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Sharma AK, El Andaloussi A, Ismail N. Evasion of host antioxidative response via disruption of NRF2 signaling in fatal Ehrlichia-induced liver injury. PLoS Pathog 2023; 19:e1011791. [PMID: 37956169 PMCID: PMC10681308 DOI: 10.1371/journal.ppat.1011791] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Revised: 11/27/2023] [Accepted: 10/30/2023] [Indexed: 11/15/2023] Open
Abstract
Ehrlichia is Gram negative obligate intracellular bacterium that cause human monocytotropic ehrlichiosis (HME). HME is characterized by acute liver damage and inflammation that may progress to fatal toxic shock. We previously showed that fatal ehrlichiosis is due to deleterious activation of inflammasome pathways, which causes excessive inflammation and liver injury. Mammalian cells have developed mechanisms to control oxidative stress via regulation of nuclear factor erythroid 2 related 2 (NRF2) signaling. However, the contribution of NRF2 signaling to Ehrlichia-induced inflammasome activation and liver damage remains elusive. In this study, we investigated the contribution of NRF2 signaling in hepatocytes (HCs) to the pathogenesis of Ehrlichia-induced liver injury following infection with virulent Ixodes ovatus Ehrlichia (IOE, AKA E. japonica). Employing murine model of fatal ehrlichiosis, we found that virulent IOE inhibited NRF2 signaling in liver tissue of infected mice and in HCs as evidenced by downregulation of NRF2 expression, and downstream target GPX4, as well as decreased NRF2 nuclear translocation, a key step in NRF2 activation. This was associated with activation of non-canonical inflammasomes pathway marked by activation of caspase 11, accumulation of reactive oxygen species (ROS), mitochondrial dysfunction, and endoplasmic reticulum (ER) stress. Mechanistically, treatment of IOE-infected HCs with the antioxidant 3H-1,2-Dithiole-3-Thione (D3T), that induces NRF2 activation, attenuated oxidative stress and caspase 11 activation, as well as restored cell viability. Importantly, treatment of IOE-infected mice with D3T resulted in attenuated liver pathology, decreased inflammation, enhanced bacterial clearance, prolonged survival, and resistance to fatal ehrlichiosis. Our study reveals, for the first time, that targeting anti-oxidative signaling pathway is a key approach in the treatment of severe and potential Ehrlichia-induced acute liver injury and sepsis.
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Affiliation(s)
- Aditya Kumar Sharma
- Department of Pathology, College of Medicine, University of Illinois at Chicago, Chicago, Illinois, United States of America
| | - Abdeljabar El Andaloussi
- Department of Pathology, College of Medicine, University of Illinois at Chicago, Chicago, Illinois, United States of America
- BioImmune Solutions Inc., 605–1355, Le Corbusier, Laval, Quebec, Canada
| | - Nahed Ismail
- Department of Pathology, College of Medicine, University of Illinois at Chicago, Chicago, Illinois, United States of America
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2
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Van Roy Z, Shi W, Kak G, Duan B, Kielian T. Epigenetic Regulation of Leukocyte Inflammatory Mediator Production Dictates Staphylococcus aureus Craniotomy Infection Outcome. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2023; 211:414-428. [PMID: 37314520 PMCID: PMC10524781 DOI: 10.4049/jimmunol.2300050] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/23/2023] [Accepted: 05/18/2023] [Indexed: 06/15/2023]
Abstract
Staphylococcus aureus is a common cause of surgical-site infections, including those arising after craniotomy, which is performed to access the brain for the treatment of tumors, epilepsy, or hemorrhage. Craniotomy infection is characterized by complex spatial and temporal dynamics of leukocyte recruitment and microglial activation. We recently identified unique transcriptional profiles of these immune populations during S. aureus craniotomy infection. Epigenetic processes allow rapid and reversible control over gene transcription; however, little is known about how epigenetic pathways influence immunity to live S. aureus. An epigenetic compound library screen identified bromodomain and extraterminal domain-containing (BET) proteins and histone deacetylases (HDACs) as critical for regulating TNF, IL-6, IL-10, and CCL2 production by primary mouse microglia, macrophages, neutrophils, and granulocytic myeloid-derived suppressor cells in response to live S. aureus. Class I HDACs (c1HDACs) were increased in these cell types in vitro and in vivo during acute disease in a mouse model of S. aureus craniotomy infection. However, substantial reductions in c1HDACs were observed during chronic infection, highlighting temporal regulation and the importance of the tissue microenvironment for dictating c1HDAC expression. Microparticle delivery of HDAC and BET inhibitors in vivo caused widespread decreases in inflammatory mediator production, which significantly increased bacterial burden in the brain, galea, and bone flap. These findings identify histone acetylation as an important mechanism for regulating cytokine and chemokine production across diverse immune cell lineages that is critical for bacterial containment. Accordingly, aberrant epigenetic regulation may be important for promoting S. aureus persistence during craniotomy infection.
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Affiliation(s)
- Zachary Van Roy
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE 68198
| | - Wen Shi
- Mary & Dick Holland Regenerative Medicine Program; Division of Cardiology, Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE 68198
| | - Gunjan Kak
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE 68198
| | - Bin Duan
- Mary & Dick Holland Regenerative Medicine Program; Division of Cardiology, Department of Internal Medicine, University of Nebraska Medical Center, Omaha, NE 68198
| | - Tammy Kielian
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE 68198
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3
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Bui DC, Luo T, McBride JW. Type 1 secretion system and effectors in Rickettsiales. Front Cell Infect Microbiol 2023; 13:1175688. [PMID: 37256108 PMCID: PMC10225607 DOI: 10.3389/fcimb.2023.1175688] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Accepted: 05/02/2023] [Indexed: 06/01/2023] Open
Abstract
Obligate intracellular bacteria in the order Rickettsiales are transmitted by arthropod vectors and cause life-threatening infections in humans and animals. While both type 1 and type 4 secretion systems (T1SS and T4SS) have been identified in this group, the most extensive studies of Rickettsiales T1SS and associated effectors have been performed in Ehrlichia. These studies have uncovered important roles for the T1SS effectors in pathobiology and immunity. To evade innate immune responses and promote intracellular survival, Ehrlichia and other related obligate pathogens secrete multiple T1SS effectors which interact with a diverse network of host targets associated with essential cellular processes. T1SS effectors have multiple functional activities during infection including acting as nucleomodulins and ligand mimetics that activate evolutionarily conserved cellular signaling pathways. In Ehrlichia, an array of newly defined major immunoreactive proteins have been identified that are predicted as T1SS substrates and have conformation-dependent antibody epitopes. These findings highlight the underappreciated and largely uncharacterized roles of T1SS effector proteins in pathobiology and immunity. This review summarizes current knowledge regarding roles of T1SS effectors in Rickettsiales members during infection and explores newly identified immunoreactive proteins as potential T1SS substrates and targets of a protective host immune response.
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Affiliation(s)
- Duc-Cuong Bui
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, United States
| | - Tian Luo
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, United States
| | - Jere W. McBride
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, United States
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, United States
- Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, TX, United States
- Sealy Institute for Vaccine Sciences, University of Texas Medical Branch, Galveston, TX, United States
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, United States
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4
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Kim Y, Wang J, Clemens EG, Grab DJ, Dumler JS. Anaplasma phagocytophilum Ankyrin A Protein (AnkA) Enters the Nucleus Using an Importin-β-, RanGTP-Dependent Mechanism. Front Cell Infect Microbiol 2022; 12:828605. [PMID: 35719343 PMCID: PMC9204287 DOI: 10.3389/fcimb.2022.828605] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Accepted: 04/20/2022] [Indexed: 12/30/2022] Open
Abstract
Anaplasma phagocytophilum, a tick-borne obligately intracellular bacterium of neutrophils, causes human granulocytic anaplasmosis. Ankyrin A (AnkA), an effector protein with multiple ankyrin repeats (AR) is injected via type IV-secretion into the host neutrophil to gain access to the nucleus where it modifies the epigenome to promote microbial fitness and propagation. AR proteins transported into the host cell nucleus must use at least one of two known eukaryotic pathways, the classical importin β-dependent pathway, and/or the RanGDP- and AR (ankyrin-repeat)-dependent importin β-independent (RaDAR) pathway. Truncation of the first four AnkA N-terminal ARs (AR1-4), but not other regions, prevents AnkA nuclear accumulation. To investigate the mechanism of nuclear import, we created point mutations of AnkA N-terminal ARs, predicted to interfere with RaDAR protein import, and used importazole, a specific inhibitor of the importin α/β, RanGTP-dependent pathway. Nuclear colocalization analysis shows that nuclear localization of AnkA is unaffected by single AR1-4 mutations but is significantly reduced by single mutations in consecutive ARs suggesting RaDAR protein nuclear import. However, AnkA nuclear localization was also decreased with importazole, and with GTPγS. Furthermore, A. phagocytophilum growth in HL-60 cells was completely suppressed with importazole, indicating that A. phagocytophilum propagation requires a β-importin-dependent pathway. A typical classical NLS overlapping AR4 was subsequently identified suggesting the primacy of the importin-α/β system in AnkA nuclear localization. Whether the mutational studies of putative key residues support RaDAR NLS function or simply reflect structural changes that diminish engagement of an AR-NLS-importin pathway needs to be resolved through careful structure-function studies.
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Affiliation(s)
- Yuri Kim
- Department of Pathology, Uniformed Services University of the Health Sciences, Bethesda, MD, United States,Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, United States
| | - Jianyang Wang
- Department of Pathology, Uniformed Services University of the Health Sciences, Bethesda, MD, United States,Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, MD, United States
| | - Emily G. Clemens
- Department of Pathology, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
| | - Dennis J. Grab
- Department of Pathology, Uniformed Services University of the Health Sciences, Bethesda, MD, United States
| | - J. Stephen Dumler
- Department of Pathology, Uniformed Services University of the Health Sciences, Bethesda, MD, United States,*Correspondence: J. Stephen Dumler,
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5
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Rajeev R, Dwivedi AP, Sinha A, Agarwaal V, Dev RR, Kar A, Khosla S. Epigenetic interaction of microbes with their mammalian hosts. J Biosci 2021. [PMID: 34728591 PMCID: PMC8550911 DOI: 10.1007/s12038-021-00215-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
The interaction of microbiota with its host has the ability to alter the cellular functions of both, through several mechanisms. Recent work, from many laboratories including our own, has shown that epigenetic mechanisms play an important role in the alteration of these cellular functions. Epigenetics broadly refers to change in the phenotype without a corresponding change in the DNA sequence. This change is usually brought by epigenetic modifications of the DNA itself, the histone proteins associated with the DNA in the chromatin, non-coding RNA or the modifications of the transcribed RNA. These modifications, also known as epigenetic code, do not change the DNA sequence but alter the expression level of specific genes. Microorganisms seem to have learned how to modify the host epigenetic code and modulate the host transcriptome in their favour. In this review, we explore the literature that describes the epigenetic interaction of bacteria, fungi and viruses, with their mammalian hosts.
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6
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Byerly CD, Patterson LL, McBride JW. Ehrlichia TRP effectors: moonlighting, mimicry and infection. Pathog Dis 2021; 79:6261440. [PMID: 33974702 PMCID: PMC8112483 DOI: 10.1093/femspd/ftab026] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Accepted: 04/29/2021] [Indexed: 12/24/2022] Open
Abstract
Intracellular bacteria have evolved various strategies to evade host defense mechanisms. Remarkably, the obligately intracellular bacterium, Ehrlichia chaffeensis, hijacks host cell processes of the mononuclear phagocyte to evade host defenses through mechanisms executed in part by tandem repeat protein (TRP) effectors secreted by the type 1 secretion system. In the past decade, TRP120 has emerged as a model moonlighting effector, acting as a ligand mimetic, nucleomodulin and ubiquitin ligase. These defined functions illuminate the diverse roles TRP120 plays in exploiting and manipulating host cell processes, including cytoskeletal organization, vesicle trafficking, cell signaling, transcriptional regulation, post-translational modifications, autophagy and apoptosis. This review will focus on TRP effectors and their expanding roles in infection and provide perspective on Ehrlichia chaffeensis as an invaluable model organism for understanding infection strategies of obligately intracellular bacteria.
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Affiliation(s)
- Caitlan D Byerly
- Departments of Pathology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - LaNisha L Patterson
- Departments of Pathology, University of Texas Medical Branch, Galveston, TX 77555, USA
| | - Jere W McBride
- Departments of Pathology, University of Texas Medical Branch, Galveston, TX 77555, USA.,Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX 77555, USA.,Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, TX 77555, USA.,Sealy Institute for Vaccine Sciences, University of Texas Medical Branch, Galveston, TX 77555, USA.,Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX 77555, USA
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7
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Patterson LL, Byerly CD, McBride JW. Anaplasmataceae: Dichotomous Autophagic Interplay for Infection. Front Immunol 2021; 12:642771. [PMID: 33912170 PMCID: PMC8075259 DOI: 10.3389/fimmu.2021.642771] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2020] [Accepted: 03/15/2021] [Indexed: 12/19/2022] Open
Abstract
Autophagy is a vital conserved degradative process that maintains cellular homeostasis by recycling or eliminating dysfunctional cellular organelles and proteins. More recently, autophagy has become a well-recognized host defense mechanism against intracellular pathogens through a process known as xenophagy. On the host-microbe battlefield many intracellular bacterial pathogens have developed the ability to subvert xenophagy to establish infection. Obligately intracellular bacterial pathogens of the Anaplasmataceae family, including Ehrlichia chaffeensis, Anaplasma phaogocytophilium and Orientia tsutsugamushi have developed a dichotomous strategy to exploit the host autophagic pathway to obtain nutrients while escaping lysosomal destruction for intracellular survival within the host cell. In this review, the recent findings regarding how these master manipulators engage and inhibit autophagy for infection are explored. Future investigation to understand mechanisms used by Anaplasmataceae to exploit autophagy may advance novel antimicrobial therapies and provide new insights into how intracellular microbes exploit autophagy to survive.
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Affiliation(s)
- LaNisha L Patterson
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, United States
| | - Caitlan D Byerly
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, United States
| | - Jere W McBride
- Department of Pathology, University of Texas Medical Branch, Galveston, TX, United States.,Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, TX, United States.,Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, TX, United States.,Sealy Institute for Vaccine Sciences, University of Texas Medical Branch, Galveston, TX, United States.,Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, TX, United States
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8
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Voss OH, Rahman MS. Rickettsia-host interaction: strategies of intracytosolic host colonization. Pathog Dis 2021; 79:ftab015. [PMID: 33705517 PMCID: PMC8023194 DOI: 10.1093/femspd/ftab015] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Accepted: 03/09/2021] [Indexed: 12/29/2022] Open
Abstract
Bacterial infection is a highly complex biological process involving a dynamic interaction between the invading microorganism and the host. Specifically, intracellular pathogens seize control over the host cellular processes including membrane dynamics, actin cytoskeleton, phosphoinositide metabolism, intracellular trafficking and immune defense mechanisms to promote their host colonization. To accomplish such challenging tasks, virulent bacteria deploy unique species-specific secreted effectors to evade and/or subvert cellular defense surveillance mechanisms to establish a replication niche. However, despite superficially similar infection strategies, diverse Rickettsia species utilize different effector repertoires to promote host colonization. This review will discuss our current understandings on how different Rickettsia species deploy their effector arsenal to manipulate host cellular processes to promote their intracytosolic life within the mammalian host.
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Affiliation(s)
- Oliver H Voss
- Department of Microbiology and Immunology, University of Maryland School of Medicine, HSF2, room 416, 20 Penn St, Baltimore, MD 21201, USA
| | - M Sayeedur Rahman
- Department of Microbiology and Immunology, University of Maryland School of Medicine, HSF2, room 416, 20 Penn St, Baltimore, MD 21201, USA
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9
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Lin M, Xiong Q, Chung M, Daugherty SC, Nagaraj S, Sengamalay N, Ott S, Godinez A, Tallon LJ, Sadzewicz L, Fraser C, Dunning Hotopp JC, Rikihisa Y. Comparative Analysis of Genome of Ehrlichia sp. HF, a Model Bacterium to Study Fatal Human Ehrlichiosis. BMC Genomics 2021; 22:11. [PMID: 33407096 PMCID: PMC7789307 DOI: 10.1186/s12864-020-07309-z] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 12/07/2020] [Indexed: 12/16/2022] Open
Abstract
BACKGROUND The genus Ehrlichia consists of tick-borne obligatory intracellular bacteria that can cause deadly diseases of medical and agricultural importance. Ehrlichia sp. HF, isolated from Ixodes ovatus ticks in Japan [also referred to as I. ovatus Ehrlichia (IOE) agent], causes acute fatal infection in laboratory mice that resembles acute fatal human monocytic ehrlichiosis caused by Ehrlichia chaffeensis. As there is no small laboratory animal model to study fatal human ehrlichiosis, Ehrlichia sp. HF provides a needed disease model. However, the inability to culture Ehrlichia sp. HF and the lack of genomic information have been a barrier to advance this animal model. In addition, Ehrlichia sp. HF has several designations in the literature as it lacks a taxonomically recognized name. RESULTS We stably cultured Ehrlichia sp. HF in canine histiocytic leukemia DH82 cells from the HF strain-infected mice, and determined its complete genome sequence. Ehrlichia sp. HF has a single double-stranded circular chromosome of 1,148,904 bp, which encodes 866 proteins with a similar metabolic potential as E. chaffeensis. Ehrlichia sp. HF encodes homologs of all virulence factors identified in E. chaffeensis, including 23 paralogs of P28/OMP-1 family outer membrane proteins, type IV secretion system apparatus and effector proteins, two-component systems, ankyrin-repeat proteins, and tandem repeat proteins. Ehrlichia sp. HF is a novel species in the genus Ehrlichia, as demonstrated through whole genome comparisons with six representative Ehrlichia species, subspecies, and strains, using average nucleotide identity, digital DNA-DNA hybridization, and core genome alignment sequence identity. CONCLUSIONS The genome of Ehrlichia sp. HF encodes all known virulence factors found in E. chaffeensis, substantiating it as a model Ehrlichia species to study fatal human ehrlichiosis. Comparisons between Ehrlichia sp. HF and E. chaffeensis will enable identification of in vivo virulence factors that are related to host specificity, disease severity, and host inflammatory responses. We propose to name Ehrlichia sp. HF as Ehrlichia japonica sp. nov. (type strain HF), to denote the geographic region where this bacterium was initially isolated.
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Affiliation(s)
- Mingqun Lin
- Department of Veterinary Biosciences, The Ohio State University, 1925 Coffey Road, Columbus, OH, 43210, USA.
| | - Qingming Xiong
- Department of Veterinary Biosciences, The Ohio State University, 1925 Coffey Road, Columbus, OH, 43210, USA
| | - Matthew Chung
- Institute for Genome Sciences, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD, 21201, USA
| | - Sean C Daugherty
- Institute for Genome Sciences, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD, 21201, USA
| | - Sushma Nagaraj
- Institute for Genome Sciences, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD, 21201, USA
| | - Naomi Sengamalay
- Institute for Genome Sciences, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD, 21201, USA
| | - Sandra Ott
- Institute for Genome Sciences, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD, 21201, USA
| | - Al Godinez
- Institute for Genome Sciences, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD, 21201, USA
| | - Luke J Tallon
- Institute for Genome Sciences, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD, 21201, USA
| | - Lisa Sadzewicz
- Institute for Genome Sciences, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD, 21201, USA
| | - Claire Fraser
- Institute for Genome Sciences, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD, 21201, USA
- Department of Medicine, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD, 21201, USA
| | - Julie C Dunning Hotopp
- Institute for Genome Sciences, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD, 21201, USA
- Department of Microbiology and Immunology, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD, 21201, USA
- Greenebaum Cancer Center, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD, 21201, USA
| | - Yasuko Rikihisa
- Department of Veterinary Biosciences, The Ohio State University, 1925 Coffey Road, Columbus, OH, 43210, USA.
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10
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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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11
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Rajeev R, Dwivedi AP, Sinha A, Agarwaal V, Dev RR, Kar A, Khosla S. Epigenetic interaction of microbes with their mammalian hosts. J Biosci 2021; 46:94. [PMID: 34728591 PMCID: PMC8550911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
The interaction of microbiota with its host has the ability to alter the cellular functions of both, through several mechanisms. Recent work, from many laboratories including our own, has shown that epigenetic mechanisms play an important role in the alteration of these cellular functions. Epigenetics broadly refers to change in the phenotype without a corresponding change in the DNA sequence. This change is usually brought by epigenetic modifications of the DNA itself, the histone proteins associated with the DNA in the chromatin, non-coding RNA or the modifications of the transcribed RNA. These modifications, also known as epigenetic code, do not change the DNA sequence but alter the expression level of specific genes. Microorganisms seem to have learned how to modify the host epigenetic code and modulate the host transcriptome in their favour. In this review, we explore the literature that describes the epigenetic interaction of bacteria, fungi and viruses, with their mammalian hosts.
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Affiliation(s)
- Ramisetti Rajeev
- grid.145749.a0000 0004 1767 2735Centre for DNA Fingerprinting and Diagnostics (CDFD), Hyderabad, India ,grid.411639.80000 0001 0571 5193Graduate Studies, Manipal Academy of Higher Education (MAHE), Manipal, India
| | - Ambey Prasad Dwivedi
- grid.145749.a0000 0004 1767 2735Centre for DNA Fingerprinting and Diagnostics (CDFD), Hyderabad, India ,grid.411639.80000 0001 0571 5193Graduate Studies, Manipal Academy of Higher Education (MAHE), Manipal, India
| | - Anunay Sinha
- grid.145749.a0000 0004 1767 2735Centre for DNA Fingerprinting and Diagnostics (CDFD), Hyderabad, India ,grid.502122.60000 0004 1774 5631Graduate Studies, Regional Centre for Biotechnology (RCB), Faridabad, India
| | - Viplove Agarwaal
- grid.145749.a0000 0004 1767 2735Centre for DNA Fingerprinting and Diagnostics (CDFD), Hyderabad, India
| | - Rachana Roshan Dev
- grid.145749.a0000 0004 1767 2735Centre for DNA Fingerprinting and Diagnostics (CDFD), Hyderabad, India
| | - Anjana Kar
- grid.145749.a0000 0004 1767 2735Centre for DNA Fingerprinting and Diagnostics (CDFD), Hyderabad, India
| | - Sanjeev Khosla
- grid.145749.a0000 0004 1767 2735Centre for DNA Fingerprinting and Diagnostics (CDFD), Hyderabad, India ,grid.417641.10000 0004 0504 3165Institute of Microbial Technology (IMTech), Chandigarh, India
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12
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Bacterial nucleomodulins and cancer: An unresolved enigma. Transl Oncol 2020; 14:100922. [PMID: 33137543 PMCID: PMC7644672 DOI: 10.1016/j.tranon.2020.100922] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 10/09/2020] [Accepted: 10/12/2020] [Indexed: 01/07/2023] Open
Abstract
Recent studies in microbial pathogenesis have identified several bacterial proteins with the potential to influence host cell nuclei. This field of research is in its infancy, however it is rapidly growing. In particular, the role of bacterial nucleomodulins in animal oncogenesis is an area that requires attention. Earlier research has suggested the role of nucleomodulins in plant tumor development and these findings may provide us with a better understanding of the role of these proteins in human cancer development. This proposition is further supported by previous identification of nucleomodulins present in bacteria that have been associated with cancer development, but their role in human cancer is unclear. In this article, we provide an update on the status of these nucleomodulins and their role in cancer etiology. We collected information about known bacterial nucleomodulins and tried to relate their mechanistic implication with already known plant tumor development model. The present research indicates that bacterial nucleomodulins may be an important target in cancer etiology and knowledge of their role in human oncogenesis may help us to create suitable alternative cancer management strategies.
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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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Chamberlain NB, Mehari YT, Hayes BJ, Roden CM, Kidane DT, Swehla AJ, Lorenzana-DeWitt MA, Farone AL, Gunderson JH, Berk SG, Farone MB. Infection and nuclear interaction in mammalian cells by 'Candidatus Berkiella cookevillensis', a novel bacterium isolated from amoebae. BMC Microbiol 2019; 19:91. [PMID: 31072343 PMCID: PMC6507137 DOI: 10.1186/s12866-019-1457-z] [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: 09/10/2017] [Accepted: 04/15/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND 'Candidatus Berkiella cookevillensis' and 'Ca. Berkiella aquae' have previously been described as intranuclear bacteria of amoebae. Both bacteria were isolated from amoebae and were described as appearing within the nuclei of Acanthamoeba polyphaga and ultimately lysing their host cells within 4 days. Both bacteria are Gammaproteobacteria in the order Legionellales with the greatest similarity to Coxiella burnetii. Neither bacterium grows axenically in artificial culture media. In this study, we further characterized 'Ca. B. cookevillensis' by demonstrating association with nuclei of human phagocytic and nonphagocytic cell lines. RESULTS Transmission electron microscopy (TEM) and confocal microscopy were used to confirm nuclear co-localization of 'Ca. B. cookevillensis' in the amoeba host A. polyphaga with 100% of cells having bacteria co-localized with host nuclei by 48 h. TEM and confocal microscopy demonstrated that the bacterium was also observed to be closely associated with nuclei of human U937 and THP-1 differentiated macrophage cell lines and nonphagocytic HeLa human epithelial-like cells. Immunofluorescent staining revealed that the bacteria-containing vacuole invaginates the nuclear membranes and appears to cross from the cytoplasm into the nucleus as an intact vacuole. CONCLUSION Results of this study indicate that a novel coccoid bacterium isolated from amoebae can infect human cell lines by associating with the host cell nuclei, either by crossing the nuclear membranes or by deeply invaginating the nuclear membranes. When associated with the nuclei, the bacteria appear to be bound within a vacuole and replicate to high numbers by 48 h. We believe this is the first report of such a process involving bacteria and human cell lines.
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Affiliation(s)
- Nicholas B Chamberlain
- Molecular Biosciences Program, Middle Tennessee State University, 1301 E. Main St, Murfreesboro, TN, 37130, USA.,Department of Biology, Middle Tennessee State University, 1301 E. Main St, Murfreesboro, TN, 37130, USA
| | - Yohannes T Mehari
- Molecular Biosciences Program, Middle Tennessee State University, 1301 E. Main St, Murfreesboro, TN, 37130, USA.,Department of Biology, Middle Tennessee State University, 1301 E. Main St, Murfreesboro, TN, 37130, USA
| | - B Jason Hayes
- Department of Biology, Middle Tennessee State University, 1301 E. Main St, Murfreesboro, TN, 37130, USA
| | - Colleen M Roden
- Department of Biology, Middle Tennessee State University, 1301 E. Main St, Murfreesboro, TN, 37130, USA
| | - Destaalem T Kidane
- Molecular Biosciences Program, Middle Tennessee State University, 1301 E. Main St, Murfreesboro, TN, 37130, USA.,Department of Biology, Middle Tennessee State University, 1301 E. Main St, Murfreesboro, TN, 37130, USA
| | - Andrew J Swehla
- Department of Biology, Middle Tennessee State University, 1301 E. Main St, Murfreesboro, TN, 37130, USA
| | - Mario A Lorenzana-DeWitt
- Department of Biology, Middle Tennessee State University, 1301 E. Main St, Murfreesboro, TN, 37130, USA
| | - Anthony L Farone
- Molecular Biosciences Program, Middle Tennessee State University, 1301 E. Main St, Murfreesboro, TN, 37130, USA.,Department of Biology, Middle Tennessee State University, 1301 E. Main St, Murfreesboro, TN, 37130, USA
| | - John H Gunderson
- Department of Biology, Tennessee Technological University, 1 William L Jones Dr, Cookeville, TN, 38505, USA
| | - Sharon G Berk
- Department of Biology, Middle Tennessee State University, 1301 E. Main St, Murfreesboro, TN, 37130, USA
| | - Mary B Farone
- Molecular Biosciences Program, Middle Tennessee State University, 1301 E. Main St, Murfreesboro, TN, 37130, USA. .,Department of Biology, Middle Tennessee State University, 1301 E. Main St, Murfreesboro, TN, 37130, USA.
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15
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Kondethimmanahalli C, Liu H, Ganta RR. Proteome Analysis Revealed Changes in Protein Expression Patterns Caused by Mutations in Ehrlichia chaffeensis. Front Cell Infect Microbiol 2019; 9:58. [PMID: 30937288 PMCID: PMC6431617 DOI: 10.3389/fcimb.2019.00058] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Accepted: 02/25/2019] [Indexed: 01/31/2023] Open
Abstract
The tick-borne rickettsial pathogen, Ehrlichia chaffeensis, causes monocytic ehrlichiosis in people and other vertebrate hosts. Mutational analysis in E. chaffeensis genome aids in better understanding of its infection and persistence in host cells and in the development of attenuated vaccines. Our recent RNA deep sequencing study revealed that three genomic mutations caused global changes in the gene expression patterns, which in turn affect the ability of pathogen's survival in a host and the host's ability to induce protection against the pathogen. In this follow-up study, we document the impact of mutations on the pathogen's global protein expression and the influence of protein abundance on a mutant's attenuation and protection of vertebrate host against infection. iTRAQ labeling and mass spectrometry analysis of E. chaffeensis wildtype and mutants identified 564 proteins covering about 63% of the genome. Mutation in ECH_0379 gene encoding for an antiporter protein, causing attenuated growth in vertebrate hosts, led to overexpression of p28 outer membrane proteins, molecular chaperons, and metabolic enzymes, while a mutation downstream to the ECH_0490 gene that caused minimal impact on the pathogen's in vivo growth resulted in major changes in the expression of outer membrane proteins, transcriptional regulators and T4SS proteins. ECH_0660 gene mutation, causing the pathogen's rapid clearance and offering protection against wild type infection challenge in a vertebrate host, had a minimal impact on proteome similar to our prior observations from transcriptome analysis. While the global proteome data revealed fewer translated proteins compared to the transcripts identified from RNA deep sequencing analysis, there is a great deal of correlation noted between the global proteome and transcriptome analysis. Further, global proteome analysis, including the assessment of 2D resolved total and immunoproteomes revealed greater variations in the highly immunogenic p28-Omp proteins.
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Affiliation(s)
- Chandramouli Kondethimmanahalli
- Department of Diagnostic Medicine/Pathobiology, Center of Excellence for Vector-Borne Diseases, College of Veterinary Medicine, Kansas State University, Manhattan, KS, United States
| | - Huitao Liu
- Department of Diagnostic Medicine/Pathobiology, Center of Excellence for Vector-Borne Diseases, College of Veterinary Medicine, Kansas State University, Manhattan, KS, United States
| | - Roman R Ganta
- Department of Diagnostic Medicine/Pathobiology, Center of Excellence for Vector-Borne Diseases, College of Veterinary Medicine, Kansas State University, Manhattan, KS, United States
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Kibler CE, Milligan SL, Farris TR, Zhu B, Mitra S, McBride JW. Ehrlichia chaffeensis TRP47 enters the nucleus via a MYND-binding domain-dependent mechanism and predominantly binds enhancers of host genes associated with signal transduction, cytoskeletal organization, and immune response. PLoS One 2018; 13:e0205983. [PMID: 30408047 PMCID: PMC6224051 DOI: 10.1371/journal.pone.0205983] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2018] [Accepted: 10/04/2018] [Indexed: 12/14/2022] Open
Abstract
Ehrlichia chaffeensis is an obligately intracellular bacterium that establishes infection in mononuclear phagocytes through largely undefined reprogramming strategies including modulation of host gene transcription. In this study, we demonstrate that the E. chaffeensis effector TRP47 enters the host cell nucleus and binds regulatory regions of host genes relevant to infection. TRP47 was observed in the nucleus of E. chaffeensis-infected host cells, and nuclear localization was dependent on a variant MYND-binding domain. An electrophoretic mobility shift assay (EMSA) demonstrated that TRP47 directly binds host DNA via its tandem repeat domain. Utilizing chromatin immunoprecipitation followed by high-throughput DNA sequencing (ChIP-seq) with E. chaffeensis-infected cells, TRP47 was found to bind at multiple sites in the human genome (n = 2,051 at p < 10-30). Ontology analysis identified genes involved in functions such as immune response, cytoskeletal organization, and signal transduction. TRP47-bound genes included RNA-coding genes, many of these linked to cell proliferation or apoptosis. Comparison of TRP47 binding sites with those of previously-identified E. chaffeensis nucleomodulins identified multiple genes and gene functional categories in common including intracellular transport, cell signaling, and transcriptional regulation. Further, motif analysis followed by EMSA with synthetic oligonucleotides containing discovered motifs revealed a conserved TRP47 DNA-binding motif. This study reveals that TRP47 is a nucleomodulin that enters the nucleus via a MYND-binding domain and appears to play a role in host cell reprogramming by regulation of transcription.
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Affiliation(s)
- Clayton E. Kibler
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Sarah L. Milligan
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Tierra R. Farris
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Bing Zhu
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Shubhajit Mitra
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
| | - Jere W. McBride
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas, United States of America
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas, United States of America
- Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, Texas, United States of America
- Sealy Center for Vaccine Development, University of Texas Medical Branch, Galveston, Texas, United States of America
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, Texas, United States of America
- * E-mail:
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The Rickettsial Ankyrin Repeat Protein 2 Is a Type IV Secreted Effector That Associates with the Endoplasmic Reticulum. mBio 2018; 9:mBio.00975-18. [PMID: 29946049 PMCID: PMC6020290 DOI: 10.1128/mbio.00975-18] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Strains of Rickettsia rickettsii, the tick-borne agent of Rocky Mountain spotted fever, vary considerably in virulence. Genomic comparisons of R. rickettsii strains have identified a relatively small number of genes divergent in an avirulent strain. Among these is one annotated as Rickettsia ankyrin repeat protein 2 (RARP-2). Homologs of RARP-2 are present in all strains of R. rickettsii, but the protein in the avirulent strain Iowa contains a large internal deletion relative to the virulent Sheila Smith strain. RARP-2 is secreted in a type IV secretion system-dependent manner and exposed to the host cell cytosol. RARP-2 of Sheila Smith colocalizes with multilamellar membranous structures bearing markers of the endoplasmic reticulum (ER), whereas the Iowa protein shows no colocalization with host cell organelles and evidence of proteolytic degradation is detected. Overexpression of Sheila Smith RARP-2 in R. rickettsii Iowa converts this avirulent strain’s typically nonlytic or opaque plaque type to a lytic plaque phenotype similar to that of the virulent Sheila Smith strain. Mutation of a predicted proteolytic active site of Sheila Smith RARP-2 abolished the lytic plaque phenotype but did not eliminate association with host membrane. RARP-2 is thus a type IV secreted effector and released from the rickettsiae into the host cytosol to modulate host processes during infection. Overexpression of Sheila Smith RARP-2 did not, however, restore the virulence of the Iowa strain in a guinea pig model, likely due to the multifactorial nature of rickettsial virulence. Members of the genus Rickettsia are obligate intracellular bacteria that exhibit a range of virulence from harmless endosymbionts of arthropods to the etiologic agents of severe disease. Despite the growing number of available genomes, little is known regarding virulence determinants of rickettsiae. Here, we have characterized an ankyrin repeat-containing protein, RARP-2, which differs between a highly virulent and an avirulent strain of R. rickettsii, the agent of Rocky Mountain spotted fever. RARP-2 is secreted by a type IV secretion system into the cytosol of the host cell, where it interacts with and manipulates the structure of the endoplasmic reticulum. RARP-2 from the avirulent strain is truncated by the loss of seven of 10 ankyrin repeat units but, although secreted, fails to alter ER structure. Recognition of those rickettsial factors associated with virulence will facilitate understanding of regional and strain-specific variation in severity of disease.
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18
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Kondethimmanahalli C, Ganta R. Impact of Three Different Mutations in Ehrlichia chaffeensis in Altering the Global Gene Expression Patterns. Sci Rep 2018; 8:6162. [PMID: 29670161 PMCID: PMC5906474 DOI: 10.1038/s41598-018-24471-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Accepted: 03/26/2018] [Indexed: 02/06/2023] Open
Abstract
The rickettsial pathogen Ehrlichia chaffeensis causes a tick-borne disease, human monocytic ehrlichiosis. Mutations within certain genomic locations of the pathogen aid in understanding the pathogenesis and in developing attenuated vaccines. Our previous studies demonstrated that mutations in different genomic sites in E. chaffeensis caused variable impacts on their growth and attenuation in vertebrate and tick hosts. Here, we assessed the effect of three mutations on transcriptional changes using RNA deep-sequencing technology. RNA sequencing aided in detecting 66-80% of the transcripts of wildtype and mutant E. chaffeensis. Mutation in an antiporter gene (ECH_0379) causing attenuated growth in vertebrate hosts resulted in the down regulation of many transcribed genes. Similarly, a mutation downstream to the ECH_0490 coding sequence resulted in minimal impact on the pathogen's in vivo growth, but caused major changes in its transcriptome. This mutation caused enhanced expression of several host stress response genes. Even though the ECH_0660 gene mutation caused the pathogen's rapid clearance in vertebrate hosts and aids in generating a protective response, there was minimal impact on the transcriptome. The transcriptomic data offer novel insights about the impact of mutations on global gene expression and how they may contribute to the pathogen's resistance and/or clearance from the host.
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Affiliation(s)
- Chandramouli Kondethimmanahalli
- Center of Excellence for Vector-Borne Diseases, Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas, 66506, USA
| | - Roman Ganta
- Center of Excellence for Vector-Borne Diseases, Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas, 66506, USA.
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19
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Díaz FE, Abarca K, Kalergis AM. An Update on Host-Pathogen Interplay and Modulation of Immune Responses during Orientia tsutsugamushi Infection. Clin Microbiol Rev 2018; 31:e00076-17. [PMID: 29386235 PMCID: PMC5967693 DOI: 10.1128/cmr.00076-17] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The obligate intracellular bacterium Orientia tsutsugamushi is the causative agent of scrub typhus in humans, a serious mite-borne disease present in a widespread area of endemicity, which affects an estimated 1 million people every year. This disease may exhibit a broad range of presentations, ranging from asymptomatic to fatal conditions, with the latter being due to disseminated endothelial infection and organ injury. Unique characteristics of the biology and host-pathogen interactions of O. tsutsugamushi, including the high antigenic diversity among strains and the highly variable, short-lived memory responses developed by the host, underlie difficulties faced in the pursuit of an effective vaccine, which is an imperative need. Other factors that have hindered scientific progress relative to the infectious mechanisms of and the immune response triggered by this bacterium in vertebrate hosts include the limited number of mechanistic studies performed on animal models and the lack of genetic tools currently available for this pathogen. However, recent advances in animal model development are promising to improve our understanding of host-pathogen interactions. Here, we comprehensively discuss the recent advances in and future perspectives on host-pathogen interactions and the modulation of immune responses related to this reemerging disease, highlighting the role of animal models.
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Affiliation(s)
- Fabián E Díaz
- Millennium Institute on Immunology and Immunotherapy, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Katia Abarca
- Departamento en Enfermedades Infecciosas e Inmunología Pediátricas, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Alexis M Kalergis
- Millennium Institute on Immunology and Immunotherapy, Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile
- Departamento de Endocrinología, Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
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20
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Vaccinia Virus Encodes a Novel Inhibitor of Apoptosis That Associates with the Apoptosome. J Virol 2017; 91:JVI.01385-17. [PMID: 28904196 DOI: 10.1128/jvi.01385-17] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2017] [Accepted: 09/08/2017] [Indexed: 12/29/2022] Open
Abstract
Apoptosis is an important antiviral host defense mechanism. Here we report the identification of a novel apoptosis inhibitor encoded by the vaccinia virus (VACV) M1L gene. M1L is absent in the attenuated modified vaccinia virus Ankara (MVA) strain of VACV, a strain that stimulates apoptosis in several types of immune cells. M1 expression increased the viability of MVA-infected THP-1 and Jurkat cells and reduced several biochemical hallmarks of apoptosis, such as PARP-1 and procaspase-3 cleavage. Furthermore, ectopic M1L expression decreased staurosporine-induced (intrinsic) apoptosis in HeLa cells. We then identified the molecular basis for M1 inhibitory function. M1 allowed mitochondrial depolarization but blocked procaspase-9 processing, suggesting that M1 targeted the apoptosome. In support of this model, we found that M1 promoted survival in Saccharomyces cerevisiae overexpressing human Apaf-1 and procaspase-9, critical components of the apoptosome, or overexpressing only conformationally active caspase-9. In mammalian cells, M1 coimmunoprecipitated with Apaf-1-procaspase-9 complexes. The current model is that M1 associates with and allows the formation of the apoptosome but prevents apoptotic functions of the apoptosome. The M1 protein features 14 predicted ankyrin (ANK) repeat domains, and M1 is the first ANK-containing protein reported to use this inhibitory strategy. Since ANK-containing proteins are encoded by many large DNA viruses and found in all domains of life, studies of M1 may lead to a better understanding of the roles of ANK proteins in virus-host interactions.IMPORTANCE Apoptosis selectively eliminates dangerous cells such as virus-infected cells. Poxviruses express apoptosis antagonists to neutralize this antiviral host defense. The vaccinia virus (VACV) M1 ankyrin (ANK) protein, a protein with no previously ascribed function, inhibits apoptosis. M1 interacts with the apoptosome and prevents procaspase-9 processing as well as downstream procaspase-3 cleavage in several cell types and under multiple conditions. M1 is the first poxviral protein reported to associate with and prevent the function of the apoptosome, giving a more detailed picture of the threats VACV encounters during infection. Dysregulation of apoptosis is associated with several human diseases. One potential treatment of apoptosis-related diseases is through the use of designed ANK repeat proteins (DARPins), similar to M1, as caspase inhibitors. Thus, the study of the novel antiapoptosis effects of M1 via apoptosome association will be helpful for understanding how to control apoptosis using either natural or synthetic molecules.
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Lin M, Bachman K, Cheng Z, Daugherty SC, Nagaraj S, Sengamalay N, Ott S, Godinez A, Tallon LJ, Sadzewicz L, Fraser C, Dunning Hotopp JC, Rikihisa Y. Analysis of complete genome sequence and major surface antigens of Neorickettsia helminthoeca, causative agent of salmon poisoning disease. Microb Biotechnol 2017; 10:933-957. [PMID: 28585301 PMCID: PMC5481527 DOI: 10.1111/1751-7915.12731] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Revised: 03/09/2017] [Accepted: 04/25/2017] [Indexed: 12/31/2022] Open
Abstract
Neorickettsia helminthoeca, a type species of the genus Neorickettsia, is an endosymbiont of digenetic trematodes of veterinary importance. Upon ingestion of salmonid fish parasitized with infected trematodes, canids develop salmon poisoning disease (SPD), an acute febrile illness that is particularly severe and often fatal in dogs without adequate treatment. We determined and analysed the complete genome sequence of N. helminthoeca: a single small circular chromosome of 884 232 bp encoding 774 potential proteins. N. helminthoeca is unable to synthesize lipopolysaccharides and most amino acids, but is capable of synthesizing vitamins, cofactors, nucleotides and bacterioferritin. N. helminthoeca is, however, distinct from majority of the family Anaplasmataceae to which it belongs, as it encodes nearly all enzymes required for peptidoglycan biosynthesis, suggesting its structural hardiness and inflammatory potential. Using sera from dogs that were experimentally infected by feeding with parasitized fish or naturally infected in southern California, Western blot analysis revealed that among five predicted N. helminthoeca outer membrane proteins, P51 and strain‐variable surface antigen were uniformly recognized. Our finding will help understanding pathogenesis, prevalence of N. helminthoeca infection among trematodes, canids and potentially other animals in nature to develop effective SPD diagnostic and preventive measures. Recent progresses in large‐scale genome sequencing have been uncovering broad distribution of Neorickettsia spp., the comparative genomics will facilitate understanding of biology and the natural history of these elusive environmental bacteria.
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Affiliation(s)
- Mingqun Lin
- Department of Veterinary Biosciences, The Ohio State University, 1925 Coffey Road, Columbus, OH, 43210, USA
| | - Katherine Bachman
- Department of Veterinary Biosciences, The Ohio State University, 1925 Coffey Road, Columbus, OH, 43210, USA
| | - Zhihui Cheng
- Department of Veterinary Biosciences, The Ohio State University, 1925 Coffey Road, Columbus, OH, 43210, USA
| | - Sean C Daugherty
- Institute for Genome Sciences, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD, 21201, USA
| | - Sushma Nagaraj
- Institute for Genome Sciences, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD, 21201, USA
| | - Naomi Sengamalay
- Institute for Genome Sciences, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD, 21201, USA
| | - Sandra Ott
- Institute for Genome Sciences, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD, 21201, USA
| | - Al Godinez
- Institute for Genome Sciences, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD, 21201, USA
| | - Luke J Tallon
- Institute for Genome Sciences, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD, 21201, USA
| | - Lisa Sadzewicz
- Institute for Genome Sciences, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD, 21201, USA
| | - Claire Fraser
- Institute for Genome Sciences, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD, 21201, USA.,Department of Medicine, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD, 21201, USA
| | - Julie C Dunning Hotopp
- Institute for Genome Sciences, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD, 21201, USA.,Department of Microbiology and Immunology, University of Maryland School of Medicine, 801 W. Baltimore St, Baltimore, MD, 21201, USA
| | - Yasuko Rikihisa
- Department of Veterinary Biosciences, The Ohio State University, 1925 Coffey Road, Columbus, OH, 43210, USA
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Ehrlichia chaffeensis TRP32 is a Nucleomodulin that Directly Regulates Expression of Host Genes Governing Differentiation and Proliferation. Infect Immun 2016; 84:3182-3194. [PMID: 27572329 DOI: 10.1128/iai.00657-16] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Ehrlichia chaffeensis is an obligately intracellular bacterium that reprograms the mononuclear phagocyte through diverse effector-host interactions to modulate numerous host cell processes, including transcription. In a previous study, we reported that E. chaffeensis TRP32, a type 1 secreted effector, interacts with multiple host nucleus-associated proteins and also auto-activates reporter gene expression in yeast. In this study, we demonstrate that TRP32 is a nucleomodulin that binds host DNA and alters host gene transcription. TRP32 enters the host cell nucleus via a noncanonical translocation mechanism that involves phosphorylation of Y179 located in a C-terminal tri-tyrosine motif. Both genistein and mutation of Y179 inhibited TRP32 nuclear entry. An electromobility shift assay (EMSA) demonstrated TRP32 host DNA binding via its tandem repeat domain. TRP32 DNA binding and motif preference were further confirmed by supershift assays, as well as competition and mutant probe analyses. Using ChIP-Seq, we determined that TRP32 binds a G-rich motif primarily within ±500 bp of the gene transcription start site. An ontology analysis identified genes involved in processes such as immune cell differentiation, chromatin remodeling, and RNA transcription and processing, as primary TRP32 targets. TRP32 bound genes (n=1223) were distributed on all chromosomes and included several global regulators of proliferation and inflammation such as FOS and JUN, AKT3 and NRAS, and non-coding RNA genes, miRNA 21 and miRNA 142. TRP32 target genes were differentially regulated during infection, the majority of which were repressed, and direct repression/activation of these genes by TRP32 was confirmed in vitro with a cellular luciferase reporter assay.
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Ote M, Ueyama M, Yamamoto D. Wolbachia Protein TomO Targets nanos mRNA and Restores Germ Stem Cells in Drosophila Sex-lethal Mutants. Curr Biol 2016; 26:2223-32. [PMID: 27498563 DOI: 10.1016/j.cub.2016.06.054] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Revised: 05/16/2016] [Accepted: 06/22/2016] [Indexed: 11/27/2022]
Abstract
Wolbachia, endosymbiotic bacteria prevalent in invertebrates, manipulate their hosts in a variety of ways: they induce cytoplasmic incompatibility, male lethality, male-to-female transformation, and parthenogenesis. However, little is known about the molecular basis for host manipulation by these bacteria. In Drosophila melanogaster, Wolbachia infection makes otherwise sterile Sex-lethal (Sxl) mutant females capable of producing mature eggs. Through a functional genomic screen for Wolbachia genes with growth-inhibitory effects when expressed in cultured Drosophila cells, we identified the gene WD1278 encoding a novel protein we call toxic manipulator of oogenesis (TomO), which phenocopies some of the Wolbachia effects in Sxl mutant D. melanogaster females. We demonstrate that TomO enhances the maintenance of germ stem cells (GSCs) by elevating Nanos (Nos) expression via its interaction with nos mRNA, ultimately leading to the restoration of germ cell production in Sxl mutant females that are otherwise without GSCs.
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Affiliation(s)
- Manabu Ote
- Department of Developmental Biology and Neurosciences, Tohoku University Graduate School of Life Sciences, Sendai 980-8577, Japan
| | - Morio Ueyama
- Graduate School of Medicine, Osaka University, Suita 565-0871, Japan
| | - Daisuke Yamamoto
- Department of Developmental Biology and Neurosciences, Tohoku University Graduate School of Life Sciences, Sendai 980-8577, Japan.
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25
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Hanson BR, Tan M. Intra-ChIP: studying gene regulation in an intracellular pathogen. Curr Genet 2016; 62:547-51. [PMID: 26886234 PMCID: PMC5139683 DOI: 10.1007/s00294-016-0580-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Accepted: 02/11/2016] [Indexed: 12/25/2022]
Abstract
Intracellular bacteria that reside within a host cell use a variety of strategies to exploit this unique niche. While these organisms are technically challenging to study in the context of an infected host cell, recent advances have led to an improved understanding of how the intracellular environment impacts bacterial gene expression. We recently demonstrated that chromatin immunoprecipitation (ChIP) can be used to quantify transcription factor binding in the obligate intracellular pathogen Chlamydia trachomatis within infected cells. Furthermore, we showed it was possible to experimentally modulate transcription factor binding while simultaneously measuring changes in transcription. Here we discuss these findings as well as other recent work that has used ChIP to study intracellular pathogens within infected cells. We also discuss technical considerations associated with this approach and its possible future applications.
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Affiliation(s)
- Brett R Hanson
- Department of Microbiology and Molecular Genetics, University of California, B240 Med Sci, Irvine, CA, 92697-4025, USA
| | - Ming Tan
- Department of Microbiology and Molecular Genetics, University of California, B240 Med Sci, Irvine, CA, 92697-4025, USA.
- Department of Medicine, University of California, Irvine, CA, USA.
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26
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Agrawal AK, Ranjan R, Chandra S, Rout TK, Misra A, Reddy TJ. Some proteins of M. tuberculosis that localise to the nucleus of THP-1-derived macrophages. Tuberculosis (Edinb) 2016; 101:75-78. [PMID: 27865402 DOI: 10.1016/j.tube.2016.07.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Revised: 07/20/2016] [Accepted: 07/21/2016] [Indexed: 01/21/2023]
Abstract
Host-pathogen dialectics in tuberculosis (TB) via DNA-protein interactions are emerging. We investigated whether proteins produced by Mycobacterium tuberculosis (Mtb) could translocate to the host nucleus. Using lysates of nuclei purified from Mtb-infected THP-1-derived macrophages, we identified at least 15 proteins of Mtb-origin by electrophoretic and chromatographic separation and mass spectrometry. Western blotting confirmed time-dependent accumulation of Mtb EF-Tu, GroEL, GroES and MtrA in the host nucleus. MtrA could pull down at least 16 host proteins. Mtb proteins may have moonlighting functions that affect host gene expression.
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Affiliation(s)
| | - Rajeev Ranjan
- CSIR Central Drug Research Institute, Lucknow 226031, India
| | - Sharat Chandra
- CSIR Central Drug Research Institute, Lucknow 226031, India
| | | | - Amit Misra
- CSIR Central Drug Research Institute, Lucknow 226031, India.
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Abstract
Ehrlichia chaffeensis is an obligatory intracellular and cholesterol-dependent bacterium that has evolved special proteins and functions to proliferate inside leukocytes and cause disease. E. chaffeensis has a multigene family of major outer membrane proteins with porin activity and induces infectious entry using its entry-triggering protein to bind the human cell surface protein DNase X. During intracellular replication, three functional pairs of two-component systems are sequentially expressed to regulate metabolism, aggregation, and the development of stress-resistance traits for transmission. A type IV secretion effector of E. chaffeensis blocks mitochondrion-mediated host cell apoptosis. Several type I secretion proteins are secreted at the Ehrlichia-host interface. E. chaffeensis strains induce strikingly variable inflammation in mice. The central role of MyD88, but not Toll-like receptors, suggests that Ehrlichia species have unique inflammatory molecules. A recent report about transient targeted mutagenesis and random transposon mutagenesis suggests that stable targeted knockouts may become feasible in Ehrlichia.
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Affiliation(s)
- Yasuko Rikihisa
- Department of Veterinary Biosciences, College of Veterinary Medicine, The Ohio State University, Columbus, Ohio 43210;
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Lina TT, Farris T, Luo T, Mitra S, Zhu B, McBride JW. Hacker within! Ehrlichia chaffeensis Effector Driven Phagocyte Reprogramming Strategy. Front Cell Infect Microbiol 2016; 6:58. [PMID: 27303657 PMCID: PMC4885862 DOI: 10.3389/fcimb.2016.00058] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2016] [Accepted: 05/17/2016] [Indexed: 01/02/2023] Open
Abstract
Ehrlichia chaffeensis is a small, gram negative, obligately intracellular bacterium that preferentially infects mononuclear phagocytes. It is the etiologic agent of human monocytotropic ehrlichiosis (HME), an emerging life-threatening tick-borne zoonosis. Mechanisms by which E. chaffeensis establishes intracellular infection, and avoids host defenses are not well understood, but involve functionally relevant host-pathogen interactions associated with tandem and ankyrin repeat effector proteins. In this review, we discuss the recent advances in our understanding of the molecular and cellular mechanisms that underlie Ehrlichia host cellular reprogramming strategies that enable intracellular survival.
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Affiliation(s)
- Taslima T Lina
- Department of Pathology, University of Texas Medical Branch Galveston, TX, USA
| | - Tierra Farris
- Department of Pathology, University of Texas Medical Branch Galveston, TX, USA
| | - Tian Luo
- Department of Pathology, University of Texas Medical Branch Galveston, TX, USA
| | - Shubhajit Mitra
- Department of Pathology, University of Texas Medical Branch Galveston, TX, USA
| | - Bing Zhu
- Department of Pathology, University of Texas Medical Branch Galveston, TX, USA
| | - Jere W McBride
- Department of Pathology, University of Texas Medical BranchGalveston, TX, USA; Department of Microbiology and Immunology, University of Texas Medical BranchGalveston, TX, USA; Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical BranchGalveston, TX, USA; Sealy Center for Vaccine Development, University of Texas Medical BranchGalveston, TX, USA; Institute for Human Infections and Immunity, University of Texas Medical BranchGalveston, TX, USA
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29
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Weber MM, Faris R, McLachlan J, Tellez A, Wright WU, Galvan G, Luo ZQ, Samuel JE. Modulation of the host transcriptome by Coxiella burnetii nuclear effector Cbu1314. Microbes Infect 2016; 18:336-45. [DOI: 10.1016/j.micinf.2016.01.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2015] [Revised: 11/15/2015] [Accepted: 01/20/2016] [Indexed: 10/22/2022]
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Habib S, El Andaloussi A, Hisham A, Ismail N. NK Cell-Mediated Regulation of Protective Memory Responses against Intracellular Ehrlichial Pathogens. PLoS One 2016; 11:e0153223. [PMID: 27092553 PMCID: PMC4836677 DOI: 10.1371/journal.pone.0153223] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Accepted: 03/25/2016] [Indexed: 11/18/2022] Open
Abstract
Ehrlichiae are gram-negative obligate intracellular bacteria that cause potentially fatal human monocytic ehrlichiosis. We previously showed that natural killer (NK) cells play a critical role in host defense against Ehrlichia during primary infection. However, the contribution of NK cells to the memory response against Ehrlichia remains elusive. Primary infection of C57BL/6 mice with Ehrlichia muris provides long-term protection against a second challenge with the highly virulent Ixodes ovatus Ehrlichia (IOE), which ordinarily causes fatal disease in naïve mice. Here, we show that the depletion of NK cells in E. muris-primed mice abrogates the protective memory response against IOE. Approximately, 80% of NK cell-depleted E. muris-primed mice succumbed to lethal IOE infection on days 8-10 after IOE infection, similar to naïve mice infected with the same dose of IOE. The lack of a recall response in NK cell-depleted mice correlated with an increased bacterial burden, extensive liver injury, decreased frequency of Ehrlichia-specific IFN-γ-producing memory CD4+ and CD8+ T-cells, and a low titer of Ehrlichia-specific antibodies. Intraperitoneal infection of mice with E. muris resulted in the production of IL-15, IL-12, and IFN-γ as well as an expansion of activated NKG2D+ NK cells. The adoptive transfer of purified E. muris-primed hepatic and splenic NK cells into Rag2-/-Il2rg-/- recipient mice provided protective immunity against challenge with E. muris. Together, these data suggest that E. muris-induced memory-like NK cells, which contribute to the protective, recall response against Ehrlichia.
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Affiliation(s)
- Samar Habib
- Department of Obstetrics and Gynecology, Medical College of Georgia, Augusta University, Augusta, Georgia, United States of America
| | - Abdeljabar El Andaloussi
- Department of Obstetrics and Gynecology, Medical College of Georgia, Augusta University, Augusta, Georgia, United States of America
| | - Ahmed Hisham
- Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Nahed Ismail
- Department of Pathology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- * E-mail:
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31
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Niller HH, Minarovits J. Patho-epigenetics of Infectious Diseases Caused by Intracellular Bacteria. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 879:107-130. [PMID: 26659266 DOI: 10.1007/978-3-319-24738-0_6] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
In multicellular eukaryotes including plants, animals and humans, epigenetic reprogramming may play a role in the pathogenesis of a wide variety of diseases. Recent studies revealed that in addition to viruses, pathogenic bacteria are also capable to dysregulate the epigenetic machinery of their target cells. In this chapter we focus on epigenetic alterations induced by bacteria infecting humans. Most of them are obligate or facultative intracellular bacteria that produce either bacterial toxins and surface proteins targeting the host cell membrane, or synthesise effector proteins entering the host cell nucleus. These bacterial products typically elicit histone modifications, i.e. alter the "histone code". Bacterial pathogens are capable to induce alterations of host cell DNA methylation patterns, too. Such changes in the host cell epigenotype and gene expression pattern may hinder the antibacterial immune response and create favourable conditions for bacterial colonization, growth, or spread. Epigenetic dysregulation mediated by bacterial products may also facilitate the production of inflammatory cytokines and other inflammatory mediators affecting the epigenotype of their target cells. Such indirect epigenetic changes as well as direct interference with the epigenetic machinery of the host cells may contribute to the initiation and progression of malignant tumors associated with distinct bacterial infections.
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Affiliation(s)
- Hans Helmut Niller
- Institute of Medical Microbiology and Hygiene, University of Regensburg, Regensburg, Germany
| | - Janos Minarovits
- Department of Oral Biology and Experimental Dental Research, Faculty of Dentistry, University of Szeged, Tisza Lajos krt. 64, H-6720, Szeged, Hungary.
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32
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Song T, Ma Z, Shen D, Li Q, Li W, Su L, Ye T, Zhang M, Wang Y, Dou D. An Oomycete CRN Effector Reprograms Expression of Plant HSP Genes by Targeting their Promoters. PLoS Pathog 2015; 11:e1005348. [PMID: 26714171 PMCID: PMC4695088 DOI: 10.1371/journal.ppat.1005348] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Accepted: 11/29/2015] [Indexed: 01/03/2023] Open
Abstract
Oomycete pathogens produce a large number of CRN effectors to manipulate plant immune responses and promote infection. However, their functional mechanisms are largely unknown. Here, we identified a Phytophthora sojae CRN effector PsCRN108 which contains a putative DNA-binding helix-hairpin-helix (HhH) motif and acts in the plant cell nucleus. Silencing of the PsCRN108 gene reduced P. sojae virulence to soybean, while expression of the gene in Nicotiana benthamiana and Arabidopsis thaliana enhanced plant susceptibility to P. capsici. Moreover, PsCRN108 could inhibit expression of HSP genes in A. thaliana, N. benthamiana and soybean. Both the HhH motif and nuclear localization signal of this effector were required for its contribution to virulence and its suppression of HSP gene expression. Furthermore, we found that PsCRN108 targeted HSP promoters in an HSE- and HhH motif-dependent manner. PsCRN108 could inhibit the association of the HSE with the plant heat shock transcription factor AtHsfA1a, which initializes HSP gene expression in response to stress. Therefore, our data support a role for PsCRN108 as a nucleomodulin in down-regulating the expression of plant defense-related genes by directly targeting specific plant promoters.
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Affiliation(s)
- Tianqiao Song
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, Jiangsu, China
| | - Zhenchuan Ma
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, Jiangsu, China
| | - Danyu Shen
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, Jiangsu, China
| | - Qi Li
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, Jiangsu, China
| | - Wanlin Li
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, Jiangsu, China
| | - Liming Su
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, Jiangsu, China
| | - Tingyue Ye
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, Jiangsu, China
| | - Meixiang Zhang
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, Jiangsu, China
| | - Yuanchao Wang
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, Jiangsu, China
| | - Daolong Dou
- Department of Plant Pathology, Nanjing Agricultural University, Nanjing, Jiangsu, China
- * E-mail:
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33
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Moumène A, Meyer DF. Ehrlichia's molecular tricks to manipulate their host cells. Microbes Infect 2015; 18:172-9. [PMID: 26617397 DOI: 10.1016/j.micinf.2015.11.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Revised: 10/09/2015] [Accepted: 11/04/2015] [Indexed: 01/27/2023]
Abstract
Ehrlichia is a large genus of obligate intracellular Gram-negative bacteria transmitted by ticks that cause several emerging infectious diseases in humans and are pathogenic on rodents, ruminants, and dogs. Ehrlichia spp. invade and replicate either in endothelial cells, white blood cells, or within midgut cells and salivary glands of their vector ticks. In this review, we discuss the insights that functional studies are providing on how this group of bacteria exploits their host by subverting host innate immunity and hijacking cellular processes.
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Affiliation(s)
- Amal Moumène
- CIRAD, UMR CMAEE, Site de Duclos, Prise d'eau, F-97170 Petit-Bourg, Guadeloupe, France; INRA, UMR1309 CMAEE, F-34398 Montpellier, France; Université des Antilles et de la Guyane, 97159 Pointe-à-Pitre Cedex, Guadeloupe, France
| | - Damien F Meyer
- CIRAD, UMR CMAEE, Site de Duclos, Prise d'eau, F-97170 Petit-Bourg, Guadeloupe, France; INRA, UMR1309 CMAEE, F-34398 Montpellier, France.
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34
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Could ehrlichial infection cause some of the changes associated with leukemia, myelodysplastic diseases and autoimmune disorders, and offer antibiotic treatment options? Med Hypotheses 2015; 85:891-3. [PMID: 26394545 DOI: 10.1016/j.mehy.2015.09.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Revised: 08/15/2015] [Accepted: 09/12/2015] [Indexed: 10/23/2022]
Abstract
We hypothesize that a large group of medical conditions of unknown etiology including leukemia, multiple myeloma, myelodysplastic and autoimmune disorders, may be associated with or caused by an obscure group of intracellular obligate parasitic bacteria named Ehrlichia/Anaplasma (EA). Ensconced in the stem cells of the bone marrow, EA may disrupt the normal development and function of many of the cells of immunity, manifesting itself as different syndromes. Recent studies of the activity of EA suggest direct effects on the immune system consistent with the manifestations of leukemia. We reference here three leukemia patients with direct or indirect evidence of EA infection. Moreover, EA have been shown to be most sensitive to rifamycins. Two moribund leukemia patients with levels of platelets and white cells incompatible with life were treated with therapeutic doses of Rifampin. Though they did not survive, their condition improved dramatically for a time, suggesting Rifampin provided some therapeutic benefit. We assert that these results warrant more extensive study.
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35
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VieBrock L, Evans SM, Beyer AR, Larson CL, Beare PA, Ge H, Singh S, Rodino KG, Heinzen RA, Richards AL, Carlyon JA. Orientia tsutsugamushi ankyrin repeat-containing protein family members are Type 1 secretion system substrates that traffic to the host cell endoplasmic reticulum. Front Cell Infect Microbiol 2015; 4:186. [PMID: 25692099 PMCID: PMC4315096 DOI: 10.3389/fcimb.2014.00186] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Accepted: 12/11/2014] [Indexed: 11/18/2022] Open
Abstract
Scrub typhus is an understudied, potentially fatal infection that threatens one billion persons in the Asia-Pacific region. How the causative obligate intracellular bacterium, Orientia tsutsugamushi, facilitates its intracellular survival and pathogenesis is poorly understood. Many intracellular bacterial pathogens utilize the Type 1 (T1SS) or Type 4 secretion system (T4SS) to translocate ankyrin repeat-containing proteins (Anks) that traffic to distinct subcellular locations and modulate host cell processes. The O. tsutsugamushi genome encodes one of the largest known bacterial Ank repertoires plus T1SS and T4SS components. Whether these potential virulence factors are expressed during infection, how the Anks are potentially secreted, and to where they localize in the host cell are not known. We determined that O. tsutsugamushi transcriptionally expresses 20 unique ank genes as well as genes for both T1SS and T4SS during infection of mammalian host cells. Examination of the Anks' C-termini revealed that the majority of them resemble T1SS substrates. Escherichia coli expressing a functional T1SS was able to secrete chimeric hemolysin proteins bearing the C-termini of 19 of 20 O. tsutsugamushi Anks in an HlyBD-dependent manner. Thus, O. tsutsugamushi Anks C-termini are T1SS-compatible. Conversely, Coxiella burnetii could not secrete heterologously expressed Anks in a T4SS-dependent manner. Analysis of the subcellular distribution patterns of 20 ectopically expressed Anks revealed that, while 6 remained cytosolic or trafficked to the nucleus, 14 localized to, and in some cases, altered the morphology of the endoplasmic reticulum. This study identifies O. tsutsugamushi Anks as T1SS substrates and indicates that many display a tropism for the host cell secretory pathway.
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Affiliation(s)
- Lauren VieBrock
- Department of Microbiology and Immunology, Virginia Commonwealth University School of Medicine Richmond, VA, USA
| | - Sean M Evans
- Department of Microbiology and Immunology, Virginia Commonwealth University School of Medicine Richmond, VA, USA
| | - Andrea R Beyer
- Department of Microbiology and Immunology, Virginia Commonwealth University School of Medicine Richmond, VA, USA
| | - Charles L Larson
- Coxiella Pathogenesis Section, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health Hamilton, MT, USA
| | - Paul A Beare
- Coxiella Pathogenesis Section, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health Hamilton, MT, USA
| | - Hong Ge
- Viral and Rickettsial Diseases Department, Naval Medical Research Center Silver Spring, MD, USA
| | - Smita Singh
- Department of Microbiology and Immunology, Virginia Commonwealth University School of Medicine Richmond, VA, USA
| | - Kyle G Rodino
- Department of Microbiology and Immunology, Virginia Commonwealth University School of Medicine Richmond, VA, USA
| | - Robert A Heinzen
- Coxiella Pathogenesis Section, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health Hamilton, MT, USA
| | - Allen L Richards
- Viral and Rickettsial Diseases Department, Naval Medical Research Center Silver Spring, MD, USA
| | - Jason A Carlyon
- Department of Microbiology and Immunology, Virginia Commonwealth University School of Medicine Richmond, VA, USA
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Jernigan KK, Bordenstein SR. Tandem-repeat protein domains across the tree of life. PeerJ 2015; 3:e732. [PMID: 25653910 PMCID: PMC4304861 DOI: 10.7717/peerj.732] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2014] [Accepted: 12/29/2014] [Indexed: 12/19/2022] Open
Abstract
Tandem-repeat protein domains, composed of repeated units of conserved stretches of 20–40 amino acids, are required for a wide array of biological functions. Despite their diverse and fundamental functions, there has been no comprehensive assessment of their taxonomic distribution, incidence, and associations with organismal lifestyle and phylogeny. In this study, we assess for the first time the abundance of armadillo (ARM) and tetratricopeptide (TPR) repeat domains across all three domains in the tree of life and compare the results to our previous analysis on ankyrin (ANK) repeat domains in this journal. All eukaryotes and a majority of the bacterial and archaeal genomes analyzed have a minimum of one TPR and ARM repeat. In eukaryotes, the fraction of ARM-containing proteins is approximately double that of TPR and ANK-containing proteins, whereas bacteria and archaea are enriched in TPR-containing proteins relative to ARM- and ANK-containing proteins. We show in bacteria that phylogenetic history, rather than lifestyle or pathogenicity, is a predictor of TPR repeat domain abundance, while neither phylogenetic history nor lifestyle predicts ARM repeat domain abundance. Surprisingly, pathogenic bacteria were not enriched in TPR-containing proteins, which have been associated within virulence factors in certain species. Taken together, this comparative analysis provides a newly appreciated view of the prevalence and diversity of multiple types of tandem-repeat protein domains across the tree of life. A central finding of this analysis is that tandem repeat domain-containing proteins are prevalent not just in eukaryotes, but also in bacterial and archaeal species.
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Affiliation(s)
- Kristin K Jernigan
- Department of Cell and Developmental Biology, Vanderbilt University , Nashville, TN , USA
| | - Seth R Bordenstein
- Department of Biological Sciences, Vanderbilt University , Nashville, TN , USA ; Department of Pathology, Microbiology, and Immunology, Vanderbilt University , Nashville, TN , USA
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37
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Beyer AR, Truchan HK, May LJ, Walker NJ, Borjesson DL, Carlyon JA. The Anaplasma phagocytophilum effector AmpA hijacks host cell SUMOylation. Cell Microbiol 2014; 17:504-19. [PMID: 25308709 DOI: 10.1111/cmi.12380] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2014] [Revised: 09/18/2014] [Accepted: 10/03/2014] [Indexed: 12/25/2022]
Abstract
SUMOylation, the covalent attachment of a member of the small ubiquitin-like modifier (SUMO) family of proteins to lysines in target substrates, is an essential post-translational modification in eukaryotes. Microbial manipulation of SUMOylation recently emerged as a key virulence strategy for viruses and facultative intracellular bacteria, the latter of which have only been shown to deploy effectors that negatively regulate SUMOylation. Here, we demonstrate that the obligate intracellular bacterium, Anaplasma phagocytophilum, utilizes an effector, AmpA (A. phagocytophilum post-translationally modified protein A) that becomes SUMOylated in host cells and this is important for the pathogen's survival. We previously discovered that AmpA (formerly APH1387) localizes to the A. phagocytophilum-occupied vacuolar membrane (AVM). Algorithmic prediction analyses denoted AmpA as a candidate for SUMOylation. We verified this phenomenon using a SUMO affinity matrix to precipitate both native AmpA and ectopically expressed green fluorescent protein (GFP)-tagged AmpA. SUMOylation of AmpA was lysine dependent, as SUMO affinity beads failed to precipitate a GFP-AmpA protein when its lysine residues were substituted with arginine. Ectopically expressed and endogenous AmpA were poly-SUMOylated, which was consistent with the observation that AmpA colocalizes with SUMO2/3 at the AVM. Only late during the infection cycle did AmpA colocalize with SUMO1, which terminally caps poly-SUMO2/3 chains. AmpA was also detected in the cytosol of infected host cells, further supporting its secretion and likely participation in interactions that aid pathogen survival. Indeed, whereas siRNA-mediated knockdown of Ubc9 - a necessary enzyme for SUMOylation - slightly bolstered A. phagocytophilum infection, pharmacologically inhibiting SUMOylation in infected cells significantly reduced the bacterial load. Ectopically expressed GFP-AmpA served as a competitive agonist against native AmpA in infected cells, while lysine-deficient GFP-AmpA was less effective, implying that modification of AmpA lysines is important for infection. Collectively, these data show that AmpA becomes directly SUMOylated during infection, representing a novel tactic for A. phagocytophilum survival.
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Affiliation(s)
- Andrea R Beyer
- Department of Microbiology and Immunology, Virginia Commonwealth University School of Medicine, Richmond, VA, 23298, USA
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38
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Min CK, Kwon YJ, Ha NY, Cho BA, Kim JM, Kwon EK, Kim YS, Choi MS, Kim IS, Cho NH. Multiple Orientia tsutsugamushi ankyrin repeat proteins interact with SCF1 ubiquitin ligase complex and eukaryotic elongation factor 1 α. PLoS One 2014; 9:e105652. [PMID: 25166298 PMCID: PMC4148323 DOI: 10.1371/journal.pone.0105652] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2014] [Accepted: 07/22/2014] [Indexed: 11/30/2022] Open
Abstract
Background Orientia tsutsugamushi, the causative agent of scrub typhus, is an obligate intracellular bacterium. Previously, a large number of genes that encode proteins containing eukaryotic protein-protein interaction motifs such as ankyrin-repeat (Ank) domains were identified in the O. tsutsugamushi genome. However, little is known about the Ank protein function in O. tsutsugamushi. Methodology/Principal Findings To characterize the function of Ank proteins, we investigated a group of Ank proteins containing an F-box–like domain in the C-terminus in addition to the Ank domains. All nine selected ank genes were expressed at the transcriptional level in host cells infected with O. tsutsugamushi, and specific antibody responses against three Ank proteins were detected in the serum from human patients, indicating an active expression of the bacterial Ank proteins post infection. When ectopically expressed in HeLa cells, the Ank proteins of O. tsutsugamushi were consistently found in the nucleus and/or cytoplasm. In GST pull-down assays, multiple Ank proteins specifically interacted with Cullin1 and Skp1, core components of the SCF1 ubiquitin ligase complex, as well as the eukaryotic elongation factor 1 α (EF1α). Moreover, one Ank protein co-localized with the identified host targets and induced downregulation of EF1α potentially via enhanced ubiquitination. The downregulation of EF1α was observed consistently in diverse host cell types infected with O. tsutsugamushi. Conclusion/Significance These results suggest that conserved targeting and subsequent degradation of EF1α by multiple O. tsutsugamushi Ank proteins could be a novel bacterial strategy for replication and/or pathogenesis during mammalian host infection.
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Affiliation(s)
- Chan-Ki Min
- Department of Microbiology and Immunology, Seoul National University College of Medicine, Seoul, Republic of Korea
- Department of Biomedical Science, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Ye-Jin Kwon
- Department of Microbiology and Immunology, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Na-Young Ha
- Department of Microbiology and Immunology, Seoul National University College of Medicine, Seoul, Republic of Korea
- Department of Biomedical Science, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Bon-A Cho
- Department of Microbiology and Immunology, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Jo-Min Kim
- Department of Microbiology and Immunology, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Eun-Kyung Kwon
- Department of Microbiology and Immunology, Seoul National University College of Medicine, Seoul, Republic of Korea
- Department of Biomedical Science, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Yeon-Sook Kim
- Divisions of Infectious Diseases, Chungnam National University Hospital, Daejeon, Republic of Korea
| | - Myung-Sik Choi
- Department of Microbiology and Immunology, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Ik-Sang Kim
- Department of Microbiology and Immunology, Seoul National University College of Medicine, Seoul, Republic of Korea
| | - Nam-Hyuk Cho
- Department of Microbiology and Immunology, Seoul National University College of Medicine, Seoul, Republic of Korea
- Department of Biomedical Science, Seoul National University College of Medicine, Seoul, Republic of Korea
- Institute of Endemic Disease, Seoul National University Medical Research Center and Bundang Hospital, Seoul, Republic of Korea
- * E-mail:
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Takahashi K. Influence of bacteria on epigenetic gene control. Cell Mol Life Sci 2014; 71:1045-54. [PMID: 24132510 PMCID: PMC11113846 DOI: 10.1007/s00018-013-1487-x] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2013] [Revised: 09/25/2013] [Accepted: 09/26/2013] [Indexed: 01/26/2023]
Abstract
Cellular information is inherited by daughter cells through epigenetic routes in addition to genetic routes. Epigenetics, which is primarily mediated by inheritable DNA methylation and histone post-translational modifications, involves changes in the chromatin structure important for regulating gene expression. It is widely known that epigenetic control of gene expression plays an essential role in cell differentiation processes in vertebrates. Furthermore, because epigenetic changes can occur reversibly depending on environmental factors in differentiated cells, they have recently attracted considerable attention as targets for disease prevention and treatment. These environmental factors include diet, exposure to bacteria or viruses, and air pollution, of which this review focuses on the influence of bacteria on epigenetic gene control in a host. Host-bacterial interactions not only occur upon pathogenic bacterial infection but also continuously exist between commensal bacteria and the host. These bacterial stimuli play an essential role in various biological responses involving external stimuli and in maintaining physiological homeostasis by altering epigenetic markers and machinery.
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Affiliation(s)
- Kyoko Takahashi
- Food and Physiological Functions Laboratory, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa-shi, Kanagawa, 252-0880, Japan,
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Jernigan KK, Bordenstein SR. Ankyrin domains across the Tree of Life. PeerJ 2014; 2:e264. [PMID: 24688847 PMCID: PMC3932732 DOI: 10.7717/peerj.264] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2013] [Accepted: 01/15/2014] [Indexed: 11/20/2022] Open
Abstract
Ankyrin (ANK) repeats are one of the most common amino acid sequence motifs that mediate interactions between proteins of myriad sizes, shapes and functions. We assess their widespread abundance in Bacteria and Archaea for the first time and demonstrate in Bacteria that lifestyle, rather than phylogenetic history, is a predictor of ANK repeat abundance. Unrelated organisms that forge facultative and obligate symbioses with eukaryotes show enrichment for ANK repeats in comparison to free-living bacteria. The reduced genomes of obligate intracellular bacteria remarkably contain a higher fraction of ANK repeat proteins than other lifestyles, and the number of ANK repeats in each protein is augmented in comparison to other bacteria. Taken together, these results reevaluate the concept that ANK repeats are signature features of eukaryotic proteins and support the hypothesis that intracellular bacteria broadly employ ANK repeats for structure-function relationships with the eukaryotic host cell.
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Affiliation(s)
- Kristin K Jernigan
- Department of Biological Sciences, Vanderbilt University , Nashville , Tennessee , United States of America
| | - Seth R Bordenstein
- Department of Biological Sciences, Vanderbilt University , Nashville , Tennessee , United States of America ; Department of Pathology, Microbiology, and Immunology, Vanderbilt University , Nashville , Tennessee , United States of America
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Dunphy PS, Luo T, McBride JW. Ehrlichia moonlighting effectors and interkingdom interactions with the mononuclear phagocyte. Microbes Infect 2013; 15:1005-16. [PMID: 24141087 PMCID: PMC3886233 DOI: 10.1016/j.micinf.2013.09.011] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2013] [Revised: 09/27/2013] [Accepted: 09/30/2013] [Indexed: 01/19/2023]
Abstract
Ehrlichia chaffeensis is an obligately intracellular gram negative bacterium with a small genome that thrives in mammalian mononuclear phagocytes by exploiting eukaryotic processes. Herein, we discuss the latest findings on moonlighting tandem repeat protein effectors and their secretion mechanisms, and novel molecular interkingdom interactions that provide insight into the intracellular pathobiology of ehrlichiae.
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Affiliation(s)
- Paige Selvy Dunphy
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas 77555
| | - Tian Luo
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas 77555
| | - Jere W. McBride
- Department of Pathology, University of Texas Medical Branch, Galveston, Texas 77555
- Department of Microbiology and Immunology, University of Texas Medical Branch, Galveston, Texas 77555
- Center for Biodefense and Emerging Infectious Diseases, University of Texas Medical Branch, Galveston, Texas 77555
- Sealy Center for Vaccine Development, University of Texas Medical Branch, Galveston, Texas 77555
- Institute for Human Infections and Immunity, University of Texas Medical Branch, Galveston, Texas 77555
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The α-proteobacteria Wolbachia pipientis protein disulfide machinery has a regulatory mechanism absent in γ-proteobacteria. PLoS One 2013; 8:e81440. [PMID: 24282596 PMCID: PMC3839904 DOI: 10.1371/journal.pone.0081440] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Accepted: 10/21/2013] [Indexed: 11/19/2022] Open
Abstract
The α-proteobacterium Wolbachia pipientis infects more than 65% of insect species worldwide and manipulates the host reproductive machinery to enable its own survival. It can live in mutualistic relationships with hosts that cause human disease, including mosquitoes that carry the Dengue virus. Like many other bacteria, Wolbachia contains disulfide bond forming (Dsb) proteins that introduce disulfide bonds into secreted effector proteins. The genome of the Wolbachia strain wMel encodes two DsbA-like proteins sharing just 21% sequence identity to each other, α-DsbA1 and α-DsbA2, and an integral membrane protein, α-DsbB. α-DsbA1 and α-DsbA2 both have a Cys-X-X-Cys active site that, by analogy with Escherichia coli DsbA, would need to be oxidized to the disulfide form to serve as a disulfide bond donor toward substrate proteins. Here we show that the integral membrane protein α-DsbB oxidizes α-DsbA1, but not α-DsbA2. The interaction between α-DsbA1 and α-DsbB is very specific, involving four essential cysteines located in the two periplasmic loops of α-DsbB. In the electron flow cascade, oxidation of α-DsbA1 by α-DsbB is initiated by an oxidizing quinone cofactor that interacts with the cysteine pair in the first periplasmic loop. Oxidizing power is transferred to the second cysteine pair, which directly interacts with α-DsbA1. This reaction is inhibited by a non-catalytic disulfide present in α-DsbA1, conserved in other α-proteobacterial DsbAs but not in γ-proteobacterial DsbAs. This is the first characterization of the integral membrane protein α-DsbB from Wolbachia and reveals that the non-catalytic cysteines of α-DsbA1 regulate the redox relay system in cooperation with α-DsbB.
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Identification of Coxiella burnetii type IV secretion substrates required for intracellular replication and Coxiella-containing vacuole formation. J Bacteriol 2013; 195:3914-24. [PMID: 23813730 DOI: 10.1128/jb.00071-13] [Citation(s) in RCA: 86] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Coxiella burnetii, the etiological agent of acute and chronic Q fever in humans, is a naturally intracellular pathogen that directs the formation of an acidic Coxiella-containing vacuole (CCV) derived from the host lysosomal network. Central to its pathogenesis is a specialized type IVB secretion system (T4SS) that delivers effectors essential for intracellular replication and CCV formation. Using a bioinformatics-guided approach, 234 T4SS candidate substrates were identified. Expression of each candidate as a TEM-1 β-lactamase fusion protein led to the identification of 53 substrates that were translocated in a Dot/Icm-dependent manner. Ectopic expression in HeLa cells revealed that these substrates trafficked to distinct subcellular sites, including the endoplasmic reticulum, mitochondrion, and nucleus. Expression in Saccharomyces cerevisiae identified several substrates that were capable of interfering with yeast growth, suggesting that these substrates target crucial host processes. To determine if any of these T4SS substrates are necessary for intracellular replication, we isolated 20 clonal T4SS substrate mutants using the Himar1 transposon and transposase. Among these, 10 mutants exhibited defects in intracellular growth and CCV formation in HeLa and J774A.1 cells but displayed normal growth in bacteriological medium. Collectively, these results indicate that C. burnetii encodes a large repertoire of T4SS substrates that play integral roles in host cell subversion and CCV formation and suggest less redundancy in effector function than has been found in the comparative Legionella Dot/Icm model.
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Rennoll-Bankert KE, Dumler JS. Lessons from Anaplasma phagocytophilum: chromatin remodeling by bacterial effectors. Infect Disord Drug Targets 2013; 12:380-7. [PMID: 23082961 PMCID: PMC3664514 DOI: 10.2174/187152612804142242] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Revised: 08/27/2012] [Accepted: 08/27/2012] [Indexed: 02/06/2023]
Abstract
Bacterial pathogens can alter global host gene expression via histone modifications and chromatin remodeling in order to subvert host responses, including those involved with innate immunity, allowing for bacterial survival. Shigella flexneri, Listeria monocytogenes, Chlamydia trachomatis, and Anaplasma phagocytophilum express effector proteins that modify host histones and chromatin structure. A. phagocytophilum modulates granulocyte respiratory burst in part by dampening transcription of several key phagocyte oxidase genes. The A. phagocytophilum protein AnkA localizes to the myeloid cell nucleus where it binds AT-rich regions in the CYBB promoter and decreases its transcription. AT-rich regions of DNA are characteristic of matrix attachment regions (MARs) which are critical for chromatin structure and transcription. MAR-binding proteins, such as SATB1, interact with histone modifying enzymes resulting in altered gene expression. With A. phagocytophilum infection, histone deacetylase 1 (HDAC1) expression is increased and histone H3 acetylation is decreased at the CYBB promoter, suggesting a role for AnkA in altering host epigenetics and modulating gene transcription, at this, and perhaps other loci. This review will focus on how bacterial pathogens alter host epigenetics, by specifically examining A. phagocytophilum AnkA cis-regulation of CYBB transcription and epigenetic changes associated with infection.
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45
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Lei L, Dong X, Li Z, Zhong G. Identification of a novel nuclear localization signal sequence in Chlamydia trachomatis-secreted hypothetical protein CT311. PLoS One 2013; 8:e64529. [PMID: 23717625 PMCID: PMC3662721 DOI: 10.1371/journal.pone.0064529] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2013] [Accepted: 04/16/2013] [Indexed: 12/03/2022] Open
Abstract
We previously reported that Chlamydia trachomatis hypothetical protein CT311 was secreted out of chlamydial inclusion and into host cell cytosol. We now found that CT311 further entered host cell nucleus at the late stage of infection and continued to accumulate in the nucleus of C. trachomatis-infected cells. When CT311 was expressed via a transgene in mammalian cells, CT311 protein was exclusively detected in the nucleus, suggesting that CT311 by itself is sufficient for nuclear targeting. However, preexisting nuclear CT311 did not affect subsequent chlamydial infection. Using deletion constructs, we mapped a nuclear localization signal sequence of CT311 to residues 21 to 63 (21AVEGKPLSRAAQLRERRKDLHVSGKPSPRYALKKRALEAKKNK63). This sequence was sufficient for targeting a heterologous protein into mammalian cell nucleus and it contains two independent clusters of basic residues (34RERRK38 and 53KKRALEAKKNK63 respectively). Deletion or alanine substitution of the basic residues in either cluster led to loss of nuclear targeting activity, suggesting that both clusters are critical for the nuclear targeting function. These observations have demonstrated that the hypothetical protein CT311 possesses a novel nuclear localization signal sequence with dual modules of basic residues for targeting host cell nucleus during Chlamydia trachomatis infection.
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Affiliation(s)
- Lei Lei
- Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Xiaohua Dong
- Department of Pharmacology, School of Pharmacy, Hebei Northern University, Zhangjiakou, Hebei, P. R. China
| | - Zhongyu Li
- Department of Microbiology, University of South China, Hengyang, Hunan, P. R. China
| | - Guangming Zhong
- Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
- * E-mail:
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46
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Abstract
Immune response to pathogens depends on coordinated regulation of numerous genes that contribute collectively to pathogen elimination and restoration of the integrity of the affected tissue. The pathogen-induced gene expression is governed largely by the signal-induced posttranslational histone modifications that facilitate assembly of the functionally distinct chromatin complexes. In this review, we describe the principles of chromatin-based gene regulation during innate immune responses. We discuss the ability of pathogens to hijack the host response by interfering with various arms of transcriptional machinery involved in the responses. In particular, we discuss the phenomenon of the histone mimicry where interaction between histones and transcriptional regulators is targeted by pathogens that carry the histone-like sequences (histone mimics). We show how the principle of isotone mimicry as an efficient way to control host gene expression has been sued for the development of novel anti-inflammatory pharmacological approaches.
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47
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Abstract
Epigenetic mechanisms regulate expression of the genome to generate various cell types during development or orchestrate cellular responses to external stimuli. Recent studies highlight that bacteria can affect the chromatin structure and transcriptional program of host cells by influencing diverse epigenetic factors (i.e., histone modifications, DNA methylation, chromatin-associated complexes, noncoding RNAs, and RNA splicing factors). In this article, we first review the molecular bases of the epigenetic language and then describe the current state of research regarding how bacteria can alter epigenetic marks and machineries. Bacterial-induced epigenetic deregulations may affect host cell function either to promote host defense or to allow pathogen persistence. Thus, pathogenic bacteria can be considered as potential epimutagens able to reshape the epigenome. Their effects might generate specific, long-lasting imprints on host cells, leading to a memory of infection that influences immunity and might be at the origin of unexplained diseases.
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Affiliation(s)
- Hélène Bierne
- Institut Pasteur, Unité des Interactions Bactéries-Cellules, Paris F-75015, France.
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48
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Saha S, Hunter WB, Reese J, Morgan JK, Marutani-Hert M, Huang H, Lindeberg M. Survey of endosymbionts in the Diaphorina citri metagenome and assembly of a Wolbachia wDi draft genome. PLoS One 2012; 7:e50067. [PMID: 23166822 PMCID: PMC3500351 DOI: 10.1371/journal.pone.0050067] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Accepted: 10/17/2012] [Indexed: 02/03/2023] Open
Abstract
Diaphorina citri (Hemiptera: Psyllidae), the Asian citrus psyllid, is the insect vector of Ca. Liberibacter asiaticus, the causal agent of citrus greening disease. Sequencing of the D. citri metagenome has been initiated to gain better understanding of the biology of this organism and the potential roles of its bacterial endosymbionts. To corroborate candidate endosymbionts previously identified by rDNA amplification, raw reads from the D. citri metagenome sequence were mapped to reference genome sequences. Results of the read mapping provided the most support for Wolbachia and an enteric bacterium most similar to Salmonella. Wolbachia-derived reads were extracted using the complete genome sequences for four Wolbachia strains. Reads were assembled into a draft genome sequence, and the annotation assessed for the presence of features potentially involved in host interaction. Genome alignment with the complete sequences reveals membership of Wolbachia wDi in supergroup B, further supported by phylogenetic analysis of FtsZ. FtsZ and Wsp phylogenies additionally indicate that the Wolbachia strain in the Florida D. citri isolate falls into a sub-clade of supergroup B, distinct from Wolbachia present in Chinese D. citri isolates, supporting the hypothesis that the D. citri introduced into Florida did not originate from China.
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Affiliation(s)
- Surya Saha
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, New York, United States of America
| | - Wayne B. Hunter
- USDA-ARS, U.S. Horticultural Research Laboratory, Fort Pierce, Florida, United States of America
| | - Justin Reese
- Genformatic, LLC., Alpharetta, Georgia, United States of America
| | - J. Kent Morgan
- USDA-ARS, U.S. Horticultural Research Laboratory, Fort Pierce, Florida, United States of America
| | - Mizuri Marutani-Hert
- USDA-ARS, U.S. Horticultural Research Laboratory, Fort Pierce, Florida, United States of America
| | - Hong Huang
- School of Information, University of South Florida, Tampa, Florida, United States of America
| | - Magdalen Lindeberg
- Department of Plant Pathology and Plant-Microbe Biology, Cornell University, Ithaca, New York, United States of America
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TolC-dependent secretion of an ankyrin repeat-containing protein of Rickettsia typhi. J Bacteriol 2012; 194:4920-32. [PMID: 22773786 DOI: 10.1128/jb.00793-12] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Rickettsia typhi, the causative agent of murine (endemic) typhus, is an obligate intracellular pathogen with a life cycle involving both vertebrate and invertebrate hosts. In this study, we characterized a gene (RT0218) encoding a C-terminal ankyrin repeat domain-containing protein, named Rickettsia ankyrin repeat protein 1 (RARP-1), and identified it as a secreted effector protein of R. typhi. RT0218 showed differential transcript abundance at various phases of R. typhi intracellular growth. RARP-1 was secreted by R. typhi into the host cytoplasm during in vitro infection of mammalian cells. Transcriptional analysis revealed that RT0218 was cotranscribed with adjacent genes RT0217 (hypothetical protein) and RT0216 (TolC) as a single polycistronic mRNA. Given one of its functions as a facilitator of extracellular protein secretion in some Gram-negative bacterial pathogens, we tested the possible role of TolC in the secretion of RARP-1. Using Escherichia coli C600 and an isogenic tolC insertion mutant as surrogate hosts, our data demonstrate that RARP-1 is secreted in a TolC-dependent manner. Deletion of either the N-terminal signal peptide or the C-terminal ankyrin repeats abolished RARP-1 secretion by wild-type E. coli. Importantly, expression of R. typhi tolC in the E. coli tolC mutant restored the secretion of RARP-1, suggesting that TolC has a role in RARP-1 translocation across the outer membrane. This work implies that the TolC component of the putative type 1 secretion system of R. typhi is involved in the secretion process of RARP-1.
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Dedonder SE, Cheng C, Willard LH, Boyle DL, Ganta RR. Transmission electron microscopy reveals distinct macrophage- and tick cell-specific morphological stages of Ehrlichia chaffeensis. PLoS One 2012; 7:e36749. [PMID: 22615806 PMCID: PMC3352939 DOI: 10.1371/journal.pone.0036749] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Accepted: 04/11/2012] [Indexed: 11/18/2022] Open
Abstract
Background Ehrlichia chaffeensis is an emerging tick-borne rickettsial pathogen responsible for human monocytic ehrlichiosis. Despite the induction of an active host immune response, the pathogen has evolved to persist in its vertebrate and tick hosts. Understanding how the organism progresses in tick and vertebrate host cells is critical in identifying effective strategies to block the pathogen transmission. Our recent molecular and proteomic studies revealed differences in numerous expressed proteins of the organism during its growth in different host environments. Methodology/Principal Findings Transmission electron microscopy analysis was performed to assess morphological changes in the bacterium within macrophages and tick cells. The stages of pathogen progression observed included the attachment of the organism to the host cells, its engulfment and replication within a morulae by binary fission and release of the organisms from infected host cells by complete host cell lysis or by exocytosis. E. chaffeensis grown in tick cells was highly pleomorphic and appears to replicate by both binary fission and filamentous type cell divisions. The presence of Ehrlichia-like inclusions was also observed within the nucleus of both macrophages and tick cells. This observation was confirmed by confocal microscopy and immunoblot analysis. Conclusions/Significance Morphological differences in the pathogen’s progression, replication, and processing within macrophages and tick cells provide further evidence that E. chaffeensis employs unique host-cell specific strategies in support of adaptation to vertebrate and tick cell environments.
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Affiliation(s)
- Sarah E Dedonder
- Department of Diagnostic Medicine/Pathobiology, College of Veterinary Medicine, Kansas State University, Manhattan, Kansas, United States of America
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