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Chen T, Pu M, Subramanian S, Kearns D, Rowe-Magnus D. PlzD modifies Vibrio vulnificus foraging behavior and virulence in response to elevated c-di-GMP. mBio 2023; 14:e0153623. [PMID: 37800901 PMCID: PMC10653909 DOI: 10.1128/mbio.01536-23] [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: 06/23/2023] [Accepted: 08/21/2023] [Indexed: 10/07/2023] Open
Abstract
IMPORTANCE Many free-swimming bacteria propel themselves through liquid using rotary flagella, and mounting evidence suggests that the inhibition of flagellar rotation initiates biofilm formation, a sessile lifestyle that is a nearly universal surface colonization paradigm in bacteria. In general, motility and biofilm formation are inversely regulated by the intracellular second messenger bis-(3´-5´)-cyclic dimeric guanosine monophosphate (c-di-GMP). Here, we identify a protein, PlzD, bearing a conserved c-di-GMP binding PilZ domain that localizes to the flagellar pole in a c-di-GMP-dependent manner and alters the foraging behavior, biofilm, and virulence characteristics of the opportunistic human pathogen, Vibrio vulnificus. Our data suggest that PlzD interacts with components of the flagellar stator to decrease bacterial swimming speed and changes in swimming direction, and these activities are enhanced when cellular c-di-GMP levels are elevated. These results reveal a physical link between a second messenger (c-di-GMP) and an effector (PlzD) that promotes transition from a motile to a sessile state in V. vulnificus.
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Affiliation(s)
- Tianyi Chen
- Department of Biology, Indiana University Bloomington, Bloomington, Indiana, USA
| | - Meng Pu
- Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota, USA
| | - Sundharraman Subramanian
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, USA
| | - Dan Kearns
- Department of Biology, Indiana University Bloomington, Bloomington, Indiana, USA
| | - Dean Rowe-Magnus
- Department of Biology, Indiana University Bloomington, Bloomington, Indiana, USA
- Department of Molecular and Cellular Biochemistry, Indiana University Bloomington, Bloomington, Indiana, USA
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2
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Pillay TD, Hettiarachchi SU, Gan J, Diaz-Del-Olmo I, Yu XJ, Muench JH, Thurston TL, Pearson JS. Speaking the host language: how Salmonella effector proteins manipulate the host. MICROBIOLOGY (READING, ENGLAND) 2023; 169:001342. [PMID: 37279149 PMCID: PMC10333799 DOI: 10.1099/mic.0.001342] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/18/2023] [Accepted: 05/10/2023] [Indexed: 06/08/2023]
Abstract
Salmonella injects over 40 virulence factors, termed effectors, into host cells to subvert diverse host cellular processes. Of these 40 Salmonella effectors, at least 25 have been described as mediating eukaryotic-like, biochemical post-translational modifications (PTMs) of host proteins, altering the outcome of infection. The downstream changes mediated by an effector's enzymatic activity range from highly specific to multifunctional, and altogether their combined action impacts the function of an impressive array of host cellular processes, including signal transduction, membrane trafficking, and both innate and adaptive immune responses. Salmonella and related Gram-negative pathogens have been a rich resource for the discovery of unique enzymatic activities, expanding our understanding of host signalling networks, bacterial pathogenesis as well as basic biochemistry. In this review, we provide an up-to-date assessment of host manipulation mediated by the Salmonella type III secretion system injectosome, exploring the cellular effects of diverse effector activities with a particular focus on PTMs and the implications for infection outcomes. We also highlight activities and functions of numerous effectors that remain poorly characterized.
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Affiliation(s)
- Timesh D. Pillay
- Centre for Bacterial Resistance Biology, Department of Infectious Disease, Imperial College, London SW7 2AZ, UK
- The Francis Crick Institute, London NW1 1AT, UK
| | - Sahampath U. Hettiarachchi
- Centre for Innate Immunity and Infectious Diseases, Hudson Institute of Medical Research, Clayton, Victoria, Australia
- Department of Microbiology, Monash University, Clayton, Victoria, Australia
| | - Jiyao Gan
- Centre for Innate Immunity and Infectious Diseases, Hudson Institute of Medical Research, Clayton, Victoria, Australia
| | - Ines Diaz-Del-Olmo
- Centre for Bacterial Resistance Biology, Department of Infectious Disease, Imperial College, London SW7 2AZ, UK
| | - Xiu-Jun Yu
- Centre for Bacterial Resistance Biology, Department of Infectious Disease, Imperial College, London SW7 2AZ, UK
| | - Janina H. Muench
- Centre for Bacterial Resistance Biology, Department of Infectious Disease, Imperial College, London SW7 2AZ, UK
- The Francis Crick Institute, London NW1 1AT, UK
| | - Teresa L.M. Thurston
- Centre for Bacterial Resistance Biology, Department of Infectious Disease, Imperial College, London SW7 2AZ, UK
- The Francis Crick Institute, London NW1 1AT, UK
| | - Jaclyn S. Pearson
- Centre for Innate Immunity and Infectious Diseases, Hudson Institute of Medical Research, Clayton, Victoria, Australia
- Department of Microbiology, Monash University, Clayton, Victoria, Australia
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3
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Ciaston I, Dobosz E, Potempa J, Koziel J. The subversion of toll-like receptor signaling by bacterial and viral proteases during the development of infectious diseases. Mol Aspects Med 2022; 88:101143. [PMID: 36152458 PMCID: PMC9924004 DOI: 10.1016/j.mam.2022.101143] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Revised: 07/29/2022] [Accepted: 09/09/2022] [Indexed: 02/05/2023]
Abstract
Toll-like receptors (TLRs) are pattern recognition receptors (PRRs) that respond to pathogen-associated molecular patterns (PAMPs). The recognition of specific microbial ligands by TLRs triggers an innate immune response and also promotes adaptive immunity, which is necessary for the efficient elimination of invading pathogens. Successful pathogens have therefore evolved strategies to subvert and/or manipulate TLR signaling. Both the impairment and uncontrolled activation of TLR signaling can harm the host, causing tissue destruction and allowing pathogens to proliferate, thus favoring disease progression. In this context, microbial proteases are key virulence factors that modify components of the TLR signaling pathway. In this review, we discuss the role of bacterial and viral proteases in the manipulation of TLR signaling, highlighting the importance of these enzymes during the development of infectious diseases.
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Affiliation(s)
- Izabela Ciaston
- Department of Microbiology Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland
| | - Ewelina Dobosz
- Department of Microbiology Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland
| | - Jan Potempa
- Department of Microbiology Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland; Department of Oral Health and Systemic Disease, University of Louisville School of Dentistry, University of Louisville, Louisville, KY, USA.
| | - Joanna Koziel
- Department of Microbiology Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University, Krakow, Poland.
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Bline KE, Hall MW. Immune Function in Critically Ill Septic Children. Pathogens 2021; 10:1239. [PMID: 34684188 PMCID: PMC8539782 DOI: 10.3390/pathogens10101239] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2021] [Revised: 09/13/2021] [Accepted: 09/22/2021] [Indexed: 11/19/2022] Open
Abstract
The inflammatory response in pediatric sepsis is highly dynamic and includes both pro- and anti-inflammatory elements that involve the innate and adaptive immune systems. While the pro-inflammatory response is responsible for the initial clinical signs and symptoms of sepsis, a concurrent compensatory anti-inflammatory response often results in an occult, but highly clinically relevant, form of acquired immunodeficiency. When severe, this is termed "immunoparalysis" and is associated with increased risks for nosocomial infection, prolonged organ dysfunction, and death. This review focuses on the pathophysiology and clinical implications of both over- and under-active immune function in septic children. Host-, disease-, and treatment-specific risk factors for immunoparalysis are reviewed along with immune phenotype-specific approaches for immunomodulation in pediatric sepsis which are currently the subject of clinical trials.
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Affiliation(s)
- Katherine Elizabeth Bline
- Division of Critical Care Medicine, Department of Pediatrics, Nationwide Children’s Hospital, Columbus, OH 43205, USA;
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Viana F, Peringathara SS, Rizvi A, Schroeder GN. Host manipulation by bacterial type III and type IV secretion system effector proteases. Cell Microbiol 2021; 23:e13384. [PMID: 34392594 DOI: 10.1111/cmi.13384] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 07/28/2021] [Accepted: 07/30/2021] [Indexed: 01/08/2023]
Abstract
Proteases are powerful enzymes, which cleave peptide bonds, leading most of the time to irreversible fragmentation or degradation of their substrates. Therefore they control many critical cell fate decisions in eukaryotes. Bacterial pathogens exploit this power and deliver protease effectors through specialised secretion systems into host cells. Research over the past years revealed that the functions of protease effectors during infection are diverse, reflecting the lifestyles and adaptations to specific hosts; however, only a small number of peptidase families seem to have given rise to most of these protease virulence factors by the evolution of different substrate-binding specificities, intracellular activation and subcellular targeting mechanisms. Here, we review our current knowledge about the enzymology and function of protease effectors, which Gram-negative bacterial pathogens translocate via type III and IV secretion systems to irreversibly manipulate host processes. We highlight emerging concepts such as signalling by protease cleavage products and effector-triggered immunity, which host cells employ to detect and defend themselves against a protease attack. TAKE AWAY: Proteases irreversibly cleave proteins to control critical cell fate decisions. Gram-negative bacteria use type III and IV secretion systems to inject effectors. Protease effectors are integral weapons for the manipulation of host processes. Effectors evolved from few peptidase families to target diverse substrates. Effector-triggered immunity upon proteolytic attack emerges as host defence.
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Affiliation(s)
- Flávia Viana
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, Northern Ireland, UK
| | - Shruthi Sachidanandan Peringathara
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, Northern Ireland, UK
| | - Arshad Rizvi
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, Northern Ireland, UK
| | - Gunnar N Schroeder
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, Belfast, Northern Ireland, UK
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Abstract
OBJECTIVES Recent evidence from the fields of microbiology and immunology, as well as a small number of human sepsis studies, suggest that epigenetic regulation may play a central role in the pathogenesis of sepsis. The term "epigenetics" refers to regulatory mechanisms that control gene expression but are not related to changes in DNA sequence. These include DNA methylation, histone modifications, and regulation of transcription via non-coding RNAs. Epigenetic modifications, occurring in response to external stressors, lead to changes in gene expression, and thus lie at the intersection between genetics and the environment. In this review, we examine data from in vitro studies, animal studies, and the existing human sepsis studies in epigenetics to demonstrate that epigenetic mechanisms are likely central to the pathogenesis of sepsis and that epigenetic therapies may have potential in the treatment of sepsis and its associated organ failures. DATA SOURCES Online search of published scientific literature via Pubmed using the term "epigenetics" in combination with the terms "sepsis", "infection", "bacterial infection", "viral infection", "critical illness", "acute respiratory distress syndrome", and "acute lung injury". STUDY SELECTION Articles were chosen for inclusion based on their relevance to sepsis, acute inflammation, sepsis-related immune suppression, and sepsis-related organ failure. Reference lists were reviewed to identify additional relevant articles. DATA EXTRACTION Relevant data was extracted and synthesized for narrative review. DATA SYNTHESIS Epigenetic regulation is a key determinant of gene expression in sepsis. At the onset of infection, host-pathogen interactions often result in epigenetic alterations to host cells that favor pathogen survival. In parallel, the host inflammatory response is characterized by epigenetic modifications in key regulatory genes, including tumor necrosis factor and interleukin-1β. In human sepsis patients, multiple epigenetic modifying enzymes show differential expression in early sepsis, suggesting a role for epigenetics in coordinating the response to infection. In the later stages of sepsis, epigenetic modifications accompany endotoxin tolerance and the immune-suppressed state. In animal models, treatment with epigenetic modifiers can mitigate the effects of sepsis and improve survival as well as reverse sepsis-associated organ injury. CONCLUSIONS Epigenetic modifications are associated with key phases of sepsis, from the host-pathogen interaction, to acute inflammation, to immune suppression. Epigenetic markers show promise in the diagnosis and prognosis of sepsis and epigenetic modifying agents show promise as therapeutic tools in animal models of sepsis. Human studies in the area of epigenetics are sorely lacking and should be a priority for sepsis researchers.
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Hasan MK, El Qaidi S, Hardwidge PR. The T3SS Effector Protease NleC Is Active within Citrobacter rodentium. Pathogens 2021; 10:pathogens10050589. [PMID: 34065796 PMCID: PMC8151275 DOI: 10.3390/pathogens10050589] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 05/06/2021] [Accepted: 05/10/2021] [Indexed: 11/18/2022] Open
Abstract
Whether type III secretion system (T3SS) effector proteins encoded by Gram-negative bacterial pathogens have intra-bacterial activities is an important and emerging area of investigation. Gram-negative bacteria interact with their mammalian hosts by using secretion systems to inject virulence proteins directly into infected host cells. Many of these injected protein effectors are enzymes that modify the structure and inhibit the function of mammalian proteins. The underlying dogma is that T3SS effectors are inactive until they are injected into host cells, where they then fold into their active conformations. We previously observed that the T3SS effectors NleB and SseK1 glycosylate Citrobacter rodentium and Salmonella enterica proteins, respectively, leading to enhanced resistance to environmental stress. Here, we sought to extend these studies to determine whether the T3SS effector protease NleC is also active within C. rodentium. To do this, we expressed the best-characterized mammalian substrate of NleC, the NF-κB p65 subunit in C. rodentium and monitored its proteolytic cleavage as a function of NleC activity. Intra-bacterial p65 cleavage was strictly dependent upon NleC. A p65 mutant lacking the known CE cleavage motif was resistant to NleC. Thus, we conclude that, in addition to NleB, NleC is also enzymatically active within C. rodentium.
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Mooney BC, Mantz M, Graciet E, Huesgen PF. Cutting the line: manipulation of plant immunity by bacterial type III effector proteases. JOURNAL OF EXPERIMENTAL BOTANY 2021; 72:3395-3409. [PMID: 33640987 DOI: 10.1093/jxb/erab095] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2020] [Accepted: 02/25/2021] [Indexed: 06/12/2023]
Abstract
Pathogens and their hosts are engaged in an evolutionary arms race. Pathogen-derived effectors promote virulence by targeting components of a host's innate immune system, while hosts have evolved proteins that sense effectors and trigger a pathogen-specific immune response. Many bacterial effectors are translocated into host cells using type III secretion systems. Type III effector proteases irreversibly modify host proteins by cleavage of peptide bonds and are prevalent among both plant and animal bacterial pathogens. In plants, the study of model effector proteases has yielded important insights into the virulence mechanisms employed by pathogens to overcome their host's immune response, as well as into the mechanisms deployed by their hosts to detect these effector proteases and counteract their effects. In recent years, the study of a larger number of effector proteases, across a wider range of pathogens, has yielded novel insights into their functions and recognition. One key limitation that remains is the lack of methods to detect protease cleavage at the proteome-wide level. We review known substrates and mechanisms of plant pathogen type III effector proteases and compare their functions with those of known type III effector proteases of mammalian pathogens. Finally, we discuss approaches to uncover their function on a system-wide level.
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Affiliation(s)
- Brian C Mooney
- Department of Biology, Maynooth University, Maynooth, County Kildare, Ireland
| | - Melissa Mantz
- Central Institute for Engineering, Electronics and Analytics, ZEA-3, Forschungszentrum Jülich, Jülich, Germany
- CECAD, Medical Faculty and University Hospital, University of Cologne, Cologne, Germany
| | - Emmanuelle Graciet
- Department of Biology, Maynooth University, Maynooth, County Kildare, Ireland
- Kathleen Lonsdale Institute for Human Health Research, Maynooth University, Maynooth, Co. Kildare, Ireland
| | - Pitter F Huesgen
- Central Institute for Engineering, Electronics and Analytics, ZEA-3, Forschungszentrum Jülich, Jülich, Germany
- CECAD, Medical Faculty and University Hospital, University of Cologne, Cologne, Germany
- Institute for Biochemistry, Faculty of Mathematics and Natural Sciences, University of Cologne, Cologne, Germany
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9
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Takemura M, Haneda T, Idei H, Miki T, Okada N. A Salmonella type III effector, PipA, works in a different manner than the PipA family effectors GogA and GtgA. PLoS One 2021; 16:e0248975. [PMID: 33735297 PMCID: PMC7971870 DOI: 10.1371/journal.pone.0248975] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Accepted: 03/08/2021] [Indexed: 12/31/2022] Open
Abstract
Nuclear factor-kappa B (NF-κB) plays a critical role in the host defense against microbial pathogens. Many pathogens modulate NF-κB signaling to establish infection in their host. Salmonella enterica serovar Typhimurium (S. Typhimurium) possesses two type III secretion systems (T3SS-1 and T3SS-2) and directly injects many effector proteins into host cells. It has been reported that some effectors block NF-κB signaling, but the molecular mechanism of the inactivation of NF-κB signaling in S. Typhimurium is poorly understood. Here, we identified seven type III effectors-GogA, GtgA, PipA, SseK1, SseK2, SseK3, and SteE-that inhibited NF-κB activation in HeLa cells stimulated with TNF-α. We also determined that only GogA and GtgA are involved in regulation of the activation of NF-κB in HeLa cells infected with S. Typhimurium. GogA, GtgA, and PipA are highly homologous to one another and have the consensus zinc metalloprotease HEXXH motif. Our experiments demonstrated that GogA, GtgA, and PipA each directly cleaved NF-κB p65, whereas GogA and GtgA, but not PipA, inhibited the NF-κB activation in HeLa cells infected with S. Typhimurium. Further, expressions of the gogA or gtgA gene were induced under the SPI-1-and SPI-2-inducing conditions, but expression of the pipA gene was induced only under the SPI-2-inducing condition. We also showed that PipA was secreted into RAW264.7 cells through T3SS-2. Finally, we indicated that PipA elicits bacterial dissemination in the systemic stage of infection of S. Typhimurium via a T3SS-1-independent mechanism. Collectively, our results suggest that PipA, GogA and GtgA contribute to S. Typhimurium pathogenesis in different ways.
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Affiliation(s)
- Momo Takemura
- Laboratory of Microbiology, School of Pharmacy, Kitasato University, Minato, Tokyo, Japan
| | - Takeshi Haneda
- Laboratory of Microbiology, School of Pharmacy, Kitasato University, Minato, Tokyo, Japan
- * E-mail:
| | - Hikari Idei
- Laboratory of Microbiology, School of Pharmacy, Kitasato University, Minato, Tokyo, Japan
| | - Tsuyoshi Miki
- Laboratory of Microbiology, School of Pharmacy, Kitasato University, Minato, Tokyo, Japan
| | - Nobuhiko Okada
- Laboratory of Microbiology, School of Pharmacy, Kitasato University, Minato, Tokyo, Japan
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Mak H, Thurston TLM. Interesting Biochemistries in the Structure and Function of Bacterial Effectors. Front Cell Infect Microbiol 2021; 11:608860. [PMID: 33718265 PMCID: PMC7943720 DOI: 10.3389/fcimb.2021.608860] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2020] [Accepted: 01/13/2021] [Indexed: 11/13/2022] Open
Abstract
Bacterial effector proteins, delivered into host cells by specialized multiprotein secretion systems, are a key mediator of bacterial pathogenesis. Following delivery, they modulate a range of host cellular processes and functions. Strong selective pressures have resulted in bacterial effectors evolving unique structures that can mimic host protein biochemical activity or enable novel and distinct biochemistries. Despite the protein structure-function paradigm, effectors from different bacterial species that share biochemical activities, such as the conjugation of ubiquitin to a substrate, do not necessarily share structural or sequence homology to each other or the eukaryotic proteins that carry out the same function. Furthermore, some bacterial effectors have evolved structural variations to known protein folds which enable different or additional biochemical and physiological functions. Despite the overall low occurrence of intrinsically disordered proteins or regions in prokaryotic proteomes compared to eukaryotes proteomes, bacterial effectors appear to have adopted intrinsically disordered regions that mimic the disordered regions of eukaryotic signaling proteins. In this review, we explore examples of the diverse biochemical properties found in bacterial effectors that enable effector-mediated interference of eukaryotic signaling pathways and ultimately support pathogenesis. Despite challenges in the structural and functional characterisation of effectors, recent progress has been made in understanding the often unusual and fascinating ways in which these virulence factors promote pathogenesis. Nevertheless, continued work is essential to reveal the array of remarkable activities displayed by effectors.
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Affiliation(s)
| | - Teresa L. M. Thurston
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, United Kingdom
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11
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Hanford HE, Von Dwingelo J, Abu Kwaik Y. Bacterial nucleomodulins: A coevolutionary adaptation to the eukaryotic command center. PLoS Pathog 2021; 17:e1009184. [PMID: 33476322 PMCID: PMC7819608 DOI: 10.1371/journal.ppat.1009184] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Through long-term interactions with their hosts, bacterial pathogens have evolved unique arsenals of effector proteins that interact with specific host targets and reprogram the host cell into a permissive niche for pathogen proliferation. The targeting of effector proteins into the host cell nucleus for modulation of nuclear processes is an emerging theme among bacterial pathogens. These unique pathogen effector proteins have been termed in recent years as "nucleomodulins." The first nucleomodulins were discovered in the phytopathogens Agrobacterium and Xanthomonas, where their nucleomodulins functioned as eukaryotic transcription factors or integrated themselves into host cell DNA to promote tumor induction, respectively. Numerous nucleomodulins were recently identified in mammalian pathogens. Bacterial nucleomodulins are an emerging family of pathogen effector proteins that evolved to target specific components of the host cell command center through various mechanisms. These mechanisms include: chromatin dynamics, histone modification, DNA methylation, RNA splicing, DNA replication, cell cycle, and cell signaling pathways. Nucleomodulins may induce short- or long-term epigenetic modifications of the host cell. In this extensive review, we discuss the current knowledge of nucleomodulins from plant and mammalian pathogens. While many nucleomodulins are already identified, continued research is instrumental in understanding their mechanisms of action and the role they play during the progression of pathogenesis. The continued study of nucleomodulins will enhance our knowledge of their effects on nuclear chromatin dynamics, protein homeostasis, transcriptional landscapes, and the overall host cell epigenome.
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Affiliation(s)
- Hannah E. Hanford
- Department of Microbiology and Immunology, University of Louisville, Kentucky, United States of America
| | - Juanita Von Dwingelo
- Department of Microbiology and Immunology, University of Louisville, Kentucky, United States of America
| | - Yousef Abu Kwaik
- Department of Microbiology and Immunology, University of Louisville, Kentucky, United States of America
- Center for Predicative Medicine, College of Medicine, University of Louisville, Kentucky, United States of America
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12
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Vibrio cholerae Type VI Activity Alters Motility Behavior in Mucin. J Bacteriol 2020; 202:JB.00261-20. [PMID: 32868403 DOI: 10.1128/jb.00261-20] [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: 04/30/2020] [Accepted: 08/11/2020] [Indexed: 01/16/2023] Open
Abstract
Motility is required for many bacterial pathogens to reach and colonize target sites. Vibrio cholerae traverses a thick mucus barrier coating the small intestine to reach the underlying epithelium. We screened a transposon library in motility medium containing mucin to identify factors that influence mucus transit. Lesions in structural genes of the type VI secretion system (T6SS) were among those recovered. Two-dimensional (2D) and 3D single-cell tracking was used to compare the motility behaviors of wild-type cells and a mutant that collectively lacked three essential T6SS structural genes (T6SS-). In the absence of mucin, wild-type and T6SS- cells exhibited similar speeds and run-reverse-flick (RRF) swimming patterns, in which forward-moving cells briefly backtrack before stochastically reorienting (flicking) in a new direction upon resuming forward movement. We show that mucin induced T6SS expression and activity in wild-type bacteria but significantly decreased their swimming speed and flicking, yielding curvilinear or near-surface circular traces for many cells. Conversely, mucin slowed T6SS- cells to a lesser extent, and many continued to flick and produce RRF-like traces. ΔcheY3 cells, which exclusively swim in the forward direction and thus cannot flick, also produced curvilinear traces with or without mucin present and, on occasion, near-surface circular traces in the presence of mucin. The dependence of flicking on swimming speed suggested that mucin-induced T6SS activity further decreased V. cholerae motility and thereby reduced flicking probability during reverse-to-forward transitions. We propose that this encourages cells to continue on their current trajectory rather than reorienting, which may benefit those tracking toward the epithelial surface.IMPORTANCE V. cholerae deploys an arsenal of virulence factors as it attempts to traverse a protective mucus layer and reach the epithelial surface of the distal small intestine. The T6SS used to cull bacterial competition during infection is induced by mucus. We show that this activity may serve an additional purpose by further decreasing motility in the presence of mucin, thereby reducing the probability of speed-dependent, near-perpendicular directional changes. We posit that this encourages cells to maintain course rather than change direction, which may aid those attempting to reach and colonize the epithelial surface.
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13
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Meyer MD, Ryck JD, Goormachtig S, Van Damme P. Keeping in Touch with Type-III Secretion System Effectors: Mass Spectrometry-Based Proteomics to Study Effector-Host Protein-Protein Interactions. Int J Mol Sci 2020; 21:E6891. [PMID: 32961832 PMCID: PMC7555288 DOI: 10.3390/ijms21186891] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2020] [Revised: 09/15/2020] [Accepted: 09/16/2020] [Indexed: 01/03/2023] Open
Abstract
Manipulation of host cellular processes by translocated bacterial effectors is key to the success of bacterial pathogens and some symbionts. Therefore, a comprehensive understanding of effectors is of critical importance to understand infection biology. It has become increasingly clear that the identification of host protein targets contributes invaluable knowledge to the characterization of effector function during pathogenesis. Recent advances in mapping protein-protein interaction networks by means of mass spectrometry-based interactomics have enabled the identification of host targets at large-scale. In this review, we highlight mass spectrometry-driven proteomics strategies and recent advances to elucidate type-III secretion system effector-host protein-protein interactions. Furthermore, we highlight approaches for defining spatial and temporal effector-host interactions, and discuss possible avenues for studying natively delivered effectors in the context of infection. Overall, the knowledge gained when unravelling effector complexation with host factors will provide novel opportunities to control infectious disease outcomes.
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Affiliation(s)
- Margaux De Meyer
- Department of Biochemistry and Microbiology, Ghent University, K. L. Ledeganckstraat 35, 9000 Ghent, Belgium; (M.D.M.); (J.D.R.)
- VIB Center for Medical Biotechnology, Technologiepark 75, 9052 Zwijnaarde, Belgium
| | - Joren De Ryck
- Department of Biochemistry and Microbiology, Ghent University, K. L. Ledeganckstraat 35, 9000 Ghent, Belgium; (M.D.M.); (J.D.R.)
- VIB Center for Plant Systems Biology, Technologiepark 71, 9052 Zwijnaarde, Belgium;
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Technologiepark 71, 9052 Zwijnaarde, Belgium
| | - Sofie Goormachtig
- VIB Center for Plant Systems Biology, Technologiepark 71, 9052 Zwijnaarde, Belgium;
- Department of Plant Biotechnology and Bioinformatics, Ghent University, Technologiepark 71, 9052 Zwijnaarde, Belgium
| | - Petra Van Damme
- Department of Biochemistry and Microbiology, Ghent University, K. L. Ledeganckstraat 35, 9000 Ghent, Belgium; (M.D.M.); (J.D.R.)
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Riebisch AK, Mühlen S. Attaching and effacing pathogens: the effector ABC of immune subversion. Future Microbiol 2020; 15:945-958. [PMID: 32716209 DOI: 10.2217/fmb-2019-0274] [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] [Indexed: 11/21/2022] Open
Abstract
The innate immune response resembles an essential barrier to bacterial infection. Many bacterial pathogens have, therefore, evolved mechanisms to evade from or subvert the host immune response in order to colonize, survive and multiply. The attaching and effacing pathogens enteropathogenic Escherichia coli, enterohaemorrhagic E. coli, Escherichia albertii and Citrobacter rodentium are Gram-negative extracellular gastrointestinal pathogens. They use a type III secretion system to inject effector proteins into the host cell to manipulate a variety of cellular processes. Over the last decade, considerable progress was made in identifying and characterizing the effector proteins of attaching and effacing pathogens that are involved in the inhibition of innate immune signaling pathways, in determining their host cell targets and elucidating the mechanisms they employ. Their functions will be reviewed here.
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Affiliation(s)
- Anna Katharina Riebisch
- Systems-Oriented Immunology & Inflammation Research, Helmholtz Centre for Infection Research, 38124 Braunschweig, Germany.,Institute for Molecular & Clinical Immunology, Otto von Guericke University Magdeburg, 39106 Magdeburg, Germany.,Department of Molecular Immunology, Ruhr-University Bochum, 44801 Bochum, Germany
| | - Sabrina Mühlen
- Institute for Infectiology, University of Münster, 48149 Münster, Germany.,German Center for Infection Research (DZIF), Associated Site University of Münster, 48149 Münster, Germany
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15
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Denzer L, Schroten H, Schwerk C. From Gene to Protein-How Bacterial Virulence Factors Manipulate Host Gene Expression During Infection. Int J Mol Sci 2020; 21:ijms21103730. [PMID: 32466312 PMCID: PMC7279228 DOI: 10.3390/ijms21103730] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Revised: 05/19/2020] [Accepted: 05/20/2020] [Indexed: 02/06/2023] Open
Abstract
Bacteria evolved many strategies to survive and persist within host cells. Secretion of bacterial effectors enables bacteria not only to enter the host cell but also to manipulate host gene expression to circumvent clearance by the host immune response. Some effectors were also shown to evade the nucleus to manipulate epigenetic processes as well as transcription and mRNA procession and are therefore classified as nucleomodulins. Others were shown to interfere downstream with gene expression at the level of mRNA stability, favoring either mRNA stabilization or mRNA degradation, translation or protein stability, including mechanisms of protein activation and degradation. Finally, manipulation of innate immune signaling and nutrient supply creates a replicative niche that enables bacterial intracellular persistence and survival. In this review, we want to highlight the divergent strategies applied by intracellular bacteria to evade host immune responses through subversion of host gene expression via bacterial effectors. Since these virulence proteins mimic host cell enzymes or own novel enzymatic functions, characterizing their properties could help to understand the complex interactions between host and pathogen during infections. Additionally, these insights could propose potential targets for medical therapy.
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16
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Pan X, Luo J, Li S. Bacteria-Catalyzed Arginine Glycosylation in Pathogens and Host. Front Cell Infect Microbiol 2020; 10:185. [PMID: 32411621 PMCID: PMC7199390 DOI: 10.3389/fcimb.2020.00185] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Accepted: 04/07/2020] [Indexed: 01/25/2023] Open
Abstract
In recent years, protein glycosylation in pathogenic bacteria has attracted more and more attention, and accumulating evidence indicated that this type of posttranslational modification is involved in many physiological processes. The NleB from several enteropathogenic bacteria species as well as SseK from Salmonella enterica are type III secretion system effectors, which have an atypical N-acetylglucosamine (N-GlcNAc) transferase activity that specifically modified a conserved arginine in TRADD, FADD, and RIPK1. NleB/SseKs GlcNAcylation of death domain proteins abrogates homotypic and heterotypic death receptors/adaptors interactions, thereby blocking an important antimicrobial host response. Interestingly, NleB/SseKs could also GlcNAcylate themselves, and self-GlcNAcylation of NleB, SseK1, and SseK3 are crucial for their biological activity during infection. In addition, EarP (EF-P specific arginine rhamnosyl transferase for Posttranslational activation) catalyzes arginine rhamnosylation of translation elongation factor P (EF-P). Importantly, this kind of N-linked protein glycosylation is not only important for EF-P dependent rescue of polyproline stalled ribosomes but also for pathogenicity in Pseudomonas aeruginosa and other clinically relevant bacteria. Glycosylation of arginine is unique because the guanidine group of arginine has a high acid dissociation constant value and representing an extremely poor nucleophile. Recently, the crystal structures of NleB, SseKs, EarP, arginine GlcNAcylated death domain-containing proteins, NleB/FADD-DD, and EarP/EF-P/dTDP-β-L-rhamnose were solved by our group and other groups, revealing the unique catalytic mechanisms. In this review, we provide detailed information about the currently known arginine glycosyltransferases and their potential catalytic mechanisms.
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Affiliation(s)
- Xing Pan
- Institute of Infection and Immunity, Taihe Hospital, Hubei University of Medicine, Shiyan, China.,College of Biomedicine and Health, Huazhong Agricultural University, Wuhan, China.,College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
| | - Jie Luo
- Institute of Infection and Immunity, Taihe Hospital, Hubei University of Medicine, Shiyan, China
| | - Shan Li
- Institute of Infection and Immunity, Taihe Hospital, Hubei University of Medicine, Shiyan, China.,College of Biomedicine and Health, Huazhong Agricultural University, Wuhan, China.,College of Life Science and Technology, Huazhong Agricultural University, Wuhan, China
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17
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Bacterial Factors Targeting the Nucleus: The Growing Family of Nucleomodulins. Toxins (Basel) 2020; 12:toxins12040220. [PMID: 32244550 PMCID: PMC7232420 DOI: 10.3390/toxins12040220] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2020] [Revised: 03/23/2020] [Accepted: 03/29/2020] [Indexed: 12/18/2022] Open
Abstract
Pathogenic bacteria secrete a variety of proteins that manipulate host cell function by targeting components of the plasma membrane, cytosol, or organelles. In the last decade, several studies identified bacterial factors acting within the nucleus on gene expression or other nuclear processes, which has led to the emergence of a new family of effectors called “nucleomodulins”. In human and animal pathogens, Listeria monocytogenes for Gram-positive bacteria and Anaplasma phagocytophilum, Ehrlichia chaffeensis, Chlamydia trachomatis, Legionella pneumophila, Shigella flexneri, and Escherichia coli for Gram-negative bacteria, have led to pioneering discoveries. In this review, we present these paradigms and detail various mechanisms and core elements (e.g., DNA, histones, epigenetic regulators, transcription or splicing factors, signaling proteins) targeted by nucleomodulins. We particularly focus on nucleomodulins interacting with epifactors, such as LntA of Listeria and ankyrin repeat- or tandem repeat-containing effectors of Rickettsiales, and nucleomodulins from various bacterial species acting as post-translational modification enzymes. The study of bacterial nucleomodulins not only generates important knowledge about the control of host responses by microbes but also creates new tools to decipher the dynamic regulations that occur in the nucleus. This research also has potential applications in the field of biotechnology. Finally, this raises questions about the epigenetic effects of infectious diseases.
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18
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MicroRNAs regulate innate immunity against uropathogenic and commensal-like Escherichia coli infections in the surrogate insect model Galleria mellonella. Sci Rep 2020; 10:2570. [PMID: 32054914 PMCID: PMC7018962 DOI: 10.1038/s41598-020-59407-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2019] [Accepted: 01/15/2020] [Indexed: 12/23/2022] Open
Abstract
Uropathogenic Escherichia coli (UPEC) strains cause symptomatic urinary tract infections in humans whereas commensal-like E. coli strains in the urinary bladder cause long-term asymptomatic bacteriuria (ABU). We previously reported that UPEC and ABU strains differentially regulate key DNA methylation and histone acetylation components in the surrogate insect host Galleria mellonella to epigenetically modulate innate immunity-related gene expression, which in turn controls bacterial growth. In this follow-up study, we infected G. mellonella larvae with UPEC strain CFT073 or ABU strain 83972 to identify differences in the expression of microRNAs (miRNAs), a class of non-coding RNAs that regulate gene expression at the post-transcriptional level. Our small RNA sequencing analysis showed that UPEC and ABU infections caused significant changes in the abundance of miRNAs in the larvae, and highlighted the differential expression of 147 conserved miRNAs and 95 novel miRNA candidates. We annotated the G. mellonella genome sequence to investigate the miRNA-regulated expression of genes encoding antimicrobial peptides, signaling proteins, and enzymatic regulators of DNA methylation and histone acetylation in infected larvae. Our results indicate that miRNAs play a role in the epigenetic reprograming of innate immunity in G. mellonella larvae to distinguish between pathogenic and commensal strains of E. coli.
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19
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Pu M, Storms E, Chodur DM, Rowe-Magnus DA. Calcium-dependent site-switching regulates expression of the atypical iam pilus locus in Vibrio vulnificus. Environ Microbiol 2019; 22:4167-4182. [PMID: 31355512 DOI: 10.1111/1462-2920.14763] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2019] [Accepted: 07/25/2019] [Indexed: 12/21/2022]
Abstract
The opportunistic human pathogen Vibrio vulnificus inhabits warm coastal waters and asymptomatically colonizes seafood, most commonly oysters. We previously characterized an isolate that exhibited greater biofilm formation, aggregation and oyster colonization than its parent. This was due, in part, to the production of a Type IV Tad pilus (Iam). However, the locus lacked key processing and regulatory genes required for pilus production. Here, we identify a pilin peptidase iamP, and LysR-type regulator (LRTR) iamR, that fulfil these roles and show that environmental calcium, which oysters enrich for shell repair and growth, regulates iam expression. The architecture of the iam locus differs from the classical LRTR paradigm and requires an additional promoter to be integrated into the regulatory network. IamR specifically recognized the iamR promoter (PiamR ) and the intergenic iamP-iamA region (PiamP-A ). PiamR exhibited classical negative auto-regulation but, strikingly, IamR inversely regulated the divergent iamP and iamA promoters in a calcium-dependent manner. Moreover, expression of the c-di-GMP and calcium-regulated, biofilm-promoting brp exopolysaccharide was IamA-dependent. These results support a scenario in which the calcium-enriched oyster environment triggers IamP-mediated processing of prepilin amassed in the periplasm for rapid pilin elaboration and subsequent BRP production to promote colonization.
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Affiliation(s)
- Meng Pu
- Department of Biology, Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN, USA
| | - Emily Storms
- Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN, USA
| | - Dan M Chodur
- Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN, USA
| | - Dean A Rowe-Magnus
- Department of Biology, Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN, USA.,Molecular and Cellular Biochemistry, Indiana University, Bloomington, IN, USA
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20
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Chen XP, Zheng H, Li WG, Chen GD, Lu JX. Bacteria-induced susceptibility to Candida albicans super-infection in mice via monocyte methyltransferase Setdb2. Cell Microbiol 2018; 20:e12860. [PMID: 29749709 DOI: 10.1111/cmi.12860] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Revised: 04/02/2018] [Accepted: 05/01/2018] [Indexed: 12/22/2022]
Abstract
Systemic bacterial infections are prone to secondary Candida albicans super-infection. However, the molecular mechanisms involved remain poorly understood. In this study, a model comprising sublethal cecal ligation and puncture plus C. albicans intravenous injection was applied to mimic the situation in super-infection. Compared with mice without systemic bacterial infection, mice with systemic bacterial infection had lower antifungal gene expression (including Il1b, Tnf, Il6, Ifnb, Ifng, Cxcl1, and Ccr2) in monocytes and less inflammatory monocytes and neutrophils infiltrating into the kidney when challenged with C. albicans. Further, lentivirus-mediated Setdb2-knockout and overexpression experiments verified that Setdb2 levels in monocytes correlated negatively with antifungal gene expression and survival rates. Transcriptional repression was probably achieved by Setdb2 through H3 methylation at lysine 9 in promoter regions of these antifungal genes.
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Affiliation(s)
- Xiao-Ping Chen
- State Key Laboratory for Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Department of Nosocomial Infection, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Hao Zheng
- State Key Laboratory for Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Department of Nosocomial Infection, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Wen-Ge Li
- State Key Laboratory for Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Department of Nosocomial Infection, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
| | - Guo-Dong Chen
- Department of Gastroenterology, Peking University People's Hospital, Beijing, China
| | - Jin-Xing Lu
- State Key Laboratory for Infectious Disease Prevention and Control, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, Department of Nosocomial Infection, National Institute for Communicable Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing, China
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21
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Shenoy AR, Furniss RCD, Goddard PJ, Clements A. Modulation of Host Cell Processes by T3SS Effectors. Curr Top Microbiol Immunol 2018; 416:73-115. [PMID: 30178263 DOI: 10.1007/82_2018_106] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Two of the enteric Escherichia coli pathotypes-enteropathogenic E. coli (EPEC) and enterohaemorrhagic E. coli (EHEC)-have a conserved type 3 secretion system which is essential for virulence. The T3SS is used to translocate between 25 and 50 bacterial proteins directly into the host cytosol where they manipulate a variety of host cell processes to establish a successful infection. In this chapter, we discuss effectors from EPEC/EHEC in the context of the host proteins and processes that they target-the actin cytoskeleton, small guanosine triphosphatases and innate immune signalling pathways that regulate inflammation and cell death. Many of these translocated proteins have been extensively characterised, which has helped obtain insights into the mechanisms of pathogenesis of these bacteria and also understand the host pathways they target in more detail. With increasing knowledge of the positive and negative regulation of host signalling pathways by different effectors, a future challenge is to investigate how the specific effector repertoire of each strain cooperates over the course of an infection.
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Affiliation(s)
- Avinash R Shenoy
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, Armstrong Road, SW7 2AZ, London, UK
| | - R Christopher D Furniss
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, Armstrong Road, SW7 2AZ, London, UK
| | - Philippa J Goddard
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, Armstrong Road, SW7 2AZ, London, UK
| | - Abigail Clements
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, Armstrong Road, SW7 2AZ, London, UK.
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22
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Grabiec AM, Potempa J. Epigenetic regulation in bacterial infections: targeting histone deacetylases. Crit Rev Microbiol 2017; 44:336-350. [PMID: 28971711 DOI: 10.1080/1040841x.2017.1373063] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Pathogens have developed sophisticated strategies to evade the immune response, among which manipulation of host cellular epigenetic mechanisms plays a prominent role. In the last decade, modulation of histone acetylation in host cells has emerged as an efficient strategy of bacterial immune evasion. Virulence factors and metabolic products of pathogenic microorganisms alter expression and activity of histone acetyltransferases (HATs) and histone deacetylases (HDACs) to suppress transcription of host defense genes through epigenetic changes in histone acetylation marks. This new avenue of pathogen-host interactions is particularly important in light of introduction of HDAC inhibitors into clinical practice. Considerable effort is currently being applied to better understand the effects of HDAC inhibitors on the quality of immune responses to pathogens and to characterize the therapeutic potential of these compounds in microbial infections. In this review, we will discuss the recently discovered mechanisms utilized by bacteria to facilitate their survival within infected hosts through subversion of the host acetylation system and the effects of acetylation modulators, including HDAC inhibitors and bromodomain-containing BET protein inhibitors, on innate immune responses against microbial pathogens. Integration of these two lines of experimental evidence provides critical information on the perspectives of epigenetic therapies targeting protein acetylation in infectious diseases.
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Affiliation(s)
- Aleksander M Grabiec
- a Department of Microbiology , Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University , Kraków , Poland
| | - Jan Potempa
- a Department of Microbiology , Faculty of Biochemistry, Biophysics and Biotechnology, Jagiellonian University , Kraków , Poland.,b Department of Oral Immunology and Infectious Diseases , University of Louisville School of Dentistry , Louisville , KY , USA
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23
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24
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Zhuang X, Chen Z, He C, Wang L, Zhou R, Yan D, Ge B. Modulation of host signaling in the inflammatory response by enteropathogenic Escherichia coli virulence proteins. Cell Mol Immunol 2017; 14:237-244. [PMID: 27796284 PMCID: PMC5360883 DOI: 10.1038/cmi.2016.52] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Revised: 07/24/2016] [Accepted: 07/25/2016] [Indexed: 12/27/2022] Open
Abstract
To successfully infect host cells and evade the host immune response, a type III secretion system (T3SS) is commonly used by enteric bacterial pathogens such as enteropathogenic Escherichia coli (EPEC). Recent findings have revealed that various effectors are injected into host cells through the T3SS and exert an inhibitory effect on inflammatory signaling pathways, subverting the immune responses to these pathogens. Here we review recent studies aimed at addressing the modulation of several important inflammatory signaling pathways modulated by EPEC effector proteins, such as the nuclear factor-κB (NF-κB) and mitogen-activated protein kinase (MAPK) pathways, which provides insight into the unfinished work in this unexplored field and helps to identify novel positions in inflammatory signaling networks for EPEC effectors.Cellular & Molecular Immunology advance online publication, 31 October 2016; doi:10.1038/cmi.2016.52.
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Affiliation(s)
- Xiaonan Zhuang
- Department of Immunology and Key Laboratory of Medical Molecular Virology of MOE/MOH, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China
| | - Zijuan Chen
- Department of Immunology and Key Laboratory of Medical Molecular Virology of MOE/MOH, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China
| | - Chenxi He
- Department of Microbiology and Immunology, Tongji University School of Medicine, Shanghai 200092, China
| | - Lin Wang
- Department of Microbiology and Immunology, Tongji University School of Medicine, Shanghai 200092, China
| | - Ruixue Zhou
- Department of Immunology and Key Laboratory of Medical Molecular Virology of MOE/MOH, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China
| | - Dapeng Yan
- Department of Immunology and Key Laboratory of Medical Molecular Virology of MOE/MOH, School of Basic Medical Sciences, Fudan University, Shanghai 200032, China
| | - Baoxue Ge
- Department of Microbiology and Immunology, Tongji University School of Medicine, Shanghai 200092, China
- Shanghai Key Laboratory of Tuberculosis, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai 200092, China
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25
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Scanlan E, Yu L, Maskell D, Choudhary J, Grant A. A quantitative proteomic screen of the Campylobacter jejuni flagellar-dependent secretome. J Proteomics 2017; 152:181-187. [PMID: 27865792 PMCID: PMC5223770 DOI: 10.1016/j.jprot.2016.11.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Revised: 11/11/2016] [Accepted: 11/14/2016] [Indexed: 11/24/2022]
Abstract
Campylobacter jejuni is the leading cause of bacterial gastroenteritis in the world. A number of factors are believed to contribute to the ability of C. jejuni to cause disease within the human host including the secretion of non-flagellar proteins via the flagellar type III secretion system (FT3SS). Here for the first time we have utilised quantitative proteomics using stable isotope labelling by amino acids in cell culture (SILAC), and label-free liquid chromatography-mass spectrometry (LC/MS), to compare supernatant samples from C. jejuni M1 wild type and flagella-deficient (flgG mutant) strains to identify putative novel proteins secreted via the FT3SS. Genes encoding proteins that were candidates for flagellar secretion, derived from the LC/MS and SILAC datasets, were deleted. Infection of human CACO-2 tissue culture cells using these mutants resulted in the identification of novel genes required for interactions with these cells. This work has shown for the first time that both CJM1_0791 and CJM1_0395 are dependent on the flagellum for their presence in supernatants from C. jejuni stains M1 and 81-176. BIOLOGICAL SIGNIFICANCE This study provides the most complete description of the Campylobac er jejuni secretome to date. SILAC and label-free proteomics comparing mutants with or without flagella have resulted in the identification of two C. jejuni proteins that are dependent on flagella for their export from the bacterial cell.
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Affiliation(s)
- Eoin Scanlan
- Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, United Kingdom
| | - Lu Yu
- Proteomic Mass Spectrometry, Wellcome Trust Sanger Institute, Hinxton CB10 1SA, United Kingdom
| | - Duncan Maskell
- Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, United Kingdom
| | - Jyoti Choudhary
- Proteomic Mass Spectrometry, Wellcome Trust Sanger Institute, Hinxton CB10 1SA, United Kingdom
| | - Andrew Grant
- Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, United Kingdom.
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26
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Pearson JS, Giogha C, Wong Fok Lung T, Hartland EL. The Genetics of EnteropathogenicEscherichia coliVirulence. Annu Rev Genet 2016; 50:493-513. [DOI: 10.1146/annurev-genet-120215-035138] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Jaclyn S. Pearson
- Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria 3010, Australia; , , ,
| | - Cristina Giogha
- Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria 3010, Australia; , , ,
| | - Tania Wong Fok Lung
- Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria 3010, Australia; , , ,
| | - Elizabeth L. Hartland
- Department of Microbiology and Immunology, The Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria 3010, Australia; , , ,
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27
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Rolando M, Gomez-Valero L, Buchrieser C. Bacterial remodelling of the host epigenome: functional role and evolution of effectors methylating host histones. Cell Microbiol 2016; 17:1098-107. [PMID: 26031999 DOI: 10.1111/cmi.12463] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Revised: 05/15/2015] [Accepted: 05/25/2015] [Indexed: 12/25/2022]
Abstract
The modulation of the chromatin organization of eukaryotic cells plays an important role in regulating key cellular processes including host defence mechanisms against pathogens. Thus, to successfully survive in a host cell, a sophisticated bacterial strategy is the subversion of nuclear processes of the eukaryotic cell. Indeed, the number of bacterial proteins that target host chromatin to remodel the host epigenetic machinery is expanding. Some of the identified bacterial effectors that target the chromatin machinery are 'eukaryotic-like' proteins as they mimic eukaryotic histone writers in carrying the same enzymatic activities. The best-studied examples are the SET domain proteins that methylate histones to change the chromatin landscape. In this review, we will discuss SET domain proteins identified in the Legionella, Chlamydia and Bacillus genomes that encode enzymatic activities targeting host histones. Moreover, we discuss their possible origin as having evolved from prokaryotic ancestors or having been acquired from their eukaryotic hosts during their co-evolution. The characterization of such bacterial effectors as modifiers of the host chromatin landscape is an exciting field of research as it elucidates new bacterial strategies to not only manipulate host functions through histone modifications but it may also identify new modifications of the mammalian host cells not known before.
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Affiliation(s)
- Monica Rolando
- Institut Pasteur, Biologie des Bactéries Intracellulaires, Paris, France.,CNRS UMR 3525, Paris, France
| | - Laura Gomez-Valero
- Institut Pasteur, Biologie des Bactéries Intracellulaires, Paris, France.,CNRS UMR 3525, Paris, France
| | - Carmen Buchrieser
- Institut Pasteur, Biologie des Bactéries Intracellulaires, Paris, France.,CNRS UMR 3525, Paris, France
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28
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Law RJ, Law HT, Scurll JM, Scholz R, Santos AS, Shames SR, Deng W, Croxen MA, Li Y, de Hoog CL, van der Heijden J, Foster LJ, Guttman JA, Finlay BB. Quantitative Mass Spectrometry Identifies Novel Host Binding Partners for Pathogenic Escherichia coli Type III Secretion System Effectors. J Proteome Res 2016; 15:1613-22. [DOI: 10.1021/acs.jproteome.6b00074] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | - Hong T. Law
- Department
of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada V5A 1S6
| | | | | | | | | | | | | | | | | | | | | | - Julian A. Guttman
- Department
of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada V5A 1S6
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29
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Hodgson A, Wan F. Interference with nuclear factor kappaB signaling pathway by pathogen-encoded proteases: global and selective inhibition. Mol Microbiol 2016; 99:439-52. [PMID: 26449378 PMCID: PMC5003429 DOI: 10.1111/mmi.13245] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/08/2015] [Indexed: 01/26/2023]
Abstract
Pathogens have evolved a myriad of ways to abrogate and manipulate the host response to infections. Of the various mechanisms involved, pathogen-encoded and sometimes host-encoded proteases are an important category of virulence factors that cause robust changes on the host response by targeting key proteins along signaling cascades. The nuclear factor kappaB (NF-κB) signaling pathway is a crucial regulatory mechanism for the cell, controlling the expression of survival, immune and proliferation genes. Proteases from pathogens of almost all types have been demonstrated to target and cleave members of the NF-κB signaling pathway at nearly every level. This review provides discussion of proteases targeting the most abundant NF-κB subunit, p65, and the impact of protease-mediated p65 cleavage on the immune responses and survival of the infected host cell. After examining various examples of protease interference, it becomes evident that the cleavage fragments produced by pathogen-driven proteolytic processing should be further characterized to determine whether they have novel and unique functions within the cell. The selective targeting of p65 and its effect on gene transcription reveals unique mechanisms by which pathogens acutely alter their microenvironment, and further research may open new opportunities for novel therapeutics to combat pathogens.
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Affiliation(s)
- Andrea Hodgson
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21025, USA
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21025, USA
| | - Fengyi Wan
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21025, USA
- Department of Oncology, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University, Baltimore, MD 21287, USA
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30
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Targeting of host organelles by pathogenic bacteria: a sophisticated subversion strategy. Nat Rev Microbiol 2015; 14:5-19. [PMID: 26594043 DOI: 10.1038/nrmicro.2015.1] [Citation(s) in RCA: 108] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Many bacterial pathogens have evolved the ability to subvert and exploit host functions in order to enter and replicate in eukaryotic cells. For example, bacteria have developed specific mechanisms to target eukaryotic organelles such as the nucleus, the mitochondria, the endoplasmic reticulum and the Golgi apparatus. In this Review, we highlight the most recent advances in our understanding of the mechanisms that bacterial pathogens use to target these organelles. We also discuss how these strategies allow bacteria to manipulate host functions and to ultimately enable bacterial infection.
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Scholz R, Imami K, Scott NE, Trimble WS, Foster LJ, Finlay BB. Novel Host Proteins and Signaling Pathways in Enteropathogenic E. coli Pathogenesis Identified by Global Phosphoproteome Analysis. Mol Cell Proteomics 2015; 14:1927-45. [PMID: 25944883 DOI: 10.1074/mcp.m114.046847] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2014] [Indexed: 12/21/2022] Open
Abstract
Enteropathogenic Escherichia coli (EPEC) uses a type III secretion system (T3SS) to directly translocate effector proteins into host cells where they play a pivotal role in subverting host cell signaling needed for disease. However, our knowledge of how EPEC affects host protein phosphorylation is limited to a few individual protein studies. We employed a quantitative proteomics approach to globally map alterations in the host phosphoproteome during EPEC infection. By characterizing host phosphorylation events at various time points throughout infection, we examined how EPEC dynamically impacts the host phosphoproteome over time. This experimental setup also enabled identification of T3SS-dependent and -independent changes in host phosphorylation. Specifically, T3SS-regulated events affected various cellular processes that are known EPEC targets, including cytoskeletal organization, immune signaling, and intracellular trafficking. However, the involvement of phosphorylation in these events has thus far been poorly studied. We confirmed the MAPK family as an established key host player, showed its central role in signal transduction during EPEC infection, and extended the repertoire of known signaling hubs with previously unrecognized proteins, including TPD52, CIN85, EPHA2, and HSP27. We identified altered phosphorylation of known EPEC targets, such as cofilin, where the involvement of phosphorylation has so far been undefined, thus providing novel mechanistic insights into the roles of these proteins in EPEC infection. An overlap of regulated proteins, especially those that are cytoskeleton-associated, was observed when compared with the phosphoproteome of Shigella-infected cells. We determined the biological relevance of the phosphorylation of a novel protein in EPEC pathogenesis, septin-9 (SEPT9). Both siRNA knockdown and a phosphorylation-impaired SEPT9 mutant decreased bacterial adherence and EPEC-mediated cell death. In contrast, a phosphorylation-mimicking SEPT9 mutant rescued these effects. Collectively, this study provides the first global analysis of phosphorylation-mediated processes during infection with an extracellular, diarrheagenic bacterial pathogen.
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Affiliation(s)
| | - Koshi Imami
- §Centre for High-Throughput Biology, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - Nichollas E Scott
- §Centre for High-Throughput Biology, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
| | - William S Trimble
- ¶Cell Biology Program, Hospital for Sick Children and ‖Department of Biochemistry, University of Toronto, Toronto, Ontario M5G 1X8, Canada
| | - Leonard J Foster
- §Centre for High-Throughput Biology, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada, **Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada, and
| | - B Brett Finlay
- From the ‡Michael Smith Laboratories and **Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada, and ¶¶Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada
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Hodgson A, Wier EM, Fu K, Sun X, Yu H, Zheng W, Sham HP, Johnson K, Bailey S, Vallance BA, Wan F. Metalloprotease NleC suppresses host NF-κB/inflammatory responses by cleaving p65 and interfering with the p65/RPS3 interaction. PLoS Pathog 2015; 11:e1004705. [PMID: 25756944 PMCID: PMC4355070 DOI: 10.1371/journal.ppat.1004705] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Accepted: 01/26/2015] [Indexed: 11/18/2022] Open
Abstract
Attaching/Effacing (A/E) pathogens including enteropathogenic Escherichia coli (EPEC), enterohemorrhagic E. coli (EHEC) and the rodent equivalent Citrobacter rodentium are important causative agents of foodborne diseases. Upon infection, a myriad of virulence proteins (effectors) encoded by A/E pathogens are injected through their conserved type III secretion systems (T3SS) into host cells where they interfere with cell signaling cascades, in particular the nuclear factor kappaB (NF-κB) signaling pathway that orchestrates both innate and adaptive immune responses for host defense. Among the T3SS-secreted non-LEE-encoded (Nle) effectors, NleC, a metalloprotease, has been recently elucidated to modulate host NF-κB signaling by cleaving NF-κB Rel subunits. However, it remains elusive how NleC recognizes NF-κB Rel subunits and how the NleC-mediated cleavage impacts on host immune responses in infected cells and animals. In this study, we show that NleC specifically targets p65/RelA through an interaction with a unique N-terminal sequence in p65. NleC cleaves p65 in intestinal epithelial cells, albeit a small percentage of the molecule, to generate the p65¹⁻³⁸ fragment during C. rodentium infection in cultured cells. Moreover, the NleC-mediated p65 cleavage substantially affects the expression of a subset of NF-κB target genes encoding proinflammatory cytokines/chemokines, immune cell infiltration in the colon, and tissue injury in C. rodentium-infected mice. Mechanistically, the NleC cleavage-generated p65¹⁻³⁸ fragment interferes with the interaction between p65 and ribosomal protein S3 (RPS3), a 'specifier' subunit of NF-κB that confers a subset of proinflammatory gene transcription, which amplifies the effect of cleaving only a small percentage of p65 to modulate NF-κB-mediated gene expression. Thus, our results reveal a novel mechanism for A/E pathogens to specifically block NF-κB signaling and inflammatory responses by cleaving a small percentage of p65 and targeting the p65/RPS3 interaction in host cells, thus providing novel insights into the pathogenic mechanisms of foodborne diseases.
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Affiliation(s)
- Andrea Hodgson
- W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Eric M. Wier
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Kai Fu
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Xin Sun
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Hongbing Yu
- Division of Gastroenterology, Department of Pediatrics, BC’s Children’s Hospital and Child and Family Research Institute, Vancouver, British Columbia, Canada
| | - Wenxin Zheng
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Ho Pan Sham
- Division of Gastroenterology, Department of Pediatrics, BC’s Children’s Hospital and Child and Family Research Institute, Vancouver, British Columbia, Canada
| | - Kaitlin Johnson
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Scott Bailey
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Bruce A. Vallance
- Division of Gastroenterology, Department of Pediatrics, BC’s Children’s Hospital and Child and Family Research Institute, Vancouver, British Columbia, Canada
| | - Fengyi Wan
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
- Department of Oncology, Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University, Baltimore, Maryland, United States of America
- * E-mail:
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Santos AS, Finlay BB. Bringing down the host: enteropathogenic and enterohaemorrhagic Escherichia coli effector-mediated subversion of host innate immune pathways. Cell Microbiol 2015; 17:318-32. [PMID: 25588886 DOI: 10.1111/cmi.12412] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2014] [Revised: 12/17/2014] [Accepted: 12/22/2014] [Indexed: 12/14/2022]
Abstract
Enteric bacterial pathogens commonly use a type III secretion system (T3SS) to successfully infect intestinal epithelial cells and survive and proliferate in the host. Enteropathogenic and enterohaemorrhagic Escherichia coli (EPEC; EHEC) colonize the human intestinal mucosa, form characteristic histological lesions on the infected epithelium and require the T3SS for full virulence. T3SS effectors injected into host cells subvert cellular pathways to execute a variety of functions within infected host cells. The EPEC and EHEC effectors that subvert innate immune pathways--specifically those involved in phagocytosis, host cell survival, apoptotic cell death and inflammatory signalling--are all required to cause disease. These processes are reviewed within, with a focus on recent work that has provided insights into the functions and host cell targets of these effectors.
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Affiliation(s)
- Andrew S Santos
- Department of Microbiology and Immunology, The University of British Columbia, Vancouver, BC, Canada; Michael Smith Laboratories, The University of British Columbia, Vancouver, BC, Canada
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Abstract
ABSTRACT
The inflammatory response is an integral part of host defense against enterohemorrhagic
Escherichia coli
(EHEC) infection and also contributes to disease pathology. In this article we explore the factors leading to inflammation during EHEC infection and the mechanisms EHEC and other attaching and effacing (A/E) pathogens have evolved to suppress inflammatory signaling. EHEC stimulates an inflammatory response in the intestine through host recognition of bacterial components such as flagellin and lipopolysaccharide. In addition, the activity of Shiga toxin and some type III secretion system effectors leads to increased tissue inflammation. Various infection models of EHEC and other A/E pathogens have revealed many of the immune factors that mediate this response. In particular, the outcome of infection is greatly influenced by the ability of an infected epithelial cell to mount an effective host inflammatory response. The inflammatory response of infected enterocytes is counterbalanced by the activity of type III secretion system effectors such as NleE and NleC that modify and inhibit components of the signaling pathways that lead to proinflammatory cytokine production. Overall, A/E pathogens have taught us that innate mucosal immune responses in the gastrointestinal tract during infection with A/E pathogens are highly complex and ultimate clearance of the pathogen depends on multiple factors, including inflammatory mediators, bacterial burden, and the function and integrity of resident intestinal epithelial cells.
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Turco MM, Sousa MC. The structure and specificity of the type III secretion system effector NleC suggest a DNA mimicry mechanism of substrate recognition. Biochemistry 2014; 53:5131-9. [PMID: 25040221 PMCID: PMC4131895 DOI: 10.1021/bi500593e] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
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Many pathogenic bacteria utilize
the type III secretion system
(T3SS) to translocate effector proteins directly into host cells,
facilitating colonization. In enterohemmorhagic Escherichia
coli (EHEC), a subset of T3SS effectors is essential for
suppression of the inflammatory response in hosts, including humans.
Identified as a zinc protease that cleaves NF-κB transcription
factors, NleC is one such effector. Here, we investigate NleC substrate
specificity, showing that four residues around the cleavage site in
the DNA-binding loop of the NF-κB subunit RelA strongly influence
the cleavage rate. Class I NF-κB subunit p50 is cleaved at a
reduced rate consistent with conservation of only three of these four
residues. However, peptides containing 10 residues on each side of
the scissile bond were not efficiently cleaved by NleC, indicating
that elements distal from the cleavage site are also important for
substrate recognition. We present the crystal structure of NleC and
show that it mimics DNA structurally and electrostatically. Consistent
with this model, mutation of phosphate-mimicking residues in NleC
reduces the level of RelA cleavage. We propose that global recognition
of NF-κB subunits by DNA mimicry combined with a high sequence
selectivity for the cleavage site results in exquisite NleC substrate
specificity. The structure also shows that despite undetectable similarity
of its sequence to those of other Zn2+ proteases beyond
its conserved HExxH Zn2+-binding motif, NleC is a member
of the Zincin protease superfamily, albeit divergent from its structural
homologues. In particular, NleC displays a modified Ψ-loop motif
that may be important for folding and refolding requirements implicit
in T3SS translocation.
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Affiliation(s)
- Michelle Marian Turco
- Department of Chemistry and Biochemistry, University of Colorado at Boulder , Boulder, Colorado 80309-0596, United States
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Giogha C, Lung TWF, Pearson JS, Hartland EL. Inhibition of death receptor signaling by bacterial gut pathogens. Cytokine Growth Factor Rev 2014; 25:235-43. [DOI: 10.1016/j.cytogfr.2013.12.012] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2013] [Accepted: 12/18/2013] [Indexed: 12/22/2022]
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Li W, Liu Y, Sheng X, Yin P, Hu F, Liu Y, Chen C, Li Q, Yan C, Wang J. Structure and mechanism of a type III secretion protease, NleC. ACTA ACUST UNITED AC 2013; 70:40-7. [PMID: 24419377 DOI: 10.1107/s1399004713024619] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2013] [Accepted: 09/03/2013] [Indexed: 11/10/2022]
Abstract
NleC is one of the virulence factors that is injected into infected host cells by enteropathogenic and enterohaemorrhagic Escherichia coli (EPEC and EHEC) via a needle-like protein complex called the type III secretion system (T3SS). The cytosolic NleC specifically cleaves the p65 subunit of NF-κB in the p65-p50 heterodimeric complex just after the Cys38 site in its N-terminal domain. The degradation of the remainder of the p65 C-terminal domain by the proteasome disrupts the NF-κB signalling pathway, thus dampening the host inflammatory response. Here, the crystal structure of NleC is reported at 1.55 Å resolution. In conjunction with biochemical analyses, the structure reveals that NleC is a member of the zincin zinc protease family and that the configuration of the NleC active site resembles that of the metzincin clan of metallopeptidases but without the canonical Met turn of astacin. The extended zinc-binding motif of NleC (HEXXHXXTXXXD) includes three metal ligands. The fifth zinc ligand, a conserved tyrosine (a bound water molecule is the fourth ligand), lies 45 residues downstream of the zincin motif. Furthermore, the electrostatic potential complementarity between NleC and p65 also contributes to the cleavage activity of the protease. These results not only provide important insights into the mechanism of how NleC recognizes its substrates, but also shed light on the design of new antibiotics for the food-borne diseases arising from EPEC and EHEC.
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Affiliation(s)
- Wenqi Li
- State Key Laboratory of Biomembrane and Membrane Biotechnology, School of Life Sciences, Tsinghua University, Beijing 100084, People's Republic of China
| | - Yexing Liu
- Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, People's Republic of China
| | - Xinlei Sheng
- Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, People's Republic of China
| | - Ping Yin
- Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, People's Republic of China
| | - Feizhuo Hu
- Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, People's Republic of China
| | - Ying Liu
- Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, People's Republic of China
| | - Chen Chen
- Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, People's Republic of China
| | - Quanxiu Li
- Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, People's Republic of China
| | - Chuangye Yan
- Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing 100084, People's Republic of China
| | - Jiawei Wang
- State Key Laboratory of Biomembrane and Membrane Biotechnology, School of Life Sciences, Tsinghua University, Beijing 100084, People's Republic of China
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Johannessen M, Askarian F, Sangvik M, Sollid JE. Bacterial interference with canonical NFκB signalling. MICROBIOLOGY-SGM 2013; 159:2001-2013. [PMID: 23873783 PMCID: PMC3799228 DOI: 10.1099/mic.0.069369-0] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The human body is constantly challenged by a variety of commensal and pathogenic micro-organisms that trigger the immune system. Central in the first line of defence is the pattern-recognition receptor (PRR)-induced stimulation of the NFκB pathway, leading to NFκB activation. The subsequent production of pro-inflammatory cytokines and/or antimicrobial peptides results in recruitment of professional phagocytes and bacterial clearance. To overcome this, bacteria have developed mechanisms for targeted interference in every single step in the PRR–NFκB pathway to dampen host inflammatory responses. This review aims to briefly overview the PRR–NFκB pathway in relation to the immune response and give examples of the diverse bacterial evasion mechanisms including changes in the bacterial surface, decoy production and injection of effector molecules. Targeted regulation of inflammatory responses is needed and bacterial molecules developed for immune evasion could provide future anti-inflammatory agents.
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Affiliation(s)
- Mona Johannessen
- Research Group of Host-Microbe Interactions, Department of Medical Biology, Faculty of Health Sciences, University of Tromsø, Tromsø, Norway
| | - Fatemeh Askarian
- Research Group of Host-Microbe Interactions, Department of Medical Biology, Faculty of Health Sciences, University of Tromsø, Tromsø, Norway
| | - Maria Sangvik
- Research Group of Host-Microbe Interactions, Department of Medical Biology, Faculty of Health Sciences, University of Tromsø, Tromsø, Norway
| | - Johanna E Sollid
- Research Group of Host-Microbe Interactions, Department of Medical Biology, Faculty of Health Sciences, University of Tromsø, Tromsø, Norway
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Structural basis of eukaryotic cell targeting by type III secretion system (T3SS) effectors. Res Microbiol 2013; 164:605-19. [PMID: 23541478 DOI: 10.1016/j.resmic.2013.03.019] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Accepted: 02/27/2013] [Indexed: 02/06/2023]
Abstract
Type III secretion systems (T3SS) are macromolecular complexes that translocate a wide number of effector proteins into eukaryotic host cells. Once within the cytoplasm, many T3SS effectors mimic the structure and/or function of eukaryotic proteins in order to manipulate signaling cascades, and thus play pivotal roles in colonization, invasion, survival and virulence. Structural biology techniques have played key roles in the unraveling of bacterial strategies employed for mimicry and targeting. This review provides an overall view of our current understanding of structure and function of T3SS effectors, as well as of the different classes of eukaryotic proteins that are targeted and the consequences for the infected cell.
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40
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Wier EM, Neighoff J, Sun X, Fu K, Wan F. Identification of an N-terminal truncation of the NF-κB p65 subunit that specifically modulates ribosomal protein S3-dependent NF-κB gene expression. J Biol Chem 2012; 287:43019-29. [PMID: 23115242 DOI: 10.1074/jbc.m112.388694] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
NF-κB is a pleiotrophic transcription factor that plays a prominent regulatory role in various cellular processes. Although previous efforts have focused on its activation, how NF-κB selects specific target genes in response to discrete signals remains puzzling. In addition to the well defined Rel protein components of NF-κB, the ribosomal protein S3 (RPS3) was identified to be an essential component of specific NF-κB complexes. RPS3 synergistically interacts with the NF-κB p65 subunit to achieve optimal binding and transactivation of a subset of NF-κB target genes, thus providing regulatory specificity. Emerging evidence suggests an important role for the RPS3-p65 interaction in context-specific NF-κB gene transcription. The food-borne pathogen Escherichia coli O157:H7 impacts the transcription of a subset of NF-κB target genes encoding proinflammatory cytokines and chemokines in host cells by preventing the nuclear translocation of RPS3, but not p65. The N terminus of p65 is crucial for RPS3 binding. Although several p65 N-terminal fragments are generated by either protease cleavage or alternative mRNA splicing under certain pathophysiological conditions, the role of these fragments in modulating NF-κB signaling, in particular RPS3-dependent selective gene transcription, has not been fully characterized. Here we report that an N-terminal fragment of p65 (amino acids 21-186) can selectively modulate NF-κB gene transcription by competing for RPS3 binding to p65. This 21-186 fragment preferentially localizes in the cytoplasm where it delays stimuli-induced RPS3 nuclear translocation, without affecting the nuclear translocation of p65. Our findings thus uncover a new cytoplasmic function for the N-terminal domain of p65 and provide a novel strategy for selective inhibition of NF-κB gene transcription.
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Affiliation(s)
- Eric M Wier
- Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, The Johns Hopkins University, Baltimore, Maryland 21205, USA
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41
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A distinct regulatory sequence is essential for the expression of a subset of nle genes in attaching and effacing Escherichia coli. J Bacteriol 2012; 194:5589-603. [PMID: 22904277 DOI: 10.1128/jb.00190-12] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Enteropathogenic Escherichia coli uses a type III secretion system (T3SS), encoded in the locus of enterocyte effacement (LEE) pathogenicity island, to translocate a wide repertoire of effector proteins into the host cell in order to subvert cell signaling cascades and promote bacterial colonization and survival. Genes encoding type III-secreted effectors are located in the LEE and scattered throughout the chromosome. While LEE gene regulation is better understood, the conditions and factors involved in the expression of effectors encoded outside the LEE are just starting to be elucidated. Here, we identified a highly conserved sequence containing a 13-bp inverted repeat (IR), located upstream of a subset of genes coding for different non-LEE-encoded effectors in A/E pathogens. Site-directed mutagenesis and deletion analysis of the nleH1 and nleB2 regulatory regions revealed that this IR is essential for the transcriptional activation of both genes. Growth conditions that favor the expression of LEE genes also facilitate the activation of nleH1 and nleB2; however, their expression is independent of the LEE-encoded positive regulators Ler and GrlA but is repressed by GrlR and the global regulator H-NS. In contrast, GrlA and Ler are required for nleA expression, while H-NS silences it. Consistent with their role in the regulation of nleA, purified Ler and H-NS bound to the regulatory region of nleA upstream of its promoter. This work shows that at least two modes of regulation control the expression of effector genes in attaching and effacing (A/E) pathogens, suggesting that a subset of effector functions may be coordinately expressed in a particular niche or time during infection.
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42
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Shames SR, Finlay BB. Bacterial effector interplay: a new way to view effector function. Trends Microbiol 2012; 20:214-9. [DOI: 10.1016/j.tim.2012.02.007] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2011] [Revised: 02/14/2012] [Accepted: 02/21/2012] [Indexed: 11/16/2022]
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43
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Functional differences and interactions between the Escherichia coli type III secretion system effectors NleH1 and NleH2. Infect Immun 2012; 80:2133-40. [PMID: 22451523 DOI: 10.1128/iai.06358-11] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The human pathogens enterohemorrhagic and enteropathogenic Escherichia coli (EHEC and EPEC), as well as the related mouse pathogen Citrobacter rodentium, utilize a type III secretion system (T3SS) to inject multiple effector proteins into host cells. The E. coli O157:H7 strain EDL933 carries two copies of non-locus of enterocyte effacement (LEE)-encoded protein H, designated NleH1 and NleH2, both of which bind to the human ribosomal protein S3 (RPS3), a subunit of NF-κB transcriptional complexes. In this study, we describe significant functional differences between NleH1 and NleH2 in their ability to regulate the host NF-κB pathway. We show that the EHEC and EPEC NleH effectors are functionally equivalent in their ability to affect RPS3 nuclear translocation. NleH1, but not NleH2, inhibited NF-κB activity without altering the kinetics of IκBα phosphorylation/degradation. We also determined that the class I PSD-95/Disc Large/ZO-1 (PDZ)-binding domain of NleH was important for its activity in the NF-κB pathway. In addition to binding RPS3, we found that NleH1 and NleH2 are able to bind to each other in vitro and in vivo, suggesting an additional mechanism by which the E. coli NleH effectors may regulate the extent and duration of NF-κB activation after their T3SS-dependent translocation. We also performed mouse infection experiments and established that mouse mortality and Citrobacter colonization were reduced in mice infected with ΔnleH. Complementing ΔnleH with NleH1 restored Citrobacter virulence and colonization to wild-type levels, whereas complementing with NleH2 reduced them. Taken together, our data show that NleH1 and NleH2 have pronounced functional differences in their ability to alter host transcriptional responses to bacterial infection.
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Abstract
Serine proteases, cysteine proteases, aspartic proteases and matrix metalloproteinases play an essential role in extracellular matrix remodeling and turnover through their proteolytic action on collagens, proteoglycans, fibronectin, elastin and laminin. Proteases can also act on chemokines, receptors and anti-microbial peptides, often potentiating their activity. The intestinal mucosa is the largest interface between the external environment and the tissues of the human body and is constantly exposed to proteolytic enzymes from many sources, including bacteria in the intestinal lumen, fibroblasts and immune cells in the lamina propria and enterocytes. Controlled proteolytic activity is crucial for the maintenance of gut immune homeostasis, for normal tissue turnover and for the integrity of the gut barrier. However, in intestinal immune-mediated disorders, pro-inflammatory cytokines induce the up-regulation of proteases, which become the end-stage effectors of mucosal damage by destroying the epithelium and basement membrane integrity and degrading the extracellular matrix of the lamina propria to produce ulcers. Protease-mediated barrier disruption in turn results in increased amounts of antigen crossing into the lamina propria, driving further immune responses and sustaining the inflammatory process.
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45
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Böhm A, Papenfort K, Lopez D, Vogel J. Microbes at their best: first Mol Micro Meeting Würzburg. Mol Microbiol 2011; 82:797-806. [DOI: 10.1111/j.1365-2958.2011.07852.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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