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Steiert B, Andersen SE, McCaslin PN, Elwell CA, Faris R, Tijerina X, Smith P, Eldridge Q, Imai BS, Arrington JV, Yau PM, Mirrashidi KM, Johnson JR, Verschueren E, Von Dollen J, Jang GM, Krogan NJ, Engel JN, Weber MM. Global mapping of the Chlamydia trachomatis conventional secreted effector - host interactome reveals CebN interacts with nucleoporins and Rae1 to impede STAT1 nuclear translocation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.25.587017. [PMID: 38712050 PMCID: PMC11071493 DOI: 10.1101/2024.04.25.587017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2024]
Abstract
Chlamydia trachomatis (C.t.), the leading cause of bacterial sexually transmitted infections, employs a type III secretion system (T3SS) to translocate two classes of effectors, inclusion membrane proteins and conventional T3SS (cT3SS) effectors, into the host cell to counter host defense mechanisms. Here we employed three assays to directly evaluate secretion during infection, validating secretion for 23 cT3SS effectors. As bioinformatic analyses have been largely unrevealing, we conducted affinity purification-mass spectrometry to identify host targets and gain insights into the functions of these effectors, identifying high confidence interacting partners for 21 cT3SS effectors. We demonstrate that CebN localizes to the nuclear envelope in infected and bystander cells where it interacts with multiple nucleoporins and Rae1, blocking STAT1 nuclear import following IFN-γ stimulation. By building a cT3SS effector-host interactome, we have identified novel pathways that are targeted during bacterial infection and have begun to address how C.t. effectors combat cell autonomous immunity.
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Affiliation(s)
- Brianna Steiert
- Department of Microbiology and Immunology, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| | - Shelby E. Andersen
- Department of Microbiology and Immunology, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
- Present address: Department of Immunology and Microbiology, University of Colorado - Anschutz Medical Campus, Aurora, CO, USA
| | - Paige N. McCaslin
- Department of Microbiology and Immunology, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| | - Cherilyn A. Elwell
- Department of Medicine, University of California, San Francisco, San Francisco, CA, USA
| | - Robert Faris
- Department of Microbiology and Immunology, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| | - Xavier Tijerina
- Department of Microbiology and Immunology, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| | - Parker Smith
- Department of Microbiology and Immunology, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| | - Quinn Eldridge
- Department of Microbiology and Immunology, University of Iowa Carver College of Medicine, Iowa City, Iowa, USA
| | - Brian S. Imai
- Protein Sciences Facility, Roy J. Carver Biotechnology Center, University of Illinois Urbana–Champaign, Urbana, IL, USA
| | - Justine V. Arrington
- Protein Sciences Facility, Roy J. Carver Biotechnology Center, University of Illinois Urbana–Champaign, Urbana, IL, USA
| | - Peter M. Yau
- Protein Sciences Facility, Roy J. Carver Biotechnology Center, University of Illinois Urbana–Champaign, Urbana, IL, USA
| | | | - Jeffrey R. Johnson
- QB3, California Institute for Quantitative Biosciences, San Francisco, CA 94148, USA
| | - Erik Verschueren
- QB3, California Institute for Quantitative Biosciences, San Francisco, CA 94148, USA
| | - John Von Dollen
- QB3, California Institute for Quantitative Biosciences, San Francisco, CA 94148, USA
| | - Gwendolyn M. Jang
- QB3, California Institute for Quantitative Biosciences, San Francisco, CA 94148, 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 N. Engel
- Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA, USA
| | - Mary M. Weber
- Department of Microbiology and Immunology, University of Iowa Carver College of Medicine, Iowa City, Iowa, 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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Chen K, Healy MD, Collins BM. Towards a molecular understanding of endosomal trafficking by Retromer and Retriever. Traffic 2019; 20:465-478. [DOI: 10.1111/tra.12649] [Citation(s) in RCA: 92] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2019] [Revised: 04/15/2019] [Accepted: 04/15/2019] [Indexed: 12/16/2022]
Affiliation(s)
- Kai‐En Chen
- Institute for Molecular Bioscience University of Queensland St. Lucia Queensland Australia
| | - Michael D. Healy
- Institute for Molecular Bioscience University of Queensland St. Lucia Queensland Australia
| | - Brett M. Collins
- Institute for Molecular Bioscience University of Queensland St. Lucia Queensland Australia
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Characterization of the Mode of Action of Aurodox, a Type III Secretion System Inhibitor from Streptomyces goldiniensis. Infect Immun 2019; 87:IAI.00595-18. [PMID: 30455200 PMCID: PMC6346137 DOI: 10.1128/iai.00595-18] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2018] [Accepted: 11/12/2018] [Indexed: 11/20/2022] Open
Abstract
Recent work has demonstrated that the polyketide natural product Aurodox from Streptomyces goldiniensis is able to block the pathogenesis of the murine pathogen Citrobacter rodentium. In this work, we aimed to gain a better understanding of the mechanism of action of the compound. Recent work has demonstrated that the polyketide natural product Aurodox from Streptomyces goldiniensis is able to block the pathogenesis of the murine pathogen Citrobacter rodentium. In this work, we aimed to gain a better understanding of the mechanism of action of the compound. We show that Aurodox downregulates the expression of the type III secretion systems of enteropathogenic and enterohemorrhagic Escherichia coli. Furthermore, we have used transcriptomic analysis to show that Aurodox inhibits the expression at the transcriptional level by repressing the master regulator, ler. Our data support a model in which Aurodox acts upstream of ler and not directly on the secretion system itself. Finally, we have shown that Aurodox, unlike some traditional antibiotics, does not induce expression of RecA, which is essential for the production of Shiga toxin. We propose that these properties nominate Aurodox as a promising antivirulence therapy for the treatment of these infections.
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Healy MD, Hospenthal MK, Hall RJ, Chandra M, Chilton M, Tillu V, Chen KE, Celligoi DJ, McDonald FJ, Cullen PJ, Lott JS, Collins BM, Ghai R. Structural insights into the architecture and membrane interactions of the conserved COMMD proteins. eLife 2018; 7:e35898. [PMID: 30067224 PMCID: PMC6089597 DOI: 10.7554/elife.35898] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2018] [Accepted: 07/31/2018] [Indexed: 12/31/2022] Open
Abstract
The COMMD proteins are a conserved family of proteins with central roles in intracellular membrane trafficking and transcription. They form oligomeric complexes with each other and act as components of a larger assembly called the CCC complex, which is localized to endosomal compartments and mediates the transport of several transmembrane cargos. How these complexes are formed however is completely unknown. Here, we have systematically characterised the interactions between human COMMD proteins, and determined structures of COMMD proteins using X-ray crystallography and X-ray scattering to provide insights into the underlying mechanisms of homo- and heteromeric assembly. All COMMD proteins possess an α-helical N-terminal domain, and a highly conserved C-terminal domain that forms a tightly interlocked dimeric structure responsible for COMMD-COMMD interactions. The COMM domains also bind directly to components of CCC and mediate non-specific membrane association. Overall these studies show that COMMD proteins function as obligatory dimers with conserved domain architectures.
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Affiliation(s)
- Michael D Healy
- Institute for Molecular BioscienceThe University of QueenslandSt. LuciaAustralia
| | | | - Ryan J Hall
- Institute for Molecular BioscienceThe University of QueenslandSt. LuciaAustralia
| | - Mintu Chandra
- Institute for Molecular BioscienceThe University of QueenslandSt. LuciaAustralia
| | - Molly Chilton
- School of Biochemistry, Biomedical Sciences BuildingUniversity of BristolBristolUnited Kingdom
| | - Vikas Tillu
- Institute for Molecular BioscienceThe University of QueenslandSt. LuciaAustralia
| | - Kai-En Chen
- Institute for Molecular BioscienceThe University of QueenslandSt. LuciaAustralia
| | - Dion J Celligoi
- School of Biological SciencesThe University of AucklandAucklandNew Zealand
| | | | - Peter J Cullen
- School of Biochemistry, Biomedical Sciences BuildingUniversity of BristolBristolUnited Kingdom
| | - J Shaun Lott
- School of Biological SciencesThe University of AucklandAucklandNew Zealand
| | - Brett M Collins
- Institute for Molecular BioscienceThe University of QueenslandSt. LuciaAustralia
| | - Rajesh Ghai
- Institute for Molecular BioscienceThe University of QueenslandSt. LuciaAustralia
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Ferrell JC, Fields KA. A working model for the type III secretion mechanism in Chlamydia. Microbes Infect 2015; 18:84-92. [PMID: 26515030 DOI: 10.1016/j.micinf.2015.10.006] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Revised: 10/19/2015] [Accepted: 10/19/2015] [Indexed: 01/09/2023]
Abstract
It has been appreciated for almost 20 years that members of the Chlamydiales possess a virulence-associated type III secretion mechanism. Given the obligate intracellular nature of these bacteria, defining exactly how type III secretion functions to promote pathogenesis has been challenging. We present a working model herein that is based on current evidence.
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Affiliation(s)
- Joshua C Ferrell
- Department of Microbiology, Immunology & Molecular Genetics, University of Kentucky College of Medicine, Lexington, KY 40536, USA
| | - Kenneth A Fields
- Department of Microbiology, Immunology & Molecular Genetics, University of Kentucky College of Medicine, Lexington, KY 40536, USA.
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Bavoil PM, Byrne GI. Analysis of CPAF mutants: new functions, new questions (the ins and outs of a chlamydial protease). Pathog Dis 2015; 71:287-91. [PMID: 24942261 DOI: 10.1111/2049-632x.12194] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Accepted: 06/06/2014] [Indexed: 12/18/2022] Open
Abstract
The role of the chlamydial protease CPAF, previously described as a secreted serine protease processing a wealth of host and chlamydial proteins to promote chlamydial intracellular growth, has recently been questioned by studies from the groups of Tan and Sütterlin, who demonstrated that the reported proteolysis of almost a dozen substrates by CPAF occurred during preparation of cell lysates rather than in intact cells. Valdivia et al. have now compared near-isogenic pairs of CPAF-deficient and secretion-deficient mutants of Chlamydia trachomatis and their wild-type parent. Their report, published in this issue of Pathogens and Disease, is a landmark study in the emerging era of Chlamydia genetics. The results of Tan and Sütterlin are confirmed with a few additions. While CPAF's role in pathogenesis is diminished considerably from these studies, CPAF remains an important factor in chlamydial biology as (1) CPAF mutants produce less infectious yield than wild type; and (2) CPAF is responsible for proteolytic cleavage of vimentin and LAP-1, but only after lysis of the inclusion membrane, not upon CPAF secretion to the cytosol. Here, we briefly review the evidence in support of CPAF's active secretion from the mid-to-late inclusion and conclude that new experimentation to establish whether or not CPAF is actively secreted should precede any new investigation of CPAF's cellular activities during mid-to-late development.
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Affiliation(s)
- Patrik M Bavoil
- Department of Microbial Pathogenesis, University of Maryland School of Dentistry, Baltimore, MD, USA
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Bulir DC, Waltho DA, Stone CB, Mwawasi KA, Nelson JC, Mahony JB. Chlamydia pneumoniae CopD translocator protein plays a critical role in type III secretion (T3S) and infection. PLoS One 2014; 9:e99315. [PMID: 24959658 PMCID: PMC4068993 DOI: 10.1371/journal.pone.0099315] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Accepted: 05/13/2014] [Indexed: 01/04/2023] Open
Abstract
Pathogenic Gram-negative bacteria use type III secretion (T3S) to inject effector proteins into the host cell to create appropriate conditions for infection and intracellular replication. Chlamydia spp. are believed to use T3S to infect their host cell, and the translocator proteins are an essential component of this system. Chlamydia pneumoniae contains genes encoding two sets of translocator proteins; CopB and CopD, and CopB2 and CopD2. In this study, we identified novel interactions between CopD and three type III secretion proteins; namely, CopN, CdsN, and CdsF. We identified a CopD putative chaperone binding motif, PxLxxP, within the N-terminal region (CopD amino acids 120-125), which was necessary for interaction with its putative chaperone LcrH_1. Using size exclusion chromatography, we showed that CopD and LcrH_1 formed higher order structures in solution with CopD and LcrH_1 binding in a ratio of 1∶1, which is unique for T3SS translocator proteins. Lastly, we showed that antibodies to CopD reduced C. pneumoniae infectivity by >95%. Collectively, this data suggests that CopD plays a critical role in pathogenesis and likely functions as a hydrophobic translocator of the type III secretion system in Chlamydia pneumoniae.
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Affiliation(s)
- David C. Bulir
- M. G. DeGroote Institute for Infectious Disease Research, Faculty of Health Sciences and Department of Pathology and Molecular Medicine, McMaster University, and Father Sean O'Sullivan Research Centre, St. Joseph's Healthcare, Hamilton, Ontario, Canada
| | - Daniel A. Waltho
- M. G. DeGroote Institute for Infectious Disease Research, Faculty of Health Sciences and Department of Pathology and Molecular Medicine, McMaster University, and Father Sean O'Sullivan Research Centre, St. Joseph's Healthcare, Hamilton, Ontario, Canada
| | - Christopher B. Stone
- M. G. DeGroote Institute for Infectious Disease Research, Faculty of Health Sciences and Department of Pathology and Molecular Medicine, McMaster University, and Father Sean O'Sullivan Research Centre, St. Joseph's Healthcare, Hamilton, Ontario, Canada
| | - Kenneth A. Mwawasi
- M. G. DeGroote Institute for Infectious Disease Research, Faculty of Health Sciences and Department of Pathology and Molecular Medicine, McMaster University, and Father Sean O'Sullivan Research Centre, St. Joseph's Healthcare, Hamilton, Ontario, Canada
| | - Jordan C. Nelson
- M. G. DeGroote Institute for Infectious Disease Research, Faculty of Health Sciences and Department of Pathology and Molecular Medicine, McMaster University, and Father Sean O'Sullivan Research Centre, St. Joseph's Healthcare, Hamilton, Ontario, Canada
| | - James B. Mahony
- M. G. DeGroote Institute for Infectious Disease Research, Faculty of Health Sciences and Department of Pathology and Molecular Medicine, McMaster University, and Father Sean O'Sullivan Research Centre, St. Joseph's Healthcare, Hamilton, Ontario, Canada
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Hanski L, Vuorela PM. Recent advances in technologies for developing drugs againstChlamydia pneumoniae. Expert Opin Drug Discov 2014; 9:791-802. [DOI: 10.1517/17460441.2014.915309] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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Pilhofer M, Aistleitner K, Ladinsky MS, König L, Horn M, Jensen GJ. Architecture and host interface of environmental chlamydiae revealed by electron cryotomography. Environ Microbiol 2013; 16:417-29. [PMID: 24118768 PMCID: PMC4949044 DOI: 10.1111/1462-2920.12299] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2013] [Accepted: 09/26/2013] [Indexed: 01/14/2023]
Abstract
Chlamydiae comprise important pathogenic and symbiotic bacteria that alternate between morphologically and physiologically different life stages during their developmental cycle. Using electron cryotomography, we characterize the ultrastructure of the developmental stages of three environmental chlamydiae: Parachlamydia acanthamoebae, Protochlamydia amoebophila and Simkania negevensis. We show that chemical fixation and dehydration alter the cell shape of Parachlamydia and that the crescent body is not a developmental stage, but an artefact of conventional electron microscopy. We further reveal type III secretion systems of environmental chlamydiae at macromolecular resolution and find support for a chlamydial needle-tip protein. Imaging bacteria inside their host cells by cryotomography for the first time, we observe marked differences in inclusion morphology and development as well as host organelle recruitment between the three chlamydial organisms, with Simkania inclusions being tightly enveloped by the host endoplasmic reticulum. The study demonstrates the power of electron cryotomography to reveal structural details of bacteria-host interactions that are not accessible using traditional methods.
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Affiliation(s)
- Martin Pilhofer
- Division of Biology, California Institute of Technology, Pasadena, CA, 91125, USA; Howard Hughes Medical Institute, Pasadena, CA, 91125, USA
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Barta ML, Hickey J, Kemege KE, Lovell S, Battaile KP, Hefty PS. Structure of CT584 from Chlamydia trachomatis refined to 3.05 Å resolution. Acta Crystallogr Sect F Struct Biol Cryst Commun 2013; 69:1196-201. [PMID: 24192348 PMCID: PMC3818032 DOI: 10.1107/s1744309113027371] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2013] [Accepted: 10/05/2013] [Indexed: 11/10/2022]
Abstract
Chlamydia trachomatis is a major cause of various diseases, including blinding trachoma and pelvic inflammatory disease, and is the leading reported sexually transmitted bacterial infection worldwide. All pathogenic Chlamydiae spp. utilize a supramolecular syringe, or type III secretion system (T3SS), to inject proteins into their obligate host in order to propagate infection. Here, the structure of CT584, a T3SS-associated protein, that has been refined to a resolution of 3.05 Å is reported. The CT584 structure is a hexamer comprised of a trimer of dimers. The structure shares a high degree of similarity to the recently reported structure of an orthologous protein, Cpn0803, from Chlamydia pneumoniae, which highlights the highly conserved nature of this protein across these chlamydial species, despite different tissue tropism and disease pathology.
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Affiliation(s)
- Michael L. Barta
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS 66045, USA
| | - John Hickey
- Department of Pharmaceutical Chemistry, University of Kansas, Lawrence, KS 66045, USA
| | - Kyle E. Kemege
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS 66045, USA
| | - Scott Lovell
- Protein Structure Laboratory, Del Shankel Structural Biology Center, University of Kansas, KS 66047, USA
| | - Kevin P. Battaile
- IMCA-CAT, Hauptman–Woodward Medical Research Institute, Argonne, IL 60439, USA
| | - P. Scott Hefty
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS 66045, USA
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Abstract
Members of the order Chlamydiales comprise a group of exquisitely evolved parasites of eukaryotic hosts that extends from single-celled amoeba to mammals. The most notable are human pathogens and include the agent of oculogenital disease Chlamydia trachomatis, the respiratory pathogen C. pneumoniae, and the zoonotic agent C. psittaci. All of these species are obligate intracellular bacteria that develop within parasitophorous vesicles termed inclusions. This demanding lifestyle necessitates orchestrated entry into nonphagocytic cells, creation of a privileged intracellular niche, and subversion of potent host defenses. All chlamydial genomes contain the coding capacity for a nonflagellar type III secretion system, and this mechanism has arisen as an essential contributor to chlamydial virulence. The emergence of tractable approaches to the genetic manipulation of chlamydiae raises the possibility of explosive progress in understanding this important contributor to chlamydial pathogenesis. This minireview considers challenges and recent advances that have revealed how chlamydiae have maintained conserved aspects of T3S while exploiting diversification to yield a system that exerts a fundamental role in the unique biology of Chlamydia species.
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Identification of novel type III secretion chaperone-substrate complexes of Chlamydia trachomatis. PLoS One 2013; 8:e56292. [PMID: 23431368 PMCID: PMC3576375 DOI: 10.1371/journal.pone.0056292] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Accepted: 01/07/2013] [Indexed: 12/17/2022] Open
Abstract
Chlamydia trachomatis is an obligate intracellular bacterial pathogen of humans that uses a type III secretion (T3S) system to manipulate host cells through the delivery of effector proteins into their cytosol and membranes. The function of T3S systems depends on small bacterial cytosolic chaperone-like proteins, which bind T3S substrates and ensure their appropriate secretion. To find novel T3S chaperone-substrate complexes of C. trachomatis we first searched its genome for genes encoding proteins with features of T3S chaperones. We then systematically tested for interactions between candidate chaperones and chlamydial T3S substrates by bacterial two-hybrid. This revealed interactions between Slc1 (a known T3S chaperone) or CT584 and several T3S substrates. Co-immunoprecipation after protein expression in Yersinia enterocolitica and protein overlay binding assays indicated that Slc1 interacted with the N-terminal region of the known T3S substrates Tarp (a previously described substrate of Slc1), CT694, and CT695, and that CT584 interacted with a central region of CT082, which we identified as a C. trachomatis T3S substrate using Y. enterocolitica as a heterologous system. Further T3S assays in Yersinia indicated that Slc1 or CT584 increased the amount of secreted Tarp, CT694, and CT695, or CT082, respectively. Expression of CT584 increased the intra-bacterial stability of CT082, while Slc1 did not affect the stability of its substrates. Overall, this indicated that in C. trachomatis Slc1 is a chaperone of multiple T3S substrates and that CT584 is a chaperone of the newly identified T3S substrate CT082.
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