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Zhao M, Zhang S, Wan W, Zhou C, Li N, Cheng R, Yu Y, Ouyang X, Zhou D, Jiao J, Xiong X. Coxiella burnetii effector CvpE maintains biogenesis of Coxiella-containing vacuoles by suppressing lysosome tubulation through binding PI(3)P and perturbing PIKfyve activity on lysosomes. Virulence 2024; 15:2350893. [PMID: 38725096 PMCID: PMC11085968 DOI: 10.1080/21505594.2024.2350893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2023] [Accepted: 04/27/2024] [Indexed: 05/12/2024] Open
Abstract
Coxiella burnetii (C. burnetii) is the causative agent of Q fever, a zoonotic disease. Intracellular replication of C. burnetii requires the maturation of a phagolysosome-like compartment known as the replication permissive Coxiella-containing vacuole (CCV). Effector proteins secreted by the Dot/Icm secretion system are indispensable for maturation of a single large CCV by facilitating the fusion of promiscuous vesicles. However, the mechanisms of CCV maintenance and evasion of host cell clearance remain to be defined. Here, we show that C. burnetii secreted Coxiella vacuolar protein E (CvpE) contributes to CCV biogenesis by inducing lysosome-like vacuole (LLV) enlargement. LLV fission by tubulation and autolysosome degradation is impaired in CvpE-expressing cells. Subsequently, we found that CvpE suppresses lysosomal Ca2+ channel transient receptor potential channel mucolipin 1 (TRPML1) activity in an indirect manner, in which CvpE binds phosphatidylinositol 3-phosphate [PI(3)P] and perturbs PIKfyve activity in lysosomes. Finally, the agonist of TRPML1, ML-SA5, inhibits CCV biogenesis and C. burnetii replication. These results provide insight into the mechanisms of CCV maintenance by CvpE and suggest that the agonist of TRPML1 can be a novel potential treatment that does not rely on antibiotics for Q fever by enhancing Coxiella-containing vacuoles (CCVs) fission.
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Affiliation(s)
- Mingliang Zhao
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Shan Zhang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Weiqiang Wan
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
- College of Life Sciences, Southwest Forestry University, Kunming, Yunnan, China
| | - Chunyu Zhou
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
- School of Public Health, Mudanjiang Medical University, Mudanjiang, Heilongjiang, China
| | - Nana Li
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
- School of Public Health, Anhui Medical University, Hefei, Anhui, China
| | - Ruxi Cheng
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Yonghui Yu
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Xuan Ouyang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Dongsheng Zhou
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Jun Jiao
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Xiaolu Xiong
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
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2
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Schulze-Luehrmann J, Liebler-Tenorio E, Felipe-López A, Lührmann A. Cell death induction facilitates egress of Coxiella burnetii from infected host cells at late stages of infection. Mol Microbiol 2024; 121:513-528. [PMID: 38115201 DOI: 10.1111/mmi.15210] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Revised: 11/22/2023] [Accepted: 11/27/2023] [Indexed: 12/21/2023]
Abstract
Intracellular bacteria have evolved mechanisms to invade host cells, establish an intracellular niche that allows survival and replication, produce progeny, and exit the host cell after completion of the replication cycle to infect new target cells. Bacteria exit their host cell by (i) initiation of apoptosis, (ii) lytic cell death, and (iii) exocytosis. While bacterial egress is essential for bacterial spreading and, thus, pathogenesis, we currently lack information about egress mechanisms for the obligate intracellular pathogen C. burnetii, the causative agent of the zoonosis Q fever. Here, we demonstrate that C. burnetii inhibits host cell apoptosis early during infection, but induces and/or increases apoptosis at later stages of infection. Only at later stages of infection did we observe C. burnetii egress, which depends on previously established large bacteria-filled vacuoles and a functional intrinsic apoptotic cascade. The released bacteria are not enclosed by a host cell membrane and can infect and replicate in new target cells. In summary, our data argue that C. burnetii egress in a non-synchronous way at late stages of infection. Apoptosis-induction is important for C. burnetii egress, but other pathways most likely contribute.
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Affiliation(s)
- Jan Schulze-Luehrmann
- Mikrobiologisches Institut, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | | | - Alfonso Felipe-López
- Mikrobiologisches Institut, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Anja Lührmann
- Mikrobiologisches Institut, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
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3
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Thomas DR, Garnish SE, Khoo CA, Padmanabhan B, Scott NE, Newton HJ. Coxiella burnetii protein CBU2016 supports CCV expansion. Pathog Dis 2024; 82:ftae018. [PMID: 39138067 DOI: 10.1093/femspd/ftae018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Revised: 07/28/2024] [Accepted: 08/13/2024] [Indexed: 08/15/2024] Open
Abstract
Coxiella burnetii is a globally distributed obligate intracellular pathogen. Although often asymptomatic, infections can cause acute Q fever with influenza-like symptoms and/or severe chronic Q fever. Coxiella burnetii develops a unique replicative niche within host cells called the Coxiella-containing vacuole (CCV), facilitated by the Dot/Icm type IV secretion system translocating a cohort of bacterial effector proteins into the host. The role of some effectors has been elucidated; however, the actions of the majority remain enigmatic and the list of true effectors is disputable. This study examined CBU2016, a unique C. burnetii protein previously designated as an effector with a role in infection. We were unable to validate CBU2016 as a translocated effector protein. Employing targeted knock-out and complemented strains, we found that the loss of CBU2016 did not cause a replication defect within Hela, THP-1, J774, or iBMDM cells or in axenic media, nor did it affect the pathogenicity of C. burnetii in the Galleria mellonella infection model. The absence of CBU2016 did, however, result in a consistent decrease in the size of CCVs in HeLa cells. These results suggest that although CBU2016 may not be a Dot/Icm effector, it is still able to influence the host environment during infection.
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Affiliation(s)
- David R Thomas
- Infection Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, VIC 3800, Australia
- Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, VIC 3000, Australia
| | - Sarah E Garnish
- Infection Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, VIC 3800, Australia
| | - Chen Ai Khoo
- Infection Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, VIC 3800, Australia
| | - Bhavna Padmanabhan
- Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, VIC 3000, Australia
| | - Nichollas E Scott
- Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, VIC 3000, Australia
| | - Hayley J Newton
- Infection Program, Monash Biomedicine Discovery Institute and Department of Microbiology, Monash University, Clayton, VIC 3800, Australia
- Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, VIC 3000, Australia
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Wan W, Zhang S, Zhao M, OuYang X, Yu Y, Xiong X, Zhao N, Jiao J. Lysosomal trafficking regulator restricts intracellular growth of Coxiella burnetii by inhibiting the expansion of Coxiella-containing vacuole and upregulating nos2 expression. Front Cell Infect Microbiol 2024; 13:1336600. [PMID: 38282619 PMCID: PMC10812120 DOI: 10.3389/fcimb.2023.1336600] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2023] [Accepted: 12/26/2023] [Indexed: 01/30/2024] Open
Abstract
Coxiella burnetii is an obligate intracellular bacterium that causes Q fever, a zoonotic disease typically manifests as a severe flu-illness. After invading into the host cells, C. burnetii delivers effectors to regulate the vesicle trafficking and fusion events to form a large and mature Coxiella-containing vacuole (CCV), providing sufficient space and nutrition for its intracellular growth and proliferation. Lysosomal trafficking regulator (LYST) is a member of the Beige and Chediak-Higashi syndrome (BEACH) family, which regulates the transport of vesicles to lysosomes and regulates TLR signaling pathway, but the effect of LYST on C. burnetii infection is unclear. In this study, a series of experiments has been conducted to investigate the influence of LYST on intracellular growth of C. burnetii. Our results showed that lyst transcription was up-regulated in the host cells after C. burnetii infection, but there is no significant change in lyst expression level after infection with the Dot/Icm type IV secretion system (T4SS) mutant strain, while CCVs expansion and significantly increasing load of C. burnetii appeared in the host cells with a silenced lyst gene, suggesting LYST inhibits the intracellular proliferation of C. burnetii by reducing CCVs size. Then, the size of CCVs and the load of C. burnetii in the HeLa cells pretreated with E-64d were significantly decreased. In addition, the level of iNOS was decreased significantly in LYST knockout THP-1 cells, which was conducive to the intracellular replication of C. burnetii. This data is consistent with the phenotype of L-NMMA-treated THP-1 cells infected with C. burnetii. Our results revealed that the upregulation of lyst transcription after infection is due to effector secretion of C. burnetii and LYST inhibit the intracellular replication of C. burnetii by reducing the size of CCVs and inducing nos2 expression.
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Affiliation(s)
- Weiqiang Wan
- College of Life Sciences, Southwest Forestry University, Kunming, China
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Shan Zhang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Mingliang Zhao
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Xuan OuYang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Yonghui Yu
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Xiaolu Xiong
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Ning Zhao
- College of Life Sciences, Southwest Forestry University, Kunming, China
| | - Jun Jiao
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
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5
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Höpfner D, Cichy A, Pogenberg V, Krisp C, Mezouar S, Bach NC, Grotheer J, Zarza SM, Martinez E, Bonazzi M, Feige MJ, Sieber SA, Schlüter H, Itzen A. The DNA-binding induced (de)AMPylation activity of a Coxiella burnetii Fic enzyme targets Histone H3. Commun Biol 2023; 6:1124. [PMID: 37932372 PMCID: PMC10628234 DOI: 10.1038/s42003-023-05494-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Accepted: 10/20/2023] [Indexed: 11/08/2023] Open
Abstract
The intracellular bacterial pathogen Coxiella burnetii evades the host response by secreting effector proteins that aid in establishing a replication-friendly niche. Bacterial filamentation induced by cyclic AMP (Fic) enzymes can act as effectors by covalently modifying target proteins with the posttranslational AMPylation by transferring adenosine monophosphate (AMP) from adenosine triphosphate (ATP) to a hydroxyl-containing side chain. Here we identify the gene product of C. burnetii CBU_0822, termed C. burnetii Fic 2 (CbFic2), to AMPylate host cell histone H3 at serine 10 and serine 28. We show that CbFic2 acts as a bifunctional enzyme, both capable of AMPylation as well as deAMPylation, and is regulated by the binding of DNA via a C-terminal helix-turn-helix domain. We propose that CbFic2 performs AMPylation in its monomeric state, switching to a deAMPylating dimer upon DNA binding. This study unveils reversible histone modification by a specific enzyme of a pathogenic bacterium.
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Affiliation(s)
- Dorothea Höpfner
- Institute of Biochemistry and Signal Transduction, University Medical Center Hamburg-Eppendorf (UKE), Martinistraße 52, 20246, Hamburg, Germany
| | - Adam Cichy
- Center for Integrated Protein Science Munich (CIPSM), Department Chemistry, Group of Proteinchemistry, Technical University of Munich, Lichtenbergstraße 4, 85747, Garching, Germany
| | - Vivian Pogenberg
- Institute of Biochemistry and Signal Transduction, University Medical Center Hamburg-Eppendorf (UKE), Martinistraße 52, 20246, Hamburg, Germany
| | - Christoph Krisp
- Institute of Clinical Chemistry and Laboratory Medicine, Section Mass Spectrometry and Proteomics, University Medical Center Hamburg-Eppendorf (UKE), Martinistraße 52, 20246, Hamburg, Germany
| | - Soraya Mezouar
- Aix-Marseille University, Institut de Recherche pour la Développement (IRD), Assistance Publique-Hôpitaux de Marseille (APHM), Microbes Evolution Phylogeny and Infections (MEPHI), Institut Hospitalo-Universitaire (IHU)-Méditerranée Infection, Boulevard Jean Moulin, 13005, Marseille, France
| | - Nina C Bach
- Technical University of Munich (TUM), TUM School of Natural Sciences, Department of Biosciences, Chair of Organic Chemistry II, Center for Functional Protein Assemblies (CPA), Ernst-Otto-Fischer Straße 8, 85748, Garching, Germany
| | - Jan Grotheer
- Institute of Biochemistry and Signal Transduction, University Medical Center Hamburg-Eppendorf (UKE), Martinistraße 52, 20246, Hamburg, Germany
| | - Sandra Madariaga Zarza
- Aix-Marseille University, Institut de Recherche pour la Développement (IRD), Assistance Publique-Hôpitaux de Marseille (APHM), Microbes Evolution Phylogeny and Infections (MEPHI), Institut Hospitalo-Universitaire (IHU)-Méditerranée Infection, Boulevard Jean Moulin, 13005, Marseille, France
| | - Eric Martinez
- Cellular and Molecular Biology of Bacterial Infections, Institut de Recherche en Infectiologie de Montpellier (IRIM), Université de Montpellier, UMR 9004 - Centre national de la recherche scientifique (CNRS), 1919 Route de Mende, 34293, Montpellier, France
| | - Matteo Bonazzi
- Cellular and Molecular Biology of Bacterial Infections, Institut de Recherche en Infectiologie de Montpellier (IRIM), Université de Montpellier, UMR 9004 - Centre national de la recherche scientifique (CNRS), 1919 Route de Mende, 34293, Montpellier, France
| | - Matthias J Feige
- Center for Functional Protein Assemblies (CPA), Department of Bioscience, TUM School of Natural Sciences, Technical University of Munich, Lichtenbergstraße 4, 85748, Garching, Germany
| | - Stephan A Sieber
- Technical University of Munich (TUM), TUM School of Natural Sciences, Department of Biosciences, Chair of Organic Chemistry II, Center for Functional Protein Assemblies (CPA), Ernst-Otto-Fischer Straße 8, 85748, Garching, Germany
| | - Hartmut Schlüter
- Institute of Clinical Chemistry and Laboratory Medicine, Section Mass Spectrometry and Proteomics, University Medical Center Hamburg-Eppendorf (UKE), Martinistraße 52, 20246, Hamburg, Germany
| | - Aymelt Itzen
- Institute of Biochemistry and Signal Transduction, University Medical Center Hamburg-Eppendorf (UKE), Martinistraße 52, 20246, Hamburg, Germany.
- Center for Structural Systems Biology (CSSB), University Medical Center Hamburg-Eppendorf (UKE), Martinistraße 52, 20246, Hamburg, Germany.
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6
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Wang T, Wang C, Li C, Song L. The intricate dance: host autophagy and Coxiella burnetii infection. Front Microbiol 2023; 14:1281303. [PMID: 37808314 PMCID: PMC10556474 DOI: 10.3389/fmicb.2023.1281303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Accepted: 09/11/2023] [Indexed: 10/10/2023] Open
Abstract
Q fever is a zoonotic disease caused by Coxiella burnetii, an obligatory intracellular bacterial pathogen. Like other intracellular pathogens, C. burnetii is able to survive and reproduce within host cells by manipulating host cellular processes. In particular, the relationship between C. burnetii infection and host autophagy, a cellular process involved in degradation and recycling, is of great interest due to its intricate nature. Studies have shown that autophagy can recognize and target intracellular pathogens such as Legionella and Salmonella for degradation, limiting their replication and promoting bacterial clearance. However, C. burnetii can actively manipulate the autophagic pathway to create an intracellular niche, known as the Coxiella-containing vacuole (CCV), where it can multiply and evade host immune responses. C. burnetii promotes the fusion of CCVs with lysosomes through mechanisms involving virulence factors such as Cig57 and CvpF. This review summarizes the latest findings on the dynamic interaction between host autophagy and C. burnetii infection, highlighting the complex strategies employed by both the bacterium and the host. A better understanding of these mechanisms could provide important insights into the development of novel therapeutic interventions and vaccine strategies against C. burnetii infections.
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Affiliation(s)
- Tingting Wang
- Department of Infectious Diseases, First Hospital of Zibo City, Zibo, China
| | - Chao Wang
- Department of Traditional Chinese Medicine, First Hospital of Zibo City, Zibo, China
| | - Chang Li
- Department of VIP Unit, China-Japan Union Hospital, Changchun, China
| | - Lei Song
- Department of Respiratory Medicine, Center for Pathogen Biology and Infectious Diseases, The First Hospital of Jilin University, Changchun, China
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Clemente TM, Angara RK, Gilk SD. Establishing the intracellular niche of obligate intracellular vacuolar pathogens. Front Cell Infect Microbiol 2023; 13:1206037. [PMID: 37645379 PMCID: PMC10461009 DOI: 10.3389/fcimb.2023.1206037] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Accepted: 07/21/2023] [Indexed: 08/31/2023] Open
Abstract
Obligate intracellular pathogens occupy one of two niches - free in the host cell cytoplasm or confined in a membrane-bound vacuole. Pathogens occupying membrane-bound vacuoles are sequestered from the innate immune system and have an extra layer of protection from antimicrobial drugs. However, this lifestyle presents several challenges. First, the bacteria must obtain membrane or membrane components to support vacuole expansion and provide space for the increasing bacteria numbers during the log phase of replication. Second, the vacuole microenvironment must be suitable for the unique metabolic needs of the pathogen. Third, as most obligate intracellular bacterial pathogens have undergone genomic reduction and are not capable of full metabolic independence, the bacteria must have mechanisms to obtain essential nutrients and resources from the host cell. Finally, because they are separated from the host cell by the vacuole membrane, the bacteria must possess mechanisms to manipulate the host cell, typically through a specialized secretion system which crosses the vacuole membrane. While there are common themes, each bacterial pathogen utilizes unique approach to establishing and maintaining their intracellular niches. In this review, we focus on the vacuole-bound intracellular niches of Anaplasma phagocytophilum, Ehrlichia chaffeensis, Chlamydia trachomatis, and Coxiella burnetii.
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Affiliation(s)
| | | | - Stacey D. Gilk
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE, United States
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Shepherd DC, Kaplan M, Vankadari N, Kim KW, Larson CL, Dutka P, Beare PA, Krzymowski E, Heinzen RA, Jensen GJ, Ghosal D. Morphological remodeling of Coxiella burnetii during its biphasic developmental cycle revealed by cryo-electron tomography. iScience 2023; 26:107210. [PMID: 37485371 PMCID: PMC10362272 DOI: 10.1016/j.isci.2023.107210] [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: 02/21/2023] [Revised: 05/05/2023] [Accepted: 06/21/2023] [Indexed: 07/25/2023] Open
Abstract
Coxiella burnetii is an obligate zoonotic bacterium that targets macrophages causing a disease called Q fever. It has a biphasic developmental life cycle where the extracellular and metabolically inactive small cell variant (SCV) transforms inside the host into the vegetative large cell variant (LCV). However, details about the morphological and structural changes of this transition are still lacking. Here, we used cryo-electron tomography to image both SCV and LCV variants grown either under axenic conditions or purified directly from host cells. We show that SCVs are characterized by equidistant stacks of inner membrane that presumably facilitate the transition to LCV, a transition coupled with the expression of the Dot/Icm type IVB secretion system (T4BSS). A class of T4BSS particles were associated with extracellular densities possibly involved in host infection. Also, SCVs contained spherical multilayered membrane structures of different sizes and locations suggesting no connection to sporulation as once assumed.
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Affiliation(s)
- Doulin C. Shepherd
- Department of Biochemistry and Pharmacology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, VIC, Australia
| | - Mohammed Kaplan
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
| | - Naveen Vankadari
- Department of Biochemistry and Pharmacology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, VIC, Australia
| | - Ki Woo Kim
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
- School of Ecology and Environmental System, Kyungpook National University, Sangju, Korea
| | - Charles L. Larson
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, USA
| | - Przemysław Dutka
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
- Division od Chemistry and Chemical Engineering, California Institute of Technology, 1200 California Boulevard, Pasadena, CA 91125, USA
| | - Paul A. Beare
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, USA
| | - Edward Krzymowski
- Department of Physics and Astronomy, Brigham Young University, Provo, UT 84604, USA
| | - Robert A. Heinzen
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, MT, USA
| | - Grant J. Jensen
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84604, USA
| | - Debnath Ghosal
- Department of Biochemistry and Pharmacology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, VIC, Australia
- ARC Centre for Cryo-electron Microscopy of Membrane Proteins, Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, VIC, Australia
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9
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Fisher DJ, Beare PA. Recent advances in genetic systems in obligate intracellular human-pathogenic bacteria. Front Cell Infect Microbiol 2023; 13:1202245. [PMID: 37404720 PMCID: PMC10315504 DOI: 10.3389/fcimb.2023.1202245] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Accepted: 05/22/2023] [Indexed: 07/06/2023] Open
Abstract
The ability to genetically manipulate a pathogen is fundamental to discovering factors governing host-pathogen interactions at the molecular level and is critical for devising treatment and prevention strategies. While the genetic "toolbox" for many important bacterial pathogens is extensive, approaches for modifying obligate intracellular bacterial pathogens were classically limited due in part to the uniqueness of their obligatory lifestyles. Many researchers have confronted these challenges over the past two and a half decades leading to the development of multiple approaches to construct plasmid-bearing recombinant strains and chromosomal gene inactivation and deletion mutants, along with gene-silencing methods enabling the study of essential genes. This review will highlight seminal genetic achievements and recent developments (past 5 years) for Anaplasma spp., Rickettsia spp., Chlamydia spp., and Coxiella burnetii including progress being made for the still intractable Orientia tsutsugamushi. Alongside commentary of the strengths and weaknesses of the various approaches, future research directions will be discussed to include methods for C. burnetii that should have utility in the other obligate intracellular bacteria. Collectively, the future appears bright for unraveling the molecular pathogenic mechanisms of these significant pathogens.
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Affiliation(s)
- Derek J. Fisher
- School of Biological Sciences, Southern Illinois University, Carbondale, IL, United States
| | - Paul A. Beare
- Rocky Mountain Laboratory, National Institute of Health, Hamilton, MT, United States
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10
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Larson CL, Pullman W, Beare PA, Heinzen RA. Identification of Type 4B Secretion System Substrates That Are Conserved among Coxiella burnetii Genomes and Promote Intracellular Growth. Microbiol Spectr 2023; 11:e0069623. [PMID: 37199620 PMCID: PMC10269450 DOI: 10.1128/spectrum.00696-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Accepted: 04/21/2023] [Indexed: 05/19/2023] Open
Abstract
Coxiella burnetii is a Gram-negative pathogen that infects a variety of mammalian hosts. Infection of domesticated ewes can cause fetal abortion, whereas acute human infection normally manifests as the flu-like illness Q fever. Successful host infection requires replication of the pathogen within the lysosomal Coxiella-containing vacuole (CCV). The bacterium encodes a type 4B secretion system (T4BSS) that delivers effector proteins into the host cell. Disruption of C. burnetii T4BSS effector export abrogates CCV biogenesis and bacterial replication. Over 150 C. burnetii T4BSS substrates have been designated often based on heterologous protein translocation by the Legionella pneumophila T4BSS. Cross-genome comparisons predict that many of these T4BSS substrates are truncated or absent in the acute-disease reference strain C. burnetii Nine Mile. This study investigated the function of 32 proteins conserved among diverse C. burnetii genomes that are reported to be T4BSS substrates. Despite being previously designated T4BSS substrates, many of the proteins were not translocated by C. burnetii when expressed fused to the CyaA or BlaM reporter tags. CRISPR interference (CRISPRi) indicated that of the validated C. burnetii T4BSS substrates, CBU0122, CBU1752, CBU1825, and CBU2007 promote C. burnetii replication in THP-1 cells and CCV biogenesis in Vero cells. When expressed in HeLa cells tagged at its C or N terminus with mCherry, CBU0122 localized to the CCV membrane and the mitochondria, respectively. Collectively, these data further define the repertoire of bona fide C. burnetii T4BSS substrates. IMPORTANCE Coxiella burnetii secretes effector proteins via a T4BSS that are required for successful infection. Over 150 C. burnetii proteins are reported to be T4BSS substrates and often by default considered putative effectors, but few have assigned functions. Many C. burnetii proteins were designated T4BSS substrates using heterologous secretion assays in L. pneumophila and/or have coding sequences that are absent or pseudogenized in clinically relevant C. burnetii strains. This study examined 32 previously reported T4BSS substrates that are conserved among C. burnetii genomes. Of the proteins tested that were previously designated T4BSS substrates using L. pneumophila, most were not exported by C. burnetii. Several T4BSS substrates that were validated in C. burnetii also promoted pathogen intracellular replication and one trafficked to late endosomes and the mitochondria in a manner suggestive of effector activity. This study identified several bona fide C. burnetii T4BSS substrates and further refined the methodological criteria for their designation.
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Affiliation(s)
- Charles L. Larson
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
- Innate Immunity and Pathogenesis Section, Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
| | - Willis Pullman
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
| | - Paul A. Beare
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
- Genomics Research Section, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
| | - Robert A. Heinzen
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
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11
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Kodori M, Amani J, Meshkat Z, Ahmadi A. Coxiella burnetii Pathogenesis: Emphasizing the Role of the Autophagic Pathway. ARCHIVES OF RAZI INSTITUTE 2023; 78:785-796. [PMID: 38028822 PMCID: PMC10657931 DOI: 10.22092/ari.2023.361161.2636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 01/29/2023] [Accepted: 03/04/2023] [Indexed: 12/01/2023]
Abstract
Coxiella burnetii (C. burnetii), the etiological agent of the Q fever disease, ranks among the most sporadic and persistent global public health concerns. Ruminants are the principal source of human infections and diseases present in both acute and chronic forms. This bacterium is an intracellular pathogen that can survive and reproduce under acidic (pH 4 to 5) and harsh circumstances that contain Coxiella-containing vacuoles. By undermining the autophagy defense system of the host cell, C. burnetii is able to take advantage of the autophagy pathway, which allows it to improve the movement of nutrients and the membrane, thereby extending the vacuole of the reproducing bacteria. For this method to work, it requires the participation of many bacterial effector proteins. In addition, the precise and prompt identification of the causative agent of an acute disease has the potential to delay the onset of its chronic form. Moreover, to make accurate and rapid diagnoses, it is necessary to create diagnostic devices. This review summarizes the most recent research on the epidemiology, pathogenesis, and diagnosis approaches of C. burnetii. This study also explored the complicated relationships between C. burnetii and the autophagic pathway, which are essential for intracellular reproduction and survival in host cells for the infection to be effective.
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Affiliation(s)
- M Kodori
- Molecular Biology Research Center, Systems Biology and Poisonings Institute, Baqiyatallah University, of Medical Sciences, Tehran, Iran
- Non Communicable Diseases Research Center, Bam University of Medical Sciences, Bam, the Islamic Republic of Iran
| | - J Amani
- Applied Microbiology Research Center, Systems Biology and Poisonings Institute, Baqiyatallah University, of Medical Sciences, Tehran, Iran
| | - Z Meshkat
- Department of Microbiology and Virology, Faculty of Medicine, Mashhad University of Medical Sciences, Mashhad, Iran
| | - A Ahmadi
- Molecular Biology Research Center, Systems Biology and Poisonings Institute, Baqiyatallah University, of Medical Sciences, Tehran, Iran
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12
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Ganesan S, Alvarez NN, Steiner S, Fowler KM, Corona AK, Roy CR. Syntaxin 11 Contributes to the Interferon-Inducible Restriction of Coxiella burnetii Intracellular Infection. mBio 2023; 14:e0354522. [PMID: 36728431 PMCID: PMC9972978 DOI: 10.1128/mbio.03545-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Accepted: 01/04/2023] [Indexed: 02/03/2023] Open
Abstract
There is a limited understanding of host defense mechanisms targeting intracellular pathogens that proliferate in a lysosome. Coxiella burnetii is a model bacterial pathogen capable of replicating in the hydrolytic and acidic environment of the lysosome. It has been shown that gamma interferon (IFNγ)-stimulated host cells restrict C. burnetii replication by a mechanism that involves host IDO1 depletion of tryptophan. Host cells deficient in IDO1 activity, however, retain the ability to restrict C. burnetii replication when stimulated with IFNγ, which suggests additional mechanisms of host defense. This study identified syntaxin 11 (STX11) as a host protein that contributes to IFNγ-mediated suppression of C. burnetii replication. STX11 is a SNARE protein; SNARE proteins are proteins that mediate fusion of host vesicles with specific subcellular organelles. Depletion of STX11 using either small interfering RNA (siRNA)- or CRISPR-based approaches enhanced C. burnetii replication intracellularly. Stable expression of STX11 reduced C. burnetii replication in epithelial cells and macrophages, which indicates that this STX11-dependent cell-autonomous response is operational in multiple cell types and can function independently of other IFNγ-induced factors. Fluorescently tagged STX11 localized to the Coxiella-containing vacuole (CCV), and STX11 restriction was found to involve an interaction with STX8. Thus, STX11 regulates a vesicle fusion pathway that limits replication of this intracellular pathogen in a lysosome-derived organelle. IMPORTANCE Cell intrinsic defense mechanisms are used by eukaryotic cells to restrict the replication and dissemination of pathogens. This study identified a human protein called syntaxin 11 (STX11) as a host restriction factor that inhibits the intracellular replication of Coxiella burnetii. Syntaxins regulate the delivery of cargo inside vesicles by promoting specific membrane fusion events between donor and acceptor vesicles. Data presented here demonstrate that STX11 regulates an immunological defense pathway that controls replication of pathogens in lysosome-derived organelles, which provides new insight into the function of this SNARE protein.
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Affiliation(s)
- Sandhya Ganesan
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Natalie N. Alvarez
- Department of Pediatrics, School of Medicine, Emory University, Atlanta, Georgia, USA
| | - Samuel Steiner
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Karen M. Fowler
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Abigail K. Corona
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Craig R. Roy
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, USA
- Department of Immunobiology, Yale University School of Medicine, New Haven, Connecticut, USA
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13
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Yadav A, Brewer MN, Elshahed MS, Shaw EI. Comparative Transcriptomics and Genomics from Continuous Axenic Media Growth Identifies Coxiella burnetii Intracellular Survival Strategies. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.06.527305. [PMID: 36798183 PMCID: PMC9934583 DOI: 10.1101/2023.02.06.527305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
Coxiella burnetii (Cb) is an obligate intracellular pathogen in nature and the causative agent of acute Q fever as well as chronic diseases. In an effort to identify genes and proteins crucial to their normal intracellular growth lifestyle, we applied a "Reverse evolution" approach where the avirulent Nine Mile Phase II strain of Cb was grown for 67 passages in chemically defined ACCM-D media and gene expression patterns and genome integrity from various passages was compared to passage number one following intracellular growth. Transcriptomic analysis identified a marked downregulation of the structural components of the type 4B secretion system (T4BSS), the general secretory (sec) pathway, as well as 14 out of 118 previously identified genes encoding effector proteins. Additional downregulated pathogenicity determinants genes included several chaperones, LPS, and peptidoglycan biosynthesis. A general marked downregulation of central metabolic pathways was also observed, which was balanced by a marked upregulation of genes encoding transporters. This pattern reflected the richness of the media and diminishing anabolic and ATP-generation needs. Finally, genomic sequencing and comparative genomic analysis demonstrated an extremely low level of mutation across passages, despite the observed Cb gene expression changes following acclimation to axenic media.
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Affiliation(s)
- Archana Yadav
- Department of Microbiology and Molecular Genetics. Oklahoma State University. Stillwater, OK.USA
| | - Melissa N. Brewer
- Department of Microbiology and Molecular Genetics. Oklahoma State University. Stillwater, OK.USA
- Biological Sciences. Southeastern Oklahoma State University. Durant, OK. USA
| | - Mostafa S. Elshahed
- Department of Microbiology and Molecular Genetics. Oklahoma State University. Stillwater, OK.USA
| | - Edward I. Shaw
- Department of Microbiology and Molecular Genetics. Oklahoma State University. Stillwater, OK.USA
- Department of Biomedical Sciences. Philadelphia College of Osteopathic Medicine. Moultrie, GA. USA
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14
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Metters G, Hemsley C, Norville I, Titball R. Identification of essential genes in Coxiella burnetii. Microb Genom 2023; 9:mgen000944. [PMID: 36723494 PMCID: PMC9997736 DOI: 10.1099/mgen.0.000944] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Coxiella burnetii is an intracellular pathogen responsible for causing Q fever in humans, a disease with varied presentations ranging from a mild flu-like sickness to a debilitating illness that can result in endocarditis. The intracellular lifestyle of C. burnetii is unique, residing in an acidic phagolysosome-like compartment within host cells. An understanding of the core molecular biology of C. burnetii will greatly increase our understanding of C. burnetii growth, survival and pathogenesis. We used transposon-directed insertion site sequencing (TraDIS) to reveal C. burnetii Nine Mile Phase II genes fundamental for growth and in vitro survival. Screening a transposon library containing >10 000 unique transposon mutants revealed 512 predicted essential genes. Essential routes of synthesis were identified for the mevalonate pathway, as well as peptidoglycan and biotin synthesis. Some essential genes identified (e.g. predicted type IV secretion system effector genes) are typically considered to be associated with C. burnetii virulence, a caveat concerning the axenic media used in the study. Investigation into the conservation of the essential genes identified revealed that 78 % are conserved across all C. burnetii strains sequenced to date, which probably play critical functions. This is the first report of a whole genome transposon screen in C. burnetii that has been undertaken for the identification of essential genes.
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Affiliation(s)
- Georgie Metters
- Department of Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4QD, UK.,Defence Science and Technology Laboratories, CBR Division, Porton Down, Salisbury SP4 0JQ, UK
| | - Claudia Hemsley
- Department of Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4QD, UK.,Present address: Molecular Microbiology Division, School of Life Sciences, University of Dundee, Dundee, DD1 5AA, UK
| | - Isobel Norville
- Department of Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4QD, UK.,Defence Science and Technology Laboratories, CBR Division, Porton Down, Salisbury SP4 0JQ, UK
| | - Richard Titball
- Department of Biosciences, College of Life and Environmental Sciences, University of Exeter, Exeter EX4 4QD, UK
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15
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Yadav A, Brewer MN, Elshahed MS, Shaw EI. Comparative transcriptomics and genomics from continuous axenic media growth identifies Coxiella burnetii intracellular survival strategies. Pathog Dis 2023; 81:ftad009. [PMID: 37193663 PMCID: PMC10237335 DOI: 10.1093/femspd/ftad009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2023] [Revised: 04/17/2023] [Accepted: 05/15/2023] [Indexed: 05/18/2023] Open
Abstract
Coxiella burnetii (Cb) is an obligate intracellular pathogen in nature and the causative agent of acute Q fever as well as chronic diseases. In an effort to identify genes and proteins crucial to their normal intracellular growth lifestyle, we applied a 'reverse evolution' approach where the avirulent Nine Mile Phase II strain of Cb was grown for 67 passages in chemically defined ACCM-D media and gene expression patterns and genome integrity from various passages was compared to passage number one following intracellular growth. Transcriptomic analysis identified a marked downregulation of the structural components of the type 4B secretion system (T4BSS), the general secretory (Sec) pathway, as well as 14 out of 118 previously identified genes encoding effector proteins. Additional downregulated pathogenicity determinants genes included several chaperones, LPS, and peptidoglycan biosynthesis. A general marked downregulation of central metabolic pathways was also observed, which was balanced by a marked upregulation of genes encoding transporters. This pattern reflected the richness of the media and diminishing anabolic, and ATP-generation needs. Finally, genomic sequencing and comparative genomic analysis demonstrated an extremely low level of mutation across passages, despite the observed Cb gene expression changes following acclimation to axenic media.
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Affiliation(s)
- Archana Yadav
- Department of Microbiology and Molecular Genetics, Oklahoma State University,, 74078 Stillwater, OK, United States
| | - Melissa N Brewer
- Department of Microbiology and Molecular Genetics, Oklahoma State University,, 74078 Stillwater, OK, United States
- Biological Sciences, Southeastern Oklahoma State University, 74078 Durant, OK, United States
| | - Mostafa S Elshahed
- Department of Microbiology and Molecular Genetics, Oklahoma State University,, 74078 Stillwater, OK, United States
| | - Edward I Shaw
- Department of Microbiology and Molecular Genetics, Oklahoma State University,, 74078 Stillwater, OK, United States
- Department of Biomedical Sciences, Philadelphia College of Osteopathic Medicine, 74078 Moultrie, GA, United States
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16
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Wachter S, Cockrell DC, Miller HE, Virtaneva K, Kanakabandi K, Darwitz B, Heinzen RA, Beare PA. The endogenous Coxiella burnetii plasmid encodes a functional toxin-antitoxin system. Mol Microbiol 2022; 118:744-764. [PMID: 36385554 PMCID: PMC10098735 DOI: 10.1111/mmi.15001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2022] [Revised: 10/25/2022] [Accepted: 11/08/2022] [Indexed: 11/18/2022]
Abstract
Coxiella burnetii is the causative agent of Q fever. All C. burnetii isolates encode either an autonomously replicating plasmid (QpH1, QpDG, QpRS, or QpDV) or QpRS-like chromosomally integrated plasmid sequences. The role of the ORFs present in these sequences is unknown. Here, the role of the ORFs encoded on QpH1 was investigated. Using a new C. burnetii shuttle vector (pB-TyrB-QpH1ori), we cured the C. burnetii Nine Mile Phase II strain of QpH1. The ΔQpH1 strain grew normally in axenic media but had a significant growth defect in Vero cells, indicating QpH1 was important for C. burnetii virulence. We developed an inducible CRISPR interference system to examine the role of individual QpH1 plasmid genes. CRISPRi of cbuA0027 resulted in significant growth defects in axenic media and THP-1 cells. The cbuA0028/cbuA0027 operon encodes CBUA0028 (ToxP) and CBUA0027 (AntitoxP), which are homologous to the HigB2 toxin and HigA2 antitoxin, respectively, from Vibrio cholerae. Consistent with toxin-antitoxin systems, overexpression of toxP resulted in a severe intracellular growth defect that was rescued by co-expression of antitoxP. ToxP inhibited protein translation. AntitoxP bound the toxP promoter (PtoxP) and ToxP, with the resulting complex binding also PtoxP. In summary, our data indicate that C. burnetii maintains an autonomously replicating plasmid because of a plasmid-based toxin-antitoxin system.
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Affiliation(s)
- Shaun Wachter
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA.,Vaccine and Infectious Disease Organization, Saskatoon, Saskatchewan, Canada
| | - Diane C Cockrell
- Vector-Pathogen-Host Interaction unit, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
| | | | - Kimmo Virtaneva
- Genomics Research Section, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
| | - Kishore Kanakabandi
- Genomics Research Section, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
| | - Benjamin Darwitz
- Department of Microbiology and Immunology, University of North Carolina, Chapel Hill, North Carolina, USA
| | - Robert A Heinzen
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
| | - Paul A Beare
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA.,Genomics Research Section, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, USA
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17
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Fu M, Liu Y, Wang G, Wang P, Zhang J, Chen C, Zhao M, Zhang S, Jiao J, Ouyang X, Yu Y, Wen B, He C, Wang J, Zhou D, Xiong X. A protein–protein interaction map reveals that the Coxiella burnetii effector CirB inhibits host proteasome activity. PLoS Pathog 2022; 18:e1010660. [PMID: 35816513 PMCID: PMC9273094 DOI: 10.1371/journal.ppat.1010660] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Accepted: 06/09/2022] [Indexed: 12/19/2022] Open
Abstract
Coxiella burnetii is the etiological agent of the zoonotic disease Q fever, which is featured by its ability to replicate in acid vacuoles resembling the lysosomal network. One key virulence determinant of C. burnetii is the Dot/Icm system that transfers more than 150 effector proteins into host cells. These effectors function to construct the lysosome-like compartment permissive for bacterial replication, but the functions of most of these effectors remain elusive. In this study, we used an affinity tag purification mass spectrometry (AP-MS) approach to generate a C. burnetii-human protein-protein interaction (PPI) map involving 53 C. burnetii effectors and 3480 host proteins. This PPI map revealed that the C. burnetii effector CBU0425 (designated CirB) interacts with most subunits of the 20S core proteasome. We found that ectopically expressed CirB inhibits hydrolytic activity of the proteasome. In addition, overexpression of CirB in C. burnetii caused dramatic inhibition of proteasome activity in host cells, while knocking down CirB expression alleviated such inhibitory effects. Moreover, we showed that a region of CirB that spans residues 91–120 binds to the proteasome subunit PSMB5 (beta 5). Finally, PSMB5 knockdown promotes C. burnetii virulence, highlighting the importance of proteasome activity modulation during the course of C. burnetii infection. As the causative agent of Q fever, C. burnetii colonizes host cells by transferring effector proteins into the host cytoplasm through its Dot/Icm secretion system to construct a replicative vacuole. The function of effectors remains largely unknown. Here, we performed a large-scale AP-MS screen to analyze the interactions among C. burnetii effectors and human proteins. These analyses found that CirB functions as an inhibitor of host proteasome activity, revealing that proteasome activity is important for intracellular survival of C. burnetii. Our data have laid the foundation for future exploring the molecular mechanisms underlying the roles of C. burnetii effectors in its virulence and for the identification of novel potential drug targets for the development of novel therapeutic treatment for C. burnetii infection.
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Affiliation(s)
- Mengjiao Fu
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Academy of Military Medicine Sciences, Fengtai, Beijing,China
| | - Yuchen Liu
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, National Center for Protein Sciences, Beijing Institute of Lifeomics, Beijing, China
| | - Guannan Wang
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing, China
| | - Peng Wang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Academy of Military Medicine Sciences, Fengtai, Beijing,China
| | - Jianing Zhang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Academy of Military Medicine Sciences, Fengtai, Beijing,China
| | - Chen Chen
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California, United States of America
| | - Mingliang Zhao
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Academy of Military Medicine Sciences, Fengtai, Beijing,China
| | - Shan Zhang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Academy of Military Medicine Sciences, Fengtai, Beijing,China
| | - Jun Jiao
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Academy of Military Medicine Sciences, Fengtai, Beijing,China
| | - Xuan Ouyang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Academy of Military Medicine Sciences, Fengtai, Beijing,China
| | - Yonghui Yu
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Academy of Military Medicine Sciences, Fengtai, Beijing,China
| | - Bohai Wen
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Academy of Military Medicine Sciences, Fengtai, Beijing,China
| | - Chengzhi He
- Beijing Advanced Innovation Center for Soft Matter Science and Engineering, Beijing University of Chemical Technology, Beijing, China
| | - Jian Wang
- State Key Laboratory of Proteomics, Beijing Proteome Research Center, National Center for Protein Sciences, Beijing Institute of Lifeomics, Beijing, China
| | - Dongsheng Zhou
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Academy of Military Medicine Sciences, Fengtai, Beijing,China
- * E-mail: , (DZ); (XX)
| | - Xiaolu Xiong
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Academy of Military Medicine Sciences, Fengtai, Beijing,China
- * E-mail: , (DZ); (XX)
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18
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Coxiella burnetii Plasmid Effector B Promotes LC3-II Accumulation and Contributes To Bacterial Virulence in a SCID Mouse Model. Infect Immun 2022; 90:e0001622. [PMID: 35587202 DOI: 10.1128/iai.00016-22] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Coxiella burnetii, the causative agent of zoonotic Q fever, is characterized by replicating inside the lysosome-derived Coxiella-containing vacuole (CCV) in host cells. Some effector proteins secreted by C. burnetii have been reported to be involved in the manipulation of autophagy to facilitate the development of CCVs and bacterial replication. Here, we found that the Coxiella plasmid effector B (CpeB) localizes on vacuole membrane targeted by LC3 and LAMP1 and promotes LC3-II accumulation. Meanwhile, the C. burnetii strain lacking the QpH1 plasmid induced less LC3-II accumulation, which was accompanied by smaller CCVs and lower bacterial loads in THP-1 cells. Expression of CpeB in the strain lacking QpH1 led to restoration in LC3-II accumulation but had no effect on the smaller CCV phenotype. In the severe combined immune deficiency (SCID) mouse model, infections with the strain expressing CpeB led to significantly higher bacterial burdens in the spleen and liver than its parent strain devoid of QpH1. We also found that CpeB targets Rab11a to promote LC3-II accumulation. Intratracheally inoculated C. burnetii resulted in lower bacterial burdens and milder lung lesions in Rab11a conditional knockout (Rab11a-/- CKO) mice. Collectively, these results suggest that CpeB promotes C. burnetii virulence by inducing LC3-II accumulation via a pathway involving Rab11a.
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19
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Cheng E, Dorjsuren D, Lehman S, Larson CL, Titus SA, Sun H, Zakharov A, Rai G, Heinzen RA, Simeonov A, Machner MP. A Comprehensive Phenotypic Screening Strategy to Identify Modulators of Cargo Translocation by the Bacterial Type IVB Secretion System. mBio 2022; 13:e0024022. [PMID: 35258332 PMCID: PMC9040768 DOI: 10.1128/mbio.00240-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Accepted: 02/08/2022] [Indexed: 02/03/2023] Open
Abstract
Bacterial type IV secretion systems (T4SSs) are macromolecular machines that translocate effector proteins across multiple membranes into infected host cells. Loss of function mutations in genes encoding protein components of the T4SS render bacteria avirulent, highlighting the attractiveness of T4SSs as drug targets. Here, we designed an automated high-throughput screening approach for the identification of compounds that interfere with the delivery of a reporter-effector fusion protein from Legionella pneumophila into RAW264.7 mouse macrophages. Using a fluorescence resonance energy transfer (FRET)-based detection assay in a bacteria/macrophage coculture format, we screened a library of over 18,000 compounds and, upon vetting compound candidates in a variety of in vitro and cell-based secondary screens, isolated several hits that efficiently interfered with biological processes that depend on a functional T4SS, such as intracellular bacterial proliferation or lysosomal avoidance, but had no detectable effect on L. pneumophila growth in culture medium, conditions under which the T4SS is dispensable. Notably, the same hit compounds also attenuated, to varying degrees, effector delivery by the closely related T4SS from Coxiella burnetii, notably without impacting growth of this organism within synthetic media. Together, these results support the idea that interference with T4SS function is a possible therapeutic intervention strategy, and the emerging compounds provide tools to interrogate at a molecular level the regulation and dynamics of these virulence-critical translocation machines. IMPORTANCE Multi-drug-resistant pathogens are an emerging threat to human health. Because conventional antibiotics target not only the pathogen but also eradicate the beneficial microbiota, they often cause additional clinical complications. Thus, there is an urgent need for the development of "smarter" therapeutics that selectively target pathogens without affecting beneficial commensals. The bacterial type IV secretion system (T4SS) is essential for the virulence of a variety of pathogens but dispensable for bacterial viability in general and can, thus, be considered a pathogen's Achilles heel. By identifying small molecules that interfere with cargo delivery by the T4SS from two important human pathogens, Legionella pneumophila and Coxiella burnetii, our study represents the first step in our pursuit toward precision medicine by developing pathogen-selective therapeutics capable of treating the infections without causing harm to commensal bacteria.
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Affiliation(s)
- Eric Cheng
- Division of Molecular and Cellular Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA
| | - Dorjbal Dorjsuren
- Division of Preclinical Innovation, National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland, USA
| | - Stephanie Lehman
- Division of Molecular and Cellular Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA
| | - Charles L. Larson
- Laboratory of Bacteriology, Coxiella Pathogenesis Section, National Institute of Allergy and Infectious Diseases, Rocky Mountain Laboratories, Hamilton, Montana, USA
| | - Steven A. Titus
- Division of Preclinical Innovation, National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland, USA
| | - Hongmao Sun
- Division of Preclinical Innovation, National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland, USA
| | - Alexey Zakharov
- Division of Preclinical Innovation, National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland, USA
| | - Ganesha Rai
- Division of Preclinical Innovation, National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland, USA
| | - Robert A. Heinzen
- Laboratory of Bacteriology, Coxiella Pathogenesis Section, National Institute of Allergy and Infectious Diseases, Rocky Mountain Laboratories, Hamilton, Montana, USA
| | - Anton Simeonov
- Division of Preclinical Innovation, National Center for Advancing Translational Sciences, National Institutes of Health, Rockville, Maryland, USA
| | - Matthias P. Machner
- Division of Molecular and Cellular Biology, Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland, USA
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20
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Cordsmeier A, Rinkel S, Jeninga M, Schulze-Luehrmann J, Ölke M, Schmid B, Hasler D, Meister G, Häcker G, Petter M, Beare PA, Lührmann A. The Coxiella burnetii T4SS effector protein AnkG hijacks the 7SK small nuclear ribonucleoprotein complex for reprogramming host cell transcription. PLoS Pathog 2022; 18:e1010266. [PMID: 35134097 PMCID: PMC8824381 DOI: 10.1371/journal.ppat.1010266] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 01/10/2022] [Indexed: 11/24/2022] Open
Abstract
Inhibition of host cell apoptosis is crucial for survival and replication of several intracellular bacterial pathogens. To interfere with apoptotic pathways, some pathogens use specialized secretion systems to inject bacterial effector proteins into the host cell cytosol. One of these pathogens is the obligate intracellular bacterium Coxiella burnetii, the etiological agent of the zoonotic disease Q fever. In this study, we analyzed the molecular activity of the anti-apoptotic T4SS effector protein AnkG (CBU0781) to understand how C. burnetii manipulates host cell viability. We demonstrate by co- and RNA-immunoprecipitation that AnkG binds to the host cell DExD box RNA helicase 21 (DDX21) as well as to the host cell 7SK small nuclear ribonucleoprotein (7SK snRNP) complex, an important regulator of the positive transcription elongation factor b (P-TEFb). The co-immunoprecipitation of AnkG with DDX21 is probably mediated by salt bridges and is independent of AnkG-7SK snRNP binding, and vice versa. It is known that DDX21 facilitates the release of P-TEFb from the 7SK snRNP complex. Consistent with the documented function of released P-TEFb in RNA Pol II pause release, RNA sequencing experiments confirmed AnkG-mediated transcriptional reprogramming and showed that expression of genes involved in apoptosis, trafficking, and transcription are influenced by AnkG. Importantly, DDX21 and P-TEFb are both essential for AnkG-mediated inhibition of host cell apoptosis, emphasizing the significance of the interaction of AnkG with both, the DDX21 protein and the 7SK RNA. In line with a critical function of AnkG in pathogenesis, the AnkG deletion C. burnetii strain was severely affected in its ability to inhibit host cell apoptosis and to generate a replicative C. burnetii-containing vacuole. In conclusion, the interference with the activity of regulatory host cell RNAs mediated by a bacterial effector protein represent a novel mechanism through which C. burnetii modulates host cell transcription, thereby enhancing permissiveness to bacterial infection. For intracellular replication, Coxiella burnetii depends on a functional type IV secretion system, which is utilized to inject ~150 virulence factors, so called effector proteins, into the host cell cytosol. Activities have only been established for few of them. These effector proteins interfere with vesicular trafficking, autophagy, lipid metabolism, apoptosis, and transcription by binding and manipulating the activity of host cell proteins. Here, we report that the C. burnetii T4SS effector protein AnkG (CBU0781, Q83DF6) binds to the host cell DExD box helicase 21 (DDX21) as well as to several host cell RNAs, including the small regulatory 7SK RNA, which is an important regulator of the positive elongation factor b (pTEFb). AnkG interferes with the function of the 7SK small nuclear ribonucleoprotein (7SK snRNP) complex, leading to significant changes in host cell transcription and ensuring host cell survival. AnkG activity is essential for efficient intracellular replication of C. burnetii and its ability to inhibit apoptosis. In summary, we identified a novel process by which a bacterial effector protein manipulates the host cell for its own benefit.
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Affiliation(s)
- Arne Cordsmeier
- Mikrobiologisches Institut, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Sven Rinkel
- Mikrobiologisches Institut, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Myriam Jeninga
- Mikrobiologisches Institut, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Jan Schulze-Luehrmann
- Mikrobiologisches Institut, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Martha Ölke
- Mikrobiologisches Institut, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Benedikt Schmid
- Lehrstuhl für Biotechnik, Department Biologie, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Daniele Hasler
- Biochemistry Center Regensburg (BZR), Laboratory for RNA Biology, University of Regensburg, Regensburg, Germany
| | - Gunter Meister
- Biochemistry Center Regensburg (BZR), Laboratory for RNA Biology, University of Regensburg, Regensburg, Germany
| | - Georg Häcker
- Faculty of Medicine, Institute of Medical Microbiology and Hygiene, Medical Center-University of Freiburg, Freiburg, Germany
| | - Michaela Petter
- Mikrobiologisches Institut, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Paul A. Beare
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
| | - Anja Lührmann
- Mikrobiologisches Institut, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
- * E-mail:
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21
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Lau N, Thomas DR, Lee YW, Knodler LA, Newton HJ. Perturbation of ATG16L1 function impairs the biogenesis of Salmonella and Coxiella replication vacuoles. Mol Microbiol 2022; 117:235-251. [PMID: 34874584 PMCID: PMC8844213 DOI: 10.1111/mmi.14858] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Accepted: 12/03/2021] [Indexed: 02/03/2023]
Abstract
Anti-bacterial autophagy, known as xenophagy, is a host innate immune response that targets invading pathogens for degradation. Some intracellular bacteria, such as the enteric pathogen Salmonella enterica serovar Typhimurium (S. Typhimurium), utilize effector proteins to interfere with autophagy. One such S. Typhimurium effector, SopF, inhibits recruitment of ATG16L1 to damaged Salmonella-containing vacuoles (SCVs), thereby inhibiting the host xenophagic response. SopF is also required to maintain the integrity of the SCV during the early stages of infection. Here we show disruption of the SopF-ATG16L1 interaction leads to an increased proportion of cytosolic S. Typhimurium. Furthermore, SopF was utilized as a molecular tool to examine the requirement for ATG16L1 in the intracellular lifestyle of Coxiella burnetii, a bacterium that requires a functional autophagy pathway to replicate efficiently and form a single, spacious vacuole called the Coxiella-containing vacuole (CCV). ATG16L1 is required for CCV expansion and fusion but does not influence C. burnetii replication. In contrast, SopF did not affect CCV formation or replication, demonstrating that the contribution of ATG16L1 to CCV biogenesis is via its role in autophagy, not xenophagy. This study highlights the diverse capabilities of bacterial effector proteins to dissect the molecular details of host-pathogen interactions.
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Affiliation(s)
- Nicole Lau
- The Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria, Australia
| | - David R Thomas
- The Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria, Australia
| | - Yi Wei Lee
- The Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria, Australia
| | - Leigh A Knodler
- The Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria, Australia.,Paul G. Allen School for Global Health, College of Veterinary Medicine, Washington State University, Pullman, Washington, USA
| | - Hayley J Newton
- The Department of Microbiology and Immunology at the Peter Doherty Institute for Infection and Immunity, University of Melbourne, Melbourne, Victoria, Australia
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22
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Osbron CA, Goodman AG. To die or not to die: Programmed cell death responses and their interactions with Coxiella burnetii infection. Mol Microbiol 2022; 117:717-736. [PMID: 35020241 PMCID: PMC9018580 DOI: 10.1111/mmi.14878] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Revised: 01/04/2022] [Accepted: 01/09/2022] [Indexed: 12/01/2022]
Abstract
Coxiella burnetii is a Gram-negative, obligate intracellular, macrophage-tropic bacterium and the causative agent of the zoonotic disease Q fever. The epidemiology of Q fever is associated with the presence of infected animals; sheep, goats, cattle, and humans primarily become infected by inhalation of contaminated aerosols. In humans, the acute phase of the disease is characterized primarily by influenza-like symptoms, and approximately 3-5% of the infected individuals develop chronic infection. C. burnetii infection activates many types of immune responses, and the bacteria's genome encodes for numerous effector proteins that interact with host immune signaling mechanisms. Here, we will discuss two forms of programmed cell death, apoptosis and pyroptosis. Apoptosis is a form of non-inflammatory cell death that leads to phagocytosis of small membrane-bound bodies. Conversely, pyroptosis results in lytic cell death accompanied by the release of proinflammatory cytokines. Both apoptosis and pyroptosis have been implicated in the clearance of intracellular bacterial pathogens, including C. burnetii. Finally, we will discuss the role of autophagy, the degradation of unwanted cellular components, during C. burnetii infection. Together, the review of these forms of programmed cell death will open new research questions aimed at combating this highly infectious pathogen for which treatment options are limited.
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Affiliation(s)
- Chelsea A Osbron
- School of Molecular Biosciences, College of Veterinary Medicine, Washington State University, Pullman, WA, 99164
| | - Alan G Goodman
- School of Molecular Biosciences, College of Veterinary Medicine, Washington State University, Pullman, WA, 99164.,Paul G. Allen School of Global Health, College of Veterinary Medicine, Washington State University, Pullman, WA, 99164
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23
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Jiang C, Huang X, Yao J, Yu L, Wei F, Yang A. The role of membrane contact sites at the bacteria-host interface. Crit Rev Microbiol 2021; 48:270-282. [PMID: 34403642 DOI: 10.1080/1040841x.2021.1961678] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Membrane contact sites (MCSs) refer to the areas of close proximity between heterologous membranes. A growing body of evidence indicates that MCSs are involved in important cellular functions, such as cellular material transfer, organelle biogenesis, and cell growth. Importantly, the study of MCSs at the bacteria-host interface is an emerging popular research topic. Intracellular bacterial pathogens have evolved a variety of fascinating strategies to interfere with MCSs by injecting effectors into infected host cells. Bacteria-containing vacuoles establish direct physical contact with organelles within the host, ensuring vacuolar membrane integrity and energy supply from host organelles and protecting the vacuoles from the host endocytic pathway and lysosomal degradation. An increasing number of bacterial effectors from various bacterial pathogens hijack components of host MCSs to form the vacuole-organelle MCSs for material exchange. MCS-related events have been identified as new mechanisms of microbial pathogenesis to greatly improve bacterial survival and replication within host cells. In this review, we will discuss the recent advances in MCSs at the bacteria-host interface, focussing on the roles of MCSs mediated by bacterial effectors in microbial pathogenesis.
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Affiliation(s)
- Chen Jiang
- School of Life Sciences, Chongqing University, Chongqing, China
| | - Xue Huang
- School of Life Sciences, Chongqing University, Chongqing, China
| | - Jia Yao
- School of Life Sciences, Chongqing University, Chongqing, China
| | - Lihua Yu
- School of Life Sciences, Chongqing University, Chongqing, China
| | - Fujing Wei
- School of Life Sciences, Chongqing University, Chongqing, China
| | - Aimin Yang
- School of Life Sciences, Chongqing University, Chongqing, China
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24
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Neurotransmitter System-Targeting Drugs Antagonize Growth of the Q Fever Agent, Coxiella burnetii, in Human Cells. mSphere 2021; 6:e0044221. [PMID: 34232075 PMCID: PMC8386451 DOI: 10.1128/msphere.00442-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Coxiella burnetii is a highly infectious, intracellular, Gram-negative bacterial pathogen that causes human Q fever, an acute flu-like illness that can progress to chronic endocarditis. C. burnetii is transmitted to humans via aerosols and has long been considered a potential biological warfare agent. Although antibiotics, such as doxycycline, effectively treat acute Q fever, a recently identified antibiotic-resistant strain demonstrates the ability of C. burnetii to resist traditional antimicrobials, and chronic disease is extremely difficult to treat with current options. These findings highlight the need for new Q fever therapeutics, and repurposed drugs that target eukaryotic functions to prevent bacterial replication are of increasing interest in infectious disease. To identify this class of anti-C. burnetii therapeutics, we screened a library of 727 FDA-approved or late-stage clinical trial compounds using a human macrophage-like cell model of infection. Eighty-eight compounds inhibited bacterial replication, including known antibiotics, antipsychotic or antidepressant treatments, antihistamines, and several additional compounds used to treat a variety of conditions. The majority of identified anti-C. burnetii compounds target host neurotransmitter system components. Serotoninergic, dopaminergic, and adrenergic components are among the most highly represented targets and potentially regulate macrophage activation, cytokine production, and autophagy. Overall, our screen identified multiple host-directed compounds that can be pursued for potential use as anti-C. burnetii drugs. IMPORTANCECoxiella burnetii causes the debilitating disease Q fever in humans. This infection is difficult to treat with current antibiotics and can progress to long-term, potentially fatal infection in immunocompromised individuals or when treatment is delayed. Here, we identified many new potential treatment options in the form of drugs that are either FDA approved or have been used in late-stage clinical trials and target human neurotransmitter systems. These compounds are poised for future characterization as nontraditional anti-C. burnetii therapies.
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25
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Burette M, Bonazzi M. From neglected to dissected: How technological advances are leading the way to the study of Coxiella burnetii pathogenesis. Cell Microbiol 2021; 22:e13180. [PMID: 32185905 DOI: 10.1111/cmi.13180] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Revised: 01/08/2020] [Accepted: 01/19/2020] [Indexed: 11/26/2022]
Abstract
Coxiella burnetii is an obligate intracellular bacterial pathogen responsible for severe worldwide outbreaks of the zoonosis Q fever. The remarkable resistance to environmental stress, extremely low infectious dose and ease of dissemination, contributed to the classification of C. burnetii as a class B biothreat. Unique among intracellular pathogens, C. burnetii escapes immune surveillance and replicates within large autophagolysosome-like compartments called Coxiella-containing vacuoles (CCVs). The biogenesis of these compartments depends on the subversion of several host signalling pathways. For years, the obligate intracellular nature of C. burnetii imposed significant experimental obstacles to the study of its pathogenic traits. With the development of an axenic culture medium in 2009, C. burnetii became genetically tractable, thus allowing the implementation of mutagenesis tools and screening approaches to identify its virulence determinants and investigate its complex interaction with host cells. Here, we review the key advances that have contributed to our knowledge of C. burnetii pathogenesis, leading to the rise of this once-neglected pathogen to an exceptional organism to study the intravacuolar lifestyle.
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Affiliation(s)
- Melanie Burette
- IRIM, UMR 9004 CNRS, Université de Montpellier, Montpellier, France
| | - Matteo Bonazzi
- IRIM, UMR 9004 CNRS, Université de Montpellier, Montpellier, France
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26
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Fielden LF, Scott NE, Palmer CS, Khoo CA, Newton HJ, Stojanovski D. Proteomic Identification of Coxiella burnetii Effector Proteins Targeted to the Host Cell Mitochondria During Infection. Mol Cell Proteomics 2020; 20:100005. [PMID: 33177156 PMCID: PMC7950127 DOI: 10.1074/mcp.ra120.002370] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 11/11/2020] [Indexed: 11/06/2022] Open
Abstract
Modulation of the host cell is integral to the survival and replication of microbial pathogens. Several intracellular bacterial pathogens deliver bacterial proteins, termed "effector proteins" into the host cell during infection by sophisticated protein translocation systems, which manipulate cellular processes and functions. The functional contribution of individual effectors is poorly characterized, particularly in intracellular bacterial pathogens with large effector protein repertoires. Technical caveats have limited the capacity to study these proteins during a native infection, with many effector proteins having only been demonstrated to be translocated during over-expression of tagged versions. Here, we developed a novel strategy to examine effector proteins in the context of infection. We coupled a broad, unbiased proteomics-based screen with organelle purification to study the host-pathogen interactions occurring between the host cell mitochondrion and the Gram-negative, Q fever pathogen Coxiella burnetii. We identify four novel mitochondrially-targeted C. burnetii effector proteins, renamed Mitochondrial Coxiella effector protein (Mce) B to E. Examination of the subcellular localization of ectopically expressed proteins confirmed their mitochondrial localization, demonstrating the robustness of our approach. Subsequent biochemical analysis and affinity enrichment proteomics of one of these effector proteins, MceC, revealed the protein localizes to the inner membrane and can interact with components of the mitochondrial quality control machinery. Our study adapts high-sensitivity proteomics to study intracellular host-pathogen interactions, providing a robust strategy to examine the subcellular localization of effector proteins during native infection. This approach could be applied to a range of pathogens and host cell compartments to provide a rich map of effector dynamics throughout infection.
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Affiliation(s)
- Laura F Fielden
- Department of Biochemistry and Molecular Biology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Victoria, Australia
| | - Nichollas E Scott
- Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Catherine S Palmer
- Department of Biochemistry and Molecular Biology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Victoria, Australia
| | - Chen Ai Khoo
- Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
| | - Hayley J Newton
- Department of Microbiology and Immunology, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia.
| | - Diana Stojanovski
- Department of Biochemistry and Molecular Biology and Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, Victoria, Australia.
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27
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Thomas DR, Newton P, Lau N, Newton HJ. Interfering with Autophagy: The Opposing Strategies Deployed by Legionella pneumophila and Coxiella burnetii Effector Proteins. Front Cell Infect Microbiol 2020; 10:599762. [PMID: 33251162 PMCID: PMC7676224 DOI: 10.3389/fcimb.2020.599762] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 10/13/2020] [Indexed: 12/14/2022] Open
Abstract
Autophagy is a fundamental and highly conserved eukaryotic process, responsible for maintaining cellular homeostasis and releasing nutrients during times of starvation. An increasingly important function of autophagy is its role in the cell autonomous immune response; a process known as xenophagy. Intracellular pathogens are engulfed by autophagosomes and targeted to lysosomes to eliminate the threat to the host cell. To counteract this, many intracellular bacterial pathogens have developed unique approaches to overcome, evade, or co-opt host autophagy to facilitate a successful infection. The intracellular bacteria Legionella pneumophila and Coxiella burnetii are able to avoid destruction by the cell, causing Legionnaires' disease and Q fever, respectively. Despite being related and employing homologous Dot/Icm type 4 secretion systems (T4SS) to translocate effector proteins into the host cell, these pathogens have developed their own unique intracellular niches. L. pneumophila evades the host endocytic pathway and instead forms an ER-derived vacuole, while C. burnetii requires delivery to mature, acidified endosomes which it remodels into a large, replicative vacuole. Throughout infection, L. pneumophila effectors act at multiple points to inhibit recognition by xenophagy receptors and disrupt host autophagy, ensuring it avoids fusion with destructive lysosomes. In contrast, C. burnetii employs its effector cohort to control autophagy, hypothesized to facilitate the delivery of nutrients and membrane to support the growing vacuole and replicating bacteria. In this review we explore the effector proteins that these two organisms utilize to modulate the host autophagy pathway in order to survive and replicate. By better understanding how these pathogens manipulate this highly conserved pathway, we can not only develop better treatments for these important human diseases, but also better understand and control autophagy in the context of human health and disease.
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Affiliation(s)
| | | | | | - Hayley J. Newton
- Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, VIC, Australia
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28
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Dragan AL, Voth DE. Coxiella burnetii: international pathogen of mystery. Microbes Infect 2020; 22:100-110. [PMID: 31574310 PMCID: PMC7101257 DOI: 10.1016/j.micinf.2019.09.001] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2019] [Revised: 09/17/2019] [Accepted: 09/18/2019] [Indexed: 12/19/2022]
Abstract
Coxiella burnetii is an intracellular bacterium that causes acute and chronic Q fever. This unique pathogen has been historically challenging to study due to obstacles in genetically manipulating the organism and the inability of small animal models to fully mimic human Q fever. Here, we review the current state of C. burnetii research, highlighting new approaches that allow the mechanistic study of infection in disease relevant settings.
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Affiliation(s)
- Amanda L Dragan
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, AR, 72205, USA
| | - Daniel E Voth
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, AR, 72205, USA.
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29
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Siadous FA, Cantet F, Van Schaik E, Burette M, Allombert J, Lakhani A, Bonaventure B, Goujon C, Samuel J, Bonazzi M, Martinez E. Coxiella effector protein CvpF subverts RAB26-dependent autophagy to promote vacuole biogenesis and virulence. Autophagy 2020; 17:706-722. [PMID: 32116095 PMCID: PMC8032239 DOI: 10.1080/15548627.2020.1728098] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Coxiella burnetii, the etiological agent of the zoonosis Q fever, replicates inside host cells within a large vacuole displaying autolysosomal characteristics. The development of this compartment is mediated by bacterial effectors, which interfere with a number of host membrane trafficking pathways. By screening a Coxiella transposon mutant library, we observed that transposon insertions in cbu0626 led to intracellular replication and vacuole biogenesis defects. Here, we demonstrate that CBU0626 is a novel member of the Coxiella vacuolar protein (Cvp) family of effector proteins, which is translocated by the Dot/Icm secretion system and localizes to vesicles with autolysosomal features as well as Coxiella-containing vacuoles (CCVs). We thus renamed this effector CvpF for Coxiella vacuolar protein F. CvpF specifically interacts with the host small GTPase RAB26, leading to the recruitment of the autophagosomal marker MAP1LC3B/LC3B (microtubule associated protein 1 light chain 3 beta) to CCVs. Importantly, cvpF::Tn mutants were highly attenuated compared to wild-type bacteria in the SCID mouse model of infection, highlighting the importance of CvpF for Coxiella virulence. These results suggest that CvpF manipulates endosomal trafficking and macroautophagy/autophagy induction for optimal C. burnetii vacuole biogenesis. Abbreviations: ACCM: acidified citrate cystein medium; AP: adaptor related protein complex; CCV: Coxiella-containing vacuole; Cvp: Coxiella vacuolar protein; GDI: guanosine nucleotide dissociation inhibitor; GDF: GDI dissociation factor; GEF: guanine exchange factor; LAMP1: lysosomal associated membrane protein 1; MAP1LC3B/LC3B: microtubule associated protein 1 light chain 3 beta; MTORC1: mechanistic target of rapamycin kinase MTOR complex 1; PBS: phosphate-buffered saline; PMA: phorbol myristate acetate; SQSTM1/p62: sequestosome 1; WT: wild-type.
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Affiliation(s)
- Fernande Ayenoue Siadous
- Institut de Recherche en Infectiologie de Montpellier (IRIM) UMR 9004 CNRS, Université de Montpellier, Montpellier, France
| | - Franck Cantet
- Institut de Recherche en Infectiologie de Montpellier (IRIM) UMR 9004 CNRS, Université de Montpellier, Montpellier, France
| | - Erin Van Schaik
- Department of Microbial and Molecular Pathogenesis, Texas A&M Health Science Center College of Medicine, Bryan, TX, USA
| | - Mélanie Burette
- Institut de Recherche en Infectiologie de Montpellier (IRIM) UMR 9004 CNRS, Université de Montpellier, Montpellier, France
| | - Julie Allombert
- Institut de Recherche en Infectiologie de Montpellier (IRIM) UMR 9004 CNRS, Université de Montpellier, Montpellier, France
| | - Anissa Lakhani
- Institut de Recherche en Infectiologie de Montpellier (IRIM) UMR 9004 CNRS, Université de Montpellier, Montpellier, France
| | - Boris Bonaventure
- Institut de Recherche en Infectiologie de Montpellier (IRIM) UMR 9004 CNRS, Université de Montpellier, Montpellier, France
| | - Caroline Goujon
- Institut de Recherche en Infectiologie de Montpellier (IRIM) UMR 9004 CNRS, Université de Montpellier, Montpellier, France
| | - James Samuel
- Department of Microbial and Molecular Pathogenesis, Texas A&M Health Science Center College of Medicine, Bryan, TX, USA
| | - Matteo Bonazzi
- Institut de Recherche en Infectiologie de Montpellier (IRIM) UMR 9004 CNRS, Université de Montpellier, Montpellier, France
| | - Eric Martinez
- Institut de Recherche en Infectiologie de Montpellier (IRIM) UMR 9004 CNRS, Université de Montpellier, Montpellier, France
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30
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Diallo I, Provost P. RNA-Sequencing Analyses of Small Bacterial RNAs and their Emergence as Virulence Factors in Host-Pathogen Interactions. Int J Mol Sci 2020; 21:E1627. [PMID: 32120885 PMCID: PMC7084465 DOI: 10.3390/ijms21051627] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2020] [Revised: 02/22/2020] [Accepted: 02/25/2020] [Indexed: 12/14/2022] Open
Abstract
Proteins have long been considered to be the most prominent factors regulating so-called invasive genes involved in host-pathogen interactions. The possible role of small non-coding RNAs (sRNAs), either intracellular, secreted or packaged in outer membrane vesicles (OMVs), remained unclear until recently. The advent of high-throughput RNA-sequencing (RNA-seq) techniques has accelerated sRNA discovery. RNA-seq radically changed the paradigm on bacterial virulence and pathogenicity to the point that sRNAs are emerging as an important, distinct class of virulence factors in both gram-positive and gram-negative bacteria. The potential of OMVs, as protectors and carriers of these functional, gene regulatory sRNAs between cells, has also provided an additional layer of complexity to the dynamic host-pathogen relationship. Using a non-exhaustive approach and through examples, this review aims to discuss the involvement of sRNAs, either free or loaded in OMVs, in the mechanisms of virulence and pathogenicity during bacterial infection. We provide a brief overview of sRNA origin and importance, and describe the classical and more recent methods of identification that have enabled their discovery, with an emphasis on the theoretical lower limit of RNA sizes considered for RNA sequencing and bioinformatics analyses.
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Affiliation(s)
| | - Patrick Provost
- CHUQ Research Center/CHUL, Department of Microbiology-Infectious Disease and Immunity, Faculty of Medicine, Université Laval, Quebec, QC G1V 0A6, Canada;
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Dependency of Coxiella burnetii Type 4B Secretion on the Chaperone IcmS. J Bacteriol 2019; 201:JB.00431-19. [PMID: 31501284 DOI: 10.1128/jb.00431-19] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Accepted: 09/03/2019] [Indexed: 12/22/2022] Open
Abstract
Macrophage parasitism by Coxiella burnetii, the cause of human Q fever, requires the translocation of proteins with effector functions directly into the host cell cytosol via a Dot/Icm type 4B secretion system (T4BSS). Secretion by the analogous Legionella pneumophila T4BSS involves signal sequences within the C-terminal and internal domains of effector proteins. The cytoplasmic chaperone pair IcmSW promotes secretion and binds internal sites distinct from signal sequences. In the present study, we investigated requirements of C. burnetii IcmS for host cell parasitism and effector translocation. A C. burnetii icmS deletion mutant (ΔicmS) exhibited impaired replication in Vero epithelial cells, deficient formation of the Coxiella-containing vacuole, and aberrant T4BSS secretion. Three secretion phenotypes were identified from a screen of 50 Dot/Icm substrates: IcmS dependent (secreted by only wild-type bacteria), IcmS independent (secreted by both wild-type and ΔicmS bacteria), or IcmS inhibited (secreted by only ΔicmS bacteria). Secretion was assessed for N-terminal or C-terminal truncated forms of CBU0794 and CBU1525. IcmS-inhibited secretion of CBU1525 required a C-terminal secretion signal whereas IcmS-dependent secretion of CBU0794 was directed by C-terminal and internal signals. Interchange of the C-terminal 50 amino acids of CBU0794 and CBU1525 revealed that sites within the C terminus regulate IcmS dependency. Glutathione S-transferase-tagged IcmSW bound internal sequences of IcmS-dependent and -inhibited substrates. Thus, the growth defect of the C. burnetii ΔicmS strain is associated with a loss of T4BSS chaperone activity that both positively and negatively regulates effector translocation.IMPORTANCE The intracellular pathogen Coxiella burnetii employs a type 4B secretion system (T4BSS) that promotes growth by translocating effectors of eukaryotic pathways into host cells. T4BSS regulation modeled in Legionella pneumophila indicates IcmS facilitates effector translocation. Here, we characterized type 4B secretion by a Coxiella ΔicmS mutant that exhibits intracellular growth defects. T4BSS substrates demonstrated increased, equivalent, or decreased secretion by the ΔicmS mutant relative to wild-type Coxiella Similar to the Legionella T4BSS, IcmS dependency in Coxiella was determined by C-terminal and/or internal secretion signals. However, IcmS inhibited secretion of some effectors by Coxiella that were previously shown to be translocated by Legionella Thus, Coxiella has a unique IcmS regulatory mechanism that both positively and negatively regulates T4BSS export.
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A CsrA-Binding, trans-Acting sRNA of Coxiella burnetii Is Necessary for Optimal Intracellular Growth and Vacuole Formation during Early Infection of Host Cells. J Bacteriol 2019; 201:JB.00524-19. [PMID: 31451541 DOI: 10.1128/jb.00524-19] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Accepted: 08/17/2019] [Indexed: 11/20/2022] Open
Abstract
Coxiella burnetii is an obligate intracellular gammaproteobacterium and zoonotic agent of Q fever. We previously identified 15 small noncoding RNAs (sRNAs) of C. burnetii One of them, CbsR12 (Coxiella burnetii small RNA 12), is highly transcribed during axenic growth and becomes more prominent during infection of cultured mammalian cells. Secondary structure predictions of CbsR12 revealed four putative CsrA-binding sites in stem loops with consensus AGGA/ANGGA motifs. We subsequently determined that CbsR12 binds to recombinant C. burnetii CsrA-2, but not CsrA-1, proteins in vitro Moreover, through a combination of in vitro and cell culture assays, we identified several in trans mRNA targets of CbsR12. Of these, we determined that CbsR12 binds and upregulates translation of carA transcripts coding for carbamoyl phosphate synthetase A, an enzyme that catalyzes the first step of pyrimidine biosynthesis. In addition, CbsR12 binds and downregulates translation of metK transcripts coding for S-adenosylmethionine synthetase, a component of the methionine cycle. Furthermore, we found that CbsR12 binds to and downregulates the quantity of cvpD transcripts, coding for a type IVB effector protein, in mammalian cell culture. Finally, we found that CbsR12 is necessary for expansion of Coxiella-containing vacuoles and affects growth rates in a dose-dependent manner in the early phase of infecting THP-1 cells. This is the first characterization of a trans-acting sRNA of C. burnetii and the first example of a bacterial sRNA that regulates both CarA and MetK synthesis. CbsR12 is one of only a few identified trans-acting sRNAs that interacts with CsrA.IMPORTANCE Regulation of metabolism and virulence in C. burnetii is not well understood. Here, we show that C. burnetii small RNA 12 (CbsR12) is highly transcribed in the metabolically active large-cell variant compared to the nonreplicative small-cell variant. We show that CbsR12 directly regulates several genes involved in metabolism, along with a type IV effector gene, in trans In addition, we demonstrate that CbsR12 binds to CsrA-2 in vitro and induces autoaggregation and biofilm formation when transcribed ectopically in Escherichia coli, consistent with other CsrA-sequestering sRNAs. These results implicate CbsR12 in the indirect regulation of a number of genes via CsrA-mediated regulatory activities. The results also support CbsR12 as a crucial regulatory component early on in a mammalian cell infection.
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Noncanonical Inhibition of mTORC1 by Coxiella burnetii Promotes Replication within a Phagolysosome-Like Vacuole. mBio 2019; 10:mBio.02816-18. [PMID: 30723133 PMCID: PMC6428759 DOI: 10.1128/mbio.02816-18] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Coxiella burnetii is an intracellular pathogenic bacterium that replicates within a lysosomal vacuole. Biogenesis of the Coxiella-containing vacuole (CCV) requires effector proteins delivered into the host cell cytosol by the type 4B secretion system (T4BSS). Modifications to lysosomal physiology required for pathogen replication within the CCV are poorly understood. Mammalian (or mechanistic) target of rapamycin complex 1 (mTORC1) is a master kinase that regulates lysosome structure and function. Nutrient deprivation inhibits mTORC1, which promotes cell catabolism in the form of accelerated autophagy and increased lysosome biosynthesis. Here, we report that C. burnetii growth is enhanced by T4BSS-dependent inhibition of mTORC1 that does not activate autophagy. Canonical inhibition of mTORC1 by starvation or inhibitor treatment that induces autophagic flux does not benefit C. burnetii growth. Furthermore, hyperactivation of mTORC1 impairs bacterial replication. These findings indicate that C. burnetii inhibition of mTORC1 without accelerated autophagy promotes bacterial growth. The Q fever agent Coxiella burnetii is a Gram-negative bacterium that invades macrophages and replicates inside a specialized lysosomal vacuole. The pathogen employs a type 4B secretion system (T4BSS) to deliver effector proteins into the host cell that modify the Coxiella-containing vacuole (CCV) into a replication-permissive niche. Mature CCVs are massive degradative organelles that acquire lysosomal proteins. Inhibition of mammalian (or mechanistic) target of rapamycin complex 1 (mTORC1) kinase by nutrient deprivation promotes autophagy and lysosome fusion, as well as activation of the transcription factors TFE3 and TFEB (TFE3/B), which upregulates expression of lysosomal genes. Here, we report that C. burnetii inhibits mTORC1 as evidenced by impaired localization of mTORC1 to endolysosomal membranes and decreased phosphorylation of elF4E-binding protein 1 (4E-BP1) and S6 kinase 1 in infected cells. Infected cells exhibit increased amounts of autophagy-related proteins protein 1A/1B-light chain 3 (LC3) and p62 as well as of activated TFE3. However, C. burnetii did not accelerate autophagy or block autophagic flux triggered by cell starvation. Activation of autophagy or transcription by TFE3/B increased CCV expansion without enhancing bacterial replication. By contrast, knockdown of tuberous sclerosis complex 1 (TSC1) or TSC2, which hyperactivates mTORC1, impaired CCV expansion and bacterial replication. Together, these data demonstrate that specific inhibition of mTORC1 by C. burnetii, but not amplified cell catabolism via autophagy, is required for optimal pathogen replication. These data reveal a complex interplay between lysosomal function and host cell metabolism that regulates C. burnetii intracellular growth.
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Martinez E, Siadous FA, Bonazzi M. Tiny architects: biogenesis of intracellular replicative niches by bacterial pathogens. FEMS Microbiol Rev 2018; 42:425-447. [PMID: 29596635 DOI: 10.1093/femsre/fuy013] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Accepted: 03/26/2018] [Indexed: 11/13/2022] Open
Abstract
Co-evolution of bacterial pathogens with their hosts led to the emergence of a stunning variety of strategies aiming at the evasion of host defences, colonisation of host cells and tissues and, ultimately, the establishment of a successful infection. Pathogenic bacteria are typically classified as extracellular and intracellular; however, intracellular lifestyle comes in many different flavours: some microbes rapidly escape to the cytosol whereas other microbes remain within vacuolar compartments and harness membrane trafficking pathways to generate their host-derived, pathogen-specific replicative niche. Here we review the current knowledge on a variety of vacuolar lifestyles, the effector proteins used by bacteria as tools to take control of the host cell and the main membrane trafficking signalling pathways targeted by vacuolar pathogens as source of membranes and nutrients. Finally, we will also discuss how host cells have developed countermeasures to sense the biogenesis of the aberrant organelles harbouring bacteria. Understanding the dialogue between bacterial and eukaryotic proteins is the key to unravel the molecular mechanisms of infection and in turn, this may lead to the identification of new targets for the development of new antimicrobials.
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Affiliation(s)
- Eric Martinez
- IRIM, University of Montpellier, CNRS, 34293 Montpellier, France
| | | | - Matteo Bonazzi
- IRIM, University of Montpellier, CNRS, 34293 Montpellier, France
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Wang T, Yu Y, Liang X, Luo S, He Z, Sun Z, Jiang Y, Omsland A, Zhou P, Song L. Lipid A Has Significance for Optimal Growth of Coxiella burnetii in Macrophage-Like THP-1 Cells and to a Lesser Extent in Axenic Media and Non-phagocytic Cells. Front Cell Infect Microbiol 2018; 8:192. [PMID: 29938202 PMCID: PMC6002510 DOI: 10.3389/fcimb.2018.00192] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2018] [Accepted: 05/22/2018] [Indexed: 02/02/2023] Open
Abstract
Lipid A is an essential basal component of lipopolysaccharide of most Gram-negative bacteria. Inhibitors targeting LpxC, a conserved enzyme in lipid A biosynthesis, are antibiotic candidates against Gram-negative pathogens. Here we report the characterization of the role of lipid A in Coxiella burnetii growth in axenic media, monkey kidney cells (BGMK and Vero), and macrophage-like THP-1 cells by using a potent LpxC inhibitor -LPC-011. We first determined the susceptibility of C. burnetii LpxC to LPC-011 in a surrogate E. coli model. In E. coli, the minimum inhibitory concentration (MIC) of LPC-011 against C. burnetii LpxC is < 0.05 μg/mL, a value lower than the inhibitor's MIC against E. coli LpxC. Considering the inhibitor's problematic pharmacokinetic properties in vivo and Coxiella's culturing time up to 7 days, the stability of LPC-011 in cell cultures was assessed. We found that regularly changing inhibitor-containing media was required for sustained inhibition of C. burnetii LpxC in cells. Under inhibitor treatment, Coxiella has reduced growth yields in axenic media and during replication in non-phagocytic cells, and has a reduced number of productive vacuoles in such cells. Inhibiting lipid A biosynthesis in C. burnetii by the inhibitor was shown in a phase II strain transformed with chlamydial kdtA. This exogenous KdtA enzyme modifies Coxiella lipid A with an α-Kdo-(2 → 8)-α-Kdo epitope that can be detected by anti-chlamydia genus antibodies. In inhibitor-treated THP-1 cells, Coxiella shows severe growth defects characterized by poor vacuole formation and low growth yields. Coxiella progenies prepared from inhibitor-treated cells retain the capability of normally infecting all tested cells in the absence of the inhibitor, which suggests a dispensable role of lipid A for infection and early vacuole development. In conclusion, our data suggest that lipid A has significance for optimal development of Coxiella-containing vacuoles, and for robust multiplication of C. burnetii in macrophage-like THP-1 cells. Unlike many bacteria, C. burnetii replication in axenic media and non-phagocytic cells was less dependent on normal lipid A biosynthesis.
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Affiliation(s)
- Tao Wang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Yonghui Yu
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Xiaofei Liang
- Department of Chemistry, Duke University, Durham, NC, United States
| | - Shengdong Luo
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Zemin He
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Zhihui Sun
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Yongqiang Jiang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
| | - Anders Omsland
- Paul G. Allen School for Global Animal Health, College of Veterinary Medicine, Washington State University, Pullman, WA, United States
| | - Pei Zhou
- Department of Biochemistry, Duke University Medical Center, Durham, NC, United States
| | - Lihua Song
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology, Beijing, China
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Sanchez SE, Vallejo-Esquerra E, Omsland A. Use of Axenic Culture Tools to StudyCoxiella burnetii. ACTA ACUST UNITED AC 2018; 50:e52. [DOI: 10.1002/cpmc.52] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Savannah E. Sanchez
- Paul G. Allen School for Global Animal Health, College of Veterinary Medicine, Washington State University; Pullman Washington
- School of Molecular Biosciences, College of Veterinary Medicine, Washington State University; Pullman Washington
| | - Eduardo Vallejo-Esquerra
- Paul G. Allen School for Global Animal Health, College of Veterinary Medicine, Washington State University; Pullman Washington
| | - Anders Omsland
- Paul G. Allen School for Global Animal Health, College of Veterinary Medicine, Washington State University; Pullman Washington
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Stead CM, Cockrell DC, Beare PA, Miller HE, Heinzen RA. A Coxiella burnetii phospholipase A homolog pldA is required for optimal growth in macrophages and developmental form lipid remodeling. BMC Microbiol 2018; 18:33. [PMID: 29661138 PMCID: PMC5902883 DOI: 10.1186/s12866-018-1181-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Accepted: 04/09/2018] [Indexed: 04/05/2023] Open
Abstract
BACKGROUND Many gram-negative bacteria produce an outer membrane phospholipase A (PldA) that plays an important role in outer membrane function and is associated with virulence. RESULTS In the current study, we characterized a pldA mutant of Coxiella burnetii, an intracellular gram-negative pathogen and the agent of human Q fever. The C. burnetti pldA open reading frame directs synthesis of a protein with conserved PldA active site residues. A C. burnetii ΔpldA deletion mutant had a significant growth defect in THP-1 macrophages, but not axenic medium, that was rescued by complementation. Thin layer chromatography was employed to assess whether pldA plays a role in remodeling membrane lipids during C. burnetii morphological differentiation. Extracted lipids were analyzed from replicating, logarithmic phase large cell variants (LCVs), non-replicating, stationary phase small cell variants (SCVs), and a mixture of LCVs and SCVs. Similar to Escherichia coli, all three forms contained cardiolipin (CL), phosphatidylglycerol (PG) and phosphatidylethanolamine (PE). However, PE and PG were present in lower quantities in the SCV while three additional lipid species were present in higher quantities. Co-migration with standards tentatively identified two of the three SCV-enriched lipids as lyso-phosphatidylethanolamine, a breakdown product of PE, and free fatty acids, which are generally toxic to bacteria. Developmental form lipid modifications required the activity of PldA. CONCLUSIONS Collectively, these results indicate developmentally-regulated lipid synthesis by C. burnetii contributes to colonization of macrophages and may contribute to the environmental stability and the distinct biological properties of the SCV.
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Affiliation(s)
- Christopher M. Stead
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana USA
- Department of Chemistry, New Mexico Highlands University, Las Vegas, New Mexico USA
| | - Diane C. Cockrell
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana USA
| | - Paul A. Beare
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana USA
| | - Heather E. Miller
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana USA
| | - Robert A. Heinzen
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana USA
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Luedtke BE, Mahapatra S, Lutter EI, Shaw EI. The Coxiella Burnetii type IVB secretion system (T4BSS) component DotA is released/secreted during infection of host cells and during in vitro growth in a T4BSS-dependent manner. Pathog Dis 2018; 75:3753448. [PMID: 28449081 DOI: 10.1093/femspd/ftx047] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Accepted: 04/20/2017] [Indexed: 01/01/2023] Open
Abstract
Coxiella burnetii is a Gram-negative intracellular pathogen and is the causative agent of the zoonotic disease Q fever. To cause disease, C. burnetii requires a functional type IVB secretion system (T4BSS) to transfer effector proteins required for the establishment and maintenance of a membrane-bound parasitophorous vacuole (PV) and further modulation of host cell process. However, it is not clear how the T4BSS interacts with the PV membrane since neither a secretion pilus nor an extracellular pore forming apparatus has not been described. To address this, we used the acidified citrate cysteine medium (ACCM) along with cell culture infection and immunological techniques to identify the cellular and extracellular localization of T4BSS components. Interestingly, we found that DotA and IcmX were secreted/released in a T4BSS-dependent manner into the ACCM. Analysis of C. burnetii-infected cell lines revealed that DotA colocalized with the host cell marker CD63 (LAMP3) at the PV membrane. In the absence of bacterial protein synthesis, DotA also became depleted from the PV membrane. These data are the first to identify the release/secretion of C. burnetii T4BSS components during axenic growth and the interaction of a T4BSS component with the PV membrane during infection of host cells.
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Affiliation(s)
- Brandon E Luedtke
- Department of Biology, University of Nebraska at Kearney, Kearney, NE 68849, USA
| | - Saugata Mahapatra
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK 74078, USA
| | - Erika I Lutter
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK 74078, USA
| | - Edward I Shaw
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK 74078, USA
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Weber MM, Faris R. Subversion of the Endocytic and Secretory Pathways by Bacterial Effector Proteins. Front Cell Dev Biol 2018; 6:1. [PMID: 29417046 PMCID: PMC5787570 DOI: 10.3389/fcell.2018.00001] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2017] [Accepted: 01/09/2018] [Indexed: 12/22/2022] Open
Abstract
Intracellular bacteria have developed numerous strategies to hijack host vesicular trafficking pathways to form their unique replicative niches. To promote intracellular replication, the bacteria must interact with host organelles and modulate host signaling pathways to acquire nutrients and membrane for the growing parasitophorous vacuole all while suppressing activation of the immune response. To facilitate host cell subversion, bacterial pathogens use specialized secretion systems to deliver bacterial virulence factors, termed effectors, into the host cell that mimic, agonize, and/or antagonize the function of host proteins. In this review we will discuss how bacterial effector proteins from Coxiella burnetii, Brucella abortus, Salmonella enterica serovar Typhimurium, Legionella pneumophila, Chlamydia trachomatis, and Orientia tsutsugamushi manipulate the endocytic and secretory pathways. Understanding how bacterial effector proteins manipulate host processes not only gives us keen insight into bacterial pathogenesis, but also enhances our understanding of how eukaryotic membrane trafficking is regulated.
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Affiliation(s)
- Mary M Weber
- Department of Microbiology and Immunology, University of Iowa, Iowa City, IA, United States
| | - Robert Faris
- Department of Microbiology and Immunology, University of Iowa, Iowa City, IA, United States
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Weber MM, Faris R, van Schaik EJ, Samuel JE. Identification and characterization of arginine finger-like motifs, and endosome-lysosome basolateral sorting signals within the Coxiella burnetii type IV secreted effector protein CirA. Microbes Infect 2018; 20:302-307. [PMID: 29331581 PMCID: PMC6021133 DOI: 10.1016/j.micinf.2017.12.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2017] [Revised: 10/17/2017] [Accepted: 12/20/2017] [Indexed: 01/20/2023]
Abstract
Coxiella burnetii is an obligate intracellular pathogen that replicates in an endolysosome-like compartment termed the Coxiella-containing vacuole (CCV). Formation of this unique replicative niche requires delivery of bacterial effector proteins into the host cytosol where they mediate crucial interactions with the host. We previously identified an essential Dot/Icm effector, CirA that is required for intracellular replication and CCV formation. Furthermore, CirA was shown to stimulate the GTPase activity of RhoA in vitro. In the current study, we used a bioinformatics-guided approach and identified three arginine finger-like motifs, often found in Rho GTPase-activating proteins (GAPs) and endosome-lysosome basolateral sorting signals associated with vesicle trafficking. When expressed in mammalian cells, mutation of either endosome-lysosome-basolateral sorting signals or the arginine finger-like motifs rescued stress phenotypes and decreased plasma membrane localization of ectopically expressed CirA. We further demonstrate that endosome-lysosome sorting signals are required for co-localization with Rab5 and Rab7. Collectively our data indicate that arginine finger-like motifs and endosome-lysosome-basolateral sorting signals within CirA are essential for interaction with the host cytoskeleton.
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Affiliation(s)
- Mary M Weber
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, College of Medicine, Bryan, TX, 77807, USA
| | - Robert Faris
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, College of Medicine, Bryan, TX, 77807, USA
| | - Erin J van Schaik
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, College of Medicine, Bryan, TX, 77807, USA
| | - James E Samuel
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, College of Medicine, Bryan, TX, 77807, USA.
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Xiong X, Jiao J, Gregory AE, Wang P, Bi Y, Wang X, Jiang Y, Wen B, Portnoy DA, Samuel JE, Chen C. Identification of Coxiella burnetii CD8+ T-Cell Epitopes and Delivery by Attenuated Listeria monocytogenes as a Vaccine Vector in a C57BL/6 Mouse Model. J Infect Dis 2017; 215:1580-1589. [PMID: 27703037 DOI: 10.1093/infdis/jiw470] [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: 06/09/2016] [Accepted: 09/25/2016] [Indexed: 01/26/2023] Open
Abstract
Coxiella burnetii is a gram-negative bacterium that causes acute and chronic Q fever. Because of the severe adverse effect of whole-cell vaccination, identification of immunodominant antigens of C. burnetii has become a major focus of Q fever vaccine development. We hypothesized that secreted C. burnetii type IV secretion system (T4SS) effectors may represent a major class of CD8+ T-cell antigens, owing to their cytosolic localization. Twenty-nine peptides were identified that elicited robust CD8+ T-cell interferon γ (IFN-γ) recall responses from mice infected with C. burnetii. Interestingly, 22 of 29 epitopes were derived from 17 T4SS-related proteins, none of which were identified as immunodominant antigens by using previous antibody-guided approaches. These epitopes were expressed in an attenuated Listeria monocytogenes vaccine strain. Immunization with recombinant L. monocytogenes vaccines induced a robust CD8+ T-cell response and conferred measurable protection against C. burnetii infection in mice. These data suggested that T4SS effectors represent an important class of C. burnetii antigens that can induce CD8+ T-cell responses. We also showed that attenuated L. monocytogenes vaccine vectors are an efficient antigen-delivery platform that can be used to induce robust protective CD8+ T-cell immune responses against C. burnetii infection.
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Affiliation(s)
- Xiaolu Xiong
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology
| | - Jun Jiao
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology
| | - Anthony E Gregory
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan
| | - Pengcheng Wang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology.,Department of Clinical Laboratory, 105th Hospital of the People's Liberation Army, Hefei, China
| | - Yujing Bi
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology
| | - Xiaoyi Wang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology
| | - Yongqiang Jiang
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology
| | - Bohai Wen
- State Key Laboratory of Pathogen and Biosecurity, Beijing Institute of Microbiology and Epidemiology
| | - Daniel A Portnoy
- Department of Molecular and Cell Biology, University of California, Berkeley
| | - James E Samuel
- Department of Microbial Pathogenesis and Immunology, Texas A&M Health Science Center, Bryan
| | - Chen Chen
- Department of Molecular and Cell Biology, University of California, Berkeley
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Host and Bacterial Factors Control Susceptibility of Drosophila melanogaster to Coxiella burnetii Infection. Infect Immun 2017; 85:IAI.00218-17. [PMID: 28438980 DOI: 10.1128/iai.00218-17] [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: 03/24/2017] [Accepted: 04/17/2017] [Indexed: 12/12/2022] Open
Abstract
Coxiella burnetii is the causative agent of Q fever, a zoonotic disease that threatens both human and animal health. Due to the paucity of experimental animal models, little is known about how host factors interface with bacterial components and affect pathogenesis. Here, we used Drosophila melanogaster, in conjunction with the biosafety level 2 (BSL2) Nine Mile phase II (NMII) clone 4 strain of C. burnetii, as a model to investigate host and bacterial components implicated in infection. We demonstrate that adult Drosophila flies are susceptible to C. burnetii NMII infection and that this bacterial strain, which activates the immune deficiency (IMD) pathway, is able to replicate and cause mortality in the animals. We show that in the absence of Eiger, the only known tumor necrosis factor (TNF) superfamily homolog in Drosophila, Coxiella-infected flies exhibit reduced mortality from infection. We also demonstrate that the Coxiella type 4 secretion system (T4SS) is critical for the formation of the Coxiella-containing vacuole and establishment of infection in Drosophila Altogether, our data reveal that the Drosophila TNF homolog Eiger and the Coxiella T4SS are implicated in the pathogenesis of C. burnetii in flies. The Drosophila/NMII model mimics relevant aspects of the infection in mammals, such as a critical role of host TNF and the bacterial T4SS in pathogenesis. Our work also demonstrates the usefulness of this BSL2 model to investigate both host and Coxiella components implicated in infection.
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A Farnesylated Coxiella burnetii Effector Forms a Multimeric Complex at the Mitochondrial Outer Membrane during Infection. Infect Immun 2017; 85:IAI.01046-16. [PMID: 28242621 DOI: 10.1128/iai.01046-16] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 02/17/2017] [Indexed: 01/16/2023] Open
Abstract
Coxiella burnetii, the causative agent of Q fever, establishes a unique lysosome-derived intracellular niche termed the Coxiella-containing vacuole (CCV). The Dot/Icm-type IVB secretion system is essential for the biogenesis of the CCV and the intracellular replication of Coxiella Effector proteins, translocated into the host cell through this apparatus, act to modulate host trafficking and signaling processes to facilitate CCV development. Here we investigated the role of CBU0077, a conserved Coxiella effector that had previously been observed to localize to lysosomal membranes. CBU0077 was dispensable for the intracellular replication of Coxiella in HeLa and THP-1 cells and did not appear to participate in CCV biogenesis. Intriguingly, native and epitope-tagged CBU0077 produced by Coxiella displayed specific punctate localization at host cell mitochondria. As such, we designated CBU0077 MceA (mitochondrial Coxiellaeffector protein A). Analysis of ectopically expressed MceA truncations revealed that the capacity to traffic to mitochondria is encoded within the first 84 amino acids of this protein. MceA is farnesylated by the host cell; however, this does not impact mitochondrial localization. Examination of mitochondria isolated from infected cells revealed that MceA is specifically integrated into the mitochondrial outer membrane and forms a complex of approximately 120 kDa. Engineering Coxiella to express either MceA tagged with 3×FLAG or MceA tagged with 2×hemagglutinin allowed us to perform immunoprecipitation experiments that showed that MceA forms a homo-oligomeric species at the mitochondrial outer membrane during infection. This research reveals that mitochondria are a bona fide target of Coxiella effectors and MceA is a complex-forming effector at the mitochondrial outer membrane during Coxiella infection.
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Cockrell DC, Long CM, Robertson SJ, Shannon JG, Miller HE, Myers L, Larson CL, Starr T, Beare PA, Heinzen RA. Robust growth of avirulent phase II Coxiella burnetii in bone marrow-derived murine macrophages. PLoS One 2017; 12:e0173528. [PMID: 28278296 PMCID: PMC5344453 DOI: 10.1371/journal.pone.0173528] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Accepted: 02/21/2017] [Indexed: 11/19/2022] Open
Abstract
Published data show that murine bone marrow-derived macrophages (BMDM) restrict growth of avirulent phase II, but not virulent phase I, Coxiella burnetii. Growth restriction of phase II bacteria is thought to result from potentiated recognition of pathogen-associated molecular patterns, which leads to production of inhibitory effector molecules. Past studies have used conditioned medium from L-929 murine fibroblasts as a source of macrophage-colony stimulating factor (M-CSF) to promote differentiation of bone marrow-derived myeloid precursors into macrophages. However, uncharacterized components of conditioned medium, such as variable amounts of type I interferons, can affect macrophage activation status and their permissiveness for infection. In the current study, we show that the C. burnetii Nine Mile phase II (NMII) strain grows robustly in primary macrophages from C57BL/6J mice when bone marrow cells are differentiated with recombinant murine M-CSF (rmM-CSF). Bacteria were readily internalized by BMDM, and replicated within degradative, LAMP1-positive vacuoles to achieve roughly 3 logs of growth over 6 days. Uninfected BMDM did not appreciably express CD38 or Egr2, markers of classically (M1) and alternatively (M2) activated macrophages, respectively, nor did infection change the lack of polarization. In accordance with an M0 phenotype, infected BMDM produced moderate amounts of TNF and nitric oxide. Similar NMII growth results were obtained using C57BL/6J myeloid progenitors immortalized with an estrogen-regulated Hoxb8 (ER-Hoxb8) oncogene. To demonstrate the utility of the ER-Hoxb8 system, myeloid progenitors from natural resistance-associated macrophage protein 1 (Nramp1) C57BL/6J knock-in mice were transduced with ER-Hoxb8, and macrophages were derived from immortalized progenitors using rmM-CSF and infected with NMII. No difference in growth was observed when compared to macrophages from wild type mice, indicating depletion of metal ions by the Nramp1 transporter does not negatively impact NMII growth. Results with NMII were recapitulated in primary macrophages where C57BL/6J Nramp1+ BMDM efficiently killed Salmonella enterica serovar Typhimurium. M-CSF differentiated murine macrophages from bone marrow and conditional ER-Hoxb8 myeloid progenitors will be useful ex vivo models for studying Coxiella-macrophage interactions.
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Affiliation(s)
- Diane C. Cockrell
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
| | - Carrie M. Long
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
| | - Shelly J. Robertson
- Innate Immunity and Pathogenesis Unit, Laboratory of Virology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
| | - Jeffrey G. Shannon
- Plague Section, Laboratory of Zoonotic Pathogens, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
| | - Heather E. Miller
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
| | - Lara Myers
- Retroviral Immunology Section, Laboratory of Persistent Viral Diseases, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
| | - Charles L. Larson
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
| | - Tregei Starr
- Salmonella-Host Cell Interactions Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
| | - Paul A. Beare
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
| | - Robert A. Heinzen
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
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Larson CL, Heinzen RA. High-Content Imaging Reveals Expansion of the Endosomal Compartment during Coxiella burnetii Parasitophorous Vacuole Maturation. Front Cell Infect Microbiol 2017; 7:48. [PMID: 28293541 PMCID: PMC5329641 DOI: 10.3389/fcimb.2017.00048] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Accepted: 02/07/2017] [Indexed: 11/18/2022] Open
Abstract
Coxiella burnetii is an obligate intracellular pathogen and the causative agent of human Q fever. Replication of the bacterium within a large parasitophorous vacuole (PV) resembling a host phagolysosome is required for pathogenesis. PV biogenesis is a pathogen driven process that requires engagement of several host cell vesicular trafficking pathways to acquire vacuole components. The goal of this study was to determine if infection by C. burnetii modulates endolysosomal flux to potentially benefit PV formation. HeLa cells, infected with C. burnetii or left uninfected, were incubated with fluorescent transferrin (Tf) for 0–30 min, and the amount of Tf internalized by cells quantitated by high-content imaging. At 3 and 5 days, but not 1 day post-infection, the maximal amounts of fluorescent Tf internalized by infected cells were significantly greater than uninfected cells. The rates of Tf uptake and recycling were the same for infected and uninfected cells; however, residual Tf persisted in EEA.1 positive compartments adjacent to large PV after 30 min of recycling in the absence of labeled Tf. On average, C. burnetii-infected cells contained significantly more CD63-positive endosomes than uninfected cells. In contrast, cells containing large vacuoles generated by Chlamydia trachomatis exhibited increased rates of Tf internalization without increased CD63 expression. Our results suggest that C. burnetii infection expands the endosomal system to increase capacity for endocytic material. Furthermore, this study demonstrates the power of high-content imaging for measurement of cellular responses to infection by intracellular pathogens.
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Affiliation(s)
- Charles L Larson
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health Hamilton, MT, USA
| | - Robert A Heinzen
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health Hamilton, MT, USA
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van Schaik EJ, Case ED, Martinez E, Bonazzi M, Samuel JE. The SCID Mouse Model for Identifying Virulence Determinants in Coxiella burnetii. Front Cell Infect Microbiol 2017; 7:25. [PMID: 28217558 PMCID: PMC5289997 DOI: 10.3389/fcimb.2017.00025] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 01/19/2017] [Indexed: 01/09/2023] Open
Abstract
Coxiella burnetii is an intracellular, zoonotic pathogen that is the causative agent of Q fever. Infection most frequently occurs after inhalation of contaminated aerosols, which can lead to acute, self-limiting febrile illness or more serve chronic infections such as hepatitis or endocarditis. Macrophages are the principal target cells during infection where C. burnetii resides and replicates within a unique phagolysosome-like compartment, the Coxiella-containing vacuole (CCV). The first virulence determinant described as necessary for infection was full-length lipopolysaccarride (LPS); spontaneous rough mutants (phase II) arise after passage in immuno-incompetent hosts. Phase II C. burnetii are attenuated in immuno-competent animals, but are fully capable of infecting a variety of host cells in vitro. A clonal strain of the Nine Mile isolate (RSA439, clone 4), has a 26 KDa chromosomal deletion that includes LPS biosynthetic genes and is uniquely approved for use in BL2/ABL2 conditions. With the advances of axenic media and genetic tools for C. burnetii research, the characterization of novel virulence determinants is ongoing and almost exclusively performed using this attenuated clone. A major problem with predicting essential virulence loci with RSA439 is that, although some cell-autonomous phenotypes can be assessed in tissue culture, no animal model for assessing pathogenesis has been defined. Here we describe the use of SCID mice for predicting virulence factors of C. burnetii, in either independent or competitive infections. We propose that this model allows for the identification of mutations that are competent for intracellular replication in vitro, but attenuated for growth in vivo and predict essential innate immune responses modulated by the pathogen during infection as a central pathogenic strategy.
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Affiliation(s)
- Erin J. van Schaik
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M UniversityBryan, TX, USA
| | - Elizabeth D. Case
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M UniversityBryan, TX, USA
| | - Eric Martinez
- Centre National de la Recherche Scientifique, Formation de Recherche en Évolution 3689, Centre d'études d'agents Pathogènes et Biotechnologies Pour la Santé, Université MontpellierMontpellier, France
| | - Matteo Bonazzi
- Centre National de la Recherche Scientifique, Formation de Recherche en Évolution 3689, Centre d'études d'agents Pathogènes et Biotechnologies Pour la Santé, Université MontpellierMontpellier, France
| | - James E. Samuel
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M UniversityBryan, TX, USA
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The Effector Cig57 Hijacks FCHO-Mediated Vesicular Trafficking to Facilitate Intracellular Replication of Coxiella burnetii. PLoS Pathog 2016; 12:e1006101. [PMID: 28002452 PMCID: PMC5176192 DOI: 10.1371/journal.ppat.1006101] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2016] [Accepted: 11/29/2016] [Indexed: 02/05/2023] Open
Abstract
Coxiella burnetii is an intracellular bacterial pathogen that infects alveolar macrophages and replicates within a unique lysosome-derived vacuole. When Coxiella is trafficked to a host cell lysosome the essential Dot/Icm type IV secretion system is activated allowing over 130 bacterial effector proteins to be translocated into the host cytosol. This cohort of effectors is believed to manipulate host cell functions to facilitate Coxiella-containing vacuole (CCV) biogenesis and bacterial replication. Transposon mutagenesis has demonstrated that the Dot/Icm effector Cig57 is required for CCV development and intracellular replication of Coxiella. Here, we demonstrate a role for Cig57 in subverting clathrin-mediated traffic through its interaction with FCHO2, an accessory protein of clathrin coated pits. A yeast two-hybrid screen identified FCHO2 as a binding partner of Cig57 and this interaction was confirmed during infection using immunoprecipitation experiments. The interaction between Cig57 and FCHO2 is dependent on one of three endocytic sorting motif encoded by Cig57. Importantly, complementation analysis demonstrated that this endocytic sorting motif is required for full function of Cig57. Consistent with the intracellular growth defect in cig57-disrupted Coxiella, siRNA gene silencing of FCHO2 or clathrin (CLTC) inhibits Coxiella growth and CCV biogenesis. Clathrin is recruited to the replicative CCV in a manner that is dependent on the interaction between Cig57 and FCHO2. Creation of an FCHO2 knockout cell line confirmed the importance of this protein for CCV expansion, intracellular replication of Coxiella and clathrin recruitment to the CCV. Collectively, these results reveal Cig57 to be a significant virulence factor that co-opts clathrin-mediated trafficking, via interaction with FCHO2, to facilitate the biogenesis of the fusogenic Coxiella replicative vacuole and enable intracellular success of this human pathogen. Human Q fever is caused by the intracellular bacterium Coxiella burnetii. Successful infection of human cells relies on a Dot/Icm secretion system and the translocation of effector proteins into the host cell cytosol. The functions of many Coxiella effector proteins, and their contribution to bacterial growth and host manipulation, remain unknown. We show that a unique effector, Cig57, has an important role in manipulation of host cellular clathrin-mediated trafficking. In particular, Cig57 binds FCHO2, a protein involved in formation of clathrin-coated vesicles, in a manner that is dependent on a tyrosine-based endocytic sorting motif. Through engaging proteins in the clathrin pathway, Cig57 facilitates expansion of the Coxiella replicative vacuole and enables the pathogen to replicate to large numbers. Thus, we identify a relationship between a host process and a key virulence protein that are required for pathogen success.
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Mahapatra S, Gallaher B, Smith SC, Graham JG, Voth DE, Shaw EI. Coxiella burnetii Employs the Dot/Icm Type IV Secretion System to Modulate Host NF-κB/RelA Activation. Front Cell Infect Microbiol 2016; 6:188. [PMID: 28066723 PMCID: PMC5165255 DOI: 10.3389/fcimb.2016.00188] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2016] [Accepted: 12/02/2016] [Indexed: 12/17/2022] Open
Abstract
Coxiella burnetii is the causative agent of Q fever and an obligate intracellular pathogen in nature that survives and grows in a parasitophorous vacuole (PV) within eukaryotic host cells. C. burnetii promotes intracellular survival by subverting apoptotic and pro-inflammatory signaling pathways that are typically regulated by nuclear transcription factor-κB (NF-κB). We and others have demonstrated that C. burnetii NMII proteins inhibit expression of pro-inflammatory cytokines and induce expression of anti-apoptotic genes during infection. Here, we demonstrate that C. burnetii promotes intracellular survival by modulating NF-κB subunit p65 (RelA) phosphorylation, and thus activation, in a Type Four B Secretion System (T4BSS)-dependent manner. Immunoblot analysis of RelA phosphorylated at serine-536 demonstrated that C. burnetii increases NF-κB activation via the canonical pathway. However, RelA phosphorylation levels were even higher in infected cells where bacterial protein or mRNA synthesis was inhibited. Importantly, we demonstrate that inhibition of RelA phosphorylation impairs PV formation and C. burnetii growth. We found that a T4BSS-defective mutant (CbΔdotA) elicited phosphorylated RelA levels similar to those of wild type C. burnetii infection treated with Chloramphenicol. Moreover, cells infected with CbΔdotA or wild type C. burnetii treated with Chloramphenicol showed similar levels of GFP-RelA nuclear localization, and significantly increased localization compared to wild type C. burnetii infection. These data indicate that without de novo protein synthesis and a functional T4BSS, C. burnetii is unable to modulate NF-κB activation, which is crucial for optimal intracellular growth.
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Affiliation(s)
- Saugata Mahapatra
- Department of Microbiology and Molecular genetics, Oklahoma State UniversityStillwater, OK, USA
| | - Brandi Gallaher
- Department of Microbiology and Molecular genetics, Oklahoma State UniversityStillwater, OK, USA
| | - Sydni Caet Smith
- Department of Microbiology and Molecular genetics, Oklahoma State UniversityStillwater, OK, USA
| | - Joseph G. Graham
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences (UAMS)Little Rock, AR, USA
| | - Daniel E. Voth
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences (UAMS)Little Rock, AR, USA
| | - Edward I. Shaw
- Department of Microbiology and Molecular genetics, Oklahoma State UniversityStillwater, OK, USA
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Abstract
Intracellular bacterial pathogens have evolved to exploit the protected niche provided within the boundaries of a eukaryotic host cell. Upon entering a host cell, some bacteria can evade the adaptive immune response of its host and replicate in a relatively nutrient-rich environment devoid of competition from other host flora. Growth within a host cell is not without their hazards, however. Many pathogens enter their hosts through receptor-mediated endocytosis or phagocytosis, two intracellular trafficking pathways that terminate in a highly degradative organelle, the phagolysosome. This usually deadly compartment is maintained at a low pH and contains degradative enzymes and reactive oxygen species, resulting in an environment to which few bacterial species are adapted. Some intracellular pathogens, such as Shigella, Listeria, Francisella, and Rickettsia, escape the phagosome to replicate within the cytosol of the host cell. Bacteria that remain within a vacuole either alter the trafficking of their initial phagosomal compartment or adapt to survive within the harsh environment it will soon become. In this chapter, we focus on the mechanisms by which different vacuolar pathogens either evade lysosomal fusion, as in the case of Mycobacterium and Chlamydia, or allow interaction with lysosomes to varying degrees, such as Brucella and Coxiella, and their specific adaptations to inhabit a replicative niche.
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Colonne PM, Winchell CG, Graham JG, Onyilagha FI, MacDonald LJ, Doeppler HR, Storz P, Kurten RC, Beare PA, Heinzen RA, Voth DE. Vasodilator-Stimulated Phosphoprotein Activity Is Required for Coxiella burnetii Growth in Human Macrophages. PLoS Pathog 2016; 12:e1005915. [PMID: 27711191 PMCID: PMC5053435 DOI: 10.1371/journal.ppat.1005915] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Accepted: 09/05/2016] [Indexed: 11/18/2022] Open
Abstract
Coxiella burnetii is an intracellular bacterial pathogen that causes human Q fever, an acute flu-like illness that can progress to chronic endocarditis and liver and bone infections. Humans are typically infected by aerosol-mediated transmission, and C. burnetii initially targets alveolar macrophages wherein the pathogen replicates in a phagolysosome-like niche known as the parasitophorous vacuole (PV). C. burnetii manipulates host cAMP-dependent protein kinase (PKA) signaling to promote PV formation, cell survival, and bacterial replication. In this study, we identified the actin regulatory protein vasodilator-stimulated phosphoprotein (VASP) as a PKA substrate that is increasingly phosphorylated at S157 and S239 during C. burnetii infection. Avirulent and virulent C. burnetii triggered increased levels of phosphorylated VASP in macrophage-like THP-1 cells and primary human alveolar macrophages, and this event required the Cα subunit of PKA. VASP phosphorylation also required bacterial protein synthesis and secretion of effector proteins via a type IV secretion system, indicating the pathogen actively triggers prolonged VASP phosphorylation. Optimal PV formation and intracellular bacterial replication required VASP activity, as siRNA-mediated depletion of VASP reduced PV size and bacterial growth. Interestingly, ectopic expression of a phospho-mimetic VASP (S239E) mutant protein prevented optimal PV formation, whereas VASP (S157E) mutant expression had no effect. VASP (S239E) expression also prevented trafficking of bead-containing phagosomes to the PV, indicating proper VASP activity is critical for heterotypic fusion events that control PV expansion in macrophages. Finally, expression of dominant negative VASP (S157A) in C. burnetii-infected cells impaired PV formation, confirming importance of the protein for proper infection. This study provides the first evidence of VASP manipulation by an intravacuolar bacterial pathogen via activation of PKA in human macrophages. Q fever, caused by the intracellular bacterial pathogen Coxiella burnetii, is an aerosol-transmitted infection that can develop into life-threatening chronic infections such as endocarditis. The pathogen preferentially grows within alveolar macrophages in a phagolysosome-like compartment termed the parasitophorous vacuole (PV). C. burnetii actively manipulates host cAMP-dependent protein kinase (PKA) signaling to promote PV formation and cell survival. Identification of bacterial effector proteins that manipulate PKA and downstream target proteins is critical to fully understand pathogen-mediated signaling circuits and develop new therapeutic strategies. Here, we found that PKA controls vasodilator-stimulated phosphoprotein (VASP) activity to promote PV formation and bacterial replication. VASP regulates actin-based motility used by a subset of intracellular bacteria for propulsion through the host cell cytosol and into bystander cells. However, C. burnetii does not use actin-based motility and replicates throughout its life cycle within a membrane bound vacuole. Thus, this study provides the first evidence of VASP manipulation by an intravacuolar bacterial pathogen. Characterization of VASP function in PV formation and identification of additional PKA substrates that promote infection will provide new insight into host-pathogen interactions during Q fever.
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Affiliation(s)
- Punsiri M. Colonne
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
| | - Caylin G. Winchell
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
| | - Joseph G. Graham
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
| | - Frances I. Onyilagha
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
| | - Laura J. MacDonald
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
| | - Heike R. Doeppler
- Department of Cancer Biology, Mayo Clinic, Jacksonville, Florida, United States of America
| | - Peter Storz
- Department of Cancer Biology, Mayo Clinic, Jacksonville, Florida, United States of America
| | - Richard C. Kurten
- Department of Physiology and Biophysics, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
- Arkansas Children’s Hospital Research Institute, Little Rock, Arkansas, United States of America
| | - Paul A. Beare
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
| | - Robert A. Heinzen
- Coxiella Pathogenesis Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
| | - Daniel E. Voth
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, United States of America
- * E-mail:
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