1
|
Shapira N, Zusman T, Segal G. The LysR-type transcriptional regulator LelA co-regulates various effectors in different Legionella species. Mol Microbiol 2024; 121:243-259. [PMID: 38153189 DOI: 10.1111/mmi.15214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Revised: 12/05/2023] [Accepted: 12/08/2023] [Indexed: 12/29/2023]
Abstract
The intracellular pathogen Legionella pneumophila translocates more than 300 effector proteins into its host cells. The expression levels of the genes encoding these effectors are orchestrated by an intricate regulatory network. Here, we introduce LelA, the first L. pneumophila LysR-type transcriptional regulator of effectors. Through bioinformatic and experimental analyses, we identified the LelA target regulatory element and demonstrated that it directly activates the expression of three L. pneumophila effectors (legL7, legL6, and legU1). We further found that the gene encoding LelA is positively regulated by the RpoS sigma factor, thus linking it to the known effector regulatory network. Examination of other species throughout the Legionella genus revealed that this regulatory element is found upstream of 34 genes encoding validated effectors, putative effectors, and hypothetical proteins. Moreover, ten of these genes were examined and found to be activated by the L. pneumophila LelA as well as by their orthologs in the corresponding species. LelA represents a novel type of Legionella effector regulator, which coordinates the expression of both adjacently and distantly located effector-encoding genes, thus forming small groups of co-regulated effectors.
Collapse
Affiliation(s)
- Naomi Shapira
- The Shmunis School of Biomedicine and Cancer Research, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, Israel
| | - Tal Zusman
- The Shmunis School of Biomedicine and Cancer Research, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, Israel
| | - Gil Segal
- The Shmunis School of Biomedicine and Cancer Research, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, Israel
| |
Collapse
|
2
|
Bass AR, Egan MS, Alexander-Floyd J, Lopes Fischer N, Doerner J, Shin S. Human GBP1 facilitates the rupture of the Legionella-containing vacuole and inflammasome activation. mBio 2023; 14:e0170723. [PMID: 37737612 PMCID: PMC10653807 DOI: 10.1128/mbio.01707-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2023] [Accepted: 07/27/2023] [Indexed: 09/23/2023] Open
Abstract
IMPORTANCE Inflammasomes are essential for host defense against intracellular bacterial pathogens like Legionella, as they activate caspases, which promote cytokine release and cell death to control infection. In mice, interferon (IFN) signaling promotes inflammasome responses against bacteria by inducing a family of IFN-inducible GTPases known as guanylate-binding proteins (GBPs). Within murine macrophages, IFN promotes the rupture of the Legionella-containing vacuole (LCV), while GBPs are dispensable for this process. Instead, GBPs facilitate the lysis of cytosol-exposed Legionella. In contrast, the functions of IFN and GBPs in human inflammasome responses to Legionella are poorly understood. We show that IFN-γ enhances inflammasome responses to Legionella in human macrophages. Human GBP1 is required for these IFN-γ-driven inflammasome responses. Furthermore, GBP1 co-localizes with Legionella and/or LCVs in a type IV secretion system (T4SS)-dependent manner and promotes damage to the LCV, which leads to increased exposure of the bacteria to the host cell cytosol. Thus, our findings reveal species- and pathogen-specific differences in how GBPs function to promote inflammasome responses.
Collapse
Affiliation(s)
- Antonia R. Bass
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Marisa S. Egan
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Jasmine Alexander-Floyd
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Natasha Lopes Fischer
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Jessica Doerner
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Sunny Shin
- Department of Microbiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| |
Collapse
|
3
|
Yang JL, Li D, Zhan XY. Concept about the Virulence Factor of Legionella. Microorganisms 2022; 11:microorganisms11010074. [PMID: 36677366 PMCID: PMC9867486 DOI: 10.3390/microorganisms11010074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 12/23/2022] [Accepted: 12/23/2022] [Indexed: 12/29/2022] Open
Abstract
Pathogenic species of Legionella can infect human alveolar macrophages through Legionella-containing aerosols to cause a disease called Legionellosis, which has two forms: a flu-like Pontiac fever and severe pneumonia named Legionnaires' disease (LD). Legionella is an opportunistic pathogen that frequently presents in aquatic environments as a biofilm or protozoa parasite. Long-term interaction and extensive co-evolution with various genera of amoebae render Legionellae pathogenic to infect humans and also generate virulence differentiation and heterogeneity. Conventionally, the proteins involved in initiating replication processes and human macrophage infections have been regarded as virulence factors and linked to pathogenicity. However, because some of the virulence factors are associated with the infection of protozoa and macrophages, it would be more accurate to classify them as survival factors rather than virulence factors. Given that the molecular basis of virulence variations among non-pathogenic, pathogenic, and highly pathogenic Legionella has not yet been elaborated from the perspective of virulence factors, a comprehensive explanation of how Legionella infects its natural hosts, protozoans, and accidental hosts, humans is essential to show a novel concept regarding the virulence factor of Legionella. In this review, we overviewed the pathogenic development of Legionella from protozoa, the function of conventional virulence factors in the infections of protozoa and macrophages, the host's innate immune system, and factors involved in regulating the host immune response, before discussing a probably new definition for the virulence factors of Legionella.
Collapse
|
4
|
Wachter S, Cockrell DC, Miller HE, Virtaneva K, Kanakabandi K, Darwitz B, Heinzen RA, Beare PA. The endogenous Coxiella burnetii plasmid encodes a functional toxin-antitoxin system. Mol Microbiol 2022; 118:744-764. [PMID: 36385554 PMCID: PMC10098735 DOI: 10.1111/mmi.15001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 10/25/2022] [Accepted: 11/08/2022] [Indexed: 11/18/2022]
Abstract
Coxiella burnetii is the causative agent of Q fever. All C. burnetii isolates encode either an autonomously replicating plasmid (QpH1, QpDG, QpRS, or QpDV) or QpRS-like chromosomally integrated plasmid sequences. The role of the ORFs present in these sequences is unknown. Here, the role of the ORFs encoded on QpH1 was investigated. Using a new C. burnetii shuttle vector (pB-TyrB-QpH1ori), we cured the C. burnetii Nine Mile Phase II strain of QpH1. The ΔQpH1 strain grew normally in axenic media but had a significant growth defect in Vero cells, indicating QpH1 was important for C. burnetii virulence. We developed an inducible CRISPR interference system to examine the role of individual QpH1 plasmid genes. CRISPRi of cbuA0027 resulted in significant growth defects in axenic media and THP-1 cells. The cbuA0028/cbuA0027 operon encodes CBUA0028 (ToxP) and CBUA0027 (AntitoxP), which are homologous to the HigB2 toxin and HigA2 antitoxin, respectively, from Vibrio cholerae. Consistent with toxin-antitoxin systems, overexpression of toxP resulted in a severe intracellular growth defect that was rescued by co-expression of antitoxP. ToxP inhibited protein translation. AntitoxP bound the toxP promoter (PtoxP) and ToxP, with the resulting complex binding also PtoxP. In summary, our data indicate that C. burnetii maintains an autonomously replicating plasmid because of a plasmid-based toxin-antitoxin system.
Collapse
Affiliation(s)
- Shaun Wachter
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA.,Vaccine and Infectious Disease Organization, Saskatoon, Saskatchewan, Canada
| | - Diane C Cockrell
- Vector-Pathogen-Host Interaction unit, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
| | | | - Kimmo Virtaneva
- Genomics Research Section, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
| | - Kishore Kanakabandi
- Genomics Research Section, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
| | - Benjamin Darwitz
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Robert A Heinzen
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
| | - Paul A Beare
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA.,Genomics Research Section, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
| |
Collapse
|
5
|
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.
Collapse
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
| |
Collapse
|
6
|
Abstract
Legionella pneumophila, the causative agent of Legionnaires' disease, is a facultative intracellular pathogen that survives inside phagocytic host cells by establishing a protected replication niche, termed the "Legionella-containing vacuole" (LCV). To form an LCV and subvert pivotal host pathways, L. pneumophila employs a type IV secretion system (T4SS), which translocates more than 300 different effector proteins into the host cell. The L. pneumophila T4SS complex has been shown to span the bacterial cell envelope at the bacterial poles. However, the interactions between the T4SS and the LCV membrane are not understood. Using cryo-focused ion beam milling, cryo-electron tomography, and confocal laser scanning fluorescence microscopy, we show that up to half of the intravacuolar L. pneumophila bacteria tether their cell pole to the LCV membrane. Tethering coincides with the presence and function of T4SSs and likely promotes the establishment of distinct contact sites between T4SSs and the LCV membrane. Contact sites are characterized by indentations in the limiting LCV membrane and localize juxtaposed to T4SS machineries. The data are in agreement with the notion that effector translocation occurs by close membrane contact rather than by an extended pilus. Our findings provide novel insights into the interactions of the L. pneumophila T4SS with the LCV membrane in situ. IMPORTANCE Legionnaires' disease is a life-threatening pneumonia, which is characterized by high fever, coughing, shortness of breath, muscle pain, and headache. The disease is caused by the amoeba-resistant bacterium L. pneumophila found in various soil and aquatic environments and is transmitted to humans via the inhalation of small bacteria-containing droplets. An essential virulence factor of L. pneumophila is a so-called "type IV secretion system" (T4SS), which, by injecting a plethora of "effector proteins" into the host cell, determines pathogen-host interactions and the formation of a distinct intracellular compartment, the "Legionella-containing vacuole" (LCV). It is unknown how the T4SS makes contact to the LCV membrane to deliver the effectors. In this study, we identify indentations in the host cell membrane in close proximity to functional T4SSs localizing at the bacterial poles. Our work reveals first insights into the architecture of Legionella-LCV contact sites.
Collapse
|
7
|
Kawashiro A, Okubo T, Nakamura S, Thapa J, Miyake M, Yamaguchi H. Wild ciliates differ in susceptibility to Legionella pneumophila JR32. MICROBIOLOGY-SGM 2021; 167. [PMID: 34402779 DOI: 10.1099/mic.0.001078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
We investigated how Legionella pneumophila (Lp) JR32 interacts with Anteglaucoma CS11A and Colpoda E6, two ciliates that we isolated from sewage and sink trap sludge, respectively, using a handmade maze device containing a 96-well crafting plate. Our 18S rDNA-based phylogenetic analysis showed that Anteglaucoma CS11A and Colpoda E6 formed distinct clades. Scanning electron microscopy showed that Anteglaucoma CS11A had a bigger-sized body than Colpoda E6 and, unlike Tetrahymena IB (the reference strain), neither ciliate produced pellets, which are extracellular vacuoles. Fluorescence microscopic observations revealed that although the intake amounts differed, all three ciliates rapidly ingested LpJR32 regardless of the presence or absence of the icm/dot virulence genes, indicating that they all interacted with LpJR32. In co-cultures with Anteglaucoma CS11A, the LpJR32 levels were maintained but fell dramatically when the co-culture contained the LpJR32 icm/dot deletion mutant instead. Anteglaucoma CS11A died within 2 days of co-culture with LpJR32, but survived co-culture with the deletion mutant. In co-cultures with Colpoda E6, LpJR32 levels were maintained but temporarily decreased independently of the virulence gene. Concurrently, the Colpoda E6 ciliates survived by forming cysts, which may enable them to resist harsh environments, and by diminishing the sensitivity of trophozoites to Lp. In the Tetrahymena IB co-cultures with LpJR32 or Δicm/dot, the Lp levels were maintained, albeit with temporal decreases, and the Tetrahymena IB levels were also maintained. We conclude that unlike Tetrahymena IB with pellet production, Anteglaucoma CS11A can be killed by LpJR32 infection, and Colpoda E6 can resist LpJR32 infection through cyst formation and the low sensitivity of trophozoites to Lp. Thus, the two ciliates that we isolated had different susceptibilities to LpJR32 infection.
Collapse
Affiliation(s)
- Airi Kawashiro
- Department of Medical Laboratory Science, Faculty of Health Sciences, Hokkaido University, Sapporo, Japan
| | - Torahiko Okubo
- Department of Medical Laboratory Science, Faculty of Health Sciences, Hokkaido University, Sapporo, Japan
| | - Shinji Nakamura
- Division of Biomedical Imaging Research, Juntendo University Graduate School of Medicine, Tokyo, Japan
| | - Jeewan Thapa
- Department of Medical Laboratory Science, Faculty of Health Sciences, Hokkaido University, Sapporo, Japan.,Division of Bioresources Research Center for Zoonosis Control, Hokkaido University, Hokkaido, Sapporo, Japan
| | - Masaki Miyake
- Laboratory of Microbiology and Immunology, School of Pharmaceutical Sciences, University of Shizuoka, Shizuoka, Japan
| | - Hiroyuki Yamaguchi
- Department of Medical Laboratory Science, Faculty of Health Sciences, Hokkaido University, Sapporo, Japan
| |
Collapse
|
8
|
Jiang C, Huang X, Yao J, Yu L, Wei F, Yang A. The role of membrane contact sites at the bacteria-host interface. Crit Rev Microbiol 2021; 48:270-282. [PMID: 34403642 DOI: 10.1080/1040841x.2021.1961678] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Membrane contact sites (MCSs) refer to the areas of close proximity between heterologous membranes. A growing body of evidence indicates that MCSs are involved in important cellular functions, such as cellular material transfer, organelle biogenesis, and cell growth. Importantly, the study of MCSs at the bacteria-host interface is an emerging popular research topic. Intracellular bacterial pathogens have evolved a variety of fascinating strategies to interfere with MCSs by injecting effectors into infected host cells. Bacteria-containing vacuoles establish direct physical contact with organelles within the host, ensuring vacuolar membrane integrity and energy supply from host organelles and protecting the vacuoles from the host endocytic pathway and lysosomal degradation. An increasing number of bacterial effectors from various bacterial pathogens hijack components of host MCSs to form the vacuole-organelle MCSs for material exchange. MCS-related events have been identified as new mechanisms of microbial pathogenesis to greatly improve bacterial survival and replication within host cells. In this review, we will discuss the recent advances in MCSs at the bacteria-host interface, focussing on the roles of MCSs mediated by bacterial effectors in microbial pathogenesis.
Collapse
Affiliation(s)
- Chen Jiang
- School of Life Sciences, Chongqing University, Chongqing, China
| | - Xue Huang
- School of Life Sciences, Chongqing University, Chongqing, China
| | - Jia Yao
- School of Life Sciences, Chongqing University, Chongqing, China
| | - Lihua Yu
- School of Life Sciences, Chongqing University, Chongqing, China
| | - Fujing Wei
- School of Life Sciences, Chongqing University, Chongqing, China
| | - Aimin Yang
- School of Life Sciences, Chongqing University, Chongqing, China
| |
Collapse
|
9
|
Linsky M, Segal G. A horizontally acquired Legionella genomic island encoding a LuxR type regulator and effector proteins displays variation in gene content and regulation. Mol Microbiol 2021; 116:766-782. [PMID: 34120381 DOI: 10.1111/mmi.14770] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Revised: 06/11/2021] [Accepted: 06/11/2021] [Indexed: 11/30/2022]
Abstract
The intracellular pathogen Legionella pneumophila translocates >300 effector proteins into host cells, many of which are regulated at the transcriptional level. Here, we describe a novel L. pneumophila genomic island, which undergoes horizontal gene transfer within the Legionella genus. This island encodes two Icm/Dot effectors: LegK3 and a previously uncharacterized effector which we named CegK3, as well as a LuxR type regulator, which we named RegK3. Analysis of this island in different Legionella species revealed a conserved regulatory element located upstream to the effector-encoding genes in the island. Further analyses, including gene expression analysis, mutagenesis of the RegK3 regulatory element, controlled expression studies, and gel-mobility shift assays, all demonstrate that RegK3 directly activates the expression levels of legK3 and cegK3 effector-encoding genes. Additionally, the expression of all the components of the island is silenced by the Fis repressors. Comparison of expression profiles of these three genes among different Legionella species revealed variability in the activation levels mediated by RegK3, which were positively correlated with the Fis-mediated repression. Furthermore, LegK3 and CegK3 effectors moderately inhibit yeast growth, and importantly, they have a strong synergistic inhibitory effect on yeast growth, suggesting these two effectors are not only co-regulated but also might function together.
Collapse
Affiliation(s)
- Marika Linsky
- The Shmunis School of Biomedicine and Cancer Research, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, Israel
| | - Gil Segal
- The Shmunis School of Biomedicine and Cancer Research, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, Israel
| |
Collapse
|
10
|
Demircan T, Hacıbektaşoğlu H, Sibai M, Fesçioğlu EC, Altuntaş E, Öztürk G, Süzek BE. Preclinical Molecular Signatures of Spinal Cord Functional Restoration: Optimizing the Metamorphic Axolotl ( Ambystoma mexicanum) Model in Regenerative Medicine. OMICS-A JOURNAL OF INTEGRATIVE BIOLOGY 2021; 24:370-378. [PMID: 32496969 DOI: 10.1089/omi.2020.0024] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Regenerative medicine offers hope for patients with diseases of the central and peripheral nervous system. Urodele amphibians such as axolotl display an exceptional regenerative capacity and are considered as essential preclinical model organisms in neurology and regenerative medicine research. Earlier studies have suggested that the limb regeneration ability of this salamander notably decreases with induction of metamorphosis by thyroid hormones. Metamorphic axolotl requires further validation as a negative control in preclinical regenerative medicine research, not to mention the study of molecular substrates of its regenerative abilities. In this study, we report new observations on the effect of experimentally induced metamorphosis on spinal cord regeneration in axolotl. Surprisingly, we found that metamorphic animals were successful to functionally restore the spinal cord after an experimentally induced injury. To discern the molecular signatures of spinal cord regeneration, we performed transcriptomics analyses at 1- and 7-days postinjury (dpi) for both spinal cord injury (SCI)-induced (experimental) and laminectomy (sham) groups. We observed 119 and 989 differentially expressed genes at 1- and 7-dpi, respectively, while the corresponding mouse orthologous genes were enriched in junction-, immune system-, and extracellular matrix-related pathways. Taken together, our findings challenge the prior notions of limited regenerative ability of metamorphic axolotl which exhibited successful spinal cord regeneration in our experience. Moreover, we report on molecular signatures that can potentially explain the mechanistic substrates of the regenerative capacity of the metamorphic axolotl. To the best of our knowledge, this is the first report on molecular responses to SCI and functional restoration in metamorphic axolotls. These new findings advance our understanding of spinal cord regeneration, and may thus help optimize the future use of axolotl as a preclinical model in regenerative medicine and integrative biology fields.
Collapse
Affiliation(s)
- Turan Demircan
- Department of Medical Biology, School of Medicine, Mugla Sitki Kocman University, Mugla, Turkey.,Regenerative and Restorative Medicine Research Center (REMER), Istanbul Medipol University, Istanbul, Turkey
| | - Harbiye Hacıbektaşoğlu
- Regenerative and Restorative Medicine Research Center (REMER), Istanbul Medipol University, Istanbul, Turkey
| | - Mustafa Sibai
- Graduate School of Natural and Applied Sciences, Mugla Sitki Kocman University, Mugla, Turkey
| | - Ece Cana Fesçioğlu
- Regenerative and Restorative Medicine Research Center (REMER), Istanbul Medipol University, Istanbul, Turkey
| | - Ebru Altuntaş
- Graduate School of Natural and Applied Sciences, Mugla Sitki Kocman University, Mugla, Turkey
| | - Gürkan Öztürk
- Department of Physiology, International School of Medicine, Istanbul Medipol University, Istanbul, Turkey
| | - Barış Ethem Süzek
- Department of Computer Engineering, Faculty of Engineering, Mugla Sitki Kocman University, Mugla, Turkey
| |
Collapse
|
11
|
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.
Collapse
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
| |
Collapse
|
12
|
Thomas DR, Newton P, Lau N, Newton HJ. Interfering with Autophagy: The Opposing Strategies Deployed by Legionella pneumophila and Coxiella burnetii Effector Proteins. Front Cell Infect Microbiol 2020; 10:599762. [PMID: 33251162 PMCID: PMC7676224 DOI: 10.3389/fcimb.2020.599762] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 10/13/2020] [Indexed: 12/14/2022] Open
Abstract
Autophagy is a fundamental and highly conserved eukaryotic process, responsible for maintaining cellular homeostasis and releasing nutrients during times of starvation. An increasingly important function of autophagy is its role in the cell autonomous immune response; a process known as xenophagy. Intracellular pathogens are engulfed by autophagosomes and targeted to lysosomes to eliminate the threat to the host cell. To counteract this, many intracellular bacterial pathogens have developed unique approaches to overcome, evade, or co-opt host autophagy to facilitate a successful infection. The intracellular bacteria Legionella pneumophila and Coxiella burnetii are able to avoid destruction by the cell, causing Legionnaires' disease and Q fever, respectively. Despite being related and employing homologous Dot/Icm type 4 secretion systems (T4SS) to translocate effector proteins into the host cell, these pathogens have developed their own unique intracellular niches. L. pneumophila evades the host endocytic pathway and instead forms an ER-derived vacuole, while C. burnetii requires delivery to mature, acidified endosomes which it remodels into a large, replicative vacuole. Throughout infection, L. pneumophila effectors act at multiple points to inhibit recognition by xenophagy receptors and disrupt host autophagy, ensuring it avoids fusion with destructive lysosomes. In contrast, C. burnetii employs its effector cohort to control autophagy, hypothesized to facilitate the delivery of nutrients and membrane to support the growing vacuole and replicating bacteria. In this review we explore the effector proteins that these two organisms utilize to modulate the host autophagy pathway in order to survive and replicate. By better understanding how these pathogens manipulate this highly conserved pathway, we can not only develop better treatments for these important human diseases, but also better understand and control autophagy in the context of human health and disease.
Collapse
Affiliation(s)
| | | | | | - Hayley J. Newton
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, VIC, Australia
| |
Collapse
|
13
|
Legionella pneumophila Excludes Autophagy Adaptors from the Ubiquitin-Labeled Vacuole in Which It Resides. Infect Immun 2020; 88:IAI.00793-19. [PMID: 32482642 DOI: 10.1128/iai.00793-19] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Accepted: 05/22/2020] [Indexed: 01/07/2023] Open
Abstract
Xenophagy targets intracellular pathogens for destruction by the host autophagy pathway. Ubiquitin chains are conjugated to xenophagic targets and recruit multiple autophagy adaptors. The intracellular pathogen Legionella pneumophila resides in a vacuole that is ubiquitinated; however, this pathogen avoids xenophagic detection. Here, the mechanisms by which L. pneumophila can prevent the host xenophagy pathway from targeting the vacuole in which it resides were examined. Ubiquitin-labeled vacuoles containing L. pneumophila failed to recruit autophagy adaptors by a process that was independent of RavZ function. Coinfection studies were conducted using a strain of Listeria monocytogenes that served as a robust xenophagic target. Legionella pneumophila infection blocked xenophagic targeting of L. monocytogenes by a RavZ-dependent mechanism. Importantly, when coinfection studies were conducted with a RavZ-deficient strain of L. pneumophila, L. monocytogenes was targeted by the host xenophagy system but vacuoles containing L. pneumophila avoided targeting. Enhanced adaptor recruitment to the vacuole was observed by using a strain of L. pneumophila in which all of the effector proteins in the SidE family were deleted; however, this strain was still not targeted by the host autophagy pathway. Thus, there are at least two pathways by which L. pneumophila can disrupt xenophagic targeting of the vacuole in which it resides. One mechanism involves global disruption of the host autophagy machinery by the effector protein RavZ. A second cis-acting mechanism prevents the binding of autophagy adaptors to the ubiquitin-decorated surface of the L. pneumophila-containing vacuole.
Collapse
|
14
|
Lalancette C, Leduc JM, Malo J, Fournier É, Saoud J, Faucher SP, Pacheco AL, Bernard K, Martineau C, Lévesque S. Legionella quinlivanii strain isolated from a human: A case report and whole genome sequencing analysis. JOURNAL OF THE ASSOCIATION OF MEDICAL MICROBIOLOGY AND INFECTIOUS DISEASE CANADA = JOURNAL OFFICIEL DE L'ASSOCIATION POUR LA MICROBIOLOGIE MEDICALE ET L'INFECTIOLOGIE CANADA 2020; 5:112-114. [PMID: 36338178 PMCID: PMC9602882 DOI: 10.3138/jammi-2019-0021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 11/12/2019] [Indexed: 06/16/2023]
Abstract
We describe a strain of Legionella quinlivanii isolated from a bronchoalveolar lavage specimen from an 83-year-old patient in the province of Québec. Identification was done using 16S rRNA sequencing. The strain could replicate efficiently in human THP-1 macrophages and maintained a low level of cytotoxicity. Upon analyzing the whole genome sequencing data, the icm/dot secretion system was present, but the strain lacked some effector genes known to express proteins toxic to cells. The pathogenicity of this Legionella species should be investigated further.
Collapse
Affiliation(s)
- Cindy Lalancette
- Laboratoire de santé publique du Québec, Institut national de santé publique du Québec, Sainte-Anne-de-Bellevue, Québec, Canada
| | | | - Jacques Malo
- Hôpital du Sacré-Cœur de Montréal, Montréal, Québec, Canada
| | - Éric Fournier
- Laboratoire de santé publique du Québec, Institut national de santé publique du Québec, Sainte-Anne-de-Bellevue, Québec, Canada
| | - Joseph Saoud
- Department of Natural Resource Sciences, Faculty of Agricultural and Environmental Sciences, McGill University, Sainte-Anne-de-Bellevue, Québec, Canada
| | - Sébastien P Faucher
- Department of Natural Resource Sciences, Faculty of Agricultural and Environmental Sciences, McGill University, Sainte-Anne-de-Bellevue, Québec, Canada
| | - Ana Luisa Pacheco
- Public Health Agency of Canada, National Microbiology Laboratory, Winnipeg, Manitoba, Canada
| | - Kathryn Bernard
- Public Health Agency of Canada, National Microbiology Laboratory, Winnipeg, Manitoba, Canada
| | - Christine Martineau
- Laboratoire de santé publique du Québec, Institut national de santé publique du Québec, Sainte-Anne-de-Bellevue, Québec, Canada
| | - Simon Lévesque
- CIUSSS de l'Estrie - CHUS, Sherbrooke, Québec, Canada
- Département de microbiologie et infectiologie, Faculté de médecine et des sciences de la santé, Université de Sherbrooke, Sherbrooke, Québec, Canada
| |
Collapse
|
15
|
Kuba M, Neha N, Newton P, Lee YW, Bennett-Wood V, Hachani A, De Souza DP, Nijagal B, Dayalan S, Tull D, McConville MJ, Sansom FM, Newton HJ. EirA Is a Novel Protein Essential for Intracellular Replication of Coxiella burnetii. Infect Immun 2020; 88:e00913-19. [PMID: 32205404 PMCID: PMC7240097 DOI: 10.1128/iai.00913-19] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 03/18/2020] [Indexed: 02/06/2023] Open
Abstract
The zoonotic bacterial pathogen Coxiella burnetii is the causative agent of Q fever, a febrile illness which can cause a serious chronic infection. C. burnetii is a unique intracellular bacterium which replicates within host lysosome-derived vacuoles. The ability of C. burnetii to replicate within this normally hostile compartment is dependent on the activity of the Dot/Icm type 4B secretion system. In a previous study, a transposon mutagenesis screen suggested that the disruption of the gene encoding the novel protein CBU2072 rendered C. burnetii incapable of intracellular replication. This protein, subsequently named EirA (essential for intracellular replication A), is indispensable for intracellular replication and virulence, as demonstrated by infection of human cell lines and in vivo infection of Galleria mellonella The putative N-terminal signal peptide is essential for protein function but is not required for localization of EirA to the bacterial inner membrane compartment and axenic culture supernatant. In the absence of EirA, C. burnetii remains viable but nonreplicative within the host phagolysosome, as coinfection with C. burnetii expressing native EirA rescues the replicative defect in the mutant strain. In addition, while the bacterial ultrastructure appears to be intact, there is an altered metabolic profile shift in the absence of EirA, suggesting that EirA may impact overall metabolism. Most strikingly, in the absence of EirA, Dot/Icm effector translocation was inhibited even when EirA-deficient C. burnetii replicated in the wild type (WT)-supported Coxiella containing vacuoles. EirA may therefore have a novel role in the control of Dot/Icm activity and represent an important new therapeutic target.
Collapse
Affiliation(s)
- Miku Kuba
- Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Nitika Neha
- Metabolomics Australia, The Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria, Australia
- Asia-Pacific Centre for Animal Health, Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, Victoria, Australia
| | - Patrice Newton
- Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Yi Wei Lee
- Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Vicki Bennett-Wood
- Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Abderrahman Hachani
- Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - David P De Souza
- Metabolomics Australia, The Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria, Australia
| | - Brunda Nijagal
- Metabolomics Australia, The Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria, Australia
| | - Saravanan Dayalan
- Metabolomics Australia, The Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria, Australia
| | - Dedreia Tull
- Metabolomics Australia, The Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria, Australia
| | - Malcolm J McConville
- Metabolomics Australia, The Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria, Australia
- Department of Biochemistry and Molecular Biology, The Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria, Australia
| | - Fiona M Sansom
- Asia-Pacific Centre for Animal Health, Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, University of Melbourne, Parkville, Victoria, Australia
| | - Hayley J Newton
- Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| |
Collapse
|
16
|
Reuter T, Vorwerk S, Liss V, Chao TC, Hensel M, Hansmeier N. Proteomic Analysis of Salmonella-modified Membranes Reveals Adaptations to Macrophage Hosts. Mol Cell Proteomics 2020; 19:900-912. [PMID: 32102972 PMCID: PMC7196581 DOI: 10.1074/mcp.ra119.001841] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Revised: 02/24/2020] [Indexed: 01/19/2023] Open
Abstract
Systemic infection and proliferation of intracellular pathogens require the biogenesis of a growth-stimulating compartment. The gastrointestinal pathogen Salmonella enterica commonly forms highly dynamic and extensive tubular membrane compartments built from Salmonella-modified membranes (SMMs) in diverse host cells. Although the general mechanism involved in the formation of replication-permissive compartments of S. enterica is well researched, much less is known regarding specific adaptations to different host cell types. Using an affinity-based proteome approach, we explored the composition of SMMs in murine macrophages. The systematic characterization provides a broader landscape of host players to the maturation of Salmonella-containing compartments and reveals core host elements targeted by Salmonella in macrophages as well as epithelial cells. However, we also identified subtle host specific adaptations. Some of these observations, such as the differential involvement of the COPII system, Rab GTPases 2A, 8B, 11 and ER transport proteins Sec61 and Sec22B may explain cell line-dependent variations in the pathophysiology of Salmonella infections. In summary, our system-wide approach demonstrates a hitherto underappreciated impact of the host cell type in the formation of intracellular compartments by Salmonella.
Collapse
Affiliation(s)
- Tatjana Reuter
- CellNanOs - Center for Cellular Nanoanalytics Osnabrück, School of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany
| | - Stephanie Vorwerk
- CellNanOs - Center for Cellular Nanoanalytics Osnabrück, School of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany
| | - Viktoria Liss
- Division of Microbiology, School of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany
| | - Tzu-Chiao Chao
- Institute of Environmental Change and Society, Department of Biology, University of Regina, Regina, Canada
| | - Michael Hensel
- Division of Microbiology, School of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany; CellNanOs - Center for Cellular Nanoanalytics Osnabrück, School of Biology/Chemistry, University of Osnabrück, Osnabrück, Germany.
| | - Nicole Hansmeier
- Department of Biology, Faculty of Science, Luther College at University of Regina, Regina, Canada.
| |
Collapse
|
17
|
Belyi Y. Targeting Eukaryotic mRNA Translation by Legionella pneumophila. Front Mol Biosci 2020; 7:80. [PMID: 32411722 PMCID: PMC7201127 DOI: 10.3389/fmolb.2020.00080] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Accepted: 04/07/2020] [Indexed: 02/01/2023] Open
Abstract
Legionella is a gram-negative microorganism and an infectious agent of pneumonia in humans. It is an intracellular pathogen and multiplies in different eukaryotic cells like amoebae, ciliated protozoa, macrophages, monocytes, and lung epithelial cells. Proliferation of L. pneumophila in eukaryotic cells depends on its type 4 secretion system, which delivers an arsenal of bacterial effector proteins to cytoplasm of its host. Once within the cytoplasm, effectors modify a broad range of host activities, including mRNA translation. Translation is inhibited by Legionella through the action of several effector proteins including Lgt1, Lgt2, Lgt3, SidI, LegK4, SidL, and RavX. Lgt1-3 and SidI target elongation factors: Lgt1-3 mono-glucosylate elongation factor eEF1A, while SidI binds eEF1A, and eEF1Bγ. Effector LegK4 inhibits protein synthesis by phosphorylating Hsp70 proteins, while SidL and RavX have no defined targets in protein synthesis machinery thus far. In addition to direct inhibition of protein synthesis, SidI also affects the stress response, whereas Lgt1-3 – unfolded protein response and cell-cycle progression of host cells. Whether manipulation of these processes is linked to canonical or non-canonical function(s) of targeted elongation factors remains unknown.
Collapse
Affiliation(s)
- Yury Belyi
- Gamaleya Research Centre for Epidemiology and Microbiology, Moscow, Russia
| |
Collapse
|
18
|
Ammanathan V, Vats S, Abraham IM, Manjithaya R. Xenophagy in cancer. Semin Cancer Biol 2020; 66:163-170. [PMID: 32126260 DOI: 10.1016/j.semcancer.2020.02.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Accepted: 02/17/2020] [Indexed: 12/24/2022]
Abstract
Macroautophagy (herein autophagy) is an intracellular pathway in which cytoplasmic components are captured by double-membrane vesicles (autophagosomes) that eventually fuse with lysosomes to degrade the cargo. Basal levels of autophagy in all eukaryotic cells maintain cellular homeostasis and under conditions of stress, organelles and proteins not essential for survival are degraded. Apart from these functions, cargoes like aggregated proteins, damaged organelles and intracellular pathogens, which are otherwise harmful to cells, are also selectively captured by autophagy and are destined for degradation. In terms of infectious diseases, pathogens are cleared by a specific form of autophagy known as xenophagy. This lysosomal mediated degradation of pathogens also increases the antigen presentation of cells thereby inducing a further immune response. The process of xenophagy provides a broad spectrum of defense mechanism to capture bacterial, viral and protozoan pathogens. However, pathogens have developed ingenious mechanisms to modulate xenophagy to enhance their intracellular survival. Meanwhile, certain pathogens also induce deleterious effects such as chronic inflammation and overexpression of oncogenes in the host system. This over time can increase the susceptibility of the host for tumorigenesis. Hence targeting tumor through anti-microbial mechanisms like xenophagy could be a novel strategy for combinatorial anti-cancer therapy. The recent developments in understanding the role of xenophagy in combating cancer causing pathogens will be discussed in this review.
Collapse
Affiliation(s)
- Veena Ammanathan
- Jawaharlal Nehru Centre for Advanced Scientific Research, 560064, Bangalore, India
| | - Somya Vats
- Jawaharlal Nehru Centre for Advanced Scientific Research, 560064, Bangalore, India
| | - Irine Maria Abraham
- Jawaharlal Nehru Centre for Advanced Scientific Research, 560064, Bangalore, India
| | - Ravi Manjithaya
- Jawaharlal Nehru Centre for Advanced Scientific Research, 560064, Bangalore, India
| |
Collapse
|
19
|
A Novel Legionella Genomic Island Encodes a Copper-Responsive Regulatory System and a Single Icm/Dot Effector Protein Transcriptionally Activated by Copper. mBio 2020; 11:mBio.03232-19. [PMID: 31992628 PMCID: PMC6989116 DOI: 10.1128/mbio.03232-19] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Legionella pneumophila is an intracellular human pathogen that utilizes amoebae as its environmental host. The adaptation of L. pneumophila to the intracellular environment requires coordination of expression of its multicomponent pathogenesis system, which is composed of a secretion system and effector proteins. However, the regulatory factors controlling the expression of this pathogenesis system are only partially uncovered. Here, we discovered a novel regulatory system that is activated by copper and controls the expression of a single effector protein. The genes encoding both the regulatory system and the effector protein are located on a genomic island that undergoes horizontal gene transfer within the Legionella genus. This regulator-effector genomic island represents the first reported case of local regulation of effectors in Legionella. The discovery of this regulatory mechanism is an important step forward in the understanding of how the regulatory network of effectors functions and evolves in the Legionella genus. The intracellular pathogen Legionella pneumophila utilizes the Icm/Dot type IV secretion system to translocate >300 effector proteins into host cells during infection. The regulation of some of these effector-encoding genes was previously shown to be coordinated by several global regulators, including three two-component systems (TCSs) found in all the Legionella species examined. Here, we describe the first Legionella genomic island encoding a single Icm/Dot effector and a dedicated TCS, which regulates its expression. This genomic island, which we named Lci, undergoes horizontal gene transfer in the Legionella genus, and the TCS encoded from this island (LciRS) is homologous to TCSs that control the expression of various metal resistance systems found in other bacteria. We found that the L. pneumophila sensor histidine kinase LciS is specifically activated by copper via a unique, small periplasmic sensing domain. Upon activation by LciS, the response regulator LciR directly binds to a conserved regulatory element and activates the expression of the adjacently located lciE effector-encoding gene. Thus, LciR represents the first local regulator of effectors identified in L. pneumophila. Moreover, we found that the expression of the lciRS operon is repressed by the Fis1 and Fis3 regulators, leading to Fis-mediated effects on copper induction of LciE and silencing of the expression of this genomic island in the absence of copper. This island represents a novel type of effector regulation in Legionella, shedding new light on the ways by which the Legionella pathogenesis system evolves its effector repertoire and expands its activating signals.
Collapse
|
20
|
Abeyrathna SS, Abeyrathna NS, Thai NK, Sarkar P, D'Arcy S, Meloni G. IroT/MavN Is a Legionella Transmembrane Fe(II) Transporter: Metal Selectivity and Translocation Kinetics Revealed by in Vitro Real-Time Transport. Biochemistry 2019; 58:4337-4342. [PMID: 31589416 DOI: 10.1021/acs.biochem.9b00658] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
In intravacuolar pathogens, iron is essential for growth and virulence. In Legionella pneumophila, a putative transmembrane protein inserted on the surface of the host pathogen-containing vacuole, IroT/MavN, facilitates intravacuolar iron acquisition from the host by an unknown mechanism, bypassing the problem of Fe(III) insolubility and mobilization. We developed a platform for purification and reconstitution of IroT in artificial lipid bilayer vesicles (proteoliposomes). By encapsulating the fluorescent reporter probe Fluozin-3, we reveal, by real-time metal transport assays, that IroT is a high-affinity iron transporter selective for Fe(II) over other essential transition metals. Mutational analysis reveals important residues in the transmembrane helices, soluble domains, and loops important for substrate recognition and translocation. The work establishes the substrate transport properties in a novel transporter family important for iron acquisition at the host-pathogen intravacuolar interface and provides chemical tools for a comparative investigation of the translocation properties in other iron transporter families.
Collapse
Affiliation(s)
- Sameera S Abeyrathna
- Department of Chemistry and Biochemistry , The University of Texas at Dallas , Richardson , Texas 75080 , United States
| | - Nisansala S Abeyrathna
- Department of Chemistry and Biochemistry , The University of Texas at Dallas , Richardson , Texas 75080 , United States
| | - Nathan Khoi Thai
- Department of Chemistry and Biochemistry , The University of Texas at Dallas , Richardson , Texas 75080 , United States
| | - Prithwijit Sarkar
- Department of Biological Sciences , The University of Texas at Dallas , Richardson , Texas 75080 , United States
| | - Sheena D'Arcy
- Department of Chemistry and Biochemistry , The University of Texas at Dallas , Richardson , Texas 75080 , United States.,Department of Biological Sciences , The University of Texas at Dallas , Richardson , Texas 75080 , United States
| | - Gabriele Meloni
- Department of Chemistry and Biochemistry , The University of Texas at Dallas , Richardson , Texas 75080 , United States
| |
Collapse
|
21
|
Stamm CE, Pasko BL, Chaisavaneeyakorn S, Franco LH, Nair VR, Weigele BA, Alto NM, Shiloh MU. Screening Mycobacterium tuberculosis Secreted Proteins Identifies Mpt64 as a Eukaryotic Membrane-Binding Bacterial Effector. mSphere 2019; 4:e00354-19. [PMID: 31167949 PMCID: PMC6553557 DOI: 10.1128/msphere.00354-19] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2019] [Accepted: 05/19/2019] [Indexed: 02/07/2023] Open
Abstract
Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis, is one of the most successful human pathogens. One reason for its success is that Mtb can reside within host macrophages, a cell type that normally functions to phagocytose and destroy infectious bacteria. However, Mtb is able to evade macrophage defenses in order to survive for prolonged periods of time. Many intracellular pathogens secrete virulence factors targeting host membranes and organelles to remodel their intracellular environmental niche. We hypothesized that Mtb secreted proteins that target host membranes are vital for Mtb to adapt to and manipulate the host environment for survival. Thus, we characterized 200 secreted proteins from Mtb for their ability to associate with eukaryotic membranes using a unique temperature-sensitive yeast screen and to manipulate host trafficking pathways using a modified inducible secretion screen. We identified five Mtb secreted proteins that both associated with eukaryotic membranes and altered the host secretory pathway. One of these secreted proteins, Mpt64, localized to the endoplasmic reticulum during Mtb infection of murine and human macrophages and impaired the unfolded protein response in macrophages. These data highlight the importance of secreted proteins in Mtb pathogenesis and provide a basis for further investigation into their molecular mechanisms.IMPORTANCE Advances have been made to identify secreted proteins of Mycobacterium tuberculosis during animal infections. These data, combined with transposon screens identifying genes important for M. tuberculosis virulence, have generated a vast resource of potential M. tuberculosis virulence proteins. However, the function of many of these proteins in M. tuberculosis pathogenesis remains elusive. We have integrated three cell biological screens to characterize nearly 200 M. tuberculosis secreted proteins for eukaryotic membrane binding, host subcellular localization, and interactions with host vesicular trafficking. In addition, we observed the localization of one secreted protein, Mpt64, to the endoplasmic reticulum (ER) during M. tuberculosis infection of macrophages. Interestingly, although Mpt64 is exported by the Sec pathway, its delivery into host cells was dependent upon the action of the type VII secretion system. Finally, we observed that Mpt64 impairs the ER-mediated unfolded protein response in macrophages.
Collapse
Affiliation(s)
- Chelsea E Stamm
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Breanna L Pasko
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Sujittra Chaisavaneeyakorn
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Luis H Franco
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Center for Autophagy Research, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Vidhya R Nair
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Bethany A Weigele
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Neal M Alto
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| | - Michael U Shiloh
- Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas, USA
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas, USA
| |
Collapse
|
22
|
Abstract
It is generally regarded that the progression of an infection within host macrophages is the consequence of a failed immune response. However, recent appreciation of macrophage heterogeneity, with respect to both development and metabolism, indicates that the reality is more complex. Different lineages of tissue-resident macrophages respond divergently to microbial, environmental and immunological stimuli. The emerging picture that the developmental origin of macrophages determines their responses to immune stimulation and to infection stresses the importance of in vivo infection models. Recent investigations into the metabolism of infecting microorganisms and host macrophages indicate that their metabolic interface can be a major determinant of pathogen growth or containment. This Review focuses on the integration of data from existing studies, the identification of challenges in generating and interpreting data from ongoing studies and a discussion of the technologies and tools that are required to best address future questions in the field.
Collapse
Affiliation(s)
- David G Russell
- Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY, USA.
| | - Lu Huang
- Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY, USA
| | - Brian C VanderVen
- Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, NY, USA
| |
Collapse
|
23
|
Levanova N, Mattheis C, Carson D, To KN, Jank T, Frankel G, Aktories K, Schroeder GN. The Legionella effector LtpM is a new type of phosphoinositide-activated glucosyltransferase. J Biol Chem 2019; 294:2862-2879. [PMID: 30573678 PMCID: PMC6393602 DOI: 10.1074/jbc.ra118.005952] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2018] [Revised: 12/13/2018] [Indexed: 01/01/2023] Open
Abstract
Legionella pneumophila causes Legionnaires' disease, a severe form of pneumonia. L. pneumophila translocates more than 300 effectors into host cells via its Dot/Icm (Defective in organelle trafficking/Intracellular multiplication) type IV secretion system to enable its replication in target cells. Here, we studied the effector LtpM, which is encoded in a recombination hot spot in L. pneumophila Paris. We show that a C-terminal phosphoinositol 3-phosphate (PI3P)-binding domain, also found in otherwise unrelated effectors, targets LtpM to the Legionella-containing vacuole and to early and late endosomes. LtpM expression in yeast caused cytotoxicity. Sequence comparison and structural homology modeling of the N-terminal domain of LtpM uncovered a remote similarity to the glycosyltransferase (GT) toxin PaTox from the bacterium Photorhabdus asymbiotica; however, instead of the canonical DxD motif of GT-A type glycosyltransferases, essential for enzyme activity and divalent cation coordination, we found that a DxN motif is present in LtpM. Using UDP-glucose as sugar donor, we show that purified LtpM nevertheless exhibits glucohydrolase and autoglucosylation activity in vitro and demonstrate that PI3P binding activates LtpM's glucosyltransferase activity toward protein substrates. Substitution of the aspartate or the asparagine in the DxN motif abolished the activity of LtpM. Moreover, whereas all glycosyltransferase toxins and effectors identified so far depend on the presence of divalent cations, LtpM is active in their absence. Proteins containing LtpM-like GT domains are encoded in the genomes of other L. pneumophila isolates and species, suggesting that LtpM is the first member of a novel family of glycosyltransferase effectors employed to subvert hosts.
Collapse
Affiliation(s)
- Nadezhda Levanova
- From the Institute of Experimental and Clinical Pharmacology and Toxicology, Faculty of Medicine, University of Freiburg, D-79104 Freiburg, Germany
| | - Corinna Mattheis
- the MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London SW7 2AZ, United Kingdom, and
| | - Danielle Carson
- the MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London SW7 2AZ, United Kingdom, and
| | - Ka-Ning To
- the MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London SW7 2AZ, United Kingdom, and
| | - Thomas Jank
- From the Institute of Experimental and Clinical Pharmacology and Toxicology, Faculty of Medicine, University of Freiburg, D-79104 Freiburg, Germany
| | - Gad Frankel
- the MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London SW7 2AZ, United Kingdom, and
| | - Klaus Aktories
- From the Institute of Experimental and Clinical Pharmacology and Toxicology, Faculty of Medicine, University of Freiburg, D-79104 Freiburg, Germany,
| | - Gunnar Neels Schroeder
- the MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College London, London SW7 2AZ, United Kingdom, and
- the Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry, and Biomedical Sciences, Queen's University Belfast, Belfast BT9 7BL, Northern Ireland, United Kingdom
| |
Collapse
|
24
|
Sorting of Phagocytic Cells Infected with Legionella pneumophila. Methods Mol Biol 2019; 1921:179-189. [PMID: 30694492 DOI: 10.1007/978-1-4939-9048-1_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/23/2023]
Abstract
The ability of Legionella pneumophila to colonize host cells and to form a replicative vacuole depends on its ability to counteract the host cell response by secreting more than 300 effectors. The host cell responds to this bacterial invasion with extensive intracellular signaling to counteract the replication of the pathogen. When studying L. pneumophila infection in vitro, only a small proportion of the cell lines or primary cells used to analyze the host response are infected; the study of such a mixed cell population leads to unprecise results. In order to study the multitude of pathogen-induced phenotypic changes occurring in the host cell, the separation of infected from uninfected cells is a top priority. Here we describe a highly efficient FACS-derived protocol to separate cells infected with a L. pneumophila strain encoding a fluorescent protein. Indeed, the highly infected, homogenous cell population obtained after sorting is the best possible starting point for the studies of infection-induced effects.
Collapse
|
25
|
Feldheim YS, Zusman T, Kapach A, Segal G. The single-domain response regulator LerC functions as a connector protein in theLegionella pneumophilaeffectors regulatory network. Mol Microbiol 2018; 110:741-760. [DOI: 10.1111/mmi.14101] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Revised: 07/29/2018] [Accepted: 08/07/2018] [Indexed: 01/10/2023]
Affiliation(s)
- Yaron S. Feldheim
- Department of Molecular Microbiology and Biotechnology, School of Molecular Cell Biology and Biotechnology, George S. Wise Faculty of Life Sciences; Tel-Aviv University; Tel-Aviv Israel
| | - Tal Zusman
- Department of Molecular Microbiology and Biotechnology, School of Molecular Cell Biology and Biotechnology, George S. Wise Faculty of Life Sciences; Tel-Aviv University; Tel-Aviv Israel
| | - Anya Kapach
- Department of Molecular Microbiology and Biotechnology, School of Molecular Cell Biology and Biotechnology, George S. Wise Faculty of Life Sciences; Tel-Aviv University; Tel-Aviv Israel
| | - Gil Segal
- Department of Molecular Microbiology and Biotechnology, School of Molecular Cell Biology and Biotechnology, George S. Wise Faculty of Life Sciences; Tel-Aviv University; Tel-Aviv Israel
| |
Collapse
|
26
|
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.
Collapse
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.
| |
Collapse
|
27
|
Duron O, Doublet P, Vavre F, Bouchon D. The Importance of Revisiting Legionellales Diversity. Trends Parasitol 2018; 34:1027-1037. [PMID: 30322750 DOI: 10.1016/j.pt.2018.09.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Revised: 09/19/2018] [Accepted: 09/24/2018] [Indexed: 12/15/2022]
Abstract
Bacteria of the order Legionellales, such as Legionella pneumophila, the agent of Legionnaires' disease, and Coxiella burnetii, the agent of Q fever, are widely recognized as human pathogens. While our view of the Legionellales is often limited to clinical isolates, ecological surveys are continually uncovering new members of the Legionellales that do not fall into the recognized pathogenic species. Here we emphasize that most of these Legionellales are nonpathogenic forms that have evolved symbiotic lifestyles with nonvertebrate hosts. The diversity of nonpathogenic forms remains, however, largely underexplored. We conjecture that its characterization, once contrasted with the data on pathogenic species, will reveal novel highlights on the mechanisms underlying lifestyle transitions of intracellular bacteria, including the emergence of pathogenesis and mutualism, transmission routes, and host specificity.
Collapse
Affiliation(s)
- Olivier Duron
- Laboratoire Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle (MIVEGEC), Centre National de la Recherche Scientifique (CNRS) - Institut pour la Recherche et le Développement (IRD) - Université de Montpellier (UM), 911 Avenue Agropolis, F-34394 Montpellier, France.
| | - Patricia Doublet
- CIRI, Centre International de Recherche en Infectiologie, INSERM, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, École Normale Supérieure de Lyon, Université Lyon, F-69100 Villeurbanne, France
| | - Fabrice Vavre
- Univ Lyon, Université Lyon 1, CNRS, Laboratoire de Biométrie et Biologie Evolutive UMR5558, 43 Boulevard du 11 novembre 1918, F-69622 Villeurbanne, France
| | - Didier Bouchon
- Université de Poitiers, Laboratoire Ecologie et Biologie des Interactions - UMR CNRS 7267, F-86073 Poitiers, France
| |
Collapse
|
28
|
Characterization of the glucosyltransferase activity of Legionella pneumophila effector SetA. Naunyn Schmiedebergs Arch Pharmacol 2018; 392:69-79. [PMID: 30225797 DOI: 10.1007/s00210-018-1562-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Accepted: 08/30/2018] [Indexed: 12/13/2022]
Abstract
Legionella pneumophila glucosyltransferase SetA, which is introduced into target cells by a type IV secretion system, affects the intracellular traffic of host cells. Here, we characterized the enzyme activity of the Legionella effector. We report that Asp118 and Arg121 of SetA are essential for glucohydrolase and glucotransferase activities. Exchange of Trp36 to alanine reduced the enzyme activity of SetA. All three amino acids were crucial for the cytotoxic effects of SetA in yeast. We observed that phosphatidylinositol-3-phosphate (PI3P) increased the glucosyltransferase activity of SetA severalfold, while the glucohydrolase activity was not affected. In the presence of PI3P, we observed the glucosylation of actin, vimentin and the chaperonin CCT5 in the cytosolic fraction of target cells. Studies on the functional consequences of glucosylation of skeletal muscle α-actin in vitro revealed inhibition of actin polymerization by glucosylation.
Collapse
|
29
|
Quantitative Imaging Flow Cytometry of Legionella-Infected Dictyostelium Amoebae Reveals the Impact of Retrograde Trafficking on Pathogen Vacuole Composition. Appl Environ Microbiol 2018; 84:AEM.00158-18. [PMID: 29602783 DOI: 10.1128/aem.00158-18] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Accepted: 03/27/2018] [Indexed: 01/15/2023] Open
Abstract
The ubiquitous environmental bacterium Legionella pneumophila survives and replicates within amoebae and human macrophages by forming a Legionella-containing vacuole (LCV). In an intricate process governed by the bacterial Icm/Dot type IV secretion system and a plethora of effector proteins, the nascent LCV interferes with a number of intracellular trafficking pathways, including retrograde transport from endosomes to the Golgi apparatus. Conserved retrograde trafficking components, such as the retromer coat complex or the phosphoinositide (PI) 5-phosphatase D. discoideum 5-phosphatase 4 (Dd5P4)/oculocerebrorenal syndrome of Lowe (OCRL), restrict intracellular replication of L. pneumophila by an unknown mechanism. Here, we established an imaging flow cytometry (IFC) approach to assess in a rapid, unbiased, and large-scale quantitative manner the role of retrograde-linked PI metabolism and actin dynamics in the LCV composition. Exploiting Dictyostelium discoideum genetics, we found that Dd5P4 modulates the acquisition of fluorescently labeled LCV markers, such as calnexin, the small GTPase Rab1 (but not Rab7 and Rab8), and retrograde trafficking components (Vps5, Vps26, Vps35). The actin-nucleating protein and retromer interactor WASH (Wiskott-Aldrich syndrome protein [WASP] and suppressor of cAMP receptor [SCAR] homologue) promotes the accumulation of Rab1 and Rab8 on LCVs. Collectively, our findings validate IFC for the quantitative and unbiased analysis of the pathogen vacuole composition and reveal the impact of retrograde-linked PI metabolism and actin dynamics on the LCV composition. The IFC approach employed here can be adapted for a molecular analysis of the pathogen vacuole composition of other amoeba-resistant pathogens.IMPORTANCELegionella pneumophila is an amoeba-resistant environmental bacterium which can cause a life-threatening pneumonia termed Legionnaires' disease. In order to replicate intracellularly, the opportunistic pathogen forms a protective compartment, the Legionella-containing vacuole (LCV). An in-depth analysis of the LCV composition and the complex process of pathogen vacuole formation is crucial for understanding the virulence of L. pneumophila Here, we established an imaging flow cytometry (IFC) approach to assess in a rapid, unbiased, and quantitative manner the accumulation of fluorescently labeled markers and probes on LCVs. Using IFC and L. pneumophila-infected Dictyostelium discoideum or defined mutant amoebae, a role for phosphoinositide (PI) metabolism, retrograde trafficking, and the actin cytoskeleton in the LCV composition was revealed. In principle, the powerful IFC approach can be used to analyze the molecular composition of any cellular compartment harboring bacterial pathogens.
Collapse
|
30
|
Schuhmacher MK, Rolando M, Bröhm A, Weirich S, Kudithipudi S, Buchrieser C, Jeltsch A. The Legionella pneumophila Methyltransferase RomA Methylates Also Non-histone Proteins during Infection. J Mol Biol 2018; 430:1912-1925. [PMID: 29733858 DOI: 10.1016/j.jmb.2018.04.032] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Revised: 04/19/2018] [Accepted: 04/23/2018] [Indexed: 12/14/2022]
Abstract
RomA is a SET-domain containing protein lysine methyltransferase encoded by the Gram-negative bacterium Legionella pneumophila. It is exported into human host cells during infection and has been previously shown to methylate histone H3 at lysine 14 [Rolando et al. (2013), Cell Host Microbe, 13, 395-405]. Here, we investigated the substrate specificity of RomA on peptide arrays showing that it mainly recognizes a G-K-X-(PA) sequence embedded in a basic amino acid sequence context. Based on the specificity profile, we searched for possible additional RomA substrates in the human proteome and identified 34 novel peptide substrates. For nine of these, the corresponding full-length protein or protein domains could be cloned and purified. Using radioactive and antibody-based methylation assays, we showed that seven of them are methylated by RomA, four of them strongly, one moderately, and two weakly. Mutagenesis confirmed for the seven methylated proteins that methylation occurs at target lysine residues fitting to the specificity profile. Methylation of one novel substrate (AROS) was investigated in HEK293 cells overexpressing RomA and during infection with L. pneumophila. Methylation could be detected in both conditions, confirming that RomA methylates non-histone proteins in human cells. Our data show that the bacterial methyltransferase RomA methylates also human non-histone proteins suggesting a multifaceted role in the infection process.
Collapse
Affiliation(s)
- Maren Kirstin Schuhmacher
- Department of Biochemistry, Institute of Biochemistry and Technical Biochemistry, University Stuttgart, Allmandring 31, 70569 Stuttgart, Germany
| | - Monica Rolando
- Institut Pasteur, Biologie des Bactéries Intracellulaires, 75724 Paris, France; CNRS UMR 3525, 75724 Paris, France
| | - Alexander Bröhm
- Department of Biochemistry, Institute of Biochemistry and Technical Biochemistry, University Stuttgart, Allmandring 31, 70569 Stuttgart, Germany
| | - Sara Weirich
- Department of Biochemistry, Institute of Biochemistry and Technical Biochemistry, University Stuttgart, Allmandring 31, 70569 Stuttgart, Germany
| | - Srikanth Kudithipudi
- Department of Biochemistry, Institute of Biochemistry and Technical Biochemistry, University Stuttgart, Allmandring 31, 70569 Stuttgart, Germany
| | - Carmen Buchrieser
- Institut Pasteur, Biologie des Bactéries Intracellulaires, 75724 Paris, France; CNRS UMR 3525, 75724 Paris, France
| | - Albert Jeltsch
- Department of Biochemistry, Institute of Biochemistry and Technical Biochemistry, University Stuttgart, Allmandring 31, 70569 Stuttgart, Germany.
| |
Collapse
|
31
|
Prashar A, Ortiz ME, Lucarelli S, Barker E, Tabatabeiyazdi Z, Shamoun F, Raju D, Antonescu C, Guyard C, Terebiznik MR. Small Rho GTPases and the Effector VipA Mediate the Invasion of Epithelial Cells by Filamentous Legionella pneumophila. Front Cell Infect Microbiol 2018; 8:133. [PMID: 29774203 PMCID: PMC5943596 DOI: 10.3389/fcimb.2018.00133] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2017] [Accepted: 04/17/2018] [Indexed: 12/13/2022] Open
Abstract
Legionella pneumophila (Lp) exhibits different morphologies with varying degrees of virulence. Despite their detection in environmental sources of outbreaks and in respiratory tract secretions and lung autopsies from patients, the filamentous morphotype of Lp remains poorly studied. We previously demonstrated that filamentous Lp invades lung epithelial cells (LECs) and replicates intracellularly in a Legionella containing vacuole. Filamentous Lp activates β1integrin and E-cadherin receptors at the surface of LECs leading to the formation of actin-rich cell membrane structures we termed hooks and membrane wraps. These structures entrap segments of an Lp filament on host cell surface and mediate bacterial internalization. Here we investigated the molecular mechanisms responsible for the actin rearrangements needed for the formation and elongation of these membrane wraps and bacterial internalization. We combined genetic and pharmacological approaches to assess the contribution of signaling downstream of β1integrin and E-cadherin receptors, and Lp Dot/Icm secretion system- translocated effectors toward the invasion process. Our studies demonstrate a multi-stage mechanism of LEC invasion by filamentous Lp. Bacterial attachment to host cells depends on signaling downstream of β1integrin and E-cadherin activation, leading to Rho GTPases-dependent activation of cellular actin nucleating proteins, Arp2/3 and mDia. This mediates the formation of primordial membrane wraps that entrap the filamentous bacteria on the cell surface. Following this, in a second phase of the invasion process the Dot/Icm translocated effector VipA mediates rapid membrane wrap elongation, leading to the engulfment of the filamentous bacteria by the LECs. Our findings provide the first description of Rho GTPases and a Dot/Icm effector VipA regulating the actin dynamics needed for the invasion of epithelial cells by Lp.
Collapse
Affiliation(s)
- Akriti Prashar
- Department of Biological Sciences, University of Toronto at Scarborough, Scarborough, ON, Canada.,Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada
| | - María Eugenia Ortiz
- Department of Biological Sciences, University of Toronto at Scarborough, Scarborough, ON, Canada
| | - Stefanie Lucarelli
- Department of Chemistry and Biology, Ryerson University, Toronto, ON, Canada
| | - Elizabeth Barker
- Department of Biological Sciences, University of Toronto at Scarborough, Scarborough, ON, Canada.,Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada
| | - Zohreh Tabatabeiyazdi
- Department of Biological Sciences, University of Toronto at Scarborough, Scarborough, ON, Canada.,Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada
| | - Feras Shamoun
- Department of Biological Sciences, University of Toronto at Scarborough, Scarborough, ON, Canada
| | - Deepa Raju
- Department of Biological Sciences, University of Toronto at Scarborough, Scarborough, ON, Canada
| | - Costin Antonescu
- Department of Chemistry and Biology, Ryerson University, Toronto, ON, Canada
| | - Cyril Guyard
- Bioaster, Lyon, France.,Molecular Microbiology, Public Health Ontario, Toronto, ON, Canada
| | - Mauricio R Terebiznik
- Department of Biological Sciences, University of Toronto at Scarborough, Scarborough, ON, Canada.,Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada
| |
Collapse
|
32
|
Kuo CJ, Hansen M, Troemel E. Autophagy and innate immunity: Insights from invertebrate model organisms. Autophagy 2018; 14:233-242. [PMID: 29130360 DOI: 10.1080/15548627.2017.1389824] [Citation(s) in RCA: 95] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Macroautophagy/autophagy is a fundamental intracellular degradation process with multiple roles in immunity, including direct elimination of intracellular microorganisms via 'xenophagy.' In this review, we summarize studies from the fruit fly Drosophila melanogaster and the nematode Caenorhabditis elegans that highlight the roles of autophagy in innate immune responses to viral, bacterial, and fungal pathogens. Research from these genetically tractable invertebrates has uncovered several conserved immunological paradigms, such as direct targeting of intracellular pathogens by xenophagy and regulation of autophagy by pattern recognition receptors in D. melanogaster. Although C. elegans has no known pattern recognition receptors, this organism has been particularly useful in understanding many aspects of innate immunity. Indeed, work in C. elegans was the first to show xenophagic targeting of microsporidia, a fungal pathogen that infects all animals, and to identify TFEB/HLH-30, a helix-loop-helix transcription factor, as an evolutionarily conserved regulator of autophagy gene expression and host tolerance. Studies in C. elegans have also highlighted the more recently appreciated relationship between autophagy and tolerance to extracellular pathogens. Studies of simple, short-lived invertebrates such as flies and worms will continue to provide valuable insights into the molecular mechanisms by which autophagy and immunity pathways intersect and their contribution to organismal survival. Abbreviations Atg autophagy related BECN1 Beclin 1 CALCOCO2 calcium binding and coiled-coil domain 2 Cry5B crystal toxin 5B Daf abnormal dauer formation DKF-1 D kinase family-1 EPG-7 Ectopic P Granules-7 FuDR fluorodeoxyuridine GFP green fluorescent protein HLH-30 Helix Loop Helix-30 Imd immune deficiency ins-18 INSulin related-18; LET-363, LEThal-363 lgg-1 LC3, GABARAP and GATE-16 family-1 MAPK mitogen-activated protein kinase MATH the meprin and TRAF homology MTOR mechanistic target of rapamycin NBR1 neighbor of BRCA1 gene 1 NFKB nuclear factor of kappa light polypeptide gene enhancer in B cells NOD nucleotide-binding oligomerization domain containing OPTN optineurin PAMPs pathogen-associated molecular patterns Park2 Parkinson disease (autosomal recessive, juvenile) 2, parkin pdr-1 Parkinson disease related PFTs pore-forming toxins PGRP peptidoglycan-recognition proteins PIK3C3 phosphatidylinositol 3- kinase catalytic subunit type 3 pink-1 PINK (PTEN-I induced kinase) homolog PRKD protein kinase D; PLC, phospholipase C PRKN parkin RBR E3 ubiquitin protein ligase PRRs pattern-recognition receptors PtdIns3P phosphatidylinositol-3-phosphate rab-5 RAB family-5 RB1CC1 RB1-inducible coiled-coil 1 RNAi RNA interference sqst SeQueSTosome related SQSTM1 sequestosome 1 TBK1 TANK-binding kinase 1 TFEB transcription factor EB TGFB/TGF-β transforming growth factor beta TLRs toll-like receptors unc-51 UNCoordinated-51 VPS vacuolar protein sorting; VSV, vesicular stomatitis virus VSV-G VSV surface glycoprotein G Wipi2 WD repeat domain, phosphoinositide interacting 2.
Collapse
Affiliation(s)
- Cheng-Ju Kuo
- a Division of Biological Sciences , University of California , San Diego, La Jolla , CA , USA.,b Institute of Basic Medical Sciences , College of Medicine , National Cheng Kung University , Tainan , Taiwan
| | - Malene Hansen
- c Sanford Burnham Prebys Medical Discovery Institute, Program of Development, Aging and Regeneration , La Jolla , CA , USA
| | - Emily Troemel
- a Division of Biological Sciences , University of California , San Diego, La Jolla , CA , USA
| |
Collapse
|
33
|
Hiller M, Lang C, Michel W, Flieger A. Secreted phospholipases of the lung pathogen Legionella pneumophila. Int J Med Microbiol 2017; 308:168-175. [PMID: 29108710 DOI: 10.1016/j.ijmm.2017.10.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2017] [Revised: 10/06/2017] [Accepted: 10/22/2017] [Indexed: 11/28/2022] Open
Abstract
Legionella pneumophila is an intracellular pathogen and the main causative agent of Legionnaires' disease, a potentially fatal pneumonia. The bacteria infect both mammalian cells and environmental hosts, such as amoeba. Inside host cells, the bacteria withstand the multifaceted defenses of the phagocyte and replicate within a unique membrane-bound compartment, the Legionella-containing vacuole (LCV). For establishment and maintenance of the infection, L. pneumophila secretes many proteins including effector proteins by means of different secretion systems and outer membrane vesicles. Among these are a large variety of lipolytic enzymes which possess phospholipase/lysophospholipase and/or glycerophospholipid:cholesterol acyltransferase activities. Secreted lipolytic activities may contribute to bacterial virulence, for example via modification of eukaryotic membranes, such as the LCV. In this review, we describe the secretion systems of L. pneumophila, introduce the classification of phospholipases, and summarize the state of the art on secreted L. pneumophila phospholipases. We especially highlight those enzymes secreted via the type II secretion system Lsp, via the type IVB secretion system Dot/Icm, via outer membrane vesicles, and such where the mode of secretion has not yet been defined. We also give an overview on the complexity of their activities, activation mechanisms, localization, growth-phase dependent abundance, and their role in infection.
Collapse
Affiliation(s)
- Miriam Hiller
- Division of Enteropathogenic Bacteria and Legionella, Robert Koch-Institute, Burgstraße 37, 38855 Wernigerode, Germany
| | - Christina Lang
- Division of Enteropathogenic Bacteria and Legionella, Robert Koch-Institute, Burgstraße 37, 38855 Wernigerode, Germany
| | - Wiebke Michel
- Division of Enteropathogenic Bacteria and Legionella, Robert Koch-Institute, Burgstraße 37, 38855 Wernigerode, Germany
| | - Antje Flieger
- Division of Enteropathogenic Bacteria and Legionella, Robert Koch-Institute, Burgstraße 37, 38855 Wernigerode, Germany.
| |
Collapse
|
34
|
Gradowski M, Pawłowski K. The Legionella pneumophila effector Lpg1137 is a homologue of mitochondrial SLC25 carrier proteins, not of known serine proteases. PeerJ 2017; 5:e3849. [PMID: 28966893 PMCID: PMC5621508 DOI: 10.7717/peerj.3849] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Accepted: 09/01/2017] [Indexed: 01/08/2023] Open
Abstract
Many bacterial effector proteins that are delivered to host cells during infection are enzymes targeting host cell signalling. Recently, Legionella pneumophila effector Lpg1137 was experimentally characterised as a serine protease that cleaves human syntaxin 17. We present strong bioinformatic evidence that Lpg1137 is a homologue of mitochondrial carrier proteins and is not related to known serine proteases. We also discuss how this finding can be reconciled with the apparently contradictory experimental results.
Collapse
Affiliation(s)
- Marcin Gradowski
- Department of Experimental Design and Bioinformatics, Faculty of Agriculture and Biology, Warsaw University of Life Sciences, Warszawa, Poland
| | - Krzysztof Pawłowski
- Department of Experimental Design and Bioinformatics, Faculty of Agriculture and Biology, Warsaw University of Life Sciences, Warszawa, Poland.,Department of Translational Medicine, Clinical Sciences, Lund University, Lund, Sweden
| |
Collapse
|
35
|
Eshraghi A, Kim J, Walls AC, Ledvina HE, Miller CN, Ramsey KM, Whitney JC, Radey MC, Peterson SB, Ruhland BR, Tran BQ, Goo YA, Goodlett DR, Dove SL, Celli J, Veesler D, Mougous JD. Secreted Effectors Encoded within and outside of the Francisella Pathogenicity Island Promote Intramacrophage Growth. Cell Host Microbe 2017; 20:573-583. [PMID: 27832588 PMCID: PMC5384264 DOI: 10.1016/j.chom.2016.10.008] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2016] [Revised: 09/18/2016] [Accepted: 10/13/2016] [Indexed: 01/10/2023]
Abstract
The intracellular bacterial pathogen Francisella tularensis causes tularemia, a zoonosis that can be fatal. The type VI secretion system (T6SS) encoded by the Francisella pathogenicity island (FPI) is critical for the virulence of this organism. Existing studies suggest that the complete repertoire of T6SS effectors delivered to host cells is encoded by the FPI. Using a proteome-wide approach, we discovered that the FPI-encoded T6SS exports at least three effectors encoded outside of the island. These proteins share features with virulence determinants of other pathogens, and we provide evidence that they can contribute to intramacrophage growth. The remaining proteins that we identified are encoded within the FPI. Two of these FPI-encoded proteins constitute effectors, whereas the others form a unique complex required for core function of the T6SS apparatus. The discovery of secreted effectors mediating interactions between Francisella and its host significantly advances our understanding of the pathogenesis of this organism.
Collapse
Affiliation(s)
- Aria Eshraghi
- Department of Microbiology, School of Medicine, University of Washington, Seattle, WA 98195, USA
| | - Jungyun Kim
- Department of Microbiology, School of Medicine, University of Washington, Seattle, WA 98195, USA
| | - Alexandra C Walls
- Department of Biochemistry, School of Medicine, University of Washington, Seattle, WA 98195, USA
| | - Hannah E Ledvina
- Department of Microbiology, School of Medicine, University of Washington, Seattle, WA 98195, USA
| | - Cheryl N Miller
- Paul G. Allen School for Global Animal Health, Washington State University, Pullman, WA 99164, USA
| | - Kathryn M Ramsey
- Division of Infectious Diseases, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - John C Whitney
- Department of Microbiology, School of Medicine, University of Washington, Seattle, WA 98195, USA
| | - Matthew C Radey
- Department of Microbiology, School of Medicine, University of Washington, Seattle, WA 98195, USA
| | - S Brook Peterson
- Department of Microbiology, School of Medicine, University of Washington, Seattle, WA 98195, USA
| | - Brittany R Ruhland
- Department of Microbiology, School of Medicine, University of Washington, Seattle, WA 98195, USA
| | - Bao Q Tran
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, MD 21201, USA
| | - Young Ah Goo
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, MD 21201, USA
| | - David R Goodlett
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, MD 21201, USA
| | - Simon L Dove
- Division of Infectious Diseases, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Jean Celli
- Paul G. Allen School for Global Animal Health, Washington State University, Pullman, WA 99164, USA
| | - David Veesler
- Department of Biochemistry, School of Medicine, University of Washington, Seattle, WA 98195, USA
| | - Joseph D Mougous
- Department of Microbiology, School of Medicine, University of Washington, Seattle, WA 98195, USA; Howard Hughes Medical Institute, School of Medicine, University of Washington, Seattle, WA 98195, USA.
| |
Collapse
|
36
|
Puvar K, Zhou Y, Qiu J, Luo ZQ, Wirth MJ, Das C. Ubiquitin Chains Modified by the Bacterial Ligase SdeA Are Protected from Deubiquitinase Hydrolysis. Biochemistry 2017; 56:4762-4766. [PMID: 28809541 DOI: 10.1021/acs.biochem.7b00664] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The SidE family of Legionella pneumophila effectors is a unique group of ubiquitin-modifying enzymes. Along with catalyzing NAD+-dependent ubiquitination of certain host proteins independent of the canonical E1/E2/E3 pathway, they have also been shown to produce phosphoribosylated free ubiquitin. This modified ubiquitin product is incompatible with conventional E1/E2/E3 ubiquitination processes, with the potential to lock down various cellular functions that are dependent on ubiquitin signaling. Here, we show that in addition to free ubiquitin, Lys63-, Lys48-, Lys11-, and Met1-linked diubiquitin chains are also modified by SdeA in a similar fashion. Both the proximal and distal ubiquitin moieties are targeted in the phosphoribosylation reaction. Furthermore, this renders the ubiquitin chains unable to be processed by a variety of deubiquitinating enzymes. These observations broaden the scope of SdeA's modulatory functions during Legionella infection.
Collapse
Affiliation(s)
- Kedar Puvar
- Department of Chemistry, Purdue University , 560 Oval Drive, West Lafayette, Indiana 47906, United States
| | - Yiyang Zhou
- Department of Chemistry, Purdue University , 560 Oval Drive, West Lafayette, Indiana 47906, United States
| | - Jiazhang Qiu
- Purdue Institute of Immunology, Inflammation, and Infectious Diseases and Department of Biological Sciences, Purdue University , 915 West State Street, West Lafayette, Indiana 47906, United States.,Key Laboratory of Zoonosis, Ministry of Education, Institute of Zoonosis, College of Veterinary Medicine, Jilin University , Xi'an Road 5333, Changchun, Jilin 130062, China
| | - Zhao-Qing Luo
- Purdue Institute of Immunology, Inflammation, and Infectious Diseases and Department of Biological Sciences, Purdue University , 915 West State Street, West Lafayette, Indiana 47906, United States
| | - Mary J Wirth
- Department of Chemistry, Purdue University , 560 Oval Drive, West Lafayette, Indiana 47906, United States
| | - Chittaranjan Das
- Department of Chemistry, Purdue University , 560 Oval Drive, West Lafayette, Indiana 47906, United States
| |
Collapse
|
37
|
Jung AL, Herkt CE, Schulz C, Bolte K, Seidel K, Scheller N, Sittka-Stark A, Bertrams W, Schmeck B. Legionella pneumophila infection activates bystander cells differentially by bacterial and host cell vesicles. Sci Rep 2017; 7:6301. [PMID: 28740179 PMCID: PMC5524687 DOI: 10.1038/s41598-017-06443-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Accepted: 06/13/2017] [Indexed: 01/08/2023] Open
Abstract
Extracellular vesicles from eukaryotic cells and outer membrane vesicles (OMVs) released from gram-negative bacteria have been described as mediators of pathogen-host interaction and intercellular communication. Legionella pneumophila (L. pneumophila) is a causative agent of severe pneumonia. The differential effect of bacterial and host cell vesicles in L. pneumophila infection is unknown so far. We infected THP-1-derived or primary human macrophages with L. pneumophila and isolated supernatant vesicles by differential centrifugation. We observed an increase of exosomes in the 100 k pellet by nanoparticle tracking analysis, electron microscopy, and protein markers. This fraction additionally contained Legionella LPS, indicating also the presence of OMVs. In contrast, vesicles in the 16 k pellet, representing microparticles, decreased during infection. The 100 k vesicle fraction activated uninfected primary human alveolar epithelial cells, A549 cells, and THP-1 cells. Epithelial cell activation was reduced by exosome depletion (anti-CD63, or GW4869), or blocking of IL-1β in the supernatant. In contrast, the response of THP-1 cells to vesicles was reduced by a TLR2-neutralizing antibody, UV-inactivation of bacteria, or – partially – RNase-treatment of vesicles. Taken together, we found that during L. pneumophila infection, neighbouring epithelial cells were predominantly activated by exosomes and cytokines, whereas myeloid cells were activated by bacterial OMVs.
Collapse
Affiliation(s)
- Anna Lena Jung
- Institute for Lung Research, German Center for Lung Research, Universities of Giessen and Marburg Lung Centre, Philipps-University Marburg, 35043, Marburg, Germany
| | - Christina Elena Herkt
- Institute for Lung Research, German Center for Lung Research, Universities of Giessen and Marburg Lung Centre, Philipps-University Marburg, 35043, Marburg, Germany
| | - Christine Schulz
- Institute for Lung Research, German Center for Lung Research, Universities of Giessen and Marburg Lung Centre, Philipps-University Marburg, 35043, Marburg, Germany
| | - Kathrin Bolte
- Department for Cell Biology, Philipps-University Marburg, 35043, Marburg, Germany
| | - Kerstin Seidel
- Institute for Lung Research, German Center for Lung Research, Universities of Giessen and Marburg Lung Centre, Philipps-University Marburg, 35043, Marburg, Germany
| | - Nicoletta Scheller
- Institute for Lung Research, German Center for Lung Research, Universities of Giessen and Marburg Lung Centre, Philipps-University Marburg, 35043, Marburg, Germany
| | - Alexandra Sittka-Stark
- Institute for Lung Research, German Center for Lung Research, Universities of Giessen and Marburg Lung Centre, Philipps-University Marburg, 35043, Marburg, Germany.,Labor Berlin Services GmbH, 13353, Berlin, Germany
| | - Wilhelm Bertrams
- Institute for Lung Research, German Center for Lung Research, Universities of Giessen and Marburg Lung Centre, Philipps-University Marburg, 35043, Marburg, Germany
| | - Bernd Schmeck
- Institute for Lung Research, German Center for Lung Research, Universities of Giessen and Marburg Lung Centre, Philipps-University Marburg, 35043, Marburg, Germany. .,Department of Medicine, Pulmonary and Critical Care Medicine, University Medical Center Marburg, Philipps-University, 35043, Marburg, Germany.
| |
Collapse
|
38
|
Divergent evolution of Di-lysine ER retention vs. farnesylation motif-mediated anchoring of the AnkB virulence effector to the Legionella-containing vacuolar membrane. Sci Rep 2017; 7:5123. [PMID: 28698607 PMCID: PMC5506055 DOI: 10.1038/s41598-017-05211-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Accepted: 05/24/2017] [Indexed: 11/26/2022] Open
Abstract
Within macrophages and amoeba, the Legionella-containing vacuole (LCV) membrane is derived from the ER. The bona fide F-box AnkB effector protein of L. pneumophila strain AA100/130b is anchored to the cytosolic side of the LCV membrane through host-mediated farnesylation of its C-terminal eukaryotic “CaaX” motif. Here we show that the AnkB homologue of the Paris strain has a frame shift mutation that led to a loss of the CaaX motif and a concurrent generation of a unique C-terminal KNKYAP motif, which resembles the eukaryotic di-lysine ER-retention motif (KxKxx). Our phylogenetic analyses indicate that environmental isolates of L. pneumophila have a potential positive selection for the ER-retention KNKYAP motif. The AnkB-Paris effector is localized to the LCV membrane most likely through the ER-retention motif. Its ectopic expression in HEK293T cells localizes it to the perinuclear ER region and it trans-rescues the ankB mutant of strain AA100/130b in intra-vacuolar replication. The di-lysine ER retention motif of AnkB-Paris is indispensable for function; most likely as an ER retention motif that enables anchoring to the ER-derived LCV membrane. Our findings show divergent evolution of the ankB allele in exploiting either host farnesylation or the ER retention motif to be anchored into the LCV membrane.
Collapse
|
39
|
Polar delivery of Legionella type IV secretion system substrates is essential for virulence. Proc Natl Acad Sci U S A 2017; 114:8077-8082. [PMID: 28696299 DOI: 10.1073/pnas.1621438114] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
A recurrent emerging theme is the targeting of proteins to subcellular microdomains within bacterial cells, particularly to the poles. In most cases, it has been assumed that this localization is critical to the protein's function. Legionella pneumophila uses a type IVB secretion system (T4BSS) to export a large number of protein substrates into the cytoplasm of host cells. Here we show that the Legionella export apparatus is localized to the bacterial poles, as is consistent with many T4SS substrates being retained on the phagosomal membrane adjacent to the poles of the bacterium. More significantly, we were able to demonstrate that polar secretion of substrates is critically required for Legionella's alteration of the host endocytic pathway, an activity required for this pathogen's virulence.
Collapse
|
40
|
Abstract
Intracellular bacterial pathogens survive and replicate within specialized eukaryotic cell organelles. To establish their intracellular niches these pathogens have adopted sophisticated strategies to control intracellular membrane trafficking. Since Rab-family GTPases are critical regulators of endocytic and secretory membrane trafficking events, many intracellular pathogens have evolved specific mechanisms to modulate or hijack Rab GTPases dynamics and trafficking functions. One such strategy is the delivery of bacterial effectors through specialized machines to specifically target Rab GTPases. Some of these effectors functionally mimic host proteins that regulate the Rab GTP cycle, while others regulate Rabs proteins through their post-translation modifications or proteolysis. In this review, we examine how the localization and function of Rab-family GTPases are altered during infection with 3 well-studied intracellular bacterial pathogens, Mycobacterium tuberculosis, Salmonella enterica and Legionella pneumophila. We also discuss recent findings about specific mechanisms by which these intracellular pathogens target this protein family.
Collapse
Affiliation(s)
- Stefania Spanò
- a Institute of Medical Sciences, University of Aberdeen , Foresterhill , Aberdeen , UK
| | - Jorge E Galán
- b Department of Microbial Pathogenesis , Yale University School of Medicine , New Haven , CT , USA
| |
Collapse
|
41
|
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.
Collapse
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
| |
Collapse
|
42
|
Liss V, Swart AL, Kehl A, Hermanns N, Zhang Y, Chikkaballi D, Böhles N, Deiwick J, Hensel M. Salmonella enterica Remodels the Host Cell Endosomal System for Efficient Intravacuolar Nutrition. Cell Host Microbe 2017; 21:390-402. [DOI: 10.1016/j.chom.2017.02.005] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2016] [Revised: 10/04/2016] [Accepted: 02/02/2017] [Indexed: 01/09/2023]
|
43
|
Galectin-3 directs antimicrobial guanylate binding proteins to vacuoles furnished with bacterial secretion systems. Proc Natl Acad Sci U S A 2017; 114:E1698-E1706. [PMID: 28193861 DOI: 10.1073/pnas.1615771114] [Citation(s) in RCA: 98] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Many invasive bacteria establish pathogen-containing vacuoles (PVs) as intracellular niches for microbial growth. Immunity to these infections is dependent on the ability of host cells to recognize PVs as targets for host defense. The delivery of several host defense proteins to PVs is controlled by IFN-inducible guanylate binding proteins (GBPs), which themselves dock to PVs through poorly characterized mechanisms. Here, we demonstrate that GBPs detect the presence of bacterial protein secretion systems as "patterns of pathogenesis" associated with PVs. We report that the delivery of GBP2 to Legionella-containing vacuoles is dependent on the bacterial Dot/Icm secretion system, whereas the delivery of GBP2 to Yersinia-containing vacuoles (YCVs) requires hypersecretion of Yersinia translocon proteins. We show that the presence of bacterial secretion systems directs cytosolic carbohydrate-binding protein Galectin-3 to PVs and that the delivery of GBP1 and GBP2 to Legionella-containing vacuoles or YCVs is substantially diminished in Galectin-3-deficient cells. Our results illustrate that insertion of bacterial secretion systems into PV membranes stimulates Galectin-3-dependent recruitment of antimicrobial GBPs to PVs as part of a coordinated host defense program.
Collapse
|
44
|
Urbanus ML, Quaile AT, Stogios PJ, Morar M, Rao C, Di Leo R, Evdokimova E, Lam M, Oatway C, Cuff ME, Osipiuk J, Michalska K, Nocek BP, Taipale M, Savchenko A, Ensminger AW. Diverse mechanisms of metaeffector activity in an intracellular bacterial pathogen, Legionella pneumophila. Mol Syst Biol 2016; 12:893. [PMID: 27986836 PMCID: PMC5199130 DOI: 10.15252/msb.20167381] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Pathogens deliver complex arsenals of translocated effector proteins to host cells during infection, but the extent to which these proteins are regulated once inside the eukaryotic cell remains poorly defined. Among all bacterial pathogens, Legionella pneumophila maintains the largest known set of translocated substrates, delivering over 300 proteins to the host cell via its Type IVB, Icm/Dot translocation system. Backed by a few notable examples of effector–effector regulation in L. pneumophila, we sought to define the extent of this phenomenon through a systematic analysis of effector–effector functional interaction. We used Saccharomyces cerevisiae, an established proxy for the eukaryotic host, to query > 108,000 pairwise genetic interactions between two compatible expression libraries of ~330 L. pneumophila‐translocated substrates. While capturing all known examples of effector–effector suppression, we identify fourteen novel translocated substrates that suppress the activity of other bacterial effectors and one pair with synergistic activities. In at least nine instances, this regulation is direct—a hallmark of an emerging class of proteins called metaeffectors, or “effectors of effectors”. Through detailed structural and functional analysis, we show that metaeffector activity derives from a diverse range of mechanisms, shapes evolution, and can be used to reveal important aspects of each cognate effector's function. Metaeffectors, along with other, indirect, forms of effector–effector modulation, may be a common feature of many intracellular pathogens—with unrealized potential to inform our understanding of how pathogens regulate their interactions with the host cell.
Collapse
Affiliation(s)
- Malene L Urbanus
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada
| | - Andrew T Quaile
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, ON, Canada
| | - Peter J Stogios
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, ON, Canada
| | - Mariya Morar
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, ON, Canada
| | - Chitong Rao
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Rosa Di Leo
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, ON, Canada
| | - Elena Evdokimova
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, ON, Canada
| | - Mandy Lam
- Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON, Canada
| | - Christina Oatway
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Marianne E Cuff
- Biosciences Division, Argonne National Laboratory, Structural Biology Center, Lemont, IL, USA.,Midwest Center for Structural Genomics, Lemont IL, USA
| | - Jerzy Osipiuk
- Biosciences Division, Argonne National Laboratory, Structural Biology Center, Lemont, IL, USA.,Midwest Center for Structural Genomics, Lemont IL, USA
| | - Karolina Michalska
- Biosciences Division, Argonne National Laboratory, Structural Biology Center, Lemont, IL, USA.,Midwest Center for Structural Genomics, Lemont IL, USA
| | - Boguslaw P Nocek
- Biosciences Division, Argonne National Laboratory, Structural Biology Center, Lemont, IL, USA.,Midwest Center for Structural Genomics, Lemont IL, USA
| | - Mikko Taipale
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada.,Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, ON, Canada
| | - Alexei Savchenko
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, ON, Canada .,Midwest Center for Structural Genomics, Lemont IL, USA
| | - Alexander W Ensminger
- Department of Biochemistry, University of Toronto, Toronto, ON, Canada .,Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada.,Public Health Ontario, Toronto, ON, Canada
| |
Collapse
|
45
|
Marchesini MI, Morrone Seijo SM, Guaimas FF, Comerci DJ. A T4SS Effector Targets Host Cell Alpha-Enolase Contributing to Brucella abortus Intracellular Lifestyle. Front Cell Infect Microbiol 2016; 6:153. [PMID: 27900285 PMCID: PMC5110553 DOI: 10.3389/fcimb.2016.00153] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2016] [Accepted: 11/01/2016] [Indexed: 01/18/2023] Open
Abstract
Brucella abortus, the causative agent of bovine brucellosis, invades and replicates within cells inside a membrane-bound compartment known as the Brucella containing vacuole (BCV). After trafficking along the endocytic and secretory pathways, BCVs mature into endoplasmic reticulum-derived compartments permissive for bacterial replication. Brucella Type IV Secretion System (VirB) is a major virulence factor essential for the biogenesis of the replicative organelle. Upon infection, Brucella uses the VirB system to translocate effector proteins from the BCV into the host cell cytoplasm. Although the functions of many translocated proteins remain unknown, some of them have been demonstrated to modulate host cell signaling pathways to favor intracellular survival and replication. BPE123 (BAB2_0123) is a B. abortus VirB-translocated effector protein recently identified by our group whose function is yet unknown. In an attempt to identify host cell proteins interacting with BPE123, a pull-down assay was performed and human alpha-enolase (ENO-1) was identified by LC/MS-MS as a potential interaction partner of BPE123. These results were confirmed by immunoprecipitation assays. In bone-marrow derived macrophages infected with B. abortus, ENO-1 associates to BCVs in a BPE123-dependent manner, indicating that interaction with translocated BPE123 is also occurring during the intracellular phase of the bacterium. Furthermore, ENO-1 depletion by siRNA impaired B. abortus intracellular replication in HeLa cells, confirming a role for α-enolase during the infection process. Indeed, ENO-1 activity levels were enhanced upon B. abortus infection of THP-1 macrophagic cells, and this activation is highly dependent on BPE123. Taken together, these results suggest that interaction between BPE123 and host cell ENO-1 contributes to the intracellular lifestyle of B. abortus.
Collapse
Affiliation(s)
- María I Marchesini
- Instituto de Investigaciones Biotecnológicas "Dr. Rodolfo A. Ugalde," Instituto Tecnológico de Chascomús, CONICET, Universidad Nacional de San Martín Buenos Aires, Argentina
| | - Susana M Morrone Seijo
- Instituto de Investigaciones Biotecnológicas "Dr. Rodolfo A. Ugalde," Instituto Tecnológico de Chascomús, CONICET, Universidad Nacional de San Martín Buenos Aires, Argentina
| | - Francisco F Guaimas
- Instituto de Investigaciones Biotecnológicas "Dr. Rodolfo A. Ugalde," Instituto Tecnológico de Chascomús, CONICET, Universidad Nacional de San Martín Buenos Aires, Argentina
| | - Diego J Comerci
- Instituto de Investigaciones Biotecnológicas "Dr. Rodolfo A. Ugalde," Instituto Tecnológico de Chascomús, CONICET, Universidad Nacional de San MartínBuenos Aires, Argentina; Comisión Nacional de Energía Atómica, Grupo Pecuario, Centro Atómico EzeizaBuenos Aires, Argentina
| |
Collapse
|
46
|
Legionella pneumophila prevents proliferation of its natural host Acanthamoeba castellanii. Sci Rep 2016; 6:36448. [PMID: 27805070 PMCID: PMC5091012 DOI: 10.1038/srep36448] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Accepted: 10/14/2016] [Indexed: 12/12/2022] Open
Abstract
Legionella pneumophila is a ubiquitous, pathogenic, Gram-negative bacterium responsible for legionellosis. Like many other amoeba-resistant microorganisms, L. pneumophila resists host clearance and multiplies inside the cell. Through its Dot/Icm type IV secretion system, the bacterium injects more than three hundred effectors that modulate host cell physiology in order to promote its own intracellular replication. Here we report that L. pneumophila prevents proliferation of its natural host Acanthamoeba castellanii. Infected amoebae could not undergo DNA replication and no cell division was observed. The Dot/Icm secretion system was necessary for L. pneumophila to prevent the eukaryotic proliferation. The absence of proliferation was associated with altered amoebal morphology and with a decrease of mRNA transcript levels of CDC2b, a putative regulator of the A. castellanii cell cycle. Complementation of CDC28-deficient Saccharomyces cerevisiae by the CDC2b cDNA was sufficient to restore proliferation of CDC28-deficient S. cerevisiae and suggests for the first time that CDC2b from A. castellanii could be functional and a bona fide cyclin-dependent kinase. Hence, our results reveal that L. pneumophila impairs proliferation of A. castellanii and this effect could involve the cell cycle protein CDC2b.
Collapse
|
47
|
Malik E, Dennison SR, Harris F, Phoenix DA. pH Dependent Antimicrobial Peptides and Proteins, Their Mechanisms of Action and Potential as Therapeutic Agents. Pharmaceuticals (Basel) 2016; 9:ph9040067. [PMID: 27809281 PMCID: PMC5198042 DOI: 10.3390/ph9040067] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Revised: 10/25/2016] [Accepted: 10/26/2016] [Indexed: 12/16/2022] Open
Abstract
Antimicrobial peptides (AMPs) are potent antibiotics of the innate immune system that have been extensively investigated as a potential solution to the global problem of infectious diseases caused by pathogenic microbes. A group of AMPs that are increasingly being reported are those that utilise pH dependent antimicrobial mechanisms, and here we review research into this area. This review shows that these antimicrobial molecules are produced by a diverse spectrum of creatures, including vertebrates and invertebrates, and are primarily cationic, although a number of anionic examples are known. Some of these molecules exhibit high pH optima for their antimicrobial activity but in most cases, these AMPs show activity against microbes that present low pH optima, which reflects the acidic pH generally found at their sites of action, particularly the skin. The modes of action used by these molecules are based on a number of major structure/function relationships, which include metal ion binding, changes to net charge and conformational plasticity, and primarily involve the protonation of histidine, aspartic acid and glutamic acid residues at low pH. The pH dependent activity of pore forming antimicrobial proteins involves mechanisms that generally differ fundamentally to those used by pH dependent AMPs, which can be described by the carpet, toroidal pore and barrel-stave pore models of membrane interaction. A number of pH dependent AMPs and antimicrobial proteins have been developed for medical purposes and have successfully completed clinical trials, including kappacins, LL-37, histatins and lactoferrin, along with a number of their derivatives. Major examples of the therapeutic application of these antimicrobial molecules include wound healing as well as the treatment of multiple cancers and infections due to viruses, bacteria and fungi. In general, these applications involve topical administration, such as the use of mouth washes, cream formulations and hydrogel delivery systems. Nonetheless, many pH dependent AMPs and antimicrobial proteins have yet to be fully characterized and these molecules, as a whole, represent an untapped source of novel biologically active agents that could aid fulfillment of the urgent need for alternatives to conventional antibiotics, helping to avert a return to the pre-antibiotic era.
Collapse
Affiliation(s)
- Erum Malik
- School of Forensic and Applied Sciences, University of Central Lancashire, Preston PR1 2HE, UK.
| | - Sarah R Dennison
- School of Pharmacy and Biological Sciences, University of Central Lancashire, Preston PR1 2HE, UK.
| | - Frederick Harris
- School of Forensic and Applied Sciences, University of Central Lancashire, Preston PR1 2HE, UK.
| | - David A Phoenix
- Office of the Vice Chancellor, London South Bank University, 103 Borough Road, London SE1 0AA, UK.
| |
Collapse
|
48
|
Direct targeting of membrane fusion by SNARE mimicry: Convergent evolution of Legionella effectors. Proc Natl Acad Sci U S A 2016; 113:8807-12. [PMID: 27436892 DOI: 10.1073/pnas.1608755113] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Legionella pneumophila, the Gram-negative pathogen causing Legionnaires' disease, infects host cells by hijacking endocytic pathways and forming a Legionella-containing vacuole (LCV) in which the bacteria replicate. To promote LCV expansion and prevent lysosomal targeting, effector proteins are translocated into the host cell where they alter membrane traffic. Here we show that three of these effectors [LegC2 (Legionella eukaryotic-like gene C2)/YlfB (yeast lethal factor B), LegC3, and LegC7/YlfA] functionally mimic glutamine (Q)-SNARE proteins. In infected cells, the three proteins selectively form complexes with the endosomal arginine (R)-SNARE vesicle-associated membrane protein 4 (VAMP4). When reconstituted in proteoliposomes, these proteins avidly fuse with liposomes containing VAMP4, resulting in a stable complex with properties resembling canonical SNARE complexes. Intriguingly, however, the LegC/SNARE hybrid complex cannot be disassembled by N-ethylmaleimide-sensitive factor. We conclude that LegCs use SNARE mimicry to divert VAMP4-containing vesicles for fusion with the LCV, thus promoting its expansion. In addition, the LegC/VAMP4 complex avoids the host's disassembly machinery, thus effectively trapping VAMP4 in an inactive state.
Collapse
|
49
|
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.
Collapse
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)
| |
Collapse
|
50
|
Borges V, Nunes A, Sampaio DA, Vieira L, Machado J, Simões MJ, Gonçalves P, Gomes JP. Legionella pneumophila strain associated with the first evidence of person-to-person transmission of Legionnaires' disease: a unique mosaic genetic backbone. Sci Rep 2016; 6:26261. [PMID: 27196677 PMCID: PMC4872527 DOI: 10.1038/srep26261] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 04/29/2016] [Indexed: 01/23/2023] Open
Abstract
A first strong evidence of person-to-person transmission of Legionnaires’ Disease (LD) was recently reported. Here, we characterize the genetic backbone of this case-related Legionella pneumophila strain (“PtVFX/2014”), which also caused a large outbreak of LD. PtVFX/2014 is phylogenetically divergent from the most worldwide studied outbreak-associated L. pneumophila subspecies pneumophila serogroup 1 strains. In fact, this strain is also from serogroup 1, but belongs to the L. pneumophila subspecies fraseri. Its genomic mosaic backbone reveals eight horizontally transferred regions encompassing genes, for instance, involved in lipopolysaccharide biosynthesis or encoding virulence-associated Dot/Icm type IVB secretion system (T4BSS) substrates. PtVFX/2014 also inherited a rare ~65 kb pathogenicity island carrying virulence factors and detoxifying enzymes believed to contribute to the emergence of best-fitted strains in water reservoirs and in human macrophages, as well as a inter-species transferred (from L. oakridgensis) ~37.5 kb genomic island (harboring a lvh/lvr T4ASS cluster) that had never been found intact within L. pneumophila species. PtVFX/2014 encodes another lvh/lvr cluster near to CRISPR-associated genes, which may boost L. pneumophila transition from an environmental bacterium to a human pathogen. Overall, this unique genomic make-up may impact PtVFX/2014 ability to adapt to diverse environments, and, ultimately, to be transmitted and cause human disease.
Collapse
Affiliation(s)
- Vítor Borges
- Bioinformatics Unit and Research Unit, National Institute of Health, Lisbon, Portugal
| | - Alexandra Nunes
- Bioinformatics Unit and Research Unit, National Institute of Health, Lisbon, Portugal
| | - Daniel A Sampaio
- Innovation and Technology Unit, National Institute of Health, Lisbon, Portugal
| | - Luís Vieira
- Innovation and Technology Unit, National Institute of Health, Lisbon, Portugal
| | - Jorge Machado
- Coordination of the Department of Infectious Diseases, National Institute of Health, Lisbon, Portugal
| | - Maria J Simões
- National Reference Laboratory for Legionella, National Institute of Health, Lisbon, Portugal
| | - Paulo Gonçalves
- National Reference Laboratory for Legionella, National Institute of Health, Lisbon, Portugal
| | - João P Gomes
- Bioinformatics Unit and Research Unit, National Institute of Health, Lisbon, Portugal
| |
Collapse
|