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Yang Y, Mei L, Chen J, Chen X, Wang Z, Liu L, Yang A. Legionella pneumophila-mediated host posttranslational modifications. J Mol Cell Biol 2023; 15:mjad032. [PMID: 37156500 PMCID: PMC10720952 DOI: 10.1093/jmcb/mjad032] [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: 09/16/2022] [Revised: 01/17/2023] [Accepted: 05/06/2023] [Indexed: 05/10/2023] Open
Abstract
Legionella pneumophila is a Gram-negative bacterium ubiquitously present in freshwater environments and causes a serious type of pneumonia called Legionnaires' disease. During infections, L. pneumophila releases over 300 effector proteins into host cells through an Icm/Dot type IV secretion system to manipulate the host defense system for survival within the host. Notably, certain effector proteins mediate posttranslational modifications (PTMs), serving as useful approaches exploited by L. pneumophila to modify host proteins. Some effectors catalyze the addition of host protein PTMs, while others mediate the removal of PTMs from host proteins. In this review, we summarize L. pneumophila effector-mediated PTMs of host proteins, including phosphorylation, ubiquitination, glycosylation, AMPylation, phosphocholination, methylation, and ADP-ribosylation, as well as dephosphorylation, deubiquitination, deAMPylation, deADP-ribosylation, dephosphocholination, and delipidation. We describe their molecular mechanisms and biological functions in the regulation of bacterial growth and Legionella-containing vacuole biosynthesis and in the disruption of host immune and defense machinery.
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Affiliation(s)
- Yi Yang
- School of Life Sciences, Chongqing University, Chongqing 401331, China
| | - Ligang Mei
- School of Life Sciences, Chongqing University, Chongqing 401331, China
| | - Jing Chen
- School of Life Sciences, Chongqing University, Chongqing 401331, China
| | - Xiaorong Chen
- School of Life Sciences, Chongqing University, Chongqing 401331, China
| | - Zhuolin Wang
- School of Life Sciences, Chongqing University, Chongqing 401331, China
| | - Lu Liu
- School of Life Sciences, Chongqing University, Chongqing 401331, China
| | - Aimin Yang
- School of Life Sciences, Chongqing University, Chongqing 401331, China
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2
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Lockwood DC, Amin H, Costa TRD, Schroeder GN. The Legionella pneumophila Dot/Icm type IV secretion system and its effectors. MICROBIOLOGY (READING, ENGLAND) 2022; 168. [PMID: 35639581 DOI: 10.1099/mic.0.001187] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
To prevail in the interaction with eukaryotic hosts, many bacterial pathogens use protein secretion systems to release virulence factors at the host–pathogen interface and/or deliver them directly into host cells. An outstanding example of the complexity and sophistication of secretion systems and the diversity of their protein substrates, effectors, is the Defective in organelle trafficking/Intracellular multiplication (Dot/Icm) Type IVB secretion system (T4BSS) of
Legionella pneumophila
and related species.
Legionella
species are facultative intracellular pathogens of environmental protozoa and opportunistic human respiratory pathogens. The Dot/Icm T4BSS translocates an exceptionally large number of effectors, more than 300 per
L. pneumophila
strain, and is essential for evasion of phagolysosomal degradation and exploitation of protozoa and human macrophages as replicative niches. Recent technological advancements in the imaging of large protein complexes have provided new insight into the architecture of the T4BSS and allowed us to propose models for the transport mechanism. At the same time, significant progress has been made in assigning functions to about a third of
L. pneumophila
effectors, discovering unprecedented new enzymatic activities and concepts of host subversion. In this review, we describe the current knowledge of the workings of the Dot/Icm T4BSS machinery and provide an overview of the activities and functions of the to-date characterized effectors in the interaction of
L. pneumophila
with host cells.
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Affiliation(s)
- Daniel C Lockwood
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, BT9 7BL, Northern Ireland, UK
| | - Himani Amin
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College, London, SW7 2AZ, UK
| | - Tiago R D Costa
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College, London, SW7 2AZ, UK
| | - Gunnar N Schroeder
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, BT9 7BL, Northern Ireland, UK
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3
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Liu K, Kong L, Graham DB, Carey KL, Xavier RJ. SAC1 regulates autophagosomal phosphatidylinositol-4-phosphate for xenophagy-directed bacterial clearance. Cell Rep 2021; 36:109434. [PMID: 34320354 PMCID: PMC8327279 DOI: 10.1016/j.celrep.2021.109434] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Revised: 12/21/2020] [Accepted: 07/01/2021] [Indexed: 02/07/2023] Open
Abstract
Phosphoinositides are important molecules in lipid signaling, membrane identity, and trafficking that are spatiotemporally controlled by factors from both mammalian cells and intracellular pathogens. Here, using small interfering RNA (siRNA) directed against phosphoinositide kinases and phosphatases, we screen for regulators of the host innate defense response to intracellular bacterial replication. We identify SAC1, a transmembrane phosphoinositide phosphatase, as an essential regulator of xenophagy. Depletion or inactivation of SAC1 compromises fusion between Salmonella-containing autophagosomes and lysosomes, leading to increased bacterial replication. Mechanistically, the loss of SAC1 results in aberrant accumulation of phosphatidylinositol-4-phosphate [PI(4)P] on Salmonella-containing autophagosomes, thus facilitating recruitment of SteA, a PI(4)P-binding Salmonella effector protein, which impedes lysosomal fusion. Replication of Salmonella lacking SteA is suppressed by SAC-1-deficient cells, however, demonstrating bacterial adaptation to xenophagy. Our findings uncover a paradigm in which a host protein regulates the level of its substrate and impairs the function of a bacterial effector during xenophagy.
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Affiliation(s)
- Kai Liu
- Center for Computational and Integrative Biology, Department of Molecular Biology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Lingjia Kong
- Center for Computational and Integrative Biology, Department of Molecular Biology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA
| | - Daniel B Graham
- Center for Computational and Integrative Biology, Department of Molecular Biology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Center for the Study of Inflammatory Bowel Disease, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA; Klarman Cell Observatory, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | | | - Ramnik J Xavier
- Center for Computational and Integrative Biology, Department of Molecular Biology, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Center for the Study of Inflammatory Bowel Disease, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02114, USA; Klarman Cell Observatory, Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA.
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4
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Liu S, Luo J, Zhen X, Qiu J, Ouyang S, Luo ZQ. Interplay between bacterial deubiquitinase and ubiquitin E3 ligase regulates ubiquitin dynamics on Legionella phagosomes. eLife 2020; 9:58114. [PMID: 33136002 PMCID: PMC7669269 DOI: 10.7554/elife.58114] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Accepted: 11/01/2020] [Indexed: 12/12/2022] Open
Abstract
Legionella pneumophila extensively modulates the host ubiquitin network to create the Legionella-containing vacuole (LCV) for its replication. Many of its virulence factors function as ubiquitin ligases or deubiquitinases (DUBs). Here, we identify Lem27 as a DUB that displays a preference for diubiquitin formed by K6, K11, or K48. Lem27 is associated with the LCV where it regulates Rab10 ubiquitination in concert with SidC and SdcA, two bacterial E3 ubiquitin ligases. Structural analysis of the complex formed by an active fragment of Lem27 and the substrate-based suicide inhibitor ubiquitin-propargylamide (PA) reveals that it harbors a fold resembling those in the OTU1 DUB subfamily with a Cys-His catalytic dyad and that it recognizes ubiquitin via extensive hydrogen bonding at six contact sites. Our results establish Lem27 as a DUB that functions to regulate protein ubiquitination on L. pneumophila phagosomes by counteracting the activity of bacterial ubiquitin E3 ligases.
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Affiliation(s)
- Shuxin Liu
- Department of Respiratory Medicine and Center of Infection and Immunity, Key Laboratory of Organ Regeneration and Transplantation of the Ministry of Education, The First Hospital, Jilin University, Changchun, China
| | - Jiwei Luo
- The Key Laboratory of Innate Immune Biology of Fujian Province, Provincial University Key Laboratory of Cellular Stress Response and Metabolic Regulation, Biomedical Research Center of South China, Key Laboratory of OptoElectronic Science and Technology for Medicine of the Ministry of Education, College of Life Sciences, Fujian Normal University, Fuzhou, China.,Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, China
| | - Xiangkai Zhen
- The Key Laboratory of Innate Immune Biology of Fujian Province, Provincial University Key Laboratory of Cellular Stress Response and Metabolic Regulation, Biomedical Research Center of South China, Key Laboratory of OptoElectronic Science and Technology for Medicine of the Ministry of Education, College of Life Sciences, Fujian Normal University, Fuzhou, China.,Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, China
| | - Jiazhang Qiu
- Key Laboratory of Zoonosis, Ministry of Education, College of Veterinary Medicine, Jilin University, Changchun, China
| | - Songying Ouyang
- The Key Laboratory of Innate Immune Biology of Fujian Province, Provincial University Key Laboratory of Cellular Stress Response and Metabolic Regulation, Biomedical Research Center of South China, Key Laboratory of OptoElectronic Science and Technology for Medicine of the Ministry of Education, College of Life Sciences, Fujian Normal University, Fuzhou, China.,Laboratory for Marine Biology and Biotechnology, Pilot National Laboratory for Marine Science and Technology (Qingdao), Qingdao, China
| | - Zhao-Qing Luo
- Department of Respiratory Medicine and Center of Infection and Immunity, Key Laboratory of Organ Regeneration and Transplantation of the Ministry of Education, The First Hospital, Jilin University, Changchun, China.,Department of Biological Sciences, Purdue University, West Lafayette, United States
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5
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Sreelatha A, Nolan C, Park BC, Pawłowski K, Tomchick DR, Tagliabracci VS. A Legionella effector kinase is activated by host inositol hexakisphosphate. J Biol Chem 2020; 295:6214-6224. [PMID: 32229585 DOI: 10.1074/jbc.ra120.013067] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 03/26/2020] [Indexed: 12/18/2022] Open
Abstract
The transfer of a phosphate from ATP to a protein substrate, a modification known as protein phosphorylation, is catalyzed by protein kinases. Protein kinases play a crucial role in virtually every cellular activity. Recent studies of atypical protein kinases have highlighted the structural similarity of the kinase superfamily despite notable differences in primary amino acid sequence. Here, using a bioinformatics screen, we searched for putative protein kinases in the intracellular bacterial pathogen Legionella pneumophila and identified the type 4 secretion system effector Lpg2603 as a remote member of the protein kinase superfamily. Employing an array of biochemical and structural biology approaches, including in vitro kinase assays and isothermal titration calorimetry, we show that Lpg2603 is an active protein kinase with several atypical structural features. Importantly, we found that the eukaryote-specific host signaling molecule inositol hexakisphosphate (IP6) is required for Lpg2603 kinase activity. Crystal structures of Lpg2603 in the apo-form and when bound to IP6 revealed an active-site rearrangement that allows for ATP binding and catalysis. Our results on the structure and activity of Lpg2603 reveal a unique mode of regulation of a protein kinase, provide the first example of a bacterial kinase that requires IP6 for its activation, and may aid future work on the function of this effector during Legionella pathogenesis.
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Affiliation(s)
- Anju Sreelatha
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, Texas 75390.
| | - Christine Nolan
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Brenden C Park
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Krzysztof Pawłowski
- Institute of Biology, Warsaw University of Life Sciences, Warsaw 02-787, Poland
| | - Diana R Tomchick
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, Texas 75390; Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas 75390
| | - Vincent S Tagliabracci
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, Texas 75390; Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, Texas 75390; Hamon Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75390.
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6
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Yáñez JM, Yoshida GM, Parra Á, Correa K, Barría A, Bassini LN, Christensen KA, López ME, Carvalheiro R, Lhorente JP, Pulgar R. Comparative Genomic Analysis of Three Salmonid Species Identifies Functional Candidate Genes Involved in Resistance to the Intracellular Bacterium Piscirickettsia salmonis. Front Genet 2019; 10:665. [PMID: 31428125 PMCID: PMC6690157 DOI: 10.3389/fgene.2019.00665] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2019] [Accepted: 06/25/2019] [Indexed: 12/23/2022] Open
Abstract
Piscirickettsia salmonis is the etiologic agent of salmon rickettsial syndrome (SRS) and is responsible for considerable economic losses in salmon aquaculture. The bacterium affects coho salmon (CS; Oncorhynchus kisutch), Atlantic salmon (AS; Salmo salar), and rainbow trout (RT; Oncorhynchus mykiss) in several countries, including Norway, Canada, Scotland, Ireland, and Chile. We used Bayesian genome-wide association study analyses to investigate the genetic architecture of resistance to P. salmonis in farmed populations of these species. Resistance to SRS was defined as the number of days to death and as binary survival (BS). A total of 828 CS, 2130 RT, and 2601 AS individuals were phenotyped and then genotyped using double-digest restriction site-associated DNA sequencing and 57K and 50K Affymetrix® Axiom® single nucleotide polymorphism (SNP) panels, respectively. Both traits of SRS resistance in CS and RT appeared to be under oligogenic control. In AS, there was evidence of polygenic control of SRS resistance. To identify candidate genes associated with resistance, we applied a comparative genomics approach in which we systematically explored the complete set of genes adjacent to SNPs, which explained more than 1% of the genetic variance of resistance in each salmonid species (533 genes in total). Thus, genes were classified based on the following criteria: i) shared function of their protein domains among species, ii) shared orthology among species, iii) proximity to the SNP explaining the highest proportion of the genetic variance, and iv) presence in more than one genomic region explaining more than 1% of the genetic variance within species. Our results allowed us to identify 120 candidate genes belonging to at least one of the four criteria described above. Of these, 21 of them were part of at least two of the criteria defined above and are suggested to be strong functional candidates influencing P. salmonis resistance. These genes are related to diverse biological processes, such as kinase activity, GTP hydrolysis, helicase activity, lipid metabolism, cytoskeletal dynamics, inflammation, and innate immune response, which seem essential in the host response against P. salmonis infection. These results provide fundamental knowledge on the potential functional genes underpinning resistance against P. salmonis in three salmonid species.
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Affiliation(s)
- José M. Yáñez
- Facultad de Ciencias Veterinarias y Pecuarias, Universidad de Chile, Santiago, Chile
- Núcleo Milenio INVASAL, Concepción, Chile
| | - Grazyella M. Yoshida
- Facultad de Ciencias Veterinarias y Pecuarias, Universidad de Chile, Santiago, Chile
| | - Ángel Parra
- Facultad de Ciencias Veterinarias y Pecuarias, Universidad de Chile, Santiago, Chile
- Instituto de Nutrición y Tecnología de los Alimentos, Universidad de Chile, Santiago, Chile
- Doctorado en Acuicultura. Programa Cooperativo Universidad de Chile, Universidad Católica del Norte, Pontificia Universidad Católica de Valparaíso, Valparaíso, Chile
- Facultad de Ciencias del Mar, Universidad Católica del Norte, Coquimbo, Chile
| | | | - Agustín Barría
- Facultad de Ciencias Veterinarias y Pecuarias, Universidad de Chile, Santiago, Chile
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of Edinburgh Easter Bush, Midlothian, United Kingdom
| | - Liane N. Bassini
- Escuela de Medicina Veterinaria, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | | | - Maria E. López
- Facultad de Ciencias Veterinarias y Pecuarias, Universidad de Chile, Santiago, Chile
- Department of Animal Breeding and Genetics, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Roberto Carvalheiro
- School of Agricultural and Veterinarian Sciences, São Paulo State University (Unesp), Jaboticabal, Brazil
- National Council for Scientific and Technological Development (CNPq), Brasília, Brazil
| | | | - Rodrigo Pulgar
- Instituto de Nutrición y Tecnología de los Alimentos, Universidad de Chile, Santiago, Chile
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7
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Quaile AT, Stogios PJ, Egorova O, Evdokimova E, Valleau D, Nocek B, Kompella PS, Peisajovich S, Yakunin AF, Ensminger AW, Savchenko A. The Legionella pneumophila effector Ceg4 is a phosphotyrosine phosphatase that attenuates activation of eukaryotic MAPK pathways. J Biol Chem 2018; 293:3307-3320. [PMID: 29301934 DOI: 10.1074/jbc.m117.812727] [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: 08/17/2017] [Revised: 12/18/2017] [Indexed: 01/08/2023] Open
Abstract
Host colonization by Gram-negative pathogens often involves delivery of bacterial proteins called "effectors" into the host cell. The pneumonia-causing pathogen Legionella pneumophila delivers more than 330 effectors into the host cell via its type IVB Dot/Icm secretion system. The collective functions of these proteins are the establishment of a replicative niche from which Legionella can recruit cellular materials to grow while evading lysosomal fusion inhibiting its growth. Using a combination of structural, biochemical, and in vivo approaches, we show that one of these translocated effector proteins, Ceg4, is a phosphotyrosine phosphatase harboring a haloacid dehalogenase-hydrolase domain. Ceg4 could dephosphorylate a broad range of phosphotyrosine-containing peptides in vitro and attenuated activation of MAPK-controlled pathways in both yeast and human cells. Our findings indicate that L. pneumophila's infectious program includes manipulation of phosphorylation cascades in key host pathways. The structural and functional features of the Ceg4 effector unraveled here provide first insight into its function as a phosphotyrosine phosphatase, paving the way to further studies into L. pneumophila pathogenicity.
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Affiliation(s)
- Andrew T Quaile
- From the Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario M5S 3E5, Canada
| | - Peter J Stogios
- From the Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario M5S 3E5, Canada
| | - Olga Egorova
- From the Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario M5S 3E5, Canada
| | - Elena Evdokimova
- From the Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario M5S 3E5, Canada
| | - Dylan Valleau
- From the Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario M5S 3E5, Canada
| | - Boguslaw Nocek
- Structural Biology Center, Advanced Photon Source, Argonne National Laboratory, Lemont, Illinois 60439
| | - Purnima S Kompella
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario M5S 3G5, Canada
| | - Sergio Peisajovich
- Department of Cell and Systems Biology, University of Toronto, Toronto, Ontario M5S 3G5, Canada
| | - Alexander F Yakunin
- From the Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario M5S 3E5, Canada
| | - Alexander W Ensminger
- Department of Biochemistry, Department of Molecular Genetics, University of Toronto, Toronto, Ontario M5G 1M1, Canada, and
| | - Alexei Savchenko
- From the Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario M5S 3E5, Canada, .,Department of Microbiology, Immunology and Infectious Diseases, Cumming School of Medicine, University of Calgary, Calgary, Alberta T2N 4N1, Canada
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8
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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.
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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
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9
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Eisenreich W, Heuner K. The life stage-specific pathometabolism of Legionella pneumophila. FEBS Lett 2016; 590:3868-3886. [PMID: 27455397 DOI: 10.1002/1873-3468.12326] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Revised: 07/08/2016] [Accepted: 07/21/2016] [Indexed: 12/17/2022]
Abstract
The genus Legionella belongs to Gram-negative bacteria found ubiquitously in aquatic habitats, where it grows in natural biofilms and replicates intracellularly in various protozoa (amoebae, ciliates). L. pneumophila is known as the causative agent of Legionnaires' disease, since it is also able to replicate in human alveolar macrophages, finally leading to inflammation of the lung and pneumonia. To withstand the degradation by its host cells, a Legionella-containing vacuole (LCV) is established for intracellular replication, and numerous effector proteins are secreted into the host cytosol using a type four B secretion system (T4BSS). During intracellular replication, Legionella has a biphasic developmental cycle that alternates between a replicative and a transmissive form. New knowledge about the host-adapted and life stage-dependent metabolism of intracellular L. pneumophila revealed a bipartite metabolic network with life stage-specific usages of amino acids (e.g. serine), carbohydrates (e.g. glucose) and glycerol as major substrates. These metabolic features are associated with the differentiation of the intracellular bacteria, and thus have an important impact on the virulence of L. pneumophila.
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Affiliation(s)
| | - Klaus Heuner
- Cellular Interactions of Bacterial Pathogens, ZBS 2, Robert Koch Institute, Berlin, Germany
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10
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Burkholderia pseudomallei Differentially Regulates Host Innate Immune Response Genes for Intracellular Survival in Lung Epithelial Cells. PLoS Negl Trop Dis 2016; 10:e0004730. [PMID: 27367858 PMCID: PMC4930195 DOI: 10.1371/journal.pntd.0004730] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2015] [Accepted: 05/02/2016] [Indexed: 01/06/2023] Open
Abstract
Background Burkholderia pseudomallei, the causative agent of melioidosis poses a serious threat to humankind. B. pseudomallei secretes numerous virulence proteins that alter host cell functions to escape from intracellular immune sensors. However, the events underlying disease pathogenesis are poorly understood. Methods We determined the ability of B. pseudomallei to invade and survive intracellularly in A549 human lung epithelial cells, and also investigated the early transcriptional responses using an Illumina HumanHT-12 v4 microarray platform, after three hours of exposure to live B. pseudomallei (BCMS) and its secreted proteins (CCMS). Results We found that the ability of B. pseudomallei to invade and survive intracellularly correlated with increase of multiplicity of infection and duration of contact. Activation of host carbohydrate metabolism and apoptosis as well as suppression of amino acid metabolism and innate immune responses both by live bacteria and its secreted proteins were evident. These early events might be linked to initial activation of host genes directed towards bacterial dissemination from lungs to target organs (via proposed in vivo mechanisms) or to escape potential sensing by macrophages. Conclusion Understanding the early responses of A549 cells toward B. pseudomallei infection provide preliminary insights into the likely pathogenesis mechanisms underlying melioidosis, and could contribute to development of novel intervention strategies to combat B. pseudomallei infections. Burkholderia pseudomallei, the causative agent of the fatal infectious disease melioidosis, is endemic across parts of South East Asia and Northern Australia. Melioidosis poses a serious worldwide emerging infectious disease problem and bioterrorism threat. Of the key features of B. pseudomallei, is its ability to remain latent in the host causing recrudescent disease years after initial infection. Relapses are also commonly reported despite appropriate and prolonged antibiotic therapy, suggesting the bacteria’s ability to escape the host’s front-line immune defenses and to manipulate the host’s responses to sustain survival in the host. However, the likely underlying mechanisms of bacterial persistence still remain unclear. Thus, here we proposed to study the host responses towards early interaction of the cell with live B. pseudomallei and its secretory proteins, in order to understand the potential roles of innate responses against the bacteria.
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11
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Host-directed antimicrobial drugs with broad-spectrum efficacy against intracellular bacterial pathogens. mBio 2014; 5:e01534-14. [PMID: 25073644 PMCID: PMC4128363 DOI: 10.1128/mbio.01534-14] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We sought a new approach to treating infections by intracellular bacteria, namely, by altering host cell functions that support their growth. We screened a library of 640 Food and Drug Administration (FDA)-approved compounds for agents that render THP-1 cells resistant to infection by four intracellular pathogens. We identified numerous drugs that are not antibiotics but were highly effective in inhibiting intracellular bacterial growth with limited toxicity to host cells. These compounds are likely to target three kinds of host functions: (i) G protein-coupled receptors, (ii) intracellular calcium signals, and (iii) membrane cholesterol distribution. The compounds that targeted G protein receptor signaling and calcium fluxes broadly inhibited Coxiella burnetii, Legionella pneumophila, Brucella abortus, and Rickettsia conorii, while those directed against cholesterol traffic strongly attenuated the intracellular growth of C. burnetii and L. pneumophila. These pathways probably support intracellular pathogen growth so that drugs that perturb them may be therapeutic candidates. Combining host- and pathogen-directed treatments is a strategy to decrease the emergence of drug-resistant intracellular bacterial pathogens. Although antibiotic treatment is often successful, it is becoming clear that alternatives to conventional pathogen-directed therapy must be developed in the face of increasing antibiotic resistance. Moreover, the costs and timing associated with the development of novel antimicrobials make repurposed FDA-approved drugs attractive host-targeted therapeutics. This paper describes a novel approach of identifying such host-targeted therapeutics against intracellular bacterial pathogens. We identified several FDA-approved drugs that inhibit the growth of intracellular bacteria, thereby implicating host intracellular pathways presumably utilized by bacteria during infection.
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12
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Eisenreich W, Heesemann J, Rudel T, Goebel W. Metabolic host responses to infection by intracellular bacterial pathogens. Front Cell Infect Microbiol 2013; 3:24. [PMID: 23847769 PMCID: PMC3705551 DOI: 10.3389/fcimb.2013.00024] [Citation(s) in RCA: 135] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Accepted: 06/11/2013] [Indexed: 12/12/2022] Open
Abstract
The interaction of bacterial pathogens with mammalian hosts leads to a variety of physiological responses of the interacting partners aimed at an adaptation to the new situation. These responses include multiple metabolic changes in the affected host cells which are most obvious when the pathogen replicates within host cells as in case of intracellular bacterial pathogens. While the pathogen tries to deprive nutrients from the host cell, the host cell in return takes various metabolic countermeasures against the nutrient theft. During this conflicting interaction, the pathogen triggers metabolic host cell responses by means of common cell envelope components and specific virulence-associated factors. These host reactions generally promote replication of the pathogen. There is growing evidence that pathogen-specific factors may interfere in different ways with the complex regulatory network that controls the carbon and nitrogen metabolism of mammalian cells. The host cell defense answers include general metabolic reactions, like the generation of oxygen- and/or nitrogen-reactive species, and more specific measures aimed to prevent access to essential nutrients for the respective pathogen. Accurate results on metabolic host cell responses are often hampered by the use of cancer cell lines that already exhibit various de-regulated reactions in the primary carbon metabolism. Hence, there is an urgent need for cellular models that more closely reflect the in vivo infection conditions. The exact knowledge of the metabolic host cell responses may provide new interesting concepts for antibacterial therapies.
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Affiliation(s)
- Wolfgang Eisenreich
- Lehrstuhl für Biochemie, Center of Isotopologue Profiling, Technische Universität München Garching, Germany
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Host signal transduction and protein kinases implicated in Legionella infection. Curr Top Microbiol Immunol 2013; 376:249-69. [PMID: 23918173 DOI: 10.1007/82_2013_342] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Modulation of the phosphorylation status of proteins by both kinases and phosphatases plays an important role in cellular signal transduction. Challenge of host cells by Legionella pneumophila manipulates the phosphorylation state of multiple host factors. These changes play roles in bacterial uptake, vacuole modification, cellular survival, and the immune response. In addition to modification by host cell kinases in response to the bacterium, L. pneumophila translocates bacterial kinases into the host cell that may contribute to further signaling modifications. Proper regulation of host cell signaling by L. pneumophila is necessary for its ability to replicate intracellulary, while avoiding host defenses.
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Abstract
Legionella is a gram-negative bacterium and the causative pathogen of legionellosis-a severe pneumonia in humans. A large number of Legionella effectors interfere with numerous host cell functions, including intracellular vacuole trafficking and maturation, phospholipid metabolism, protein ubiquitination, pro-/anti-apoptotic balances or inflammatory responses. Moreover, eukaryotic protein synthesis is affected by L. pneumophila glucosyltransferases Lgt1, Lgt2, and Lgt3. Structurally, these enzymes are similar to large clostridial cytotoxins, use UDP-glucose as a co-substrate and modify a conserved serine residue (Ser-53) in elongation factor 1A (eEF1A). The ternary complex consisting of eEF1A, GTP, and aminoacylated-tRNA seems to be the substrate for Lgts. Studies with Saccharomyces cerevisiae corroborated that eEF1A is the major target responsible for Lgt-induced cytotoxic activity. In addition to Lgt proteins, Legionella produces other effector glycosyltransferase, including the modularly composed protein SetA, which displays tropism for early endosomal compartments, subverts host cell vesicle trafficking and demonstrates toxic activities toward yeast and mammalian cells. Here, our current knowledge about both groups of L. pneumophila glycosylating effectors is reviewed.
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Activation of host mitogen-activated protein kinases by secreted Legionella pneumophila effectors that inhibit host protein translation. Infect Immun 2012; 80:3570-5. [PMID: 22851749 DOI: 10.1128/iai.00557-12] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Studies of innate immunity in metazoans have largely focused on detection of microbial molecules by host pattern recognition receptors (PRRs). A complementary mode of innate immune recognition, based on detection of pathogen-encoded activities, has long been recognized in plants, where it is termed effector-triggered immunity; however, little is known about the possibility of effector-triggered immunity in metazoans. Legionella pneumophila is an intracellular bacterial pathogen that causes Legionnaires' disease, an inflammatory pneumonia. We recently demonstrated that macrophages infected with L. pneumophila exhibit mitogen-activated protein (MAP) kinase (MAPK) activation that is independent of known PRRs but dependent on a functional bacterial secretion system. Here, we show that five secreted L. pneumophila effectors are responsible for the activation of host MAP kinases. These five effectors inhibit host translation, and their activity is required for host MAPK activation. We demonstrate that MAPK activation by these effectors shapes the host transcriptional response to L. pneumophila. Furthermore, we find that uninfected macrophages treated with two different translation inhibitors exhibit activation of MAP kinases and upregulation of target genes, indicating that translation inhibition alone is sufficient to elicit this response in macrophages. MAP kinase pathways are crucial in many aspects of the immune response, including inflammation and cell motility. Our results demonstrate that this important host pathway can be activated in response to a pathogen-encoded activity, adding to an emerging body of evidence in support of this novel mode of innate immune detection in metazoans.
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Al-Quadan T, Price CT, Abu Kwaik Y. Exploitation of evolutionarily conserved amoeba and mammalian processes by Legionella. Trends Microbiol 2012; 20:299-306. [PMID: 22494803 DOI: 10.1016/j.tim.2012.03.005] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2011] [Revised: 02/29/2012] [Accepted: 03/13/2012] [Indexed: 01/09/2023]
Abstract
Legionella pneumophila proliferates within various protists and metazoan cells, where a cadre of ∼300 effectors is injected into the host cell by the defect in organelle trafficking/intracellular multiplication (Dot/Icm) type IVB translocation system. Interkingdom horizontal gene transfer of genes of protists and their subsequent convergent evolution to become translocated effectors has probably enabled L. pneumophila to adapt to the intracellular life within various protists and metazoan cells through exploitation of evolutionarily eukaryotic processes, such as endoplasmic reticulum-to-Golgi vesicle traffic, phosphoinositol metabolism, AMPylation, deAMPylation, prenylation, polyubiquitination, proteasomal degradation and cytosolic amino- and oligo-peptidases. This is highlighted by the ankyrin B (AnkB) F-box effector that exploits multiple conserved eukaryotic machineries to generate high levels of free amino acids as sources of carbon and energy essential for intracellular proliferation in protists and metazoan cells and for manifestation of pulmonary disease in mammals.
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Affiliation(s)
- Tasneem Al-Quadan
- Department of Microbiology and Immunology, College of Medicine, University of Louisville, Louisville, KY 40292, USA
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Rolando M, Buchrieser C. Post-translational modifications of host proteins by Legionella pneumophila: a sophisticated survival strategy. Future Microbiol 2012; 7:369-81. [DOI: 10.2217/fmb.12.9] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Eukaryotic proteins are tightly regulated by post-translational modifications, leading to a very subtle degree of regulation in time and space. Pathogen-mediated post-translational modifications are key strategies to modulate host factors by targeting central signaling pathways in the host cell. Legionella pneumophila, an intracellular pathogen that coevolved with protozoan hosts, encodes a large arsenal of secreted effectors conferring the ability to evade host cellular defenses and to manipulate them to promote invasion and intracellular replication. Conservation of many signaling pathways of protozoa in human macrophages confers the ability of L. pneumophila to infect humans, causing a severe pneumonia called legionnaires’ disease. Most of the secreted proteins are delivered by the Dot/Icm type IV secretion system and several of these have been shown to act on different cellular pathways critical for infection. Moreover, multiple effectors target a single host function to orchestrate bacterial survival. In this review, we focus on those effectors in the repertoire of L. pneumophila proteins that target key cellular pathways by specific post-translational modifications.
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Affiliation(s)
- Monica Rolando
- Institut Pasteur, Biologie des Bactéries Intracellulaires, 75724 Paris, France
- CNRS UMR 3525, 75724 Paris, France
| | - Carmen Buchrieser
- CNRS UMR 3525, 75724 Paris, France
- Institut Pasteur, Biologie des Bactéries Intracellulaires, 75724 Paris, France
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Abstract
Legionella pneumophila is a facultative intracellular pathogen capable of replicating in a wide spectrum of cells. Successful infection by Legionella requires the Dot/Icm type IV secretion system, which translocates a large number of effector proteins into infected cells. By co-opting numerous host cellular processes, these proteins function to establish a specialized organelle that allows bacterial survival and proliferation. Even within the vacuole, L. pneumophila triggers robust immune responses. Recent studies reveal that a subset of Legionella effectors directly target some basic components of the host innate immunity systems such as phagosome maturation. Others play essential roles in engaging the host innate immune surveillance system. This review will highlight recent progress in our understanding of these interactions and discuss implications for the study of the immune detection mechanisms.
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Affiliation(s)
- Zhao-Qing Luo
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA.
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Buchrieser C. Legionella: from protozoa to humans. Front Microbiol 2011; 2:182. [PMID: 22016745 PMCID: PMC3193031 DOI: 10.3389/fmicb.2011.00182] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2011] [Accepted: 08/18/2011] [Indexed: 11/13/2022] Open
Affiliation(s)
- Carmen Buchrieser
- Institut Pasteur, Biologie des Bactéries Intracellulaires and CNRS URA 2171 Paris, France
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