1
|
Wong Z, Ong EBB. Unravelling bacterial virulence factors in yeast: From identification to the elucidation of their mechanisms of action. Arch Microbiol 2024; 206:303. [PMID: 38878203 DOI: 10.1007/s00203-024-04023-2] [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: 04/19/2024] [Revised: 05/21/2024] [Accepted: 05/29/2024] [Indexed: 06/23/2024]
Abstract
Pathogenic bacteria employ virulence factors (VF) to establish infection and cause disease in their host. Yeasts, Saccharomyces cerevisiae and Saccharomyces pombe, are useful model organisms to study the functions of bacterial VFs and their interaction with targeted cellular processes because yeast processes and organelle structures are highly conserved and similar to higher eukaryotes. In this review, we describe the principles and applications of the yeast model for the identification and functional characterisation of bacterial VFs to investigate bacterial pathogenesis. The growth inhibition phenotype caused by the heterologous expression of bacterial VFs in yeast is commonly used to identify candidate VFs. Then, subcellular localisation patterns of bacterial VFs can provide further clues about their target molecules and functions during infection. Yeast knockout and overexpression libraries are also used to investigate VF interactions with conserved eukaryotic cell structures (e.g., cytoskeleton and plasma membrane), and cellular processes (e.g., vesicle trafficking, signalling pathways, and programmed cell death). In addition, the yeast growth inhibition phenotype is also useful for screening new drug leads that target and inhibit bacterial VFs. This review provides an updated overview of new tools, principles and applications to study bacterial VFs in yeast.
Collapse
Affiliation(s)
- ZhenPei Wong
- Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, Penang, 11800 USM, Malaysia
| | - Eugene Boon Beng Ong
- Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, Penang, 11800 USM, Malaysia.
| |
Collapse
|
2
|
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: 0] [Impact Index Per Article: 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.
Collapse
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
| |
Collapse
|
3
|
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.
Collapse
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
| |
Collapse
|
4
|
Steiert B, Icardi CM, Faris R, McCaslin PN, Smith P, Klingelhutz AJ, Yau PM, Weber MM. The Chlamydia trachomatis type III-secreted effector protein CteG induces centrosome amplification through interactions with centrin-2. Proc Natl Acad Sci U S A 2023; 120:e2303487120. [PMID: 37155906 PMCID: PMC10193975 DOI: 10.1073/pnas.2303487120] [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: 03/07/2023] [Accepted: 04/11/2023] [Indexed: 05/10/2023] Open
Abstract
The centrosome is the main microtubule organizing center of the cell and is crucial for mitotic spindle assembly, chromosome segregation, and cell division. Centrosome duplication is tightly controlled, yet several pathogens, most notably oncogenic viruses, perturb this process leading to increased centrosome numbers. Infection by the obligate intracellular bacterium Chlamydia trachomatis (C.t.) correlates with blocked cytokinesis, supernumerary centrosomes, and multipolar spindles; however, the mechanisms behind how C.t. induces these cellular abnormalities remain largely unknown. Here we show that the secreted effector protein, CteG, binds to centrin-2 (CETN2), a key structural component of centrosomes and regulator of centriole duplication. Our data indicate that both CteG and CETN2 are necessary for infection-induced centrosome amplification, in a manner that requires the C-terminus of CteG. Strikingly, CteG is important for in vivo infection and growth in primary cervical cells but is dispensable for growth in immortalized cells, highlighting the importance of this effector protein to chlamydial infection. These findings begin to provide mechanistic insight into how C.t. induces cellular abnormalities during infection, but also indicate that obligate intracellular bacteria may contribute to cellular transformation events. Centrosome amplification mediated by CteG-CETN2 interactions may explain why chlamydial infection leads to an increased risk of cervical or ovarian cancer.
Collapse
Affiliation(s)
- Brianna Steiert
- Department of Microbiology and Immunology, University of Iowa Carver College of Medicine, Iowa City, IA52242
| | - Carolina M. Icardi
- Department of Microbiology and Immunology, University of Iowa Carver College of Medicine, Iowa City, IA52242
| | - Robert Faris
- Department of Microbiology and Immunology, University of Iowa Carver College of Medicine, Iowa City, IA52242
| | - Paige N. McCaslin
- Department of Microbiology and Immunology, University of Iowa Carver College of Medicine, Iowa City, IA52242
| | - Parker Smith
- Department of Microbiology and Immunology, University of Iowa Carver College of Medicine, Iowa City, IA52242
| | - Aloysius J. Klingelhutz
- Department of Microbiology and Immunology, University of Iowa Carver College of Medicine, Iowa City, IA52242
| | - Peter M. Yau
- Carver Biotechnology Center–Protein Sciences Facility, University of Illinois at Urbana–Champaign, Urbana, IL61801
| | - Mary M. Weber
- Department of Microbiology and Immunology, University of Iowa Carver College of Medicine, Iowa City, IA52242
| |
Collapse
|
5
|
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.
Collapse
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)
| |
Collapse
|
6
|
Functional Characterization of Non-Ankyrin Repeat Domains of Orientia tsutsugamushi Ank Effectors Reveals Their Importance for Molecular Pathogenesis. Infect Immun 2022; 90:e0062821. [PMID: 35435726 DOI: 10.1128/iai.00628-21] [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: 11/20/2022] Open
Abstract
Orientia tsutsugamushi is a genetically intractable obligate intracellular bacterium, causes scrub typhus, and has one of the largest known armamentariums of ankyrin repeat-containing effectors (Anks). Most have a C-terminal F-box presumed to interact with the SCF ubiquitin ligase complex primarily based on their ability to bind overexpressed Skp1. Whether all F-box-containing Anks bind endogenous SCF components and the F-box residues essential for such interactions has gone unexplored. Many O. tsutsugamushi Ank F-boxes occur as part of a PRANC (pox protein repeats of ankyrin-C-terminal) domain. Roles of the non-F-box portion of the PRANC and intervening sequence region (ISR) that links the ankyrin repeat and F-box/PRANC domains are unknown. The functional relevance of these effectors' non-ankyrin repeat domains was investigated. The F-box was necessary for Flag-tagged versions of most F-box-containing Anks to precipitate endogenous Skp1, Cul1, and/or Rbx1, while the ISR and PRANC were dispensable. Ank toxicity in yeast was predominantly F-box dependent. Interrogations of Ank1, Ank5, and Ank6 established that L1, P2, E4, I9, and D17 of the F-box consensus are key for binding native SCF components and for Ank1 and Ank6 to inhibit NF-κB. The ISR is also essential for Ank1 and Ank6 to impair NF-κB. Ectopically expressed Ank1 and Ank6 lacking the ISR or having a mutagenized F-box incapable of binding SCF components performed as dominant-negative inhibitors to block O. tsutsugamushi NF-κB modulation. This study advances knowledge of O. tsutsugamushi Ank functional domains and offers an approach for validating their roles in infection.
Collapse
|
7
|
The type three secretion system effector protein IpgB1 promotes Shigella flexneri cell-to-cell spread through double-membrane vacuole escape. PLoS Pathog 2022; 18:e1010380. [PMID: 35202448 PMCID: PMC8903249 DOI: 10.1371/journal.ppat.1010380] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 03/08/2022] [Accepted: 02/18/2022] [Indexed: 12/11/2022] Open
Abstract
S. flexneri is an important human pathogen that causes bacillary dysentery. During infection, S. flexneri invades colonic epithelial cells, hijacks the host cell cytoskeleton to move in the cytosol of infected cells, and spreads from cell to cell through formation of membrane protrusions that project into adjacent cells and resolve into double membrane vacuoles (DMVs). S. flexneri cell-to-cell spread requires the integrity of the bacterial type three secretion system (T3SS). However, the exact role of the T3SS effector proteins in the dissemination process remains poorly understood. Here, we investigated the role of the T3SS effector protein IpgB1 in S. flexneri dissemination. IpgB1 was previously characterized as a guanine nucleotide exchange factor (GEF) that contributes to invasion. In addition to the invasion defect, we showed that the ipgB1 mutant formed smaller infection foci in HT-29 cells. Complementation of this phenotype required the GEF activity of IpgB1. Using live confocal microscopy, we showed that the ipgB1 mutant is specifically impaired in DMV escape. Depletion of Rac1, the host cell target of IpgB1 during invasion, as well as pharmacological inhibition of Rac1 signaling, reduced cell-to-cell spread and DMV escape. In a targeted siRNA screen, we uncovered that RhoA depletion restored ipgB1 cell-to-cell spread and DMV escape, revealing a critical role for the IpgB1-Rac1 axis in antagonizing RhoA-mediated restriction of DMV escape. Using an infant rabbit model of shigellosis, we showed that the ipgB1 mutant formed fewer and smaller infection foci in the colon of infected animals, which correlated with attenuated symptoms of disease, including epithelial fenestration and bloody diarrhea. Our results demonstrate that, in addition to its role during invasion, IpgB1 modulates Rho family small GTPase signaling to promote cell-to-cell spread, DMV escape, and S. flexneri pathogenesis.
Collapse
|
8
|
Guzman RM, Howard ZP, Liu Z, Oliveira RD, Massa AT, Omsland A, White SN, Goodman AG. Natural genetic variation in Drosophila melanogaster reveals genes associated with Coxiella burnetii infection. Genetics 2021; 217:6117219. [PMID: 33789347 PMCID: PMC8045698 DOI: 10.1093/genetics/iyab005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 01/07/2021] [Indexed: 12/16/2022] Open
Abstract
The gram-negative bacterium Coxiella burnetii is the causative agent of Query (Q) fever in humans and coxiellosis in livestock. Host genetics are associated with C. burnetii pathogenesis both in humans and animals; however, it remains unknown if specific genes are associated with severity of infection. We employed the Drosophila Genetics Reference Panel to perform a genome-wide association study to identify host genetic variants that affect host survival to C. burnetii infection. The genome-wide association study identified 64 unique variants (P < 10−5) associated with 25 candidate genes. We examined the role each candidate gene contributes to host survival during C. burnetii infection using flies carrying a null mutation or RNAi knockdown of each candidate. We validated 15 of the 25 candidate genes using at least one method. This is the first report establishing involvement of many of these genes or their homologs with C. burnetii susceptibility in any system. Among the validated genes, FER and tara play roles in the JAK/STAT, JNK, and decapentaplegic/TGF-β signaling pathways which are components of known innate immune responses to C. burnetii infection. CG42673 and DIP-ε play roles in bacterial infection and synaptic signaling but have no previous association with C. burnetii pathogenesis. Furthermore, since the mammalian ortholog of CG13404 (PLGRKT) is an important regulator of macrophage function, CG13404 could play a role in host susceptibility to C. burnetii through hemocyte regulation. These insights provide a foundation for further investigation regarding the genetics of C. burnetii susceptibility across a wide variety of hosts.
Collapse
Affiliation(s)
- Rosa M Guzman
- School of Molecular Biosciences, College of Veterinary Medicine, Washington State University, Pullman, WA 99164, USA
| | - Zachary P Howard
- School of Molecular Biosciences, College of Veterinary Medicine, Washington State University, Pullman, WA 99164, USA
| | - Ziying Liu
- School of Molecular Biosciences, College of Veterinary Medicine, Washington State University, Pullman, WA 99164, USA
| | - Ryan D Oliveira
- Department of Veterinary Microbiology and Pathology, College of Veterinary Medicine, Washington State University, Pullman, WA 99164, USA
| | - Alisha T Massa
- Department of Veterinary Microbiology and Pathology, College of Veterinary Medicine, Washington State University, Pullman, WA 99164, USA
| | - Anders Omsland
- Paul G. Allen School for Global Animal Health, College of Veterinary Medicine, Washington State University, Pullman, WA 99164, USA
| | - Stephen N White
- Department of Veterinary Microbiology and Pathology, College of Veterinary Medicine, Washington State University, Pullman, WA 99164, USA.,USDA-ARS Animal Disease Research, Pullman, WA 99164, USA.,Center for Reproductive Biology, Washington State University, Pullman, WA 99164, USA
| | - Alan G Goodman
- School of Molecular Biosciences, College of Veterinary Medicine, Washington State University, Pullman, WA 99164, USA.,Paul G. Allen School for Global Animal Health, College of Veterinary Medicine, Washington State University, Pullman, WA 99164, USA
| |
Collapse
|
9
|
Kovacs-Simon A, Metters G, Norville I, Hemsley C, Titball RW. Coxiella burnetii replicates in Galleria mellonella hemocytes and transcriptome mapping reveals in vivo regulated genes. Virulence 2021; 11:1268-1278. [PMID: 32970966 PMCID: PMC7549970 DOI: 10.1080/21505594.2020.1819111] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Larvae of the greater wax moth (Galleria mellonella) are susceptible to infection with C. burnetii, an obligate intracellular bacterial pathogen. We show that bacteria are found in hemocytes after infection, and occupy vacuoles which are morphologically similar to Coxiella-containing vacuoles seen in infected mammalian phagocytes. We characterized the infection by transcriptome profiling of bacteria isolated from the hemocytes of infected larvae and identified 46 highly upregulated genes. The encoded proteins are predicted to be involved in translation, LPS biosynthesis, biotin synthesis, scavenging of reactive oxygen species, and included a T4SS effector and 30 hypothetical proteins. Some of these genes had previously been shown to be upregulated in buffalo green monkey (BGM) cells or in mice, whilst others appear to be regulated in a host-specific manner. Altogether, our results demonstrate the value of the G. mellonella model to study intracellular growth and identify potential virulence factors of C. burnetii.
Collapse
Affiliation(s)
- Andrea Kovacs-Simon
- College of Life and Environmental Sciences - Biosciences, University of Exeter , Exeter, UK
| | - Georgie Metters
- College of Life and Environmental Sciences - Biosciences, University of Exeter , Exeter, UK
| | - Isobel Norville
- CBR Division, Defence Science and Technology Laboratory , Porton Down,Salisbury, UK
| | - Claudia Hemsley
- College of Life and Environmental Sciences - Biosciences, University of Exeter , Exeter, UK
| | - Richard W Titball
- College of Life and Environmental Sciences - Biosciences, University of Exeter , Exeter, UK
| |
Collapse
|
10
|
Steiner S, Meir A, Roy CR. Coxiella burnetii encodes an LvgA-related protein important for intracellular replication. Cell Microbiol 2021; 23:e13331. [PMID: 33774901 DOI: 10.1111/cmi.13331] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 03/05/2021] [Accepted: 03/23/2021] [Indexed: 12/29/2022]
Abstract
Coxiella burnetii is a bacterial pathogen that replicates in a specialised lysosome-derived organelle called the Coxiella-containing vacuole (CCV). Establishment of the CCV requires the Dot/Icm type IVB secretion system. A previous transposon mutagenesis screen identified the gene cbu1754 as being important for the intracellular replication of C. burnetii. To understand the function of the protein encoded by cbu1754, CCV maturation and intracellular replication phenotypes of a cbu1754 mutant were analysed. In contrast to vacuoles containing wild-type C. burnetii Nine Mile phase II, vacuoles containing the isogenic cbu1754 mutant were smaller and did not display detectible amounts of the autophagy protein LC3, which indicated a CCV biogenesis defect. The Cbu1754 protein was not efficiently delivered into the host cell cytosol during infection, which indicated this protein is not a Dot/Icm-translocated effector protein. Secondary structure predictions suggested that Cbu1754 could be similar to the Legionella pneumophila LvgA protein, which is a component of the Dot/Icm apparatus. Consistent with this hypothesis, production of Cbu1754 in an L. pneumophila ∆lvgA mutant restored LvgA-dependent activities. The L. pneumophila proteins LvgA, IcmS and IcmW are interacting partners that comprise a subassembly of the coupling protein complex that mediates Dot/Icm-dependent effector translocation. Similarly, the Cbu1754 protein was found to be a component of the chaperone complex containing the C. burnetii proteins IcmS and IcmW. Thus, the Cbu1754 protein is an LvgA-related protein important for Dot/Icm function and intracellular replication of C. burnetii.
Collapse
Affiliation(s)
- Samuel Steiner
- Department of Microbial Pathogenesis, Yale University School of Medicine, New Haven, Connecticut, USA
| | - Amit Meir
- 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
| |
Collapse
|
11
|
Friedrich A, Beare PA, Schulze-Luehrmann J, Cordsmeier A, Pazen T, Sonnewald S, Lührmann A. The Coxiella burnetii effector protein CaeB modulates endoplasmatic reticulum (ER) stress signalling and is required for efficient replication in Galleria mellonella. Cell Microbiol 2021; 23:e13305. [PMID: 33355405 DOI: 10.1111/cmi.13305] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 12/15/2020] [Accepted: 12/20/2020] [Indexed: 01/02/2023]
Abstract
The obligate intracellular pathogen Coxiella burnetii is the causative agent of the zoonosis Q fever. C. burnetii infection can have severe outcomes due to the development of chronic infection. To establish and maintain an infection, C. burnetii depends on a functional type IVB secretion system (T4BSS) and, thus, on the translocation of effector proteins into the host cell. Here, we showed that the C. burnetii T4BSS effector protein CaeB targets the conserved endoplasmatic reticulum (ER) stress sensor IRE1 during ER stress in mammalian and plant cells. CaeB-induced upregulation of IRE1 RNase activity was essential for CaeB-mediated inhibition of ER stress-induced cell death. Our data reveal a novel role for CaeB in ER stress signalling modulation and demonstrate that CaeB is involved in pathogenicity in vivo. Furthermore, we provide evidence that C. burnetii infection leads to modulation of the ER stress sensors IRE1 and PERK, but not ATF6 during ER stress. While the upregulation of the RNase activity of IRE1 during ER stress depends on CaeB, modulation of PERK is CaeB independent, suggesting that C. burnetii encodes several factors influencing ER stress during infection.
Collapse
Affiliation(s)
- Anja Friedrich
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany.,Lehrstuhl für Biochemie, 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, USA
| | - Jan Schulze-Luehrmann
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Arne Cordsmeier
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Tobias Pazen
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Sophia Sonnewald
- Lehrstuhl für Biochemie, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany
| | - Anja Lührmann
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany
| |
Collapse
|
12
|
Schäfer W, Schmidt T, Cordsmeier A, Borges V, Beare PA, Pechstein J, Schulze-Luehrmann J, Holzinger J, Wagner N, Berens C, Heydel C, Gomes JP, Lührmann A. The anti-apoptotic Coxiella burnetii effector protein AnkG is a strain specific virulence factor. Sci Rep 2020; 10:15396. [PMID: 32958854 PMCID: PMC7506536 DOI: 10.1038/s41598-020-72340-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Accepted: 08/26/2020] [Indexed: 11/24/2022] Open
Abstract
The ability to inhibit host cell apoptosis is important for the intracellular replication of the obligate intracellular pathogen Coxiella burnetii, as it allows the completion of the lengthy bacterial replication cycle. Effector proteins injected into the host cell by the C. burnetii type IVB secretion system (T4BSS) are required for the inhibition of host cell apoptosis. AnkG is one of these anti-apoptotic effector proteins. The inhibitory effect of AnkG requires its nuclear localization, which depends on p32-dependent intracellular trafficking and importin-α1-mediated nuclear entry of AnkG. Here, we compared the sequences of ankG from 37 C. burnetii isolates and classified them in three groups based on the predicted protein size. The comparison of the three different groups allowed us to identify the first 28 amino acids as essential and sufficient for the anti-apoptotic activity of AnkG. Importantly, only the full-length protein from the first group is a bona fide effector protein injected into host cells during infection and has anti-apoptotic activity. Finally, using the Galleria mellonella infection model, we observed that AnkG from the first group has the ability to attenuate pathology during in vivo infection, as it allows survival of the larvae despite bacterial replication.
Collapse
Affiliation(s)
- Walter Schäfer
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Wasserturmstraße 3/5, 91054, Erlangen, Germany
| | - Teresa Schmidt
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Wasserturmstraße 3/5, 91054, Erlangen, Germany
| | - Arne Cordsmeier
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Wasserturmstraße 3/5, 91054, Erlangen, Germany
| | - Vítor Borges
- Department of Infectious Diseases, National Institute of Health, Lisbon, Portugal
| | - 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
| | - Julian Pechstein
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Wasserturmstraße 3/5, 91054, Erlangen, Germany
| | - Jan Schulze-Luehrmann
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Wasserturmstraße 3/5, 91054, Erlangen, Germany
| | - Jonas Holzinger
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Wasserturmstraße 3/5, 91054, Erlangen, Germany
| | - Nicole Wagner
- Institut für Molekulare Pathogenese, Friedrich-Loeffler-Institut, 07743, Jena, Germany
| | - Christian Berens
- Institut für Molekulare Pathogenese, Friedrich-Loeffler-Institut, 07743, Jena, Germany
| | - Carsten Heydel
- Institut für Hygiene und Infektionskrankheiten der Tiere, Justus Liebig Universität Gießen, Frankfurter Straße 85-89, 35392, Gießen, Germany
| | - João Paulo Gomes
- Department of Infectious Diseases, National Institute of Health, Lisbon, Portugal
| | - Anja Lührmann
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Wasserturmstraße 3/5, 91054, Erlangen, Germany.
| |
Collapse
|
13
|
Faris R, McCullough A, Andersen SE, Moninger TO, Weber MM. The Chlamydia trachomatis secreted effector TmeA hijacks the N-WASP-ARP2/3 actin remodeling axis to facilitate cellular invasion. PLoS Pathog 2020; 16:e1008878. [PMID: 32946535 PMCID: PMC7526919 DOI: 10.1371/journal.ppat.1008878] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Revised: 09/30/2020] [Accepted: 08/12/2020] [Indexed: 11/19/2022] Open
Abstract
As an obligate intracellular pathogen, host cell invasion is paramount to Chlamydia trachomatis proliferation. While the mechanistic underpinnings of this essential process remain ill-defined, it is predicted to involve delivery of prepackaged effector proteins into the host cell that trigger plasma membrane remodeling and cytoskeletal reorganization. The secreted effector proteins TmeA and TarP, have risen to prominence as putative key regulators of cellular invasion and bacterial pathogenesis. Although several studies have begun to unravel molecular details underlying the putative function of TarP, the physiological function of TmeA during host cell invasion is unknown. Here, we show that TmeA employs molecular mimicry to bind to the GTPase binding domain of N-WASP, which results in recruitment of the actin branching ARP2/3 complex to the site of chlamydial entry. Electron microscopy revealed that TmeA mutants are deficient in filopodia capture, suggesting that TmeA/N-WASP interactions ultimately modulate host cell plasma membrane remodeling events necessary for chlamydial entry. Importantly, while both TmeA and TarP are necessary for effective host cell invasion, we show that these effectors target distinct pathways that ultimately converge on activation of the ARP2/3 complex. In line with this observation, we show that a double mutant suffers from a severe entry defect nearly identical to that observed when ARP3 is chemically inhibited or knocked down. Collectively, our study highlights both TmeA and TarP as essential regulators of chlamydial invasion that modulate the ARP2/3 complex through distinct signaling platforms, resulting in plasma membrane remodeling events that are essential for pathogen uptake.
Collapse
Affiliation(s)
- Robert Faris
- Department of Microbiology and Immunology, University of Iowa Carver College of Medicine, Iowa City, Iowa, United States of America
| | - Alix McCullough
- Department of Microbiology and Immunology, University of Iowa Carver College of Medicine, Iowa City, Iowa, United States of America
| | - Shelby E. Andersen
- Department of Microbiology and Immunology, University of Iowa Carver College of Medicine, Iowa City, Iowa, United States of America
| | - Thomas O. Moninger
- Central Microscopy Research Facility, University of Iowa Carver College of Medicine, Iowa City, Iowa, United States of America
| | - Mary M. Weber
- Department of Microbiology and Immunology, University of Iowa Carver College of Medicine, Iowa City, Iowa, United States of America
| |
Collapse
|
14
|
Faris R, Merling M, Andersen SE, Dooley CA, Hackstadt T, Weber MM. Chlamydia trachomatis CT229 Subverts Rab GTPase-Dependent CCV Trafficking Pathways to Promote Chlamydial Infection. Cell Rep 2020; 26:3380-3390.e5. [PMID: 30893609 DOI: 10.1016/j.celrep.2019.02.079] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Revised: 11/28/2018] [Accepted: 02/20/2019] [Indexed: 01/25/2023] Open
Abstract
Chlamydial infection requires the formation of a membrane-bound vacuole, termed the inclusion, that undergoes extensive interactions with select host organelles. The importance of the Inc protein CT229 in the formation and maintenance of the chlamydial inclusion was recently highlighted by studies demonstrating that its absence during infection results in reduced bacterial replication, premature inclusion lysis, and host cell death. Previous reports have indicated that CT229 binds Rab GTPases; however, the physiological implications of this interaction are unknown. Here, we show that CT229 regulates host multivesicular trafficking by recruiting multiple Rab GTPases and their cognate effectors to the inclusion. We demonstrate that CT229 specifically modulates clathrin-coated vesicle trafficking and regulates the trafficking of transferrin and the mannose-6-phosphate receptor, both of which are crucial for proper chlamydial development. This study highlights CT229 as a master regulator of multiple host vesicular trafficking pathways essential for chlamydial infection.
Collapse
Affiliation(s)
- Robert Faris
- Department of Microbiology and Immunology, University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA
| | - Marlena Merling
- Department of Microbiology and Immunology, University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA; Department of Biology, University of Dayton, Dayton, OH 45469, USA
| | - Shelby E Andersen
- Department of Microbiology and Immunology, University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA
| | - Cheryl A Dooley
- Host Parasite Interactions Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institutes of Allergy and Infectious Disease, NIH, Hamilton, MT 59840, USA
| | - Ted Hackstadt
- Host Parasite Interactions Section, Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institutes of Allergy and Infectious Disease, NIH, Hamilton, MT 59840, USA
| | - Mary M Weber
- Department of Microbiology and Immunology, University of Iowa Carver College of Medicine, Iowa City, IA 52242, USA.
| |
Collapse
|
15
|
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: 24] [Impact Index Per Article: 6.0] [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.
Collapse
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.
| |
Collapse
|
16
|
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.
Collapse
|
17
|
Metters G, Norville IH, Titball RW, Hemsley CM. From cell culture to cynomolgus macaque: infection models show lineage-specific virulence potential of Coxiella burnetii. J Med Microbiol 2019; 68:1419-1430. [PMID: 31424378 DOI: 10.1099/jmm.0.001064] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Coxiella burnetii is an obligate intracellular pathogen that causes the zoonotic disease Q fever in humans, which can occur in either an acute or a chronic form with serious complications. The bacterium has a wide host range, including unicellular organisms, invertebrates, birds and mammals, with livestock representing the most significant reservoir for human infections. Cell culture models have been used to decipher the intracellular lifestyle of C. burnetii, and several infection models, including invertebrates, rodents and non-human primates, are being used to investigate host-pathogen interactions and to identify bacterial virulence factors and vaccine candidates. However, none of the models replicate all aspects of human disease. Furthermore, it is becoming evident that C. burnetii isolates belonging to different lineages exhibit differences in their virulence in these models. Here, we compare the advantages and disadvantages of commonly used infection models and summarize currently available data for lineage-specific virulence.
Collapse
Affiliation(s)
- Georgina Metters
- College of Life and Environmental Sciences - Biosciences, University of Exeter, Exeter, UK
| | - Isobel H Norville
- Defence Science and Technology Laboratory, Porton Down, Salisbury, UK
| | - Richard W Titball
- College of Life and Environmental Sciences - Biosciences, University of Exeter, Exeter, UK
| | - Claudia M Hemsley
- College of Life and Environmental Sciences - Biosciences, University of Exeter, Exeter, UK
| |
Collapse
|
18
|
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.
Collapse
Affiliation(s)
- Eric Martinez
- IRIM, University of Montpellier, CNRS, 34293 Montpellier, France
| | | | - Matteo Bonazzi
- IRIM, University of Montpellier, CNRS, 34293 Montpellier, France
| |
Collapse
|
19
|
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.
Collapse
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
| |
Collapse
|
20
|
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.
Collapse
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.
| |
Collapse
|
21
|
Pechstein J, Schulze-Luehrmann J, Lührmann A. Coxiella burnetii as a useful tool to investigate bacteria-friendly host cell compartments. Int J Med Microbiol 2017; 308:77-83. [PMID: 28935173 DOI: 10.1016/j.ijmm.2017.09.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Revised: 08/21/2017] [Accepted: 09/11/2017] [Indexed: 10/25/2022] Open
Abstract
Coxiella burnetii is an obligate intracellular and airborne pathogen which can cause the zoonotic disease Q fever. After inhalation of contaminated aerosols alveolar macrophages are taking up C. burnetii into a phagosome. This phagosome matures to a very large vacuole called the C. burnetii-containing vacuole (CCV). Host endogenous and bacterial driven processes lead to the biogenesis of this unusual compartment, which resembles partially a phagolysosome. However, there are several important differences to the classical phagolysosome, which are crucial for the ability of C. burnetii to replicate intracellularly and depend on a functional type IV secretion system (T4SS). The T4SS delivers effector proteins into the host cell cytoplasm to redirect intracellular processes, leading to the establishment of a microenvironment allowing bacterial replication. This article summarizes the current knowledge of the microenvironment permissive for C. burnetii replication.
Collapse
Affiliation(s)
- Julian Pechstein
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Wasserturmstraße 3/5, D-91054 Erlangen, Germany
| | - Jan Schulze-Luehrmann
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Wasserturmstraße 3/5, D-91054 Erlangen, Germany
| | - Anja Lührmann
- Mikrobiologisches Institut - Klinische Mikrobiologie, Immunologie und Hygiene, Universitätsklinikum Erlangen, Friedrich-Alexander-Universität Erlangen-Nürnberg, Wasserturmstraße 3/5, D-91054 Erlangen, Germany.
| |
Collapse
|
22
|
|
23
|
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.
Collapse
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
| |
Collapse
|