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Das S, Das S, Rath PP, Banerjee A, Gourinath S, Mukhopadhyay AK, Maiti S. Hemolysin Coregulated Protein (HCP) from Vibrio Cholerae Interacts with the Host Cell Actin Cytoskeleton. ACS Infect Dis 2024; 10:2886-2898. [PMID: 39079033 DOI: 10.1021/acsinfecdis.4c00265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/10/2024]
Abstract
Vibrio cholerae (V. cholerae), the etiological agent of cholera, employs various virulence factors to adapt and thrive within both aquatic and human host environments. Among these factors, the type VI secretion system (T6SS) stands out as one of the crucial determinants of its pathogenicity. Valine glycine repeat protein G1 (VgrG1) and hemolysin coregulated protein (HCP) are considered major effector molecules of T6SS. Previous studies have highlighted that VgrG1 interacts with HCP proteins. Additionally, it has been shown that VgrG1 possesses an actin cross-linking domain (ACD) with actin-binding activity. Interestingly, it was reported that purified HCP protein treatment increased the stress fibers within cells. Therefore, we hypothesize that HCP may interact with host cell actin, potentially playing a role in the cytoskeletal rearrangement during V. cholerae infection. To test this hypothesis, we characterized HCP from the V. cholerae O139 serotype and demonstrated its interaction with actin monomers. In silico analysis and experimental validation revealed the presence of an actin-binding site within HCP. Furthermore, overexpression of HCP resulted in its colocalization with actin stress fibers in host cells. Our findings establish HCP as an effector molecule for potent host cell actin cytoskeleton remodeling during V. cholerae infection, providing new insights into bacterial pathogenicity mechanisms. Understanding the interplay between bacterial effectors and host cell components is crucial for developing targeted therapeutic interventions against cholera and related infectious diseases.
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Affiliation(s)
- Shubham Das
- Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Nadia, Mohanpur, West Bengal 741246, India
| | - Saikat Das
- Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Nadia, Mohanpur, West Bengal 741246, India
| | | | - Aishwarya Banerjee
- Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Nadia, Mohanpur, West Bengal 741246, India
| | - Samudrala Gourinath
- School of Life Sciences, Jawaharlal Nehru University, New Delhi 110067, India
| | | | - Sankar Maiti
- Department of Biological Sciences, Indian Institute of Science Education and Research Kolkata, Nadia, Mohanpur, West Bengal 741246, India
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Environmental Reservoirs of Pathogenic Vibrio spp. and Their Role in Disease: The List Keeps Expanding. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2023; 1404:99-126. [PMID: 36792873 DOI: 10.1007/978-3-031-22997-8_6] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/17/2023]
Abstract
Vibrio species are natural inhabitants of aquatic environments and have complex interactions with the environment that drive the evolution of traits contributing to their survival. These traits may also contribute to their ability to invade or colonize animal and human hosts. In this review, we attempt to summarize the relationships of Vibrio spp. with other organisms in the aquatic environment and discuss how these interactions could potentially impact colonization of animal and human hosts.
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Zwe YH, Yadav M, Zhen Ten MM, Srinivasan M, Jobichen C, Sivaraman J, Li D. Bacterial Antagonism of Chromobacterium haemolyticum and Characterization of its Putative Type VI Secretion System. Res Microbiol 2021; 173:103918. [PMID: 34906677 DOI: 10.1016/j.resmic.2021.103918] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 12/08/2021] [Accepted: 12/08/2021] [Indexed: 10/19/2022]
Abstract
This study reports the isolation of a new Chromobacterium haemolyticum strain named WI5 from a hydroponic farming facility. WI5 exhibited remarkable bacterial antagonistic properties, eliminating Salmonella, Escherichia coli, Listeria monocytogenes and Staphylococcus aureus (initial inoculum load ∼105 CFU/ml) in dual-species co-culture biofilms. Antagonism was strictly contact-dependent and highly influenced by nutrient availability. Next, we identified a complete suite of putative Type VI secretion system (T6SS) genes in the WI5 genome, annotated the gene locus architecture, and determined the crystal structure of hallmark T6SS tube protein Hcp1, which revealed a hexameric ring structure with an outer and inner diameter of 77 and 45Å, respectively. Structural comparison with homologs showed differences in the key loops connecting the β-strands in which the conserved residues are located, suggesting a role of these residues in the protein function. The T6SS is well-known to facilitate interbacterial competition, and the putative T6SS characterized herein might be responsible for the remarkable antagonism by C. haemolyticum WI5. Collectively, these findings shed light on the nature of bacterial antagonism and a putative key virulence determinant of C. haemolyticum, which might aid in further understanding its potential ecological role in natural habitats.
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Affiliation(s)
- Ye Htut Zwe
- Department of Food Science & Technology, 2 Science Drive 2, Faculty of Science, National University of Singapore, Singapore 117543
| | - Manisha Yadav
- Department of Biological Sciences, 14 Science Drive 4, Faculty of Science, National University of Singapore, Singapore 117543
| | - Michelle Mei Zhen Ten
- Department of Food Science & Technology, 2 Science Drive 2, Faculty of Science, National University of Singapore, Singapore 117543
| | - Mahalashmi Srinivasan
- Department of Biological Sciences, 14 Science Drive 4, Faculty of Science, National University of Singapore, Singapore 117543
| | - Chacko Jobichen
- Department of Biological Sciences, 14 Science Drive 4, Faculty of Science, National University of Singapore, Singapore 117543
| | - J Sivaraman
- Department of Biological Sciences, 14 Science Drive 4, Faculty of Science, National University of Singapore, Singapore 117543
| | - Dan Li
- Department of Food Science & Technology, 2 Science Drive 2, Faculty of Science, National University of Singapore, Singapore 117543.
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4
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Major tail proteins of bacteriophages of the order Caudovirales. J Biol Chem 2021; 298:101472. [PMID: 34890646 PMCID: PMC8718954 DOI: 10.1016/j.jbc.2021.101472] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 11/15/2021] [Accepted: 11/16/2021] [Indexed: 12/18/2022] Open
Abstract
Technological advances in cryo-EM in recent years have given rise to detailed atomic structures of bacteriophage tail tubes-a class of filamentous protein assemblies that could previously only be studied on the atomic scale in either their monomeric form or when packed within a crystal lattice. These hollow elongated protein structures, present in most bacteriophages of the order Caudovirales, connect the DNA-containing capsid with a receptor function at the distal end of the tail and consist of helical and polymerized major tail proteins. However, the resolution of cryo-EM data for these systems differs enormously between different tail tube types, partly inhibiting the building of high-fidelity models and barring a combination with further structural biology methods. Here, we review the structural biology efforts within this field and highlight the role of integrative structural biology approaches that have proved successful for some of these systems. Finally, we summarize the structural elements of major tail proteins and conceptualize how different amounts of tail tube flexibility confer heterogeneity within cryo-EM maps and, thus, limit high-resolution reconstructions.
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5
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Kalindamar S, Abdelhamed H, Kordon AO, Pinchuk LM, Karsi A. Hemolysin Co-regulated Family Proteins Hcp1 and Hcp2 Contribute to Edwardsiella ictaluri Pathogenesis. Front Vet Sci 2021; 8:681609. [PMID: 34150898 PMCID: PMC8207204 DOI: 10.3389/fvets.2021.681609] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2021] [Accepted: 05/07/2021] [Indexed: 01/22/2023] Open
Abstract
Edwardsiella ictaluri is a Gram-negative facultative intracellular pathogen causing enteric septicemia of catfish (ESC), a devastating disease resulting in significant economic losses in the U.S. catfish industry. Bacterial secretion systems are involved in many bacteria's virulence, and Type VI Secretion System (T6SS) is a critical apparatus utilized by several pathogenic Gram-negative bacteria. E. ictaluri strain 93-146 genome has a complete T6SS operon with 16 genes, but the roles of these genes are still not explored. In this research, we aimed to understand the roles of two hemolysin co-regulated family proteins, Hcp1 (EvpC) and Hcp2. To achieve this goal, single and double E. ictaluri mutants (EiΔevpC, EiΔhcp2, and EiΔevpCΔhcp2) were generated and characterized. Catfish peritoneal macrophages were able to kill EiΔhcp2 better than EiΔevpC, EiΔevpCΔhcp2, and E. ictaluri wild-type (EiWT). The attachment of EiΔhcp2 and EiΔevpCΔhcp2 to ovary cells significantly decreased compared to EiWT whereas the cell invasion rates of these mutants were the same as that of EiWT. Mutants exposed to normal catfish serum in vitro showed serum resistance. The fish challenges demonstrated that EiΔevpC and EiΔevpCΔhcp2 were attenuated completely and provided excellent protection against EiWT infection in catfish fingerlings. Interestingly, EiΔhcp2 caused higher mortality than that of EiWT in catfish fingerlings, and severe clinical signs were observed. Although fry were more susceptible to vaccination with EiΔevpC and EiΔevpCΔhcp2, their attenuation and protection were significantly higher compared to EiWT and sham groups, respectively. Taken together, our data indicated that evpC (hcp1) is involved in E. ictaluri virulence in catfish while hcp2 is involved in adhesion to epithelial cells and survival inside catfish macrophages.
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Affiliation(s)
- Safak Kalindamar
- Department of Molecular Biology and Genetics, Faculty of Arts and Sciences, Ordu University, Ordu, Turkey
| | - Hossam Abdelhamed
- Department of Comparative Biomedical Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, United States
| | - Adef O Kordon
- Department of Comparative Biomedical Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, United States
| | - Lesya M Pinchuk
- Department of Comparative Biomedical Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, United States
| | - Attila Karsi
- Department of Comparative Biomedical Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS, United States
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Goulet A, Spinelli S, Mahony J, Cambillau C. Conserved and Diverse Traits of Adhesion Devices from Siphoviridae Recognizing Proteinaceous or Saccharidic Receptors. Viruses 2020; 12:E512. [PMID: 32384698 PMCID: PMC7291167 DOI: 10.3390/v12050512] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 05/02/2020] [Accepted: 05/03/2020] [Indexed: 01/30/2023] Open
Abstract
Bacteriophages can play beneficial roles in phage therapy and destruction of food pathogens. Conversely, they play negative roles as they infect bacteria involved in fermentation, resulting in serious industrial losses. Siphoviridae phages possess a long non-contractile tail and use a mechanism of infection whose first step is host recognition and binding. They have evolved adhesion devices at their tails' distal end, tuned to recognize specific proteinaceous or saccharidic receptors on the host's surface that span a large spectrum of shapes. In this review, we aimed to identify common patterns beyond this apparent diversity. To this end, we analyzed siphophage tail tips or baseplates, evaluating their known structures, where available, and uncovering patterns with bioinformatics tools when they were not. It was thereby identified that a triad formed by three proteins in complex, i.e., the tape measure protein (TMP), the distal tail protein (Dit), and the tail-associated lysozyme (Tal), is conserved in all phages. This common scaffold may harbor various functional extensions internally while it also serves as a platform for plug-in ancillary or receptor-binding proteins (RBPs). Finally, a group of siphophage baseplates involved in saccharidic receptor recognition exhibits an activation mechanism reminiscent of that observed in Myoviridae.
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Affiliation(s)
- Adeline Goulet
- Architecture et Fonction des Macromolécules Biologiques, Aix-Marseille Université, Campus de Luminy, 13288 Marseille, France;
- Architecture et Fonction des Macromolécules Biologiques, Centre National de la Recherche Scientifique (CNRS), Campus de Luminy, 13288 Marseille, France
| | - Silvia Spinelli
- Architecture et Fonction des Macromolécules Biologiques, Aix-Marseille Université, Campus de Luminy, 13288 Marseille, France;
- Architecture et Fonction des Macromolécules Biologiques, Centre National de la Recherche Scientifique (CNRS), Campus de Luminy, 13288 Marseille, France
| | - Jennifer Mahony
- School of Microbiology, University College Cork, Cork T12 YN60, Ireland;
- APC Microbiome Ireland, University College Cork, Cork T12 YN60, Ireland
| | - Christian Cambillau
- Architecture et Fonction des Macromolécules Biologiques, Aix-Marseille Université, Campus de Luminy, 13288 Marseille, France;
- Architecture et Fonction des Macromolécules Biologiques, Centre National de la Recherche Scientifique (CNRS), Campus de Luminy, 13288 Marseille, France
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7
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Špakova A, Šimoliūnas E, Batiuškaitė R, Pajeda S, Meškys R, Petraitytė-Burneikienė R. Self-Assembly of Tail Tube Protein of Bacteriophage vB_EcoS_NBD2 into Extremely Long Polytubes in E. coli and S. cerevisiae. Viruses 2019; 11:E208. [PMID: 30832262 PMCID: PMC6466441 DOI: 10.3390/v11030208] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2019] [Revised: 02/22/2019] [Accepted: 02/26/2019] [Indexed: 01/01/2023] Open
Abstract
Nucleotides, peptides and proteins serve as a scaffold material for self-assembling nanostructures. In this study, the production of siphovirus vB_EcoS_NBD2 (NBD2) recombinant tail tube protein gp39 reached approximately 33% and 27% of the total cell protein level in Escherichia coli and Saccharomyces cerevisiae expression systems, respectively. A simple purification protocol allowed us to produce a recombinant gp39 protein with 85%⁻90% purity. The yield of gp39 was 2.9 ± 0.36 mg/g of wet E. coli cells and 0.85 ± 0.33 mg/g for S. cerevisiae cells. The recombinant gp39 self-assembled into well-ordered tubular structures (polytubes) in vivo in the absence of other phage proteins. The diameter of these structures was the same as the diameter of the tail of phage NBD2 (~12 nm). The length of these structures varied from 0.1 µm to >3.95 µm, which is 23-fold the normal NBD2 tail length. Stability analysis demonstrated that the polytubes could withstand various chemical and physical conditions. These polytubes show the potential to be used as a nanomaterial in various fields of science.
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Affiliation(s)
- Aliona Špakova
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Saulėtekio al. 7, LT-10257 Vilnius, Lithuania.
| | - Eugenijus Šimoliūnas
- Institute of Biochemistry, Life Sciences Center, Vilnius University, Saulėtekio al. 7, LT-10257 Vilnius, Lithuania.
| | - Raminta Batiuškaitė
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Saulėtekio al. 7, LT-10257 Vilnius, Lithuania.
| | - Simonas Pajeda
- Institute of Biochemistry, Life Sciences Center, Vilnius University, Saulėtekio al. 7, LT-10257 Vilnius, Lithuania.
| | - Rolandas Meškys
- Institute of Biochemistry, Life Sciences Center, Vilnius University, Saulėtekio al. 7, LT-10257 Vilnius, Lithuania.
| | - Rasa Petraitytė-Burneikienė
- Institute of Biotechnology, Life Sciences Center, Vilnius University, Saulėtekio al. 7, LT-10257 Vilnius, Lithuania.
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8
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An Y, Wang J, Li C, Leier A, Marquez-Lago T, Wilksch J, Zhang Y, Webb GI, Song J, Lithgow T. Comprehensive assessment and performance improvement of effector protein predictors for bacterial secretion systems III, IV and VI. Brief Bioinform 2018; 19:148-161. [PMID: 27777222 DOI: 10.1093/bib/bbw100] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2016] [Indexed: 11/15/2022] Open
Abstract
Bacterial effector proteins secreted by various protein secretion systems play crucial roles in host-pathogen interactions. In this context, computational tools capable of accurately predicting effector proteins of the various types of bacterial secretion systems are highly desirable. Existing computational approaches use different machine learning (ML) techniques and heterogeneous features derived from protein sequences and/or structural information. These predictors differ not only in terms of the used ML methods but also with respect to the used curated data sets, the features selection and their prediction performance. Here, we provide a comprehensive survey and benchmarking of currently available tools for the prediction of effector proteins of bacterial types III, IV and VI secretion systems (T3SS, T4SS and T6SS, respectively). We review core algorithms, feature selection techniques, tool availability and applicability and evaluate the prediction performance based on carefully curated independent test data sets. In an effort to improve predictive performance, we constructed three ensemble models based on ML algorithms by integrating the output of all individual predictors reviewed. Our benchmarks demonstrate that these ensemble models outperform all the reviewed tools for the prediction of effector proteins of T3SS and T4SS. The webserver of the proposed ensemble methods for T3SS and T4SS effector protein prediction is freely available at http://tbooster.erc.monash.edu/index.jsp. We anticipate that this survey will serve as a useful guide for interested users and that the new ensemble predictors will stimulate research into host-pathogen relationships and inspiration for the development of new bioinformatics tools for predicting effector proteins of T3SS, T4SS and T6SS.
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9
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Noreen Z, Jobichen C, Abbasi R, Seetharaman J, Sivaraman J, Bokhari H. Structural basis for the pathogenesis of Campylobacter jejuni Hcp1, a structural and effector protein of the Type VI Secretion System. FEBS J 2018; 285:4060-4070. [PMID: 30194714 DOI: 10.1111/febs.14650] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Revised: 08/17/2018] [Accepted: 09/03/2018] [Indexed: 12/22/2022]
Abstract
The Type VI Secretion System (T6SS) provides enhanced virulence to Campylobacter jejuni and has been associated with a high incidence of bloody diarrhea. The hemolysin-coregulated protein (Hcp)-the hallmark of the T6SS-can act as a structural and effector protein. Unlike other T6SS-harboring bacteria, which possess multiple Hcp proteins each performing different functions, C. jejuni possesses only one Hcp protein, and its structural and functional role has not been elucidated previously. Here, we report the structure and functional studies of Hcp from C. jejuni. We found similarities between the hexameric ring structure of Hcp-Cj and that of Hcp3 from Pseudomonas aeruginosa. Through functional studies, we showed two roles for Hcp-Cj that is, in cytotoxicity toward HepG2 cells and in biofilm formation in C. jejuni. In structure-based mutational analyses, we showed that an Arg-to-Ala mutation at position 30 within the extended loop results in a significant decrease in cytotoxicity, suggesting a role for this loop in binding to the host cell. However, this mutation does not affect its biofilm formation function. Collectively, this study supports the dual role of Hcp-Cj as a structural and effector protein in C. jejuni.
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Affiliation(s)
- Zobia Noreen
- Department of Biosciences, COMSATS University, Islamabad Campus, Islamabad, Pakistan
| | - Chacko Jobichen
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore
| | - Rashda Abbasi
- Institute of Biomedical and Genetic Engineering (IBGE), Islamabad, Pakistan
| | | | - J Sivaraman
- Department of Biological Sciences, Faculty of Science, National University of Singapore, Singapore
| | - Habib Bokhari
- Department of Biosciences, COMSATS University, Islamabad Campus, Islamabad, Pakistan
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10
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Paredes-Amaya CC, Valdés-García G, Juárez-González VR, Rudiño-Piñera E, Bustamante VH. The Hcp-like protein HilE inhibits homodimerization and DNA binding of the virulence-associated transcriptional regulator HilD in Salmonella. J Biol Chem 2018. [PMID: 29535187 DOI: 10.1074/jbc.ra117.001421] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
HilD is an AraC-like transcriptional regulator that plays a central role in Salmonella virulence. HilD controls the expression of the genes within the Salmonella pathogenicity island 1 (SPI-1) and of several genes located outside SPI-1, which are mainly required for Salmonella invasion of host cells. The expression, amount, and activity of HilD are tightly controlled by the activities of several factors. The HilE protein represses the expression of the SPI-1 genes through its interaction with HilD; however, the mechanism by which HilE affects HilD is unknown. In this study, we used genetic and biochemical assays revealing how HilE controls the transcriptional activity of HilD. We found that HilD needs to assemble in homodimers to induce expression of its target genes. Our results further indicated that HilE individually interacts with each the central and the C-terminal HilD regions, mediating dimerization and DNA binding, respectively. We also observed that these interactions consistently inhibit HilD dimerization and DNA binding. Interestingly, a computational analysis revealed that HilE shares sequence and structural similarities with Hcp proteins, which act as structural components of type 6 secretion systems in Gram-negative bacteria. In conclusion, our results uncover the molecular mechanism by which the Hcp-like protein HilE controls dimerization and DNA binding of the virulence-promoting transcriptional regulator HilD. Our findings may indicate that HilE's activity represents a functional adaptation during the evolution of Salmonella pathogenicity.
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Affiliation(s)
| | - Gilberto Valdés-García
- Molecular Medicine and Bioprocesses, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos 62210, México
| | - Víctor R Juárez-González
- Molecular Medicine and Bioprocesses, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos 62210, México
| | - Enrique Rudiño-Piñera
- Molecular Medicine and Bioprocesses, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos 62210, México
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11
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Salih O, He S, Planamente S, Stach L, MacDonald JT, Manoli E, Scheres SHW, Filloux A, Freemont PS. Atomic Structure of Type VI Contractile Sheath from Pseudomonas aeruginosa. Structure 2018; 26:329-336.e3. [PMID: 29307484 PMCID: PMC5807055 DOI: 10.1016/j.str.2017.12.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2017] [Revised: 09/28/2017] [Accepted: 12/06/2017] [Indexed: 01/01/2023]
Abstract
Pseudomonas aeruginosa has three type VI secretion systems (T6SSs), H1-, H2-, and H3-T6SS, each belonging to a distinct group. The two T6SS components, TssB/VipA and TssC/VipB, assemble to form tubules that conserve structural/functional homology with tail sheaths of contractile bacteriophages and pyocins. Here, we used cryoelectron microscopy to solve the structure of the H1-T6SS P. aeruginosa TssB1C1 sheath at 3.3 Å resolution. Our structure allowed us to resolve some features of the T6SS sheath that were not resolved in the Vibrio cholerae VipAB and Francisella tularensis IglAB structures. Comparison with sheath structures from other contractile machines, including T4 phage and R-type pyocins, provides a better understanding of how these systems have conserved similar functions/mechanisms despite evolution. We used the P. aeruginosa R2 pyocin as a structural template to build an atomic model of the TssB1C1 sheath in its extended conformation, allowing us to propose a coiled-spring-like mechanism for T6SS sheath contraction. We solved a T6SS sheath structure from Pseudomonas aeruginosa (group 3 T6SSi) Comparisons between T6SS groups suggest a conserved sheath contraction mechanism Extended-state model led to proposal of a spring-like sheath contraction mechanism
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Affiliation(s)
- Osman Salih
- Section of Structural Biology, Department of Medicine, Imperial College London, London SW7 2AZ, UK
| | - Shaoda He
- MRC Laboratory of Molecular Biology, Cambridge CB2 0QH, UK
| | - Sara Planamente
- MRC Centre for Molecular Bacteriology and Infection (CMBI), Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
| | - Lasse Stach
- Section of Structural Biology, Department of Medicine, Imperial College London, London SW7 2AZ, UK
| | - James T MacDonald
- Section of Structural Biology, Department of Medicine, Imperial College London, London SW7 2AZ, UK
| | - Eleni Manoli
- MRC Centre for Molecular Bacteriology and Infection (CMBI), Department of Life Sciences, Imperial College London, London SW7 2AZ, UK
| | | | - Alain Filloux
- MRC Centre for Molecular Bacteriology and Infection (CMBI), Department of Life Sciences, Imperial College London, London SW7 2AZ, UK.
| | - Paul S Freemont
- Section of Structural Biology, Department of Medicine, Imperial College London, London SW7 2AZ, UK.
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12
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Cryo-EM structure of the extended type VI secretion system sheath–tube complex. Nat Microbiol 2017; 2:1507-1512. [DOI: 10.1038/s41564-017-0020-7] [Citation(s) in RCA: 86] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Accepted: 08/02/2017] [Indexed: 11/08/2022]
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13
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Lin QP, Gao ZQ, Geng Z, Zhang H, Dong YH. Crystal structure of the putative cytoplasmic protein STM0279 (Hcp2) from Salmonella typhimurium. ACTA CRYSTALLOGRAPHICA SECTION F-STRUCTURAL BIOLOGY COMMUNICATIONS 2017; 73:463-468. [PMID: 28777089 DOI: 10.1107/s2053230x17010512] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2017] [Accepted: 07/15/2017] [Indexed: 11/10/2022]
Abstract
STM0279 is a putative cytoplasmic protein from Salmonella typhimurium and was recently renamed haemolysin co-regulated protein 2 (Hcp2), with the neighbouring STM0276 being Hcp1. Both of them are encoded by the type VI secretion system (T6SS) of the Salmonella pathogenicity island 6 (SPI-6) locus and have high sequence identity. The Hcp proteins may function as a vital component of the T6SS nanotube and as a transporter and chaperone of diverse effectors from the bacterial T6SS. In this study, the crystal structure and the oligomeric state in solution of Hcp2 from S. typhimurium (StHcp2) were investigated. The crystal structure refined to 3.0 Å resolution showed that the protein is composed of a β-barrel domain with extended loops and can form hexameric rings as observed in known Hcp homologues. Mutation of the extended loop was found to partly destabilize the hexameric conformation into monomers or cause the production of inclusion bodies, suggesting it has an important role in hexameric ring formation.
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Affiliation(s)
- Qing Peng Lin
- School of Life Sciences, University of Science and Technology of China, Hefei 230027, People's Republic of China
| | - Zeng Qiang Gao
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, People's Republic of China
| | - Zhi Geng
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, People's Republic of China
| | - Heng Zhang
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, People's Republic of China
| | - Yu Hui Dong
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, People's Republic of China
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Chang YW, Rettberg LA, Ortega DR, Jensen GJ. In vivo structures of an intact type VI secretion system revealed by electron cryotomography. EMBO Rep 2017; 18:1090-1099. [PMID: 28487352 DOI: 10.15252/embr.201744072] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Revised: 03/16/2017] [Accepted: 04/05/2017] [Indexed: 11/09/2022] Open
Abstract
The type VI secretion system (T6SS) is a versatile molecular weapon used by many bacteria against eukaryotic hosts or prokaryotic competitors. It consists of a cytoplasmic bacteriophage tail-like structure anchored in the bacterial cell envelope via a cytoplasmic baseplate and a periplasmic membrane complex. Rapid contraction of the sheath in the bacteriophage tail-like structure propels an inner tube/spike complex through the target cell envelope to deliver effectors. While structures of purified contracted sheath and purified membrane complex have been solved, because sheaths contract upon cell lysis and purification, no structure is available for the extended sheath. Structural information about the baseplate is also lacking. Here, we use electron cryotomography to directly visualize intact T6SS structures inside Myxococcus xanthus cells. Using sub-tomogram averaging, we resolve the structure of the extended sheath and membrane-associated components including the baseplate. Moreover, we identify novel extracellular bacteriophage tail fiber-like antennae. These results provide new structural insights into how the extended sheath prevents premature disassembly and how this sophisticated machine may recognize targets.
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Affiliation(s)
- Yi-Wei Chang
- California Institute of Technology, Pasadena, CA, USA
| | | | - Davi R Ortega
- California Institute of Technology, Pasadena, CA, USA
| | - Grant J Jensen
- California Institute of Technology, Pasadena, CA, USA .,Howard Hughes Medical Institute, Pasadena, CA, USA
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15
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Joshi A, Kostiuk B, Rogers A, Teschler J, Pukatzki S, Yildiz FH. Rules of Engagement: The Type VI Secretion System in Vibrio cholerae. Trends Microbiol 2017; 25:267-279. [PMID: 28027803 PMCID: PMC5365375 DOI: 10.1016/j.tim.2016.12.003] [Citation(s) in RCA: 81] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2016] [Revised: 12/04/2016] [Accepted: 12/07/2016] [Indexed: 11/16/2022]
Abstract
Microbial species often exist in complex communities where they must avoid predation and compete for favorable niches. The type VI secretion system (T6SS) is a contact-dependent bacterial weapon that allows for direct killing of competitors through the translocation of proteinaceous toxins. Vibrio cholerae is a Gram-negative pathogen that can use its T6SS during antagonistic interactions with neighboring prokaryotic and eukaryotic competitors. The T6SS not only promotes V. cholerae's survival during its aquatic and host life cycles, but also influences its evolution by facilitating horizontal gene transfer. This review details the recent insights regarding the structure and function of the T6SS as well as the diverse signals and regulatory pathways that control its activation in V. cholerae.
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Affiliation(s)
- Avatar Joshi
- Department of Microbiology and Environmental Toxicology, University of Santa Cruz, Santa Cruz, California, USA
| | - Benjamin Kostiuk
- Department of Medical Microbiology and Immunology, University of Alberta, Alberta, Canada
| | - Andrew Rogers
- Department of Microbiology and Environmental Toxicology, University of Santa Cruz, Santa Cruz, California, USA
| | - Jennifer Teschler
- Department of Microbiology and Environmental Toxicology, University of Santa Cruz, Santa Cruz, California, USA
| | - Stefan Pukatzki
- Department of Immunology and Microbiology, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Fitnat H Yildiz
- Department of Microbiology and Environmental Toxicology, University of Santa Cruz, Santa Cruz, California, USA.
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Basler M. Type VI secretion system: secretion by a contractile nanomachine. Philos Trans R Soc Lond B Biol Sci 2016; 370:rstb.2015.0021. [PMID: 26370934 PMCID: PMC4632598 DOI: 10.1098/rstb.2015.0021] [Citation(s) in RCA: 146] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The type VI secretion systems (T6SS) are present in about a quarter of all Gram-negative bacteria. Several key components of T6SS are evolutionarily related to components of contractile nanomachines such as phages and R-type pyocins. The T6SS assembly is initiated by formation of a membrane complex that binds a phage-like baseplate with a sharp spike, and this is followed by polymerization of a long rigid inner tube and an outer contractile sheath. Effectors are preloaded onto the spike or into the tube during the assembly by various mechanisms. Contraction of the sheath releases an unprecedented amount of energy, which is used to thrust the spike and tube with the associated effectors out of the effector cell and across membranes of both bacterial and eukaryotic target cells. Subunits of the contracted sheath are recycled by T6SS-specific unfoldase to allow for a new round of assembly. Live-cell imaging has shown that the assembly is highly dynamic and its subcellular localization is in certain bacteria regulated with a remarkable precision. Through the action of effectors, T6SS has mainly been shown to contribute to pathogenicity and competition between bacteria. This review summarizes the knowledge that has contributed to our current understanding of T6SS mode of action.
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Affiliation(s)
- Marek Basler
- Focal Area Infection Biology, Biozentrum, University of Basel, Basel, Switzerland
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Spínola-Amilibia M, Davó-Siguero I, Ruiz FM, Santillana E, Medrano FJ, Romero A. The structure of VgrG1 fromPseudomonas aeruginosa, the needle tip of the bacterial type VI secretion system. ACTA CRYSTALLOGRAPHICA SECTION D-STRUCTURAL BIOLOGY 2016; 72:22-33. [DOI: 10.1107/s2059798315021142] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Accepted: 11/06/2015] [Indexed: 11/10/2022]
Abstract
The type VI secretion system (T6SS) is a mechanism that is commonly used by pathogenic bacteria to infect host cells and for survival in competitive environments. This system assembles on a core baseplate and elongates like a phage puncturing device; it is thought to penetrate the target membrane and deliver effectors into the host or competing bacteria. Valine–glycine repeat protein G1 (VgrG1) forms the spike at the tip of the elongating tube formed by haemolysin co-regulated protein 1 (Hcp1); it is structurally similar to the T4 phage (gp27)3–(gp5)3puncturing complex. Here, the crystal structure of full-length VgrG1 fromPseudomonas aeruginosais reported at a resolution of 2.0 Å, which through a trimeric arrangement generates a needle-like shape composed of two main parts, the head and the spike, connectedviaa small neck region. The structure reveals several remarkable structural features pointing to the possible roles of the two main segments of VgrG1: the head as a scaffold cargo domain and the β-roll spike with implications in the cell-membrane puncturing process and as a carrier of cognate toxins.
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Aim, Load, Fire: The Type VI Secretion System, a Bacterial Nanoweapon. Trends Microbiol 2016; 24:51-62. [DOI: 10.1016/j.tim.2015.10.005] [Citation(s) in RCA: 267] [Impact Index Per Article: 33.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Revised: 09/30/2015] [Accepted: 10/09/2015] [Indexed: 12/31/2022]
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Angelucci F, Bellelli A, Ardini M, Ippoliti R, Saccoccia F, Morea V. One ring (or two) to hold them all – on the structure and function of protein nanotubes. FEBS J 2015; 282:2827-45. [PMID: 26059483 DOI: 10.1111/febs.13336] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Revised: 03/31/2015] [Accepted: 06/04/2015] [Indexed: 01/07/2023]
Abstract
Understanding the structural determinants relevant to the formation of supramolecular assemblies of homo-oligomeric proteins is a traditional and central scope of structural biology. The knowledge thus gained is crucial both to infer their physiological function and to exploit their architecture for bionanomaterials design. Protein nanotubes made by one-dimensional arrays of homo-oligomers can be generated by either a commutative mechanism, yielding an 'open' structure (e.g. actin), or a noncommutative mechanism, whereby the final structure is formed by hierarchical self-assembly of intermediate 'closed' structures. Examples of the latter process are poorly described and the rules by which they assemble have not been unequivocally defined. We have collected and investigated examples of homo-oligomeric circular arrangements that form one-dimensional filaments of stacked rings by the noncommutative mechanism in vivo and in vitro. Based on their quaternary structure, circular arrangements of protein subunits can be subdivided into two groups that we term Rings of Dimers (e.g. peroxiredoxin and stable protein 1) and Dimers of Rings (e.g. thermosome/rosettasome), depending on the sub-structures that can be identified within the assembly (and, in some cases, populated in solution under selected experimental conditions). Structural analysis allowed us to identify the determinants by which ring-like molecular chaperones form filamentous-like assemblies and to formulate a novel hypothesis by which nanotube assembly, molecular chaperone activity and macromolecular crowding may be interconnected.
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Affiliation(s)
- Francesco Angelucci
- Department of Health, Life and Environmental Sciences, University of L'Aquila, Italy
| | - Andrea Bellelli
- Department of Biochemical Sciences 'A. Rossi Fanelli', Sapienza University of Rome and Istituto Pasteur-Fondazione Cenci Bolognetti, Rome, Italy
| | - Matteo Ardini
- Department of Health, Life and Environmental Sciences, University of L'Aquila, Italy
| | - Rodolfo Ippoliti
- Department of Health, Life and Environmental Sciences, University of L'Aquila, Italy
| | - Fulvio Saccoccia
- Department of Biochemical Sciences 'A. Rossi Fanelli', Sapienza University of Rome and Istituto Pasteur-Fondazione Cenci Bolognetti, Rome, Italy
| | - Veronica Morea
- CNR - National Research Council of Italy, Institute of Molecular Biology and Pathology, Rome, Italy
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Crystal Structure of Hcp from Acinetobacter baumannii: A Component of the Type VI Secretion System. PLoS One 2015; 10:e0129691. [PMID: 26079269 PMCID: PMC4469607 DOI: 10.1371/journal.pone.0129691] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Accepted: 05/12/2015] [Indexed: 11/19/2022] Open
Abstract
The type VI secretion system (T6SS) is a bacterial macromolecular machine widely distributed in Gram-negative bacteria, which transports effector proteins into eukaryotic host cells or other bacteria. Membrane complexes and a central tubular structure, which resembles the tail of contractile bacteriophages, compose the T6SS. One of the proteins forming this tube is the hemolysin co-regulated protein (Hcp), which acts as virulence factor, as transporter of effectors and as a chaperone. In this study, we present the structure of Hcp from Acinetobacter baumannii, together with functional and oligomerization studies. The structure of this protein exhibits a tight β barrel formed by two β sheets and flanked at one side by a short α-helix. Six Hcp molecules associate to form a donut-shaped hexamer, as observed in both the crystal structure and solution. These results emphasize the importance of this oligomerization state in this family of proteins, despite the low similarity of sequence among them. The structure presented in this study is the first one for a protein forming part of a functional T6SS from A. baumannii. These results will help us to understand the mechanism and function of this secretion system in this opportunistic nosocomial pathogen.
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Shyntum DY, Theron J, Venter SN, Moleleki LN, Toth IK, Coutinho TA. Pantoea ananatis Utilizes a Type VI Secretion System for Pathogenesis and Bacterial Competition. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2015; 28:420-431. [PMID: 25411959 DOI: 10.1094/mpmi-07-14-0219-r] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Type VI secretion systems (T6SSs) are a class of macromolecular machines that are recognized as an important virulence mechanism in several gram-negative bacteria. The genome of Pantoea ananatis LMG 2665(T), a pathogen of pineapple fruit and onion plants, carries two gene clusters whose predicted products have homology with T6SS-associated gene products from other bacteria. Nothing is known regarding the role of these T6SS-1 and T6SS-3 gene clusters in the biology of P. ananatis. Here, we present evidence that T6SS-1 plays an important role in the pathogenicity of P. ananatis LMG 2665(T) in onion plants, while a strain lacking T6SS-3 remains as pathogenic as the wild-type strain. We also investigated the role of the T6SS-1 system in bacterial competition, the results of which indicated that several bacteria compete less efficiently against wild-type LMG 2665(T) than a strain lacking T6SS-1. Additionally, we demonstrated that these phenotypes of strain LMG 2665(T) were reliant on the core T6SS products TssA and TssD (Hcp), thus indicating that the T6SS-1 gene cluster encodes a functioning T6SS. Collectively, our data provide the first evidence demonstrating that the T6SS-1 system is a virulence determinant of P. ananatis LMG 2665(T) and plays a role in bacterial competition.
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Affiliation(s)
- Divine Y Shyntum
- 1 Department of Microbiology and Plant Pathology, Faculty of Natural and Agricultural Sciences, and
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23
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Atomic structures of a bactericidal contractile nanotube in its pre- and postcontraction states. Nat Struct Mol Biol 2015; 22:377-82. [PMID: 25822993 DOI: 10.1038/nsmb.2995] [Citation(s) in RCA: 121] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Accepted: 02/25/2015] [Indexed: 01/01/2023]
Abstract
R-type pyocins are representatives of contractile ejection systems, a class of biological nanomachines that includes, among others, the bacterial type VI secretion system (T6SS) and contractile bacteriophage tails. We report atomic models of the Pseudomonas aeruginosa precontraction pyocin sheath and tube, and the postcontraction sheath, obtained by cryo-EM at 3.5-Å and 3.9-Å resolutions, respectively. The central channel of the tube is negatively charged, in contrast to the neutral and positive counterparts in T6SSs and phage tails. The sheath is interwoven by long N- and C-terminal extension arms emanating from each subunit, which create an extensive two-dimensional mesh that has the same connectivity in the extended and contracted state of the sheath. We propose that the contraction process draws energy from electrostatic and shape complementarities to insert the inner tube through bacterial cell membranes to eventually kill the bacteria.
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Li J, Mo Z, Li G, Xiao P, Huang J. Generation and evaluation of virulence attenuated mutants of Edwardsiella tarda as vaccine candidates to combat edwardsiellosis in flounder (Paralichthys olivaceus). FISH & SHELLFISH IMMUNOLOGY 2015; 43:175-180. [PMID: 25541077 DOI: 10.1016/j.fsi.2014.12.018] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2014] [Revised: 12/03/2014] [Accepted: 12/15/2014] [Indexed: 06/04/2023]
Abstract
Edwardsiella tarda is an intracellular pathogen that causes edwardsiellosis in fish. The development of a live attenuated vaccine may be an effective approach for preventing this disease in fish. In this study, we introduced deletions of esrB, esaC, evpH, rpoS, and purA into the E. tarda LSE40ΔaroA strain, thereby generating five double-gene mutants (ΔaroAΔesrB, ΔaroAΔesaC, ΔaroAΔrpoS, ΔaroAΔevpH, and ΔaroAΔpurA) and two triple-gene mutants (ΔaroAΔesrBΔevpH and ΔaroAΔesaCΔevpH). When blue gourami (Trichogaster trichopterus) was used as a fish model for the primary screening and evaluation of the vaccine candidates, all mutants were attenuated significantly by more than 2 to 3 logs in terms of the 50% lethal dose (LD(50)). Five double-gene mutants yielded relative percentage survival (RPS) rates of 26.1-82.6% after challenge with wild-type E. tarda. The ΔaroAΔesrB mutant that conferred the highest RPS (82.6%) in blue gourami was also evaluated in flounder (Paralichthys olivaceus). After vaccination via intramuscular (i.m.) injection or immersion, this mutant could persist in the flounder for 14-35 days and it induced higher serum antibody titers than the control fish (P < 0.01). Flounder vaccinated via i.m. injection at doses of 10(3)-10(7) CFU/fish had RPS rates of 14.3-66.7% after i.m. challenge with 10(4) CFU/fish using wild-type E. tarda. Flounder vaccinated via immersion at a dose of 10(7) CFU/ml exhibited 100% RPS against immersion challenge with 10(7) CFU/ml using wild-type E. tarda. These results indicate that the ΔaroAΔesrB mutant could be used as an effective live vaccine to combat edwardsiellosis in flounder.
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Affiliation(s)
- Jie Li
- Key Laboratory of Sustainable Development of Marine Fisheries, The Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, China; National Laboratory for Marine Science and Technology, Qingdao, China
| | - Zhaolan Mo
- Key Laboratory of Sustainable Development of Marine Fisheries, The Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, China; National Laboratory for Marine Science and Technology, Qingdao, China.
| | - Guiyang Li
- Key Laboratory of Sustainable Development of Marine Fisheries, The Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, China; National Laboratory for Marine Science and Technology, Qingdao, China
| | - Peng Xiao
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China
| | - Jie Huang
- Key Laboratory of Sustainable Development of Marine Fisheries, The Ministry of Agriculture, Yellow Sea Fisheries Research Institute, Chinese Academy of Fishery Sciences, Qingdao, China; National Laboratory for Marine Science and Technology, Qingdao, China
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Lee SJ, Lee KY, Lee KY, Kim DG, Kim SJ, Lee BJ. Crystal structure of YwpF from Staphylococcus aureus reveals its architecture comprised of a β-barrel core domain resembling type VI secretion system proteins and a two-helix pair. Proteins 2015; 83:781-8. [PMID: 25663006 DOI: 10.1002/prot.24774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2014] [Revised: 01/11/2015] [Accepted: 01/21/2015] [Indexed: 11/10/2022]
Abstract
The ywpF gene (SAV2097) of the Staphylococcus aureus strain Mu50 encodes the YwpF protein, which may play a role in antibiotic resistance. Here, we report the first crystal structure of the YwpF superfamily from S. aureus at 2.5-Å resolution. The YwpF structure consists of two regions: an N-terminal core β-barrel domain that shows structural similarity to type VI secretion system (T6SS) proteins (e.g., Hcp1, Hcp3, and EvpC) and a C-terminal two-helix pair. Although the monomer structure of S. aureus YwpF resembles those of T6SS proteins, the dimer/tetramer model of S. aureus YwpF is distinct from the functionally important hexameric ring of T6SS proteins. We therefore suggest that the S. aureus YwpF may have a different function compared to T6SS proteins.
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Affiliation(s)
- Sang Jae Lee
- The Research Institute of Pharmaceutical Sciences, College of Pharmacy, Seoul National University, Gwanak-Gu, Seoul, 151-742, Korea
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Lim YT, Jobichen C, Wong J, Limmathurotsakul D, Li S, Chen Y, Raida M, Srinivasan N, MacAry PA, Sivaraman J, Gan YH. Extended loop region of Hcp1 is critical for the assembly and function of type VI secretion system in Burkholderia pseudomallei. Sci Rep 2015; 5:8235. [PMID: 25648885 PMCID: PMC4650826 DOI: 10.1038/srep08235] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Accepted: 01/13/2015] [Indexed: 11/09/2022] Open
Abstract
The Type VI Secretion System cluster 1 (T6SS1) is essential for the pathogenesis of Burkholderia pseudomallei, the causative agent of melioidosis, a disease endemic in the tropics. Inside host cells, B. pseudomallei escapes into the cytosol and through T6SS1, induces multinucleated giant cell (MNGC) formation that is thought to be important for bacterial cell to cell spread. The hemolysin-coregulated protein (Hcp) is both a T6SS substrate, as well as postulated to form part of the T6SS secretion tube. Our structural study reveals that Hcp1 forms hexameric rings similar to the other Hcp homologs but has an extended loop (Asp40-Arg56) that deviates significantly in position compared to other Hcp structures and may act as a key contact point between adjacent hexameric rings. When two residues within the loop were mutated, the mutant proteins were unable to stack as dodecamers, suggesting defective tube assembly. Moreover, infection with a bacterial mutant containing in situ substitution of these hcp1 residues abolishes Hcp1 secretion inside infected cells and MNGC formation. We further show that Hcp has the ability to preferentially bind to the surface of antigen-presenting cells, which may contribute to its immunogenicity in inducing high titers of antibodies seen in melioidosis patients.
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Affiliation(s)
- Yan Ting Lim
- 1] Department of Microbiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore [2] NUS Graduate School of Integrative Sciences and Engineering, National University of Singapore, Singapore [3] Life Sciences Institute, Immunology Program, National University of Singapore, Singapore
| | - Chacko Jobichen
- Department of Biological Sciences, National University of Singapore, Singapore
| | - Jocelyn Wong
- 1] Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore [2] NUS Graduate School of Integrative Sciences and Engineering, National University of Singapore, Singapore
| | - Direk Limmathurotsakul
- Department of Tropical Hygiene and Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Shaowei Li
- National Institute of Diagnostics and Vaccine Development in Infectious Diseases, School of Life Sciences, Xiamen University, Xiamen, China
| | - Yahua Chen
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Manfred Raida
- Life Sciences Institute, Singapore Lipidomics Incubator, National University of Singapore, Singapore
| | - Nalini Srinivasan
- Department of Microbiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Paul Anthony MacAry
- 1] Department of Microbiology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore [2] Life Sciences Institute, Immunology Program, National University of Singapore, Singapore
| | - J Sivaraman
- Department of Biological Sciences, National University of Singapore, Singapore
| | - Yunn-Hwen Gan
- Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
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Langlois C, Ramboarina S, Cukkemane A, Auzat I, Chagot B, Gilquin B, Ignatiou A, Petitpas I, Kasotakis E, Paternostre M, White HE, Orlova EV, Baldus M, Tavares P, Zinn-Justin S. Bacteriophage SPP1 tail tube protein self-assembles into β-structure-rich tubes. J Biol Chem 2014; 290:3836-49. [PMID: 25525268 DOI: 10.1074/jbc.m114.613166] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The majority of known bacteriophages have long tails that serve for bacterial target recognition and viral DNA delivery into the host. These structures form a tube from the viral capsid to the bacterial cell. The tube is formed primarily by a helical array of tail tube protein (TTP) subunits. In phages with a contractile tail, the TTP tube is surrounded by a sheath structure. Here, we report the first evidence that a phage TTP, gp17.1 of siphophage SPP1, self-assembles into long tubes in the absence of other viral proteins. gp17.1 does not exhibit a stable globular structure when monomeric in solution, even if it was confidently predicted to adopt the β-sandwich fold of phage λ TTP. However, Fourier transform infrared and nuclear magnetic resonance spectroscopy analyses showed that its β-sheet content increases significantly during tube assembly, suggesting that gp17.1 acquires a stable β-sandwich fold only after self-assembly. EM analyses revealed that the tube is formed by hexameric rings stacked helicoidally with the same organization and helical parameters found for the tail of SPP1 virions. These parameters were used to build a pseudo-atomic model of the TTP tube. The large loop spanning residues 40-56 is located on the inner surface of the tube, at the interface between adjacent monomers and hexamers. In line with our structural predictions, deletion of this loop hinders gp17.1 tube assembly in vitro and interferes with SPP1 tail assembly during phage particle morphogenesis in bacteria.
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Affiliation(s)
- Chantal Langlois
- From the Laboratoire de Biologie Structurale et Radiobiologie, UMR CNRS 8221 and CEA IBITECS, Commissariat à l'Energie Atomique, Saclay 91191 Gif-sur-Yvette Cedex, France
| | - Stéphanie Ramboarina
- From the Laboratoire de Biologie Structurale et Radiobiologie, UMR CNRS 8221 and CEA IBITECS, Commissariat à l'Energie Atomique, Saclay 91191 Gif-sur-Yvette Cedex, France
| | - Abhishek Cukkemane
- the NMR Spectroscopy Group, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands, the Microbiology Department, Tuljaram Chaturchand College, Baramati-413102, India
| | - Isabelle Auzat
- the Unité de Virologie Moléculaire et Structurale, CNRS UPR3296, Centre de Recherche de Gif, Bâtiment 14B, CNRS, 91198 Gif-sur-Yvette, France, and
| | - Benjamin Chagot
- From the Laboratoire de Biologie Structurale et Radiobiologie, UMR CNRS 8221 and CEA IBITECS, Commissariat à l'Energie Atomique, Saclay 91191 Gif-sur-Yvette Cedex, France
| | - Bernard Gilquin
- From the Laboratoire de Biologie Structurale et Radiobiologie, UMR CNRS 8221 and CEA IBITECS, Commissariat à l'Energie Atomique, Saclay 91191 Gif-sur-Yvette Cedex, France
| | - Athanasios Ignatiou
- the Institute of Structural and Molecular Biology, Birkbeck College, London WC1E 7HX, United Kingdom
| | - Isabelle Petitpas
- the Unité de Virologie Moléculaire et Structurale, CNRS UPR3296, Centre de Recherche de Gif, Bâtiment 14B, CNRS, 91198 Gif-sur-Yvette, France, and
| | - Emmanouil Kasotakis
- From the Laboratoire de Biologie Structurale et Radiobiologie, UMR CNRS 8221 and CEA IBITECS, Commissariat à l'Energie Atomique, Saclay 91191 Gif-sur-Yvette Cedex, France
| | - Maïté Paternostre
- From the Laboratoire de Biologie Structurale et Radiobiologie, UMR CNRS 8221 and CEA IBITECS, Commissariat à l'Energie Atomique, Saclay 91191 Gif-sur-Yvette Cedex, France
| | - Helen E White
- the Institute of Structural and Molecular Biology, Birkbeck College, London WC1E 7HX, United Kingdom
| | - Elena V Orlova
- the Institute of Structural and Molecular Biology, Birkbeck College, London WC1E 7HX, United Kingdom
| | - Marc Baldus
- the NMR Spectroscopy Group, Bijvoet Center for Biomolecular Research, Department of Chemistry, Faculty of Science, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands
| | - Paulo Tavares
- the Unité de Virologie Moléculaire et Structurale, CNRS UPR3296, Centre de Recherche de Gif, Bâtiment 14B, CNRS, 91198 Gif-sur-Yvette, France, and
| | - Sophie Zinn-Justin
- From the Laboratoire de Biologie Structurale et Radiobiologie, UMR CNRS 8221 and CEA IBITECS, Commissariat à l'Energie Atomique, Saclay 91191 Gif-sur-Yvette Cedex, France,
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A disordered region in the EvpP protein from the type VI secretion system of Edwardsiella tarda is essential for EvpC binding. PLoS One 2014; 9:e110810. [PMID: 25401506 PMCID: PMC4234509 DOI: 10.1371/journal.pone.0110810] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Accepted: 09/21/2014] [Indexed: 11/19/2022] Open
Abstract
The type VI secretion system (T6SS) of pathogenic bacteria plays important roles in both virulence and inter-bacterial competitions. The effectors of T6SS are presumed to be transported either by attaching to the tip protein or by interacting with HcpI (haemolysin corregulated protein 1). In Edwardsiella tarda PPD130/91, the T6SS secreted protein EvpP (E. tardavirulent protein P) is found to be essential for virulence and directly interacts with EvpC (Hcp-like), suggesting that it could be a potential effector. Using limited protease digestion, nuclear magnetic resonance heteronuclear Nuclear Overhauser Effects, and hydrogen-deuterium exchange mass spectrometry, we confirmed that the dimeric EvpP (40 kDa) contains a substantial proportion (40%) of disordered regions but still maintains an ordered and folded core domain. We show that an N-terminal, 10-kDa, protease-resistant fragment in EvpP connects to a shorter, 4-kDa protease-resistant fragment through a highly flexible region, which is followed by another disordered region at the C-terminus. Within this C-terminal disordered region, residues Pro143 to Ile168 are essential for its interaction with EvpC. Unlike the highly unfolded T3SS effector, which has a lower molecular weight and is maintained in an unfolded conformation with a dedicated chaperone, the T6SS effector seems to be relatively larger, folded but partially disordered and uses HcpI as a chaperone.
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Zoued A, Brunet YR, Durand E, Aschtgen MS, Logger L, Douzi B, Journet L, Cambillau C, Cascales E. Architecture and assembly of the Type VI secretion system. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:1664-73. [PMID: 24681160 DOI: 10.1016/j.bbamcr.2014.03.018] [Citation(s) in RCA: 172] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Revised: 03/17/2014] [Accepted: 03/18/2014] [Indexed: 12/31/2022]
Abstract
The Type VI secretion system (T6SS) delivers protein effectors to diverse cell types including prokaryotic and eukaryotic cells, therefore it participates in inter-bacterial competition and pathogenesis. The T6SS is constituted of an envelope-spanning complex anchoring a cytoplasmic tubular edifice. This tubular structure is evolutionarily, functionally and structurally related to the tail of contractile phages. It is composed of an inner tube tipped by a spike complex, and engulfed within a sheath-like structure. This structure assembles onto a platform called "baseplate" that is connected to the membrane sub-complex. The T6SS functions as a nano-crossbow: upon contraction of the sheath, the inner tube is propelled towards the target cell, allowing effector delivery. This review focuses on the architecture and biogenesis of this fascinating secretion machine, highlighting recent advances regarding the assembly of the membrane or tail complexes. This article is part of a Special Issue entitled: Protein trafficking and secretion in bacteria. Guest Editors: Anastassios Economou and Ross Dalbey.
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Affiliation(s)
- Abdelrahim Zoued
- Laboratoire d'Ingeniérie des Systèmes Macromoléculaires, CNRS, Aix-Marseille Université, UMR 7255, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France
| | - Yannick R Brunet
- Laboratoire d'Ingeniérie des Systèmes Macromoléculaires, CNRS, Aix-Marseille Université, UMR 7255, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France
| | - Eric Durand
- Architecture et Fonction des Macromolécules Biologiques, CNRS, Aix-Marseille Université, UMR 7257, Campus de Luminy, Case 932, 13288 Marseille Cedex 09, France
| | - Marie-Stéphanie Aschtgen
- Laboratoire d'Ingeniérie des Systèmes Macromoléculaires, CNRS, Aix-Marseille Université, UMR 7255, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France
| | - Laureen Logger
- Laboratoire d'Ingeniérie des Systèmes Macromoléculaires, CNRS, Aix-Marseille Université, UMR 7255, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France
| | - Badreddine Douzi
- Architecture et Fonction des Macromolécules Biologiques, CNRS, Aix-Marseille Université, UMR 7257, Campus de Luminy, Case 932, 13288 Marseille Cedex 09, France
| | - Laure Journet
- Laboratoire d'Ingeniérie des Systèmes Macromoléculaires, CNRS, Aix-Marseille Université, UMR 7255, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France
| | - Christian Cambillau
- Architecture et Fonction des Macromolécules Biologiques, CNRS, Aix-Marseille Université, UMR 7257, Campus de Luminy, Case 932, 13288 Marseille Cedex 09, France
| | - Eric Cascales
- Laboratoire d'Ingeniérie des Systèmes Macromoléculaires, CNRS, Aix-Marseille Université, UMR 7255, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France.
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Douzi B, Spinelli S, Blangy S, Roussel A, Durand E, Brunet YR, Cascales E, Cambillau C. Crystal structure and self-interaction of the type VI secretion tail-tube protein from enteroaggregative Escherichia coli. PLoS One 2014; 9:e86918. [PMID: 24551044 PMCID: PMC3925092 DOI: 10.1371/journal.pone.0086918] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2013] [Accepted: 12/15/2013] [Indexed: 11/29/2022] Open
Abstract
The type VI secretion system (T6SS) is a widespread machine used by bacteria to control their environment and kill or disable bacterial species or eukaryotes through toxin injection. The T6SS comprises a central tube formed of stacked hexamers of hemolysin co-regulated proteins (Hcp) and terminated by a trimeric valine-glycine repeat protein G (VgrG) component, the cell puncturing device. A contractile tail sheath, formed by the TssB and TssC proteins, surrounds this tube. This syringe-like machine has been compared to an inverted phage, as both Hcp and VgrG share structural homology with tail components of Caudovirales. Here we solved the crystal structure of a tryptophan-substituted double mutant of Hcp1 from enteroaggregative Escherichia coli and compared it to the structures of other Hcps. Interestingly, we observed that the purified Hcp native protein is unable to form tubes in vitro. To better understand the rationale for observation, we measured the affinity of Hcp1 hexamers with themselves by surface plasmon resonance. The intra-hexamer interaction is weak, with a KD value of 7.2 µM. However, by engineering double cysteine mutants at defined positions, tubes of Hcp1 gathering up to 15 stacked hexamers formed in oxidative conditions. These results, together with those available in the literature regarding TssB and TssC, suggest that assembly of the T6SS tube differs significantly from that of Sipho- or Myoviridae.
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Affiliation(s)
- Badreddine Douzi
- Aix-Marseille Université, Architecture et Fonction des Macromolécules Biologiques, UMR 7257, Campus de Luminy, Case 932, Marseille, France
- Centre National de la Recherche Scientifique, Architecture et Fonction des Macromolécules Biologiques, UMR 7257, Campus de Luminy, Case 932, Marseille, France
| | - Silvia Spinelli
- Aix-Marseille Université, Architecture et Fonction des Macromolécules Biologiques, UMR 7257, Campus de Luminy, Case 932, Marseille, France
- Centre National de la Recherche Scientifique, Architecture et Fonction des Macromolécules Biologiques, UMR 7257, Campus de Luminy, Case 932, Marseille, France
| | - Stéphanie Blangy
- Aix-Marseille Université, Architecture et Fonction des Macromolécules Biologiques, UMR 7257, Campus de Luminy, Case 932, Marseille, France
- Centre National de la Recherche Scientifique, Architecture et Fonction des Macromolécules Biologiques, UMR 7257, Campus de Luminy, Case 932, Marseille, France
| | - Alain Roussel
- Aix-Marseille Université, Architecture et Fonction des Macromolécules Biologiques, UMR 7257, Campus de Luminy, Case 932, Marseille, France
- Centre National de la Recherche Scientifique, Architecture et Fonction des Macromolécules Biologiques, UMR 7257, Campus de Luminy, Case 932, Marseille, France
| | - Eric Durand
- Aix-Marseille Université, Architecture et Fonction des Macromolécules Biologiques, UMR 7257, Campus de Luminy, Case 932, Marseille, France
- Centre National de la Recherche Scientifique, Architecture et Fonction des Macromolécules Biologiques, UMR 7257, Campus de Luminy, Case 932, Marseille, France
| | - Yannick R. Brunet
- Laboratoire d’Ingénierie des Systèmes Macromoléculaires, Institut de Microbiologie de la Méditerranée, Centre National de la Recherche Scientifique UMR7255, Aix-Marseille Université, Marseille, France
| | - Eric Cascales
- Laboratoire d’Ingénierie des Systèmes Macromoléculaires, Institut de Microbiologie de la Méditerranée, Centre National de la Recherche Scientifique UMR7255, Aix-Marseille Université, Marseille, France
| | - Christian Cambillau
- Aix-Marseille Université, Architecture et Fonction des Macromolécules Biologiques, UMR 7257, Campus de Luminy, Case 932, Marseille, France
- Centre National de la Recherche Scientifique, Architecture et Fonction des Macromolécules Biologiques, UMR 7257, Campus de Luminy, Case 932, Marseille, France
- * E-mail:
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Brunet YR, Hénin J, Celia H, Cascales E. Type VI secretion and bacteriophage tail tubes share a common assembly pathway. EMBO Rep 2014; 15:315-21. [PMID: 24488256 DOI: 10.1002/embr.201337936] [Citation(s) in RCA: 106] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
The Type VI secretion system (T6SS) is a widespread macromolecular structure that delivers protein effectors to both eukaryotic and prokaryotic recipient cells. The current model describes the T6SS as an inverted phage tail composed of a sheath-like structure wrapped around a tube assembled by stacked Hcp hexamers. Although recent progress has been made to understand T6SS sheath assembly and dynamics, there is no evidence that Hcp forms tubes in vivo. Here we show that Hcp interacts with TssB, a component of the T6SS sheath. Using a cysteine substitution approach, we demonstrate that Hcp hexamers assemble tubes in an ordered manner with a head-to-tail stacking that are used as a scaffold for polymerization of the TssB/C sheath-like structure. Finally, we show that VgrG but not TssB/C controls the proper assembly of the Hcp tubular structure. These results highlight the conservation in the assembly mechanisms between the T6SS and the bacteriophage tail tube/sheath.
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Affiliation(s)
- Yannick R Brunet
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, Institut de Microbiologie de la Méditerranée CNRS - UMR 7255 Aix-Marseille University, Marseille, France
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Spinelli S, Veesler D, Bebeacua C, Cambillau C. Structures and host-adhesion mechanisms of lactococcal siphophages. Front Microbiol 2014; 5:3. [PMID: 24474948 PMCID: PMC3893620 DOI: 10.3389/fmicb.2014.00003] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2013] [Accepted: 01/04/2014] [Indexed: 12/29/2022] Open
Abstract
The Siphoviridae family of bacteriophages is the largest viral family on earth and comprises members infecting both bacteria and archaea. Lactococcal siphophages infect the Gram-positive bacterium Lactococcus lactis, which is widely used for industrial milk fermentation processes (e.g., cheese production). As a result, lactococcal phages have become one of the most thoroughly characterized class of phages from a genomic standpoint. They exhibit amazing and intriguing characteristics. First, each phage has a strict specificity toward a unique or a handful of L. lactis host strains. Second, most lactococcal phages possess a large organelle at their tail tip (termed the baseplate), bearing the receptor binding proteins (RBPs) and mediating host adsorption. The recent accumulation of structural and functional data revealed the modular structure of their building blocks, their different mechanisms of activation and the fine specificity of their RBPs. These results also illustrate similarities and differences between lactococcal Siphoviridae and Gram-negative infecting Myoviridae.
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Affiliation(s)
- Silvia Spinelli
- Architecture et Fonction des Macromolécules Biologiques, UMR 7257, Aix-Marseille Université Marseille, France ; Architecture et Fonction des Macromolécules Biologiques, UMR 7257, Centre National de la Recherche Scientifique Marseille, France
| | - David Veesler
- Architecture et Fonction des Macromolécules Biologiques, UMR 7257, Aix-Marseille Université Marseille, France ; Architecture et Fonction des Macromolécules Biologiques, UMR 7257, Centre National de la Recherche Scientifique Marseille, France
| | - Cecilia Bebeacua
- Architecture et Fonction des Macromolécules Biologiques, UMR 7257, Aix-Marseille Université Marseille, France ; Architecture et Fonction des Macromolécules Biologiques, UMR 7257, Centre National de la Recherche Scientifique Marseille, France
| | - Christian Cambillau
- Architecture et Fonction des Macromolécules Biologiques, UMR 7257, Aix-Marseille Université Marseille, France ; Architecture et Fonction des Macromolécules Biologiques, UMR 7257, Centre National de la Recherche Scientifique Marseille, France
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Zoued A, Durand E, Bebeacua C, Brunet YR, Douzi B, Cambillau C, Cascales E, Journet L. TssK is a trimeric cytoplasmic protein interacting with components of both phage-like and membrane anchoring complexes of the type VI secretion system. J Biol Chem 2013; 288:27031-27041. [PMID: 23921384 PMCID: PMC3779704 DOI: 10.1074/jbc.m113.499772] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Revised: 08/05/2013] [Indexed: 11/06/2022] Open
Abstract
The Type VI secretion system (T6SS) is a macromolecular machine that mediates bacteria-host or bacteria-bacteria interactions. The T6SS core apparatus assembles from 13 proteins that form two sub-assemblies: a phage-like complex and a trans-envelope complex. The Hcp, VgrG, TssE, and TssB/C subunits are structurally and functionally related to components of the tail of contractile bacteriophages. This phage-like structure is thought to be anchored to the membrane by a trans-envelope complex composed of the TssJ, TssL, and TssM proteins. However, how the two sub-complexes are connected remains unknown. Here we identify TssK, a protein that establishes contacts with the two T6SS sub-complexes through direct interactions with TssL, Hcp, and TssC. TssK is a cytoplasmic protein assembling trimers that display a three-armed shape, as revealed by TEM and SAXS analyses. Fluorescence microscopy experiments further demonstrate the requirement of TssK for sheath assembly. Our results suggest a central role for TssK by linking both complexes during T6SS assembly.
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Affiliation(s)
- Abdelrahim Zoued
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, Institut de Microbiologie de la Méditerranée, CNRS, UMR 7255, Aix-Marseille Université, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France
| | - Eric Durand
- Architecture et Fonction des Macromolécules Biologiques, Campus de Luminy, Case 932, Aix-Marseille Université, CNRS UMR 6098, 13288 Marseille Cedex 09, France
| | - Cecilia Bebeacua
- Architecture et Fonction des Macromolécules Biologiques, Campus de Luminy, Case 932, Aix-Marseille Université, CNRS UMR 6098, 13288 Marseille Cedex 09, France
| | - Yannick R Brunet
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, Institut de Microbiologie de la Méditerranée, CNRS, UMR 7255, Aix-Marseille Université, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France
| | - Badreddine Douzi
- Architecture et Fonction des Macromolécules Biologiques, Campus de Luminy, Case 932, Aix-Marseille Université, CNRS UMR 6098, 13288 Marseille Cedex 09, France
| | - Christian Cambillau
- Architecture et Fonction des Macromolécules Biologiques, Campus de Luminy, Case 932, Aix-Marseille Université, CNRS UMR 6098, 13288 Marseille Cedex 09, France
| | - Eric Cascales
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, Institut de Microbiologie de la Méditerranée, CNRS, UMR 7255, Aix-Marseille Université, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France
| | - Laure Journet
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, Institut de Microbiologie de la Méditerranée, CNRS, UMR 7255, Aix-Marseille Université, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France.
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Silverman JM, Agnello DM, Zheng H, Andrews BT, Li M, Catalano CE, Gonen T, Mougous JD. Haemolysin coregulated protein is an exported receptor and chaperone of type VI secretion substrates. Mol Cell 2013; 51:584-93. [PMID: 23954347 DOI: 10.1016/j.molcel.2013.07.025] [Citation(s) in RCA: 205] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2013] [Revised: 06/27/2013] [Accepted: 07/25/2013] [Indexed: 10/26/2022]
Abstract
Secretion systems require high-fidelity mechanisms to discriminate substrates among the vast cytoplasmic pool of proteins. Factors mediating substrate recognition by the type VI secretion system (T6SS) of Gram-negative bacteria, a widespread pathway that translocates effector proteins into target bacterial cells, have not been defined. We report that haemolysin coregulated protein (Hcp), a ring-shaped hexamer secreted by all characterized T6SSs, binds specifically to cognate effector molecules. Electron microscopy analysis of an Hcp-effector complex from Pseudomonas aeruginosa revealed the effector bound to the inner surface of Hcp. Further studies demonstrated that interaction with the Hcp pore is a general requirement for secretion of diverse effectors encompassing several enzymatic classes. Though previous models depict Hcp as a static conduit, our data indicate it is a chaperone and receptor of substrates. These unique functions of a secreted protein highlight fundamental differences between the export mechanism of T6 and other characterized secretory pathways.
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Affiliation(s)
- Julie M Silverman
- Department of Microbiology, University of Washington, Seattle, WA 98195, USA
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36
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Lin JS, Ma LS, Lai EM. Systematic dissection of the agrobacterium type VI secretion system reveals machinery and secreted components for subcomplex formation. PLoS One 2013; 8:e67647. [PMID: 23861778 PMCID: PMC3702570 DOI: 10.1371/journal.pone.0067647] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2012] [Accepted: 05/22/2013] [Indexed: 11/18/2022] Open
Abstract
The type VI secretion system (T6SS) is widely distributed in pathogenic Proteobacteria. Sequence and structural analysis of T6SS reveals a resemblance to the T4 bacteriophage tail, in which an outer sheath structure contracts an internal tube for injecting nucleic acid into bacterial cells. However, the molecular details of how this phage tail-like T6SS structure is assembled in vivo and executed for exoprotein or effector secretion remain largely unknown. Here, we used a systematic approach to identify T6SS machinery and secreted components and investigate the interaction among the putative sheath and tube components of Agrobacterium tumefaciens. We showed that 14 T6SS components play essential roles in the secretion of the T6SS hallmark exoprotein Hcp. In addition, we discovered a novel T6SS exoprotein, Atu4347, that is dispensable for Hcp secretion. Interestingly, Atu4347 and the putative tube components, Hcp and VgrG, are mainly localized in the cytoplasm but also detected on the bacterial surface. Atu4342 (TssB) and Atu4341 (TssC41) interact with and stabilize each other, which suggests that they are functional orthologs of the sheath components TssB (VipA) and TssC (VipB), respectively. Importantly, TssB interacts directly with the three exoproteins (Hcp, VgrG, and Atu4347), in which Hcp also interacts directly with VgrG-1 on co-purification from Escherichia coli. Further co-immunoprecipitation and pulldown assays revealed these subcomplex(es) in A. tumefaciens and thereby support T6SS functioning as a contractile phage tail-like structure.
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Affiliation(s)
- Jer-Sheng Lin
- Institute of Plant and Microbial Biology, Academia Sinica, Taipei, Taiwan
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Carruthers MD, Nicholson PA, Tracy EN, Munson RS. Acinetobacter baumannii utilizes a type VI secretion system for bacterial competition. PLoS One 2013; 8:e59388. [PMID: 23527179 PMCID: PMC3602014 DOI: 10.1371/journal.pone.0059388] [Citation(s) in RCA: 95] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Accepted: 02/14/2013] [Indexed: 11/18/2022] Open
Abstract
Type VI secretion systems (T6SS) are a class of macromolecular secretion machines that are utilized by a number of bacteria for inter-bacterial competition or to elicit responses in eukaryotic cells. Acinetobacter baumannii is an opportunistic pathogen that causes severe infections in humans. These infections, including pneumonia and bacteremia, are important, as they are often associated with hospitals and medical-settings where they disproportionally affect critically ill patients like those residing in intensive care units. While it is known that A. baumannii genomes carry genes whose predicted products have homology with T6SS-associated gene products from other bacteria, and secretion of a major T6SS structural protein Hcp has been demonstrated, no additional work on an A. baumannii T6SS has been reported. Herein, we demonstrated that A. baumannii strain M2 secretes Hcp and this secretion was dependent upon TssB, an ortholog of a bacteriophage contractile sheath protein, confirming that strain M2 produces a functional T6SS. Additionally, we demonstrated that the ability of strain M2 to out-compete Escherichia coli was reliant upon the products of tssB and hcp. Collectively, our data have provided the first evidence demonstrating function in inter-bacterial competition, for a T6SS produced by A. baumannii.
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Affiliation(s)
- Michael D. Carruthers
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children’s Hospital and Department of Pediatrics, College of Medicine, The Center for Microbial Interface Biology, The Ohio State University, Columbus, Ohio, United States of America
| | - Paul A. Nicholson
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children’s Hospital and Department of Pediatrics, College of Medicine, The Center for Microbial Interface Biology, The Ohio State University, Columbus, Ohio, United States of America
| | - Erin N. Tracy
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children’s Hospital and Department of Pediatrics, College of Medicine, The Center for Microbial Interface Biology, The Ohio State University, Columbus, Ohio, United States of America
| | - Robert S. Munson
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children’s Hospital and Department of Pediatrics, College of Medicine, The Center for Microbial Interface Biology, The Ohio State University, Columbus, Ohio, United States of America
- * E-mail:
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Phenotypic characterization, virulence, and immunogenicity of Edwardsiella tarda LSE40 aroA mutant. Appl Microbiol Biotechnol 2013; 97:6325-35. [DOI: 10.1007/s00253-013-4813-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2012] [Revised: 02/15/2013] [Accepted: 02/24/2013] [Indexed: 12/31/2022]
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Effantin G, Hamasaki R, Kawasaki T, Bacia M, Moriscot C, Weissenhorn W, Yamada T, Schoehn G. Cryo-Electron Microscopy Three-Dimensional Structure of the Jumbo Phage ΦRSL1 Infecting the Phytopathogen Ralstonia solanacearum. Structure 2013; 21:298-305. [DOI: 10.1016/j.str.2012.12.017] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2012] [Revised: 12/04/2012] [Accepted: 12/18/2012] [Indexed: 01/30/2023]
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40
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Aschtgen MS, Zoued A, Lloubès R, Journet L, Cascales E. The C-tail anchored TssL subunit, an essential protein of the enteroaggregative Escherichia coli Sci-1 Type VI secretion system, is inserted by YidC. Microbiologyopen 2012; 1:71-82. [PMID: 22950014 PMCID: PMC3426401 DOI: 10.1002/mbo3.9] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2011] [Revised: 12/19/2011] [Accepted: 12/21/2011] [Indexed: 01/09/2023] Open
Abstract
Type VI secretion systems (T6SS) are macromolecular complexes present in Gram-negative bacteria. T6SS are structurally similar to the bacteriophage cell-puncturing device and have been shown to mediate bacteria–host or bacteria–bacteria interactions. T6SS assemble from 13 to 20 proteins. In enteroaggregative Escherichia coli (EAEC), one of the subassemblies is composed of four proteins that form a trans-envelope complex: the TssJ outer membrane lipoprotein, the peptidoglycan-anchored inner membrane TagL protein, and two putative inner membrane proteins, TssL and TssM. In this study, we characterized the TssL protein of the EAEC Sci-1 T6SS in terms of localization, topology, and function. TssL is a critical component of the T6SS, anchored to the inner membrane through a single transmembrane segment located at the extreme C-terminus of the protein. We further show that this transmembrane segment is essential for the function of the protein and its proper insertion in the inner membrane is dependent upon YidC and modulated by the Hsp70 homologue DnaK.
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Affiliation(s)
- Marie-Stéphanie Aschtgen
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, Institut de Microbiologie de la Méditerranée, Aix-Marseille Université CNRS - UMR 7255, 31 chemin Joseph Aiguier, 13402, Marseille Cedex 20, France
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41
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Silverman JM, Brunet YR, Cascales E, Mougous JD. Structure and regulation of the type VI secretion system. Annu Rev Microbiol 2012; 66:453-72. [PMID: 22746332 DOI: 10.1146/annurev-micro-121809-151619] [Citation(s) in RCA: 272] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The type VI secretion system (T6SS) is a complex and widespread gram-negative bacterial export pathway with the capacity to translocate protein effectors into a diversity of target cell types. Current structural models of the T6SS indicate that the apparatus is composed of at least two complexes, a dynamic bacteriophage-like structure and a cell-envelope-spanning membrane-associated assembly. How these complexes interact to promote effector secretion and cell targeting remains a major question in the field. As a contact-dependent pathway with specific cellular targets, the T6SS is subject to tight regulation. Thus, the identification of regulatory elements that control T6S expression continues to shape our understanding of the environmental circumstances relevant to its function. This review discusses recent progress toward characterizing T6S structure and regulation.
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Affiliation(s)
- Julie M Silverman
- Department of Microbiology, University of Washington, Seattle, 98195, USA
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Cascales E, Cambillau C. Structural biology of type VI secretion systems. Philos Trans R Soc Lond B Biol Sci 2012; 367:1102-11. [PMID: 22411981 DOI: 10.1098/rstb.2011.0209] [Citation(s) in RCA: 163] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Type VI secretion systems (T6SSs) are transenvelope complexes specialized in the transport of proteins or domains directly into target cells. These systems are versatile as they can target either eukaryotic host cells and therefore modulate the bacteria-host interaction and pathogenesis or bacterial cells and therefore facilitate access to a specific niche. These molecular machines comprise at least 13 proteins. Although recent years have witnessed advances in the role and function of these secretion systems, little is known about how these complexes assemble in the cell envelope. Interestingly, the current information converges to the idea that T6SSs are composed of two subassemblies, one resembling the contractile bacteriophage tail, whereas the other subunits are embedded in the inner and outer membranes and anchor the bacteriophage-like structure to the cell envelope. In this review, we summarize recent structural information on individual T6SS components emphasizing the fact that T6SSs are composite systems, adapting subunits from various origins.
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Affiliation(s)
- Eric Cascales
- CNRS, Laboratoire d'Ingénierie des Systèmes Macromoléculaires, UMR 7255, Institut de Microbiologie de la Méditerranée, Aix-Marseille Université, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France.
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Ma LS, Narberhaus F, Lai EM. IcmF family protein TssM exhibits ATPase activity and energizes type VI secretion. J Biol Chem 2012; 287:15610-21. [PMID: 22393043 PMCID: PMC3346141 DOI: 10.1074/jbc.m111.301630] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The type VI secretion system (T6SS) with diversified functions is widely distributed in pathogenic Proteobacteria. The IcmF (intracellular multiplication protein F) family protein TssM is a conserved T6SS inner membrane protein. Despite the conservation of its Walker A nucleotide-binding motif, the NTPase activity of TssM and its role in T6SS remain obscure. In this study, we characterized TssM in the plant pathogen Agrobacterium tumefaciens and provided the first biochemical evidence for TssM exhibiting ATPase activity to power the secretion of the T6SS hallmark protein, hemolysin-coregulated protein (Hcp). Amino acid substitutions in the Walker A motif of TssM caused reduced ATP binding and hydrolysis activity. Importantly, we discovered the Walker B motif of TssM and demonstrated that it is critical for ATP hydrolysis activity. Protein-protein interaction studies and protease susceptibility assays indicated that TssM undergoes an ATP binding-induced conformational change and that subsequent ATP hydrolysis is crucial for recruiting Hcp to interact with the periplasmic domain of the TssM-interacting protein TssL (an IcmH/DotU family protein) into a ternary complex and mediating Hcp secretion. Our findings strongly argue that TssM functions as a T6SS energizer to recruit Hcp into the TssM-TssL inner membrane complex prior to Hcp secretion across the outer membrane.
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Affiliation(s)
- Lay-Sun Ma
- Institute of Plant and Microbial Biology and the Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, Academia Sinica, Taipei 11529, Taiwan
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Leung KY, Siame BA, Tenkink BJ, Noort RJ, Mok YK. Edwardsiella tarda – Virulence mechanisms of an emerging gastroenteritis pathogen. Microbes Infect 2012; 14:26-34. [DOI: 10.1016/j.micinf.2011.08.005] [Citation(s) in RCA: 138] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2011] [Revised: 08/13/2011] [Accepted: 08/17/2011] [Indexed: 11/25/2022]
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Records AR. The type VI secretion system: a multipurpose delivery system with a phage-like machinery. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2011; 24:751-757. [PMID: 21361789 DOI: 10.1094/mpmi-11-10-0262] [Citation(s) in RCA: 109] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Whether they live in the soil, drift in the ocean, survive in the lungs of human hosts or reside on the surfaces of leaves, all bacteria must cope with an array of environmental stressors. Bacteria have evolved an impressive suite of protein secretion systems that enable their survival in hostile environments and facilitate colonization of eukaryotic hosts. Collectively, gram-negative bacteria produce six distinct secretion systems that deliver proteins to the extracellular milieu or directly into the cytosol of host cells. The type VI secretion system (T6SS) was discovered recently and is encoded in at least one fourth of all sequenced gram-negative bacterial genomes. T6SS proteins are evolutionarily and structurally related to phage proteins, and it is likely that the T6SS apparatus is reminiscent of phage injection machinery. Most studies of T6SS function have been conducted in the context of host-pathogen interactions. However, the totality of data suggests that the T6SS is a versatile tool with roles in virulence, symbiosis, interbacterial interactions, and antipathogenesis. This review gives a brief history of T6SS discovery and an overview of the pathway's predicted structure and function. Special attention is paid to research addressing the T6SS of plant-associated bacteria, including pathogens, symbionts and plant growth-promoting rhizobacteria.
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Affiliation(s)
- Angela R Records
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD, USA.
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Regulation of the Edwardsiella ictaluri type III secretion system by pH and phosphate concentration through EsrA, EsrB, and EsrC. Appl Environ Microbiol 2011; 77:4293-302. [PMID: 21551284 DOI: 10.1128/aem.00195-11] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A recently described Edwardsiella ictaluri type III secretion system (T3SS) with functional similarity to the Salmonella pathogenicity island 2 T3SS is required for replication in channel catfish head-kidney-derived macrophages (HKDM) and virulence in channel catfish. Quantitative PCR and Western blotting identified low pH and phosphate limitation as conducive to expression of the E. ictaluri T3SS, growth conditions that mimic the phagosomal environment. Mutagenesis studies demonstrated that expression is under the control of the EsrAB two-component regulatory system. EsrB also induces upregulation of the AraC-type regulatory protein EsrC, which enhances expression of the EscB/EseG chaperone/effector operon in concert with EsrB and induces expression of the pEI1-encoded effector, EseH. EsrC also induces expression of a putative type VI secretion system translocon protein, EvpC, which is secreted under the same low-pH conditions as the T3SS translocon proteins. The pEI2-encoded effector, EseI, was upregulated under low-pH and low-phosphate conditions but not in an EsrB- or EsrC-dependent manner. Mutations of EsrA and EsrB both resulted in loss of the ability to replicate in HKDM and full attenuation in the channel catfish host. Mutation of EsrC did not affect intracellular replication but did result in attenuation in catfish. Although EsrB is the primary transcriptional regulator for E. ictaluri genes within the T3SS pathogenicity island, EsrC regulates expression of the plasmid-carried effector eseH and appears to mediate coordinated expression of the T6SS with the T3SS.
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Crystal structure of secretory protein Hcp3 from Pseudomonas aeruginosa. ACTA ACUST UNITED AC 2011; 12:21-6. [PMID: 21476004 DOI: 10.1007/s10969-011-9107-1] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2010] [Accepted: 03/21/2011] [Indexed: 10/18/2022]
Abstract
The Type VI secretion pathway transports proteins across the cell envelope of Gram-negative bacteria. Pseudomonas aeruginosa, an opportunistic Gram-negative bacterial pathogen infecting humans, uses the type VI secretion pathway to export specific effector proteins crucial for its pathogenesis. The HSI-I virulence locus encodes for several proteins that has been proposed to participate in protein transport including the Hcp1 protein, which forms hexameric rings that assemble into nanotubes in vitro. Two Hcp1 paralogues have been identified in the P. aeruginosa genome, Hsp2 and Hcp3. Here, we present the structure of the Hcp3 protein from P. aeruginosa. The overall structure of the monomer resembles Hcp1 despite the lack of amino-acid sequence similarity between the two proteins. The monomers assemble into hexamers similar to Hcp1. However, instead of forming nanotubes in head-to-tail mode like Hcp1, Hcp3 stacks its rings in head-to-head mode forming double-ring structures.
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