellar proteins of the same secretory class. The peptide secretion signals of the early-type substrates FlgD, FlgF, FlgE and the late-type substrate FlgL were analysed in detail. Analysing the role of the 5'-UTR in secretion of flgB and flgE revealed that the native 5'-UTR substantially enhanced protein translation and secretion. Based on our data, we propose a multicomponent signal that drives secretion via the flagellar T3SS. Both mRNA and peptide signals are recognized by the export apparatus and together with substrate-specific chaperones allowing for targeted secretion of flagellar substrates.
Collapse
Affiliation(s)
- Hanna M Singer
- Microbiologie, Département de Médecine, Université de Fribourg, Fribourg, Switzerland
| | | | | |
Collapse
|
20
|
Abstract
The assembly of the bacterial flagellum is exquisitely controlled. Flagellar biosynthesis is underpinned by a specialized type III secretion system that allows export of proteins from the cytoplasm to the nascent structure. Bacillus subtilis regulates flagellar assembly using both conserved and species-specific mechanisms. Here, we show that YvyG is essential for flagellar filament assembly. We define YvyG as an orthologue of the Salmonella enterica serovar Typhimurium type III secretion system chaperone, FlgN, which is required for the export of the hook-filament junction proteins, FlgK and FlgL. Deletion of flgN (yvyG) results in a nonmotile phenotype that is attributable to a decrease in hag translation and a complete lack of filament polymerization. Analyses indicate that a flgK-flgL double mutant strain phenocopies deletion of flgN and that overexpression of flgK-flgL cannot complement the motility defect of a ΔflgN strain. Furthermore, in contrast to previous work suggesting that phosphorylation of FlgN alters its subcellular localization, we show that mutation of the identified tyrosine and arginine FlgN phosphorylation sites has no effect on motility. These data emphasize that flagellar biosynthesis is differentially regulated in B. subtilis from classically studied Gram-negative flagellar systems and questions the biological relevance of some posttranslational modifications identified by global proteomic approaches.
Collapse
|
21
|
Analysis of factors that affect FlgM-dependent type III secretion for protein purification with Salmonella enterica serovar Typhimurium. J Bacteriol 2014; 196:2333-47. [PMID: 24706743 DOI: 10.1128/jb.01572-14] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The FlgM protein is secreted in response to flagellar hook-basal body secretion and can be used as a secretion signal to direct selected protein secretion via the flagellar type III secretion (T3S) system [H. M. Singer, M. Erhardt, A. M. Steiner, M. M. Zhang, D. Yoshikami, G. Bulaj, B. M. Olivera, and K. T. Hughes, mBio 3(3):e00115-12, 2012, http://dx.doi.org/10.1128/mBio.00115-12]. Conditions known to affect flagellar gene expression, FlgM stability, and flagellar T3S were tested either alone or in combination to determine their effects on levels of secreted FlgM. These conditions included mutations that affect activity of the flagellar FlhD4C2 master regulatory protein complex or the FlgM T3S chaperone σ(28), the removal of Salmonella pathogenicity island 1 (Spi1), the removal of flagellar late secretion substrates that could compete with FlgM for secretion, and changes in the ionic strength of the growth medium. Conditions that enhanced FlgM secretion were combined in order to maximize levels of secreted FlgM. An optimized FlgM secretion strain was used to secrete and isolate otherwise difficult-to-produce proteins and peptides fused to the C terminus of FlgM. These include cysteine-rich, hydrophobic peptides (conotoxins δ-SVIE and MrVIA), nodule-specific, cysteine-rich antimicrobial peptides (NCR), and a malaria surface antigen domain of apical membrane antigen AMA-1.
Collapse
|
22
|
Xu S, Peng Z, Cui B, Wang T, Song Y, Zhang L, Wei G, Wang Y, Shen X. FliS modulates FlgM activity by acting as a non-canonical chaperone to control late flagellar gene expression, motility and biofilm formation in Yersinia pseudotuberculosis. Environ Microbiol 2013; 16:1090-104. [PMID: 23957589 DOI: 10.1111/1462-2920.12222] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Accepted: 07/19/2013] [Indexed: 12/01/2022]
Abstract
The FlgM-FliA regulatory circuit plays a central role in coordinating bacterial flagellar assembly. In this study, we identified multiple novel binding partners of FlgM using bacterial two-hybrid screening. Among these binding partners, FliS, the secretion chaperone of the filament protein FliC, was identified to compete with FliA for the binding of FlgM. We further showed that by binding to FlgM, FliS protects it from secretion and degradation, thus maintaining an intracellular pool of FlgM reserved as the FliS-FlgM complex. Consequently, we found that the flagellar late-class promoter activities are significantly increased in the fliS deletion mutant. The fliS mutant is weakly motile and shows significantly increased biofilm formation on biotic surface. Based on the results obtained, we established for the first time the regulatory role of the flagellin chaperone FliS to fine-tune late flagellar assembly by modulating FlgM activity.
Collapse
Affiliation(s)
- Shengjuan Xu
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, 712100, China; Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, 430071, China
| | | | | | | | | | | | | | | | | |
Collapse
|
23
|
RflM functions as a transcriptional repressor in the autogenous control of the Salmonella Flagellar master operon flhDC. J Bacteriol 2013; 195:4274-82. [PMID: 23873910 DOI: 10.1128/jb.00728-13] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Motility of bacteria like Salmonella enterica is a highly regulated process that responds to a variety of internal and external stimuli. A hierarchy of three promoter classes characterizes the Salmonella flagellar system, and the onset of flagellar gene expression depends on the oligomeric regulatory complex and class 1 gene product FlhD(4)C(2). The flhDC promoter is a target for a broad range of transcriptional regulators that bind within the flhDC promoter region and either negatively or positively regulate flhDC operon transcription. In this work, we demonstrate that the RflM protein is a key component of flhDC regulation. Transposon mutagenesis was performed to investigate a previously described autoinhibitory effect of the flagellar master regulatory complex FlhD(4)C(2). RflM is a LuxR homolog that functions as a flagellar class 1 transcriptional repressor. RflM was found to be the negative regulator of flhDC expression that is responsible for the formerly described autoinhibitory effect of the FlhD(4)C(2) complex on flhDC operon transcription (K. Kutsukake, Mol. Gen. Genet. 254:440-448, 1997). We conclude that upon commencement of flagellar gene expression, the FlhD(4)C(2) complex initiates a regulatory feedback loop by activating rflM gene expression. rflM encodes a transcriptional repressor, RflM, which fine-tunes flhDC expression levels.
Collapse
|
24
|
Heel T, Vogel GF, Lammirato A, Schneider R, Auer B. FlgM as a secretion moiety for the development of an inducible type III secretion system. PLoS One 2013; 8:e59034. [PMID: 23554966 PMCID: PMC3595227 DOI: 10.1371/journal.pone.0059034] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Accepted: 02/11/2013] [Indexed: 11/18/2022] Open
Abstract
Regulation and assembly of the flagellar type III secretion system is one of the most investigated and best understood regulational cascades in molecular biology. Depending on the host organism, flagellar morphogenesis requires the interplay of more than 50 genes. Direct secretion of heterologous proteins to the supernatant is appealing due to protection against cellular proteases and simplified downstream processing. As Escherichia coli currently remains the predominant host organism used for recombinant prokaryotic protein expression, the generation of a strain that exhibits inducible flagellar secretion would be highly desirable for biotechnological applications. Here, we report the first engineered Escherichia coli mutant strain featuring flagellar morphogenesis upon addition of an external inducer. Using FlgM as a sensor for direct secretion in combination with this novel strain may represent a potent tool for significant improvements in future engineering of an inducible type III secretion for heterologous proteins.
Collapse
Affiliation(s)
- Thomas Heel
- Institute of Biochemistry, University of Innsbruck, Innsbruck, Austria.
| | | | | | | | | |
Collapse
|
25
|
Protein export according to schedule: architecture, assembly, and regulation of type III secretion systems from plant- and animal-pathogenic bacteria. Microbiol Mol Biol Rev 2012; 76:262-310. [PMID: 22688814 DOI: 10.1128/mmbr.05017-11] [Citation(s) in RCA: 299] [Impact Index Per Article: 24.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Flagellar and translocation-associated type III secretion (T3S) systems are present in most gram-negative plant- and animal-pathogenic bacteria and are often essential for bacterial motility or pathogenicity. The architectures of the complex membrane-spanning secretion apparatuses of both systems are similar, but they are associated with different extracellular appendages, including the flagellar hook and filament or the needle/pilus structures of translocation-associated T3S systems. The needle/pilus is connected to a bacterial translocon that is inserted into the host plasma membrane and mediates the transkingdom transport of bacterial effector proteins into eukaryotic cells. During the last 3 to 5 years, significant progress has been made in the characterization of membrane-associated core components and extracellular structures of T3S systems. Furthermore, transcriptional and posttranscriptional regulators that control T3S gene expression and substrate specificity have been described. Given the architecture of the T3S system, it is assumed that extracellular components of the secretion apparatus are secreted prior to effector proteins, suggesting that there is a hierarchy in T3S. The aim of this review is to summarize our current knowledge of T3S system components and associated control proteins from both plant- and animal-pathogenic bacteria.
Collapse
|
26
|
Minamino T, Kinoshita M, Hara N, Takeuchi S, Hida A, Koya S, Glenwright H, Imada K, Aldridge PD, Namba K. Interaction of a bacterial flagellar chaperone FlgN with FlhA is required for efficient export of its cognate substrates. Mol Microbiol 2012; 83:775-88. [DOI: 10.1111/j.1365-2958.2011.07964.x] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
27
|
Impact of the N-terminal secretor domain on YopD translocator function in Yersinia pseudotuberculosis type III secretion. J Bacteriol 2011; 193:6683-700. [PMID: 21965570 DOI: 10.1128/jb.00210-11] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Type III secretion systems (T3SSs) secrete needle components, pore-forming translocators, and the translocated effectors. In part, effector recognition by a T3SS involves their N-terminal amino acids and their 5' mRNA. To investigate whether similar molecular constraints influence translocator secretion, we scrutinized this region within YopD from Yersinia pseudotuberculosis. Mutations in the 5' end of yopD that resulted in specific disruption of the mRNA sequence did not affect YopD secretion. On the other hand, a few mutations affecting the protein sequence reduced secretion. Translational reporter fusions identified the first five codons as a minimal N-terminal secretion signal and also indicated that the YopD N terminus might be important for yopD translation control. Hybrid proteins in which the N terminus of YopD was exchanged with the equivalent region of the YopE effector or the YopB translocator were also constructed. While the in vitro secretion profile was unaltered, these modified bacteria were all compromised with respect to T3SS activity in the presence of immune cells. Thus, the YopD N terminus does harbor a secretion signal that may also incorporate mechanisms of yopD translation control. This signal tolerates a high degree of variation while still maintaining secretion competence suggestive of inherent structural peculiarities that make it distinct from secretion signals of other T3SS substrates.
Collapse
|
28
|
Crhanova M, Malcova M, Mazgajova M, Karasova D, Sebkova A, Fucikova A, Bortlicek Z, Pilousova L, Kyrova K, Dekanova M, Rychlik I. LPS structure influences protein secretion in Salmonella enterica. Vet Microbiol 2011; 152:131-7. [PMID: 21570779 DOI: 10.1016/j.vetmic.2011.04.018] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2010] [Revised: 04/09/2011] [Accepted: 04/14/2011] [Indexed: 12/14/2022]
Abstract
In this study we have compared protein secretion in the wild type of S. Typhimurium and the rfaC mutant. We found out that the rfaC mutant was defective in protein secretion. In addition, the rfaC mutant was defective in its invasion into an IPEC-J2 porcine epithelial cell line and also in motility in semisolid agar. Consistent with this, reduced flagella numbers were observed in the rfaC mutant. In the rfaC mutant, there were no defects in flagellin expression as detected by western blot and immune electron microscopy which demonstrated equal amounts of flagellin in the cytoplasm of both the rfaC mutant and the wild-type S. Typhimurium. However, in the wild-type strain only, the flagellin was assembled to spatially restricted areas on the inner side of cytoplasmic membrane. The oligosaccharide core of LPS is therefore required for the assembly of flagella and T3SS secretion machinery followed by protein secretion.
Collapse
Affiliation(s)
- M Crhanova
- Veterinary Research Institute, Hudcova 70, 621 00 Brno, Czech Republic
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
29
|
Saini S, Floess E, Aldridge C, Brown J, Aldridge PD, Rao CV. Continuous control of flagellar gene expression by the σ28-FlgM regulatory circuit in Salmonella enterica. Mol Microbiol 2010; 79:264-78. [PMID: 21166907 DOI: 10.1111/j.1365-2958.2010.07444.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
The flagellar genes in Salmonella enterica are expressed in a temporal hierarchy that mirrors the assembly process itself. The σ(28)-FlgM regulatory circuit plays a key role in controlling this temporal hierarchy. This circuit ensures that the class 3 genes are expressed only when the hook-basal body (HBB), a key intermediate in flagellar assembly, is complete. In this work, we investigated the role of the σ(28)-FlgM regulatory circuit in controlling the timing and magnitude of class 3 gene expression using a combination of mathematical modelling and experimental analysis. Analysis of the model predicted that this circuit continuously controls class 3 gene expression in response to HBB abundance. We experimentally validated these predictions by eliminating different components of the σ(28)-FlgM regulatory system and also by rewiring the transcriptional hierarchy. Based on these results, we conclude that the σ(28)-FlgM regulatory circuit continuously senses the HBB assembly process and regulates class 3 gene expression and possibly flagellar numbers in response.
Collapse
Affiliation(s)
- Supreet Saini
- Department of Chemical & Biomolecular Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA
| | | | | | | | | | | |
Collapse
|
30
|
Abstract
FliZ is an activator of class 2 flagellar gene expression in Salmonella enterica. To understand its role in flagellar assembly, we investigated how FliZ affects gene expression dynamics. We demonstrate that FliZ participates in a positive-feedback loop that induces a kinetic switch in class 2 gene expression.
Collapse
|
31
|
Multiple promoters contribute to swarming and the coordination of transcription with flagellar assembly in Salmonella. J Bacteriol 2010; 192:4752-62. [PMID: 20639318 DOI: 10.1128/jb.00093-10] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In Salmonella, there are three classes of promoters in the flagellar transcriptional hierarchy. This organization allows genes needed earlier in the construction of flagella to be transcribed before genes needed later. Four operons (fliAZY, flgMN, fliDST, and flgKL) are expressed from both class 2 and class 3 promoters. To investigate the purpose for expressing genes from multiple flagellar promoters, mutants were constructed for each operon that were defective in either class 2 transcription or class 3 transcription. The mutants were checked for defects in swimming through liquids, swarming over surfaces, and transcriptional regulation. The expression of the hook-associated proteins (FlgK, FlgL, and FliD) from class 3 promoters was found to be important for swarming motility. Both flgMN promoters were involved in coordinating class 3 transcription with the stage of assembly of the hook-basal body. Finally, the fliAZY class 3 promoter lowered class 3 transcription in stationary phase. These results indicate that the multiple flagellar promoters respond to specific environmental conditions and help coordinate transcription with flagellar assembly.
Collapse
|
32
|
Structural insight into the regulatory mechanisms of interactions of the flagellar type III chaperone FliT with its binding partners. Proc Natl Acad Sci U S A 2010; 107:8812-7. [PMID: 20421493 DOI: 10.1073/pnas.1001866107] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
For self-assembly of the bacterial flagellum, most of the flagellar component proteins synthesized in the cytoplasm are exported by the flagellar type III export apparatus to the growing, distal end. Flagellar protein export is highly organized and well controlled in every step of the flagellar assembly process. Flagellar-specific chaperones not only facilitate the export of their cognate proteins, as well as prevent their premature aggregation in the cytoplasm, but also play a role in fine-tuning flagellar gene expression to be coupled with the flagellar assembly process. FliT is a flagellar-specific chaperone responsible for the export of the filament-capping protein FliD and for negative control of flagellar gene expression by binding to the FlhDC complex. Here we report the crystal structure of Salmonella FliT at 3.2-A resolution. The structural and biochemical analyses clearly reveal that the C-terminal segment of FliT regulates its interactions with the FlhDC complex, FliI ATPase, and FliJ (subunits of the export apparatus), and that its conformational change is responsible for the switch in its binding partners during flagellar protein export.
Collapse
|
33
|
Tree JJ, Wolfson EB, Wang D, Roe AJ, Gally DL. Controlling injection: regulation of type III secretion in enterohaemorrhagic Escherichia coli. Trends Microbiol 2009; 17:361-70. [PMID: 19660954 DOI: 10.1016/j.tim.2009.06.001] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2008] [Revised: 05/25/2009] [Accepted: 06/01/2009] [Indexed: 12/01/2022]
Abstract
Type III secretion (T3S) systems enable the injection of bacterial proteins through membrane barriers into host cells, either from outside the host cell or from within a vacuole. This system is required for colonization of their ruminant reservoir hosts by enterohaemorrhagic Escherichia coli (EHEC) and might also be important for the etiology of disease in the incidental human host. T3S systems of E. coli inject a cocktail of proteins into epithelial cells that enables bacterial attachment and promotes longer-term colonization in the animal. Here, we review recent progress in our understanding of the regulation of T3S in EHEC, focusing on the induction and assembly of the T3S system, the co-ordination of effector protein expression, and the timing of effector protein export through the apparatus. Strain variation is often associated with differences in bacteriophages encoding the production of Shiga toxin and in multiple cryptic prophage elements that can encode effector proteins and T3S regulators. It is evident that this repertoire of phage-related sequences results in the different levels of T3S demonstrated between strains, with implications for EHEC epidemiology and strain evolution.
Collapse
Affiliation(s)
- Jai J Tree
- Immunity and Infection Division, The Roslin Institute and R(D)SVS, Chancellor's Building, University of Edinburgh, Edinburgh, EH16 4SB, UK
| | | | | | | | | |
Collapse
|
34
|
Perkins TT, Kingsley RA, Fookes MC, Gardner PP, James KD, Yu L, Assefa SA, He M, Croucher NJ, Pickard DJ, Maskell DJ, Parkhill J, Choudhary J, Thomson NR, Dougan G. A strand-specific RNA-Seq analysis of the transcriptome of the typhoid bacillus Salmonella typhi. PLoS Genet 2009; 5:e1000569. [PMID: 19609351 PMCID: PMC2704369 DOI: 10.1371/journal.pgen.1000569] [Citation(s) in RCA: 170] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2009] [Accepted: 06/19/2009] [Indexed: 12/23/2022] Open
Abstract
High-density, strand-specific cDNA sequencing (ssRNA-seq) was used to analyze the transcriptome of Salmonella enterica serovar Typhi (S. Typhi). By mapping sequence data to the entire S. Typhi genome, we analyzed the transcriptome in a strand-specific manner and further defined transcribed regions encoded within prophages, pseudogenes, previously un-annotated, and 3'- or 5'-untranslated regions (UTR). An additional 40 novel candidate non-coding RNAs were identified beyond those previously annotated. Proteomic analysis was combined with transcriptome data to confirm and refine the annotation of a number of hpothetical genes. ssRNA-seq was also combined with microarray and proteome analysis to further define the S. Typhi OmpR regulon and identify novel OmpR regulated transcripts. Thus, ssRNA-seq provides a novel and powerful approach to the characterization of the bacterial transcriptome.
Collapse
Affiliation(s)
- Timothy T. Perkins
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Robert A. Kingsley
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Maria C. Fookes
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Paul P. Gardner
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Keith D. James
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Lu Yu
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Samuel A. Assefa
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Miao He
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Nicholas J. Croucher
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Derek J. Pickard
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Duncan J. Maskell
- Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Julian Parkhill
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Jyoti Choudhary
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Nicholas R. Thomson
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
| | - Gordon Dougan
- Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, United Kingdom
| |
Collapse
|
35
|
The Helicobacter pylori anti-sigma factor FlgM is predominantly cytoplasmic and cooperates with the flagellar basal body protein FlhA. J Bacteriol 2009; 191:4824-34. [PMID: 19465658 DOI: 10.1128/jb.00018-09] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Helicobacter pylori requires flagellar motility and orientation to persist actively in its habitat. A particular feature of flagella in most Helicobacter species including H. pylori is a membraneous flagellar sheath. The anti-sigma factor FlgM of H. pylori is unusual, since it lacks an N-terminal domain present in other FlgM homologs, e.g., FlgM of Salmonella spp., whose regulatory function is intimately coupled to its secretion through the flagellar type III secretion system. The aim of the present study was to characterize the localization and secretion of the short H. pylori FlgM in the presence of a flagellar sheath and to elucidate its interaction with other flagellar proteins, such as the basal body protein FlhA, which was previously shown to cooperate with FlgM for regulation. H. pylori FlgM was only released into the medium in minor amounts in wild-type bacteria, where the bulk amount of the protein was retained in the cytoplasm. Some FlgM was detected in the flagellar fraction. FlgM was expressed in flhA mutants and was less soluble and differentially localized in bacterial fractions of the flhA mutant in comparison to wild-type bacteria. FlgM-green fluorescent protein and FlgM-V5 translational fusions were generated and expressed in H. pylori. FlgM displayed a predominantly polar distribution and interacted with the C-terminal domain of FlhA (FlhA(C)). We suggest that, in H. pylori, FlgM secretion may not be paramount for its regulatory function and that protein interactions at the flagellar basal body may determine the turnover and localization of functional FlgM.
Collapse
|
36
|
Impact of inactivated extracellular proteases on the modified flagellin type III secretion pathway of Bacillus halodurans. Appl Environ Microbiol 2008; 75:271-4. [PMID: 18997028 DOI: 10.1128/aem.02430-08] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The flagellin type III secretion pathway of Bacillus halodurans BhFC01 (Deltahag) was modified by the inactivation of fliD. An in-frame flagellin gene fusion polypeptide construct was expressed, and the heterologous peptides were secreted as flagellin fusion monomers. The stability of the secreted monomers was significantly enhanced through gene-targeted inactivation of extracellular proteases.
Collapse
|
37
|
Brown JD, Saini S, Aldridge C, Herbert J, Rao CV, Aldridge PD. The rate of protein secretion dictates the temporal dynamics of flagellar gene expression. Mol Microbiol 2008; 70:924-37. [PMID: 18811728 DOI: 10.1111/j.1365-2958.2008.06455.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Flagellar gene expression is temporally regulated in response to the assembly state of the growing flagellum. The key mechanism for enforcing this temporal hierarchy in Salmonella enterica serovar Typhimurium is the sigma(28)-FlgM checkpoint, which couples the expression of the late flagellar (P(class3)) genes to the completion of the hook-basal body. This checkpoint is triggered when FlgM is secreted from the cell. In addition to the sigma(28)-FlgM checkpoint, a number of other regulatory mechanisms respond to the secretion of late proteins. In this work, we examined how middle (P(class2)) and late (P(class3)) gene expression is affected by late protein secretion. Dynamic analysis of flagellar gene expression identified a novel mechanism where induction of P(class2) activity is delayed either when late protein secretion is abolished or when late protein secretion is increased. Using a number of different approaches, we were able to show that this mechanism did not involve any known flagellar regulator. Furthermore, the changes in P(class2) activity were not correlated with the associated changes in P(class3) activity, which was found to be proportional to late protein secretion rates. Our data indicate that both P(class2) and P(class3) promoters are continuously regulated in response to assembly and late protein secretion rates. These results suggest that flagellar regulation is more complex than previously thought.
Collapse
Affiliation(s)
- Jonathon D Brown
- Centre for Bacterial Cell Biology, Newcastle University, Framlington Place, Newcastle upon Tyne, UK
| | | | | | | | | | | |
Collapse
|
38
|
Chevance FFV, Hughes KT. Coordinating assembly of a bacterial macromolecular machine. Nat Rev Microbiol 2008; 6:455-65. [PMID: 18483484 DOI: 10.1038/nrmicro1887] [Citation(s) in RCA: 513] [Impact Index Per Article: 32.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The assembly of large and complex organelles, such as the bacterial flagellum, poses the formidable problem of coupling temporal gene expression to specific stages of the organelle-assembly process. The discovery that levels of the bacterial flagellar regulatory protein FlgM are controlled by its secretion from the cell in response to the completion of an intermediate flagellar structure (the hook-basal body) was only the first of several discoveries of unique mechanisms that coordinate flagellar gene expression with assembly. In this Review, we discuss this mechanism, together with others that also coordinate gene regulation and flagellar assembly in Gram-negative bacteria.
Collapse
Affiliation(s)
- Fabienne F V Chevance
- Department of Biology, University of Utah, 257 South 1400 East, Salt Lake City, Utah 84112, USA
| | | |
Collapse
|
39
|
Chevance FFV, Hughes KT. Coordinating assembly of a bacterial macromolecular machine. NATURE REVIEWS. MICROBIOLOGY 2008. [PMID: 18483484 DOI: 10.1038/nrmicro1887.] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The assembly of large and complex organelles, such as the bacterial flagellum, poses the formidable problem of coupling temporal gene expression to specific stages of the organelle-assembly process. The discovery that levels of the bacterial flagellar regulatory protein FlgM are controlled by its secretion from the cell in response to the completion of an intermediate flagellar structure (the hook-basal body) was only the first of several discoveries of unique mechanisms that coordinate flagellar gene expression with assembly. In this Review, we discuss this mechanism, together with others that also coordinate gene regulation and flagellar assembly in Gram-negative bacteria.
Collapse
Affiliation(s)
- Fabienne F V Chevance
- Department of Biology, University of Utah, 257 South 1400 East, Salt Lake City, Utah 84112, USA
| | | |
Collapse
|
40
|
FliZ Is a posttranslational activator of FlhD4C2-dependent flagellar gene expression. J Bacteriol 2008; 190:4979-88. [PMID: 18469103 DOI: 10.1128/jb.01996-07] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Flagellar assembly proceeds in a sequential manner, beginning at the base and concluding with the filament. A critical aspect of assembly is that gene expression is coupled to assembly. When cells transition from a nonflagellated to a flagellated state, gene expression is sequential, reflecting the manner in which the flagellum is made. A key mechanism for establishing this temporal hierarchy is the sigma(28)-FlgM checkpoint, which couples the expression of late flagellar (P(class3)) genes to the completion of the hook-basal body. In this work, we investigated the role of FliZ in coupling middle flagellar (P(class2)) gene expression to assembly in Salmonella enterica serovar Typhimurium. We demonstrate that FliZ is an FlhD(4)C(2)-dependent activator of P(class2)/middle gene expression. Our results suggest that FliZ regulates the concentration of FlhD(4)C(2) posttranslationally. We also demonstrate that FliZ functions independently of the flagellum-specific sigma factor sigma(28) and the filament-cap chaperone/FlhD(4)C(2) inhibitor FliT. Furthermore, we show that the previously described ability of sigma(28) to activate P(class2)/middle gene expression is, in fact, due to FliZ, as both are expressed from the same overlapping P(class2) and P(class3) promoters at the fliAZY locus. We conclude by discussing the role of FliZ regulation with respect to flagellar biosynthesis based on our characterization of gene expression and FliZ's role in swimming and swarming motility.
Collapse
|
41
|
Riordan KE, Schneewind O. YscU cleavage and the assembly of Yersinia type III secretion machine complexes. Mol Microbiol 2008; 68:1485-501. [PMID: 18452514 DOI: 10.1111/j.1365-2958.2008.06247.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
YscU, a component of the Yersinia type III secretion machine, promotes auto-cleavage at asparagine 263 (N263). Mutants with an alanine substitution at yscU codon 263 displayed secretion defects for some substrates (LcrV, YopB and YopD); however, transport of effector proteins into host cells (YopE, YopH, YopM) continued to occur. Two yscU mutations were isolated that, unlike N263A, completely abolished type III secretion; YscU(G127D) promoted auto-cleavage at N263, whereas YscU(G270N) did not. When fused to glutathione S-transferase (Gst), the YscU C-terminal cytoplasmic domain promoted auto-cleavage and Gst-YscU(C) also exerted a dominant-negative phenotype by blocking type III secretion. Gst-YscU(C/N263A) caused a similar blockade and Gst-YscU(C/G270N) reduced secretion. Gst-YscU(C) and Gst-YscU(C/N263A) bound YscL, the regulator of the ATPase YscN, whereas Gst-YscU(C/G270N) did not. When isolated from Yersinia, Gst-YscU(C) and Gst-YscU(C/N263A) associated with YscK-YscL-YscQ; however, Gst-YscU(C/G270N) interacted predominantly with the machine component YscO, but not with YscK-YscL-YscQ. A model is proposed whereby YscU auto-cleavage promotes interaction with YscL and recruitment of ATPase complexes that initiate type III secretion.
Collapse
Affiliation(s)
- Kelly E Riordan
- Department of Microbiology, University of Chicago, Chicago, IL 60637, USA
| | | |
Collapse
|
42
|
Brutinel ED, Yahr TL. Control of gene expression by type III secretory activity. Curr Opin Microbiol 2008; 11:128-33. [PMID: 18396449 DOI: 10.1016/j.mib.2008.02.010] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2008] [Revised: 02/04/2008] [Accepted: 02/21/2008] [Indexed: 12/28/2022]
Abstract
The bacterial flagellum and the highly related injectisome (or needle complex) are among the most complicated multi-protein structures found in Gram-negative microorganisms. The assembly of both structures is dependent upon a type III secretion system. An interesting regulatory feature unique to these systems is the coordination of gene expression with type III secretory activity. This means of regulation ensures that secretion substrates are expressed only when required during the assembly process or upon completion of the fully functional structure. Prominent within the regulatory scheme are secreted proteins and type III secretion chaperones that exert effects on gene expression at the transcriptional and post-transcriptional levels. Although the major structural components of the flagellum and injectisome systems are highly conserved, recent studies reveal diversity in the mechanisms used by secretion substrates and chaperones to control gene expression.
Collapse
Affiliation(s)
- Evan D Brutinel
- Department of Microbiology, University of Iowa, 540B Eckstein Medical Research Building, Iowa City, IA 52242-1101, USA.
| | | |
Collapse
|
43
|
Norris V, den Blaauwen T, Doi RH, Harshey RM, Janniere L, Jiménez-Sánchez A, Jin DJ, Levin PA, Mileykovskaya E, Minsky A, Misevic G, Ripoll C, Saier M, Skarstad K, Thellier M. Toward a hyperstructure taxonomy. Annu Rev Microbiol 2007; 61:309-29. [PMID: 17896876 DOI: 10.1146/annurev.micro.61.081606.103348] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Bacterial cells contain many large, spatially extended assemblies of ions, molecules, and macromolecules, called hyperstructures, that are implicated in functions that range from DNA replication and cell division to chemotaxis and secretion. Interactions between these hyperstructures would create a level of organization intermediate between macromolecules and the cell itself. To explore this level, a taxonomy is needed. Here, we describe classification criteria based on the form of the hyperstructure and on the processes responsible for this form. These processes include those dependent on coupled transcription-translation, protein-protein affinities, chromosome site-binding by protein, and membrane structures. Various combinations of processes determine the formation, maturation, and demise of many hyperstructures that therefore follow a trajectory within the space of classification by form/process. Hence a taxonomy by trajectory may be desirable. Finally, we suggest that working toward a taxonomy based on speculative interactions between hyperstructures promises most insight into life at this level.
Collapse
Affiliation(s)
- Vic Norris
- Department of Science, University of Rouen, 76821 Mont Saint Aignan Cedex, France.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
44
|
Norris V, den Blaauwen T, Cabin-Flaman A, Doi RH, Harshey R, Janniere L, Jimenez-Sanchez A, Jin DJ, Levin PA, Mileykovskaya E, Minsky A, Saier M, Skarstad K. Functional taxonomy of bacterial hyperstructures. Microbiol Mol Biol Rev 2007; 71:230-53. [PMID: 17347523 PMCID: PMC1847379 DOI: 10.1128/mmbr.00035-06] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The levels of organization that exist in bacteria extend from macromolecules to populations. Evidence that there is also a level of organization intermediate between the macromolecule and the bacterial cell is accumulating. This is the level of hyperstructures. Here, we review a variety of spatially extended structures, complexes, and assemblies that might be termed hyperstructures. These include ribosomal or "nucleolar" hyperstructures; transertion hyperstructures; putative phosphotransferase system and glycolytic hyperstructures; chemosignaling and flagellar hyperstructures; DNA repair hyperstructures; cytoskeletal hyperstructures based on EF-Tu, FtsZ, and MreB; and cell cycle hyperstructures responsible for DNA replication, sequestration of newly replicated origins, segregation, compaction, and division. We propose principles for classifying these hyperstructures and finally illustrate how thinking in terms of hyperstructures may lead to a different vision of the bacterial cell.
Collapse
Affiliation(s)
- Vic Norris
- Department of Science, University of Rouen, 76821 Mont Saint Aignan Cedex, France.
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
45
|
Mellies JL, Barron AMS, Carmona AM. Enteropathogenic and enterohemorrhagic Escherichia coli virulence gene regulation. Infect Immun 2007; 75:4199-210. [PMID: 17576759 PMCID: PMC1951183 DOI: 10.1128/iai.01927-06] [Citation(s) in RCA: 166] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Affiliation(s)
- Jay L Mellies
- Biology Department, Reed College, 3203 S.E. Woodstock Boulevard, Portland, OR 97202, USA.
| | | | | |
Collapse
|
46
|
Zhao K, Liu M, Burgess RR. Adaptation in bacterial flagellar and motility systems: from regulon members to 'foraging'-like behavior in E. coli. Nucleic Acids Res 2007; 35:4441-52. [PMID: 17576668 PMCID: PMC1935009 DOI: 10.1093/nar/gkm456] [Citation(s) in RCA: 126] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Bacterial flagellar motility and chemotaxis help cells to reach the most favorable environments and to successfully compete with other micro-organisms in response to external stimuli. Escherichia coli is a motile gram-negative bacterium, and the flagellar regulon in E. coli is controlled by a master regulator FlhDC as well as a second regulator, flagellum-specific sigma factor, σF. To define the physiological role of these two regulators, we carried out transcription profiling experiments to identify, on a genome-wide basis, genes under the control of these two regulators. In addition, the synchronized pattern of increasing CRP activity causing increasing FlhDC expression with decreasing carbon source quality, together with the apparent coupling of motility activity with the activation of motility and chemotaxis genes in poor quality carbon sources, highlights the importance of CRP activation in allowing E. coli to devote progressively more of its limited reserves to search out better conditions. In adaptation to a variety of carbon sources, the motile bacteria carry out tactical responses by increasing flagellar operation but restricting costly flagellar synthesis, indicating its capability of strategically using the precious energy in nutrient-poor environments for maximizing survival.
Collapse
Affiliation(s)
- Kai Zhao
- McArdle Laboratory for Cancer Research, Department of Genetics and Department of Computer Science, University of Wisconsin, Madison, WI 53706, USA
| | - Mingzhu Liu
- McArdle Laboratory for Cancer Research, Department of Genetics and Department of Computer Science, University of Wisconsin, Madison, WI 53706, USA
| | - Richard R. Burgess
- McArdle Laboratory for Cancer Research, Department of Genetics and Department of Computer Science, University of Wisconsin, Madison, WI 53706, USA
- *To whom correspondence should be addressed. +1-608-263-2635+1-608-262-2824
| |
Collapse
|
47
|
Sorg JA, Blaylock B, Schneewind O. Secretion signal recognition by YscN, the Yersinia type III secretion ATPase. Proc Natl Acad Sci U S A 2006; 103:16490-5. [PMID: 17050689 PMCID: PMC1637609 DOI: 10.1073/pnas.0605974103] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Yersinia type III machines secrete protein substrates across the bacterial envelope. Secretion signals of some substrates have been identified; however, the mechanisms whereby these signals interact with type III machines are not known. Here we show that fusion of YopR, an early secretion substrate, to the N terminus of dihydrofolate reductase (DHFR) or other tightly folded proteins generates impassable hybrids that cannot travel the type III pathway. YopR hybrids capture YscN, the ATPase that provides energy for type III transport reactions, in the bacterial cytoplasm. Eleven N-terminal residues function as the YopR secretion signal, which is required for both binding to YscN and blocking the type III pathway. When expressed during type III machine assembly, YopR-DHFR blocks all secretion. Delayed expression of YopR-DHFR, when yersiniae have already engaged the type III pathway, blocks secretion of early (YscP) but not of late (effector Yops) substrates. These observations support a model whereby type III machines are programmed to secrete a sequence of proteins that can be disrupted when an impassable early substrate interacts with the YscN ATPase and blocks the transport of late substrates.
Collapse
Affiliation(s)
- Joseph A. Sorg
- Department of Microbiology, University of Chicago, Chicago, IL 60637
| | - Bill Blaylock
- Department of Microbiology, University of Chicago, Chicago, IL 60637
| | - Olaf Schneewind
- Department of Microbiology, University of Chicago, Chicago, IL 60637
- *To whom correspondence should be addressed. E-mail:
| |
Collapse
|
48
|
Yamamoto S, Kutsukake K. FliT acts as an anti-FlhD2C2 factor in the transcriptional control of the flagellar regulon in Salmonella enterica serovar typhimurium. J Bacteriol 2006; 188:6703-8. [PMID: 16952964 PMCID: PMC1595477 DOI: 10.1128/jb.00799-06] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Flagellar operons are divided into three classes with respect to their transcriptional hierarchy in Salmonella enterica serovar Typhimurium. The class 1 gene products FlhD and FlhC act together in an FlhD(2)C(2) heterotetramer, which binds upstream of the class 2 promoters to facilitate binding of RNA polymerase. Class 2 expression is known to be enhanced by a disruption mutation in a flagellar gene, fliT. In this study, we purified FliT protein in a His-tagged form and showed that the protein prevented binding of FlhD(2)C(2) to the class 2 promoter and inhibited FlhD(2)C(2)-dependent transcription. Pull-down and far-Western blotting analyses revealed that the FliT protein was capable of binding to FlhD(2)C(2) and FlhC and not to FlhD alone. We conclude that FliT acts as an anti-FlhD(2)C(2) factor, which binds to FlhD(2)C(2) through interaction with the FlhC subunit and inhibits its binding to the class 2 promoter.
Collapse
Affiliation(s)
- Shouji Yamamoto
- Department of Biology, Faculty of Science, Okayama University, Tsushima-Naka 3-1-1, Okayama 700-8530, Japan
| | | |
Collapse
|
49
|
Aldridge PD, Karlinsey JE, Aldridge C, Birchall C, Thompson D, Yagasaki J, Hughes KT. The flagellar-specific transcription factor, sigma28, is the Type III secretion chaperone for the flagellar-specific anti-sigma28 factor FlgM. Genes Dev 2006; 20:2315-26. [PMID: 16912280 PMCID: PMC1553213 DOI: 10.1101/gad.380406] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The sigma(28) protein is a member of the bacterial sigma(70)-family of transcription factors that directs RNA polymerase to flagellar late (class 3) promoters. The sigma(28) protein is regulated in response to flagellar assembly by the anti-sigma(28) factor FlgM. FlgM inhibits sigma(28)-dependent transcription of genes whose products are needed late in assembly until the flagellar basal motor structure, the hook-basal body (HBB), is constructed. A second function for the sigma(28) transcription factor has been discovered: sigma(28) facilitates the secretion of FlgM through the HBB, acting as the FlgM Type III secretion chaperone. Transcription-specific mutants in sigma(28) were isolated that remained competent for FlgM-facilitated secretion separating the transcription and secretion-facilitation activities of sigma (28). Conversely, we also describe the isolation of mutants in sigma(28) that are specific for FlgM-facilitated secretion. The data demonstrate that sigma(28) is the Type III secretion chaperone for its own anti-sigma factor FlgM. Thus, a novel role for a sigma(70)-family transcription factor is described.
Collapse
Affiliation(s)
- Phillip D Aldridge
- Institute for Cell and Molecular Biosciences, Newcastle University, Framlington Place, Newcastle upon Tyne, NE2 4HH, UK.
| | | | | | | | | | | | | |
Collapse
|
50
|
Rosu V, Hughes KT. sigma28-dependent transcription in Salmonella enterica is independent of flagellar shearing. J Bacteriol 2006; 188:5196-203. [PMID: 16816191 PMCID: PMC1539944 DOI: 10.1128/jb.00299-06] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The FlgM anti-sigma28 factor is secreted in response to flagellar hook-basal body completion to allow sigma28-dependent transcription of genes needed late in flagellar assembly, such as the flagellin structural gene, fliC. A long-standing hypothesis was that one role of FlgM secretion was to allow rapid expression of flagellin in response to shearing. We tested this hypothesis by following FlgM secretion and fliC transcription in response to flagellar shearing. Experiments showed that the level of FlgM inside the cell was unchanged after shearing whereas the extracellular FlgM levels increased in the growth medium as time passed. Identical results were obtained with cells that were not exposed to shear forces: internal FlgM levels remained constant while external FlgM levels rose with time at rates similar to those for the sheared culture. Consistent with this find, FlgM/sigma28-dependent class 3 gene expression was unaffected by flagellar shearing but was affected by the growth phase of the cell. Regardless of exposure to shear forces, flagellar class 3 transcription rose sharply and then declined. These results demonstrate that flagellar regrowth following shearing is independent of FlgM secretion.
Collapse
Affiliation(s)
- Valentina Rosu
- Department of Biology, University of Utah, Salt Lake City, UT 84112, USA
| | | |
Collapse
|