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Gazi AD, Kokkinidis M, Fadouloglou VE. α-Helices in the Type III Secretion Effectors: A Prevalent Feature with Versatile Roles. Int J Mol Sci 2021; 22:ijms22115412. [PMID: 34063760 PMCID: PMC8196651 DOI: 10.3390/ijms22115412] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 05/14/2021] [Accepted: 05/17/2021] [Indexed: 12/16/2022] Open
Abstract
Type III Secretion Systems (T3SSs) are multicomponent nanomachines located at the cell envelope of Gram-negative bacteria. Their main function is to transport bacterial proteins either extracellularly or directly into the eukaryotic host cell cytoplasm. Type III Secretion effectors (T3SEs), latest to be secreted T3S substrates, are destined to act at the eukaryotic host cell cytoplasm and occasionally at the nucleus, hijacking cellular processes through mimicking eukaryotic proteins. A broad range of functions is attributed to T3SEs, ranging from the manipulation of the host cell's metabolism for the benefit of the bacterium to bypassing the host's defense mechanisms. To perform this broad range of manipulations, T3SEs have evolved numerous novel folds that are compatible with some basic requirements: they should be able to easily unfold, pass through the narrow T3SS channel, and refold to an active form when on the other side. In this review, the various folds of T3SEs are presented with the emphasis placed on the functional and structural importance of α-helices and helical domains.
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Affiliation(s)
- Anastasia D. Gazi
- Unit of Technology & Service Ultrastructural Bio-Imaging (UTechS UBI), Institut Pasteur, 75015 Paris, France
- Correspondence: (A.D.G.); (V.E.F.)
| | - Michael Kokkinidis
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Nikolaou Plastira 100, Heraklion, 70013 Crete, Greece;
- Department of Biology, Voutes University Campus, University of Crete, Heraklion, 70013 Crete, Greece
| | - Vasiliki E. Fadouloglou
- Department of Molecular Biology & Genetics, Democritus University of Thrace, 68100 Alexandroupolis, Greece
- Correspondence: (A.D.G.); (V.E.F.)
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2
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Molecular Mechanisms That Define Redox Balance Function in Pathogen-Host Interactions-Is There a Role for Dietary Bioactive Polyphenols? Int J Mol Sci 2019; 20:ijms20246222. [PMID: 31835548 PMCID: PMC6940965 DOI: 10.3390/ijms20246222] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 12/02/2019] [Accepted: 12/03/2019] [Indexed: 01/01/2023] Open
Abstract
To ensure a functional immune system, the mammalian host must detect and respond to the presence of pathogenic bacteria during infection. This is accomplished in part by generating reactive oxygen species (ROS) that target invading bacteria; a process that is facilitated by NADPH oxidase upregulation. Thus, bacterial pathogens must overcome the oxidative burst produced by the host innate immune cells in order to survive and proliferate. In this way, pathogenic bacteria develop virulence, which is related to the affinity to secrete effector proteins against host ROS in order to facilitate microbial survival in the host cell. These effectors scavenge the host generated ROS directly, or alternatively, manipulate host cell signaling mechanisms designed to benefit pathogen survival. The redox-balance of the host is important for the regulation of cell signaling activities that include mitogen-activated protein kinase (MAPK), p21-activated kinase (PAK), phosphatidylinositol 3-kinase (PI3K)/Akt, and nuclear factor κB (NF-κB) pathways. An understanding of the function of pathogenic effectors to divert host cell signaling is important to ascertain the mechanisms underlying pathogen virulence and the eventual host–pathogen relationship. Herein, we examine the effectors produced by the microbial secretion system, placing emphasis on how they target molecular signaling mechanisms involved in a host immune response. Moreover, we discuss the potential impact of bioactive polyphenols in modulating these molecular interactions that will ultimately influence pathogen virulence.
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3
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Singh V, Davidson A, Hume PJ, Koronakis V. Pathogenic Escherichia coli Hijacks GTPase-Activated p21-Activated Kinase for Actin Pedestal Formation. mBio 2019; 10:e01876-19. [PMID: 31431554 PMCID: PMC6703428 DOI: 10.1128/mbio.01876-19] [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: 07/18/2019] [Accepted: 07/24/2019] [Indexed: 12/26/2022] Open
Abstract
Enteropathogenic Escherichia coli and enterohemorrhagic E. coli (EPEC and EHEC, respectively) are extracellular pathogens that reorganize the host cell cytoskeleton to form "actin pedestals" beneath the tightly adherent bacteria, a critical step in pathogenesis. EPEC and EHEC inject effector proteins that manipulate host cell signaling cascades to trigger pedestal assembly. One such effector, EspG, has been reported to bind and activate p21-activated kinase (PAK), a key cytoskeletal regulator, but the function of this interaction and whether it impacts pedestal assembly are unknown. Here, we demonstrate that deletion of espG significantly impairs pedestal formation and attachment by both EPEC and EHEC. This role of EspG is shown to be dependent on its interaction with PAK. Unexpectedly, EspG was able to subvert PAK only in the presence of Rho family small GTPases, which function to both concentrate PAK at the membrane and stimulate PAK activation. Our findings reveal a novel mechanism by which EspG hijacks PAK and sustains its active state to drive bacterial attachment to host cells.IMPORTANCE Enteropathogenic E. coli and enterohemorrhagic E. coli (EPEC and EHEC, respectively) remain a significant global health problem. Both EPEC and EHEC initiate infection by attaching to cells in the host intestine, triggering the formation of actin-rich "pedestal" structures directly beneath the adherent pathogen. These bacteria inject their own receptor into host cells, which upon binding to a protein on the pathogen surface triggers pedestal formation. Multiple other proteins are also delivered into the cells of the host intestine, but how they contribute to disease is often less clear. Here, we show how one of these injected proteins, EspG, hijacks a host signaling pathway for pedestal production. This provides new insights into this essential early stage in EPEC and EHEC disease.
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Affiliation(s)
- Vikash Singh
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Anthony Davidson
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Peter J Hume
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
| | - Vassilis Koronakis
- Department of Pathology, University of Cambridge, Cambridge, United Kingdom
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4
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Tapia R, Kralicek SE, Hecht GA. Modulation of epithelial cell polarity by bacterial pathogens. Ann N Y Acad Sci 2017. [PMID: 28628193 DOI: 10.1111/nyas.13388] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Epithelial cells constitute a physical barrier that aids in protecting the host from microbial pathogens. Polarized epithelial cells contain distinct apical and basolateral membrane domains separated by intercellular junctions, including tight junctions (TJs), which contribute to the maintenance of apical-basal polarity. Polarity complexes also contribute to the establishment of TJ formation. Several pathogens perturb epithelial TJ barrier function and structure in addition to causing a loss of apical-basal polarity. Here, we review the impact of pathogenic bacteria on the disruption of cell-cell junctions and epithelial polarity.
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Affiliation(s)
- Rocio Tapia
- Division of Gastroenterology and Nutrition, Department of Medicine, Loyola University Chicago, Maywood, Illinois
| | - Sarah E Kralicek
- Division of Gastroenterology and Nutrition, Department of Medicine, Loyola University Chicago, Maywood, Illinois
| | - Gail A Hecht
- Division of Gastroenterology and Nutrition, Department of Medicine, Loyola University Chicago, Maywood, Illinois.,Department of Microbiology and Immunology, Loyola University Chicago, Maywood, Illinois.,Edward Hines Jr. VA Hospital, Hines, Illinois
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5
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John Von Freyend S, Kwok-Schuelein T, Netter HJ, Haqshenas G, Semblat JP, Doerig C. Subverting Host Cell P21-Activated Kinase: A Case of Convergent Evolution across Pathogens. Pathogens 2017; 6:pathogens6020017. [PMID: 28430160 PMCID: PMC5488651 DOI: 10.3390/pathogens6020017] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Revised: 03/29/2017] [Accepted: 04/09/2017] [Indexed: 12/14/2022] Open
Abstract
Intracellular pathogens have evolved a wide range of strategies to not only escape from the immune systems of their hosts, but also to directly exploit a variety of host factors to facilitate the infection process. One such strategy is to subvert host cell signalling pathways to the advantage of the pathogen. Recent research has highlighted that the human serine/threonine kinase PAK, or p21-activated kinase, is a central component of host-pathogen interactions in many infection systems involving viruses, bacteria, and eukaryotic pathogens. PAK paralogues are found in most mammalian tissues, where they play vital roles in a wide range of functions. The role of PAKs in cell proliferation and survival, and their involvement in a number of cancers, is of great interest in the context of drug discovery. In this review we discuss the latest insights into the surprisingly central role human PAK1 plays for the infection by such different infectious disease agents as viruses, bacteria, and parasitic protists. It is our intention to open serious discussion on the applicability of PAK inhibitors for the treatment, not only of neoplastic diseases, which is currently the primary objective of drug discovery research targeting these enzymes, but also of a wide range of infectious diseases.
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Affiliation(s)
- Simona John Von Freyend
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Melbourne, Victoria 3800, Australia.
| | - Terry Kwok-Schuelein
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Melbourne, Victoria 3800, Australia.
- Cancer Program, Monash Biomedicine Discovery Institute, Department of Biochemistry and Molecular Biology, Monash University, Melbourne, Victoria 3800, Australia.
| | - Hans J Netter
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Melbourne, Victoria 3800, Australia.
- Victorian Infectious Diseases Reference Laboratory, Melbourne Health, The Peter Doherty Institute, Melbourne, Victoria 3000, Australia.
| | - Gholamreza Haqshenas
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Melbourne, Victoria 3800, Australia.
| | | | - Christian Doerig
- Infection and Immunity Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Melbourne, Victoria 3800, Australia.
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6
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Humphreys D, Singh V, Koronakis V. Inhibition of WAVE Regulatory Complex Activation by a Bacterial Virulence Effector Counteracts Pathogen Phagocytosis. Cell Rep 2016; 17:697-707. [PMID: 27732847 PMCID: PMC5081413 DOI: 10.1016/j.celrep.2016.09.039] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Revised: 06/24/2016] [Accepted: 09/14/2016] [Indexed: 02/05/2023] Open
Abstract
To establish pathogenicity, bacteria must evade phagocytosis directed by remodeling of the actin cytoskeleton. We show that macrophages facilitate pathogen phagocytosis through actin polymerization mediated by the WAVE regulatory complex (WRC), small GTPases Arf and Rac1, and the Arf1 activator ARNO. To establish extracellular infections, enteropathogenic (EPEC) and enterohaemorrhagic (EHEC) Escherichia coli hijack the actin cytoskeleton by injecting virulence effectors into the host cell. Here, we find that the virulence effector EspG counteracts WRC-dependent phagocytosis, enabling EPEC and EHEC to remain extracellular. By reconstituting membrane-associated actin polymerization, we find that EspG disabled WRC activation through two mechanisms: EspG interaction with Arf6 blocked signaling to ARNO while EspG binding of Arf1 impeded collaboration with Rac1, thereby inhibiting WRC recruitment and activation. Investigating the mode of EspG interference revealed sites in Arf1 required for WRC activation and a mechanism facilitating pathogen evasion of innate host defenses.
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Affiliation(s)
- Daniel Humphreys
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK.
| | - Vikash Singh
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK
| | - Vassilis Koronakis
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK.
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7
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Ugalde-Silva P, Gonzalez-Lugo O, Navarro-Garcia F. Tight Junction Disruption Induced by Type 3 Secretion System Effectors Injected by Enteropathogenic and Enterohemorrhagic Escherichia coli. Front Cell Infect Microbiol 2016; 6:87. [PMID: 27606286 PMCID: PMC4995211 DOI: 10.3389/fcimb.2016.00087] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Accepted: 08/10/2016] [Indexed: 12/18/2022] Open
Abstract
The intestinal epithelium consists of a single cell layer, which is a critical selectively permeable barrier to both absorb nutrients and avoid the entry of potentially harmful entities, including microorganisms. Epithelial cells are held together by the apical junctional complexes, consisting of adherens junctions, and tight junctions (TJs), and by underlying desmosomes. TJs lay in the apical domain of epithelial cells and are mainly composed by transmembrane proteins such as occludin, claudins, JAMs, and tricellulin, that are associated with the cytoplasmic plaque formed by proteins from the MAGUK family, such as ZO-1/2/3, connecting TJ to the actin cytoskeleton, and cingulin and paracingulin connecting TJ to the microtubule network. Extracellular bacteria such as EPEC and EHEC living in the intestinal lumen inject effectors proteins directly from the bacterial cytoplasm to the host cell cytoplasm, where they play a relevant role in the manipulation of the eukaryotic cell functions by modifying or blocking cell signaling pathways. TJ integrity depends on various cell functions such as actin cytoskeleton, microtubule network for vesicular trafficking, membrane integrity, inflammation, and cell survival. EPEC and EHEC effectors target most of these functions. Effectors encoded inside or outside of locus of enterocyte effacement (LEE) disrupt the TJ strands. EPEC and EHEC exploit the TJ dynamics to open this structure, for causing diarrhea. EPEC and EHEC secrete effectors that mimic host proteins to manipulate the signaling pathways, including those related to TJ dynamics. In this review, we focus on the known mechanisms exploited by EPEC and EHEC effectors for causing TJ disruption.
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Affiliation(s)
- Paul Ugalde-Silva
- Department of Cell Biology, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional México City, Mexico
| | - Octavio Gonzalez-Lugo
- Department of Cell Biology, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional México City, Mexico
| | - Fernando Navarro-Garcia
- Department of Cell Biology, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional México City, Mexico
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8
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Enterohaemorrhagic E. coli modulates an ARF6:Rab35 signaling axis to prevent recycling endosome maturation during infection. J Mol Biol 2016; 428:3399-407. [PMID: 27261256 PMCID: PMC5013874 DOI: 10.1016/j.jmb.2016.05.023] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 05/19/2016] [Accepted: 05/20/2016] [Indexed: 02/06/2023]
Abstract
Enteropathogenic and enterohaemorrhagic Escherichia coli (EPEC/EHEC) manipulate a plethora of host cell processes to establish infection of the gut mucosa. This manipulation is achieved via the injection of bacterial effector proteins into host cells using a Type III secretion system. We have previously reported that the conserved EHEC and EPEC effector EspG disrupts recycling endosome function, reducing cell surface levels of host receptors through accumulation of recycling cargo within the host cell. Here we report that EspG interacts specifically with the small GTPases ARF6 and Rab35 during infection. These interactions target EspG to endosomes and prevent Rab35-mediated recycling of cargo to the host cell surface. Furthermore, we show that EspG has no effect on Rab35-mediated uncoating of newly formed endosomes, and instead leads to the formation of enlarged EspG/TfR/Rab11 positive, EEA1/Clathrin negative stalled recycling structures. Thus, this paper provides a molecular framework to explain how EspG disrupts recycling whilst also reporting the first known simultaneous targeting of ARF6 and Rab35 by a bacterial pathogen. EHEC delivers effector proteins into host cells to establish infection in the gut The effector EspG interacts with GTP-ARF6 confining EspG to recycling endosomes During infection EspG interacts preferentially with Rab35, not Rab1 Spatial restriction of bacterial effectors during infection determines their function
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9
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The Locus of Enterocyte Effacement and Associated Virulence Factors of Enterohemorrhagic Escherichia coli. Microbiol Spectr 2016; 2:EHEC-0007-2013. [PMID: 26104209 DOI: 10.1128/microbiolspec.ehec-0007-2013] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A subset of Shiga toxin-producing Escherichia coli strains, termed enterohemorrhagic E. coli (EHEC), is defined in part by the ability to produce attaching and effacing (A/E) lesions on intestinal epithelia. Such lesions are characterized by intimate bacterial attachment to the apical surface of enterocytes, cytoskeletal rearrangements beneath adherent bacteria, and destruction of proximal microvilli. A/E lesion formation requires the locus of enterocyte effacement (LEE), which encodes a Type III secretion system that injects bacterial proteins into host cells. The translocated proteins, termed effectors, subvert a plethora of cellular pathways to the benefit of the pathogen, for example, by recruiting cytoskeletal proteins, disrupting epithelial barrier integrity, and interfering with the induction of inflammation, phagocytosis, and apoptosis. The LEE and selected effectors play pivotal roles in intestinal persistence and virulence of EHEC, and it is becoming clear that effectors may act in redundant, synergistic, and antagonistic ways during infection. Vaccines that target the function of the Type III secretion system limit colonization of reservoir hosts by EHEC and may thus aid control of zoonotic infections. Here we review the features and functions of the LEE-encoded Type III secretion system and associated effectors of E. coli O157:H7 and other Shiga toxin-producing E. coli strains.
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10
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Singh AP, Aijaz S. Enteropathogenic E. coli: breaking the intestinal tight junction barrier. F1000Res 2015; 4:231. [DOI: 10.12688/f1000research.6778.1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 07/09/2015] [Indexed: 11/20/2022] Open
Abstract
Enteropathogenic E. coli (EPEC) causes acute intestinal infections in infants in the developing world. Infection typically spreads through contaminated food and water and leads to severe, watery diarrhea. EPEC attaches to the intestinal epithelial cells and directly injects virulence factors which modulate multiple signaling pathways leading to host cell dysfunction. However, the molecular mechanisms that regulate the onset of diarrhea are poorly defined. A major target of EPEC is the host cell tight junction complex which acts as a barrier and regulates the passage of water and solutes through the paracellular space. In this review, we focus on the EPEC effectors that target the epithelial barrier, alter its functions and contribute to leakage through the tight junctions.
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11
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Abstract
Enteropathogenic
E. coli (EPEC) causes acute intestinal infections in infants in the developing world. Infection typically spreads through contaminated food and water and leads to severe, watery diarrhea. EPEC attaches to the intestinal epithelial cells and directly injects virulence factors which modulate multiple signaling pathways leading to host cell dysfunction. However, the molecular mechanisms that regulate the onset of diarrhea are poorly defined. A major target of EPEC is the host cell tight junction complex which acts as a barrier and regulates the passage of water and solutes through the paracellular space. In this review, we focus on the EPEC effectors that target the epithelial barrier, alter its functions and contribute to leakage through the tight junctions.
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Affiliation(s)
- Anand Prakash Singh
- Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, 110067, India
| | - Saima Aijaz
- Centre for Molecular Medicine, Jawaharlal Nehru University, New Delhi, 110067, India
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12
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Dammann K, Khare V, Gasche C. Republished: tracing PAKs from GI inflammation to cancer. Postgrad Med J 2014; 90:657-68. [PMID: 25335797 PMCID: PMC4222351 DOI: 10.1136/postgradmedj-2014-306768rep] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Revised: 04/07/2014] [Accepted: 04/10/2014] [Indexed: 12/20/2022]
Abstract
P-21 activated kinases (PAKs) are effectors of Rac1/Cdc42 which coordinate signals from the cell membrane to the nucleus. Activation of PAKs drive important signalling pathways including mitogen activated protein kinase, phospoinositide 3-kinase (PI3K/AKT), NF-κB and Wnt/β-catenin. Intestinal PAK1 expression increases with inflammation and malignant transformation, although the biological relevance of PAKs in the development and progression of GI disease is only incompletely understood. This review highlights the importance of altered PAK activation within GI inflammation, emphasises its effect on oncogenic signalling and discusses PAKs as therapeutic targets of chemoprevention.
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Affiliation(s)
- Kyle Dammann
- Department of Medicine III, Division of Gastroenterology and Hepatology and Christian Doppler Laboratory for Molecular Cancer Chemoprevention, Medical University of Vienna, Vienna, Austria
| | - Vineeta Khare
- Department of Medicine III, Division of Gastroenterology and Hepatology and Christian Doppler Laboratory for Molecular Cancer Chemoprevention, Medical University of Vienna, Vienna, Austria
| | - Christoph Gasche
- Department of Medicine III, Division of Gastroenterology and Hepatology and Christian Doppler Laboratory for Molecular Cancer Chemoprevention, Medical University of Vienna, Vienna, Austria
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13
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Glotfelty LG, Zahs A, Hodges K, Shan K, Alto NM, Hecht GA. Enteropathogenic E. coli effectors EspG1/G2 disrupt microtubules, contribute to tight junction perturbation and inhibit restoration. Cell Microbiol 2014; 16:1767-83. [PMID: 24948117 DOI: 10.1111/cmi.12323] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2013] [Revised: 05/20/2014] [Accepted: 06/05/2014] [Indexed: 12/14/2022]
Abstract
Enteropathogenic Escherichia coli (EPEC) uses a type 3 secretion system to transfer effector proteins into the host intestinal epithelial cell. Several effector molecules contribute to tight junction disruption including EspG1 and its homologue EspG2 via a mechanism thought to involve microtubule destruction. The aim of this study was to investigate the contribution of EspG-mediated microtubule disruption to TJ perturbation. We demonstrate that wild type EPEC infection disassembles microtubules and induces the progressive movement of occludin away from the membrane and into the cytosol. Deletion of espG1/G2 attenuates both of these phenotypes. In addition, EPEC infection impedes barrier recovery from calcium switch, suggesting that inhibition of TJ restoration, not merely disruption, prolongs barrier loss. TJs recover more rapidly following infection with ΔespG1/G2 than with wild type EPEC, demonstrating that EspG1/G2 perpetuate barrier loss. Although EspG regulates ADP-ribosylation factor (ARF) and p21-activated kinase (PAK), these activities are not necessary for microtubule destruction or perturbation of TJ structure and function. These data strongly support a role for EspG1/G2 and its associated effects on microtubules in delaying the recovery of damaged tight junctions caused by EPEC infection.
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Affiliation(s)
- Lila G Glotfelty
- Department of Microbiology & Immunology, University of Illinois at Chicago, 835 S. Wolcott, (M/C 790), Chicago, IL, 60612, USA
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14
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Clements A, Stoneham CA, Furniss RCD, Frankel G. Enterohaemorrhagic Escherichia coli inhibits recycling endosome function and trafficking of surface receptors. Cell Microbiol 2014; 16:1693-705. [PMID: 24898821 PMCID: PMC4336558 DOI: 10.1111/cmi.12319] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2014] [Revised: 05/23/2014] [Accepted: 05/28/2014] [Indexed: 01/26/2023]
Abstract
Enteropathogenic and enterohaemorrhagic Escherichia coli (EPEC/EHEC) manipulate many cell processes by injecting effector proteins from the bacteria into the host cell via a Type III secretion system. In this paper we report that the effector protein EspG disrupts recycling endosome function. In particular, we found that following transferrin binding and endocytosis EspG reduces recycling of the transferrin receptor (TfR), the prototypical recycling protein, from an intracellular location to the cell surface, resulting in an accumulation of TfR within the cell. The surface levels of three receptors [TfR, epidermal growth factor receptor (EGFR) and β1 integrin] were tested and found to be reduced dependent on EspG translocation. Furthermore, disruption of recycling endosome function and the reduced surface presentation of receptors was dependent on the previously reported RabGAP activity and ARF binding ability of EspG. This paper therefore supports the previous hypothesis that EspG acts as an enzyme scaffold perturbing cell signalling events, in this case altering recycling endosome function and cell surface receptor levels during infection.
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Affiliation(s)
- Abigail Clements
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College, London, UK
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15
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Abstract
P-21 activated kinases (PAKs) are effectors of Rac1/Cdc42 which coordinate signals from the cell membrane to the nucleus. Activation of PAKs drive important signalling pathways including mitogen activated protein kinase, phospoinositide 3-kinase (PI3K/AKT), NF-κB and Wnt/β-catenin. Intestinal PAK1 expression increases with inflammation and malignant transformation, although the biological relevance of PAKs in the development and progression of GI disease is only incompletely understood. This review highlights the importance of altered PAK activation within GI inflammation, emphasises its effect on oncogenic signalling and discusses PAKs as therapeutic targets of chemoprevention.
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Affiliation(s)
- Kyle Dammann
- Department of Medicine III, Division of Gastroenterology and Hepatology and Christian Doppler Laboratory for Molecular Cancer Chemoprevention, Medical University of Vienna, Vienna, Austria
| | - Vineeta Khare
- Department of Medicine III, Division of Gastroenterology and Hepatology and Christian Doppler Laboratory for Molecular Cancer Chemoprevention, Medical University of Vienna, Vienna, Austria
| | - Christoph Gasche
- Department of Medicine III, Division of Gastroenterology and Hepatology and Christian Doppler Laboratory for Molecular Cancer Chemoprevention, Medical University of Vienna, Vienna, Austria
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16
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Jayamani E, Mylonakis E. Effector triggered manipulation of host immune response elicited by different pathotypes of Escherichia coli. Virulence 2014; 5:733-9. [PMID: 25513774 PMCID: PMC4189879 DOI: 10.4161/viru.29948] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2014] [Revised: 07/08/2014] [Accepted: 07/15/2014] [Indexed: 12/28/2022] Open
Abstract
Effectors are virulence factors that are secreted by bacteria during an infection in order to subvert cellular processes or induce the surveillance system of the host. Pathogenic microorganisms encode effectors, toxins and components of secretion systems that inject the effectors to the host. Escherichia coli is part of the innocuous commensal microbial flora of the gastrointestinal tract. However, pathogenic E. coli can cause diarrheal and extraintestinal diseases. Pathogenic E. coli uses secretion systems to inject an array of effector proteins directly into the host cells. Herein, we discuss the effectors secreted by different pathotypes of E. coli and provide an overview of strategies employed by effectors to target the host cellular and subcellular processes as well as their role in triggering host immune response.
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Affiliation(s)
- Elamparithi Jayamani
- Division of Infectious Diseases; Rhode Island Hospital; Alpert Medical School of Brown University; Providence, RI USA
| | - Eleftherios Mylonakis
- Division of Infectious Diseases; Rhode Island Hospital; Alpert Medical School of Brown University; Providence, RI USA
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17
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Subversion of trafficking, apoptosis, and innate immunity by type III secretion system effectors. Trends Microbiol 2013; 21:430-41. [DOI: 10.1016/j.tim.2013.06.008] [Citation(s) in RCA: 100] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Revised: 05/08/2013] [Accepted: 06/18/2013] [Indexed: 11/17/2022]
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Actin cytoskeleton manipulation by effector proteins secreted by diarrheagenic Escherichia coli pathotypes. BIOMED RESEARCH INTERNATIONAL 2012; 2013:374395. [PMID: 23509714 PMCID: PMC3591105 DOI: 10.1155/2013/374395] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/24/2012] [Accepted: 10/22/2012] [Indexed: 11/18/2022]
Abstract
The actin cytoskeleton is a dynamic structure necessary for cell and tissue organization, including the maintenance of epithelial barriers. Disruption of the epithelial barrier coincides with alterations of the actin cytoskeleton in several disease states. These disruptions primarily affect the paracellular space, which is normally regulated by tight junctions. Thereby, the actin cytoskeleton is a common and recurring target of bacterial virulence factors. In order to manipulate the actin cytoskeleton, bacteria secrete and inject toxins and effectors to hijack the host cell machinery, which interferes with host-cell pathways and with a number of actin binding proteins. An interesting model to study actin manipulation by bacterial effectors is Escherichia coli since due to its genome plasticity it has acquired diverse genetic mobile elements, which allow having different E. coli varieties in one bacterial species. These E. coli pathotypes, including intracellular and extracellular bacteria, interact with epithelial cells, and their interactions depend on a specific combination of virulence factors. In this paper we focus on E. coli effectors that mimic host cell proteins to manipulate the actin cytoskeleton. The study of bacterial effector-cytoskeleton interaction will contribute not only to the comprehension of the molecular causes of infectious diseases but also to increase our knowledge of cell biology.
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Dong N, Zhu Y, Lu Q, Hu L, Zheng Y, Shao F. Structurally distinct bacterial TBC-like GAPs link Arf GTPase to Rab1 inactivation to counteract host defenses. Cell 2012; 150:1029-41. [PMID: 22939626 DOI: 10.1016/j.cell.2012.06.050] [Citation(s) in RCA: 168] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2011] [Revised: 02/15/2012] [Accepted: 06/29/2012] [Indexed: 11/25/2022]
Abstract
Rab GTPases are frequent targets of vacuole-living bacterial pathogens for appropriate trafficking of the vacuole. Here we discover that bacterial effectors including VirA from nonvacuole Shigella flexneri and EspG from extracellular Enteropathogenic Escherichia coli (EPEC) harbor TBC-like dual-finger motifs and exhibits potent RabGAP activities. Specific inactivation of Rab1 by VirA/EspG disrupts ER-to-Golgi trafficking. S. flexneri intracellular persistence requires VirA TBC-like GAP activity that mediates bacterial escape from autophagy-mediated host defense. Rab1 inactivation by EspG severely blocks host secretory pathway, resulting in inhibited interleukin-8 secretion from infected cells. Crystal structures of VirA/EspG-Rab1-GDP-aluminum fluoride complexes highlight TBC-like catalytic role for the arginine and glutamine finger residues and reveal a 3D architecture distinct from that of the TBC domain. Structure of Arf6-EspG-Rab1 ternary complex illustrates a pathogenic signaling complex that rewires host Arf signaling to Rab1 inactivation. Structural distinctions of VirA/EspG further predict a possible extensive presence of TBC-like RabGAP effectors in counteracting various host defenses.
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Affiliation(s)
- Na Dong
- National Institute of Biological Sciences, Beijing 102206, China
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Glotfelty LG, Hecht GA. Enteropathogenic E. coli effectors EspG1/G2 disrupt tight junctions: new roles and mechanisms. Ann N Y Acad Sci 2012; 1258:149-58. [PMID: 22731728 DOI: 10.1111/j.1749-6632.2012.06563.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Enteropathogenic E. coli (EPEC) infection is a major cause of infantile diarrhea in the developing world. Using a type-three secretion system, bacterial effector proteins are transferred to the host cell cytosol where they affect multiple physiological functions, ultimately leading to diarrheal disease. Disruption of intestinal epithelial cell tight junctions is a major consequence of EPEC infection and is mediated by multiple effector proteins, among them EspG1 and its homologue EspG2. EspG1/G2 contribute to loss of barrier function via an undefined mechanism that may be linked to their disruption of microtubule networks. Recently new investigations have identified additional roles for EspG. Sequestration of active ADP-ribosylating factor (ARF) proteins and promotion of p21-activated kinase (PAK) activity as well as inhibition of Golgi-mediated protein secretion have all been linked to EspG. In this review, we examine the functions of EspG1/G2 and discuss potential mechanisms of EspG-mediated tight junction disruption.
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Affiliation(s)
- Lila G Glotfelty
- Section of Digestive Diseases and Nutrition, Department of Medicine, University of Illinois at Chicago, Chicago, Illinois, USA
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21
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Krachler AM, Woolery AR, Orth K. Manipulation of kinase signaling by bacterial pathogens. ACTA ACUST UNITED AC 2011; 195:1083-92. [PMID: 22123833 PMCID: PMC3246894 DOI: 10.1083/jcb.201107132] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Bacterial pathogens use effector proteins to manipulate their hosts to propagate infection. These effectors divert host cell signaling pathways to the benefit of the pathogen and frequently target kinase signaling cascades. Notable pathways that are usurped include the nuclear factor κB (NF-κB), mitogen-activated protein kinase (MAPK), phosphatidylinositol 3-kinase (PI3K)/Akt, and p21-activated kinase (PAK) pathways. Analyzing the functions of pathogenic effectors and their intersection with host kinase pathways has provided interesting insights into both the mechanisms of virulence and eukaryotic signaling.
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Affiliation(s)
- Anne Marie Krachler
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
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22
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Cui J, Shao F. Biochemistry and cell signaling taught by bacterial effectors. Trends Biochem Sci 2011; 36:532-40. [DOI: 10.1016/j.tibs.2011.07.003] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2011] [Revised: 07/08/2011] [Accepted: 07/18/2011] [Indexed: 12/22/2022]
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23
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Clements A, Smollett K, Lee SF, Hartland EL, Lowe M, Frankel G. EspG of enteropathogenic and enterohemorrhagic E. coli binds the Golgi matrix protein GM130 and disrupts the Golgi structure and function. Cell Microbiol 2011; 13:1429-39. [PMID: 21740499 DOI: 10.1111/j.1462-5822.2011.01631.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
The enteric pathogens enteropathogenic Escherichia coli (EPEC), enterohaemorrhagic E. coli (EHEC) and Shigella flexneri all translocate at least one effector protein of the EspG protein family into host cells via a type III secretion system (T3SS). The EspG family comprises EspG, EspG2 and VirA. From a Y2H screen, we identified the Golgi matrix protein GM130 as a potential binding partner of EspG. We confirmed EspG:GM130 protein interaction by affinity co-purification. In co-immunoprecipitation experiments EspG was co-precipitated with GM130 while both GM130 and tubulins were co-precipitated with EspG. When expressed ectopically in HeLa cells, the EspG protein family all localized to the Golgi and induced fragmentation of the Golgi apparatus. All EspG family proteins were also able to disrupt protein secretion to a greater extent than the T3SS effector NleA/EspI, which has previously been shown to localize to the Golgi and interact with SEC24 to disrupt COPII vesicle formation. We hypothesize that EspG:GM130 interaction disrupts protein secretion either through direct disruption of GM130 function or through recruitment of other EspG interacting proteins to the Golgi.
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Affiliation(s)
- Abigail Clements
- Centre for Molecular Microbiology and Infection, Imperial College, London SW7 2AZ, UK
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Lesser CF, Leong JM. Bacterial scaffolds assemble novel higher-order complexes to reengineer eukaryotic cell processes. Sci Signal 2011; 4:pe32. [PMID: 21730324 DOI: 10.1126/scisignal.2002252] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Many microbial pathogens use specialized secretion systems to inject proteins referred to as effectors directly into eukaryotic host cells. These effectors directly target various eukaryotic signaling pathways and cellular processes, often by mimicking the activity of host cell proteins. Effectors of pathogenic Escherichia coli and Salmonella typhimurium can also act as molecular scaffolds that not only recruit but also directly regulate the activity and localization of multiple eukaryotic proteins. By assembling and localizing disparate signaling pathways, the bacteria can reengineer host cell processes to generate novel processes not previously observed in eukaryotic cells.
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Affiliation(s)
- Cammie F Lesser
- Department of Medicine (Microbiology and Molecular Genetics), Division of Infectious Diseases, Massachusetts General Hospital and Harvard Medical School, 65 Landsdowne Street, Cambridge, MA 02139, USA.
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25
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Wong ARC, Pearson JS, Bright MD, Munera D, Robinson KS, Lee SF, Frankel G, Hartland EL. Enteropathogenic and enterohaemorrhagic Escherichia coli: even more subversive elements. Mol Microbiol 2011; 80:1420-38. [PMID: 21488979 DOI: 10.1111/j.1365-2958.2011.07661.x] [Citation(s) in RCA: 253] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Affiliation(s)
- Alexander R C Wong
- Centre for Molecular Microbiology and Infection, Division of Cell and Molecular Biology, Imperial College London, London SW7 2AZ, UK
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