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Chiarelli TJ, Grieshaber NA, Appa C, Grieshaber SS. Computational Modeling of the Chlamydial Developmental Cycle Reveals a Potential Role for Asymmetric Division. mSystems 2023; 8:e0005323. [PMID: 36927072 PMCID: PMC10134819 DOI: 10.1128/msystems.00053-23] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Accepted: 02/15/2023] [Indexed: 03/18/2023] Open
Abstract
Chlamydia trachomatis is an obligate intracellular bacterium that progresses through an essential multicell form developmental cycle. Infection of the host is initiated by the elementary body (EB). Once in the host, the EB cell differentiates into the noninfectious, but replication-competent, reticulate body, or RB. After multiple rounds of replication, RBs undergo secondary differentiation, eventually producing newly infectious EBs. Here, we generated paired cell-type promoter reporter constructs and determined the kinetics of the activities of the euo, hctA, and hctB promoters. The paired constructs revealed that the developmental cycle produces at least three phenotypically distinct cell types, the RB (euoprom+), intermediate body (IB; hctAprom+), and EB (hctBprom+). The kinetic data from the three dual-promoter constructs were used to generate two computational agent-based models to reproduce the chlamydial developmental cycle. Both models simulated EB germination, RB amplification, IB formation, and EB production but differed in the mechanism that generated the IB. The direct conversion and the asymmetric production models predicted different behaviors for the RB population, which were experimentally testable. In agreement with the asymmetric production model, RBs acted as stem cells after the initial amplification stage, producing one IB and self-renewing after every division. We also demonstrated that IBs are a transient cell population, maturing directly into EBs after formation without the need for cell division. The culmination of these results suggests that the developmental cycle can be described by a four-stage model, EB germination, RB amplification/maturation, IB production, and EB formation. IMPORTANCE Chlamydia trachomatis is an obligate intracellular bacterial pathogen responsible for both ocular and sexually transmitted infections. All Chlamydiae are reliant on a complex developmental cycle, consisting of both infectious and noninfectious cell forms. The EB cell form initiates infection, whereas the RB cell replicates. The infectious cycle requires both cell types, as RB replication increases the cell population while EB formation disseminates the infection to new hosts. The mechanisms of RB-to-EB development are largely unknown. Here, we developed unique dual promoter reporters and used live-cell imaging and confocal microscopy to visualize the cycle at the single-cell and kinetic levels. These data were used to develop and test two agent-based models, simulating either direct conversion of RBs to EBs or production of EBs via asymmetric RB division. Our results suggest that RBs mature into a stem cell-like population producing intermediate cell forms through asymmetric division, followed by maturation of the intermediate cell type into the infectious EB. Ultimately, a more complete mechanistic understanding of the developmental cycle will lead to novel therapeutics targeting cell type development to eliminate chlamydial dissemination.
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Affiliation(s)
| | | | - Cody Appa
- Department of Biological Sciences, University of Idaho, Moscow, Idaho, USA
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Götz R, Kunz TC, Fink J, Solger F, Schlegel J, Seibel J, Kozjak-Pavlovic V, Rudel T, Sauer M. Nanoscale imaging of bacterial infections by sphingolipid expansion microscopy. Nat Commun 2020; 11:6173. [PMID: 33268771 PMCID: PMC7710728 DOI: 10.1038/s41467-020-19897-1] [Citation(s) in RCA: 39] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Accepted: 11/05/2020] [Indexed: 12/20/2022] Open
Abstract
Expansion microscopy (ExM) enables super-resolution imaging of proteins and nucleic acids on conventional microscopes. However, imaging of details of the organization of lipid bilayers by light microscopy remains challenging. We introduce an unnatural short-chain azide- and amino-modified sphingolipid ceramide, which upon incorporation into membranes can be labeled by click chemistry and linked into hydrogels, followed by 4× to 10× expansion. Confocal and structured illumination microscopy (SIM) enable imaging of sphingolipids and their interactions with proteins in the plasma membrane and membrane of intracellular organelles with a spatial resolution of 10–20 nm. As our functionalized sphingolipids accumulate efficiently in pathogens, we use sphingolipid ExM to investigate bacterial infections of human HeLa229 cells by Neisseria gonorrhoeae, Chlamydia trachomatis and Simkania negevensis with a resolution so far only provided by electron microscopy. In particular, sphingolipid ExM allows us to visualize the inner and outer membrane of intracellular bacteria and determine their distance to 27.6 ± 7.7 nm. Imaging of lipid bilayers using light microscopy is challenging. Here the authors label cells using a short chain click-compatible ceramide to visualize mammalian and bacterial membranes with expansion microscopy.
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Affiliation(s)
- Ralph Götz
- Department of Biotechnology and Biophysics, Biocenter, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Tobias C Kunz
- Department of Microbiology, Biocenter, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Julian Fink
- Institute for Organic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Franziska Solger
- Department of Microbiology, Biocenter, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Jan Schlegel
- Department of Biotechnology and Biophysics, Biocenter, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Jürgen Seibel
- Institute for Organic Chemistry, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Vera Kozjak-Pavlovic
- Department of Microbiology, Biocenter, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany
| | - Thomas Rudel
- Department of Microbiology, Biocenter, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany.
| | - Markus Sauer
- Department of Biotechnology and Biophysics, Biocenter, Julius-Maximilians-Universität Würzburg, Am Hubland, 97074, Würzburg, Germany.
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3
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Abstract
Chlamydia trachomatis is an obligate intracellular bacterium that can cause trachoma, cervicitis, urethritis, salpingitis, and pelvic inflammatory disease. To establish infection in host cells, Chlamydia must complete a multiple-cell-type developmental cycle. The developmental cycle consists of specialized cells, the EB cell, which mediates infection of new host cells, and the RB cell, which replicates and eventually produces more EB cells to mediate the next round of infection. By developing and testing mathematical models to discriminate between two competing hypotheses for the nature of the signal controlling RB-to-EB cell type switching, we demonstrate that RB-to-EB development follows a cell-autonomous program that does not respond to environmental cues. Additionally, we show that RB-to-EB development is a function of chlamydial growth and division. This study serves to further our understanding of the chlamydial developmental cycle that is central to the bacterium’s pathogenesis. The obligate intracellular bacterial pathogen Chlamydia trachomatis is reliant on a developmental cycle consisting of two cell forms, termed the elementary body (EB) and the reticulate body (RB). The EB is infectious and utilizes a type III secretion system and preformed effector proteins during invasion, but it does not replicate. The RB replicates in the host cell but is noninfectious. This developmental cycle is central to chlamydial pathogenesis. In this study, we developed mathematical models of the developmental cycle that account for potential factors influencing RB-to-EB cell type switching during infection. Our models predicted that two categories of regulatory signals for RB-to-EB development could be differentiated experimentally, an “intrinsic” cell-autonomous program inherent to each RB and an “extrinsic” environmental signal to which RBs respond. To experimentally differentiate between mechanisms, we tracked the expression of C. trachomatis development-specific promoters in individual inclusions using fluorescent reporters and live-cell imaging. These experiments indicated that EB production was not influenced by increased multiplicity of infection or by superinfection, suggesting the cycle follows an intrinsic program that is not directly controlled by environmental factors. Additionally, live-cell imaging revealed that EB development is a multistep process linked to RB growth rate and cell division. The formation of EBs followed a progression with expression from the euo and ihtA promoters evident in RBs, while expression from the promoter for hctA was apparent in early EBs/IBs. Finally, expression from the promoters for the true late genes, hctB, scc2, and tarp, was evident in the maturing EB. IMPORTANCEChlamydia trachomatis is an obligate intracellular bacterium that can cause trachoma, cervicitis, urethritis, salpingitis, and pelvic inflammatory disease. To establish infection in host cells, Chlamydia must complete a multiple-cell-type developmental cycle. The developmental cycle consists of specialized cells, the EB cell, which mediates infection of new host cells, and the RB cell, which replicates and eventually produces more EB cells to mediate the next round of infection. By developing and testing mathematical models to discriminate between two competing hypotheses for the nature of the signal controlling RB-to-EB cell type switching, we demonstrate that RB-to-EB development follows a cell-autonomous program that does not respond to environmental cues. Additionally, we show that RB-to-EB development is a function of chlamydial growth and division. This study serves to further our understanding of the chlamydial developmental cycle that is central to the bacterium’s pathogenesis.
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Banhart S, Rose L, Aeberhard L, Koch-Edelmann S, Heuer D. Chlamydia trachomatis and its interaction with the cellular retromer. Int J Med Microbiol 2017; 308:197-205. [PMID: 29122514 DOI: 10.1016/j.ijmm.2017.10.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2017] [Revised: 10/16/2017] [Accepted: 10/24/2017] [Indexed: 11/26/2022] Open
Abstract
Chlamydia trachomatis is an important human pathogen. This obligate intracellular bacterium grows inside the eukaryotic cell in a membrane-bound compartment, the inclusion. Recent global approaches describe the interactions of C. trachomatis with its host cell and indicate the inclusion is an intracellular trafficking hub embedded into the cellular vesicular trafficking pathways recruiting subunits of the retromer protein complex of the host cell. Here we review these recent developments in deciphering Chlamydia-host cell interactions with emphasis on the role of the retromer complex.
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Affiliation(s)
- Sebastian Banhart
- Division "Sexually Transmitted Bacterial Infections" (FG 19), Robert Koch Institute, Berlin, Germany
| | - Laura Rose
- Division "Sexually Transmitted Bacterial Infections" (FG 19), Robert Koch Institute, Berlin, Germany
| | - Lukas Aeberhard
- Division "Sexually Transmitted Bacterial Infections" (FG 19), Robert Koch Institute, Berlin, Germany
| | - Sophia Koch-Edelmann
- Division "Sexually Transmitted Bacterial Infections" (FG 19), Robert Koch Institute, Berlin, Germany
| | - Dagmar Heuer
- Division "Sexually Transmitted Bacterial Infections" (FG 19), Robert Koch Institute, Berlin, Germany.
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Zigangirova NA, Kost EA, Didenko LV, Kapotina LN, Zayakin ES, Luyksaar SI, Morgunova EY, Fedina ED, Artyukhova OA, Samorodov AV, Kobets NV. A small-molecule compound belonging to a class of 2,4-disubstituted 1,3,4-thiadiazine-5-ones inhibits intracellular growth and persistence of Chlamydia trachomatis. J Med Microbiol 2016; 65:91-98. [PMID: 26489840 DOI: 10.1099/jmm.0.000189] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Chlamydia trachomatis is one of the most common sexually transmitted pathogens in the world and often causes chronic inflammatory diseases that are insensitive to antibiotics. The type 3 secretion system (T3SS) of pathogenic bacteria is a promising target for therapeutic intervention aimed at bacterial virulence and can be an attractive alternative for the treatment of chronic infections. Recently, we have shown that a small-molecule compound belonging to a class of 2,4-disubstituted 1,3,4-thiadiazine-5-ones produced through the chemical modification of the thiohydrazides of oxamic acids, designated CL-55, inhibited the intracellular growth of C. trachomatis in a T3SS-dependent manner. To assess the feasibility of CL-55 as a therapeutic agent, our aim was to determine which point(s) in the developmental cycle CL-55 affects. We found that CL-55 had no effect on the adhesion of elementary bodies (EBs) to host cells but significantly suppressed EB internalization. We further found that CL-55 inhibited the intracellular division of reticulate bodies (RBs). An ultrastructural analysis revealed loss of contact between the RBs and the inclusion membrane in the presence of CL-55. Finally, we found that our T3SS inhibitor prevented the persistence of Chlamydia in cell culture and its reversion to the infectious state. Our findings indicate that our T3SS inhibitor may be effective in the treatment of both productive and persistent infections.
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Affiliation(s)
- Naylia A Zigangirova
- Gamaleya Center of Epidemiology and Microbiology, Ministry of Health Russian Federation, 123098, Gamaleya Str. 18, Moscow, Russian Federation
| | - Elena A Kost
- Gamaleya Center of Epidemiology and Microbiology, Ministry of Health Russian Federation, 123098, Gamaleya Str. 18, Moscow, Russian Federation
| | - Lubov V Didenko
- Gamaleya Center of Epidemiology and Microbiology, Ministry of Health Russian Federation, 123098, Gamaleya Str. 18, Moscow, Russian Federation
| | - Lydia N Kapotina
- Gamaleya Center of Epidemiology and Microbiology, Ministry of Health Russian Federation, 123098, Gamaleya Str. 18, Moscow, Russian Federation
| | - Egor S Zayakin
- Gamaleya Center of Epidemiology and Microbiology, Ministry of Health Russian Federation, 123098, Gamaleya Str. 18, Moscow, Russian Federation
| | - Sergei I Luyksaar
- Gamaleya Center of Epidemiology and Microbiology, Ministry of Health Russian Federation, 123098, Gamaleya Str. 18, Moscow, Russian Federation
| | - Elena Y Morgunova
- Gamaleya Center of Epidemiology and Microbiology, Ministry of Health Russian Federation, 123098, Gamaleya Str. 18, Moscow, Russian Federation
| | - Elena D Fedina
- Gamaleya Center of Epidemiology and Microbiology, Ministry of Health Russian Federation, 123098, Gamaleya Str. 18, Moscow, Russian Federation
| | - Olga A Artyukhova
- Bauman Moscow State Technical University, 105005, 2nd Baumanskaya Str. 5, Moscow, Russian Federation
| | - Andrey V Samorodov
- Bauman Moscow State Technical University, 105005, 2nd Baumanskaya Str. 5, Moscow, Russian Federation
| | - Natalya V Kobets
- Gamaleya Center of Epidemiology and Microbiology, Ministry of Health Russian Federation, 123098, Gamaleya Str. 18, Moscow, Russian Federation
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Dumoux M, Menny A, Delacour D, Hayward RD. A Chlamydia effector recruits CEP170 to reprogram host microtubule organization. J Cell Sci 2015. [PMID: 26220855 PMCID: PMC4582400 DOI: 10.1242/jcs.169318] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The obligate intracellular bacterial pathogen Chlamydia trachomatis deploys virulence effectors to subvert host cell functions enabling its replication within a specialized membrane-bound compartment termed an inclusion. The control of the host cytoskeleton is crucial for Chlamydia uptake, inclusion biogenesis and cell exit. Here, we demonstrate how a Chlamydia effector rearranges the microtubule (MT) network by initiating organization of the MTs at the inclusion surface. We identified an inclusion-localized effector that is sufficient to interfere with MT assembly, which we named inclusion protein acting on MTs (IPAM). We established that IPAM recruits and stimulates the centrosomal protein 170 kDa (CEP170) to hijack the MT organizing functions of the host cell. We show that CEP170 is essential for chlamydial control of host MT assembly, and is required for inclusion morphogenesis and bacterial infectivity. Together, we demonstrate how a pathogen effector reprograms the host MT network to support its intracellular development.
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Affiliation(s)
- Maud Dumoux
- Institute of Structural and Molecular Biology, Birkbeck and University College London, Malet Street, London WC1E 7HX, UK
| | - Anais Menny
- Institute of Structural and Molecular Biology, Birkbeck and University College London, Malet Street, London WC1E 7HX, UK
| | - Delphine Delacour
- Cell Adhesion and Mechanics Group, Institut Jacques Monod, CNRS UMR7592, Université Paris Diderot, 15 rue Helene Brion, Paris 75013, France
| | - Richard D Hayward
- Institute of Structural and Molecular Biology, Birkbeck and University College London, Malet Street, London WC1E 7HX, UK
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7
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Käding N, Szaszák M, Rupp J. Imaging of Chlamydia and host cell metabolism. Future Microbiol 2014; 9:509-21. [DOI: 10.2217/fmb.14.13] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
ABSTRACT: Chlamydial infections cause a wide range of acute and chronic diseases. Chlamydia trachomatis is the most common sexually transmitted bacterium while Chlamydia pneumoniae causes infections of the upper and lower respiratory tract. Chlamydia are obligate, intracellular bacteria with a biphasic developmental cycle that involves unique metabolic changes. Aside from entering an actively replicating state, Chlamydia may also implement persistent infections depending on different microenvironmental factors. In addition, changes in local oxygen availability and the composition of surrounding host microbiota are suggested to affect chlamydial growth and metabolism. Both bacteria and host cells endure characteristic metabolic changes during infection. Technical developments in recent years enable us to separately characterize chlamydial and host cell metabolism in living cells. This article focuses on novel approaches to analyze chlamydial metabolism such as NAD(P)H fluorescence lifetime imaging by two-photon microscopy. In addition, we provide an overview regarding promising future possibilities to further elucidate host–pathogen metabolic interactions.
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Affiliation(s)
- Nadja Käding
- Institute of Medical Microbiology & Hygiene, University of Lübeck, Ratzeburger Allee 160, 23538 Lübeck, Germany
| | - Márta Szaszák
- Institute of Medical Microbiology & Hygiene, University of Lübeck, Ratzeburger Allee 160, 23538 Lübeck, Germany
| | - Jan Rupp
- Institute of Medical Microbiology & Hygiene, University of Lübeck, Ratzeburger Allee 160, 23538 Lübeck, Germany
- Medical Clinic III/University Hospital Schleswig-Holstein, Campus Lübeck, Ratzeburger Allee 160, 23538 Lübeck, Germany
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8
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A Mathematical Model of Chlamydial Infection Incorporating Movement of Chlamydial Particles. Bull Math Biol 2013; 75:2257-70. [DOI: 10.1007/s11538-013-9891-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2013] [Accepted: 07/25/2013] [Indexed: 11/26/2022]
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9
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Mutations in hemG mediate resistance to salicylidene acylhydrazides, demonstrating a novel link between protoporphyrinogen oxidase (HemG) and Chlamydia trachomatis infectivity. J Bacteriol 2013; 195:4221-30. [PMID: 23852872 DOI: 10.1128/jb.00506-13] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Salicylidene acylhydrazides (SAHs) inhibit the type III secretion system (T3S) of Yersinia and other Gram-negative bacteria. In addition, SAHs restrict the growth and development of Chlamydia species. However, since the inhibition of Chlamydia growth by SAH is suppressed by the addition of excess iron and since SAHs have an iron-chelating capacity, their role as specific T3S inhibitors is unclear. We investigated here whether SAHs exhibit a function on C. trachomatis that goes beyond iron chelation. We found that the iron-saturated SAH INP0341 (IS-INP0341) specifically affects C. trachomatis infectivity with reduced generation of infectious elementary body (EB) progeny. Selection and isolation of spontaneous SAH-resistant mutant strains revealed that mutations in hemG suppressed the reduced infectivity caused by IS-INP0341 treatment. Structural modeling of C. trachomatis HemG predicts that the acquired mutations are located in the active site of the enzyme, suggesting that IS-INP0341 inhibits this domain of HemG and that protoporphyrinogen oxidase (HemG) and heme metabolism are important for C. trachomatis infectivity.
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10
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Markkula E, Hulkkonen J, Penttilä T, Puolakkainen M. Host cell Golgi anti-apoptotic protein (GAAP) and growth of Chlamydia pneumoniae. Microb Pathog 2013; 54:46-53. [DOI: 10.1016/j.micpath.2012.09.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Revised: 09/03/2012] [Accepted: 09/10/2012] [Indexed: 01/01/2023]
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Roulis E, Polkinghorne A, Timms P. Chlamydia pneumoniae: modern insights into an ancient pathogen. Trends Microbiol 2012; 21:120-8. [PMID: 23218799 DOI: 10.1016/j.tim.2012.10.009] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2012] [Revised: 10/28/2012] [Accepted: 10/31/2012] [Indexed: 01/11/2023]
Abstract
Chlamydia pneumoniae is an enigmatic human and animal pathogen. Originally discovered in association with acute human respiratory disease, it is now associated with a remarkably wide range of chronic diseases as well as having a cosmopolitan distribution within the animal kingdom. Molecular typing studies suggest that animal strains are ancestral to human strains and that C. pneumoniae crossed from animals to humans as the result of at least one relatively recent zoonotic event. Whole genome analyses appear to support this concept - the human strains are highly conserved whereas the single animal strain that has been fully sequenced has a larger genome with several notable differences. When compared to the other, better known chlamydial species that is implicated in human infection, Chlamydia trachomatis, C. pneumoniae demonstrates pertinent differences in its cell biology, development, and genome structure. Here, we examine the characteristic facets of C. pneumoniae biology, offering insights into the diversity and evolution of this silent and ancient pathogen.
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Affiliation(s)
- Eileen Roulis
- Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane 4059, Australia
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12
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Zigangirova NA, Nesterenko LN, Tiganova IL, Kost EA. The role of the type-III secretion system of Gram-negative bacteria in the regulation of chronic infections. MOLECULAR GENETICS, MICROBIOLOGY AND VIROLOGY 2012. [DOI: 10.3103/s0891416812030081] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/10/2023]
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13
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Zigangirova N, Zayakin E, Kapotina L, Kost E, Didenko L, Davydova D, Rumyanceva J, Gintsburg A. Development of Chlamydial Type III Secretion System Inhibitors for Suppression of Acute and Chronic Forms of Chlamydial Infection. Acta Naturae 2012; 4:87-97. [PMID: 22880162 PMCID: PMC3411183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/29/2022] Open
Abstract
The Type III secretion system (T3SS) is currently considered to be one of the main pathogenicity factors in Gram-negative bacteria, which exhibit different types of parasitizing activity. The presence of this structure is essential for the development of an acute infection; the chronicity of the infection is fundamentally dependent upon its functioning. In this regard, T3TS is one of the most promising targets for the development of broad-spectrum antimicrobial drugs that do not develop resistance and are efficacious for the acute and chronic forms of infection. The mechanism of action in drug development is based on the specific inhibition of T3SS, which should interrupt the infectious process, thereby enabling the immune system to eliminate the pathogen. As a result of pilot screening using specific cellular and bacterial tests, followed by chemical optimization and detailed characterization of the biological activity, a new class of chlamydial T3SS inhibitors was obtained. The selected compounds have obvious advantages over the currently available inhibitors of T3SS pathogens thanks to the high inhibitory activity of these compounds with minimal damaging effects on eukaryotic cells. Preclinical trials of the selected inhibitors are currently under way.
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Affiliation(s)
| | - E.S. Zayakin
- Gamaleya Research Institute of Epidemiology and Microbiology
| | - L.N. Kapotina
- Gamaleya Research Institute of Epidemiology and Microbiology
| | - E.A. Kost
- Gamaleya Research Institute of Epidemiology and Microbiology
| | - L.V. Didenko
- Gamaleya Research Institute of Epidemiology and Microbiology
| | - D.Y. Davydova
- Gamaleya Research Institute of Epidemiology and Microbiology
| | - J.P. Rumyanceva
- Gamaleya Research Institute of Epidemiology and Microbiology
| | - A.L. Gintsburg
- Gamaleya Research Institute of Epidemiology and Microbiology
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14
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Stone CB, Sugiman-Marangos S, Bulir DC, Clayden RC, Leighton TL, Slootstra JW, Junop MS, Mahony JB. Structural characterization of a novel Chlamydia pneumoniae type III secretion-associated protein, Cpn0803. PLoS One 2012; 7:e30220. [PMID: 22272312 PMCID: PMC3260263 DOI: 10.1371/journal.pone.0030220] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2011] [Accepted: 12/15/2011] [Indexed: 01/07/2023] Open
Abstract
Type III secretion (T3S) is an essential virulence factor used by gram-negative pathogenic bacteria to deliver effector proteins into the host cell to establish and maintain an intracellular infection. Chlamydia is known to use T3S to facilitate invasion of host cells but many proteins in the system remain uncharacterized. The C. trachomatis protein CT584 has previously been implicated in T3S. Thus, we analyzed the CT584 ortholog in C. pneumoniae (Cpn0803) and found that it associates with known T3S proteins including the needle-filament protein (CdsF), the ATPase (CdsN), and the C-ring protein (CdsQ). Using membrane lipid strips, Cpn0803 interacted with phosphatidic acid and phosphatidylinositol, suggesting that Cpn0803 may associate with host cells. Crystallographic analysis revealed a unique structure of Cpn0803 with a hydrophobic pocket buried within the dimerization interface that may be important for binding small molecules. Also, the binding domains on Cpn0803 for CdsN, CdsQ, and CdsF were identified using Pepscan epitope mapping. Collectively, these data suggest that Cpn0803 plays a role in T3S.
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Affiliation(s)
- Chris B. Stone
- M. G. DeGroote Institute for Infectious Disease Research, Faculty of Health Sciences and the Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Canada
- Father Sean O'Sullivan Research Centre, St. Joseph's Healthcare, Hamilton, Canada
| | - Seiji Sugiman-Marangos
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Canada
| | - David C. Bulir
- M. G. DeGroote Institute for Infectious Disease Research, Faculty of Health Sciences and the Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Canada
- Father Sean O'Sullivan Research Centre, St. Joseph's Healthcare, Hamilton, Canada
| | - Rob C. Clayden
- M. G. DeGroote Institute for Infectious Disease Research, Faculty of Health Sciences and the Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Canada
- Father Sean O'Sullivan Research Centre, St. Joseph's Healthcare, Hamilton, Canada
| | - Tiffany L. Leighton
- M. G. DeGroote Institute for Infectious Disease Research, Faculty of Health Sciences and the Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Canada
- Father Sean O'Sullivan Research Centre, St. Joseph's Healthcare, Hamilton, Canada
| | | | - Murray S. Junop
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Canada
| | - James B. Mahony
- M. G. DeGroote Institute for Infectious Disease Research, Faculty of Health Sciences and the Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Canada
- Father Sean O'Sullivan Research Centre, St. Joseph's Healthcare, Hamilton, Canada
- * E-mail:
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15
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Stone CB, Bulir DC, Emdin CA, Pirie RM, Porfilio EA, Slootstra JW, Mahony JB. Chlamydia Pneumoniae CdsL Regulates CdsN ATPase Activity, and Disruption with a Peptide Mimetic Prevents Bacterial Invasion. Front Microbiol 2011; 2:21. [PMID: 21687413 PMCID: PMC3109343 DOI: 10.3389/fmicb.2011.00021] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2010] [Accepted: 01/30/2011] [Indexed: 12/29/2022] Open
Abstract
Chlamydiae are obligate intracellular pathogens that likely require type III secretion (T3S) to invade cells and replicate intracellularly within a cytoplasmic vacuole called an inclusion body. Chlamydia pneumoniae possess a YscL ortholog, CdsL, that has been shown to interact with the T3S ATPase (CdsN). In this report we demonstrate that CdsL down-regulates CdsN enzymatic activity in a dose-dependent manner. Using Pepscan epitope mapping we identified two separate binding domains to which CdsL binds viz. CdsN221–229 and CdsN265–270. We confirmed the binding domains using a pull-down assay and showed that GST–CdsN221–270, which encompasses these peptides, co-purified with His–CdsL. Next, we used orthology modeling based on the crystal structure of a T3S ATPase ortholog from Escherichia coli, EscN, to map the binding domains on the predicted 3D structure of CdsN. The CdsL binding domains mapped to the catalytic domain of the ATPase, one in the central channel of the ATPase hexamer and one on the outer face. Since peptide mimetics have been used to disrupt essential protein interactions of the chlamydial T3S system and inhibit T3S-mediated invasion of HeLa cells, we hypothesized that if CdsL–CdsN binding is essential for regulating T3S then a CdsN peptide mimetic could be used to potentially block T3S and chlamydial invasion. Treatment of elementary body with a CdsN peptide mimetic inhibited C. pneumoniae invasion into HeLa cells in a dose-dependent fashion. This report represents the first use of Pepscan technology to identify binding domains for specific T3S proteins viz. CdsL on the ATPase, CdsN, and demonstrates that peptide mimetics can be used as anti-virulence factors to block bacterial invasion.
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Affiliation(s)
- Chris B Stone
- Michael G. DeGroote Institute for Infectious Disease Research, Faculty of Health Sciences, Department of Pathology and Molecular Medicine, McMaster University, Father Sean O'Sullivan Research Centre, St. Joseph's Healthcare Hamilton, ON, Canada
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Abstract
Bacteria can exist in metabolically inactive states that allow them to survive conditions that are not conducive for growth. Such dormant cells may sense when conditions have improved and re-initiate growth, lest they be outcompeted by their neighbours. Growing bacteria turn over and release large quantities of their cell walls into the environment. Drawing from recent work on the germination of Bacillus subtilis spores, we propose that many microorganisms exit dormancy in response to cell wall muropeptides.
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Stone CB, Bulir DC, Gilchrist JD, Toor RK, Mahony JB. Interactions between flagellar and type III secretion proteins in Chlamydia pneumoniae. BMC Microbiol 2010; 10:18. [PMID: 20096108 PMCID: PMC2830194 DOI: 10.1186/1471-2180-10-18] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2009] [Accepted: 01/22/2010] [Indexed: 11/30/2022] Open
Abstract
Background Flagellar secretion systems are utilized by a wide variety of bacteria to construct the flagellum, a conserved apparatus that allows for migration towards non-hostile, nutrient rich environments. Chlamydia pneumoniae is an obligate, intracellular pathogen whose genome contains at least three orthologs of flagellar proteins, namely FliI, FlhA and FliF, but the role of these proteins remains unknown. Results Full length FliI, and fragments of FlhA, FliF, and FliI, were cloned and expressed as either GST or His tagged proteins in E. coli. The GST-tagged full length FliI protein was shown to possess ATPase activity, hydrolyzing ATP at a rate of 0.15 ± .02 μmol min-1 mg-1 in a time- and dose-dependant manner. Using bacterial-2-hybrid and GST pull-down assays, the N-terminal domain of FliI was shown to interact with the cytoplasmic domain of FlhA, but not with FliF, and the cytoplasmic domain of FlhA was shown to interact with the C-terminus of FliF. The absence of other flagellar orthologs led us to explore cross-reaction of flagellar proteins with type III secretion proteins, and we found that FliI interacted with CdsL and CopN, while FlhA interacted with CdsL and Cpn0322 (YscU ortholog CdsU). Conclusions The specific interaction of the four orthologous flagellar proteins in C. pneumoniae suggests that they interact in vivo and, taken together with their conservation across members of the chlamydiae sps., and their interaction with T3S components, suggests a role in bacterial replication and/or intracellular survival.
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Affiliation(s)
- Chris B Stone
- M,G, DeGroote Institute for Infectious Disease Research, Faculty of Health Sciences and the Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Ontario, Canada
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Pettengill MA, Lam VW, Ojcius DM. The danger signal adenosine induces persistence of chlamydial infection through stimulation of A2b receptors. PLoS One 2009; 4:e8299. [PMID: 20011598 PMCID: PMC2788228 DOI: 10.1371/journal.pone.0008299] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2009] [Accepted: 11/08/2009] [Indexed: 11/18/2022] Open
Abstract
Infections with intracellular bacteria such as chlamydiae affect the majority of the world population. Infected tissue inflammation and granuloma formation help contain the short-term expansion of the invading pathogen, leading also to local tissue damage and hypoxia. However, the effects of key aspects of damaged inflamed tissues and hypoxia on continued infection with intracellular bacteria remain unknown. We find that development of Chlamydia trachomatis is reversibly retarded by prolonged exposure of infected cells to extracellular adenosine, a hallmark of hypoxia and advanced inflammation. In epithelial cells, this effect was mediated by the A2b adenosine receptor, unique in the adenosine receptor family for having a hypoxia-inducible factor (HIF1-α) binding site at its promoter region, and was dependent on an increase in the intracellular cAMP levels, but was independent of cAMP-dependent protein kinase (PKA). Further study of adenosine receptor signaling during intracellular bacterial infection could lead to breakthroughs in our understanding of persistent infections with these ubiquitous pathogens.
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Affiliation(s)
- Matthew A Pettengill
- Health Sciences Research Institute and School of Natural Sciences, University of California Merced, Merced, California, United States of America
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Troese MJ, Carlyon JA. Anaplasma phagocytophilum dense-cored organisms mediate cellular adherence through recognition of human P-selectin glycoprotein ligand 1. Infect Immun 2009; 77:4018-27. [PMID: 19596771 PMCID: PMC2738047 DOI: 10.1128/iai.00527-09] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2009] [Revised: 06/08/2009] [Accepted: 07/07/2009] [Indexed: 01/20/2023] Open
Abstract
Anaplasma phagocytophilum is an obligate intracellular bacterium that infects granulocytes to cause human granulocytic anaplasmosis. The susceptibilities of human neutrophils and promyelocytic HL-60 cells to A. phagocytophilum are linked to bacterial usage of P-selectin glycoprotein ligand 1 (PSGL-1) as a receptor for adhesion and entry. A. phagocytophilum undergoes a biphasic developmental cycle, transitioning between a smaller electron dense-cored cell (DC), which has a dense nucleoid, and a larger, pleomorphic electron lucent reticulate cell (RC), which has a dispersed nucleoid. The pathobiological roles of each form have not been elucidated. To ascertain the role of each form, we used electron microscopy to monitor bacterial binding, entry, and intracellular development within HL-60 cells. Only DCs were observed binding to and inducing uptake by HL-60 cells. By 12 h, internalized DCs had transitioned to RCs, which had initiated replication. By 24 h, large RC numbers were observed within individual inclusions. Reinfection had occurred by 36 h, as individual, vacuole-enclosed DCs and RCs were again observed. The abilities of DC- and RC-enriched A. phagocytophilum populations to bind and/or infect HL-60 cells or Chinese hamster ovary cells transfected to express PSGL-1 (PSGL-1 CHO) were compared. Only DCs bound PSGL-1 CHO cells and did so in a PSGL-1-blocking antibody-inhibitable manner. These results demonstrate that the respective roles of A. phagocytophilum DCs and RCs are consistent with analogous forms of other obligate intracellular pathogens that undergo biphasic development and hint that the PSGL-1-targeting adhesin(s) may be upregulated or optimally posttranslationally modified on DCs.
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Affiliation(s)
- Matthew J Troese
- Department of Microbiology and Immunology, Virginia Commonwealth University School of Medicine, Richmond, Virginia 23298-0678, USA
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Kinematics of intracellular chlamydiae provide evidence for contact-dependent development. J Bacteriol 2009; 191:5734-42. [PMID: 19542292 DOI: 10.1128/jb.00293-09] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
A crucial process of chlamydial development involves differentiation of the replicative reticulate body (RB) into the infectious elementary body (EB). We present experimental evidence to provide support for a contact-dependent hypothesis for explaining the trigger involved in differentiation. We recorded live-imaging of Chlamydia trachomatis-infected McCoy cells at key times during development and tracked the temporospatial trajectories of individual chlamydial particles. We found that movement of the particles is related to development. Early to mid-developmental stages involved slight wobbling of RBs. The average speed of particles increased sharply at 24 h postinfection (after the estimated onset of RB to EB differentiation). We also investigated a penicillin-supplemented culture containing EBs, RBs, and aberrantly enlarged, stressed chlamydiae. Near-immobile enlarged particles are consistent with their continued tethering to the chlamydial inclusion membrane (CIM). We found a significantly negative, nonlinear association between speed and size/type of particles, providing further support for the hypothesis that particles become untethered near the onset of RB to EB differentiation. This study establishes the relationship between the motion properties of the chlamydiae and developmental stages, whereby wobbling RBs gradually lose contact with the CIM, and RB detachment from the CIM is coincidental with the onset of late differentiation.
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Characterization of the putative type III secretion ATPase CdsN (Cpn0707) of Chlamydophila pneumoniae. J Bacteriol 2008; 190:6580-8. [PMID: 18708502 DOI: 10.1128/jb.00761-08] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Type III secretion (T3S) is utilized by a wide range of gram-negative bacterial pathogens to allow the efficient delivery of effector proteins into the host cell cytoplasm through the use of a syringe-like injectisome. Chlamydophila pneumoniae is a gram-negative, obligate intracellular pathogen that has the structural genes coding for a T3S system, but the functionality of the system has not yet been demonstrated. T3S is dependent on ATPase activity, which catalyzes the unfolding of proteins and the secretion of effector proteins through the injectisome. CdsN (Cpn0707) is predicted to be the T3S ATPase of C. pneumoniae based on sequence similarity to other T3S ATPases. Full-length CdsN and a C-terminal truncation of CdsN were cloned as glutathione S-transferase (GST)-tagged constructs and expressed in Escherichia coli. The GST-tagged C-terminal truncation of CdsN possessed ATPase activity, catalyzing the release of ADP and P(i) from ATP at a rate of 0.55 +/- 0.07 micromol min(-1) mg(-1) in a time- and dose-dependent manner. CdsN formed oligomers and high-molecular-weight multimers, as assessed by formaldehyde fixation and nondenaturing polyacrylamide gel electrophoresis. Using bacterial two-hybrid and GST pull-down assays, CdsN was shown to interact with CdsD, CdsL, CdsQ, and CopN, four putative structural components of the C. pneumoniae T3S system. CdsN also interacted with an unannotated protein, Cpn0706, a putative CdsN chaperone. Interactions between CdsN, CdsD, and CopN represent novel interactions not previously reported for other bacterial T3S systems and may be important in the localization and/or function of the ATPase at the inner membrane of C. pneumoniae.
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