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Li K, Chatterjee A, Qian C, Lagree K, Wang Y, Becker CA, Freeman MR, Murali R, Yang W, Underhill DM. Profiling phagosome proteins identifies PD-L1 as a fungal-binding receptor. Nature 2024; 630:736-743. [PMID: 38839956 DOI: 10.1038/s41586-024-07499-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Accepted: 05/01/2024] [Indexed: 06/07/2024]
Abstract
Phagocytosis is the process by which myeloid phagocytes bind to and internalize potentially dangerous microorganisms1. During phagocytosis, innate immune receptors and associated signalling proteins are localized to the maturing phagosome compartment, forming an immune information processing hub brimming with microorganism-sensing features2-8. Here we developed proximity labelling of phagosomal contents (PhagoPL) to identify proteins localizing to phagosomes containing model yeast and bacteria. By comparing the protein composition of phagosomes containing evolutionarily and biochemically distinct microorganisms, we unexpectedly identified programmed death-ligand 1 (PD-L1) as a protein that specifically enriches in phagosomes containing yeast. We found that PD-L1 directly binds to yeast upon processing in phagosomes. By surface display library screening, we identified the ribosomal protein Rpl20b as a fungal protein ligand for PD-L1. Using an auxin-inducible depletion system, we found that detection of Rpl20b by macrophages cross-regulates production of distinct cytokines including interleukin-10 (IL-10) induced by the activation of other innate immune receptors. Thus, this study establishes PhagoPL as a useful approach to quantifying the collection of proteins enriched in phagosomes during host-microorganism interactions, exemplified by identifying PD-L1 as a receptor that binds to fungi.
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Affiliation(s)
- Kai Li
- Department of Biomedical Sciences, Division of Immunology, Cedars-Sinai Medical Center, Los Angeles, CA, USA.
- F. Widjaja Inflammatory Bowel Disease Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA.
| | - Avradip Chatterjee
- Department of Biomedical Sciences, Division of Immunology, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Chen Qian
- Department of Urology, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Katherine Lagree
- Department of Biomedical Sciences, Division of Immunology, Cedars-Sinai Medical Center, Los Angeles, CA, USA
- F. Widjaja Inflammatory Bowel Disease Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Yang Wang
- Department of Biomedical Sciences, Division Cancer Biology and Therapeutics, Cedars-Sinai Medical Center, Los Angeles, CA, USA
- Department of Surgery, Cedars-Sinai Medical Center, Los Angeles, CA, USA
- Samuel Oschin Comprehensive Cancer Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Courtney A Becker
- F. Widjaja Inflammatory Bowel Disease Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Michael R Freeman
- Department of Urology, Cedars-Sinai Medical Center, Los Angeles, CA, USA
- Department of Biomedical Sciences, Division Cancer Biology and Therapeutics, Cedars-Sinai Medical Center, Los Angeles, CA, USA
- Samuel Oschin Comprehensive Cancer Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Ramachandran Murali
- Department of Biomedical Sciences, Division of Immunology, Cedars-Sinai Medical Center, Los Angeles, CA, USA
- Samuel Oschin Comprehensive Cancer Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - Wei Yang
- Department of Biomedical Sciences, Division Cancer Biology and Therapeutics, Cedars-Sinai Medical Center, Los Angeles, CA, USA
- Department of Surgery, Cedars-Sinai Medical Center, Los Angeles, CA, USA
- Samuel Oschin Comprehensive Cancer Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA
| | - David M Underhill
- Department of Biomedical Sciences, Division of Immunology, Cedars-Sinai Medical Center, Los Angeles, CA, USA.
- F. Widjaja Inflammatory Bowel Disease Institute, Cedars-Sinai Medical Center, Los Angeles, CA, USA.
- Department of Medicine, Karsh Division of Gastroenterology and Hepatology, Cedars-Sinai Medical Center, Los Angeles, CA, USA.
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2
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Chandrasekharan G, Unnikrishnan M. High throughput methods to study protein-protein interactions during host-pathogen interactions. Eur J Cell Biol 2024; 103:151393. [PMID: 38306772 DOI: 10.1016/j.ejcb.2024.151393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2023] [Revised: 01/18/2024] [Accepted: 01/21/2024] [Indexed: 02/04/2024] Open
Abstract
The ability of a pathogen to survive and cause an infection is often determined by specific interactions between the host and pathogen proteins. Such interactions can be both intra- and extracellular and may define the outcome of an infection. There are a range of innovative biochemical, biophysical and bioinformatic techniques currently available to identify protein-protein interactions (PPI) between the host and the pathogen. However, the complexity and the diversity of host-pathogen PPIs has led to the development of several high throughput (HT) techniques that enable the study of multiple interactions at once and/or screen multiple samples at the same time, in an unbiased manner. We review here the major HT laboratory-based technologies employed for host-bacterial interaction studies.
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Affiliation(s)
| | - Meera Unnikrishnan
- Division of Biomedical Sciences, University of Warwick, Coventry CV4 7AL, United Kingdom.
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3
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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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4
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Meier K, Jachmann LH, Türköz G, Babu Sait MR, Pérez L, Kepp O, Valdivia RH, Kroemer G, Sixt BS. The Chlamydia effector CpoS modulates the inclusion microenvironment and restricts the interferon response by acting on Rab35. mBio 2023; 14:e0319022. [PMID: 37530528 PMCID: PMC10470785 DOI: 10.1128/mbio.03190-22] [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: 05/15/2023] [Accepted: 06/13/2023] [Indexed: 08/03/2023] Open
Abstract
The obligate intracellular bacterium Chlamydia trachomatis inserts a family of inclusion membrane (Inc) proteins into the membrane of its vacuole (the inclusion). The Inc CpoS is a critical suppressor of host cellular immune surveillance, but the underlying mechanism remained elusive. By complementing a cpoS mutant with various natural orthologs and variants of CpoS, we linked distinct molecular interactions of CpoS to distinct functions. Unexpectedly, we found CpoS to be essential for the formation of inclusion membrane microdomains that control the spatial organization of multiple Incs involved in signaling and modulation of the host cellular cytoskeleton. While the function of CpoS in microdomains was uncoupled from its role in the suppression of host cellular defenses, we found the ability of CpoS to interact with Rab GTPases to be required not only for the manipulation of membrane trafficking, such as to mediate transport of ceramide-derived lipids (sphingolipids) to the inclusion, but also for the inhibition of Stimulator of interferon genes (STING)-dependent type I interferon responses. Indeed, depletion of Rab35 phenocopied the exacerbated interferon responses observed during infection with CpoS-deficient mutants. Overall, our findings highlight the role of Inc-Inc interactions in shaping the inclusion microenvironment and the modulation of membrane trafficking as a pathogenic immune evasion strategy. IMPORTANCE Chlamydia trachomatis is a prevalent bacterial pathogen that causes blinding ocular scarring and urogenital infections that can lead to infertility and pregnancy complications. Because Chlamydia can only grow within its host cell, boosting the intrinsic defenses of human cells may represent a novel strategy to fight pathogen replication and survival. Hence, CpoS, a Chlamydia protein known to block host cellular defenses, or processes regulated by CpoS, could provide new opportunities for therapeutic intervention. By revealing CpoS as a multifunctional virulence factor and by linking its ability to block host cellular immune signaling to the modulation of membrane trafficking, the present work may provide a foundation for such rationale targeting and advances our understanding of how intracellular bacteria can shape and protect their growth niche.
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Affiliation(s)
- Karsten Meier
- Department 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
| | - Lana H. Jachmann
- Department 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
| | - Gözde Türköz
- Department 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
| | - Mohammed Rizwan Babu Sait
- Department 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
| | - Lucía Pérez
- Department 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
| | - Oliver Kepp
- Metabolomics and Cell Biology Platforms, Institut Gustave Roussy, Villejuif, France
- Centre de Recherche des Cordeliers, Equipe labellisée par la Ligue contre le cancer, Université de Paris, Sorbonne Université, Inserm U1138, Institut Universitaire de France, Paris, France
| | - Raphael H. Valdivia
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, North Carolina, USA
| | - Guido Kroemer
- Metabolomics and Cell Biology Platforms, Institut Gustave Roussy, Villejuif, France
- Centre de Recherche des Cordeliers, Equipe labellisée par la Ligue contre le cancer, Université de Paris, Sorbonne Université, Inserm U1138, Institut Universitaire de France, Paris, France
- Department of Biology, Institut du Cancer Paris CARPEM, Hôpital Européen Georges-Pompidou, AP-HP, Paris, France
| | - Barbara S. Sixt
- Department 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
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Happonen LJ. Affinity-Purification Combined with Crosslinking Mass Spectrometry for Identification and Structural Modeling of Host-Pathogen Protein-Protein Complexes. Methods Mol Biol 2023; 2674:181-200. [PMID: 37258968 DOI: 10.1007/978-1-0716-3243-7_12] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Host-pathogen protein-protein interactions are highly complex and dynamic and mediate key steps in pathogen adhesion to host, host invasion, and colonization as well as immune evasion. In bacteria, these interactions most often involve specialized virulence factors or effector proteins that specifically target central host proteins. Here, I present a mass spectrometry-based proteomics approach starting with the identification of host-pathogen interactions by affinity-purification followed by mapping the specific host-pathogen protein-protein interaction interfaces by crosslinking mass spectrometry and structural modeling of the complexes.
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Affiliation(s)
- Lotta J Happonen
- Department of Clinical Sciences Lund, Division of Infection Medicine, Lund University, Lund, Sweden.
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6
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Chlamydia trachomatis Alters Mitochondrial Protein Composition and Secretes Effector Proteins That Target Mitochondria. mSphere 2022; 7:e0042322. [PMID: 36286535 PMCID: PMC9769516 DOI: 10.1128/msphere.00423-22] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Mitochondria are critical cellular organelles that perform a wide variety of functions, including energy production and immune regulation. To perform these functions, mitochondria contain approximately 1,500 proteins, the majority of which are encoded in the nuclear genome, translated in the cytoplasm, and translocated to the mitochondria using distinct mitochondrial targeting sequences (MTS). Bacterial proteins can also contain MTS and localize to the mitochondria. For the obligate intracellular human pathogen Chlamydia trachomatis, interaction with various host cell organelles promotes intracellular replication. However, the extent and mechanisms through which Chlamydia cells interact directly with mitochondria remain unclear. We investigated the presence of MTS in the C. trachomatis genome and discovered 30 genes encoding proteins with around 70% or greater probability of mitochondrial localization. Five are translocated to the mitochondria upon ectopic expression in HeLa cells. Mass spectrometry of isolated mitochondria from infected cells revealed that two of these proteins localize to the mitochondria during infection. Comparison of mitochondria from infected and uninfected cells suggests that chlamydial infection affects the mitochondrial protein composition. Around 125 host proteins were significantly decreased or absent in mitochondria from infected cells. Among these were proapoptotic factors and those related to mitochondrial fission/fusion dynamics. Conversely, 82 host proteins were increased in or specific to mitochondria of infected cells, many of which act as antiapoptotic factors and upregulators of cellular metabolism. These data support the notion that C. trachomatis specifically targets host mitochondria to manipulate cell fate decisions and metabolic function to support pathogen survival and replication. IMPORTANCE Obligate intracellular bacteria have evolved multiple means to promote their intracellular survival and replication within the otherwise harsh environment of the eukaryotic cell. Nutrient acquisition and avoidance of cellular defense mechanisms are critical to an intracellular lifestyle. Mitochondria are critical organelles that produce energy in the form of ATP and regulate programmed cell death responses to invasive pathogenic microbes. Cell death prior to completion of replication would be detrimental to the pathogen. C. trachomatis produces at least two and possibly more proteins that target the mitochondria. Collectively, C. trachomatis infection modulates the mitochondrial protein composition, favoring a profile suggestive of downregulation of apoptosis.
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7
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Jiang C, Huang X, Yao J, Yu L, Wei F, Yang A. The role of membrane contact sites at the bacteria-host interface. Crit Rev Microbiol 2021; 48:270-282. [PMID: 34403642 DOI: 10.1080/1040841x.2021.1961678] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Membrane contact sites (MCSs) refer to the areas of close proximity between heterologous membranes. A growing body of evidence indicates that MCSs are involved in important cellular functions, such as cellular material transfer, organelle biogenesis, and cell growth. Importantly, the study of MCSs at the bacteria-host interface is an emerging popular research topic. Intracellular bacterial pathogens have evolved a variety of fascinating strategies to interfere with MCSs by injecting effectors into infected host cells. Bacteria-containing vacuoles establish direct physical contact with organelles within the host, ensuring vacuolar membrane integrity and energy supply from host organelles and protecting the vacuoles from the host endocytic pathway and lysosomal degradation. An increasing number of bacterial effectors from various bacterial pathogens hijack components of host MCSs to form the vacuole-organelle MCSs for material exchange. MCS-related events have been identified as new mechanisms of microbial pathogenesis to greatly improve bacterial survival and replication within host cells. In this review, we will discuss the recent advances in MCSs at the bacteria-host interface, focussing on the roles of MCSs mediated by bacterial effectors in microbial pathogenesis.
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Affiliation(s)
- Chen Jiang
- School of Life Sciences, Chongqing University, Chongqing, China
| | - Xue Huang
- School of Life Sciences, Chongqing University, Chongqing, China
| | - Jia Yao
- School of Life Sciences, Chongqing University, Chongqing, China
| | - Lihua Yu
- School of Life Sciences, Chongqing University, Chongqing, China
| | - Fujing Wei
- School of Life Sciences, Chongqing University, Chongqing, China
| | - Aimin Yang
- School of Life Sciences, Chongqing University, Chongqing, China
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8
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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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The Small Molecule H89 Inhibits Chlamydia Inclusion Growth and Production of Infectious Progeny. Infect Immun 2021; 89:e0072920. [PMID: 33820812 PMCID: PMC8373235 DOI: 10.1128/iai.00729-20] [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] [Indexed: 12/02/2022] Open
Abstract
Chlamydia is an obligate intracellular bacterium and the most common reportable cause of human infection in the United States. This pathogen proliferates inside a eukaryotic host cell, where it resides within a membrane-bound compartment called the chlamydial inclusion. It has an unusual developmental cycle, marked by conversion between a replicating form, the reticulate body (RB), and an infectious form, the elementary body (EB). We found that the small molecule H89 slowed inclusion growth and decreased overall RB replication by 2-fold but caused a 25-fold reduction in infectious EBs. This disproportionate effect on EB production was mainly due to a defect in RB-to-EB conversion and not to the induction of chlamydial persistence, which is an altered growth state. Although H89 is a known inhibitor of specific protein kinases and vesicular transport to and from the Golgi apparatus, it did not cause these anti-chlamydial effects by blocking protein kinase A or C or by inhibiting protein or lipid transport. Thus, H89 is a novel anti-chlamydial compound that has a unique combination of effects on an intracellular Chlamydia infection.
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Banerjee A, Nelson DE. The growing repertoire of genetic tools for dissecting chlamydial pathogenesis. Pathog Dis 2021; 79:ftab025. [PMID: 33930127 PMCID: PMC8112481 DOI: 10.1093/femspd/ftab025] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Accepted: 04/28/2021] [Indexed: 01/29/2023] Open
Abstract
Multiple species of obligate intracellular bacteria in the genus Chlamydia are important veterinary and/or human pathogens. These pathogens all share similar biphasic developmental cycles and transition between intracellular vegetative reticulate bodies and infectious elementary forms, but vary substantially in their host preferences and pathogenic potential. A lack of tools for genetic engineering of these organisms has long been an impediment to the study of their biology and pathogenesis. However, the refinement of approaches developed in C. trachomatis over the last 10 years, and adaptation of some of these approaches to other Chlamydia spp. in just the last few years, has opened exciting new possibilities for studying this ubiquitous group of important pathogens.
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Affiliation(s)
- Arkaprabha Banerjee
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - David E Nelson
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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mSphere of Influence: Where the Pathogen Proteins Are. mSphere 2021; 6:6/3/e00365-21. [PMID: 33952666 PMCID: PMC8103990 DOI: 10.1128/msphere.00365-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Aaron Reinke studies microsporidian evolution and how microsporidia interact with their hosts. In this mSphere of Influence article, he reflects on how the papers “A promiscuous biotin ligase fusion protein identifies proximal and interacting proteins in mammalian cells” (K. Aaron Reinke studies microsporidian evolution and how microsporidia interact with their hosts. In this mSphere of Influence article, he reflects on how the papers “A promiscuous biotin ligase fusion protein identifies proximal and interacting proteins in mammalian cells” (K. J. Roux, D. I. Kim, M. Raida, and B. Burke, J Cell Biol 196:801–810, 2012, https://doi.org/10.1083/jcb.201112098) and “Proteomic mapping of mitochondria in living cells via spatially restricted enzymatic tagging” (H.-W. Rhee, P. Zou, N. D. Udeshi, J. D. Martell, et al., Science 339:1328–1331, 2013, https://doi.org/10.1126/science.1230593) impacted his thinking on how to determine where proteins from intracellular pathogens are located within host cells.
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12
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Quistgaard EM. BAP31: Physiological functions and roles in disease. Biochimie 2021; 186:105-129. [PMID: 33930507 DOI: 10.1016/j.biochi.2021.04.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Revised: 04/20/2021] [Accepted: 04/21/2021] [Indexed: 12/22/2022]
Abstract
B-cell receptor-associated protein 31 (BAP31 or BCAP31) is a ubiquitously expressed transmembrane protein found mainly in the endoplasmic reticulum (ER), including in mitochondria-associated membranes (MAMs). It acts as a broad-specificity membrane protein chaperone and quality control factor, which can promote different fates for its clients, including ER retention, ER export, ER-associated degradation (ERAD), or evasion of degradation, and it also acts as a MAM tetherer and regulatory protein. It is involved in several cellular processes - it supports ER and mitochondrial homeostasis, promotes proliferation and migration, plays several roles in metabolism and the immune system, and regulates autophagy and apoptosis. Full-length BAP31 can be anti-apoptotic, but can also mediate activation of caspase-8, and itself be cleaved by caspase-8 into p20-BAP31, which promotes apoptosis by mobilizing ER calcium stores at MAMs. BAP31 loss-of-function mutations is the cause of 'deafness, dystonia, and central hypomyelination' (DDCH) syndrome, characterized by severe neurological symptoms and early death. BAP31 is furthermore implicated in a growing number of cancers and other diseases, and several viruses have been found to target it to promote their survival or life cycle progression. The purpose of this review is to provide an overview and examination of the basic properties, functions, mechanisms, and roles in disease of BAP31.
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Affiliation(s)
- Esben M Quistgaard
- Department of Molecular Biology and Genetics - DANDRITE, Aarhus University, Gustav Wieds Vej 10, DK-8000 Aarhus C, Denmark.
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13
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Zapatero-Belinchón FJ, Carriquí-Madroñal B, Gerold G. Proximity labeling approaches to study protein complexes during virus infection. Adv Virus Res 2021; 109:63-104. [PMID: 33934830 DOI: 10.1016/bs.aivir.2021.02.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Cellular compartmentalization of proteins and protein complex formation allow cells to tightly control biological processes. Therefore, understanding the subcellular localization and interactions of a specific protein is crucial to uncover its biological function. The advent of proximity labeling (PL) has reshaped cellular proteomics in infection biology. PL utilizes a genetically modified enzyme that generates a "labeling cloud" by covalently labeling proteins in close proximity to the enzyme. Fusion of a PL enzyme to a specific antibody or a "bait" protein of interest in combination with affinity enrichment mass spectrometry (AE-MS) enables the isolation and identification of the cellular proximity proteome, or proxisome. This powerful methodology has been paramount for the mapping of membrane or membraneless organelles as well as for the understanding of hard-to-purify protein complexes, such as those of transmembrane proteins. Unsurprisingly, more and more infection biology research groups have recognized the potential of PL for the identification of host-pathogen interactions. In this chapter, we introduce the enzymes commonly used for PL labeling as well as recent promising advancements and summarize the major achievements in organelle mapping and nucleic acid PL. Moreover, we comprehensively describe the research on host-pathogen interactions using PL, giving special attention to studies in the field of virology.
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Affiliation(s)
- Francisco José Zapatero-Belinchón
- Department of Biochemistry & Research Center for Emerging Infections and Zoonoses (RIZ), University of Veterinary Medicine Hannover, Hannover, Germany; Institute for Experimental Virology, TWINCORE, Centre for Experimental and Clinical Infection Research, a Joint Venture Between the Medical School Hannover and the Helmholtz Centre for Infection Research, Hannover, Germany; Department of Clinical Microbiology, Virology, Umeå University, Umeå, Sweden; Wallenberg Centre for Molecular Medicine (WCMM), Umeå University, Umeå, Sweden.
| | - Belén Carriquí-Madroñal
- Department of Biochemistry & Research Center for Emerging Infections and Zoonoses (RIZ), University of Veterinary Medicine Hannover, Hannover, Germany; Institute for Experimental Virology, TWINCORE, Centre for Experimental and Clinical Infection Research, a Joint Venture Between the Medical School Hannover and the Helmholtz Centre for Infection Research, Hannover, Germany
| | - Gisa Gerold
- Department of Biochemistry & Research Center for Emerging Infections and Zoonoses (RIZ), University of Veterinary Medicine Hannover, Hannover, Germany; Institute for Experimental Virology, TWINCORE, Centre for Experimental and Clinical Infection Research, a Joint Venture Between the Medical School Hannover and the Helmholtz Centre for Infection Research, Hannover, Germany; Department of Clinical Microbiology, Virology, Umeå University, Umeå, Sweden; Wallenberg Centre for Molecular Medicine (WCMM), Umeå University, Umeå, Sweden.
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14
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Effectors Targeting the Unfolded Protein Response during Intracellular Bacterial Infection. Microorganisms 2021; 9:microorganisms9040705. [PMID: 33805575 PMCID: PMC8065698 DOI: 10.3390/microorganisms9040705] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2021] [Revised: 03/21/2021] [Accepted: 03/24/2021] [Indexed: 12/12/2022] Open
Abstract
The unfolded protein response (UPR) is a homeostatic response to endoplasmic reticulum (ER) stress within eukaryotic cells. The UPR initiates transcriptional and post-transcriptional programs to resolve ER stress; or, if ER stress is severe or prolonged, initiates apoptosis. ER stress is a common feature of bacterial infection although the role of the UPR in host defense is only beginning to be understood. While the UPR is important for host defense against pore-forming toxins produced by some bacteria, other bacterial effector proteins hijack the UPR through the activity of translocated effector proteins that facilitate intracellular survival and proliferation. UPR-mediated apoptosis can limit bacterial replication but also often contributes to tissue damage and disease. Here, we discuss the dual nature of the UPR during infection and the implications of UPR activation or inhibition for inflammation and immunity as illustrated by different bacterial pathogens.
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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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Chlamydia trachomatis TmeA Directly Activates N-WASP To Promote Actin Polymerization and Functions Synergistically with TarP during Invasion. mBio 2021; 12:mBio.02861-20. [PMID: 33468693 PMCID: PMC7845632 DOI: 10.1128/mbio.02861-20] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The increasing genetic tractability of Chlamydia trachomatis is accelerating the ability to characterize the unique infection biology of this obligate intracellular parasite. These efforts are leading to a greater understanding of the molecular events associated with key virulence requirements. Chlamydia trachomatis is a medically significant human pathogen and is an epithelial-tropic obligate intracellular parasite. Invasion of nonprofessional phagocytes represents a crucial step in the infection process and has likely promoted the evolution of a redundant mechanism and routes of entry. Like many other viral and invasive bacterial pathogens, manipulation of the host cell cytoskeleton represents a focal point in Chlamydia entry. The advent of genetic techniques in C. trachomatis, such as creation of complete gene deletions via fluorescence-reported allelic exchange mutagenesis (FRAEM), is providing important tools to unravel the contributions of bacterial factors in these complex pathways. The type III secretion chaperone Slc1 directs delivery of at least four effectors during the invasion process. Two of these, TarP and TmeA, have been associated with manipulation of actin networks and are essential for normal levels of invasion. The functions of TarP are well established, whereas TmeA is less well characterized. We leverage chlamydial genetics and proximity labeling here to provide evidence that TmeA directly targets host N-WASP to promote Arp2/3-dependent actin polymerization. Our work also shows that TmeA and TarP influence separate, yet synergistic pathways to accomplish chlamydial entry. These data further support an appreciation that a pathogen, confined by a reductionist genome, retains the ability to commit considerable resources to accomplish bottle-neck steps during the infection process.
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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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Sukumaran A, Woroszchuk E, Ross T, Geddes-McAlister J. Proteomics of host-bacterial interactions: new insights from dual perspectives. Can J Microbiol 2020; 67:213-225. [PMID: 33027598 DOI: 10.1139/cjm-2020-0324] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Mass-spectrometry (MS)-based proteomics is a powerful and robust platform for studying the interactions between biological systems during health and disease. Bacterial infections represent a significant threat to global health and drive the pursuit of novel therapeutic strategies to combat emerging and resistant pathogens. During infection, the interplay between a host and pathogen determines the ability of the microbe to survive in a hostile environment and promotes an immune response by the host as a protective measure. It is the protein-level changes from either biological system that define the outcome of infection, and MS-based proteomics provides a rapid and effective platform to identify such changes. In particular, proteomics detects alterations in protein abundance, quantifies protein secretion and (or) release, measures an array of post-translational modifications that influence signaling cascades, and profiles protein-protein interactions through protein complex and (or) network formation. Such information provides new insight into the role of known and novel bacterial effectors, as well as the outcome of host cell activation. In this Review, we highlight the diverse applications of MS-based proteomics in profiling the relationship between bacterial pathogens and the host. Our work identifies a plethora of strategies for exploring mechanisms of infection from dual perspectives (i.e., host and pathogen), and we suggest opportunities to extrapolate the current knowledgebase to other biological systems for applications in therapeutic discovery.
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Affiliation(s)
- Arjun Sukumaran
- Molecular and Cellular Biology Department, University of Guelph, Guelph, ON N1G 2W1, Canada.,Molecular and Cellular Biology Department, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Elizabeth Woroszchuk
- Molecular and Cellular Biology Department, University of Guelph, Guelph, ON N1G 2W1, Canada.,Molecular and Cellular Biology Department, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Taylor Ross
- Molecular and Cellular Biology Department, University of Guelph, Guelph, ON N1G 2W1, Canada.,Molecular and Cellular Biology Department, University of Guelph, Guelph, ON N1G 2W1, Canada
| | - Jennifer Geddes-McAlister
- Molecular and Cellular Biology Department, University of Guelph, Guelph, ON N1G 2W1, Canada.,Molecular and Cellular Biology Department, University of Guelph, Guelph, ON N1G 2W1, Canada
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Contributions of Mass Spectrometry-Based Proteomics to Understanding Salmonella-Host Interactions. Pathogens 2020; 9:pathogens9070581. [PMID: 32708900 PMCID: PMC7400052 DOI: 10.3390/pathogens9070581] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 07/13/2020] [Accepted: 07/16/2020] [Indexed: 02/02/2023] Open
Abstract
As a model pathogen, Salmonella invades both phagocytic and non-phagocytic host cells and adopts an intracellular lifestyle in a membrane-bound compartment during infection. Therefore, a systemic overview of Salmonella adaptations to distinct host cells together with host remodeling will assist us in charting the landscape of host-pathogen interactions. Central to the Salmonella-host interplay are bacterial virulence factors (effectors) that are injected into host cells by type III secretion systems (T3SSs). Despite great progress, functional studies of bacterial effectors have experienced daunting challenges as well. In the last decade, mass spectrometry-based proteomics has evolved into a powerful technological platform that can quantitatively measure thousands of proteins in terms of their expression as well as post-translational modifications. Here, we will review the applications of high-throughput proteomic technologies in understanding the dynamic reprogramming of both Salmonella and host proteomes during the course of infection. Furthermore, we will summarize the progress in utilizing affinity purification-mass spectrometry to screen for host substrates of Salmonella T3SS effectors. Finally, we will critically discuss some limitations/challenges with current proteomic platforms in the context of host-pathogen interactions and highlight some emerging technologies that may offer the promise of tackling these problems.
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20
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Kebbi-Beghdadi C, Pilloux L, Martin V, Greub G. Eukaryotic Cell Permeabilisation to Identify New Putative Chlamydial Type III Secretion System Effectors Secreted within Host Cell Cytoplasm. Microorganisms 2020; 8:microorganisms8030361. [PMID: 32138376 PMCID: PMC7143554 DOI: 10.3390/microorganisms8030361] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 02/27/2020] [Accepted: 02/28/2020] [Indexed: 02/08/2023] Open
Abstract
Chlamydia trachomatis and Waddlia chondrophila are strict intracellular bacteria belonging to the Chlamydiales order. C. trachomatis is the most frequent bacterial cause of genital and ocular infections whereas W. chondrophila is an opportunistic pathogen associated with adverse pregnancy outcomes and respiratory infections. Being strictly intracellular, these bacteria are engaged in a complex interplay with their hosts to modulate their environment and create optimal conditions for completing their life cycle. For this purpose, they possess several secretion pathways and, in particular, a Type III Secretion System (T3SS) devoted to the delivery of effector proteins in the host cell cytosol. Identifying these effectors is a crucial step in understanding the molecular basis of bacterial pathogenesis. Following incubation of infected cells with perfringolysin O, a pore-forming toxin that binds cholesterol present in plasma membranes, we analysed by mass spectrometry the protein content of the host cell cytoplasm. We identified 13 putative effectors secreted by C. trachomatis and 19 secreted by W. chondrophila. Using Y. enterocolitica as a heterologous expression and secretion system, we confirmed that four of these identified proteins are secreted by the T3SS. Two W. chondrophila T3SS effectors (hypothetical proteins Wcw_0499 and Wcw_1706) were further characterised and demonstrated to be early/mid-cycle effectors. In addition, Wcw_1706 is associated with a tetratricopeptide domain-containing protein homologous to C. trachomatis class II chaperone. Furthermore, we identified a novel C. trachomatis effector, CT460 that localises in the eukaryotic nucleus when ectopically expressed in 293 T cells.
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Affiliation(s)
| | | | | | - Gilbert Greub
- Correspondence: ; Tel.: +41-21-314-4979; Fax: +41-21-314-4060
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21
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Olson MG, Ouellette SP, Rucks EA. A meta-analysis of affinity purification-mass spectrometry experimental systems used to identify eukaryotic and chlamydial proteins at the Chlamydia trachomatis inclusion membrane. J Proteomics 2019; 212:103595. [PMID: 31760040 DOI: 10.1016/j.jprot.2019.103595] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 11/13/2019] [Accepted: 11/19/2019] [Indexed: 12/12/2022]
Abstract
The obligate intracellular bacterial pathogen, Chlamydia trachomatis, develops within a membrane-bound vacuole termed the inclusion. Affinity purification-mass spectrometry (AP-MS) experiments to study the interactions that occur at the chlamydial inclusion membrane have been performed and, more recently, combined with advances in C. trachomatis genetics. However, each of the four AP-MS published reports used either different experimental approaches or statistical tools to identify proteins that localize at the inclusion. We critically analyzed each experimental approach and performed a meta-analysis of the reported statistically significant proteins for each study, finding that only a few eukaryotic proteins were commonly identified between all four experimental approaches. The two similarly conducted in vivo labeling studies were compared using the same statistical analysis tool, Significance Analysis of INTeractome (SAINT), which revealed a disparity in the number of significant proteins identified by the original analysis. We further examined methods to identify potential background contaminant proteins that remain after statistical analysis. Overall, this meta-analysis highlights the importance of carefully controlling and analyzing the AP-MS data so that pertinent information can be obtained from these various AP-MS experimental approaches. This study provides important guidelines and considerations for using this methodology to study intracellular pathogens residing within a membrane-bound compartment. SIGNIFICANCE: Chlamydia trachomatis, an obligate intracellular pathogen, grows within a membrane-bound vacuole termed the inclusion. The inclusion is studded with bacterial membrane proteins that likely orchestrate numerous interactions with the host cell. Although maintenance of the intracellular niche is vital, an understanding of the host-pathogen interactions that occur at the inclusion membrane is limited by the difficulty in purifying membrane protein fractions from infected host cells. The experimental procedures necessary to solubilize hydrophobic proteins fail to maintain transient protein-protein interactions. Advances in C. trachomatis genetics has allowed us and others to use various experimental approaches in combination with affinity purification mass spectrometry (AP-MS) to study the interactions that occur at the chlamydial vacuolar, or inclusion, membrane. For the first time, two groups have published AP-MS studies using the same tool, the ascorbate peroxidase proximity labeling system (APEX2), which overcomes past experimental limitations because membrane protein interactions are labeled in vivo in the context of infection. The utility of this system is highlighted by its ability to study chlamydial type III secreted inclusion membrane protein (Inc) interactions. Incs act as the mediators of host-pathogen interactions at the inclusion during C. trachomatis infection. When carefully controlled and analyzed, the data obtained can yield copious amounts of useful information. Here, we critically analyzed four previously published studies, including statistical analysis of AP-MS datasets related to Chlamydia-host interactions, to contextualize the data and to identify the best practices in interpreting these types of complex outputs.
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Affiliation(s)
- Macy G Olson
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE, USA
| | - Scot P Ouellette
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE, USA.
| | - Elizabeth A Rucks
- Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE, USA.
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Santin YG. Uncovering the In Vivo Proxisome Using Proximity‐Tagging Methods. Bioessays 2019; 41:e1900131. [DOI: 10.1002/bies.201900131] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Revised: 10/04/2019] [Indexed: 12/28/2022]
Affiliation(s)
- Yoann G. Santin
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, Institut de Microbiologie de la MéditerranéeAix‐Marseille Université – CNRS UMR7255 31 Chemin Joseph Aiguier, CS70071, 13402 Marseille Cedex 09 France
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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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Dolat L, Valdivia RH. A renewed tool kit to explore Chlamydia pathogenesis: from molecular genetics to new infection models. F1000Res 2019; 8. [PMID: 31249676 PMCID: PMC6589931 DOI: 10.12688/f1000research.18832.1] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 06/12/2019] [Indexed: 12/21/2022] Open
Abstract
Chlamydia trachomatis is the most prevalent sexually transmitted bacterial pathogen and the leading cause of preventable blindness in the developing world.
C. trachomatis invades the epithelium of the conjunctiva and genital tract and replicates within an intracellular membrane-bound compartment termed the inclusion. To invade and replicate in mammalian cells,
Chlamydia remodels epithelial surfaces by reorganizing the cytoskeleton and cell–cell adhesions, reprograms membrane trafficking, and modulates cell signaling to dampen innate immune responses. If the infection ascends to the upper female genital tract, it can result in pelvic inflammatory disease and tissue scarring.
C. trachomatis infections are associated with infertility, ectopic pregnancies, the fibrotic disorder endometriosis, and potentially cancers of the cervix and uterus. Unfortunately, the molecular mechanisms by which this clinically important human pathogen subverts host cellular functions and causes disease have remained relatively poorly understood because of the dearth of molecular genetic tools to study
Chlamydiae and limitations of both
in vivo and
in vitro infection models. In this review, we discuss recent advances in the experimental molecular tool kit available to dissect
C. trachomatis infections with a special focus on
Chlamydia-induced epithelial barrier disruption by regulating the structure, function, and dynamics of epithelial cell–cell junctions.
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Affiliation(s)
- Lee Dolat
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, USA
| | - Raphael H Valdivia
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, USA
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