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Costa TRD, Patkowski JB, Macé K, Christie PJ, Waksman G. Structural and functional diversity of type IV secretion systems. Nat Rev Microbiol 2024; 22:170-185. [PMID: 37814112 PMCID: PMC11290344 DOI: 10.1038/s41579-023-00974-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 13.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/13/2023] [Indexed: 10/11/2023]
Abstract
Considerable progress has been made in recent years in the structural and molecular biology of type IV secretion systems in Gram-negative bacteria. The latest advances have substantially improved our understanding of the mechanisms underlying the recruitment and delivery of DNA and protein substrates to the extracellular environment or target cells. In this Review, we aim to summarize these exciting structural and molecular biology findings and to discuss their functional implications for substrate recognition, recruitment and translocation, as well as the biogenesis of extracellular pili. We also describe adaptations necessary for deploying a breadth of processes, such as bacterial survival, host-pathogen interactions and biotic and abiotic adhesion. We highlight the functional and structural diversity that allows this extremely versatile secretion superfamily to function under different environmental conditions and in different bacterial species. Additionally, we emphasize the importance of further understanding the mechanism of type IV secretion, which will support us in combating antimicrobial resistance and treating type IV secretion system-related infections.
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Affiliation(s)
- Tiago R D Costa
- Centre for Bacterial Resistance Biology, Department of Life Sciences, Imperial College, London, UK.
| | - Jonasz B Patkowski
- Centre for Bacterial Resistance Biology, Department of Life Sciences, Imperial College, London, UK
| | - Kévin Macé
- Institute of Structural and Molecular Biology, Birkbeck and UCL, London, UK
- Institut de Génétique et Développement de Rennes (IGDR), Université de Rennes and CNRS, Rennes, France
| | - Peter J Christie
- Department of Microbiology and Molecular Genetics, McGovern Medical School at UTHealth, Houston, TX, USA.
| | - Gabriel Waksman
- Institute of Structural and Molecular Biology, Birkbeck and UCL, London, UK.
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2
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Ignatiou A, Macé K, Redzej A, Costa TRD, Waksman G, Orlova EV. Structural Analysis of Protein Complexes by Cryo-Electron Microscopy. Methods Mol Biol 2024; 2715:431-470. [PMID: 37930544 DOI: 10.1007/978-1-0716-3445-5_27] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2023]
Abstract
Structural studies of bio-complexes using single particle cryo-Electron Microscopy (cryo-EM) is nowadays a well-established technique in structural biology and has become competitive with X-ray crystallography. Development of digital registration systems for electron microscopy images and algorithms for the fast and efficient processing of the recorded images and their following analysis has facilitated the determination of structures at near-atomic resolution. The latest advances in EM have enabled the determination of protein complex structures at 1.4-3 Å resolution for an extremely broad range of sizes (from ~100 kDa up to hundreds of MDa (Bartesaghi et al., Science 348(6239):1147-1151, 2015; Herzik et al., Nat Commun 10:1032, 2019; Wu et al., J Struct Biol X 4:100020, 2020; Zhang et al., Nat Commun 10:5511, 2019; Zhang et al., Cell Res 30(12):1136-1139, 2020; Yip et al., Nature 587(7832):157-161, 2020; https://www.ebi.ac.uk/emdb/statistics/emdb_resolution_year )). In 2022, nearly 1200 structures deposited to the EMDB database were at a resolution of better than 3 Å ( https://www.ebi.ac.uk/emdb/statistics/emdb_resolution_year ).To date, the highest resolutions have been achieved for apoferritin, which comprises a homo-oligomer of high point group symmetry (O432) and has rigid organization together with high stability (Zhang et al., Cell Res 30(12):1136-1139, 2020; Yip et al., Nature 587(7832):157-161, 2020). It has been used as a test object for the assessments of modern cryo-microscopes and processing methods during the last 5 years. In contrast to apoferritin bacterial secretion systems are typical examples of multi protein complexes exhibiting high flexibility owing to their functions relating to the transportation of small molecules, proteins, and DNA into the extracellular space or target cells. This makes their structural characterization extremely challenging (Barlow, Methods Mol Biol 532:397-411, 2009; Costa et al., Nat Rev Microbiol 13:343-359, 2015). The most feasible approach to reveal their spatial organization and functional modification is cryo-electron microscopy (EM). During the last decade, structural cryo-EM has become broadly used for the analysis of the bio-complexes that comprise multiple components and are not amenable to crystallization (Lyumkis, J Biol Chem 294:5181-5197, 2019; Orlova and Saibil, Methods Enzymol 482:321-341, 2010; Orlova and Saibil, Chem Rev 111(12):7710-7748, 2011).In this review, we will describe the basics of sample preparation for cryo-EM, the principles of digital data collection, and the logistics of image analysis focusing on the common steps required for reconstructions of both small and large biological complexes together with refinement of their structures to nearly atomic resolution. The workflow of processing will be illustrated by examples of EM analysis of Type IV Secretion System.
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Affiliation(s)
- Athanasios Ignatiou
- Institute for Structural and Molecular Biology, School of Biological Sciences, Birkbeck College, London, UK
| | - Kévin Macé
- Institute for Structural and Molecular Biology, School of Biological Sciences, Birkbeck College, London, UK
| | - Adam Redzej
- Institute for Structural and Molecular Biology, School of Biological Sciences, Birkbeck College, London, UK
| | - Tiago R D Costa
- Centre for Bacterial Resistance Biology, Department of Life Sciences, Imperial College, London, UK
| | - Gabriel Waksman
- Institute for Structural and Molecular Biology, School of Biological Sciences, Birkbeck College, London, UK
| | - Elena V Orlova
- Institute for Structural and Molecular Biology, School of Biological Sciences, Birkbeck College, London, UK.
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3
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Tran SC, McClain MS, Cover TL. Role of the CagY antenna projection in Helicobacter pylori Cag type IV secretion system activity. Infect Immun 2023; 91:e0015023. [PMID: 37638724 PMCID: PMC10501215 DOI: 10.1128/iai.00150-23] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Accepted: 07/07/2023] [Indexed: 08/29/2023] Open
Abstract
Helicobacter pylori strains containing the cag pathogenicity island (PAI) are associated with the development of gastric adenocarcinoma and peptic ulcer disease. The cag PAI encodes a secreted effector protein (CagA) and a type IV secretion system (Cag T4SS). Cag T4SS activity is required for the delivery of CagA and non-protein substrates into host cells. The Cag T4SS outer membrane core complex (OMCC) contains a channel-like domain formed by helix-loop-helix elements (antenna projections, AP) from 14 copies of the CagY protein (a VirB10 ortholog). Similar VirB10 antenna regions are present in T4SS OMCCs from multiple bacterial species and are predicted to span the outer membrane. In this study, we investigated the role of the CagY antenna region in Cag T4SS OMCC assembly and Cag T4SS function. An H. pylori mutant strain with deletion of the entire CagY AP (∆AP) retained the capacity to produce CagY and assemble an OMCC, but it lacked T4SS activity (CagA translocation and IL-8 induction in AGS gastric epithelial cells). In contrast, a mutant strain with Gly-Ser substitutions in the unstructured CagY AP loop retained Cag T4SS activity. Mutants containing CagY AP loops with shortened lengths were defective in CagA translocation and exhibited reduced IL-8-inducing activity compared to control strains. These data indicate that the CagY AP region is required for Cag T4SS activity and that Cag T4SS activity can be modulated by altering the length of the CagY AP unstructured loop.
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Affiliation(s)
- Sirena C. Tran
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Mark S. McClain
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Timothy L. Cover
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, USA
- Vanderbilt Institute for Infection, Immunology, and Inflammation, Vanderbilt University Medical Center, Nashville, Tennessee, USA
- Veterans Affairs Tennessee Valley Healthcare System, Nashville, Tennessee, USA
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Ahdritz G, Bouatta N, Kadyan S, Jarosch L, Berenberg D, Fisk I, Watkins AM, Ra S, Bonneau R, AlQuraishi M. OpenProteinSet: Training data for structural biology at scale. ARXIV 2023:arXiv:2308.05326v1. [PMID: 37608940 PMCID: PMC10441447] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Subscribe] [Scholar Register] [Indexed: 08/24/2023]
Abstract
Multiple sequence alignments (MSAs) of proteins encode rich biological information and have been workhorses in bioinformatic methods for tasks like protein design and protein structure prediction for decades. Recent breakthroughs like AlphaFold2 that use transformers to attend directly over large quantities of raw MSAs have reaffirmed their importance. Generation of MSAs is highly computationally intensive, however, and no datasets comparable to those used to train AlphaFold2 have been made available to the research community, hindering progress in machine learning for proteins. To remedy this problem, we introduce OpenProteinSet, an open-source corpus of more than 16 million MSAs, associated structural homologs from the Protein Data Bank, and AlphaFold2 protein structure predictions. We have previously demonstrated the utility of OpenProteinSet by successfully retraining AlphaFold2 on it. We expect OpenProteinSet to be broadly useful as training and validation data for 1) diverse tasks focused on protein structure, function, and design and 2) large-scale multimodal machine learning research.
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Affiliation(s)
| | - Nazim Bouatta
- Laboratory of Systems Pharmacology, Harvard Medical School
| | | | | | - Daniel Berenberg
- Prescient Design, Genentech & Department of Computer Science, New York University
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5
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Ryan ME, Damke PP, Bryant C, Sheedlo MJ, Shaffer CL. Architectural asymmetry enables DNA transport through the Helicobacter pylori cag type IV secretion system. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.25.550604. [PMID: 37546756 PMCID: PMC10402047 DOI: 10.1101/2023.07.25.550604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/08/2023]
Abstract
Structural asymmetry within secretion system architecture is fundamentally important for apparatus diversification and biological function. However, the mechanism by which symmetry mismatch contributes to nanomachine assembly and interkingdom effector translocation are undefined. Here, we show that architectural asymmetry orchestrates dynamic substrate selection and enables trans-kingdom DNA conjugation through the Helicobacter pylori cag type IV secretion system (cag T4SS). Structural analyses of asymmetric units within the cag T4SS periplasmic ring complex (PRC) revealed intermolecular π-π stacking interactions that coordinate DNA binding and license trans-kingdom conjugation without disrupting the translocation of protein and peptidoglycan effector molecules. Additionally, we identified a novel proximal translocation channel gating mechanism that regulates cargo loading and governs substrate transport across the outer membrane. We thus propose a model whereby the organization and geometry of architectural symmetry mismatch exposes π-π interfaces within the PRC to facilitate DNA transit through the cag T4SS translocation channel.
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Affiliation(s)
- Mackenzie E. Ryan
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky College of Medicine, Lexington, KY, 40506, USA
| | - Prashant P. Damke
- Department of Veterinary Sciences, University of Kentucky College of Agriculture, Lexington, KY, 40546, USA
| | - Caitlynn Bryant
- Department of Veterinary Sciences, University of Kentucky College of Agriculture, Lexington, KY, 40546, USA
| | - Michael J. Sheedlo
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, 55455, USA
| | - Carrie L. Shaffer
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky College of Medicine, Lexington, KY, 40506, USA
- Department of Veterinary Sciences, University of Kentucky College of Agriculture, Lexington, KY, 40546, USA
- Department of Pharmaceutical Sciences, University of Kentucky College of Pharmacy, Lexington, KY, 40536, USA
- Markey Cancer Center, University of Kentucky College of Medicine, Lexington, KY, 40506, USA
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6
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Ryan ME, Damke PP, Shaffer CL. DNA Transport through the Dynamic Type IV Secretion System. Infect Immun 2023; 91:e0043622. [PMID: 37338415 PMCID: PMC10353360 DOI: 10.1128/iai.00436-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/21/2023] Open
Abstract
The versatile type IV secretion system (T4SS) nanomachine plays a pivotal role in bacterial pathogenesis and the propagation of antibiotic resistance determinants throughout microbial populations. In addition to paradigmatic DNA conjugation machineries, diverse T4SSs enable the delivery of multifarious effector proteins to target prokaryotic and eukaryotic cells, mediate DNA export and uptake from the extracellular milieu, and in rare examples, facilitate transkingdom DNA translocation. Recent advances have identified new mechanisms underlying unilateral nucleic acid transport through the T4SS apparatus, highlighting both functional plasticity and evolutionary adaptations that enable novel capabilities. In this review, we describe the molecular mechanisms underscoring DNA translocation through diverse T4SS machineries, emphasizing the architectural features that implement DNA exchange across the bacterial membrane and license transverse DNA release across kingdom boundaries. We further detail how recent studies have addressed outstanding questions surrounding the mechanisms by which nanomachine architectures and substrate recruitment strategies contribute to T4SS functional diversity.
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Affiliation(s)
- Mackenzie E. Ryan
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky College of Medicine, Lexington, Kentucky, USA
| | - Prashant P. Damke
- Department of Veterinary Sciences, University of Kentucky College of Agriculture, Lexington, Kentucky, USA
| | - Carrie L. Shaffer
- Department of Microbiology, Immunology, and Molecular Genetics, University of Kentucky College of Medicine, Lexington, Kentucky, USA
- Department of Veterinary Sciences, University of Kentucky College of Agriculture, Lexington, Kentucky, USA
- Department of Pharmaceutical Sciences, University of Kentucky College of Pharmacy, Lexington, Kentucky, USA
- Markey Cancer Center, University of Kentucky College of Medicine, Lexington, Kentucky, USA
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7
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Abstract
Bacterial type IV secretion systems (T4SSs) are a versatile group of nanomachines that can horizontally transfer DNA through conjugation and deliver effector proteins into a wide range of target cells. The components of T4SSs in gram-negative bacteria are organized into several large subassemblies: an inner membrane complex, an outer membrane core complex, and, in some species, an extracellular pilus. Cryo-electron tomography has been used to define the structures of T4SSs in intact bacteria, and high-resolution structural models are now available for isolated core complexes from conjugation systems, the Xanthomonas citri T4SS, the Helicobacter pylori Cag T4SS, and the Legionella pneumophila Dot/Icm T4SS. In this review, we compare the molecular architectures of these T4SSs, focusing especially on the structures of core complexes. We discuss structural features that are shared by multiple T4SSs as well as evolutionary strategies used for T4SS diversification. Finally, we discuss how structural variations among T4SSs may confer specialized functional properties.
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Affiliation(s)
- Michael J. Sheedlo
- Department of Pharmacology, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - Melanie D. Ohi
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, Michigan, United States of America
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan, United States of America
| | - D. Borden Lacy
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Veterans Affairs Tennessee Valley Healthcare System, Nashville, Tennessee, United States of America
| | - Timothy L. Cover
- Department of Pathology, Microbiology, and Immunology, Vanderbilt University Medical Center, Nashville, Tennessee, United States of America
- Veterans Affairs Tennessee Valley Healthcare System, Nashville, Tennessee, United States of America
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee, United States of America
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8
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Cheng E, Dorjsuren D, Lehman S, Larson CL, Titus SA, Sun H, Zakharov A, Rai G, Heinzen RA, Simeonov A, Machner MP. A Comprehensive Phenotypic Screening Strategy to Identify Modulators of Cargo Translocation by the Bacterial Type IVB Secretion System. mBio 2022; 13:e0024022. [PMID: 35258332 PMCID: PMC9040768 DOI: 10.1128/mbio.00240-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Accepted: 02/08/2022] [Indexed: 02/03/2023] Open
Abstract
Bacterial type IV secretion systems (T4SSs) are macromolecular machines that translocate effector proteins across multiple membranes into infected host cells. Loss of function mutations in genes encoding protein components of the T4SS render bacteria avirulent, highlighting the attractiveness of T4SSs as drug targets. Here, we designed an automated high-throughput screening approach for the identification of compounds that interfere with the delivery of a reporter-effector fusion protein from Legionella pneumophila into RAW264.7 mouse macrophages. Using a fluorescence resonance energy transfer (FRET)-based detection assay in a bacteria/macrophage coculture format, we screened a library of over 18,000 compounds and, upon vetting compound candidates in a variety of in vitro and cell-based secondary screens, isolated several hits that efficiently interfered with biological processes that depend on a functional T4SS, such as intracellular bacterial proliferation or lysosomal avoidance, but had no detectable effect on L. pneumophila growth in culture medium, conditions under which the T4SS is dispensable. Notably, the same hit compounds also attenuated, to varying degrees, effector delivery by the closely related T4SS from Coxiella burnetii, notably without impacting growth of this organism within synthetic media. Together, these results support the idea that interference with T4SS function is a possible therapeutic intervention strategy, and the emerging compounds provide tools to interrogate at a molecular level the regulation and dynamics of these virulence-critical translocation machines. IMPORTANCE Multi-drug-resistant pathogens are an emerging threat to human health. Because conventional antibiotics target not only the pathogen but also eradicate the beneficial microbiota, they often cause additional clinical complications. Thus, there is an urgent need for the development of "smarter" therapeutics that selectively target pathogens without affecting beneficial commensals. The bacterial type IV secretion system (T4SS) is essential for the virulence of a variety of pathogens but dispensable for bacterial viability in general and can, thus, be considered a pathogen's Achilles heel. By identifying small molecules that interfere with cargo delivery by the T4SS from two important human pathogens, Legionella pneumophila and Coxiella burnetii, our study represents the first step in our pursuit toward precision medicine by developing pathogen-selective therapeutics capable of treating the infections without causing harm to commensal bacteria.
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Affiliation(s)
- Eric Cheng
- Division of Molecular and Cellular Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA
| | - Dorjbal Dorjsuren
- Division of Preclinical Innovation, National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland, USA
| | - Stephanie Lehman
- Division of Molecular and Cellular Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA
| | - Charles L. Larson
- Laboratory of Bacteriology, Coxiella Pathogenesis Section, National Institute of Allergy and Infectious Diseases, Rocky Mountain Laboratories, Hamilton, Montana, USA
| | - Steven A. Titus
- Division of Preclinical Innovation, National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland, USA
| | - Hongmao Sun
- Division of Preclinical Innovation, National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland, USA
| | - Alexey Zakharov
- Division of Preclinical Innovation, National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland, USA
| | - Ganesha Rai
- Division of Preclinical Innovation, National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland, USA
| | - Robert A. Heinzen
- Laboratory of Bacteriology, Coxiella Pathogenesis Section, National Institute of Allergy and Infectious Diseases, Rocky Mountain Laboratories, Hamilton, Montana, USA
| | - Anton Simeonov
- Division of Preclinical Innovation, National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland, USA
| | - Matthias P. Machner
- Division of Molecular and Cellular Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA
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Amin H, Ilangovan A, Costa TRD. Architecture of the outer-membrane core complex from a conjugative type IV secretion system. Nat Commun 2021; 12:6834. [PMID: 34824240 PMCID: PMC8617172 DOI: 10.1038/s41467-021-27178-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Accepted: 11/03/2021] [Indexed: 11/30/2022] Open
Abstract
Conjugation is one of the most important processes that bacteria utilize to spread antibiotic resistance genes among bacterial populations. Interbacterial DNA transfer requires a large double membrane-spanning nanomachine called the type 4 secretion system (T4SS) made up of the inner-membrane complex (IMC), the outer-membrane core complex (OMCC) and the conjugative pilus. The iconic F plasmid-encoded T4SS has been central in understanding conjugation for several decades, however atomic details of its structure are not known. Here, we report the structure of a complete conjugative OMCC encoded by the pED208 plasmid from E. coli, solved by cryo-electron microscopy at 3.3 Å resolution. This 2.1 MDa complex has a unique arrangement with two radial concentric rings, each having a different symmetry eventually contributing to remarkable differences in protein stoichiometry and flexibility in comparison to other OMCCs. Our structure suggests that F-OMCC is a highly dynamic complex, with implications for pilus extension and retraction during conjugation.
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Affiliation(s)
- Himani Amin
- grid.7445.20000 0001 2113 8111MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College, London, SW7 2AZ UK
| | - Aravindan Ilangovan
- School of Biological and Chemical Sciences, Queen Mary University of London, London, E1 4NS, UK.
| | - Tiago R. D. Costa
- grid.7445.20000 0001 2113 8111MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College, London, SW7 2AZ UK
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10
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In Situ Visualization of the pKM101-Encoded Type IV Secretion System Reveals a Highly Symmetric ATPase Energy Center. mBio 2021; 12:e0246521. [PMID: 34634937 PMCID: PMC8510550 DOI: 10.1128/mbio.02465-21] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Bacterial conjugation systems are members of the type IV secretion system (T4SS) superfamily. T4SSs can be classified as “minimized” or “expanded” based on whether they are composed of a core set of signature subunits or additional system-specific components. Prototypical minimized systems mediating Agrobacterium tumefaciens transfer DNA (T-DNA) and pKM101 and R388 plasmid transfer are built from subunits generically named VirB1 to VirB11 and VirD4. We visualized the pKM101-encoded T4SS in its native cellular context by in situ cryo-electron tomography (CryoET). The T4SSpKM101 is composed of an outer membrane core complex (OMCC) connected by a thin stalk to an inner membrane complex (IMC). The OMCC exhibits 14-fold symmetry and resembles that of the T4SSR388 analyzed previously by single-particle electron microscopy. The IMC is highly symmetrical and exhibits 6-fold symmetry. It is dominated by a hexameric collar in the periplasm and a cytoplasmic complex composed of a hexamer of dimers of the VirB4-like TraB ATPase. The IMC closely resembles equivalent regions of three expanded T4SSs previously visualized by in situ CryoET but differs strikingly from the IMC of the purified T4SSR388, whose cytoplasmic complex instead presents as two side-by-side VirB4 hexamers. Analyses of mutant machines lacking each of the three ATPases required for T4SSpKM101 function supplied evidence that TraBB4 as well as VirB11-like TraG contribute to distinct stages of machine assembly. We propose that the VirB4-like ATPases, configured as hexamers of dimers at the T4SS entrance, orchestrate IMC assembly and recruitment of the spatially dynamic VirB11 and VirD4 ATPases to activate the T4SS for substrate transfer.
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11
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Burns DL. Secretion of Pertussis Toxin from Bordetella pertussis. Toxins (Basel) 2021; 13:toxins13080574. [PMID: 34437445 PMCID: PMC8402538 DOI: 10.3390/toxins13080574] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 08/12/2021] [Accepted: 08/16/2021] [Indexed: 11/24/2022] Open
Abstract
Production and secretion of pertussis toxin (PT) is essential for the virulence of Bordetella pertussis. Due to the large oligomeric structure of PT, transport of the toxin across bacterial membrane barriers represents a significant hurdle that the bacteria must overcome in order to maintain pathogenicity. During the secretion process, PT undergoes a two-step transport process. The first step involves transport of the individual polypeptide chains of PT across the inner membrane utilizing a generalized secretion pathway, most likely the bacterial Sec system. The second step involves the use of a specialized apparatus to transport the toxin across the outer membrane of the bacterial cell. This apparatus, which has been termed the Ptl transporter and which is unique to the PT secretion pathway, is a member of the type IV family of bacterial transporters. Here, the current understanding of the PT secretion process is reviewed including a description of the Ptl proteins that assemble to form the transporter, the general structure of type IV transporters, the known similarities and differences between canonical type IV substrate transport and Ptl-mediated transport of PT, as well as the known sequence of events in the assembly and secretion of PT.
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Affiliation(s)
- Drusilla L Burns
- Center for Biologics Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD 20993, USA
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12
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Grishin A, Voth K, Gagarinova A, Cygler M. Structural biology of the invasion arsenal of Gram-negative bacterial pathogens. FEBS J 2021; 289:1385-1427. [PMID: 33650300 DOI: 10.1111/febs.15794] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2020] [Revised: 02/11/2021] [Accepted: 02/26/2021] [Indexed: 12/20/2022]
Abstract
In the last several years, there has been a tremendous progress in the understanding of host-pathogen interactions and the mechanisms by which bacterial pathogens modulate behavior of the host cell. Pathogens use secretion systems to inject a set of proteins, called effectors, into the cytosol of the host cell. These effectors are secreted in a highly regulated, temporal manner and interact with host proteins to modify a multitude of cellular processes. The number of effectors varies between pathogens from ~ 30 to as many as ~ 350. The functional redundancy of effectors encoded by each pathogen makes it difficult to determine the cellular effects or function of individual effectors, since their individual knockouts frequently produce no easily detectable phenotypes. Structural biology of effector proteins and their interactions with host proteins, in conjunction with cell biology approaches, has provided invaluable information about the cellular function of effectors and underlying molecular mechanisms of their modes of action. Many bacterial effectors are functionally equivalent to host proteins while being structurally divergent from them. Other effector proteins display new, previously unobserved functionalities. Here, we summarize the contribution of the structural characterization of effectors and effector-host protein complexes to our understanding of host subversion mechanisms used by the most commonly investigated Gram-negative bacterial pathogens. We describe in some detail the enzymatic activities discovered among effector proteins and how they affect various cellular processes.
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Affiliation(s)
- Andrey Grishin
- Department of Biochemistry, Microbiology, & Immunology, University of Saskatchewan, Saskatoon, Canada
| | - Kevin Voth
- Department of Biochemistry, Microbiology, & Immunology, University of Saskatchewan, Saskatoon, Canada
| | - Alla Gagarinova
- Department of Biochemistry, Microbiology, & Immunology, University of Saskatchewan, Saskatoon, Canada
| | - Miroslaw Cygler
- Department of Biochemistry, Microbiology, & Immunology, University of Saskatchewan, Saskatoon, Canada
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13
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Costa TRD, Harb L, Khara P, Zeng L, Hu B, Christie PJ. Type IV secretion systems: Advances in structure, function, and activation. Mol Microbiol 2021; 115:436-452. [PMID: 33326642 DOI: 10.1111/mmi.14670] [Citation(s) in RCA: 105] [Impact Index Per Article: 35.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2020] [Revised: 12/12/2020] [Accepted: 12/13/2020] [Indexed: 12/14/2022]
Abstract
Bacterial type IV secretion systems (T4SSs) are a functionally diverse translocation superfamily. They consist mainly of two large subfamilies: (i) conjugation systems that mediate interbacterial DNA transfer and (ii) effector translocators that deliver effector macromolecules into prokaryotic or eukaryotic cells. A few other T4SSs export DNA or proteins to the milieu, or import exogenous DNA. The T4SSs are defined by 6 or 12 conserved "core" subunits that respectively elaborate "minimized" systems in Gram-positive or -negative bacteria. However, many "expanded" T4SSs are built from "core" subunits plus numerous others that are system-specific, which presumptively broadens functional capabilities. Recently, there has been exciting progress in defining T4SS assembly pathways and architectures using a combination of fluorescence and cryoelectron microscopy. This review will highlight advances in our knowledge of structure-function relationships for model Gram-negative bacterial T4SSs, including "minimized" systems resembling the Agrobacterium tumefaciens VirB/VirD4 T4SS and "expanded" systems represented by the Helicobacter pylori Cag, Legionella pneumophila Dot/Icm, and F plasmid-encoded Tra T4SSs. Detailed studies of these model systems are generating new insights, some at atomic resolution, to long-standing questions concerning mechanisms of substrate recruitment, T4SS channel architecture, conjugative pilus assembly, and machine adaptations contributing to T4SS functional versatility.
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Affiliation(s)
- Tiago R D Costa
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London, UK
| | - Laith Harb
- Department of Biochemistry and Biophysics and Center for Phage Technology, Texas A&M University, College Station, TX, USA
| | - Pratick Khara
- Department of Microbiology and Molecular Genetics, McGovern Medical School at UTHealth, Houston, TX, USA
| | - Lanying Zeng
- Department of Biochemistry and Biophysics and Center for Phage Technology, Texas A&M University, College Station, TX, USA
| | - Bo Hu
- Department of Microbiology and Molecular Genetics, McGovern Medical School at UTHealth, Houston, TX, USA
| | - Peter J Christie
- Department of Microbiology and Molecular Genetics, McGovern Medical School at UTHealth, Houston, TX, USA
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14
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Durie CL, Sheedlo MJ, Chung JM, Byrne BG, Su M, Knight T, Swanson M, Lacy DB, Ohi MD. Structural analysis of the Legionella pneumophila Dot/Icm type IV secretion system core complex. eLife 2020; 9:e59530. [PMID: 32876045 PMCID: PMC7511231 DOI: 10.7554/elife.59530] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Accepted: 09/01/2020] [Indexed: 01/21/2023] Open
Abstract
Legionella pneumophila is an opportunistic pathogen that causes the potentially fatal pneumonia Legionnaires' Disease. This infection and subsequent pathology require the Dot/Icm Type IV Secretion System (T4SS) to deliver effector proteins into host cells. Compared to prototypical T4SSs, the Dot/Icm assembly is much larger, containing ~27 different components including a core complex reported to be composed of five proteins: DotC, DotD, DotF, DotG, and DotH. Using single particle cryo-electron microscopy (cryo-EM), we report reconstructions of the core complex of the Dot/Icm T4SS that includes a symmetry mismatch between distinct structural features of the outer membrane cap (OMC) and periplasmic ring (PR). We present models of known core complex proteins, DotC, DotD, and DotH, and two structurally similar proteins within the core complex, DotK and Lpg0657. This analysis reveals the stoichiometry and contact interfaces between the key proteins of the Dot/Icm T4SS core complex and provides a framework for understanding a complex molecular machine.
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Affiliation(s)
- Clarissa L Durie
- Life Sciences Institute, University of MichiganAnn ArborUnited States
| | - Michael J Sheedlo
- Department of Pathology, Microbiology, and Immunology, Department of Pathology, Vanderbilt University Medical CenterNashvilleUnited States
| | - Jeong Min Chung
- Life Sciences Institute, University of MichiganAnn ArborUnited States
| | - Brenda G Byrne
- Department of Microbiology and Immunology, University of MichiganAnn ArborUnited States
| | - Min Su
- Life Sciences Institute, University of MichiganAnn ArborUnited States
| | - Thomas Knight
- Department of Microbiology and Immunology, University of MichiganAnn ArborUnited States
| | - Michele Swanson
- Department of Microbiology and Immunology, University of MichiganAnn ArborUnited States
| | - D Borden Lacy
- Department of Pathology, Microbiology, and Immunology, Department of Pathology, Vanderbilt University Medical CenterNashvilleUnited States
- The Veterans Affairs Tennessee Valley Healthcare SystemNashvilleUnited States
- Department of Cell and Developmental Biology, University of MichiganAnn ArborUnited States
| | - Melanie D Ohi
- Life Sciences Institute, University of MichiganAnn ArborUnited States
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15
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Bleriot I, Trastoy R, Blasco L, Fernández-Cuenca F, Ambroa A, Fernández-García L, Pacios O, Perez-Nadales E, Torre-Cisneros J, Oteo-Iglesias J, Navarro F, Miró E, Pascual A, Bou G, Martínez-Martínez L, Tomas M. Genomic analysis of 40 prophages located in the genomes of 16 carbapenemase-producing clinical strains of Klebsiella pneumoniae. Microb Genom 2020; 6:e000369. [PMID: 32375972 PMCID: PMC7371120 DOI: 10.1099/mgen.0.000369] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2019] [Accepted: 03/31/2020] [Indexed: 12/12/2022] Open
Abstract
Klebsiella pneumoniae is the clinically most important species within the genus Klebsiella and, as a result of the continuous emergence of multi-drug resistant (MDR) strains, the cause of severe nosocomial infections. The decline in the effectiveness of antibiotic treatments for infections caused by MDR bacteria has generated particular interest in the study of bacteriophages. In this study, we characterized a total of 40 temperate bacteriophages (prophages) with a genome range of 11.454-84.199 kb, predicted from 16 carbapenemase-producing clinical strains of K. pneumoniae belonging to different sequence types, previously identified by multilocus sequence typing. These prophages were grouped into the three families in the order Caudovirales (27 prophages belonging to the family Myoviridae, 10 prophages belonging to the family Siphoviridae and 3 prophages belonging to the family Podoviridae). Genomic comparison of the 40 prophage genomes led to the identification of four prophages isolated from different strains and of genome sizes of around 33.3, 36.1, 39.6 and 42.6 kb. These prophages showed sequence similarities (query cover >90 %, identity >99.9 %) with international Microbe Versus Phage (MVP) (http://mvp.medgenius.info/home) clusters 4762, 4901, 3499 and 4280, respectively. Phylogenetic analysis revealed the evolutionary proximity among the members of the four groups of the most frequently identified prophages in the bacterial genomes studied (33.3, 36.1, 39.6 and 42.6 kb), with bootstrap values of 100 %. This allowed the prophages to be classified into three clusters: A, B and C. Interestingly, these temperate bacteriophages did not infect the highest number of strains as indicated by a host-range assay, these results could be explained by the development of superinfection exclusion mechanisms. In addition, bioinformatic analysis of the 40 identified prophages revealed the presence of 2363 proteins. In total, 59.7 % of the proteins identified had a predicted function, mainly involving viral structure, transcription, replication and regulation (lysogenic/lysis). Interestingly, some proteins had putative functions associated with bacterial virulence (toxin expression and efflux pump regulators), phage defence profiles such as toxin-antitoxin modules, an anti-CRISPR/Cas9 protein, TerB protein (from terZABCDE operon) and methyltransferase proteins.
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Affiliation(s)
- Ines Bleriot
- Microbiology Department, Research Institute Biomedical A Coruña (INIBIC), Hospital A Coruña (CHUAC), University of A Coruña (UDC), A Coruña, Spain
- Study Group on Mechanisms of Action and Resistance to Antimicrobials (GEMARA), Spanish Society of Infectious Diseases and Clinical Microbiology (SEIMC), Madrid
| | - Rocío Trastoy
- Microbiology Department, Research Institute Biomedical A Coruña (INIBIC), Hospital A Coruña (CHUAC), University of A Coruña (UDC), A Coruña, Spain
- Study Group on Mechanisms of Action and Resistance to Antimicrobials (GEMARA), Spanish Society of Infectious Diseases and Clinical Microbiology (SEIMC), Madrid
| | - Lucia Blasco
- Microbiology Department, Research Institute Biomedical A Coruña (INIBIC), Hospital A Coruña (CHUAC), University of A Coruña (UDC), A Coruña, Spain
- Study Group on Mechanisms of Action and Resistance to Antimicrobials (GEMARA), Spanish Society of Infectious Diseases and Clinical Microbiology (SEIMC), Madrid
| | - Felipe Fernández-Cuenca
- Study Group on Mechanisms of Action and Resistance to Antimicrobials (GEMARA), Spanish Society of Infectious Diseases and Clinical Microbiology (SEIMC), Madrid
- Clinical Unit for Infectious Diseases, Microbiology and Preventive Medicine, Hospital Universitario Virgen Macarena. Deparment of Microbiology and Medicine, University of Seville, Seville, Spain
- Spanish Network for the Research in Infectious Diseases, REIPI, Seville, Spain
| | - Antón Ambroa
- Microbiology Department, Research Institute Biomedical A Coruña (INIBIC), Hospital A Coruña (CHUAC), University of A Coruña (UDC), A Coruña, Spain
- Study Group on Mechanisms of Action and Resistance to Antimicrobials (GEMARA), Spanish Society of Infectious Diseases and Clinical Microbiology (SEIMC), Madrid
| | - Laura Fernández-García
- Microbiology Department, Research Institute Biomedical A Coruña (INIBIC), Hospital A Coruña (CHUAC), University of A Coruña (UDC), A Coruña, Spain
- Study Group on Mechanisms of Action and Resistance to Antimicrobials (GEMARA), Spanish Society of Infectious Diseases and Clinical Microbiology (SEIMC), Madrid
| | - Olga Pacios
- Microbiology Department, Research Institute Biomedical A Coruña (INIBIC), Hospital A Coruña (CHUAC), University of A Coruña (UDC), A Coruña, Spain
- Study Group on Mechanisms of Action and Resistance to Antimicrobials (GEMARA), Spanish Society of Infectious Diseases and Clinical Microbiology (SEIMC), Madrid
| | - Elena Perez-Nadales
- Spanish Network for the Research in Infectious Diseases, REIPI, Seville, Spain
- Microbiology Unit, Maimonides Biomedical Research Institute of Cordoba (IMIBIC), University Hospital Reina Sofía, University of Córdoba, Cordoba, Spain
| | - Julian Torre-Cisneros
- Spanish Network for the Research in Infectious Diseases, REIPI, Seville, Spain
- Microbiology Unit, Maimonides Biomedical Research Institute of Cordoba (IMIBIC), University Hospital Reina Sofía, University of Córdoba, Cordoba, Spain
| | - Jesús Oteo-Iglesias
- Study Group on Mechanisms of Action and Resistance to Antimicrobials (GEMARA), Spanish Society of Infectious Diseases and Clinical Microbiology (SEIMC), Madrid
- Spanish Network for the Research in Infectious Diseases, REIPI, Seville, Spain
- Reference and Research Laboratory for Antibiotic Resistance and Health Care Infections, National Centre for Microbiology, Institute of Health Carlos III, Majadahonda, Madrid, Spain
| | - Ferran Navarro
- Study Group on Mechanisms of Action and Resistance to Antimicrobials (GEMARA), Spanish Society of Infectious Diseases and Clinical Microbiology (SEIMC), Madrid
- Microbiology Department, Sant Pau Hospital, Autonomous University of Barcelona (Bellaterra), Barcelona, Spain
| | - Elisenda Miró
- Study Group on Mechanisms of Action and Resistance to Antimicrobials (GEMARA), Spanish Society of Infectious Diseases and Clinical Microbiology (SEIMC), Madrid
- Microbiology Department, Sant Pau Hospital, Autonomous University of Barcelona (Bellaterra), Barcelona, Spain
| | - Alvaro Pascual
- Study Group on Mechanisms of Action and Resistance to Antimicrobials (GEMARA), Spanish Society of Infectious Diseases and Clinical Microbiology (SEIMC), Madrid
- Clinical Unit for Infectious Diseases, Microbiology and Preventive Medicine, Hospital Universitario Virgen Macarena. Deparment of Microbiology and Medicine, University of Seville, Seville, Spain
- Spanish Network for the Research in Infectious Diseases, REIPI, Seville, Spain
| | - German Bou
- Microbiology Department, Research Institute Biomedical A Coruña (INIBIC), Hospital A Coruña (CHUAC), University of A Coruña (UDC), A Coruña, Spain
- Study Group on Mechanisms of Action and Resistance to Antimicrobials (GEMARA), Spanish Society of Infectious Diseases and Clinical Microbiology (SEIMC), Madrid
- Spanish Network for the Research in Infectious Diseases, REIPI, Seville, Spain
| | - Luis Martínez-Martínez
- Study Group on Mechanisms of Action and Resistance to Antimicrobials (GEMARA), Spanish Society of Infectious Diseases and Clinical Microbiology (SEIMC), Madrid
- Spanish Network for the Research in Infectious Diseases, REIPI, Seville, Spain
- Microbiology Unit, Maimonides Biomedical Research Institute of Cordoba (IMIBIC), University Hospital Reina Sofía, University of Córdoba, Cordoba, Spain
| | - Maria Tomas
- Microbiology Department, Research Institute Biomedical A Coruña (INIBIC), Hospital A Coruña (CHUAC), University of A Coruña (UDC), A Coruña, Spain
- Study Group on Mechanisms of Action and Resistance to Antimicrobials (GEMARA), Spanish Society of Infectious Diseases and Clinical Microbiology (SEIMC), Madrid
- Spanish Network for the Research in Infectious Diseases, REIPI, Seville, Spain
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16
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Darbari VC, Ciccone J, Patel JS, Islam B, Agarwal PK, Haider S. Electrostatic Switching Controls Channel Dynamics of the Sensor Protein VirB10 in A. tumefaciens Type IV Secretion System. ACS OMEGA 2020; 5:3271-3281. [PMID: 32118142 PMCID: PMC7045316 DOI: 10.1021/acsomega.9b03313] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Accepted: 01/20/2020] [Indexed: 05/19/2023]
Abstract
Type IV secretion systems are large nanomachines assembled across the bacterial cell envelope for effector translocation and conjugation. VirB10 traverses the inner and outer membranes, sensing cellular signals for coordinating the conformational switch for pilus biogenesis and/or secretion. Mutations uncoupling secretion from pilus biogenesis were identified in Agrobacterium tumefaciens VirB10 including a gating defect mutation G272R that made VirB10 unresponsive to intracellular ATP, causing unregulated secretion of VirE2 in a contact-independent manner. Comparative long-timescale molecular dynamics of the wild type and G272R mutant of the A. tumefaciens VirB10CTD tetradecamer reveals how the G272R mutation locks the oligomer in a rigid conformation by swapping the ionic interactions between the loops from the β-barrel close to the inner leaflet of the outer membrane. This electrostatic switching changes the allosteric communication pathway from the extracellular loop to the base of the barrel, suggesting that the local conformational dynamics in the loops can gate information across VirB10.
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Affiliation(s)
- Vidya Chandran Darbari
- School
of Biological and Chemical Sciences, Queen
Mary University of London, Mile End Road, London E1 4NS, United Kingdom
- E-mail: . Tel: +44 (0)
20 7882 6360 (V.C.D.)
| | - Jonah Ciccone
- Department
of Pharmaceutical and Biological Chemistry, University College London School of Pharmacy, WC1N 1AX London, United Kingdom
| | - Jagdish Suresh Patel
- Department
of Biological Sciences, University of Idaho, C/O IRIC 333, 875 Perimeter MS 1122, Moscow, Idaho 83844-1122, United States
| | - Barira Islam
- Centre
for Biomarker Research, School of Applied Sciences, University of Huddersfield, HD1 3DH Huddersfield, United Kingdom
| | - Pratul K Agarwal
- Department
of Biochemistry & Cellular and Molecular Biology Department, University of Tennessee-Knoxville, Knoxville, Tennessee 37996, United States
| | - Shozeb Haider
- Department
of Pharmaceutical and Biological Chemistry, University College London School of Pharmacy, WC1N 1AX London, United Kingdom
- E-mail: . Tel: +44 (0) 20 7753 5883 (S.H.)
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17
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Sgro GG, Oka GU, Souza DP, Cenens W, Bayer-Santos E, Matsuyama BY, Bueno NF, dos Santos TR, Alvarez-Martinez CE, Salinas RK, Farah CS. Bacteria-Killing Type IV Secretion Systems. Front Microbiol 2019; 10:1078. [PMID: 31164878 PMCID: PMC6536674 DOI: 10.3389/fmicb.2019.01078] [Citation(s) in RCA: 86] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Accepted: 04/29/2019] [Indexed: 01/25/2023] Open
Abstract
Bacteria have been constantly competing for nutrients and space for billions of years. During this time, they have evolved many different molecular mechanisms by which to secrete proteinaceous effectors in order to manipulate and often kill rival bacterial and eukaryotic cells. These processes often employ large multimeric transmembrane nanomachines that have been classified as types I-IX secretion systems. One of the most evolutionarily versatile are the Type IV secretion systems (T4SSs), which have been shown to be able to secrete macromolecules directly into both eukaryotic and prokaryotic cells. Until recently, examples of T4SS-mediated macromolecule transfer from one bacterium to another was restricted to protein-DNA complexes during bacterial conjugation. This view changed when it was shown by our group that many Xanthomonas species carry a T4SS that is specialized to transfer toxic bacterial effectors into rival bacterial cells, resulting in cell death. This review will focus on this special subtype of T4SS by describing its distinguishing features, similar systems in other proteobacterial genomes, and the nature of the effectors secreted by these systems and their cognate inhibitors.
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Affiliation(s)
- Germán G. Sgro
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
| | - Gabriel U. Oka
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
| | - Diorge P. Souza
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
| | - William Cenens
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
| | - Ethel Bayer-Santos
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
| | - Bruno Y. Matsuyama
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
| | - Natalia F. Bueno
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
| | | | - Cristina E. Alvarez-Martinez
- Departamento de Genética, Evolução, Microbiologia e Imunologia, Instituto de Biologia, University of Campinas (UNICAMP), Campinas, Brazil
| | - Roberto K. Salinas
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
| | - Chuck S. Farah
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
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18
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Abstract
Helicobacter pylori colonizes about half of humans worldwide, and its presence in the gastric mucosa is associated with an increased risk of gastric adenocarcinoma, gastric lymphoma, and peptic ulcer disease. H. pylori strains carrying the cag pathogenicity island (cagPAI) are associated with increased risk of disease progression. The cagPAI encodes the Cag type IV secretion system (CagT4SS), which delivers the CagA oncoprotein and other effector molecules into human gastric epithelial cells. We visualized structures of native and mutant CagT4SS machines on the H. pylori cell envelope by cryoelectron tomography. Individual H. pylori cells contain multiple CagT4SS nanomachines, each composed of a wheel-shaped outer membrane complex (OMC) with 14-fold symmetry and an inner membrane complex (IMC) with 6-fold symmetry. CagX, CagY, and CagM are required for assembly of the OMC, whereas strains lacking Cag3 and CagT produce outer membrane complexes lacking peripheral components. The IMC, which has never been visualized in detail, is configured as six tiers in cross-section view and three concentric rings surrounding a central channel in end-on view. The IMC contains three T4SS ATPases: (i) VirB4-like CagE, arranged as a hexamer of dimers at the channel entrance; (ii) a hexamer of VirB11-like Cagα, docked at the base of the CagE hexamer; and (iii) VirD4-like Cagβ and other unspecified Cag subunits, associated with the stacked CagE/Cagα complex and forming the outermost rings. The CagT4SS and recently solved Legionella pneumophila Dot/Icm system comprise new structural prototypes for the T4SS superfamily.IMPORTANCE Bacterial type IV secretion systems (T4SSs) have been phylogenetically grouped into two subfamilies. The T4ASSs, represented by the Agrobacterium tumefaciens VirB/VirD4T4SS, include "minimized" machines assembled from 12 VirB- and VirD4-like subunits and compositionally larger systems such as the Helicobacter pylori CagT4SS T4BSSs encompass systems closely related in subunit composition to the Legionella pneumophila Dot/IcmT4SS Here, we present structures of native and mutant H. pylori Cag machines determined by in situ cryoelectron tomography. We identify distinct outer and inner membrane complexes and, for the first time, visualize structural contributions of all three "signature" ATPases of T4SSs at the cytoplasmic entrance of the translocation channel. Despite their evolutionary divergence, the CagT4SS aligns structurally much more closely to the Dot/IcmT4SS than an available VirB/VirD4 subcomplex. Our findings highlight the diversity of T4SSs and suggest a structural classification scheme in which T4SSs are grouped as minimized VirB/VirD4-like or larger Cag-like and Dot/Icm-like systems.
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19
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Boudaher E, Shaffer CL. Inhibiting bacterial secretion systems in the fight against antibiotic resistance. MEDCHEMCOMM 2019; 10:682-692. [PMID: 31741728 PMCID: PMC6677025 DOI: 10.1039/c9md00076c] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Accepted: 04/22/2019] [Indexed: 12/11/2022]
Abstract
Antimicrobial resistance is a mounting global health crisis that threatens a resurgence of life-threatening bacterial infections. Despite intensive drug discovery efforts, the rate of antimicrobial resistance outpaces the discovery of new antibiotic agents. One of the major mechanisms driving the rapid propagation of antibiotic resistance is bacterial conjugation mediated by the versatile type IV secretion system (T4SS). The search for therapeutic compounds that prevent the spread of antibiotic resistance via T4SS-dependent mechanisms has identified several promising molecular scaffolds that disrupt resistance determinant dissemination. In this brief review, we highlight the progress and potential of conjugation inhibitors and anti-virulence compounds that target diverse T4SS machineries. These studies provide a solid foundation for the future development of potent, dual-purpose molecular scaffolds that can be used as biochemical tools to probe type IV secretion mechanisms and target bacterial conjugation in clinical settings to prevent the dissemination of antibiotic resistance throughout microbial populations.
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Affiliation(s)
- Elizabeth Boudaher
- University of Kentucky , Department of Veterinary Science , Gluck Equine Research Center , 1400 Nicholasville Road , Lexington , KY , USA . ; Tel: +1 (859) 218 1168
| | - Carrie L Shaffer
- University of Kentucky , Department of Veterinary Science , Gluck Equine Research Center , 1400 Nicholasville Road , Lexington , KY , USA . ; Tel: +1 (859) 218 1168
- University of Kentucky , Department of Microbiology, Immunology, and Molecular Genetics , 800 Rose Street , Lexington , KY , USA
- University of Kentucky , Department of Pharmaceutical Sciences , 789 South Limestone Street , Lexington , KY , USA
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20
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Abstract
Type IV secretion systems (T4SSs) are nanomachines that Gram-negative, Gram-positive bacteria, and some archaea use to transport macromolecules across their membranes into bacterial or eukaryotic host targets or into the extracellular milieu. They are the most versatile secretion systems, being able to deliver both proteins and nucleoprotein complexes into targeted cells. By mediating conjugation and/or competence, T4SSs play important roles in determining bacterial genome plasticity and diversity; they also play a pivotal role in the spread of antibiotic resistance within bacterial populations. T4SSs are also used by human pathogens such as Legionella pneumophila, Bordetella pertussis, Brucella sp., or Helicobacter pylori to sustain infection. Since they are essential virulence factors for these important pathogens, T4SSs might represent attractive targets for vaccines and therapeutics. The best-characterized conjugative T4SSs of Gram-negative bacteria are composed of twelve components that are conserved across many T4SSs. In this chapter, we will review our current structural knowledge on the T4SSs by describing the structures of the individual components and how they assemble into large macromolecular assemblies. With the combined efforts of X-ray crystallography, nuclear magnetic resonance (NMR), and more recently electron microscopy, structural biology of the T4SS has made spectacular progress during the past fifteen years and has unraveled the properties of unique proteins and complexes that assemble dynamically in a highly sophisticated manner.
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21
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Ghosal D, Jeong KC, Chang YW, Gyore J, Teng L, Gardner A, Vogel JP, Jensen GJ. Molecular architecture, polar targeting and biogenesis of the Legionella Dot/Icm T4SS. Nat Microbiol 2019; 4:1173-1182. [PMID: 31011165 PMCID: PMC6588468 DOI: 10.1038/s41564-019-0427-4] [Citation(s) in RCA: 64] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 03/12/2019] [Indexed: 01/10/2023]
Abstract
Legionella pneumophila survives and replicates inside host cells by secreting ~300 effectors through the Dot/Icm type IVB secretion system (T4BSS). Here, we used complementary electron cryotomography (ECT) and immunofluorescence microscopy (IF) to investigate the molecular architecture and biogenesis of the Dot/Icm secretion apparatus. ECT mapped the location of the core and accessory components of the Legionella core-transmembrane subcomplex revealing a well-ordered central channel that opens into a large, windowed secretion chamber with an unusual 13-fold symmetry. IF deciphered an early-stage assembly process that begins with targeting of Dot/Icm components to the bacterial poles. Polar targeting of this T4BSS is mediated by two Dot/Icm proteins, DotU and IcmF, that interestingly are homologs of the T6SS membrane complex components TssL and TssM, suggesting the Dot/Icm T4BSS is a hybrid system. Together these results revealed that the Dot/Icm complex assembles in an “axial-to-peripheral” pattern.
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Affiliation(s)
- Debnath Ghosal
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Kwangcheol C Jeong
- Department of Molecular Microbiology, Washington University School of Medicine, St Louis, MO, USA.,Department of Animal Sciences & Emerging Pathogens Institute, University of Florida, Gainesville, FL, USA
| | - Yi-Wei Chang
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA.,Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Jacob Gyore
- Department of Molecular Microbiology, Washington University School of Medicine, St Louis, MO, USA
| | - Lin Teng
- Department of Animal Sciences & Emerging Pathogens Institute, University of Florida, Gainesville, FL, USA
| | - Adam Gardner
- Molecular Graphics Laboratory, Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA, USA
| | - Joseph P Vogel
- Department of Molecular Microbiology, Washington University School of Medicine, St Louis, MO, USA.
| | - Grant J Jensen
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA, USA. .,Howard Hughes Medical Institute, California Institute of Technology, Pasadena, CA, USA.
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22
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Spread and Persistence of Virulence and Antibiotic Resistance Genes: A Ride on the F Plasmid Conjugation Module. EcoSal Plus 2019; 8. [PMID: 30022749 DOI: 10.1128/ecosalplus.esp-0003-2018] [Citation(s) in RCA: 55] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The F plasmid or F-factor is a large, 100-kbp, circular conjugative plasmid of Escherichia coli and was originally described as a vector for horizontal gene transfer and gene recombination in the late 1940s. Since then, F and related F-like plasmids have served as role models for bacterial conjugation. At present, more than 200 different F-like plasmids with highly related DNA transfer genes, including those for the assembly of a type IV secretion apparatus, are completely sequenced. They belong to the phylogenetically related MOBF12A group. F-like plasmids are present in enterobacterial hosts isolated from clinical as well as environmental samples all over the world. As conjugative plasmids, F-like plasmids carry genetic modules enabling plasmid replication, stable maintenance, and DNA transfer. In this plasmid backbone of approximately 60 kbp, the DNA transfer genes occupy the largest and mostly conserved part. Subgroups of MOBF12A plasmids can be defined based on the similarity of TraJ, a protein required for DNA transfer gene expression. In addition, F-like plasmids harbor accessory cargo genes, frequently embedded within transposons and/or integrons, which harness their host bacteria with antibiotic resistance and virulence genes, causing increasingly severe problems for the treatment of infectious diseases. Here, I focus on key genetic elements and their encoded proteins present on the F-factor and other typical F-like plasmids belonging to the MOBF12A group of conjugative plasmids.
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23
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Abstract
Many bacteria have evolved specialized nanomachines with the remarkable ability to inject multiple bacterially encoded effector proteins into eukaryotic or prokaryotic cells. Known as type III, type IV, and type VI secretion systems, these machines play a central role in the pathogenic or symbiotic interactions between multiple bacteria and their eukaryotic hosts, or in the establishment of bacterial communities in a diversity of environments. Here we focus on recent progress elucidating the structure and assembly pathways of these machines. As many of the interactions shaped by these machines are of medical importance, they provide an opportunity to develop novel therapeutic approaches to combat important human diseases.
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Affiliation(s)
- Jorge E Galán
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, CT 06536, USA.
| | - Gabriel Waksman
- Institute of Structural and Molecular Biology, Birkbeck, Malet Street, London WC1E 7HX, UK; Institute of Structural and Molecular Biology, University College London, Gower Street, London WC1E 6BT, UK.
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24
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Waksman G. From conjugation to T4S systems in Gram-negative bacteria: a mechanistic biology perspective. EMBO Rep 2019; 20:embr.201847012. [PMID: 30602585 PMCID: PMC6362355 DOI: 10.15252/embr.201847012] [Citation(s) in RCA: 103] [Impact Index Per Article: 20.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 10/31/2018] [Accepted: 11/27/2018] [Indexed: 12/19/2022] Open
Abstract
Conjugation is the process by which bacteria exchange genetic materials in a unidirectional manner from a donor cell to a recipient cell. The discovery of conjugation signalled the dawn of genetics and molecular biology. In Gram-negative bacteria, the process of conjugation is mediated by a large membrane-embedded machinery termed "conjugative type IV secretion (T4S) system", a large injection nanomachine, which together with a DNA-processing machinery termed "the relaxosome" and a large extracellular tube termed "pilus" orchestrates directional DNA transfer. Here, the focus is on past and latest research in the field of conjugation and T4S systems in Gram-negative bacteria, with an emphasis on the various questions and debates that permeate the field from a mechanistic perspective.
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Affiliation(s)
- Gabriel Waksman
- Institute of Structural and Molecular Biology, UCL and Birkbeck, London, UK
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25
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Abstract
To interact with the external environments, bacteria often display long proteinaceous appendages on their cell surface, called pili or fimbriae. These non-flagellar thread-like structures are polymers composed of covalently or non-covalently interacting repeated pilin subunits. Distinct pilus classes can be identified on basis of their assembly pathways, including chaperone-usher pili, type V pili, type IV pili, curli and fap fibers, conjugative and type IV secretion pili, as well as sortase-mediated pili. Pili play versatile roles in bacterial physiology, and can be involved in adhesion and host cell invasion, DNA and protein secretion and uptake, biofilm formation, cell motility and more. Recent advances in structure determination of components involved in the various pilus systems has enabled a better molecular understanding of their mechanisms of assembly and function. In this chapter we describe the diversity in structure, biogenesis and function of the different pilus systems found in Gram-positive and Gram-negative bacteria, and review their potential as anti-microbial targets.
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Affiliation(s)
- Magdalena Lukaszczyk
- Structural Biology Brussels, Vrije Universiteit Brussel, Pleinlaan 2, 1050, Brussels, Belgium
- Structural and Molecular Microbiology, Structural Biology Research Center, VIB, Pleinlaan 2, 1050, Brussels, Belgium
| | - Brajabandhu Pradhan
- Structural Biology Brussels, Vrije Universiteit Brussel, Pleinlaan 2, 1050, Brussels, Belgium
- Structural and Molecular Microbiology, Structural Biology Research Center, VIB, Pleinlaan 2, 1050, Brussels, Belgium
| | - Han Remaut
- Structural Biology Brussels, Vrije Universiteit Brussel, Pleinlaan 2, 1050, Brussels, Belgium.
- Structural and Molecular Microbiology, Structural Biology Research Center, VIB, Pleinlaan 2, 1050, Brussels, Belgium.
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26
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Sgro GG, Costa TRD, Cenens W, Souza DP, Cassago A, Coutinho de Oliveira L, Salinas RK, Portugal RV, Farah CS, Waksman G. Cryo-EM structure of the bacteria-killing type IV secretion system core complex from Xanthomonas citri. Nat Microbiol 2018; 3:1429-1440. [PMID: 30349081 PMCID: PMC6264810 DOI: 10.1038/s41564-018-0262-z] [Citation(s) in RCA: 53] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2018] [Accepted: 09/03/2018] [Indexed: 12/17/2022]
Abstract
Type IV secretion (T4S) systems form the most common and versatile class of secretion systems in bacteria, capable of injecting both proteins and DNAs into host cells. T4S systems are typically composed of 12 components that form two major assemblies: the inner membrane complex embedded in the inner membrane and the core complex embedded in both the inner and outer membranes. Here we present the 3.3 Å resolution cryo-electron microscopy model of the T4S system core complex from Xanthomonas citri, a phytopathogen that utilizes this system to kill bacterial competitors. An extensive mutational investigation was performed to probe the vast network of protein-protein interactions in this 1.13 MDa assembly. This structure expands our knowledge of the molecular details of T4S system organization, assembly and evolution.
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Affiliation(s)
- Germán G Sgro
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil.,Institute of Structural and Molecular Biology at UCL and Birkbeck College, Department of Biological Sciences, Birkbeck College, London, UK
| | - Tiago R D Costa
- Institute of Structural and Molecular Biology at UCL and Birkbeck College, Department of Biological Sciences, Birkbeck College, London, UK.,MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London, UK
| | - William Cenens
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
| | - Diorge P Souza
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil.,MRC Laboratory for Molecular Cell Biology, University College London, London, UK
| | - Alexandre Cassago
- Laboratório Nacional de Nanotecnologia (LNNano), Centro Nacional de Pesquisa em Energia e Materiais (CNPEM), Campinas, Brazil
| | - Luciana Coutinho de Oliveira
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil.,Department of Medicinal Chemistry, Université du Québec, INRS - Institut Armand-Frappier, Laval, Québec, Canada
| | - Roberto K Salinas
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
| | - Rodrigo V Portugal
- Laboratório Nacional de Nanotecnologia (LNNano), Centro Nacional de Pesquisa em Energia e Materiais (CNPEM), Campinas, Brazil
| | - Chuck S Farah
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil.
| | - Gabriel Waksman
- Institute of Structural and Molecular Biology at UCL and Birkbeck College, Department of Biological Sciences, Birkbeck College, London, UK. .,Institute of Structural and Molecular Biology at UCL and Birkbeck College, Research Department of Structural and Molecular Biology, Division of Biosciences, University College London, London, UK.
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27
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Kooger R, Szwedziak P, Böck D, Pilhofer M. CryoEM of bacterial secretion systems. Curr Opin Struct Biol 2018; 52:64-70. [PMID: 30223223 DOI: 10.1016/j.sbi.2018.08.007] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Revised: 05/18/2018] [Accepted: 08/29/2018] [Indexed: 02/06/2023]
Abstract
The need for bacteria to interact with their environment has driven the evolution of elaborate secretion systems. By virtue of their function, secretion systems are macromolecular complexes associated with the cell envelope and therefore inherently difficult to study by conventional structural biology techniques. Cryo-electron microscopy (cryoEM) has become an invaluable technique to study large membrane-embedded complexes and led to major advances in the mechanistic understanding of secretion systems. CryoEM comprises of two main modalities, namely single particle analysis and tomography. Here, we review how detailed structures retrieved by single particle analysis combine elegantly with tomography experiments in which the secretion systems are observed in their native cellular context.
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Affiliation(s)
- Romain Kooger
- Institute of Molecular Biology & Biophysics, Eidgenössische Technische Hochschule Zürich, CH-8093 Zürich, Switzerland
| | - Piotr Szwedziak
- Institute of Molecular Biology & Biophysics, Eidgenössische Technische Hochschule Zürich, CH-8093 Zürich, Switzerland
| | - Désirée Böck
- Institute of Molecular Biology & Biophysics, Eidgenössische Technische Hochschule Zürich, CH-8093 Zürich, Switzerland
| | - Martin Pilhofer
- Institute of Molecular Biology & Biophysics, Eidgenössische Technische Hochschule Zürich, CH-8093 Zürich, Switzerland.
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28
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Rapisarda C, Tassinari M, Gubellini F, Fronzes R. Using Cryo-EM to Investigate Bacterial Secretion Systems. Annu Rev Microbiol 2018; 72:231-254. [PMID: 30004822 DOI: 10.1146/annurev-micro-090817-062702] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Bacterial secretion systems are responsible for releasing macromolecules to the extracellular milieu or directly into other cells. These membrane complexes are associated with pathogenicity and bacterial fitness. Understanding of these large assemblies has exponentially increased in the last few years thanks to electron microscopy. In fact, a revolution in this field has led to breakthroughs in characterizing the structures of secretion systems and other macromolecular machineries so as to obtain high-resolution images of complexes that could not be crystallized. In this review, we give a brief overview of structural advancements in the understanding of secretion systems, focusing in particular on cryo-electron microscopy, whether tomography or single-particle analysis. We describe how such techniques have contributed to knowledge of the mechanism of macromolecule secretion in bacteria and the impact they will have in the future.
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Affiliation(s)
- Chiara Rapisarda
- Structure et Fonction des Nanomachines Bactériennes, Institut Européen de Chimie et Biologie, 33607 Pessac, France; , .,CNRS UMR5234, Université de Bordeaux, 33076 Bordeaux, France
| | - Matteo Tassinari
- Institut Pasteur, Unité de Microbiologie Structurale, 75724 Paris, France; .,CNRS UMR3528, Institut Pasteur, 75015 Paris, France
| | - Francesca Gubellini
- Institut Pasteur, Unité de Microbiologie Structurale, 75724 Paris, France; .,CNRS UMR3528, Institut Pasteur, 75015 Paris, France
| | - Rémi Fronzes
- Structure et Fonction des Nanomachines Bactériennes, Institut Européen de Chimie et Biologie, 33607 Pessac, France; , .,CNRS UMR5234, Université de Bordeaux, 33076 Bordeaux, France
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29
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Abstract
Structural studies of biocomplexes using single-particle cryo-electron microscopy (cryo-EM) is now a well-established technique in structural biology and has become competitive with X-ray crystallography. The latest advances in EM enable us to determine structures of protein complexes at 3-5 Å resolution for an extremely broad range of sizes from ~200 kDa up to hundreds of megadaltons (Bartesaghi et al., Science 348(6239):1147-1151, 2051; Bai et al., Nature 525(7568):212-217, 2015; Vinothkumar et al., Nature 515(7525):80-84, 2014; Grigorieff and Harrison, Curr Opin Struct Biol 21(2):265-273, 2011). The majority of biocomplexes comprise a number of different components and are not amenable to crystallisation. Secretion systems are typical examples of such multi-protein complexes, and structural studies of them are extremely challenging. The only feasible approach to revealing their spatial organisation and functional modification is cryo-EM. The development of systems for digital registration of images and algorithms for the fast and efficient processing of recorded images and subsequent analysis facilitated the determination of structures at near-atomic resolution. In this review we will describe sample preparation for cryo-EM, how data are collected by new detectors, and the logistics of image analysis through the basic steps required for reconstructions of both small and large biological complexes and their refinement to nearly atomic resolution. The processing workflow is illustrated using examples of EM analysis of a Type IV Secretion System.
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30
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Bats SH, Bergé C, Coombs N, Terradot L, Josenhans C. Biochemical characterization of the Helicobacter pylori Cag Type 4 Secretion System protein CagN and its interaction partner CagM. Int J Med Microbiol 2018; 308:425-437. [PMID: 29572102 DOI: 10.1016/j.ijmm.2018.02.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2018] [Revised: 02/22/2018] [Accepted: 02/25/2018] [Indexed: 12/26/2022] Open
Abstract
Highly virulent Helicobacter pylori strains contain the cag pathogenicity island (cagPAI). It codes for about 30 proteins forming a type IV secretion system (T4SS) which translocates the pro-inflammatory protein CagA into epithelial host cells. While CagA and various other Cag proteins have been extensively studied, several cagPAI proteins are poorly characterized or of unknown function. CagN (HP0538) is of unknown function but highly conserved in the cagPAI suggesting an important role. cagM (HP0537) is the first gene of the cagMN operon and its product is part of the CagT4SS core complex. Both proteins do not have detectable homologs in other type IV secretion systems. We have characterized the biochemical and structural properties of CagN and CagM and their interaction. We demonstrate by circular dichroism, Multi-Angle Light Scattering (MALS) and small angle X-ray scattering (SAXS) that CagN is a folded, predominantly monomeric protein with an elongated shape in solution. CagM is folded and forms predominantly dimers that are also elongated in solution. We found by various in vivo and in vitro methods that CagN and CagM directly interact with each other. CagM self-interacts stably with a low nanomolar KD and can form stable multimers. Finally, in vivo experiments show that deletion of CagM reduces the amounts of CagN and other outer CagPAI proteins in H. pylori cells.
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Affiliation(s)
- Simon H Bats
- Institut für Medizinische Mikrobiologie und Krankenhaushygiene, Medizinische Hochschule Hannover, Carl-Neuberg-Straße 1, 30625 Hannover, Germany; Max von Pettenkofer Institute, Ludwig Maximilians Universität LMU München, Pettenkoferstraße 9a, 80336 München, Germany
| | - Célia Bergé
- UMR 5086 Molecular Microbiology and Structural Biochemistry CNRS-Université de Lyon 1, Institut de Biologie et Chimie des Protéines, 7 Passage du Vercors, 69367 Lyon, Cedex 07, France
| | - Nina Coombs
- Institut für Medizinische Mikrobiologie und Krankenhaushygiene, Medizinische Hochschule Hannover, Carl-Neuberg-Straße 1, 30625 Hannover, Germany; German Center for Infection Research (DZIF), Partner Site Hannover-Braunschweig, Germany; German Center for Infection Research (DZIF), Partner Site Munich, Germany
| | - Laurent Terradot
- UMR 5086 Molecular Microbiology and Structural Biochemistry CNRS-Université de Lyon 1, Institut de Biologie et Chimie des Protéines, 7 Passage du Vercors, 69367 Lyon, Cedex 07, France
| | - Christine Josenhans
- Institut für Medizinische Mikrobiologie und Krankenhaushygiene, Medizinische Hochschule Hannover, Carl-Neuberg-Straße 1, 30625 Hannover, Germany; Max von Pettenkofer Institute, Ludwig Maximilians Universität LMU München, Pettenkoferstraße 9a, 80336 München, Germany; German Center for Infection Research (DZIF), Partner Site Hannover-Braunschweig, Germany; German Center for Infection Research (DZIF), Partner Site Munich, Germany.
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31
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Grohmann E, Christie PJ, Waksman G, Backert S. Type IV secretion in Gram-negative and Gram-positive bacteria. Mol Microbiol 2018; 107:455-471. [PMID: 29235173 PMCID: PMC5796862 DOI: 10.1111/mmi.13896] [Citation(s) in RCA: 224] [Impact Index Per Article: 37.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Revised: 12/07/2017] [Accepted: 12/09/2017] [Indexed: 02/06/2023]
Abstract
Type IV secretion systems (T4SSs) are versatile multiprotein nanomachines spanning the entire cell envelope in Gram-negative and Gram-positive bacteria. They play important roles through the contact-dependent secretion of effector molecules into eukaryotic hosts and conjugative transfer of mobile DNA elements as well as contact-independent exchange of DNA with the extracellular milieu. In the last few years, many details on the molecular mechanisms of T4SSs have been elucidated. Exciting structures of T4SS complexes from Escherichia coli plasmids R388 and pKM101, Helicobacter pylori and Legionella pneumophila have been solved. The structure of the F-pilus was also reported and surprisingly revealed a filament composed of pilin subunits in 1:1 stoichiometry with phospholipid molecules. Many new T4SSs have been identified and characterized, underscoring the structural and functional diversity of this secretion superfamily. Complex regulatory circuits also have been shown to control T4SS machine production in response to host cell physiological status or a quorum of bacterial recipient cells in the vicinity. Here, we summarize recent advances in our knowledge of 'paradigmatic' and emerging systems, and further explore how new basic insights are aiding in the design of strategies aimed at suppressing T4SS functions in bacterial infections and spread of antimicrobial resistances.
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Affiliation(s)
- Elisabeth Grohmann
- Beuth University of Applied Sciences Berlin, Life Sciences and Technology, D-13347 Berlin, Germany
| | - Peter J. Christie
- Department of Microbiology and Molecular Genetics, The University of Texas Medical School at Houston, 6431 Fannin St, Houston, Texas 77030, USA
| | - Gabriel Waksman
- Institute of Structural and Molecular Biology, University College London and Birkbeck College, London WC1E 7HX, United Kingdom
| | - Steffen Backert
- Friedrich Alexander University Erlangen-Nuremberg, Department of Biology, Division of Microbiology, Staudtstrasse 5, D-91058 Erlangen, Germany
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32
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Koelblen T, Bergé C, Cherrier MV, Brillet K, Jimenez-Soto L, Ballut L, Takagi J, Montserret R, Rousselle P, Fischer W, Haas R, Fronzes R, Terradot L. Molecular dissection of protein-protein interactions between integrin α5β1 and the Helicobacter pylori
Cag type IV secretion system. FEBS J 2017; 284:4143-4157. [DOI: 10.1111/febs.14299] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2017] [Revised: 10/04/2017] [Accepted: 10/17/2017] [Indexed: 12/31/2022]
Affiliation(s)
- Thomas Koelblen
- UMR 5086 Molecular Microbiology and Structural Biochemistry; Institut de Biologie et Chimie des Protéines; CNRS-Université de Lyon; France
| | - Célia Bergé
- UMR 5086 Molecular Microbiology and Structural Biochemistry; Institut de Biologie et Chimie des Protéines; CNRS-Université de Lyon; France
| | - Mickaël V. Cherrier
- UMR 5086 Molecular Microbiology and Structural Biochemistry; Institut de Biologie et Chimie des Protéines; CNRS-Université de Lyon; France
| | - Karl Brillet
- UMR 5086 Molecular Microbiology and Structural Biochemistry; Institut de Biologie et Chimie des Protéines; CNRS-Université de Lyon; France
| | - Luisa Jimenez-Soto
- Max von Pettenkofer-Institut für Hygiene und Medizinische Mikrobiologie; Ludwig-Maximilians-Universität; München Germany
| | - Lionel Ballut
- UMR 5086 Molecular Microbiology and Structural Biochemistry; Institut de Biologie et Chimie des Protéines; CNRS-Université de Lyon; France
| | - Junichi Takagi
- Laboratory of Protein Synthesis and Expression; Institute for Protein Research; Osaka University; Japan
| | - Roland Montserret
- UMR 5086 Molecular Microbiology and Structural Biochemistry; Institut de Biologie et Chimie des Protéines; CNRS-Université de Lyon; France
| | - Patricia Rousselle
- Laboratoire de Biologie Tissulaire et Ingénierie Thérapeutique; UMR 5305; CNRS; University Lyon 1; France
| | - Wolfgang Fischer
- Max von Pettenkofer-Institut für Hygiene und Medizinische Mikrobiologie; Ludwig-Maximilians-Universität; München Germany
| | - Rainer Haas
- Max von Pettenkofer-Institut für Hygiene und Medizinische Mikrobiologie; Ludwig-Maximilians-Universität; München Germany
- German Center for Infection Research (DZIF); Partner Site LMU; München Germany
| | - Rémi Fronzes
- European Institute of Chemistry and Biology; CNRS; UMR 5234; Microbiologie Fondamentale et Pathogénicité; University of Bordeaux; Pessac France
| | - Laurent Terradot
- UMR 5086 Molecular Microbiology and Structural Biochemistry; Institut de Biologie et Chimie des Protéines; CNRS-Université de Lyon; France
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33
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Redzej A, Ukleja M, Connery S, Trokter M, Felisberto-Rodrigues C, Cryar A, Thalassinos K, Hayward RD, Orlova EV, Waksman G. Structure of a VirD4 coupling protein bound to a VirB type IV secretion machinery. EMBO J 2017; 36:3080-3095. [PMID: 28923826 PMCID: PMC5916273 DOI: 10.15252/embj.201796629] [Citation(s) in RCA: 62] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2017] [Revised: 08/09/2017] [Accepted: 08/22/2017] [Indexed: 01/26/2023] Open
Abstract
Type IV secretion (T4S) systems are versatile bacterial secretion systems mediating transport of protein and/or DNA. T4S systems are generally composed of 11 VirB proteins and 1 VirD protein (VirD4). The VirB1‐11 proteins assemble to form a secretion machinery and a pilus while the VirD4 protein is responsible for substrate recruitment. The structure of VirD4 in isolation is known; however, its structure bound to the VirB1‐11 apparatus has not been determined. Here, we purify a T4S system with VirD4 bound, define the biochemical requirements for complex formation and describe the protein–protein interaction network in which VirD4 is involved. We also solve the structure of this complex by negative stain electron microscopy, demonstrating that two copies of VirD4 dimers locate on both sides of the apparatus, in between the VirB4 ATPases. Given the central role of VirD4 in type IV secretion, our study provides mechanistic insights on a process that mediates the dangerous spread of antibiotic resistance genes among bacterial populations.
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Affiliation(s)
- Adam Redzej
- Department of Biological Sciences, Institute of Structural and Molecular Biology, Birkbeck, London, UK
| | - Marta Ukleja
- Department of Biological Sciences, Institute of Structural and Molecular Biology, Birkbeck, London, UK
| | - Sarah Connery
- Department of Biological Sciences, Institute of Structural and Molecular Biology, Birkbeck, London, UK
| | - Martina Trokter
- Department of Biological Sciences, Institute of Structural and Molecular Biology, Birkbeck, London, UK
| | | | - Adam Cryar
- Division of Biosciences, Institute of Structural and Molecular Biology, University College of London, London, UK
| | - Konstantinos Thalassinos
- Department of Biological Sciences, Institute of Structural and Molecular Biology, Birkbeck, London, UK.,Division of Biosciences, Institute of Structural and Molecular Biology, University College of London, London, UK
| | - Richard D Hayward
- Department of Biological Sciences, Institute of Structural and Molecular Biology, Birkbeck, London, UK.,Division of Biosciences, Institute of Structural and Molecular Biology, University College of London, London, UK
| | - Elena V Orlova
- Department of Biological Sciences, Institute of Structural and Molecular Biology, Birkbeck, London, UK
| | - Gabriel Waksman
- Department of Biological Sciences, Institute of Structural and Molecular Biology, Birkbeck, London, UK .,Division of Biosciences, Institute of Structural and Molecular Biology, University College of London, London, UK
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34
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Hepp C, Maier B. Bacterial Translocation Ratchets: Shared Physical Principles with Different Molecular Implementations: How bacterial secretion systems bias Brownian motion for efficient translocation of macromolecules. Bioessays 2017; 39. [PMID: 28895164 DOI: 10.1002/bies.201700099] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2017] [Revised: 08/02/2017] [Indexed: 12/20/2022]
Abstract
Secretion systems enable bacteria to import and secrete large macromolecules including DNA and proteins. While most components of these systems have been identified, the molecular mechanisms of macromolecular transport remain poorly understood. Recent findings suggest that various bacterial secretion systems make use of the translocation ratchet mechanism for transporting polymers across the cell envelope. Translocation ratchets are powered by chemical potential differences generated by concentration gradients of ions or molecules that are specific to the respective secretion systems. Bacteria employ these potential differences for biasing Brownian motion of the macromolecules within the conduits of the secretion systems. Candidates for this mechanism include DNA import by the type II secretion/type IV pilus system, DNA export by the type IV secretion system, and protein export by the type I secretion system. Here, we propose that these three secretion systems employ different molecular implementations of the translocation ratchet mechanism.
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Affiliation(s)
- Christof Hepp
- Department of Physics Universität zu Köln, Köln, Nordrhein-Westfalen, Germany
| | - Berenike Maier
- Department of Physics Universität zu Köln, Köln, Nordrhein-Westfalen, Germany
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35
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Abstract
Pili are crucial virulence factors for many Gram-negative pathogens. These surface structures provide bacteria with a link to their external environments by enabling them to interact with, and attach to, host cells, other surfaces or each other, or by providing a conduit for secretion. Recent high-resolution structures of pilus filaments and the machineries that produce them, namely chaperone-usher pili, type IV pili, conjugative type IV secretion pili and type V pili, are beginning to explain some of the intriguing biological properties that pili exhibit, such as the ability of chaperone-usher pili and type IV pili to stretch in response to external forces. By contrast, conjugative pili provide a conduit for the exchange of genetic information, and recent high-resolution structures have revealed an integral association between the pilin subunit and a phospholipid molecule, which may facilitate DNA transport. In addition, progress in the area of cryo-electron tomography has provided a glimpse of the overall architecture of the type IV pilus machinery. In this Review, we examine recent advances in our structural understanding of various Gram-negative pilus systems and discuss their functional implications.
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36
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Gordon JE, Costa TRD, Patel RS, Gonzalez-Rivera C, Sarkar MK, Orlova EV, Waksman G, Christie PJ. Use of chimeric type IV secretion systems to define contributions of outer membrane subassemblies for contact-dependent translocation. Mol Microbiol 2017; 105:273-293. [PMID: 28452085 DOI: 10.1111/mmi.13700] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/25/2017] [Indexed: 01/26/2023]
Abstract
Recent studies have shown that conjugation systems of Gram-negative bacteria are composed of distinct inner and outer membrane core complexes (IMCs and OMCCs, respectively). Here, we characterized the OMCC by focusing first on a cap domain that forms a channel across the outer membrane. Strikingly, the OMCC caps of the Escherichia coli pKM101 Tra and Agrobacterium tumefaciens VirB/VirD4 systems are completely dispensable for substrate transfer, but required for formation of conjugative pili. The pKM101 OMCC cap and extended pilus also are dispensable for activation of a Pseudomonas aeruginosa type VI secretion system (T6SS). Chimeric conjugation systems composed of the IMCpKM101 joined to OMCCs from the A. tumefaciens VirB/VirD4, E. coli R388 Trw, and Bordetella pertussis Ptl systems support conjugative DNA transfer in E. coli and trigger P. aeruginosa T6SS killing, but not pilus production. The A. tumefaciens VirB/VirD4 OMCC, solved by transmission electron microscopy, adopts a cage structure similar to the pKM101 OMCC. The findings establish that OMCCs are highly structurally and functionally conserved - but also intrinsically conformationally flexible - scaffolds for translocation channels. Furthermore, the OMCC cap and a pilus tip protein coregulate pilus extension but are not required for channel assembly or function.
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Affiliation(s)
- Jay E Gordon
- Department of Microbiology and Molecular Genetics, McGovern Medical School, 6431 Fannin St, Houston, TX, 77030, USA
| | - Tiago R D Costa
- Institute of Structural and Molecular Biology, University College London and Birkbeck, Malet Street, London, WC1E 7HX, UK
| | - Roosheel S Patel
- Department of Microbiology and Molecular Genetics, McGovern Medical School, 6431 Fannin St, Houston, TX, 77030, USA
| | - Christian Gonzalez-Rivera
- Department of Microbiology and Molecular Genetics, McGovern Medical School, 6431 Fannin St, Houston, TX, 77030, USA
| | - Mayukh K Sarkar
- Department of Microbiology and Molecular Genetics, McGovern Medical School, 6431 Fannin St, Houston, TX, 77030, USA
| | - Elena V Orlova
- Institute of Structural and Molecular Biology, University College London and Birkbeck, Malet Street, London, WC1E 7HX, UK
| | - Gabriel Waksman
- Institute of Structural and Molecular Biology, University College London and Birkbeck, Malet Street, London, WC1E 7HX, UK
| | - Peter J Christie
- Department of Microbiology and Molecular Genetics, McGovern Medical School, 6431 Fannin St, Houston, TX, 77030, USA
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37
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Ghosal D, Chang YW, Jeong KC, Vogel JP, Jensen GJ. In situ structure of the Legionella Dot/Icm type IV secretion system by electron cryotomography. EMBO Rep 2017; 18:726-732. [PMID: 28336774 DOI: 10.15252/embr.201643598] [Citation(s) in RCA: 79] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2016] [Revised: 02/15/2017] [Accepted: 02/21/2017] [Indexed: 01/09/2023] Open
Abstract
Type IV secretion systems (T4SSs) are large macromolecular machines that translocate protein and DNA and are involved in the pathogenesis of multiple human diseases. Here, using electron cryotomography (ECT), we report the in situ structure of the Dot/Icm type IVB secretion system (T4BSS) utilized by the human pathogen Legionella pneumophila This is the first structure of a type IVB secretion system, and also the first structure of any T4SS in situ While the Dot/Icm system shares almost no sequence similarity with type IVA secretion systems (T4ASSs), its overall structure is seen here to be remarkably similar to previously reported T4ASS structures (those encoded by the R388 plasmid in Escherichia coli and the cag pathogenicity island in Helicobacter pylori). This structural similarity suggests shared aspects of mechanism. However, compared to the negative-stain reconstruction of the purified T4ASS from the R388 plasmid, the L. pneumophila Dot/Icm system is approximately twice as long and wide and exhibits several additional large densities, reflecting type-specific elaborations and potentially better structural preservation in situ.
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Affiliation(s)
| | - Yi-Wei Chang
- California Institute of Technology, Pasadena, CA, USA
| | | | - Joseph P Vogel
- Washington University School of Medicine, St. Louis, MO, USA
| | - Grant J Jensen
- California Institute of Technology, Pasadena, CA, USA .,Howard Hughes Medical Institute, Pasadena, CA, USA
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38
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Ghazaei C. Molecular Insights into Pathogenesis and Infection with Aspergillus Fumigatus. Malays J Med Sci 2017; 24:10-20. [PMID: 28381925 DOI: 10.21315/mjms2017.24.1.2] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Accepted: 12/13/2016] [Indexed: 01/07/2023] Open
Abstract
The virulence of fungi is dependent on multiple factors, including the immune status of patients and biological features of fungi. In particular, the virulence of Aspergillus fumigatus is due to the complex interaction among various molecules involved in thermotolerance (such as ribosomal biogenesis proteins, α-mannosyltransferase and heat shock proteins), pigment production (DHN-melanin), immune evasion (like melanin and hydrophobin) and nutrient uptake (such as siderophores and zinc transporters). Other molecules also play important roles in the virulence of A. fumigatus, including cell wall components and those which maintain its integrity (for instance β-1-3 glucan, α-1-3 glucan, chitin, galactomannan and mannoproteins) and adhesion (such as hydrophobins), as well as various hydrolytic enzymes (such as serine and aspartic protease, phospholipases, metalloproteinase and dipeptidyl peptidases). Signalling molecules (including G-protein, cAMP, Ras protein and calcineurin) also increase the virulence through altering the metabolic response to stress conditions and toxins (such as gliotoxin, fumitremorgins, fumagatin and helvolic acid).
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Affiliation(s)
- Ciamak Ghazaei
- Department of Microbiology, University of Mohaghegh Ardabili, P.O. Box 179, Ardabil, Iran
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39
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Abstract
Ligand-induced activation of G protein-coupled receptors (GPCRs) is a key mechanism permitting communication between cells and organs. Enormous progress has recently elucidated the structural and dynamic features of GPCR transmembrane signaling. Nanobodies, the recombinant antigen-binding fragments of camelid heavy-chain-only antibodies, have emerged as important research tools to lock GPCRs in particular conformational states. Active-state stabilizing nanobodies have elucidated several agonist-bound structures of hormone-activated GPCRs and have provided insight into the dynamic character of receptors. Nanobodies have also been used to stabilize transient GPCR transmembrane signaling complexes, yielding the first structural insights into GPCR signal transduction across the cellular membrane. Beyond their in vitro uses, nanobodies have served as conformational biosensors in living systems and have provided novel ways to modulate GPCR function. Here, we highlight several examples of how nanobodies have enabled the study of GPCR function and give insights into potential future uses of these important tools.
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Affiliation(s)
- Aashish Manglik
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, California 94305; ,
| | - Brian K Kobilka
- Department of Molecular and Cellular Physiology, Stanford University, Stanford, California 94305; ,
| | - Jan Steyaert
- Structural Biology Brussels, Vrije Universiteit Brussel, 1050 Brussels, Belgium;
- VIB Structural Biology Research Center, Vrije Universiteit Brussel, 1050 Brussels, Belgium
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40
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Erdogan F, Lento C, Yaseen A, Nowroozi-Dayeni R, Kheyson S, Audette GF. Conjugative Mating Assays for Sequence-specific Analysis of Transfer Proteins Involved in Bacterial Conjugation. J Vis Exp 2017. [PMID: 28117821 DOI: 10.3791/54854] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
The transfer of genetic material by bacterial conjugation is a process that takes place via complexes formed by specific transfer proteins. In Escherichia coli, these transfer proteins make up a DNA transfer machinery known as the mating pair formation, or DNA transfer complex, which facilitates conjugative plasmid transfer. The objective of this paper is to provide a method that can be used to determine the role of a specific transfer protein that is involved in conjugation using a series of deletions and/or point mutations in combination with mating assays. The target gene is knocked out on the conjugative plasmid and is then provided in trans through the use of a small recovery plasmid harboring the target gene. Mutations affecting the target gene on the recovery plasmid can reveal information about functional aspects of the target protein that result in the alteration of mating efficiency of donor cells harboring the mutated gene. Alterations in mating efficiency provide insight into the role and importance of the particular transfer protein, or a region therein, in facilitating conjugative DNA transfer. Coupling this mating assay with detailed three-dimensional structural studies will provide a comprehensive understanding of the function of the conjugative transfer protein as well as provide a means for identifying and characterizing regions of protein-protein interaction.
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Affiliation(s)
| | | | | | | | | | - Gerald F Audette
- Department of Chemistry, York University; The Centre for Research on Biomolecular Interactions, York University;
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41
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Costa TRD, Ilangovan A, Ukleja M, Redzej A, Santini JM, Smith TK, Egelman EH, Waksman G. Structure of the Bacterial Sex F Pilus Reveals an Assembly of a Stoichiometric Protein-Phospholipid Complex. Cell 2016; 166:1436-1444.e10. [PMID: 27610568 PMCID: PMC5018250 DOI: 10.1016/j.cell.2016.08.025] [Citation(s) in RCA: 90] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Revised: 07/04/2016] [Accepted: 08/11/2016] [Indexed: 12/05/2022]
Abstract
Conjugative pili are widespread bacterial appendages that play important roles in horizontal gene transfer, in spread of antibiotic resistance genes, and as sites of phage attachment. Among conjugative pili, the F “sex” pilus encoded by the F plasmid is the best functionally characterized, and it is also historically the most important, as the discovery of F-plasmid-mediated conjugation ushered in the era of molecular biology and genetics. Yet, its structure is unknown. Here, we present atomic models of two F family pili, the F and pED208 pili, generated from cryoelectron microscopy reconstructions at 5.0 and 3.6 Å resolution, respectively. These structures reveal that conjugative pili are assemblies of stoichiometric protein-phospholipid units. We further demonstrate that each pilus type binds preferentially to particular phospholipids. These structures provide the molecular basis for F pilus assembly and also shed light on the remarkable properties of conjugative pili in bacterial secretion and phage infection. The atomic structures of the F pilus and an F-like pilus are solved by cryo-EM The structure reveals an assembly of a protein-phospholipid complex unit Mutations at subunit-lipid interfaces affect phage infection and conjugation The structure elucidates the molecular basis for DNA transfer and phage attachment
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Affiliation(s)
- Tiago R D Costa
- Institute of Structural and Molecular Biology, University College London and Birkbeck, Malet Street, London WC1E 7HX, UK
| | - Aravindan Ilangovan
- Institute of Structural and Molecular Biology, University College London and Birkbeck, Malet Street, London WC1E 7HX, UK
| | - Marta Ukleja
- Institute of Structural and Molecular Biology, University College London and Birkbeck, Malet Street, London WC1E 7HX, UK
| | - Adam Redzej
- Institute of Structural and Molecular Biology, University College London and Birkbeck, Malet Street, London WC1E 7HX, UK
| | - Joanne M Santini
- Institute of Structural and Molecular Biology, University College London and Birkbeck, Malet Street, London WC1E 7HX, UK
| | - Terry K Smith
- BSRC, School of Biology, University of St Andrews, St Andrews KY16 9AJ, UK
| | - Edward H Egelman
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA 22908, USA.
| | - Gabriel Waksman
- Institute of Structural and Molecular Biology, University College London and Birkbeck, Malet Street, London WC1E 7HX, UK.
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42
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Oliveira LC, Souza DP, Oka GU, Lima FDS, Oliveira RJ, Favaro DC, Wienk H, Boelens R, Farah CS, Salinas RK. VirB7 and VirB9 Interactions Are Required for the Assembly and Antibacterial Activity of a Type IV Secretion System. Structure 2016; 24:1707-1718. [PMID: 27594685 DOI: 10.1016/j.str.2016.07.015] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2016] [Revised: 07/19/2016] [Accepted: 07/22/2016] [Indexed: 11/16/2022]
Abstract
The type IV secretion system (T4SS) from the phytopathogen Xanthomonas citri (Xac) is a bactericidal nanomachine. The T4SS core complex is a ring composed of multiple copies of VirB7-VirB9-VirB10 subunits. Xac-VirB7 contains a disordered N-terminal tail (VirB7NT) that recognizes VirB9, and a C-terminal domain (VirB7CT) involved in VirB7 self-association. Here, we show that VirB7NT forms a short β strand upon binding to VirB9 and stabilizes it. A tight interaction between them is essential for T4SS assembly and antibacterial activity. Abolishing VirB7 self-association or deletion of the VirB7 C-terminal domain impairs this antibacterial activity without disturbing T4SS assembly. These findings reveal protein interactions within the core complex that are critical for the stability and activity of a T4SS.
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Affiliation(s)
- Luciana Coutinho Oliveira
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, São Paulo 05508-000, Brazil
| | - Diorge Paulo Souza
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, São Paulo 05508-000, Brazil.
| | - Gabriel Umaji Oka
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, São Paulo 05508-000, Brazil
| | - Filipe da Silva Lima
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, São Paulo 05508-000, Brazil
| | - Ronaldo Junio Oliveira
- Departamento de Física, Instituto de Ciências Exatas e Naturais, Universidade Federal do Triângulo Mineiro, Uberaba, Minas Gerais 38064-200, Brazil
| | - Denize Cristina Favaro
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, São Paulo 05508-000, Brazil
| | - Hans Wienk
- NMR Spectroscopy, Bijvoet Center for Biomolecular Research, Utrecht University, Utrecht 3584-CH, the Netherlands
| | - Rolf Boelens
- NMR Spectroscopy, Bijvoet Center for Biomolecular Research, Utrecht University, Utrecht 3584-CH, the Netherlands
| | - Chuck Shaker Farah
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, São Paulo 05508-000, Brazil.
| | - Roberto Kopke Salinas
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, São Paulo 05508-000, Brazil.
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43
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Abstract
AbstractIncreasing evidence suggests that most proteins occur and function in complexes rather than as isolated entities when embedded in cellular membranes. Nuclear magnetic resonance (NMR) provides increasing possibilities to study structure, dynamics and assembly of such systems. In our review, we discuss recent methodological progress to study membrane–protein complexes (MPCs) by NMR, starting with expression, isotope-labeling and reconstitution protocols. We review approaches to deal with spectral complexity and limited spectral spectroscopic sensitivity that are usually encountered in NMR-based studies of MPCs. We highlight NMR applications in various classes of MPCs, including G-protein-coupled receptors, ion channels and retinal proteins and extend our discussion to protein–protein complexes that span entire cellular compartments or orchestrate processes such as protein transport across or within membranes. These examples demonstrate the growing potential of NMR-based studies of MPCs to provide critical insight into the energetics of protein–ligand and protein–protein interactions that underlie essential biological functions in cellular membranes.
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44
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Gillespie JJ, Phan IQH, Driscoll TP, Guillotte ML, Lehman SS, Rennoll-Bankert KE, Subramanian S, Beier-Sexton M, Myler PJ, Rahman MS, Azad AF. The Rickettsia type IV secretion system: unrealized complexity mired by gene family expansion. Pathog Dis 2016; 74:ftw058. [PMID: 27307105 PMCID: PMC5505475 DOI: 10.1093/femspd/ftw058] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/03/2016] [Indexed: 12/22/2022] Open
Abstract
Many prokaryotes utilize type IV secretion systems (T4SSs) to translocate substrates (e.g. nucleoprotein, DNA, protein) across the cell envelope, and/or to elaborate surface structures (i.e. pili or adhesins). Among eight distinct T4SS classes, P-T4SSs are typified by the Agrobacterium tumefaciens vir T4SS, which is comprised of 12 scaffold components (VirB1-VirB11, VirD4). While most P-T4SSs include all 12 Vir proteins, some differ from the vir archetype by either containing additional scaffold components not analogous to Vir proteins or lacking one or more of the Vir proteins. In a special case, the Rickettsiales vir homolog (rvh) P-T4SS comprises unprecedented gene family expansion. rvh contains three families of gene duplications (rvhB9, rvhB8, rvhB4): RvhB9,8,4-I are conserved relative to equivalents in other P-T4SSs, while RvhB9,8,4-II have evolved atypical features that deviate substantially from other homologs. Furthermore, rvh contains five VirB6-like genes (rvhB6a-e), which are tandemly arrayed and contain large N- and C-terminal extensions. Our work herein focuses on the complexity underpinned by rvh gene family expansion. Furthermore, we describe an RvhB10 insertion, which occurs in a region that forms the T4SS pore. The significance of these curious properties to rvh structure and function is evaluated, shedding light on a highly complex T4SS.
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Affiliation(s)
- Joseph J Gillespie
- Department of Microbiology and Immunology, University of Maryland School of Medicine, 685 W. Baltimore St., HSF I Suite 380, Baltimore, MD 21201, USA
| | - Isabelle Q H Phan
- Seattle Structural Genomics Center for Infectious Disease, 307 Westlake Ave North, Seattle, WA 98109, USA Center for Infectious Disease Research (formerly Seattle Biomedical Research Institute), Seattle, WA 98109, USA
| | - Timothy P Driscoll
- Department of Biology, West Virginia University, Life Sciences Building, PO Box 6057, Morgantown, WV 26506-6201, USA
| | - Mark L Guillotte
- Department of Microbiology and Immunology, University of Maryland School of Medicine, 685 W. Baltimore St., HSF I Suite 380, Baltimore, MD 21201, USA
| | - Stephanie S Lehman
- Department of Microbiology and Immunology, University of Maryland School of Medicine, 685 W. Baltimore St., HSF I Suite 380, Baltimore, MD 21201, USA
| | - Kristen E Rennoll-Bankert
- Department of Microbiology and Immunology, University of Maryland School of Medicine, 685 W. Baltimore St., HSF I Suite 380, Baltimore, MD 21201, USA
| | - Sandhya Subramanian
- Seattle Structural Genomics Center for Infectious Disease, 307 Westlake Ave North, Seattle, WA 98109, USA Center for Infectious Disease Research (formerly Seattle Biomedical Research Institute), Seattle, WA 98109, USA
| | - Magda Beier-Sexton
- Department of Microbiology and Immunology, University of Maryland School of Medicine, 685 W. Baltimore St., HSF I Suite 380, Baltimore, MD 21201, USA
| | - Peter J Myler
- Seattle Structural Genomics Center for Infectious Disease, 307 Westlake Ave North, Seattle, WA 98109, USA Center for Infectious Disease Research (formerly Seattle Biomedical Research Institute), Seattle, WA 98109, USA
| | - M Sayeedur Rahman
- Department of Microbiology and Immunology, University of Maryland School of Medicine, 685 W. Baltimore St., HSF I Suite 380, Baltimore, MD 21201, USA
| | - Abdu F Azad
- Department of Microbiology and Immunology, University of Maryland School of Medicine, 685 W. Baltimore St., HSF I Suite 380, Baltimore, MD 21201, USA
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45
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Gonzalez-Rivera C, Bhatty M, Christie PJ. Mechanism and Function of Type IV Secretion During Infection of the Human Host. Microbiol Spectr 2016; 4:10.1128/microbiolspec.VMBF-0024-2015. [PMID: 27337453 PMCID: PMC4920089 DOI: 10.1128/microbiolspec.vmbf-0024-2015] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2015] [Indexed: 02/07/2023] Open
Abstract
Bacterial pathogens employ type IV secretion systems (T4SSs) for various purposes to aid in survival and proliferation in eukaryotic hosts. One large T4SS subfamily, the conjugation systems, confers a selective advantage to the invading pathogen in clinical settings through dissemination of antibiotic resistance genes and virulence traits. Besides their intrinsic importance as principle contributors to the emergence of multiply drug-resistant "superbugs," detailed studies of these highly tractable systems have generated important new insights into the mode of action and architectures of paradigmatic T4SSs as a foundation for future efforts aimed at suppressing T4SS machine function. Over the past decade, extensive work on the second large T4SS subfamily, the effector translocators, has identified a myriad of mechanisms employed by pathogens to subvert, subdue, or bypass cellular processes and signaling pathways of the host cell. An overarching theme in the evolution of many effectors is that of molecular mimicry. These effectors carry domains similar to those of eukaryotic proteins and exert their effects through stealthy interdigitation of cellular pathways, often with the outcome not of inducing irreversible cell damage but rather of reversibly modulating cellular functions. This article summarizes the major developments for the actively studied pathogens with an emphasis on the structural and functional diversity of the T4SSs and the emerging common themes surrounding effector function in the human host.
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Affiliation(s)
- Christian Gonzalez-Rivera
- Department of Microbiology and Molecular Genetics, University of Texas Medical School at Houston, 6431 Fannin St, Houston, Texas 77030, Phone: 713-500-5440 (P. J. Christie); 713-500-5441 (C. Gonzalez-Rivera, M. Bhatty)
| | - Minny Bhatty
- Department of Microbiology and Molecular Genetics, University of Texas Medical School at Houston, 6431 Fannin St, Houston, Texas 77030, Phone: 713-500-5440 (P. J. Christie); 713-500-5441 (C. Gonzalez-Rivera, M. Bhatty)
| | - Peter J. Christie
- Department of Microbiology and Molecular Genetics, University of Texas Medical School at Houston, 6431 Fannin St, Houston, Texas 77030, Phone: 713-500-5440 (P. J. Christie); 713-500-5441 (C. Gonzalez-Rivera, M. Bhatty)
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46
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Peptidomimetic Small Molecules Disrupt Type IV Secretion System Activity in Diverse Bacterial Pathogens. mBio 2016; 7:e00221-16. [PMID: 27118587 PMCID: PMC4850256 DOI: 10.1128/mbio.00221-16] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Bacteria utilize complex type IV secretion systems (T4SSs) to translocate diverse effector proteins or DNA into target cells. Despite the importance of T4SSs in bacterial pathogenesis, the mechanism by which these translocation machineries deliver cargo across the bacterial envelope remains poorly understood, and very few studies have investigated the use of synthetic molecules to disrupt T4SS-mediated transport. Here, we describe two synthetic small molecules (C10 and KSK85) that disrupt T4SS-dependent processes in multiple bacterial pathogens. Helicobacter pylori exploits a pilus appendage associated with the cag T4SS to inject an oncogenic effector protein (CagA) and peptidoglycan into gastric epithelial cells. In H. pylori, KSK85 impedes biogenesis of the pilus appendage associated with the cag T4SS, while C10 disrupts cag T4SS activity without perturbing pilus assembly. In addition to the effects in H. pylori, we demonstrate that these compounds disrupt interbacterial DNA transfer by conjugative T4SSs in Escherichia coli and impede vir T4SS-mediated DNA delivery by Agrobacterium tumefaciens in a plant model of infection. Of note, C10 effectively disarmed dissemination of a derepressed IncF plasmid into a recipient bacterial population, thus demonstrating the potential of these compounds in mitigating the spread of antibiotic resistance determinants driven by conjugation. To our knowledge, this study is the first report of synthetic small molecules that impair delivery of both effector protein and DNA cargos by diverse T4SSs. Many human and plant pathogens utilize complex nanomachines called type IV secretion systems (T4SSs) to transport proteins and DNA to target cells. In addition to delivery of harmful effector proteins into target cells, T4SSs can disseminate genetic determinants that confer antibiotic resistance among bacterial populations. In this study, we sought to identify compounds that disrupt T4SS-mediated processes. Using the human gastric pathogen H. pylori as a model system, we identified and characterized two small molecules that prevent transfer of an oncogenic effector protein to host cells. We discovered that these small molecules also prevented the spread of antibiotic resistance plasmids in E. coli populations and diminished the transfer of tumor-inducing DNA from the plant pathogen A. tumefaciens to target cells. Thus, these compounds are versatile molecular tools that can be used to study and disarm these important bacterial machines.
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47
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Abstract
Conjugative transfer is the most important means of spreading antibiotic resistance and virulence factors among bacteria. The key vehicles of this horizontal gene transfer are a group of mobile genetic elements, termed conjugative plasmids. Conjugative plasmids contain as minimum instrumentation an origin of transfer (oriT), DNA-processing factors (a relaxase and accessory proteins), as well as proteins that constitute the trans-envelope transport channel, the so-called mating pair formation (Mpf) proteins. All these protein factors are encoded by one or more transfer (tra) operons that together form the DNA transport machinery, the Gram-positive type IV secretion system. However, multicellular Gram-positive bacteria belonging to the streptomycetes appear to have evolved another mechanism for conjugative plasmid spread reminiscent of the machinery involved in bacterial cell division and sporulation, which transports double-stranded DNA from donor to recipient cells. Here, we focus on the protein key players involved in the plasmid spread through the two different modes and present a new secondary structure homology-based classification system for type IV secretion protein families. Moreover, we discuss the relevance of conjugative plasmid transfer in the environment and summarize novel techniques to visualize and quantify conjugative transfer in situ.
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48
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Lento C, Ferraro M, Wilson D, Audette GF. HDX-MS and deletion analysis of the type 4 secretion system protein TraF from the Escherichia coli F plasmid. FEBS Lett 2016; 590:376-86. [PMID: 26785931 DOI: 10.1002/1873-3468.12066] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Revised: 01/08/2016] [Accepted: 01/12/2016] [Indexed: 12/26/2022]
Abstract
Conjugative DNA transfer by the F-plasmid is achieved through a type IV secretion system (T4SS) encoded within the plasmid's transfer region; TraF is one of several F-T4SS proteins essential for F-pilus assembly. In order to identify regions of the protein important for TraF function, a series of deletion mutants were assessed for their ability to recover conjugative transfer in a traF knockout. Interestingly, modification of any region of TraF abolishes pilus synthesis, resulting in a loss of rescue of conjugative function. Dynamic analysis of TraF by time-resolved hydrogen-deuterium exchange revealed that the C-terminal region containing the predicted thioredoxin-like domain is quite structured, while the N-terminal region, predicted to interact with TraH in the intact F-T4SS, was more dynamic.
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Affiliation(s)
- Cristina Lento
- Department of Chemistry, York University, Toronto, ON, Canada
| | - Michele Ferraro
- Department of Chemistry, York University, Toronto, ON, Canada
| | - Derek Wilson
- Department of Chemistry, York University, Toronto, ON, Canada.,Centre for Research on Biomolecular Interactions, York University, Toronto, ON, Canada.,Centre for Research in Mass Spectrometry, York University, Toronto, ON, Canada
| | - Gerald F Audette
- Department of Chemistry, York University, Toronto, ON, Canada.,Centre for Research on Biomolecular Interactions, York University, Toronto, ON, Canada
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49
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Kubori T, Nagai H. The Type IVB secretion system: an enigmatic chimera. Curr Opin Microbiol 2016; 29:22-9. [DOI: 10.1016/j.mib.2015.10.001] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2015] [Revised: 10/14/2015] [Accepted: 10/15/2015] [Indexed: 10/22/2022]
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50
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Abstract
Type IV secretion systems (T4SSs) are large multisubunit translocons, found in both gram-negative and gram-positive bacteria and in some archaea. These systems transport a diverse array of substrates from DNA and protein-DNA complexes to proteins, and play fundamental roles in both bacterial pathogenesis and bacterial adaptation to the cellular milieu in which bacteria live. This review describes the various biochemical and structural advances made toward understanding the biogenesis, architecture, and function of T4SSs.
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Affiliation(s)
- Vidya Chandran Darbari
- Section of Structural Biology, Department of Medicine, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom
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