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Chlamydia Uses K + Electrical Signalling to Orchestrate Host Sensing, Inter-Bacterial Communication and Differentiation. Microorganisms 2021; 9:microorganisms9010173. [PMID: 33467438 PMCID: PMC7830353 DOI: 10.3390/microorganisms9010173] [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: 12/16/2020] [Revised: 01/08/2021] [Accepted: 01/08/2021] [Indexed: 12/30/2022] Open
Abstract
Prokaryotic communities coordinate quorum behaviour in response to external stimuli to control fundamental processes including inter-bacterial communication. The obligate intracellular bacterial pathogen Chlamydia adopts two developmental forms, invasive elementary bodies (EBs) and replicative reticulate bodies (RBs), which reside within a specialised membrane-bound compartment within the host cell termed an inclusion. The mechanisms by which this bacterial community orchestrates different stages of development from within the inclusion in coordination with the host remain elusive. Both prokaryotic and eukaryotic kingdoms exploit ion-based electrical signalling for fast intercellular communication. Here we demonstrate that RBs specifically accumulate potassium (K+) ions, generating a gradient. Disruption of this gradient using ionophores or an ion-channel inhibitor stalls the Chlamydia lifecycle, inducing persistence. Using photobleaching approaches, we establish that the RB is the master regulator of this [K+] differential and observe a fast K+ exchange between RBs revealing a role for this ion in inter-bacterial communication. Finally, we demonstrate spatio-temporal regulation of bacterial membrane potential during RB to EB differentiation within the inclusion. Together, our data reveal that Chlamydia harnesses K+ to orchestrate host sensing, inter-bacteria communication and pathogen differentiation.
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Szulc-Dąbrowska L, Bossowska-Nowicka M, Struzik J, Toka FN. Cathepsins in Bacteria-Macrophage Interaction: Defenders or Victims of Circumstance? Front Cell Infect Microbiol 2020; 10:601072. [PMID: 33344265 PMCID: PMC7746538 DOI: 10.3389/fcimb.2020.601072] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 11/05/2020] [Indexed: 02/06/2023] Open
Abstract
Macrophages are the first encounters of invading bacteria and are responsible for engulfing and digesting pathogens through phagocytosis leading to initiation of the innate inflammatory response. Intracellular digestion occurs through a close relationship between phagocytic/endocytic and lysosomal pathways, in which proteolytic enzymes, such as cathepsins, are involved. The presence of cathepsins in the endo-lysosomal compartment permits direct interaction with and killing of bacteria, and may contribute to processing of bacterial antigens for presentation, an event necessary for the induction of antibacterial adaptive immune response. Therefore, it is not surprising that bacteria can control the expression and proteolytic activity of cathepsins, including their inhibitors – cystatins, to favor their own intracellular survival in macrophages. In this review, we summarize recent developments in defining the role of cathepsins in bacteria-macrophage interaction and describe important strategies engaged by bacteria to manipulate cathepsin expression and activity in macrophages. Particularly, we focus on specific bacterial species due to their clinical relevance to humans and animal health, i.e., Mycobacterium, Mycoplasma, Staphylococcus, Streptococcus, Salmonella, Shigella, Francisella, Chlamydia, Listeria, Brucella, Helicobacter, Neisseria, and other genera.
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Affiliation(s)
- Lidia Szulc-Dąbrowska
- Division of Immunology, Department of Preclinical Sciences, Institute of Veterinary Medicine, Warsaw University of Life Sciences-Szkoła Główna Gospodarstwa Wejskiego, Warsaw, Poland
| | - Magdalena Bossowska-Nowicka
- Division of Immunology, Department of Preclinical Sciences, Institute of Veterinary Medicine, Warsaw University of Life Sciences-Szkoła Główna Gospodarstwa Wejskiego, Warsaw, Poland
| | - Justyna Struzik
- Division of Immunology, Department of Preclinical Sciences, Institute of Veterinary Medicine, Warsaw University of Life Sciences-Szkoła Główna Gospodarstwa Wejskiego, Warsaw, Poland
| | - Felix N Toka
- Division of Immunology, Department of Preclinical Sciences, Institute of Veterinary Medicine, Warsaw University of Life Sciences-Szkoła Główna Gospodarstwa Wejskiego, Warsaw, Poland.,Center for Integrative Mammalian Research, Ross University School of Veterinary Medicine, Basseterre, Saint Kitts and Nevis
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Vu TH, Ha-Duong NT, Aubry A, Capton E, Fechter P, Plésiat P, Verbeke P, Serradji N. In vitro activities of a new fluoroquinolone derivative highly active against Chlamydia trachomatis. Bioorg Chem 2019; 83:180-185. [DOI: 10.1016/j.bioorg.2018.10.033] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Revised: 10/11/2018] [Accepted: 10/17/2018] [Indexed: 01/09/2023]
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Marti H, Borel N, Dean D, Leonard CA. Evaluating the Antibiotic Susceptibility of Chlamydia - New Approaches for in Vitro Assays. Front Microbiol 2018; 9:1414. [PMID: 30018602 PMCID: PMC6037721 DOI: 10.3389/fmicb.2018.01414] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Accepted: 06/08/2018] [Indexed: 11/13/2022] Open
Abstract
Pigs are the natural hosts of Chlamydia suis, the only Chlamydia species known to spontaneously acquire homotypic resistance conferred by a class C tetracycline resistance gene. Various susceptibility assays have existed for several years, but there is no widely accepted, standardized assay to determine chlamydial antibiotic susceptibility. In this study, we developed new approaches to determine the in vitro susceptibility of Chlamydia to different antibiotics in view of existing protocols. Specifically, the minimal inhibitory concentration (MIC) is based on a consensus of both inclusion number reduction and alteration of inclusion size and morphology upon antibiotic exposure. In addition to these, we employed a recovery assay, allowing observation of the chlamydial response to drug removal and subsequent recovery, as compared to both continued exposure and to the unexposed control. We propose a simple and fast screening method to detect tetracycline resistant C. suis strains within 2 to 3 days with minimal use of consumables. For proof of principle, we evaluated the susceptibility of three C. suis field strains and the reference strain S45/6 to tetracycline, sulfamethoxazole, and penicillin, antibiotics commonly used to prevent respiratory and gastrointestinal diseases on fattening pig farms. We found that tetracycline sensitive strains can easily be distinguished from resistant strains using the evaluation parameters proposed in this study. Moreover, we report that S45/6 is sensitive to sulfamethoxazole while all evaluated C. suis field strains showed some degree of sulfamethoxazole resistance. Finally, we confirm that Penicillin G induces the chlamydial stress response in all evaluated C. suis strains.
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Affiliation(s)
- Hanna Marti
- Institute of Veterinary Pathology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland.,Center for Immunobiology and Vaccine Development, UCSF Benioff Children's Hospital Oakland Research Institute, Oakland, CA, United States
| | - Nicole Borel
- Institute of Veterinary Pathology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
| | - Deborah Dean
- Center for Immunobiology and Vaccine Development, UCSF Benioff Children's Hospital Oakland Research Institute, Oakland, CA, United States.,Joint Graduate Program in Bioengineering, University of California, San Francisco, San Francisco, CA, United States.,Joint Graduate Program in Bioengineering, University of California, Berkeley, Berkeley, CA, United States.,School of Medicine, University of California, San Francisco, San Francisco, CA, United States
| | - Cory A Leonard
- Institute of Veterinary Pathology, Vetsuisse Faculty, University of Zurich, Zurich, Switzerland
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Leonard CA, Schoborg RV, Borel N. Productive and Penicillin-Stressed Chlamydia pecorum Infection Induces Nuclear Factor Kappa B Activation and Interleukin-6 Secretion In Vitro. Front Cell Infect Microbiol 2017; 7:180. [PMID: 28553623 PMCID: PMC5425588 DOI: 10.3389/fcimb.2017.00180] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2017] [Accepted: 04/25/2017] [Indexed: 11/13/2022] Open
Abstract
Nuclear factor kappa B (NFκB) is an inflammatory transcription factor that plays an important role in the host immune response to infection. The potential for chlamydiae to activate NFκB has been an area of interest, however most work has focused on chlamydiae impacting human health. Given that inflammation characteristic of chlamydial infection may be associated with severe disease outcomes or contribute to poor overall fitness in farmed animals, we evaluated the ability of porcine chlamydiae to induce NFκB activation in vitro. C. pecorum infection induced both NFκB nuclear translocation and activation at 2 hours post infection (hpi), an effect strongly enhanced by suppression of host de novo protein synthesis. C. suis and C. trachomatis showed less capacity for NFκB activation compared to C. pecorum, suggesting a species-specific variation in NFκB activation. At 24 hpi, C. pecorum induced significant NFκB activation, an effect not abolished by penicillin (beta lactam)-induced chlamydial stress. C. pecorum-dependent secretion of interleukin 6 was also detected in the culture supernatant of infected cells at 24 hpi, and this effect, too, was unchanged by penicillin-induced chlamydial stress. Taken together, these results suggest that NFκB participates in the early inflammatory response to C. pecorum and that stressed chlamydiae can promote inflammation.
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Affiliation(s)
- Cory A Leonard
- Department of Pathobiology, Institute of Veterinary Pathology, University of ZurichZurich, Switzerland
| | - Robert V Schoborg
- Department of Biomedical Sciences, Center for Inflammation, Infectious Disease and Immunity, James H. Quillen College of Medicine, East Tennessee State UniversityJohnson City, TN, USA
| | - Nicole Borel
- Department of Pathobiology, Institute of Veterinary Pathology, University of ZurichZurich, Switzerland
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Liechti G, Kuru E, Packiam M, Hsu YP, Tekkam S, Hall E, Rittichier JT, VanNieuwenhze M, Brun YV, Maurelli AT. Pathogenic Chlamydia Lack a Classical Sacculus but Synthesize a Narrow, Mid-cell Peptidoglycan Ring, Regulated by MreB, for Cell Division. PLoS Pathog 2016; 12:e1005590. [PMID: 27144308 PMCID: PMC4856321 DOI: 10.1371/journal.ppat.1005590] [Citation(s) in RCA: 73] [Impact Index Per Article: 9.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2015] [Accepted: 04/01/2016] [Indexed: 01/28/2023] Open
Abstract
The peptidoglycan (PG) cell wall is a peptide cross-linked glycan polymer essential for bacterial division and maintenance of cell shape and hydrostatic pressure. Bacteria in the Chlamydiales were long thought to lack PG until recent advances in PG labeling technologies revealed the presence of this critical cell wall component in Chlamydia trachomatis. In this study, we utilize bio-orthogonal D-amino acid dipeptide probes combined with super-resolution microscopy to demonstrate that four pathogenic Chlamydiae species each possess a ≤ 140 nm wide PG ring limited to the division plane during the replicative phase of their developmental cycles. Assembly of this PG ring is rapid, processive, and linked to the bacterial actin-like protein, MreB. Both MreB polymerization and PG biosynthesis occur only in the intracellular form of pathogenic Chlamydia and are required for cell enlargement, division, and transition between the microbe’s developmental forms. Our kinetic, molecular, and biochemical analyses suggest that the development of this limited, transient, PG ring structure is the result of pathoadaptation by Chlamydia to an intracellular niche within its vertebrate host. Pathogenic Chlamydia do not assemble their peptidoglycan (PG) cell wall in a classical, mesh-like sacculus, but instead apparently confine it to the mid-cell in the actively dividing, non-infectious form. We characterize the assembly and aging of this PG-ring and link its synthesis to MreB, an actin-like protein associated with lateral cell wall synthesis in bacteria. As PG is recognized by the host innate immune system, we hypothesize that the limited amount of PG synthesized by Chlamydia is an adaptation to the microbe’s intracellular lifestyle.
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Affiliation(s)
- George Liechti
- Department of Microbiology and Immunology, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland, United States of America
| | - Erkin Kuru
- Department of Chemistry, Indiana University, Bloomington, Indiana, United States of America
| | - Mathanraj Packiam
- Department of Microbiology and Immunology, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland, United States of America
| | - Yen-Pang Hsu
- Department of Chemistry, Indiana University, Bloomington, Indiana, United States of America
| | - Srinivas Tekkam
- Department of Chemistry, Indiana University, Bloomington, Indiana, United States of America
| | - Edward Hall
- Department of Chemistry, Indiana University, Bloomington, Indiana, United States of America
| | - Jonathan T Rittichier
- Department of Chemistry, Indiana University, Bloomington, Indiana, United States of America
| | - Michael VanNieuwenhze
- Department of Chemistry, Indiana University, Bloomington, Indiana, United States of America
| | - Yves V Brun
- Department of Biology, Indiana University, Bloomington, Indiana, United States of America
| | - Anthony T Maurelli
- Department of Microbiology and Immunology, F. Edward Hébert School of Medicine, Uniformed Services University of the Health Sciences, Bethesda, Maryland, United States of America
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Hamonic G, Pasternak JA, Käser T, Meurens F, Wilson HL. Extended semen for artificial insemination in swine as a potential transmission mechanism for infectious Chlamydia suis. Theriogenology 2016; 86:949-956. [PMID: 27087534 DOI: 10.1016/j.theriogenology.2016.03.018] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2015] [Revised: 03/10/2016] [Accepted: 03/12/2016] [Indexed: 10/22/2022]
Abstract
Although typically unnoticed, Chlamydia infections in swine have been shown to be both widespread and may impact production characteristics and reproductive performance in swine. Serum titers suggest Chlamydia infection within boar studs is common, and infected boars are known to shed chlamydia in their ejaculates. Although the transmission of viruses in chilled extended semen (ES) is well established, the inclusion of antibiotics in commercially available extender is generally believed to limit or preclude the transmission of infectious bacteria. The objective of this study was to evaluate the potential of ES used in artificial insemination to support transmission of the obligate intracellular bacteria Chlamydia suis (C suis) under standard industry conditions. First, the effect of C suis on sperm quality during storage was assessed by flow cytometry. Only concentrations above 5 × 10(5) viable C suis/mL caused significant spermicidal effects which only became evident after 7 days of storage at 17 °C. No significant effect on acrosome reaction was observed using any chlamydial concentration. Next, an in vitro infection model of swine testicular fibroblast cells was established and used to evaluate the effect of chilled storage on C suis viability under variable conditions. Storage in Androhep ES reduced viability by 34.4% at a multiplicity of infection of 1.25, an effect which increased to 53.3% when the multiplicity of infection decreased to 0.1. Interestingly, storage in semen extender alone (SE) or ES with additional antibiotics had no effect on bacterial viability. To rule out a secondary effect on extender resulting from metabolically active sperm, C suis was stored in fresh and expended SE and again no significant effect on bacterial viability was observed. Fluorescent microscopy of C suis in ES shows an association between bacteria and the remaining gel fraction after storage suggesting that the apparent reduction of bacterial viability in the presence of semen is due to adherence to gel fraction. Taken together, the results of this study suggest that C suis remains viable and infectious during chilled storage and is globally unaffected by antibiotics in extender. Thus, ES used in artificial insemination may act as a viable transmission mechanism for C suis in swine.
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Affiliation(s)
- G Hamonic
- Vaccine and Infectious Disease Organization (VIDO)-International Vaccine Centre (InterVac), University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - J A Pasternak
- Vaccine and Infectious Disease Organization (VIDO)-International Vaccine Centre (InterVac), University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - T Käser
- Vaccine and Infectious Disease Organization (VIDO)-International Vaccine Centre (InterVac), University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - F Meurens
- LUNAM Université, Oniris, Nantes-Atlantic College of Veterinary Medicine and Food Sciences and Engineering, UMR BioEpAR, Nantes, France; INRA, UMR1300 Biology, Epidemiology and Risk Analysis in Animal Health, Nantes, France
| | - H L Wilson
- Vaccine and Infectious Disease Organization (VIDO)-International Vaccine Centre (InterVac), University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
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Hai J, Serradji N, Mouton L, Redeker V, Cornu D, El Hage Chahine JM, Verbeke P, Hémadi M. Targeted Delivery of Amoxicillin to C. trachomatis by the Transferrin Iron Acquisition Pathway. PLoS One 2016; 11:e0150031. [PMID: 26919720 PMCID: PMC4768884 DOI: 10.1371/journal.pone.0150031] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Accepted: 02/08/2016] [Indexed: 01/13/2023] Open
Abstract
Weak intracellular penetration of antibiotics makes some infections difficult to treat. The Trojan horse strategy for targeted drug delivery is among the interesting routes being explored to overcome this therapeutic difficulty. Chlamydia trachomatis, as an obligate intracellular human pathogen, is responsible for both trachoma and sexually transmitted diseases. Chlamydia develops in a vacuole and is therefore protected by four membranes (plasma membrane, bacterial inclusion membrane, and bacterial membranes). In this work, the iron-transport protein, human serum-transferrin, was used as a Trojan horse for antibiotic delivery into the bacterial vacuole. Amoxicillin was grafted onto transferrin. The transferrin-amoxicillin construct was characterized by mass spectrometry and absorption spectroscopy. Its affinity for transferrin receptor 1, determined by fluorescence emission titration [KaffTf-amox = (1.3 ± 1.0) x 108], is very close to that of transferrin [4.3 x 108]. Transmission electron and confocal microscopies showed a co-localization of transferrin with the bacteria in the vacuole and were also used to evaluate the antibiotic capability of the construct. It is significantly more effective than amoxicillin alone. These promising results demonstrate targeted delivery of amoxicillin to suppress Chlamydia and are of interest for Chlamydiaceae and maybe other intracellular bacteria therapies.
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Affiliation(s)
- Jun Hai
- ITODYS, Interfaces, Traitements, Organisation et Dynamique des Systèmes, Université Paris Diderot, Sorbonne Paris Cité, CNRS-UMR 7086, 15 rue Jean-Antoine de Baïf, 75205 Paris Cedex 13, France
| | - Nawal Serradji
- ITODYS, Interfaces, Traitements, Organisation et Dynamique des Systèmes, Université Paris Diderot, Sorbonne Paris Cité, CNRS-UMR 7086, 15 rue Jean-Antoine de Baïf, 75205 Paris Cedex 13, France
| | - Ludovic Mouton
- ITODYS, Interfaces, Traitements, Organisation et Dynamique des Systèmes, Université Paris Diderot, Sorbonne Paris Cité, CNRS-UMR 7086, 15 rue Jean-Antoine de Baïf, 75205 Paris Cedex 13, France
| | - Virginie Redeker
- Paris-Saclay Institute of Neuroscience, CNRS-UMR 9197, 1 avenue de la Terrasse, 91190 Gif-sur-Yvette, France
| | - David Cornu
- Service d’Identification et de Caractérisation des Protéines, CNRS-UMR 9198, 1 avenue de la Terrasse, 91190 Gif-sur-Yvette, France
| | - Jean-Michel El Hage Chahine
- ITODYS, Interfaces, Traitements, Organisation et Dynamique des Systèmes, Université Paris Diderot, Sorbonne Paris Cité, CNRS-UMR 7086, 15 rue Jean-Antoine de Baïf, 75205 Paris Cedex 13, France
- * E-mail: (MH); (JEHC); (PV)
| | - Philippe Verbeke
- UMR 1149 Inserm, Université Paris Diderot, Sorbonne Paris Cité, ERL-CNRS 8252, Faculté de Médecine, site Bichat, 16 rue Henri Huchard, 75018 Paris, France
- * E-mail: (MH); (JEHC); (PV)
| | - Miryana Hémadi
- ITODYS, Interfaces, Traitements, Organisation et Dynamique des Systèmes, Université Paris Diderot, Sorbonne Paris Cité, CNRS-UMR 7086, 15 rue Jean-Antoine de Baïf, 75205 Paris Cedex 13, France
- * E-mail: (MH); (JEHC); (PV)
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Penicillin G-Induced Chlamydial Stress Response in a Porcine Strain of Chlamydia pecorum. Int J Microbiol 2016; 2016:3832917. [PMID: 26997956 PMCID: PMC4779511 DOI: 10.1155/2016/3832917] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Accepted: 01/26/2016] [Indexed: 01/14/2023] Open
Abstract
Chlamydia pecorum causes asymptomatic infection and pathology in ruminants, pigs, and koalas. We characterized the antichlamydial effect of the beta lactam penicillin G on Chlamydia pecorum strain 1710S (porcine abortion isolate). Penicillin-exposed and mock-exposed infected host cells showed equivalent inclusions numbers. Penicillin-exposed inclusions contained aberrant bacterial forms and exhibited reduced infectivity, while mock-exposed inclusions contained normal bacterial forms and exhibited robust infectivity. Infectious bacteria production increased upon discontinuation of penicillin exposure, compared to continued exposure. Chlamydia-induced cell death occurred in mock-exposed controls; cell survival was improved in penicillin-exposed infected groups. Similar results were obtained both in the presence and in the absence of the eukaryotic protein translation inhibitor cycloheximide and at different times of initiation of penicillin exposure. These data demonstrate that penicillin G induces the chlamydial stress response (persistence) and is not bactericidal, for this chlamydial species/strain in vitro, regardless of host cell de novo protein synthesis.
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Abdelsayed S, Ha Duong N, Hai J, Hémadi M, El Hage Chahine J, Verbeke P, Serradji N. Design and synthesis of 3-isoxazolidone derivatives as new Chlamydia trachomatis inhibitors. Bioorg Med Chem Lett 2014; 24:3854-60. [DOI: 10.1016/j.bmcl.2014.06.056] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Revised: 06/17/2014] [Accepted: 06/19/2014] [Indexed: 12/19/2022]
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Golgi fragmentation and sphingomyelin transport to Chlamydia trachomatis during penicillin-induced persistence do not depend on the cytosolic presence of the chlamydial protease CPAF. PLoS One 2014; 9:e103220. [PMID: 25068694 PMCID: PMC4113379 DOI: 10.1371/journal.pone.0103220] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Accepted: 06/30/2014] [Indexed: 11/24/2022] Open
Abstract
Chlamydia grows inside a cytosolic vacuole (the inclusion) that is supplied with nutrients by the host through vesicular and non-vesicular transport. It is unclear in many respects how Chlamydia organizes this transport. One model posits that the Chlamydia-induced fragmentation of the Golgi-apparatus is required for normal transport processes to the inclusion and for chlamydial development, and the chlamydial protease CPAF has been controversially implicated in Golgi-fragmentation. We here use a model of penicillin-induced persistence of infection with Chlamydia trachomatis to test this link. Under penicillin-treatment the inclusion grew in size for the first 24 h but after that growth was severely reduced. Penicillin did not reduce the number of infected cells with fragmented Golgi-apparatus, and normal Golgi-fragmentation was found in a CPAF-deficient mutant. Surprisingly, sphingomyelin transport into the inclusion and into the bacteria, as measured by fluorescence accumulation upon addition of labelled ceramide, was not reduced during penicillin-treatment. Thus, both Golgi-fragmentation and transport of sphingomyelin to C. trachomatis still occurred in this model of persistence. The portion of cells in which CPAF was detected in the cytosol, either by immunofluorescence or by immune-electron microscopy, was drastically reduced in cells cultured in the presence of penicillin. These data argue against an essential role of cytosolic CPAF for Golgi-fragmentation or for sphingomyelin transport in chlamydial infection.
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