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Pha K, Mirrashidi K, Sherry J, Tran CJ, Herrera CM, McMahon E, Elwell CA, Engel JN. The Chlamydia effector IncE employs two short linear motifs to reprogram host vesicle trafficking. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.23.590830. [PMID: 38712241 PMCID: PMC11071397 DOI: 10.1101/2024.04.23.590830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2024]
Abstract
Chlamydia trachomatis, a leading cause of bacteria sexually transmitted infections, creates a specialized intracellular replicative niche by translocation and insertion of a diverse array of effectors (Incs) into the inclusion membrane. Here, we characterize IncE, a multi-functional Inc that encodes two non-overlapping short linear motifs (SLiMs) within its short cytosolic C-terminus. The proximal SLiM mimics an R-SNARE motif to recruit syntaxin (STX) 7 and 12-containing vesicles to the inclusion. The distal SLiM mimics the Sorting Nexin (SNX) 5 and 6 cargo binding site to recruit SNX6-containing vesicles to the inclusion. By simultaneously binding to two distinct vesicle classes, IncE reprograms host cell trafficking to promote the formation of a class of hybrid vesicles at the inclusion that are required for C. trachomatis intracellular development. Our work suggests that Incs may have evolved SLiMs to facilitate rapid evolution in a limited protein space to disrupt host cell processes.
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Herrera CM, McMahon E, Swaney DL, Sherry J, Pha K, Adams-Boone K, Johnson JR, Krogan NJ, Stevers M, Solomon D, Elwell C, Engel J. The Chlamydia trachomatis Inc Tri1 interacts with TRAF7 to displace native TRAF7 interacting partners. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.26.581999. [PMID: 38464023 PMCID: PMC10925117 DOI: 10.1101/2024.02.26.581999] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
Chlamydia trachomatis is the leading cause of bacterial sexually transmitted infections in the US and of preventable blindness worldwide. This obligate intracellular pathogen replicates within a membrane-bound inclusion, but how it acquires nutrients from the host while avoiding detection by the innate immune system is incompletely understood. C. trachomatis accomplishes this in part through the translocation of a unique set of effectors into the inclusion membrane, the inc lusion membrane proteins (Incs). Incs are ideally positioned at the host-pathogen interface to reprogram host signaling by redirecting proteins or organelles to the inclusion. Using a combination of co-affinity purification, immunofluorescence confocal imaging, and proteomics, we characterize the interaction between an early-expressed Inc of unknown function, Tri1, and tumor necrosis factor receptor associated factor 7 (TRAF7). TRAF7 is a multi-domain protein with a RING finger ubiquitin ligase domain and a C-terminal WD40 domain. TRAF7 regulates several innate immune signaling pathways associated with C. trachomatis infection and is mutated in a subset of tumors. We demonstrate that Tri1 and TRAF7 specifically interact during infection and that TRAF7 is recruited to the inclusion. We further show that the predicted coiled-coil domain of Tri1 is necessary to interact with the TRAF7 WD40 domain. Finally, we demonstrate that Tri1 displaces the native TRAF7 binding partners, mitogen activated protein kinase kinase kinase 2 (MEKK2) and MEKK3. Together, our results suggest that by displacing TRAF7 native binding partners, Tri1 has the capacity to alter TRAF7 signaling during C. trachomatis infection. Importance Chlamydia trachomatis is the leading cause of bacterial sexually transmitted infections in the US and preventable blindness worldwide. Although easily treated with antibiotics, the vast majority of infections are asymptomatic and therefore go untreated, leading to infertility and blindness. This obligate intracellular pathogen evades the immune response, which contributes to these outcomes. Here, we characterize the interaction between a C. trachomatis secreted effector, Tri1, and a host protein involved in innate immune signaling, TRAF7. We identified host proteins that bind to TRAF7 and demonstrate that Tri1 can displace these proteins upon binding to TRAF7. Remarkably, the region of TRAF7 to which these host proteins bind is often mutated in a subset of human tumors. Our work suggests a mechanism by which Tri1 may alter TRAF7 signaling and has implications not only in the pathogenesis of C. trachomatis infections, but also in understanding the role of TRAF7 in cancer.
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Bastidas RJ, Kędzior M, Davidson RK, Walsh SC, Dolat L, Sixt BS, Pruneda JN, Coers J, Valdivia RH. The acetylase activity of Cdu1 regulates bacterial exit from infected cells by protecting Chlamydia effectors from degradation. eLife 2024; 12:RP87386. [PMID: 38358795 PMCID: PMC10942603 DOI: 10.7554/elife.87386] [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] [Indexed: 02/16/2024] Open
Abstract
Many cellular processes are regulated by ubiquitin-mediated proteasomal degradation. Pathogens can regulate eukaryotic proteolysis through the delivery of proteins with de-ubiquitinating (DUB) activities. The obligate intracellular pathogen Chlamydia trachomatis secretes Cdu1 (ChlaDUB1), a dual deubiquitinase and Lys-acetyltransferase, that promotes Golgi remodeling and survival of infected host cells presumably by regulating the ubiquitination of host and bacterial proteins. Here, we determined that Cdu1's acetylase but not its DUB activity is important to protect Cdu1 from ubiquitin-mediated degradation. We further identified three C. trachomatis proteins on the pathogen-containing vacuole (InaC, IpaM, and CTL0480) that required Cdu1's acetylase activity for protection from degradation and determined that Cdu1 and these Cdu1-protected proteins are required for optimal egress of Chlamydia from host cells. These findings highlight a non-canonical mechanism of pathogen-mediated protection of virulence factors from degradation after their delivery into host cells and the coordinated regulation of secreted effector proteins.
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Affiliation(s)
- Robert J Bastidas
- Department of Integrative Immunobiology, Duke UniversityDurhamUnited States
| | - Mateusz Kędzior
- Department of Integrative Immunobiology, Duke UniversityDurhamUnited States
| | - Robert K Davidson
- Department of Molecular Genetics and Microbiology, Duke UniversityDukeUnited States
| | - Stephen C Walsh
- Department of Molecular Genetics and Microbiology, Duke UniversityDukeUnited States
| | - Lee Dolat
- Department of Integrative Immunobiology, Duke UniversityDurhamUnited States
| | - Barbara S Sixt
- Deparment of Molecular Biology, Umeå UniversityUmeåSweden
- The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå UniversityUmeåSweden
- Umeå Centre for Microbial Research (UCMR), Umeå UniversityUmeåSweden
| | - Jonathan N Pruneda
- Department of Molecular Microbiology & Immunology, Oregon Health & Science UniversityPortlandUnited States
| | - Jorn Coers
- Department of Integrative Immunobiology, Duke UniversityDurhamUnited States
- Department of Molecular Genetics and Microbiology, Duke UniversityDukeUnited States
| | - Raphael H Valdivia
- Department of Integrative Immunobiology, Duke UniversityDurhamUnited States
- Department of Molecular Genetics and Microbiology, Duke UniversityDukeUnited States
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Fernandez CM, Krockenberger MB, Crowther MS, Mella VSA, Wilmott L, Higgins DP. Genetic markers of Chlamydia pecorum virulence in ruminants support short term host-pathogen evolutionary relationships in the koala, Phascolarctos cinereus. INFECTION, GENETICS AND EVOLUTION : JOURNAL OF MOLECULAR EPIDEMIOLOGY AND EVOLUTIONARY GENETICS IN INFECTIOUS DISEASES 2023; 116:105527. [PMID: 37977420 DOI: 10.1016/j.meegid.2023.105527] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2023] [Revised: 11/05/2023] [Accepted: 11/14/2023] [Indexed: 11/19/2023]
Abstract
In ruminants infected with Chlamydia pecorum, shorter lengths of coding tandem repeats (CTR) within two genes, the inclusion membrane protein (incA) and Type III secretor protein (ORF663), have been previously associated with pathogenic outcomes. In other chlamydial species, the presence of a chlamydial plasmid has been linked to heightened virulence, and the plasmid is not ubiquitous in C. pecorum across the koala's range. We therefore investigated these three markers: incA, ORF663 and C. pecorum plasmid, as potential indicators of virulence in two koala populations in New South Wales with differing expression of urogenital chlamydiosis; the Liverpool Plains and one across the Southern Highlands and South-west Sydney (SHSWS). We also investigated the diversity of these loci within strains characterised by the national multi-locus sequence typing (MLST) scheme. Although CTR lengths of incA and ORF663 varied across the populations, they occurred only within previously described pathogenic ranges for ruminants. This suggests a relatively short-term host-pathogen co-evolution within koalas and limits the utility of CTR lengths for incA and ORF663 as virulence markers in the species. However, in contrast to reports of evolution of C. pecorum towards lower virulence, as indicated by longer CTR lengths in ruminants and swine, CTR lengths for ORF663 appeared to be diverging towards less common shorter CTR lengths within strains recently introduced to koalas in the Liverpool Plains. We detected the plasmid across 90% and 92% of samples in the Liverpool Plains and SHSWS respectively, limiting its utility as an indicator of virulence. It would be valuable to examine the CTR lengths of these loci across koala populations nationally. Investigation of other hypervariable loci may elucidate the evolutionary trajectory of virulence in C. pecorum induced disease in koalas. Profiling of virulent strains will be important in risk assessments for strain movement to naïve or susceptible populations through translocations and wildlife corridor construction.
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Affiliation(s)
- Cristina M Fernandez
- Faculty of Science, Sydney School of Veterinary Science, The University of Sydney, Camperdown, Sydney 2006, NSW, Australia
| | - Mark B Krockenberger
- Faculty of Science, Sydney School of Veterinary Science, The University of Sydney, Camperdown, Sydney 2006, NSW, Australia; Sydney Infectious diseases, The University of Sydney, Camperdown, Sydney 2006, NSW, Australia
| | - Mathew S Crowther
- Faculty of Science, School of Life and Environmental Science, The University of Sydney, Sydney 2006, New South Wales, Australia
| | - Valentina S A Mella
- Faculty of Science, Sydney School of Veterinary Science, The University of Sydney, Camperdown, Sydney 2006, NSW, Australia; Faculty of Science, School of Life and Environmental Science, The University of Sydney, Sydney 2006, New South Wales, Australia
| | - Lachlan Wilmott
- NSW Department of Planning and Environment, Wollongong 2005, New South Wales, Australia
| | - Damien P Higgins
- Faculty of Science, Sydney School of Veterinary Science, The University of Sydney, Camperdown, Sydney 2006, NSW, Australia.
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Bastidas RJ, Kędzior M, Davidson RK, Walsh SC, Dolat L, Sixt BS, Pruneda JN, Coers J, Valdivia RH. The acetylase activity of Cdu1 regulates bacterial exit from infected cells by protecting Chlamydia effectors from degradation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.28.530337. [PMID: 36909574 PMCID: PMC10002621 DOI: 10.1101/2023.02.28.530337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
Abstract
Many cellular processes are regulated by ubiquitin-mediated proteasomal degradation. Pathogens can regulate eukaryotic proteolysis through the delivery of proteins with de-ubiquitinating (DUB) activities. The obligate intracellular pathogen Chlamydia trachomatis secretes Cdu1 (ChlaDUB1), a dual deubiquitinase and Lys-acetyltransferase, that promotes Golgi remodeling and survival of infected host cells presumably by regulating the ubiquitination of host and bacterial proteins. Here we determined that Cdu1's acetylase but not its DUB activity is important to protect Cdu1 from ubiquitin-mediated degradation. We further identified three C. trachomatis proteins on the pathogen-containing vacuole (InaC, IpaM, and CTL0480) that required Cdu1's acetylase activity for protection from degradation and determined that Cdu1 and these Cdu1-protected proteins are required for optimal egress of Chlamydia from host cells. These findings highlight a non-canonical mechanism of pathogen-mediated protection of virulence factors from degradation after their delivery into host cells and the coordinated regulation of secreted effector proteins.
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Affiliation(s)
- Robert J. Bastidas
- Department of Integrative Immunobiology, Duke University, Durham, N.C 27708, USA
| | - Mateusz Kędzior
- Department of Integrative Immunobiology, Duke University, Durham, N.C 27708, USA
| | - Robert K. Davidson
- Department of Molecular Genetics and Microbiology, Duke University, Durham, N.C 27708, USA
| | - Stephen C. Walsh
- Department of Molecular Genetics and Microbiology, Duke University, Durham, N.C 27708, USA
| | - Lee Dolat
- Department of Integrative Immunobiology, Duke University, Durham, N.C 27708, USA
| | - Barbara S. Sixt
- Deparment of Molecular Biology, Umeå University, Umeå, Sweden
- The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden
- Umeå Centre for Microbial Research (UCMR), Umeå University, Umeå, Sweden
| | - Jonathan N. Pruneda
- Department of Molecular Microbiology & Immunology, Oregon Health & Science University, Portland, OR 97239, USA
| | - Jörn Coers
- Department of Integrative Immunobiology, Duke University, Durham, N.C 27708, USA
- Department of Molecular Genetics and Microbiology, Duke University, Durham, N.C 27708, USA
| | - Raphael H. Valdivia
- Department of Integrative Immunobiology, Duke University, Durham, N.C 27708, USA
- Department of Molecular Genetics and Microbiology, Duke University, Durham, N.C 27708, USA
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Abstract
Type III secretion systems (T3SSs) are utilized by Gram-negative pathogens to enhance their pathogenesis. This secretion system is associated with the delivery of effectors through a needle-like structure from the bacterial cytosol directly into a target eukaryotic cell. These effector proteins then manipulate specific eukaryotic cell functions to benefit pathogen survival within the host. The obligate intracellular pathogens of the family Chlamydiaceae have a highly evolutionarily conserved nonflagellar T3SS that is an absolute requirement for their survival and propagation within the host with about one-seventh of the genome dedicated to genes associated with the T3SS apparatus, chaperones, and effectors. Chlamydiae also have a unique biphasic developmental cycle where the organism alternates between an infectious elementary body (EB) and replicative reticulate body (RB). T3SS structures have been visualized on both EBs and RBs. And there are effector proteins that function at each stage of the chlamydial developmental cycle, including entry and egress. This review will discuss the history of the discovery of chlamydial T3SS and the biochemical characterization of components of the T3SS apparatus and associated chaperones in the absence of chlamydial genetic tools. These data will be contextualized into how the T3SS apparatus functions throughout the chlamydial developmental cycle and the utility of heterologous/surrogate models to study chlamydial T3SS. Finally, there will be a targeted discussion on the history of chlamydial effectors and recent advances in the field.
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Affiliation(s)
- Elizabeth A. Rucks
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Durham Research Center II, Omaha, Nebraska, USA
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Luís MP, Pereira IS, Bugalhão JN, Simões CN, Mota C, Romão MJ, Mota LJ. The Chlamydia trachomatis IncM Protein Interferes with Host Cell Cytokinesis, Centrosome Positioning, and Golgi Distribution and Contributes to the Stability of the Pathogen-Containing Vacuole. Infect Immun 2023; 91:e0040522. [PMID: 36877064 PMCID: PMC10112248 DOI: 10.1128/iai.00405-22] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2022] [Accepted: 02/13/2023] [Indexed: 03/07/2023] Open
Abstract
Chlamydia trachomatis is an obligate intracellular bacterial pathogen that causes ocular and urogenital infections in humans. The ability of C. trachomatis to grow intracellularly in a pathogen-containing vacuole (known as an inclusion) depends on chlamydial effector proteins transported into the host cell by a type III secretion system. Among these effectors, several inclusion membrane proteins (Incs) insert in the vacuolar membrane. Here, we show that human cell lines infected by a C. trachomatis strain deficient for Inc CT288/CTL0540 (renamed IncM) displayed less multinucleation than when infected by IncM-producing strains (wild type or complemented). This indicated that IncM is involved in the ability of Chlamydia to inhibit host cell cytokinesis. The capacity of IncM to induce multinucleation in infected cells was shown to be conserved among its chlamydial homologues and appeared to require its two larger regions predicted to be exposed to the host cell cytosol. C. trachomatis-infected cells also displayed IncM-dependent defects in centrosome positioning, Golgi distribution around the inclusion, and morphology and stability of the inclusion. The altered morphology of inclusions containing IncM-deficient C. trachomatis was further affected by depolymerization of host cell microtubules. This was not observed after depolymerization of microfilaments, and inclusions containing wild-type C. trachomatis did not alter their morphology upon depolymerization of microtubules. Overall, these findings suggest that IncM may exert its effector function by acting directly or indirectly on host cell microtubules.
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Affiliation(s)
- Maria Pequito Luís
- Associate Laboratory i4HB, Institute for Health and Bioeconomy, NOVA School of Science and Technology, NOVA University Lisbon, Caparica, Portugal
- Department of Life Sciences, UCIBIO, Applied Molecular Biosciences Unit, NOVA School of Science and Technology, NOVA University Lisbon, Caparica, Portugal
| | - Inês Serrano Pereira
- Associate Laboratory i4HB, Institute for Health and Bioeconomy, NOVA School of Science and Technology, NOVA University Lisbon, Caparica, Portugal
- Department of Life Sciences, UCIBIO, Applied Molecular Biosciences Unit, NOVA School of Science and Technology, NOVA University Lisbon, Caparica, Portugal
| | - Joana N. Bugalhão
- Associate Laboratory i4HB, Institute for Health and Bioeconomy, NOVA School of Science and Technology, NOVA University Lisbon, Caparica, Portugal
- Department of Life Sciences, UCIBIO, Applied Molecular Biosciences Unit, NOVA School of Science and Technology, NOVA University Lisbon, Caparica, Portugal
| | - Catarina N. Simões
- Department of Life Sciences, UCIBIO, Applied Molecular Biosciences Unit, NOVA School of Science and Technology, NOVA University Lisbon, Caparica, Portugal
- Faculty of Sciences, University of Lisbon, Lisbon, Portugal
| | - Cristiano Mota
- Associate Laboratory i4HB, Institute for Health and Bioeconomy, NOVA School of Science and Technology, NOVA University Lisbon, Caparica, Portugal
- Department of Chemistry, UCIBIO, Applied Molecular Biosciences Unit, NOVA School of Science and Technology, NOVA University Lisbon, Caparica, Portugal
| | - Maria João Romão
- Associate Laboratory i4HB, Institute for Health and Bioeconomy, NOVA School of Science and Technology, NOVA University Lisbon, Caparica, Portugal
- Department of Chemistry, UCIBIO, Applied Molecular Biosciences Unit, NOVA School of Science and Technology, NOVA University Lisbon, Caparica, Portugal
| | - Luís Jaime Mota
- Associate Laboratory i4HB, Institute for Health and Bioeconomy, NOVA School of Science and Technology, NOVA University Lisbon, Caparica, Portugal
- Department of Life Sciences, UCIBIO, Applied Molecular Biosciences Unit, NOVA School of Science and Technology, NOVA University Lisbon, Caparica, Portugal
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Arif ED, Saeed NM, Rachid SK, Dyary HO, Rashid PM. Expression Level of the mip, pmp18D, and ompA Genes in Chlamydia abortus Isolated from Aborted Ewes. Pol J Microbiol 2022; 71:115-121. [PMID: 35635174 PMCID: PMC9152909 DOI: 10.33073/pjm-2022-014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Accepted: 02/20/2022] [Indexed: 11/22/2022] Open
Abstract
In this manuscript, we report the proteins macrophage infectivity potentiator (mip, CAB080), major outer membrane protein (momp, CAB048), and polymorphic outer membrane protein (pmp18D, CAB776) that are expressed in different times of pregnancy in mice infected with Chlamydia abortus. Enzootic abortion of ewes (EAE) by C. abortus, an obligate intracellular pathogen, is a critical zoonotic disease-causing significant economic loss to livestock farming globally. This study was carried out for the detection and characterization of macrophage infectivity potentiator (mip, CAB080), major outer membrane protein (momp, CAB048), and polymorphic outer membrane protein (pmp18D, CAB776) using RT-qPCR. These proteins are believed to be expressed as virulence factors in C. abortus isolated from aborted ewes. BALB/c mice (pregnant and nonpregnant) were used as an animal model to be injected intraperitoneally with C. abortus culture in Vero cells since the endometrial lymphoid tissues of these animals resembles that of ewes. Also, the short duration of pregnancy in mice makes them a suitable animal model for obstetric studies. Tissue samples were taken from the mice after 10, 15, and 20 days of pregnancy to compare the expression of the genes mip, pmp18D, and ompA. Transcription level was quantified using RT-qPCR, the GAPDH transcription quantification, as a normalization signal. Abortion occurred in pregnant mice, and apparent differences between the transcriptional levels of the mip, pmp18D, and ompA genes in the samples taken during different time intervals of pregnancy were not observed (p > 0.05). The result indicated that the three bacterial genes, mip, pmp18D, and ompA, play a role as virulence factors in abortion and are differentially expressed in pregnant and nonpregnant animals. Inactivation of the genes is suggested to confirm the hypothesis.
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Affiliation(s)
- Eman Dhahir Arif
- Department of Microbiology, College of Veterinary Medicine , University of Sulaimani , Sulaymaniyah , Iraq
| | - Nahla Mohammad Saeed
- Department of Microbiology, College of Veterinary Medicine , University of Sulaimani , Sulaymaniyah , Iraq
| | | | - Hiewa Othman Dyary
- Department of Basic Sciences, College of Veterinary Medicine , University of Sulaimani , Sulaymaniyah , Iraq
| | - Peshnyar M.A. Rashid
- Kurdistan Institution for Strategic Studies and Scientific Research , Sulaymaniyah , Iraq
- Molecular Diagnostic Laboratory , Directorate of Veterinary Services in Sulaymaniyah , Sulaymaniyah , Iraq
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Garvin LE, DeBoer AG, Carrell SJ, Wang X, Rockey DD. Microscopic Analysis of the Chlamydia abortus Inclusion and Its Interaction with Those Formed by Other Chlamydial Species. Infect Immun 2022; 90:e0049921. [PMID: 35099268 PMCID: PMC8929342 DOI: 10.1128/iai.00499-21] [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: 09/28/2021] [Accepted: 01/18/2022] [Indexed: 11/20/2022] Open
Abstract
The Chlamydiae are obligate intracellular pathogens that develop and multiply within a poorly characterized parasitophorous vacuole (the inclusion) during growth. Chlamydia abortus is a major pathogen of sheep and other ruminants, and its inclusion development is poorly characterized. We used immunofluorescence microscopy, quantitative culture, and qPCR to examine C. abortus inclusion development and to examine the interaction of C. abortus inclusions with those formed by other species. Antibodies used in these studies include sera from ewes from production facilities that were naturally infected with C. abortus. Multiple inclusions are often found in C. abortus-infected cells, even in populations infected at very low multiplicity of infection. Labeling of fixed cells with sera from infected sheep revealed fibrous structures that extend away from the inclusion into the cytoplasm of the host cell. C. abortus inclusions fused with C. caviae and C. psittaci inclusions in coinfected cells. Inclusions formed by C. abortus and C. caviae did not fuse with inclusions formed by C. trachomatis, C. pneumoniae, or C. pecorum. The ability of inclusions to fuse was correlated with the overall genomic relatedness between species, and with sequence similarity in the inclusion membrane protein IncA. Quantitative PCR data demonstrated that C. abortus grows at a decreased rate during coinfections with C. caviae, while C. caviae growth was unaffected. The collected data add depth to our understanding of inclusion development in this significant zoonotic veterinary pathogen.
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Affiliation(s)
- Lotisha E. Garvin
- Department of Biomedical Sciences, Carlson College of Veterinary Medicine, Oregon State University, Corvallis, Oregon, USA
| | - Addison G. DeBoer
- Department of Biomedical Sciences, Carlson College of Veterinary Medicine, Oregon State University, Corvallis, Oregon, USA
| | - Steven J. Carrell
- Department of Biomedical Sciences, Carlson College of Veterinary Medicine, Oregon State University, Corvallis, Oregon, USA
| | - Xisheng Wang
- Department of Biomedical Sciences, Carlson College of Veterinary Medicine, Oregon State University, Corvallis, Oregon, USA
| | - Daniel D. Rockey
- Department of Biomedical Sciences, Carlson College of Veterinary Medicine, Oregon State University, Corvallis, Oregon, USA
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10
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The Chlamydia trachomatis inclusion membrane protein CT006 associates with lipid droplets in eukaryotic cells. PLoS One 2022; 17:e0264292. [PMID: 35192658 PMCID: PMC8863265 DOI: 10.1371/journal.pone.0264292] [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: 12/08/2021] [Accepted: 02/07/2022] [Indexed: 11/19/2022] Open
Abstract
Chlamydia trachomatis causes genital and ocular infections in humans. This bacterial pathogen multiplies exclusively within host cells in a characteristic vacuole (inclusion) and delivers proteins such as inclusion membrane proteins (Incs) into the host cell. Here, we identified CT006 as a novel C. trachomatis protein that when expressed ectopically eukaryotic cells can associate with lipid droplets (LDs). A screen using Saccharomyces cerevisiae identified two Incs causing vacuolar protein sorting defects and seven Incs showing tropism for eukaryotic organelles. Ectopic expression in yeast and mammalian cells of genes encoding different fragments of CT006 revealed tropism for the endoplasmic reticulum and LDs. We identified a LD-targeting region within the first 88 amino acid residues of CT006, and positively charged residues important for this targeting. Comparing with the parental wild-type strain, cells infected by a newly generated C. trachomatis strain overproducing CT006 with a double hemagglutinin tag showed a slight increase in the area occupied by LDs within the inclusion region. However, we could not correlate this effect with the LD-targeting regions within CT006. We further showed that both the amino and carboxy-terminal regions of CT006, flanking the Inc-characteristic bilobed hydrophobic domain, are exposed to the host cell cytosol during C. trachomatis infection, supporting their availability to interact with host cell targets. Altogether, our data suggest that CT006 might participate in the interaction of LDs with C. trachomatis inclusions.
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11
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Dimond ZE, Suchland RJ, Baid S, LaBrie SD, Soules KR, Stanley J, Carrell S, Kwong F, Wang Y, Rockey DD, Hybiske K, Hefty PS. Inter-species lateral gene transfer focused on the Chlamydia plasticity zone identifies loci associated with immediate cytotoxicity and inclusion stability. Mol Microbiol 2021; 116:1433-1448. [PMID: 34738268 PMCID: PMC9119408 DOI: 10.1111/mmi.14832] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Accepted: 10/13/2021] [Indexed: 12/20/2022]
Abstract
Chlamydia muridarum actively grows in murine mucosae and is a representative model of human chlamydial genital tract disease. In contrast, C. trachomatis infections in mice are limited and rarely cause disease. The factors that contribute to these differences in host adaptation and specificity remain elusive. Overall genomic similarity leads to challenges in the understanding of these significant differences in tropism. A region of major genetic divergence termed the plasticity zone (PZ) has been hypothesized to contribute to the host specificity. To evaluate this hypothesis, lateral gene transfer was used to generate multiple hetero-genomic strains that are predominately C. trachomatis but have replaced regions of the PZ with those from C. muridarum. In vitro analysis of these chimeras revealed C. trachomatis-like growth as well as poor mouse infection capabilities. Growth-independent cytotoxicity phenotypes have been ascribed to three large putative cytotoxins (LCT) encoded in the C. muridarum PZ. However, analysis of PZ chimeras supported that gene products other than the LCTs are responsible for cytopathic and cytotoxic phenotypes. Growth analysis of associated chimeras also led to the discovery of an inclusion protein, CTL0402 (CT147), and homolog TC0424, which was critical for the integrity of the inclusion and preventing apoptosis.
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Affiliation(s)
- Zoe E. Dimond
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas, USA
| | - Robert J. Suchland
- Division of Allergy and Infectious Diseases, Department of Medicine, University of Washington, Seattle, Washington, USA
| | - Srishti Baid
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas, USA
| | - Scott D. LaBrie
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas, USA
| | - Katelyn R. Soules
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas, USA
| | - Jacob Stanley
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas, USA
| | - Steven Carrell
- Department of Biomedical Sciences, Oregon State University, Corvallis, Oregon, USA
| | - Forrest Kwong
- Division of Allergy and Infectious Diseases, Department of Medicine, University of Washington, Seattle, Washington, USA
| | - Yibing Wang
- Division of Allergy and Infectious Diseases, Department of Medicine, University of Washington, Seattle, Washington, USA
| | - Daniel D. Rockey
- Department of Biomedical Sciences, Oregon State University, Corvallis, Oregon, USA
| | - Kevin Hybiske
- Division of Allergy and Infectious Diseases, Department of Medicine, University of Washington, Seattle, Washington, USA
| | - P. Scott Hefty
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas, USA
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12
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Inclusion Membrane Growth and Composition Are Altered by Overexpression of Specific Inclusion Membrane Proteins in Chlamydia trachomatis L2. Infect Immun 2021; 89:e0009421. [PMID: 33875478 PMCID: PMC8208519 DOI: 10.1128/iai.00094-21] [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] [Indexed: 01/26/2023] Open
Abstract
Chlamydia trachomatis is the leading cause of bacterial sexually transmitted infections. This obligate intracellular bacterium develops within a membrane-bound vacuole called an inclusion, which sequesters the chlamydiae from the host cytoplasm. Host-pathogen interactions at this interface are mediated by chlamydial inclusion membrane proteins (Incs). However, the specific functions of most Incs are poorly characterized. Previous work from our laboratories indicated that expressing an IncF fusion protein at high levels in C. trachomatis L2 negatively impacted inclusion expansion and progeny production. We hypothesize that some Incs function in the structure and organization of the inclusion membrane and that overexpression of those Incs will alter the composition of endogenous Incs within the inclusion membrane. Consequently, inclusion biogenesis and chlamydial development are negatively impacted. To investigate this, C. trachomatis L2 was transformed with inducible expression plasmids encoding IncF-, CT813-, or CT226-FLAG. Overexpression of IncF-FLAG or CT813-FLAG, but not CT226-FLAG, altered chlamydial development, as demonstrated by smaller inclusions, fewer progeny, and increased plasmid loss. The overexpression of CT813-FLAG reduced the detectable levels of endogenous IncE and IncG in the inclusion membrane. Notably, recruitment of sorting nexin-6, a eukaryotic protein binding partner of IncE, was also reduced after CT813 overexpression. Gene expression studies and ultrastructural analysis of chlamydial organisms demonstrated that chlamydial development was altered when CT813-FLAG was overexpressed. Overall, these data indicate that disrupting the expression of specific Incs changed the composition of Incs within the inclusion membrane and the recruitment of associated host cell proteins, which negatively impacted C. trachomatis development.
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13
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Tang T, Wu H, Chen X, Chen L, Liu L, Li Z, Bai Q, Chen Y, Chen L. The Hypothetical Inclusion Membrane Protein CPSIT_0846 Regulates Mitochondrial-Mediated Host Cell Apoptosis via the ERK/JNK Signaling Pathway. Front Cell Infect Microbiol 2021; 11:607422. [PMID: 33747977 PMCID: PMC7971157 DOI: 10.3389/fcimb.2021.607422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Accepted: 01/26/2021] [Indexed: 11/13/2022] Open
Abstract
Chlamydia psittaci is an important zoonotic factor associated with human and animal atypical pneumonia. Resisting host cell apoptosis is central to sustaining Chlamydia infection in vivo. Chlamydia can secrete inclusion membrane proteins (Incs) that play important roles in their development cycle and pathogenesis. CPSIT_0846 is an Inc protein in C. psittaci identified by our team in previous work. In the current study, we investigated the regulatory role of CPSIT_0846 in HeLa cell apoptosis, and explored potential mechanisms. The results showed that HeLa cells treated with CPSIT_0846 contained fewer apoptotic bodies and exhibited a lower apoptotic rate than untreated cells either with Hoechst 33258 fluorescence staining or flow cytometry with or without induction by staurosporine (STS). CPSIT_0846 could increase the phosphorylation of the extracellular signal-regulated kinases 1/2 (ERK1/2) or stress-activated protein kinases/c-Jun amino-terminal kinases (SAPK/JNK) signaling pathways, and the Bcl-2 associated X protein (Bax)/B cell lymphoma 2 (Bcl-2) ratio, levels of cleaved caspase-3/9 and cleaved Poly-ADP-ribose polymerase (PARP) were significantly up-regulated following inhibition of ERK1/2 or SAPK/JNK pathways with U0126 or SP600125. After carbonyl cyanide 3-chlorophenylhydrazone (CCCP) treatment, the mitochondrial membrane potential (MMP) of cells was significantly decreased in control group, but stable in the CPSIT_0846 treated one, and less cytochrome c (Cyt.c) was released into the cytoplasm. Inhibition of the ERK1/2 or SAPK/JNK pathway significantly decreased the JC-1 red-green fluorescence signal, and promoted Cyt.c discharge into the cytoplasm in HeLa cells treated with CPSIT_0846. In conclusion, CPSIT_0846 can regulate mitochondrial pathway-mediated apoptosis in HeLa cells by activating the ERK/JNK signaling pathway.
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Affiliation(s)
- Ting Tang
- Department of Public Health Laboratory Sciences, College of Public Health, University of South China, Hengyang, China.,Key Laboratory of Hengyang for Health Hazard Factors Inspection and Quarantine, College of Public Health, University of South China, Hengyang, China.,Department of Infection Control, The First People's Hospital of Yunnan Province, The Affiliated Hospital of Kunming University of Science and Technology, Kunming, China
| | - Haiying Wu
- Department of Laboratory Medicine, The Second Affiliated Hospital of University of South China, Hengyang, China
| | - Xi Chen
- Department of Public Health Laboratory Sciences, College of Public Health, University of South China, Hengyang, China.,Key Laboratory of Hengyang for Health Hazard Factors Inspection and Quarantine, College of Public Health, University of South China, Hengyang, China
| | - Li Chen
- Department of Public Health Laboratory Sciences, College of Public Health, University of South China, Hengyang, China.,Key Laboratory of Hengyang for Health Hazard Factors Inspection and Quarantine, College of Public Health, University of South China, Hengyang, China
| | - Luyao Liu
- Department of Public Health Laboratory Sciences, College of Public Health, University of South China, Hengyang, China.,Key Laboratory of Hengyang for Health Hazard Factors Inspection and Quarantine, College of Public Health, University of South China, Hengyang, China
| | - Zhongyu Li
- Institute of Pathogenic Biology, Hengyang Medical College, University of South China, Hengyang, China
| | - Qinqin Bai
- Department of Public Health Laboratory Sciences, College of Public Health, University of South China, Hengyang, China.,Key Laboratory of Hengyang for Health Hazard Factors Inspection and Quarantine, College of Public Health, University of South China, Hengyang, China
| | - Yuyu Chen
- Hunan Cancer Hospital and The Affiliated Cancer Hospital of Xiangya School of Medicine, Central South University, Changsha, China
| | - Lili Chen
- Department of Public Health Laboratory Sciences, College of Public Health, University of South China, Hengyang, China.,Key Laboratory of Hengyang for Health Hazard Factors Inspection and Quarantine, College of Public Health, University of South China, Hengyang, China
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14
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Eukaryotic SNARE VAMP3 Dynamically Interacts with Multiple Chlamydial Inclusion Membrane Proteins. Infect Immun 2021; 89:IAI.00409-20. [PMID: 33229367 PMCID: PMC7822134 DOI: 10.1128/iai.00409-20] [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: 07/06/2020] [Accepted: 11/15/2020] [Indexed: 01/13/2023] Open
Abstract
Chlamydia trachomatis, an obligate intracellular pathogen, undergoes a biphasic developmental cycle within a membrane-bound vacuole called the chlamydial inclusion. To facilitate interactions with the host cell, Chlamydia modifies the inclusion membrane with type III secreted proteins, called Incs. Chlamydia trachomatis, an obligate intracellular pathogen, undergoes a biphasic developmental cycle within a membrane-bound vacuole called the chlamydial inclusion. To facilitate interactions with the host cell, Chlamydia modifies the inclusion membrane with type III secreted proteins, called Incs. As with all chlamydial proteins, Incs are temporally expressed, modifying the chlamydial inclusion during the early and mid-developmental cycle. VAMP3 and VAMP4 are eukaryotic SNARE proteins that mediate membrane fusion and are recruited to the inclusion to facilitate inclusion expansion. Their recruitment requires de novo chlamydial protein synthesis during the mid-developmental cycle. Thus, we hypothesize that VAMP3 and VAMP4 are recruited by Incs. In chlamydia-infected cells, identifying Inc binding partners for SNARE proteins specifically has been elusive. To date, most studies examining chlamydial Inc and eukaryotic proteins have benefitted from stable interacting partners or a robust interaction at a specific time postinfection. While these types of interactions are the predominant class that have been identified, they are likely the exception to chlamydia-host interactions. Therefore, we applied two separate but complementary experimental systems to identify candidate chlamydial Inc binding partners for VAMPs. Based on these results, we created transformed strains of C. trachomatis serovar L2 to inducibly express a candidate Inc-FLAG protein. In chlamydia-infected cells, we found that five Incs temporally and transiently interact with VAMP3. Further, loss of incA or ct813 expression altered VAMP3 localization to the inclusion. For the first time, our studies demonstrate the transient nature of certain host protein-Inc interactions that contribute to the chlamydial developmental cycle.
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15
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Hijacking and Use of Host Kinases by Chlamydiae. Pathogens 2020; 9:pathogens9121034. [PMID: 33321710 PMCID: PMC7763869 DOI: 10.3390/pathogens9121034] [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] [Received: 10/10/2020] [Revised: 12/01/2020] [Accepted: 12/07/2020] [Indexed: 12/11/2022] Open
Abstract
Chlamydia species are causative agents of sexually transmitted infections, blinding trachoma, and animal infections with zoonotic potential. Being an obligate intracellular pathogen, Chlamydia relies on the host cell for its survival and development, subverting various host cell processes throughout the infection cycle. A key subset of host proteins utilized by Chlamydia include an assortment of host kinase signaling networks which are vital for many chlamydial processes including entry, nutrient acquisition, and suppression of host cell apoptosis. In this review, we summarize the recent advancements in our understanding of host kinase subversion by Chlamydia.
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16
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Hausman JM, Kenny S, Iyer S, Babar A, Qiu J, Fu J, Luo ZQ, Das C. The Two Deubiquitinating Enzymes from Chlamydia trachomatis Have Distinct Ubiquitin Recognition Properties. Biochemistry 2020; 59:1604-1617. [PMID: 32275137 PMCID: PMC7700883 DOI: 10.1021/acs.biochem.9b01107] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Chlamydia trachomatis is the cause of several diseases such as sexually transmitted urogenital disease and ocular trachoma. The pathogen contains a small genome yet, upon infection, expresses two enzymes with deubiquitinating activity, termed ChlaDUB1 and ChlaDUB2, presumed to have redundant deubiquitinase (DUB) function because of the similarity of the primary structure of their catalytic domain. Previous studies have led to structural characterization of the enzymatic properties of ChlaDUB1; however, ChlaDUB2 has yet to be investigated thoroughly. In this study, we investigated the deubiquitinase properties of ChlaDUB2 and compared them to those of ChlaDUB1. This revealed a distinct difference in hydrolytic activity with regard to di- and polyubiquitin chains while showing similar ability to cleave a monoubiquitin-based substrate, ubiquitin aminomethylcoumarin (Ub-AMC). ChlaDUB2 was unable to cleave a diubiquitin substrate efficiently, whereas ChlaDUB1 could rapidly hydrolyze this substrate like a prototypical prokaryotic DUB, SdeA. With polyubiquitinated green fluorescent protein substrate (GFP-Ubn), whereas ChlaDUB1 efficiently disassembled the polyubiquitin chains into the monoubiquitin product, the deubiquitination activity of ChlaDUB2, while showing depletion of the substrate, did not produce appreciable levels of the monoubiquitin product. We report the structures of a catalytic construct of ChlaDUB2 and its complex with ubiquitin propargyl amide. These structures revealed differences in residues involved in substrate recognition between the two Chlamydia DUBs. On the basis of the structures, we conclude that the distal ubiquitin binding is equivalent between the two DUBs, consistent with the Ub-AMC activity result. Therefore, the difference in activity with longer ubiquitinated substrates may be due to the differential recognition of these substrates involving additional ubiquitin binding sites.
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Affiliation(s)
- John M. Hausman
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
| | - Sebastian Kenny
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
| | - Shalini Iyer
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
| | - Aditya Babar
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States
| | - Jiazhang Qiu
- Key Laboratory of Zoonosis, Ministry of Education, Institute of Zoonosis, College of Veterinary Medicine, Jilin University, Xi’an Road 5333, Changchun, Jilin 130062, China
| | - Jiaqi Fu
- Department of Biology, Purdue University, West Lafayette, Indiana 47907, United States
| | - Zhao-Qing Luo
- Department of Biology, Purdue University, West Lafayette, Indiana 47907, United States
| | - Chittaranjan Das
- Department of Chemistry, Purdue University, 560 Oval Drive, West Lafayette, Indiana 47907, United States,Corresponding Author:
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17
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A predation assay using amoebae to screen for virulence factors unearthed the first W. chondrophila inclusion membrane protein. Sci Rep 2019; 9:19485. [PMID: 31862969 PMCID: PMC6925127 DOI: 10.1038/s41598-019-55511-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Accepted: 11/11/2019] [Indexed: 01/21/2023] Open
Abstract
Waddlia chondrophila is an intracellular bacterium phylogenetically related to the well-studied human and animal pathogens of the Chlamydiaceae family. In the last decade, W. chondrophila was convincingly demonstrated to be associated with adverse pregnancy outcomes in humans and abortions in animals. All members of the phylum Chlamydiae possess a Type Three Secretion System that they use for delivering virulence proteins into the host cell cytosol to modulate their environment and create optimal conditions to complete their life cycle. To identify W. chondrophila virulence proteins, we used an original screening approach that combines a cosmid library with an assay monitoring resistance to predation by phagocytic amoebae. This technique combined with bioinformatic data allowed the identification of 28 candidate virulence proteins, including Wimp1, the first identified inclusion membrane protein of W. chondrophila.
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18
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Insertional mutagenesis in the zoonotic pathogen Chlamydia caviae. PLoS One 2019; 14:e0224324. [PMID: 31697687 PMCID: PMC6837515 DOI: 10.1371/journal.pone.0224324] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Accepted: 10/11/2019] [Indexed: 11/19/2022] Open
Abstract
The ability to introduce targeted genetic modifications in microbial genomes has revolutionized our ability to study the role and mode of action of individual bacterial virulence factors. Although the fastidious lifestyle of obligate intracellular bacterial pathogens poses a technical challenge to such manipulations, the last decade has produced significant advances in our ability to conduct molecular genetic analysis in Chlamydia trachomatis, a major bacterial agent of infertility and blindness. Similar approaches have not been established for the closely related veterinary Chlamydia spp., which cause significant economic damage, as well as rare but potentially life-threatening infections in humans. Here we demonstrate the feasibility of conducting site-specific mutagenesis for disrupting virulence genes in C. caviae, an agent of guinea pig inclusion conjunctivitis that was recently identified as a zoonotic agent in cases of severe community-acquired pneumonia. Using this approach, we generated C. caviae mutants deficient for the secreted effector proteins IncA and SinC. We demonstrate that C. caviae IncA plays a role in mediating fusion of the bacteria-containing vacuoles inhabited by C. caviae. Moreover, using a chicken embryo infection model, we provide first evidence for a role of SinC in C. caviae virulence in vivo.
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19
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Proximity Labeling To Map Host-Pathogen Interactions at the Membrane of a Bacterium-Containing Vacuole in Chlamydia trachomatis-Infected Human Cells. Infect Immun 2019; 87:IAI.00537-19. [PMID: 31405957 PMCID: PMC6803327 DOI: 10.1128/iai.00537-19] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2019] [Accepted: 08/06/2019] [Indexed: 02/06/2023] Open
Abstract
Many intracellular bacteria, including the obligate intracellular pathogen Chlamydia trachomatis, grow within a membrane-bound bacterium-containing vacuole (BCV). Secreted cytosolic effectors modulate host activity, but an understanding of the host-pathogen interactions that occur at the BCV membrane is limited by the difficulty in purifying membrane fractions from infected host cells. Many intracellular bacteria, including the obligate intracellular pathogen Chlamydia trachomatis, grow within a membrane-bound bacterium-containing vacuole (BCV). Secreted cytosolic effectors modulate host activity, but an understanding of the host-pathogen interactions that occur at the BCV membrane is limited by the difficulty in purifying membrane fractions from infected host cells. We used the ascorbate peroxidase (APEX2) proximity labeling system, which labels proximal proteins with biotin in vivo, to study the protein-protein interactions that occur at the chlamydial vacuolar, or inclusion, membrane. An in vivo understanding of the secreted chlamydial inclusion membrane protein (Inc) interactions (e.g., Inc-Inc and Inc-eukaryotic protein) and how these contribute to overall host-chlamydia interactions at this unique membrane is lacking. We hypothesize some Incs organize the inclusion membrane, whereas other Incs bind eukaryotic proteins to promote chlamydia-host interactions. To study this, Incs fused to APEX2 were expressed in C. trachomatis L2. Affinity purification-mass spectrometry (AP-MS) identified biotinylated proteins, which were analyzed for statistical significance using significance analysis of the interactome (SAINT). Broadly supporting both Inc-Inc and Inc-host interactions, our Inc-APEX2 constructs labeled Incs as well as known and previously unreported eukaryotic proteins localizing to the inclusion. We demonstrate, using bacterial two-hybrid and coimmunoprecipitation assays, that endogenous LRRFIP1 (LRRF1) is recruited to the inclusion by the Inc CT226. We further demonstrate interactions between CT226 and the Incs used in our study to reveal a model for inclusion membrane organization. Combined, our data highlight the utility of APEX2 to capture the complex in vivo protein-protein interactions at the chlamydial inclusion.
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20
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Gitsels A, Sanders N, Vanrompay D. Chlamydial Infection From Outside to Inside. Front Microbiol 2019; 10:2329. [PMID: 31649655 PMCID: PMC6795091 DOI: 10.3389/fmicb.2019.02329] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2019] [Accepted: 09/24/2019] [Indexed: 12/16/2022] Open
Abstract
Chlamydia are obligate intracellular bacteria, characterized by a unique biphasic developmental cycle. Specific interactions with the host cell are crucial for the bacteria’s survival and amplification because of the reduced chlamydial genome. At the start of infection, pathogen-host interactions are set in place in order for Chlamydia to enter the host cell and reach the nutrient-rich peri-Golgi region. Once intracellular localization is established, interactions with organelles and pathways of the host cell enable the necessary hijacking of host-derived nutrients. Detailed information on the aforementioned processes will increase our understanding on the intracellular pathogenesis of chlamydiae and hence might lead to new strategies to battle chlamydial infection. This review summarizes how chlamydiae generate their intracellular niche in the host cell, acquire host-derived nutrients in order to enable their growth and finally exit the host cell in order to infect new cells. Moreover, the evolution in the development of molecular genetic tools, necessary for studying the chlamydial infection biology in more depth, is discussed in great detail.
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Affiliation(s)
- Arlieke Gitsels
- Laboratory for Immunology and Animal Biotechnology, Department of Animal Sciences and Aquatic Ecology, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
| | - Niek Sanders
- Laboratory of Gene Therapy, Department of Nutrition, Genetics and Ethology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - Daisy Vanrompay
- Laboratory for Immunology and Animal Biotechnology, Department of Animal Sciences and Aquatic Ecology, Faculty of Bioscience Engineering, Ghent University, Ghent, Belgium
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21
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Bugalhão JN, Mota LJ. The multiple functions of the numerous Chlamydia trachomatis secreted proteins: the tip of the iceberg. MICROBIAL CELL 2019; 6:414-449. [PMID: 31528632 PMCID: PMC6717882 DOI: 10.15698/mic2019.09.691] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Chlamydia trachomatis serovars are obligate intracellular bacterial pathogens mainly causing ocular and urogenital infections that affect millions of people worldwide and which can lead to blindness or sterility. They reside and multiply intracellularly within a membrane-bound vacuolar compartment, known as inclusion, and are characterized by a developmental cycle involving two morphologically and physiologically distinct chlamydial forms. Completion of the developmental cycle involves the secretion of > 70 C. trachomatis proteins that function in the host cell cytoplasm and nucleus, in the inclusion membrane and lumen, and in the extracellular milieu. These proteins can, for example, interfere with the host cell cytoskeleton, vesicular and non-vesicular transport, metabolism, and immune signalling. Generally, this promotes C. trachomatis invasion into, and escape from, host cells, the acquisition of nutrients by the chlamydiae, and evasion of cell-autonomous, humoral and cellular innate immunity. Here, we present an in-depth review on the current knowledge and outstanding questions about these C. trachomatis secreted proteins.
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Affiliation(s)
- Joana N Bugalhão
- UCIBIO, Departamento de Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, Caparica, Portugal
| | - Luís Jaime Mota
- UCIBIO, Departamento de Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, Caparica, Portugal
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22
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Cingolani G, McCauley M, Lobley A, Bryer AJ, Wesolowski J, Greco DL, Lokareddy RK, Ronzone E, Perilla JR, Paumet F. Structural basis for the homotypic fusion of chlamydial inclusions by the SNARE-like protein IncA. Nat Commun 2019; 10:2747. [PMID: 31227715 PMCID: PMC6588587 DOI: 10.1038/s41467-019-10806-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 05/29/2019] [Indexed: 11/29/2022] Open
Abstract
Many intracellular bacteria, including Chlamydia, establish a parasitic membrane-bound organelle inside the host cell that is essential for the bacteria’s survival. Chlamydia trachomatis forms inclusions that are decorated with poorly characterized membrane proteins known as Incs. The prototypical Inc, called IncA, enhances Chlamydia pathogenicity by promoting the homotypic fusion of inclusions and shares structural and functional similarity to eukaryotic SNAREs. Here, we present the atomic structure of the cytoplasmic domain of IncA, which reveals a non-canonical four-helix bundle. Structure-based mutagenesis, molecular dynamics simulation, and functional cellular assays identify an intramolecular clamp that is essential for IncA-mediated homotypic membrane fusion during infection. Chlamydia trachomatis forms membrane-bound inclusions inside the host cell that are decorated with IncA, a SNARE-like protein that promotes the fusion of inclusions. Here, Cingolani et al. show that the protein folds into a non-canonical four-helix bundle and identify an intramolecular clamp required for membrane fusion.
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Affiliation(s)
- Gino Cingolani
- Thomas Jefferson University, Department of Biochemistry and Molecular Biology, Philadelphia, PA, 19107, USA. .,Institute of Biomembranes and Bioenergetics, National Research Council, Via Amendola 165/A, 70126, Bari, Italy.
| | - Michael McCauley
- Thomas Jefferson University, Department of Microbiology and Immunology, Philadelphia, PA, 19107, USA.,Janssen Research and Development, Spring House, PA, 19477, USA
| | - Anna Lobley
- Thomas Jefferson University, Department of Microbiology and Immunology, Philadelphia, PA, 19107, USA
| | - Alexander J Bryer
- The University of Delaware, Department of Chemistry and Biochemistry, Newark, DE, 19716, USA
| | - Jordan Wesolowski
- Thomas Jefferson University, Department of Microbiology and Immunology, Philadelphia, PA, 19107, USA
| | - Deanna L Greco
- The University of Delaware, Department of Chemistry and Biochemistry, Newark, DE, 19716, USA
| | - Ravi K Lokareddy
- Thomas Jefferson University, Department of Biochemistry and Molecular Biology, Philadelphia, PA, 19107, USA
| | - Erik Ronzone
- Thomas Jefferson University, Department of Microbiology and Immunology, Philadelphia, PA, 19107, USA.,VUE Health, Boston, MA, 02110, USA
| | - Juan R Perilla
- The University of Delaware, Department of Chemistry and Biochemistry, Newark, DE, 19716, USA
| | - Fabienne Paumet
- Thomas Jefferson University, Department of Microbiology and Immunology, Philadelphia, PA, 19107, USA.
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23
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Pais SV, Key CE, Borges V, Pereira IS, Gomes JP, Fisher DJ, Mota LJ. CteG is a Chlamydia trachomatis effector protein that associates with the Golgi complex of infected host cells. Sci Rep 2019; 9:6133. [PMID: 30992493 PMCID: PMC6468002 DOI: 10.1038/s41598-019-42647-3] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Accepted: 03/22/2019] [Indexed: 12/17/2022] Open
Abstract
Chlamydia trachomatis is a bacterial pathogen causing ocular and genital infections in humans. C. trachomatis multiplies exclusively inside host cells within a characteristic vacuole, from where it manipulates host cells by injecting them with type III secretion effector proteins. Here, we identified CteG as the first C. trachomatiseffector associated with the Golgi. For this, C. trachomatis strains expressing candidate effectors fused to a double hemagglutinin (2HA) tag were constructed. Then, among these strains, immunofluorescence microscopy revealed that CteG-2HA was delivered into the cytoplasm of infected cells. Between 16–20 h post-infection, CteG-2HA mostly associated with the Golgi; however, CteG-2HA also appeared at the host cell plasma membrane, and at 30 or 40 h post-infection this was its predominant localization. This change in the main localization of CteG-2HA was independent of intact microfilaments or microtubules. Ectopic expression of different regions of CteG (656 amino acid residues) in uninfected cells revealed that its first 100 residues contain a Golgi targeting region. Although a C. trachomatis cteG mutant did not display a defect in intracellular multiplication, CteG induced a vacuolar protein sorting defect when expressed in Saccharomyces cerevisiae. This suggested that CteG might function by subverting host cell vesicular transport.
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Affiliation(s)
- Sara V Pais
- UCIBIO, Departamento de Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, Caparica, Portugal
| | - Charlotte E Key
- Department of Microbiology, Southern Illinois University, Carbondale, Illinois, USA
| | - Vítor Borges
- Bioinformatics Unit, Department of Infectious Diseases, National Institute of Health, Lisbon, Portugal
| | - Inês S Pereira
- UCIBIO, Departamento de Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, Caparica, Portugal
| | - João Paulo Gomes
- Bioinformatics Unit, Department of Infectious Diseases, National Institute of Health, Lisbon, Portugal
| | - Derek J Fisher
- Department of Microbiology, Southern Illinois University, Carbondale, Illinois, USA
| | - Luís Jaime Mota
- UCIBIO, Departamento de Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade NOVA de Lisboa, Caparica, Portugal.
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24
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Dickinson MS, Anderson LN, Webb-Robertson BJM, Hansen JR, Smith RD, Wright AT, Hybiske K. Proximity-dependent proteomics of the Chlamydia trachomatis inclusion membrane reveals functional interactions with endoplasmic reticulum exit sites. PLoS Pathog 2019; 15:e1007698. [PMID: 30943267 PMCID: PMC6464245 DOI: 10.1371/journal.ppat.1007698] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2018] [Revised: 04/15/2019] [Accepted: 03/12/2019] [Indexed: 11/18/2022] Open
Abstract
Chlamydia trachomatis is the most common cause of bacterial sexually transmitted infection, responsible for millions of infections each year. Despite this high prevalence, the elucidation of the molecular mechanisms of Chlamydia pathogenesis has been difficult due to limitations in genetic tools and its intracellular developmental cycle. Within a host epithelial cell, chlamydiae replicate within a vacuole called the inclusion. Many Chlamydia-host interactions are thought to be mediated by the Inc family of type III secreted proteins that are anchored in the inclusion membrane, but their array of host targets are largely unknown. To investigate how the inclusion membrane proteome changes over the course of an infected cell, we have adapted the APEX2 system of proximity-dependent biotinylation. APEX2 is capable of specifically labeling proteins within a 20 nm radius in living cells. We transformed C. trachomatis to express the enzyme APEX2 fused to known inclusion membrane proteins, allowing biotinylation and purification of inclusion-associated proteins. Using quantitative mass spectrometry against APEX2 labeled samples, we identified over 400 proteins associated with the inclusion membrane at early, middle, and late stages of epithelial cell infection. This system was sensitive enough to detect inclusion interacting proteins early in the developmental cycle, at 8 hours post infection, a previously intractable time point. Mass spectrometry analysis revealed a novel, early association between C. trachomatis inclusions and endoplasmic reticulum exit sites (ERES), functional regions of the ER where COPII-coated vesicles originate. Pharmacological and genetic disruption of ERES function severely restricted early chlamydial growth and the development of infectious progeny. APEX2 is therefore a powerful in situ approach for identifying critical protein interactions on the membranes of pathogen-containing vacuoles. Furthermore, the data derived from proteomic mapping of Chlamydia inclusions has illuminated an important functional role for ERES in promoting chlamydial developmental growth.
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Affiliation(s)
- Mary S. Dickinson
- Department of Global Health, Graduate Program in Pathobiology, University of Washington, Seattle, WA, United States of America
- Department of Medicine, Division of Allergy and Infectious Diseases, Center for Emerging and Reemerging Infectious Disease (CERID), University of Washington, Seattle, WA, United States of America
| | - Lindsey N. Anderson
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, United States of America
| | | | - Joshua R. Hansen
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, United States of America
| | - Richard D. Smith
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, United States of America
| | - Aaron T. Wright
- Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, United States of America
- The Gene and Linda Voiland College of Chemical Engineering and Bioengineering, Washington State University, Pullman, WA, United States of America
| | - Kevin Hybiske
- Department of Global Health, Graduate Program in Pathobiology, University of Washington, Seattle, WA, United States of America
- Department of Medicine, Division of Allergy and Infectious Diseases, Center for Emerging and Reemerging Infectious Disease (CERID), University of Washington, Seattle, WA, United States of America
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25
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Desai M, Wurihan W, Di R, Fondell JD, Nickels BE, Bao X, Fan H. Role for GrgA in Regulation of σ 28-Dependent Transcription in the Obligate Intracellular Bacterial Pathogen Chlamydia trachomatis. J Bacteriol 2018; 200:e00298-18. [PMID: 30061357 PMCID: PMC6153665 DOI: 10.1128/jb.00298-18] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Accepted: 07/27/2018] [Indexed: 12/22/2022] Open
Abstract
The obligate intracellular bacterial pathogen Chlamydia trachomatis has a unique developmental cycle consisting of two contrasting cellular forms. Whereas the primary Chlamydia sigma factor, σ66, is involved in the expression of the majority of chlamydial genes throughout the developmental cycle, expression of several late genes requires the alternative sigma factor, σ28 In prior work, we identified GrgA as a Chlamydia-specific transcription factor that activates σ66-dependent transcription by binding DNA and interacting with a nonconserved region (NCR) of σ66 Here, we extend these findings by showing GrgA can also activate σ28-dependent transcription through direct interaction with σ28 We measure the binding affinity of GrgA for both σ66 and σ28, and we identify regions of GrgA important for σ28-dependent transcription. Similar to results obtained with σ66, we find that GrgA's interaction with σ28 involves an NCR located upstream of conserved region 2 of σ28 Our findings suggest that GrgA is an important regulator of both σ66- and σ28-dependent transcription in C. trachomatis and further highlight NCRs of bacterial RNA polymerase as targets for regulatory factors unique to particular organisms.IMPORTANCEChlamydia trachomatis is the number one sexually transmitted bacterial pathogen worldwide. A substantial proportion of C. trachomatis-infected women develop infertility, pelvic inflammatory syndrome, and other serious complications. C. trachomatis is also a leading infectious cause of blindness in underdeveloped countries. The pathogen has a unique developmental cycle that is transcriptionally regulated. The discovery of an expanded role for the Chlamydia-specific transcription factor GrgA helps us understand the progression of the chlamydial developmental cycle.
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Affiliation(s)
- Malhar Desai
- Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey, USA
- Graduate Program in Physiology and Integrative Biology, School of Graduate Studies, Rutgers University, New Jersey, USA
| | - Wurihan Wurihan
- Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey, USA
| | - Rong Di
- Department of Plant Biology, School of Environmental and Biological Sciences, Rutgers University, New Brunswick, New Jersey, USA
| | - Joseph D Fondell
- Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey, USA
- Graduate Program in Physiology and Integrative Biology, School of Graduate Studies, Rutgers University, New Jersey, USA
| | - Bryce E Nickels
- Waksman Institute of Microbiology, Rutgers University, Piscataway, New Jersey, USA
| | - Xiaofeng Bao
- Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey, USA
- Department of Pharmacology, School of Pharmacy, Nantong University, Nantong, China
| | - Huizhou Fan
- Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey, USA
- Graduate Program in Physiology and Integrative Biology, School of Graduate Studies, Rutgers University, New Jersey, USA
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26
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Almeida F, Luís MP, Pereira IS, Pais SV, Mota LJ. The Human Centrosomal Protein CCDC146 Binds Chlamydia trachomatis Inclusion Membrane Protein CT288 and Is Recruited to the Periphery of the Chlamydia-Containing Vacuole. Front Cell Infect Microbiol 2018; 8:254. [PMID: 30094225 PMCID: PMC6070772 DOI: 10.3389/fcimb.2018.00254] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Accepted: 07/04/2018] [Indexed: 01/12/2023] Open
Abstract
Chlamydia trachomatis is an obligate intracellular human pathogen causing mainly ocular and genital infections of significant clinical and public health impact. C. trachomatis multiplies intracellularly in a membrane bound vacuole, known as inclusion. Both extracellularly and from within the inclusion, C. trachomatis uses a type III secretion system to deliver several effector proteins into the cytoplasm of host cells. A large proportion of these effectors, the inclusion membrane (Inc) proteins, are exposed to the host cell cytosol but possess a characteristic hydrophobic domain mediating their insertion in the inclusion membrane. By yeast two-hybrid, we found that C. trachomatis Inc CT288 interacts with the human centrosomal protein CCDC146 (coiled-coil domain-containing protein 146). The interaction was also detected by co-immunoprecipitation in mammalian cells either ectopically expressing CCDC146 and CT288 or ectopically expressing CCDC146 and infected by a C. trachomatis strain expressing epitope-tagged and inclusion membrane-localized CT288. In uninfected mammalian cells, ectopically expressed full-length CCDC146 (955 amino acid residues) localized at the centrosome; but in cells infected by wild-type C. trachomatis, its centrosomal localization was less evident and CCDC146 accumulated around the inclusion. Recruitment of CCDC146 to the inclusion periphery did not require intact host Golgi, microtubules or microfilaments, but was dependent on chlamydial protein synthesis. Full-length CCDC146 also accumulated at the periphery of the inclusion in cells infected by a C. trachomatis ct288 mutant; however, a C-terminal fragment of CCDC146 (residues 692–955), which interacts with CT288, showed differences in localization at the periphery of the inclusion in cells infected by wild-type or ct288 mutant C. trachomatis. This suggests a model in which chlamydial proteins other than CT288 recruit CCDC146 to the periphery of the inclusion, where the CT288-CCDC146 interaction might contribute to modulate the function of this host protein.
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Affiliation(s)
- Filipe Almeida
- Research Unit on Applied Molecular Biosciences (UCIBIO) - REQUIMTE, Departamento de Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Costa da Caparica, Portugal.,Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
| | - Maria P Luís
- Research Unit on Applied Molecular Biosciences (UCIBIO) - REQUIMTE, Departamento de Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Costa da Caparica, Portugal
| | - Inês Serrano Pereira
- Research Unit on Applied Molecular Biosciences (UCIBIO) - REQUIMTE, Departamento de Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Costa da Caparica, Portugal
| | - Sara V Pais
- Research Unit on Applied Molecular Biosciences (UCIBIO) - REQUIMTE, Departamento de Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Costa da Caparica, Portugal
| | - Luís Jaime Mota
- Research Unit on Applied Molecular Biosciences (UCIBIO) - REQUIMTE, Departamento de Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, Costa da Caparica, Portugal.,Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal
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27
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Elwell C, Engel J. Emerging Role of Retromer in Modulating Pathogen Growth. Trends Microbiol 2018; 26:769-780. [PMID: 29703496 DOI: 10.1016/j.tim.2018.04.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Revised: 03/21/2018] [Accepted: 04/02/2018] [Indexed: 12/20/2022]
Abstract
Intracellular pathogens have developed elegant mechanisms to modulate host endosomal trafficking. The highly conserved retromer pathway has emerged as an important target of viruses and intravacuolar bacteria. Some pathogens require retromer function to survive. For others, retromer activity restricts intracellular growth; these pathogens must disrupt retromer function to survive. In this review, we discuss recent paradigm changes to the current model for retromer assembly and cargo selection. We highlight how the study of pathogen effectors has contributed to these fundamental insights, with a special focus on the biology and structure of two recently described bacterial effectors, Chlamydia trachomatis IncE and Legionella pneumophila RidL. These two pathogens employ distinct strategies to target retromer components and overcome restriction of intracellular growth imposed by retromer.
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Affiliation(s)
- Cherilyn Elwell
- Department of Medicine, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Joanne Engel
- Department of Medicine, University of California, San Francisco, San Francisco, CA 94143, USA; Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA 94143, USA.
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28
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Haferkamp I. Crossing the border - Solute entry into the chlamydial inclusion. Int J Med Microbiol 2017; 308:41-48. [PMID: 28864236 DOI: 10.1016/j.ijmm.2017.08.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Revised: 08/10/2017] [Accepted: 08/17/2017] [Indexed: 10/19/2022] Open
Abstract
Chlamydiales comprise important human and animal pathogens as well as endosymbionts of amoebae. Generally, these obligate intracellular living bacteria are characterized by a biphasic developmental cycle, a reduced genome and a restricted metabolic capacity. Because of their metabolic impairment, Chlamydiales essentially rely on the uptake of diverse metabolites from their hosts. Chlamydiales thrive in a special compartment, the inclusion, and hence are surrounded by an additional membrane. Solutes might enter the inclusion through pores and open channels or by redirection of host vesicles, which fuse with the inclusion membrane and release their internal cargo. Recent investigations shed new light on the chlamydia-host interaction and identified an additional way for nutrient uptake into the inclusion. Proteome studies and targeting analyses identified chlamydial and host solute carriers in inclusions of Chlamydia trachomatis infected cells. These transporters are involved in the provision of UDP-glucose and biotin, and probably deliver further metabolites to the inclusion. By the controlled recruitment of specific solute carriers to the inclusion, the chlamydial resident thus can actively manipulate the metabolite availability and composition in the inclusion. This review summarizes recent findings and new ideas on carrier mediated solute uptake into the chlamydial inclusion in the context of the bacterial and host metabolism.
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Affiliation(s)
- Ilka Haferkamp
- Universität Kaiserslautern, Pflanzenphysiologie, Erwin-Schrödinger Str. 22, 67663 Kaiserslautern, Germany.
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29
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Elwell CA, Czudnochowski N, von Dollen J, Johnson JR, Nakagawa R, Mirrashidi K, Krogan NJ, Engel JN, Rosenberg OS. Chlamydia interfere with an interaction between the mannose-6-phosphate receptor and sorting nexins to counteract host restriction. eLife 2017; 6. [PMID: 28252385 PMCID: PMC5364026 DOI: 10.7554/elife.22709] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Accepted: 02/26/2017] [Indexed: 02/02/2023] Open
Abstract
Chlamydia trachomatis is an obligate intracellular pathogen that resides in a membrane-bound compartment, the inclusion. The bacteria secrete a unique class of proteins, Incs, which insert into the inclusion membrane and modulate the host-bacterium interface. We previously reported that IncE binds specifically to the Sorting Nexin 5 Phox domain (SNX5-PX) and disrupts retromer trafficking. Here, we present the crystal structure of the SNX5-PX:IncE complex, showing IncE bound to a unique and highly conserved hydrophobic groove on SNX5. Mutagenesis of the SNX5-PX:IncE binding surface disrupts a previously unsuspected interaction between SNX5 and the cation-independent mannose-6-phosphate receptor (CI-MPR). Addition of IncE peptide inhibits the interaction of CI-MPR with SNX5. Finally, C. trachomatis infection interferes with the SNX5:CI-MPR interaction, suggesting that IncE and CI-MPR are dependent on the same binding surface on SNX5. Our results provide new insights into retromer assembly and underscore the power of using pathogens to discover disease-related cell biology.
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Affiliation(s)
- Cherilyn A Elwell
- Department of Medicine, University of California, San Francisco, San Francisco, United States
| | - Nadine Czudnochowski
- Department of Medicine, University of California, San Francisco, San Francisco, United States
| | - John von Dollen
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, United States
| | - Jeffrey R Johnson
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, United States
| | - Rachel Nakagawa
- Department of Medicine, University of California, San Francisco, San Francisco, United States
| | - Kathleen Mirrashidi
- Department of Medicine, University of California, San Francisco, San Francisco, United States
| | - Nevan J Krogan
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, United States.,QB3, California Institute for Quantitative Biosciences, San Francisco, United States.,Gladstone Institutes, San Francisco, United States
| | - Joanne N Engel
- Department of Medicine, University of California, San Francisco, San Francisco, United States.,Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, United States
| | - Oren S Rosenberg
- Department of Medicine, University of California, San Francisco, San Francisco, United States
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30
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Paul B, Kim HS, Kerr MC, Huston WM, Teasdale RD, Collins BM. Structural basis for the hijacking of endosomal sorting nexin proteins by Chlamydia trachomatis. eLife 2017; 6. [PMID: 28226239 PMCID: PMC5348129 DOI: 10.7554/elife.22311] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Accepted: 02/19/2017] [Indexed: 12/17/2022] Open
Abstract
During infection chlamydial pathogens form an intracellular membrane-bound replicative niche termed the inclusion, which is enriched with bacterial transmembrane proteins called Incs. Incs bind and manipulate host cell proteins to promote inclusion expansion and provide camouflage against innate immune responses. Sorting nexin (SNX) proteins that normally function in endosomal membrane trafficking are a major class of inclusion-associated host proteins, and are recruited by IncE/CT116. Crystal structures of the SNX5 phox-homology (PX) domain in complex with IncE define the precise molecular basis for these interactions. The binding site is unique to SNX5 and related family members SNX6 and SNX32. Intriguingly the site is also conserved in SNX5 homologues throughout evolution, suggesting that IncE captures SNX5-related proteins by mimicking a native host protein interaction. These findings thus provide the first mechanistic insights both into how chlamydial Incs hijack host proteins, and how SNX5-related PX domains function as scaffolds in protein complex assembly.
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Affiliation(s)
- Blessy Paul
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Australia
| | - Hyun Sung Kim
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Australia
| | - Markus C Kerr
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Australia
| | | | - Rohan D Teasdale
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Australia
| | - Brett M Collins
- Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Australia
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31
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Sixt BS, Bastidas RJ, Finethy R, Baxter RM, Carpenter VK, Kroemer G, Coers J, Valdivia RH. The Chlamydia trachomatis Inclusion Membrane Protein CpoS Counteracts STING-Mediated Cellular Surveillance and Suicide Programs. Cell Host Microbe 2016; 21:113-121. [PMID: 28041929 DOI: 10.1016/j.chom.2016.12.002] [Citation(s) in RCA: 86] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Revised: 11/03/2016] [Accepted: 12/07/2016] [Indexed: 12/24/2022]
Abstract
Evading cell death is critical for Chlamydia to maintain a replicative niche, but the underlying mechanisms are unknown. We screened a library of Chlamydia mutants for modulators of cell death. Inactivation of the inclusion membrane protein CpoS (Chlamydia promoter of survival) induced rapid apoptotic and necrotic death in infected cells. The protection afforded by CpoS is limited to the inclusion in which it resides, indicating that it counteracts a spatially restricted pro-death signal. CpoS-deficient Chlamydia induced an exacerbated type I interferon response that required the host cGAS/STING/TBK1/IRF3 signaling pathway. Disruption of STING, but not cGAS or IRF3, attenuated cell death, suggesting that STING mediates Chlamydia-induced cell death independent of its role in regulating interferon responses. CpoS-deficient strains are attenuated in their ability to propagate in cell culture and are cleared faster from the murine genital tract, highlighting the importance of CpoS for Chlamydia pathogenesis.
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Affiliation(s)
- Barbara S Sixt
- Department of Molecular Genetics and Microbiology, Duke University, Durham, NC 27710, USA; INSERM U1138, Centre de Recherche des Cordeliers, Paris 75006, France; Equipe 11 labellisée Ligue Nationale contre le Cancer, Centre de Recherche des Cordeliers, Paris 75006, France; Université Paris Descartes, Paris 75006, France; Metabolomics and Cell Biology Platforms, Institut Gustave Roussy, Villejuif 94800, France
| | - Robert J Bastidas
- Department of Molecular Genetics and Microbiology, Duke University, Durham, NC 27710, USA
| | - Ryan Finethy
- Department of Molecular Genetics and Microbiology, Duke University, Durham, NC 27710, USA
| | - Ryan M Baxter
- Department of Molecular Genetics and Microbiology, Duke University, Durham, NC 27710, USA
| | - Victoria K Carpenter
- Department of Molecular Genetics and Microbiology, Duke University, Durham, NC 27710, USA
| | - Guido Kroemer
- INSERM U1138, Centre de Recherche des Cordeliers, Paris 75006, France; Equipe 11 labellisée Ligue Nationale contre le Cancer, Centre de Recherche des Cordeliers, Paris 75006, France; Université Paris Descartes, Paris 75006, France; Metabolomics and Cell Biology Platforms, Institut Gustave Roussy, Villejuif 94800, France; Pôle de Biologie, Hôpital Européen Georges-Pompidou, AP-HP, Paris 75015, France; Karolinska Institute, Department of Women's and Children's Health, Karolinska University Hospital, Stockholm 17176, Sweden
| | - Jörn Coers
- Department of Molecular Genetics and Microbiology, Duke University, Durham, NC 27710, USA; Department of Immunology, Duke University, Durham, NC 27710, USA
| | - Raphael H Valdivia
- Department of Molecular Genetics and Microbiology, Duke University, Durham, NC 27710, USA.
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32
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Tsai P, Hsu M, Huang C, Li S. Human Antibody and Antigen Response to INCA Antibody of Chlamydia Trachomatis. Int J Immunopathol Pharmacol 2016. [DOI: 10.1177/039463200702000118] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The high prevalence of C. trachomatis worldwide has underscored the importance of identifying specific immunogenic antigens in facilitating diagnosis as well as vaccine development The aim of this study is to evaluate IncA antibody and antigen production in natural human infections. Our temporal expression study showed that IncA transcription and protein expression could be detected as early as 4 hours after the start of infection. Antibody responses could be detected in urine and genital swab samples from C. trachomatis-positive patients. It is especially interesting to note that the IncA antigen could be detected in urine. In conclusion, we have identified IncA as an important antigen in human. The potential applicability of the IncA antibody or antigen in the diagnosis as well as to vaccine development for C. trachomatis is also discussed.
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Affiliation(s)
- P.Y. Tsai
- Mycotic Diseases Laboratory, Research and Diagnostics Center, Centers for Disease Control, Taipei
- Institute of Biopharmaceutical Sciences, National Yang-Ming University, Taipei, Taiwan
| | - M.C. Hsu
- Mycotic Diseases Laboratory, Research and Diagnostics Center, Centers for Disease Control, Taipei
| | - C.T. Huang
- Mycotic Diseases Laboratory, Research and Diagnostics Center, Centers for Disease Control, Taipei
| | - S.Y. Li
- Mycotic Diseases Laboratory, Research and Diagnostics Center, Centers for Disease Control, Taipei
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33
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Herweg JA, Pons V, Becher D, Hecker M, Krohne G, Barbier J, Berger H, Rudel T, Mehlitz A. Proteomic analysis of the Simkania-containing vacuole: the central role of retrograde transport. Mol Microbiol 2015; 99:151-71. [PMID: 26374382 DOI: 10.1111/mmi.13222] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/12/2015] [Indexed: 01/25/2023]
Abstract
Simkania negevensis is an obligate intracellular bacterial pathogen that grows in amoeba or human cells within a membrane-bound vacuole forming endoplasmic reticulum (ER) contact sites. The membrane of this Simkania-containing vacuole (SnCV) is a critical host-pathogen interface whose origin and molecular interactions with cellular organelles remain poorly defined. We performed proteomic analysis of purified ER-SnCV-membranes using label free LC-MS(2) to define the pathogen-containing organelle composition. Of the 1,178 proteins of human and 302 proteins of Simkania origin identified by this strategy, 51 host cell proteins were enriched or depleted by infection and 57 proteins were associated with host endosomal transport pathways. Chemical inhibitors that selectively interfere with trafficking at the early endosome-to-trans-Golgi network (TGN) interface (retrograde transport) affected SnCV formation, morphology and lipid transport. Our data demonstrate that Simkania exploits early endosome-to-TGN transport for nutrient acquisition and growth.
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Affiliation(s)
- Jo-Ana Herweg
- Department of Microbiology, University of Würzburg, Biocenter, Am Hubland, D-97074, Würzburg, Germany
| | - Valérie Pons
- DSV, iBiTec-S, LabEx LERMIT, CEA, F-91191, Gif sur Yvette, France
| | - Dörte Becher
- Department of Microbial Proteomics, University of Greifswald, Institute of Microbiology, Friedrich-Ludwig-Jahn-Straße 15, D-17487, Greifswald, Germany
| | - Michael Hecker
- Microbial Physiology/Molecular Biology, University of Greifswald, Institute of Microbiology, Friedrich-Ludwig-Jahn-Straße 15, D-17487, Greifswald, Germany
| | - Georg Krohne
- Division of Electron Microscopy, University of Würzburg, Biocenter, Am Hubland, D-97074, Würzburg, Germany
| | - Julien Barbier
- DSV, iBiTec-S, LabEx LERMIT, CEA, F-91191, Gif sur Yvette, France
| | - Hilmar Berger
- Department of Molecular Biology, Max-Planck-Institute for Infection Biology, Charitéplatz 1, D-10117, Berlin, Germany
| | - Thomas Rudel
- Department of Microbiology, University of Würzburg, Biocenter, Am Hubland, D-97074, Würzburg, Germany
| | - Adrian Mehlitz
- Department of Microbiology, University of Würzburg, Biocenter, Am Hubland, D-97074, Würzburg, Germany.,Department of Molecular Biology, Max-Planck-Institute for Infection Biology, Charitéplatz 1, D-10117, Berlin, Germany
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34
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Chlamydia trachomatis In Vivo to In Vitro Transition Reveals Mechanisms of Phase Variation and Down-Regulation of Virulence Factors. PLoS One 2015. [PMID: 26207372 PMCID: PMC4514472 DOI: 10.1371/journal.pone.0133420] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Research on the obligate intracellular bacterium Chlamydia trachomatis demands culture in cell-lines, but the adaptive process behind the in vivo to in vitro transition is not understood. We assessed the genomic and transcriptomic dynamics underlying C. trachomatis in vitro adaptation of strains representing the three disease groups (ocular, epithelial-genital and lymphogranuloma venereum) propagated in epithelial cells over multiple passages. We found genetic features potentially underlying phase variation mechanisms mediating the regulation of a lipid A biosynthesis enzyme (CT533/LpxC), and the functionality of the cytotoxin (CT166) through an ON/OFF mechanism. We detected inactivating mutations in CT713/porB, a scenario suggesting metabolic adaptation to the available carbon source. CT135 was inactivated in a tropism-specific manner, with CT135-negative clones emerging for all epithelial-genital populations (but not for LGV and ocular populations) and rapidly increasing in frequency (~23% mutants per 10 passages). RNA-sequencing analyses revealed that a deletion event involving CT135 impacted the expression of multiple virulence factors, namely effectors known to play a role in the C. trachomatis host-cell invasion or subversion (e.g., CT456/Tarp, CT694, CT875/TepP and CT868/ChlaDub1). This reflects a scenario of attenuation of C. trachomatis virulence in vitro, which may take place independently or in a cumulative fashion with the also observed down-regulation of plasmid-related virulence factors. This issue may be relevant on behalf of the recent advances in Chlamydia mutagenesis and transformation where culture propagation for selecting mutants/transformants is mandatory. Finally, there was an increase in the growth rate for all strains, reflecting gradual fitness enhancement over time. In general, these data shed light on the adaptive process underlying the C. trachomatis in vivo to in vitro transition, and indicates that it would be prudent to restrict culture propagation to minimal passages and check the status of the CT135 genotype in order to avoid the selection of CT135-negative mutants, likely originating less virulent strains.
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Mirrashidi KM, Elwell CA, Verschueren E, Johnson JR, Frando A, Von Dollen J, Rosenberg O, Gulbahce N, Jang G, Johnson T, Jäger S, Gopalakrishnan AM, Sherry J, Dunn JD, Olive A, Penn B, Shales M, Cox JS, Starnbach MN, Derre I, Valdivia R, Krogan NJ, Engel J. Global Mapping of the Inc-Human Interactome Reveals that Retromer Restricts Chlamydia Infection. Cell Host Microbe 2015; 18:109-21. [PMID: 26118995 DOI: 10.1016/j.chom.2015.06.004] [Citation(s) in RCA: 138] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Revised: 04/28/2015] [Accepted: 06/05/2015] [Indexed: 01/02/2023]
Abstract
Chlamydia trachomatis is a leading cause of genital and ocular infections for which no vaccine exists. Upon entry into host cells, C. trachomatis resides within a membrane-bound compartment—the inclusion—and secretes inclusion membrane proteins (Incs) that are thought to modulate the host-bacterium interface. To expand our understanding of Inc function(s), we subjected putative C. trachomatis Incs to affinity purification-mass spectroscopy (AP-MS). We identified Inc-human interactions for 38/58 Incs with enrichment in host processes consistent with Chlamydia's intracellular life cycle. There is significant overlap between Inc targets and viral proteins, suggesting common pathogenic mechanisms among obligate intracellular microbes. IncE binds to sorting nexins (SNXs) 5/6, components of the retromer, which relocalizes SNX5/6 to the inclusion membrane and augments inclusion membrane tubulation. Depletion of retromer components enhances progeny production, revealing that retromer restricts Chlamydia infection. This study demonstrates the value of proteomics in unveiling host-pathogen interactions in genetically challenging microbes.
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Affiliation(s)
- Kathleen M Mirrashidi
- Department of Medicine, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Cherilyn A Elwell
- Department of Medicine, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Erik Verschueren
- QB3, California Institute for Quantitative Biosciences, San Francisco, CA 94148, USA; Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Jeffrey R Johnson
- QB3, California Institute for Quantitative Biosciences, San Francisco, CA 94148, USA; Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Andrew Frando
- Department of Medicine, University of California, San Francisco, San Francisco, CA 94143, USA
| | - John Von Dollen
- QB3, California Institute for Quantitative Biosciences, San Francisco, CA 94148, USA; Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Oren Rosenberg
- Department of Medicine, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Natali Gulbahce
- QB3, California Institute for Quantitative Biosciences, San Francisco, CA 94148, USA; Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Gwendolyn Jang
- QB3, California Institute for Quantitative Biosciences, San Francisco, CA 94148, USA; Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Tasha Johnson
- QB3, California Institute for Quantitative Biosciences, San Francisco, CA 94148, USA; Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Stefanie Jäger
- QB3, California Institute for Quantitative Biosciences, San Francisco, CA 94148, USA; Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158, USA
| | | | - Jessica Sherry
- Department of Medicine, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Joe Dan Dunn
- Department of Molecular Genetics and Microbiology, Duke University, Durham, NC 27710, USA
| | - Andrew Olive
- Department of Microbiology, Harvard Medical School, Boston, MA 02115, USA
| | - Bennett Penn
- Department of Medicine, University of California, San Francisco, San Francisco, CA 94143, USA
| | - Michael Shales
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158, USA; Gladstone Institutes, San Francisco, CA 94158, USA
| | - Jeffery S Cox
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA 94143, USA
| | | | - Isabelle Derre
- Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, CT 06510, USA
| | - Raphael Valdivia
- Department of Molecular Genetics and Microbiology, Duke University, Durham, NC 27710, USA
| | - Nevan J Krogan
- QB3, California Institute for Quantitative Biosciences, San Francisco, CA 94148, USA; Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94158, USA; Gladstone Institutes, San Francisco, CA 94158, USA.
| | - Joanne Engel
- Department of Medicine, University of California, San Francisco, San Francisco, CA 94143, USA; Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA 94143, USA.
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The Chlamydia pneumoniae Inclusion Membrane Protein Cpn1027 Interacts with Host Cell Wnt Signaling Pathway Regulator Cytoplasmic Activation/Proliferation-Associated Protein 2 (Caprin2). PLoS One 2015; 10:e0127909. [PMID: 25996495 PMCID: PMC4440618 DOI: 10.1371/journal.pone.0127909] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Accepted: 04/21/2015] [Indexed: 11/19/2022] Open
Abstract
We previously identified hypothetical protein Cpn1027 as a novel inclusion membrane protein that is unique to Chlamydia pneumoniae. In the current study, using a yeast-two hybrid screen assay, we identified host cell cytoplasmic activation/proliferation-associated protein 2 (Caprin2) as an interacting partner of Cpn1027. The interaction was confirmed and mapped to the C-termini of both Cpn1027 and Caprin2 using co-immunoprecipitation and GST pull-down assays. A RFP-Caprin2 fusion protein was recruited to the chlamydial inclusion and so was the endogenous GSK3β, a critical component of the β-catenin destruction complex in the Wnt signaling pathway. Cpn1027 also co-precipitated GSK3β. Caprin2 is a key regulator of the Wnt signaling pathway by promoting the recruitment of the β-catenin destruction complex to the cytoplasmic membrane in the presence of Wnt signaling while GSK3β is required for priming β-catenin for degradation in the absence of Wnt signaling. The Cpn1027 interactions with Caprin2 and GSK3β may allow C. pneumoniae to actively sequester the β-catenin destruction complex so that β-catenin is maintained even in the absence of extracellular Wnt activation signals. The maintained β-catenin can trans-activate Wnt target genes including Bcl-2, which may contribute to the chlamydial antiapoptotic activity. We found that the C. pneumoniae-infected cells were more resistant to apoptosis induction and the anti-apoptotic activity was dependent on β-catenin. Thus, the current study suggests that the chlamydial inclusion protein Cpn1027 may be able to manipulate host Wnt signaling pathway for enhancing the chlamydial anti-apoptotic activity.
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Borges V, Gomes JP. Deep comparative genomics among Chlamydia trachomatis lymphogranuloma venereum isolates highlights genes potentially involved in pathoadaptation. INFECTION GENETICS AND EVOLUTION 2015; 32:74-88. [PMID: 25745888 DOI: 10.1016/j.meegid.2015.02.026] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Revised: 02/23/2015] [Accepted: 02/26/2015] [Indexed: 11/19/2022]
Abstract
Lymphogranuloma venereum (LGV) is a human sexually transmitted disease caused by the obligate intracellular bacterium Chlamydia trachomatis (serovars L1-L3). LGV clinical manifestations range from severe ulcerative proctitis (anorectal syndrome), primarily caused by the epidemic L2b strains, to painful inguinal lymphadenopathy (the typical LGV bubonic form). Besides potential host-related factors, the differential disease severity and tissue tropism among LGV strains is likely a function of the genetic backbone of the strains. We aimed to characterize the genetic variability among LGV strains as strain- or serovar-specific mutations may underlie phenotypic signatures, and to investigate the mutational events that occurred throughout the pathoadaptation of the epidemic L2b lineage. By analyzing 20 previously published genomes from L1, L2, L2b and L3 strains and two new genomes from L2b strains, we detected 1497 variant sites and about 100 indels, affecting 453 genes and 144 intergenic regions, with 34 genes displaying a clear overrepresentation of nonsynonymous mutations. Effectors and/or type III secretion substrates (almost all of those described in the literature) and inclusion membrane proteins showed amino acid changes that were about fivefold more frequent than silent changes. More than 120 variant sites occurred in plasmid-regulated virulence genes, and 66% yielded amino acid changes. The identified serovar-specific variant sites revealed that the L2b-specific mutations are likely associated with higher fitness and pointed out potential targets for future highly discriminatory diagnostic/typing tests. By evaluating the evolutionary pathway beyond the L2b clonal radiation, we observed that 90.2% of the intra-L2b variant sites occurring in coding regions involve nonsynonymous mutations, where CT456/tarp has been the main target. Considering the progress on C. trachomatis genetic manipulation, this study may constitute an important contribution for prioritizing study targets for functional genomics aiming to dissect the impact of the identified intra-LGV polymorphisms on virulence or tropism dissimilarities among LGV strains.
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Affiliation(s)
- Vítor Borges
- Reference Laboratory of Bacterial Sexually Transmitted Infections, Department of Infectious Diseases, National Institute of Health, Av. Padre Cruz, 1649-016 Lisbon, Portugal; Bioinformatics Unit, Department of Infectious Diseases, National Institute of Health, Av. Padre Cruz, 1649-016 Lisbon, Portugal
| | - João Paulo Gomes
- Reference Laboratory of Bacterial Sexually Transmitted Infections, Department of Infectious Diseases, National Institute of Health, Av. Padre Cruz, 1649-016 Lisbon, Portugal; Bioinformatics Unit, Department of Infectious Diseases, National Institute of Health, Av. Padre Cruz, 1649-016 Lisbon, Portugal.
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Ronzone E, Wesolowski J, Bauler LD, Bhardwaj A, Hackstadt T, Paumet F. An α-helical core encodes the dual functions of the chlamydial protein IncA. J Biol Chem 2014; 289:33469-80. [PMID: 25324548 DOI: 10.1074/jbc.m114.592063] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Chlamydia is an intracellular bacterium that establishes residence within parasitophorous compartments (inclusions) inside host cells. Chlamydial inclusions are uncoupled from the endolysosomal pathway and undergo fusion with cellular organelles and with each other. To do so, Chlamydia expresses proteins on the surface of the inclusion using a Type III secretion system. These proteins, termed Incs, are located at the interface between host and pathogen and carry out the functions necessary for Chlamydia survival. Among these Incs, IncA plays a critical role in both protecting the inclusion from lysosomal fusion and inducing the homotypic fusion of inclusions. Within IncA are two regions homologous to eukaryotic SNARE (soluble N-ethylmaleimide-sensitive factor attachment receptor) domains referred to as SNARE-like domain 1 (SLD1) and SNARE-like domain 2 (SLD2). Using a multidisciplinary approach, we have discovered the functional core of IncA that retains the ability to both inhibit SNARE-mediated fusion and promote the homotypic fusion of Chlamydia inclusions. Circular dichroism and analytical ultracentrifugation experiments show that this core region is composed almost entirely of α-helices and assembles into stable homodimers in solution. Altogether, we propose that both IncA functions are encoded in a structured core domain that encompasses SLD1 and part of SLD2.
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Affiliation(s)
- Erik Ronzone
- From the Departments of Microbiology and Immunology and
| | | | - Laura D Bauler
- the Host-Parasite Interactions Section, Laboratory of Intracellular Parasites, Rocky Mountain Laboratories, NIAID, National Institutes of Health, Hamilton, Montana 59840
| | - Anshul Bhardwaj
- Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107 and
| | - Ted Hackstadt
- the Host-Parasite Interactions Section, Laboratory of Intracellular Parasites, Rocky Mountain Laboratories, NIAID, National Institutes of Health, Hamilton, Montana 59840
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Omsland A, Sixt BS, Horn M, Hackstadt T. Chlamydial metabolism revisited: interspecies metabolic variability and developmental stage-specific physiologic activities. FEMS Microbiol Rev 2014; 38:779-801. [PMID: 24484402 DOI: 10.1111/1574-6976.12059] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Revised: 01/08/2014] [Accepted: 01/13/2014] [Indexed: 01/07/2023] Open
Abstract
Chlamydiae are a group of obligate intracellular bacteria comprising important human and animal pathogens as well as symbionts of ubiquitous protists. They are characterized by a developmental cycle including two main morphologically and physiologically distinct stages, the replicating reticulate body and the infectious nondividing elementary body. In this review, we reconstruct the history of studies that have led to our current perception of chlamydial physiology, focusing on their energy and central carbon metabolism. We then compare the metabolic capabilities of pathogenic and environmental chlamydiae highlighting interspecies variability among the metabolically more flexible environmental strains. We discuss recent findings suggesting that chlamydiae may not live as energy parasites throughout the developmental cycle and that elementary bodies are not metabolically inert but exhibit metabolic activity under appropriate axenic conditions. The observed host-free metabolic activity of elementary bodies may reflect adequate recapitulation of the intracellular environment, but there is evidence that this activity is biologically relevant and required for extracellular survival and maintenance of infectivity. The recent discoveries call for a reconsideration of chlamydial metabolism and future in-depth analyses to better understand how species- and stage-specific differences in chlamydial physiology may affect virulence, tissue tropism, and host adaptation.
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Affiliation(s)
- Anders Omsland
- Host-Parasite Interactions Section, Laboratory of Intracellular Parasites, NIAID, NIH, Hamilton, MT, USA
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Chen YS, Bastidas RJ, Saka HA, Carpenter VK, Richards KL, Plano GV, Valdivia RH. The Chlamydia trachomatis type III secretion chaperone Slc1 engages multiple early effectors, including TepP, a tyrosine-phosphorylated protein required for the recruitment of CrkI-II to nascent inclusions and innate immune signaling. PLoS Pathog 2014; 10:e1003954. [PMID: 24586162 PMCID: PMC3930595 DOI: 10.1371/journal.ppat.1003954] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Accepted: 01/10/2014] [Indexed: 02/06/2023] Open
Abstract
Chlamydia trachomatis, the causative agent of trachoma and sexually transmitted infections, employs a type III secretion (T3S) system to deliver effector proteins into host epithelial cells to establish a replicative vacuole. Aside from the phosphoprotein TARP, a Chlamydia effector that promotes actin re-arrangements, very few factors mediating bacterial entry and early inclusion establishment have been characterized. Like many T3S effectors, TARP requires a chaperone (Slc1) for efficient translocation into host cells. In this study, we defined proteins that associate with Slc1 in invasive C. trachomatis elementary bodies (EB) by immunoprecipitation coupled with mass spectrometry. We identified Ct875, a new Slc1 client protein and T3S effector, which we renamed TepP (Translocated early phosphoprotein). We provide evidence that T3S effectors form large molecular weight complexes with Scl1 in vitro and that Slc1 enhances their T3S-dependent secretion in a heterologous Yersinia T3S system. We demonstrate that TepP is translocated early during bacterial entry into epithelial cells and is phosphorylated at tyrosine residues by host kinases. However, TepP phosphorylation occurs later than TARP, which together with the finding that Slc1 preferentially engages TARP in EBs leads us to postulate that these effectors are translocated into the host cell at different stages during C. trachomatis invasion. TepP co-immunoprecipitated with the scaffolding proteins CrkI-II during infection and Crk was recruited to EBs at entry sites where it remained associated with nascent inclusions. Importantly, C. trachomatis mutants lacking TepP failed to recruit CrkI-II to inclusions, providing genetic confirmation of a direct role for this effector in the recruitment of a host factor. Finally, endocervical epithelial cells infected with a tepP mutant showed altered expression of a subset of genes associated with innate immune responses. We propose a model wherein TepP acts downstream of TARP to recruit scaffolding proteins at entry sites to initiate and amplify signaling cascades important for the regulation of innate immune responses to Chlamydia.
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Affiliation(s)
- Yi-Shan Chen
- Department of Molecular Genetics and Microbiology and Center for Microbial Pathogenesis, Duke University Medical Center, Durham, North Carolina, United States of America
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Robert J. Bastidas
- Department of Molecular Genetics and Microbiology and Center for Microbial Pathogenesis, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Hector A. Saka
- Department of Molecular Genetics and Microbiology and Center for Microbial Pathogenesis, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Victoria K. Carpenter
- Department of Molecular Genetics and Microbiology and Center for Microbial Pathogenesis, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Kristian L. Richards
- Department of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, Florida, United States of America
| | - Gregory V. Plano
- Department of Microbiology and Immunology, University of Miami Miller School of Medicine, Miami, Florida, United States of America
| | - Raphael H. Valdivia
- Department of Molecular Genetics and Microbiology and Center for Microbial Pathogenesis, Duke University Medical Center, Durham, North Carolina, United States of America
- * E-mail:
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Lu C, Lei L, Peng B, Tang L, Ding H, Gong S, Li Z, Wu Y, Zhong G. Chlamydia trachomatis GlgA is secreted into host cell cytoplasm. PLoS One 2013; 8:e68764. [PMID: 23894341 PMCID: PMC3722199 DOI: 10.1371/journal.pone.0068764] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2012] [Accepted: 06/04/2013] [Indexed: 12/03/2022] Open
Abstract
Glycogen has been localized both inside and outside Chlamydia trachomatis organisms. We now report that C. trachomatis glycogen synthase (GlgA) was detected in both chlamydial organism-associated and -free forms. The organism-free GlgA molecules were localized both in the lumen of chlamydial inclusions and in the cytosol of host cells. The cytosolic GlgA displayed a distribution pattern similar to that of a known C. trachomatis-secreted protease, CPAF. The detection of GlgA was specific since the anti-GlgA antibody labeling was only removed by preabsorption with GlgA but not CPAF fusion proteins. GlgA was detectable at 12h and its localization into host cell cytosol only became apparent at 24h after infection. The cytosolic localization of GlgA was conserved among all C. trachomatis serovars. However, the significance of the GlgA secretion into host cell cytoplasm remains unclear since, while expression of chlamydial GlgA in HeLa cells increased glycogen stores, it did not affect a subsequent infection with C. trachomatis. Similar to several other C. trachomatis-secreted proteins, GlgA is immunogenic in women urogenitally infected with C. trachomatis, suggesting that GlgA is expressed and may be secreted into host cell cytosol during C. trachomatis infection in humans. These findings have provided important information for further understanding C. trachomatis pathogenic mechanisms.
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Affiliation(s)
- Chunxue Lu
- Department of Pathogen Biology, University of South China, Hengyang, Hunan, China
- Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Lei Lei
- Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Bo Peng
- Department of Pathogen Biology, University of South China, Hengyang, Hunan, China
- Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Lingli Tang
- Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Honglei Ding
- Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Siqi Gong
- Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
| | - Zhongyu Li
- Department of Pathogen Biology, University of South China, Hengyang, Hunan, China
| | - Yimou Wu
- Department of Pathogen Biology, University of South China, Hengyang, Hunan, China
- * E-mail: (YW); (GZ)
| | - Guangming Zhong
- Department of Microbiology and Immunology, University of Texas Health Science Center at San Antonio, San Antonio, Texas, United States of America
- * E-mail: (YW); (GZ)
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Assessing a potential role of host Pannexin 1 during Chlamydia trachomatis infection. PLoS One 2013; 8:e63732. [PMID: 23700432 PMCID: PMC3659042 DOI: 10.1371/journal.pone.0063732] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2013] [Accepted: 04/04/2013] [Indexed: 01/08/2023] Open
Abstract
Pannexin 1 (Panx1) is a plasma membrane channel glycoprotein that plays a role in innate immune response through association with the inflammasome complex. Probenecid, a classic pharmacological agent for gout, has also been used historically in combination therapy with antibiotics to prevent cellular drug efflux and has been reported to inhibit Panx1. As the inflammasome has been implicated in the progression of Chlamydia infections, and with chlamydial infections at record levels in the US, we therefore investigated whether probenecid would have a direct effect on Chlamydia trachomatis development through inhibition of Panx1. We found chlamydial development to be inhibited in a dose-dependent, yet reversible manner in the presence of probenecid. Drug treatment induced an aberrant chlamydial morphology consistent with persistent bodies. Although Panx1 was shown to localize to the chlamydial inclusion, no difference was seen in chlamydial development during infection of cells derived from wild-type and Panx1 knockout mice. Therefore, probenecid may inhibit C. trachomatis growth by an as yet unresolved mechanism.
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Role for chlamydial inclusion membrane proteins in inclusion membrane structure and biogenesis. PLoS One 2013; 8:e63426. [PMID: 23696825 PMCID: PMC3656976 DOI: 10.1371/journal.pone.0063426] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2013] [Accepted: 04/02/2013] [Indexed: 11/20/2022] Open
Abstract
The chlamydial inclusion membrane is extensively modified by the insertion of type III secreted effector proteins. These inclusion membrane proteins (Incs) are exposed to the cytosol and share a common structural feature of a long, bi-lobed hydrophobic domain but little or no primary amino acid sequence similarity. Based upon secondary structural predictions, over 50 putative inclusion membrane proteins have been identified in Chlamydia trachomatis. Only a limited number of biological functions have been defined and these are not shared between chlamydial species. Here we have ectopically expressed several C. trachomatis Incs in HeLa cells and find that they induce the formation of morphologically distinct membranous vesicular compartments. Formation of these vesicles requires the bi-lobed hydrophobic domain as a minimum. No markers for various cellular organelles were observed in association with these vesicles. Lipid probes were incorporated by the Inc-induced vesicles although the lipids incorporated were dependent upon the specific Inc expressed. Co-expression of Inc pairs indicated that some colocalized in the same vesicle, others partially overlapped, and others did not associate at all. Overall, it appears that Incs may have an intrinsic ability to induce membrane formation and that individual Incs can induce membranous structures with unique properties.
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Characterizing the intracellular distribution of metabolites in intact Chlamydia-infected cells by Raman and two-photon microscopy. Microbes Infect 2013; 15:461-9. [PMID: 23541981 DOI: 10.1016/j.micinf.2013.03.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Revised: 02/17/2013] [Accepted: 03/17/2013] [Indexed: 11/24/2022]
Abstract
Chlamydia species are obligate intracellular pathogens that proliferate only within infected cells. Currently, there are no known techniques or systems that can probe the spatial distribution of metabolites of interest within intact Chlamydia-infected cells. Here we investigate the ability of Raman microscopy to probe the chemical composition of different compartments (nucleus, inclusion, and cytoplasm) of Chlamydia trachomatis-infected epithelial cells. The overall intensity of the Raman spectrum is greatest in the inclusions and lowest in the cytoplasm in fixed cells. Difference spectra generated by normalizing to the intensity of the strong 1004 cm(-1) phenylalanine line show distinct differences among the three compartments. Most notably, the concentrations of adenine are greater in both the inclusions and the nucleus than in the cytoplasm, as seen by Raman microscopy. The source of the adenine was explored through a complementary approach, using two-photon microscopy imaging. Autofluorescence measurements of living, infected cells show that the adenine-containing molecules, NAD(P)H and FAD, are present mainly in the cytoplasm, suggesting that these molecules are not the source of the additional adenine signal in the nucleus and inclusions. Experiments of infected cells stained with a DNA-binding dye, Hoechst 33258, reveal that most of the DNA is present in the nucleus and the inclusions, suggesting that DNA/RNA is the main source of the additional Raman adenine signal in the nucleus and inclusions. Thus, Raman and two-photon microscopy are among the few non-invasive methods available to investigate cells infected with Chlamydia and, together, should also be useful for studying infection by other intracellular pathogens that survive within intracellular vacuoles.
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Beeckman DS, De Puysseleyr L, De Puysseleyr K, Vanrompay D. Chlamydial biology and its associated virulence blockers. Crit Rev Microbiol 2012; 40:313-28. [PMID: 23134414 DOI: 10.3109/1040841x.2012.726210] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Chlamydiales are obligate intracellular parasites of eukaryotic cells. They can be distinguished from other Gram-negative bacteria through their characteristic developmental cycle, in addition to special biochemical and physical adaptations to subvert the eukaryotic host cell. The host spectrum includes humans and other mammals, fish, birds, reptiles, insects and even amoeba, causing a plethora of diseases. The first part of this review focuses on the specific chlamydial infection biology and metabolism. As resistance to classical antibiotics is emerging among Chlamydiae as well, the second part elaborates on specific compounds and tools to block chlamydial virulence traits, such as adhesion and internalization, Type III secretion and modulation of gene expression.
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Affiliation(s)
- Delphine S Beeckman
- Department of Molecular Biotechnology, Faculty of Bioscience Engineering, Ghent University , Coupure Links 653, B-9000 Ghent , Belgium
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Polymorphisms in inc proteins and differential expression of inc genes among Chlamydia trachomatis strains correlate with invasiveness and tropism of lymphogranuloma venereum isolates. J Bacteriol 2012; 194:6574-85. [PMID: 23042990 DOI: 10.1128/jb.01428-12] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Chlamydia trachomatis is a human bacterial pathogen that multiplies only within an intracellular membrane-bound vacuole, the inclusion. C. trachomatis includes ocular and urogenital strains, usually causing infections restricted to epithelial cells of the conjunctiva and genital mucosa, respectively, and lymphogranuloma venereum (LGV) strains, which can infect macrophages and spread into lymph nodes. However, C. trachomatis genomes display >98% identity at the DNA level. In this work, we studied whether C. trachomatis Inc proteins, which have a bilobed hydrophobic domain that may mediate their insertion in the inclusion membrane, could be a factor determining these different types of infection and tropisms. Analyses of polymorphisms and phylogeny of 48 Inc proteins from 51 strains encompassing the three disease groups showed significant amino acid differences that were mainly due to variations between Inc proteins from LGV and ocular or urogenital isolates. Studies of the evolutionary dynamics of inc genes suggested that 10 of them are likely under positive selection and indicated that most nonsilent mutations are LGV specific. Additionally, real-time quantitative PCR analyses in prototype and clinical strains covering the three disease groups identified three inc genes with LGV-specific expression. We determined the transcriptional start sites of these genes and found LGV-specific nucleotides within their promoters. Thus, subtle variations in the amino acids of a subset of Inc proteins and in the expression of inc genes may contribute to the unique tropism and invasiveness of C. trachomatis LGV strains.
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47
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Reversible inhibition of Chlamydia trachomatis infection in epithelial cells due to stimulation of P2X(4) receptors. Infect Immun 2012; 80:4232-8. [PMID: 22988022 DOI: 10.1128/iai.00441-12] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Bacterial infections of the mucosal epithelium are a major cause of human disease. The prolonged presence of microbial pathogens stimulates inflammation of the local tissues, which leads to changes in the molecular composition of the extracellular milieu. A well-characterized molecule that is released to the extracellular milieu by stressed or infected cells is extracellular ATP and its ecto-enzymatic degradation products, which function as signaling molecules through ligation of purinergic receptors. There has been little information, however, on the effects of the extracellular metabolites on bacterial growth in inflamed tissues. Millimolar concentrations of ATP have been previously shown to inhibit irreversibly bacterial infection through ligation of P2X(7) receptors. We show here that the proinflammatory mediator, ATP, is released from Chlamydia trachomatis-infected epithelial cells. Moreover, further stimulation of the infected cells with micromolar extracellular ADP or ATP significantly impairs the growth of the bacteria, with a profile characteristic of the involvement of P2X(4) receptors. A specific role for P2X(4) was confirmed using cells overexpressing P2X(4). The chlamydiae remain viable and return to normal growth kinetics after removal of the extracellular stimulus, similar to responses previously described for persistence of chlamydial infection.
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Directional evolution of Chlamydia trachomatis towards niche-specific adaptation. J Bacteriol 2012; 194:6143-53. [PMID: 22961851 DOI: 10.1128/jb.01291-12] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
On behalf of the host-pathogen "arms race," a cutting-edge approach for elucidating genotype-phenotype relationships relies on the identification of positively selected loci involved in pathoadaptation. We studied the obligate intracellular bacterium Chlamydia trachomatis, for which same-species strains display a nearly identical core and pan genome, while presenting a wide range of tissue tropism and ecological success. We sought to evaluate the evolutionary patterns underlying species separation (divergence) and C. trachomatis serovar radiation (polymorphism) and to establish genotype-phenotype associations. By analyzing 60 Chlamydia strains, we detected traces of Muller's ratchet as a result of speciation and identified positively selected genes and codons hypothetically involved in the infection of different human cell types (e.g., columnar epithelial cells of ocular or genital mucosae and mononuclear phagocytes) and also events likely driving pathogenic and ecological success dissimilarities. In general, these genes code for proteins involved in immune response elicitation, proteolysis, and the subversion of host-cell functions, and also for proteins with unknown function(s). Several genes are potentially involved in more than one adaptive process, suggesting multiple functions or a distinct modus operandi for a specific function, and thus should be considered as crucial research targets. In addition, six of the nine genes encoding the putative antigen/adhesin polymorphic membrane proteins seem to be under positive selection along specific serovars, which sustains an essential biological role of this extra-large paralogue family in chlamydial pathobiology. This study provides insight into how evolutionary inferences illuminate ecological processes such as adaptation to different niches, pathogenicity, or ecological success driven by arms races.
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Sun HS, Eng EWY, Jeganathan S, Sin ATW, Patel PC, Gracey E, Inman RD, Terebiznik MR, Harrison RE. Chlamydia trachomatis vacuole maturation in infected macrophages. J Leukoc Biol 2012; 92:815-27. [PMID: 22807527 DOI: 10.1189/jlb.0711336] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Chlamydia trachomatis is an obligate intracellular bacterium responsible for one of the most common sexually transmitted diseases. In epithelial cells, C. trachomatis resides in a modified membrane-bound vacuole known as an inclusion, which is isolated from the endocytic pathway. However, the maturation process of C. trachomatis within immune cells, such as macrophages, has not been studied extensively. Here, we demonstrated that RAW macrophages effectively suppressed C. trachomatis growth and prevented Golgi stack disruption, a hallmark defect in epithelial cells after C. trachomatis infection. Next, we systematically examined association between C. trachomatis and various endocytic pathway markers. Spinning disk confocal time-lapse studies revealed significant and rapid association between C. trachomatis with Rab7 and LAMP1, markers of late endosomes and lysosomes. Moreover, pretreatment with an inhibitor of lysosome acidification led to significant increases in C. trachomatis growth in macrophages. At later stages of infection, C. trachomatis associated with the autophagy marker LC3. TEM analysis confirmed that a significant portion of C. trachomatis resided within double-membrane-bound compartments, characteristic of autophagosomes. Together, these results suggest that macrophages can suppress C. trachomatis growth by targeting it rapidly to lysosomes; moreover, autophagy is activated at later stages of infection and targets significant numbers of the invading bacteria, which may enhance subsequent chlamydial antigen presentation.
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Affiliation(s)
- He Song Sun
- Departments of Cell and Systems Biology and Biological Sciences, University of Toronto Scarborough, Ontario, Canada
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Distinct intensity of host-pathogen interactions in Chlamydia psittaci- and Chlamydia abortus-infected chicken embryos. Infect Immun 2012; 80:2976-88. [PMID: 22689815 DOI: 10.1128/iai.00437-12] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Factors and mechanisms determining the differences in virulence and host specificity between the zoonotic agents Chlamydia psittaci and Chlamydia abortus are still largely unknown. In the present study, two strains were compared for their invasiveness, virulence, and capability of eliciting an immune response in chicken embryos. On breeding day 10, embryonated chicken eggs were inoculated with 5 × 10(4) inclusion-forming units. As shown by immunohistochemistry and quantitative real-time PCR, C. psittaci displayed a significantly better capability of disseminating in the chorioallantoic membrane (CAM) and internal organs than C. abortus. The higher infectious potential of C. psittaci in birds was underlined by significantly higher mRNA expression rates of essential chlamydial genes, such as incA, groEL (in CAM, liver, and spleen), cpaf, and ftsW (in CAM). Although the immune responses to both pathogens were similar, C. psittaci elicited higher macrophage numbers and a stronger expression of a subset of immune-related proteins. The data imply that invasiveness of Chlamydia spp. and propagation in the host are not solely dependent on the level of host immune response but, even to a greater extent, on the expression of bacterial factors related to virulence. The fact that C. psittaci has coped far better than C. abortus with the avian embryo's response by upregulating essential genes may be a key to understanding the mechanisms underlying host adaptation and etiopathology.
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