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Wurihan W, Wang Y, Yeung S, Zou Y, Lai Z, Fondell JD, Li WV, Zhong G, Fan H. Expression activation of over 70% of Chlamydia trachomatis genes during the first hour of infection. Infect Immun 2024; 92:e0053923. [PMID: 38299827 PMCID: PMC10929459 DOI: 10.1128/iai.00539-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2024] [Accepted: 01/09/2024] [Indexed: 02/02/2024] Open
Abstract
The obligate intracellular bacterium Chlamydia has a unique developmental cycle that alternates between two contrasting cell types. With a hardy envelope and highly condensed genome, the small elementary body (EB) maintains limited metabolic activities yet survives in extracellular environments and is infectious. After entering host cells, EBs differentiate into larger and proliferating reticulate bodies (RBs). Progeny EBs are derived from RBs in late developmental stages and eventually exit host cells. How expression of the chlamydial genome consisting of nearly 1,000 genes governs the chlamydial developmental cycle is unclear. A previous microarray study identified only 29 Chlamydia trachomatis immediate early genes, defined as genes with increased expression during the first hour postinoculation in cultured cells. In this study, we performed more sensitive RNA sequencing (RNA-Seq) analysis for C. trachomatis cultures with high multiplicities of infection. Remarkably, we observed well over 700 C. trachomatis genes that underwent 2- to 900-fold activation within 1 hour postinoculation. Quantitative reverse transcription real-time PCR analysis was further used to validate the activated expression of a large subset of the genes identified by RNA-Seq. Importantly, our results demonstrate that the immediate early transcriptome is over 20 times more extensive than previously realized. Gene ontology analysis indicates that the activated expression spans all functional categories. We conclude that over 70% of C. trachomatis genes are activated in EBs almost immediately upon entry into host cells, thus implicating their importance in initiating rapid differentiation into RBs and establishing an intracellular niche conducive with chlamydial development and growth.
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Affiliation(s)
- Wurihan Wurihan
- Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA
- Institute of Translational Medicine, Medical College, Yangzhou University, Yangzhou, China
| | - Yuxuan Wang
- Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA
| | - Sydney Yeung
- Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA
| | - Yi Zou
- Greehey Children's Cancer Research Institute, University of Texas Health San Antonio, San Antonio, Texas, USA
| | - Zhao Lai
- Greehey Children's Cancer Research Institute, University of Texas Health San Antonio, San Antonio, Texas, USA
- Department of Molecular Medicine, University of Texas Health San Antonio, San Antonio, Texas, USA
| | - Joseph D. Fondell
- Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA
| | - Wei Vivian Li
- Department of Statistics, University of California Riverside, Riverside, California, USA
| | - Guangming Zhong
- Department of Microbiology and Immunology, University of Texas Health San Antonio, San Antonio, Texas, USA
| | - Huizhou Fan
- Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA
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2
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Lu B, Wang Y, Wurihan W, Cheng A, Yeung S, Fondell JD, Lai Z, Wan D, Wu X, Li WV, Fan H. Requirement of GrgA for Chlamydia infectious progeny production, optimal growth, and efficient plasmid maintenance. mBio 2024; 15:e0203623. [PMID: 38112466 PMCID: PMC10790707 DOI: 10.1128/mbio.02036-23] [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: 08/01/2023] [Accepted: 11/16/2023] [Indexed: 12/21/2023] Open
Abstract
IMPORTANCE Hallmarks of the developmental cycle of the obligate intracellular pathogenic bacterium Chlamydia are the primary differentiation of the infectious elementary body (EB) into the proliferative reticulate body (RB) and the secondary differentiation of RBs back into EBs. The mechanisms regulating these transitions remain unclear. In this report, we developed an effective novel strategy termed dependence on plasmid-mediated expression (DOPE) that allows for the knockdown of essential genes in Chlamydia. We demonstrate that GrgA, a Chlamydia-specific transcription factor, is essential for the secondary differentiation and optimal growth of RBs. We also show that GrgA, a chromosome-encoded regulatory protein, controls the maintenance of the chlamydial virulence plasmid. Transcriptomic analysis further indicates that GrgA functions as a critical regulator of all three sigma factors that recognize different promoter sets at developmental stages. The DOPE strategy outlined here should provide a valuable tool for future studies examining chlamydial growth, development, and pathogenicity.
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Affiliation(s)
- Bin Lu
- Department of Parasitology, Central South University Xiangya Medical School, Changsha, Hunan, China
- Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA
| | - Yuxuan Wang
- Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA
| | - Wurihan Wurihan
- Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA
| | - Andrew Cheng
- Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA
| | - Sydney Yeung
- Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA
| | - Joseph D. Fondell
- Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA
| | - Zhao Lai
- Greehey Children's Cancer Research Institute, University of Texas Health San Antonio, San Antonio, Texas, USA
- Department of Molecular Medicine, University of Texas Health San Antonio, San Antonio, Texas, USA
| | - Danny Wan
- Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA
| | - Xiang Wu
- Department of Parasitology, Central South University Xiangya Medical School, Changsha, Hunan, China
| | - Wei Vivian Li
- Department of Statistics, University of California Riverside, Riverside, California, USA
| | - Huizhou Fan
- Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, New Jersey, USA
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3
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Hakiem OR, Rizvi SMA, Ramirez C, Tan M. Euo is a developmental regulator that represses late genes and activates midcycle genes in Chlamydia trachomatis. mBio 2023; 14:e0046523. [PMID: 37565751 PMCID: PMC10653925 DOI: 10.1128/mbio.00465-23] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2023] [Accepted: 05/22/2023] [Indexed: 08/12/2023] Open
Abstract
IMPORTANCE In this study, we developed a correlative approach that combined DNA immunoprecipitation-seq and RNA-seq analyses to define the regulon of the Chlamydia trachomatis transcription factor Euo. We confirmed the proposed role of Euo as a transcriptional repressor of late chlamydial genes but also showed that Euo activates transcription of a subset of midcycle genes and autoregulates its own expression via negative feedback. This study validates and expands the role of Euo as an important developmental regulator in C. trachomatis. In addition, this genome-wide correlative approach can be applied to study transcription factors in other pathogenic bacteria.
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Affiliation(s)
- Owais R. Hakiem
- Department of Microbiology and Molecular Genetics, University of California Irvine, Irvine, California, USA
| | - Syed M. A. Rizvi
- Department of Microbiology and Molecular Genetics, University of California Irvine, Irvine, California, USA
| | - Cuper Ramirez
- Department of Developmental and Cell Biology, University of California Irvine, Irvine, California, USA
| | - Ming Tan
- Department of Microbiology and Molecular Genetics, University of California Irvine, Irvine, California, USA
- Department of Medicine, University of California Irvine, Irvine, California, USA
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4
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Lu B, Wang Y, Wurihan W, Cheng A, Yeung S, Fondell JD, Lai Z, Wan D, Wu X, Li WV, Fan H. Requirement of GrgA for Chlamydia infectious progeny production, optimal growth, and efficient plasmid maintenance. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.02.551707. [PMID: 37577610 PMCID: PMC10418237 DOI: 10.1101/2023.08.02.551707] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/15/2023]
Abstract
Chlamydia, an obligate intracellular bacterial pathogen, has a unique developmental cycle involving the differentiation of invading elementary bodies (EBs) to noninfectious reticulate bodies (RBs), replication of RBs, and redifferentiation of RBs into progeny EBs. Progression of this cycle is regulated by three sigma factors, which direct the RNA polymerase to their respective target gene promoters. We hypothesized that the Chlamydia-specific transcriptional regulator GrgA, previously shown to activate σ66 and σ28, plays an essential role in chlamydial development and growth. To test this hypothesis, we applied a novel genetic tool known as dependence on plasmid-mediated expression (DOPE) to create Chlamydia trachomatis with conditional GrgA-deficiency. We show that GrgA-deficient C. trachomatis RBs have a growth rate that is approximately half of the normal rate and fail to transition into progeny EBs. In addition, GrgA-deficient C. trachomatis fail to maintain its virulence plasmid. Results of RNA-seq analysis indicate that GrgA promotes RB growth by optimizing tRNA synthesis and expression of nutrient-acquisition genes, while it enables RB-to-EB conversion by facilitating the expression of a histone and outer membrane proteins required for EB morphogenesis. GrgA also regulates numerous other late genes required for host cell exit and subsequent EB invasion into host cells. Importantly, GrgA stimulates the expression of σ54, the third and last sigma factor, and its activator AtoC, and thereby indirectly upregulating the expression of σ54-dependent genes. In conclusion, our work demonstrates that GrgA is a master transcriptional regulator in Chlamydia and plays multiple essential roles in chlamydial pathogenicity.
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Affiliation(s)
- Bin Lu
- Department of Parasitology, Central South University Xiangya Medical School, Changsha, Hunan 410013, China
- Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Yuxuan Wang
- Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Wurihan Wurihan
- Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Andrew Cheng
- Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Sydney Yeung
- Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Joseph D. Fondell
- Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Zhao Lai
- Greehey Children's Cancer Research Institute, University of Texas Health San Antonio, San Antonio, TX 78229, USA
- Department of Molecular Medicine, University of Texas Health San Antonio, San Antonio, TX 78229, USA
| | - Danny Wan
- Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
| | - Xiang Wu
- Department of Parasitology, Central South University Xiangya Medical School, Changsha, Hunan 410013, China
| | - Wei Vivian Li
- Department of Statistics, University of California Riverside, Riverside, CA 92521, USA
| | - Huizhou Fan
- Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
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5
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Dharamshi JE, Köstlbacher S, Schön ME, Collingro A, Ettema TJG, Horn M. Gene gain facilitated endosymbiotic evolution of Chlamydiae. Nat Microbiol 2023; 8:40-54. [PMID: 36604515 PMCID: PMC9816063 DOI: 10.1038/s41564-022-01284-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Accepted: 11/07/2022] [Indexed: 01/07/2023]
Abstract
Chlamydiae is a bacterial phylum composed of obligate animal and protist endosymbionts. However, other members of the Planctomycetes-Verrucomicrobia-Chlamydiae superphylum are primarily free living. How Chlamydiae transitioned to an endosymbiotic lifestyle is still largely unresolved. Here we reconstructed Planctomycetes-Verrucomicrobia-Chlamydiae species relationships and modelled superphylum genome evolution. Gene content reconstruction from 11,996 gene families suggests a motile and facultatively anaerobic last common Chlamydiae ancestor that had already gained characteristic endosymbiont genes. Counter to expectations for genome streamlining in strict endosymbionts, we detected substantial gene gain within Chlamydiae. We found that divergence in energy metabolism and aerobiosis observed in extant lineages emerged later during chlamydial evolution. In particular, metabolic and aerobic genes characteristic of the more metabolically versatile protist-infecting chlamydiae were gained, such as respiratory chain complexes. Our results show that metabolic complexity can increase during endosymbiont evolution, adding an additional perspective for understanding symbiont evolutionary trajectories across the tree of life.
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Affiliation(s)
- Jennah E Dharamshi
- Department of Cell and Molecular Biology, Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Stephan Köstlbacher
- University of Vienna, Centre for Microbiology and Environmental Systems Science, Vienna, Austria
- University of Vienna, Doctoral School in Microbiology and Environmental Science, Vienna, Austria
- Laboratory of Microbiology, Wageningen University and Research, Wageningen, The Netherlands
| | - Max E Schön
- Department of Cell and Molecular Biology, Science for Life Laboratory, Uppsala University, Uppsala, Sweden
| | - Astrid Collingro
- University of Vienna, Centre for Microbiology and Environmental Systems Science, Vienna, Austria
| | - Thijs J G Ettema
- Department of Cell and Molecular Biology, Science for Life Laboratory, Uppsala University, Uppsala, Sweden.
- Laboratory of Microbiology, Wageningen University and Research, Wageningen, The Netherlands.
| | - Matthias Horn
- University of Vienna, Centre for Microbiology and Environmental Systems Science, Vienna, Austria.
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6
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Rosario C, Tan M. Chlamydia trachomatis RsbU Phosphatase Activity Is Inhibited by the Enolase Product, Phosphoenolpyruvate. J Bacteriol 2022; 204:e0017822. [PMID: 36121291 PMCID: PMC9578391 DOI: 10.1128/jb.00178-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Accepted: 08/22/2022] [Indexed: 11/20/2022] Open
Abstract
The intracellular pathogen Chlamydia temporally regulates the expression of its genes, but the upstream signals that control transcription are not known. The best-studied regulatory pathway is a partner-switching mechanism that involves an anti-sigma factor, RsbW, which inhibits transcription by binding and sequestering the sigma subunit of RNA polymerase. RsbW is itself regulated by an anti-anti-sigma factor, RsbV, whose phosphorylation state is controlled by the phosphatase RsbU. In this study, we showed that Chlamydia trachomatis RsbU requires manganese or magnesium as a cofactor and dephosphorylates RsbV1 and RsbV2, which are the two chlamydial paralogs of RsbV. The gene for RsbU is adjacent to the enolase gene in a number of Chlamydia genomes, and we showed that eno and rsbU are cotranscribed from the same operon. In other bacteria, there is no known functional connection between the Rsb pathway and enolase, which is an enzyme in the glycolytic pathway. We found, however, that Chlamydia RsbU phosphatase activity was inhibited by phosphoenolpyruvate (PEP), the product of the enolase reaction, but not by 2-phosphoglycerate (2PGA), which is the substrate. These findings suggest that the enolase reaction and, more generally, glucose metabolism, may provide an upstream signal that regulates transcription in Chlamydia through the RsbW pathway. IMPORTANCE The RsbW pathway is a phosphorelay that regulates gene expression in Chlamydia, but its upstream signal has not been identified. We showed that RsbU, a phosphatase in this pathway, is inhibited by phosphoenolpyruvate, which is the product of the enolase reaction. As enolase is an enzyme in the glycolytic pathway, these results reveal an unrecognized link between glucose metabolism and gene regulation in chlamydiae. Moreover, as these intracellular bacteria acquire glucose from the infected host cell, our findings suggest that glucose availability may be an external signal that controls chlamydial gene expression.
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Affiliation(s)
- Christopher Rosario
- Department of Microbiology and Molecular Genetics, University of California, Irvine, California, USA
| | - Ming Tan
- Department of Microbiology and Molecular Genetics, University of California, Irvine, California, USA
- Department of Medicine, University of California, Irvine, California, USA
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7
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Huston WM, Lawrence A, Wee BA, Thomas M, Timms P, Vodstrcil LA, McNulty A, McIvor R, Worthington K, Donovan B, Phillips S, Chen MY, Fairley CK, Hocking JS. Repeat infections with chlamydia in women may be more transcriptionally active with lower responses from some immune genes. Front Public Health 2022; 10:1012835. [PMID: 36299763 PMCID: PMC9589431 DOI: 10.3389/fpubh.2022.1012835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Accepted: 09/23/2022] [Indexed: 01/27/2023] Open
Abstract
Chlamydia trachomatis, the most common bacterial sexually transmitted infection worldwide, is responsible for considerable health burden due to its significant sequelae. There are growing concerns about chlamydial treatment and management due to widely documented increasing burden of repeat infections. In the current study, a cohort study design of 305 women with urogenital chlamydial infections demonstrated that 11.8% of women experienced repeat infections after treatment with azithromycin. The chlamydial DNA load measured by quantitative PCR was higher in women who experienced a repeat infection (p = 0.0097) and repeat infection was associated with sexual contact. There was no genomic or phenotypic evidence of azithromycin resistance within the chlamydial isolates. During repeat infection, or repeat positive tests during follow up, vaginal chlamydial gene expression (ompA, euo, omcB, htrA, trpAB) was markedly higher compared to baseline, and two of the selected immune genes analyzed had significantly lower expression at the time of repeat infection. Overall, there are two implications of these results. The results could be generalized to all recent infections, or repeat positive events, and indicate that chlamydial infections are have higher transcriptional activity of select genes early in the infection in women. Alternatively, after azithromycin treatment, repeat infections of Chlamydia may be more transcriptionally active at certain genes, and there may be post-treatment immunological alterations that interplay into repeat exposures establishing an active infection. The potential that recent infections may involve a higher level of activity from the organism may have implications for management by more regular testing of the most at risk women to reduce the risk of sequelae.
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Affiliation(s)
- Wilhelmina M. Huston
- Faculty of Science, University of Technology Sydney, Ultimo, NSW, Australia,*Correspondence: Wilhelmina M. Huston
| | - Amba Lawrence
- Institute of Health and Biomedical Innovation, Queensland University of Technology, Kelvin Grove, QLD, Australia
| | - Bryan A. Wee
- Institute of Health and Biomedical Innovation, Queensland University of Technology, Kelvin Grove, QLD, Australia
| | - Mark Thomas
- Faculty of Science, University of Technology Sydney, Ultimo, NSW, Australia
| | - Peter Timms
- Bioinnovation Centre, University of the Sunshine Coast, Sippy Downs, QLD, Australia
| | - Lenka A. Vodstrcil
- Melbourne Sexual Health Centre, Central Clinical School, Monash University, Carlton, VIC, Australia,Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne, Carlton, VIC, Australia
| | - Anna McNulty
- Sydney Sexual Health Centre, Sydney, NSW, Australia
| | - Ruthy McIvor
- Sydney Sexual Health Centre, Sydney, NSW, Australia
| | - Karen Worthington
- Melbourne Sexual Health Centre, Alfred Health, Carlton, VIC, Australia
| | - Basil Donovan
- Kirby Institute, University of New South Wales, Kensington, NSW, Australia
| | - Samuel Phillips
- Bioinnovation Centre, University of the Sunshine Coast, Sippy Downs, QLD, Australia
| | - Marcus Y. Chen
- Melbourne School of Population and Global Health, University of Melbourne, Carlton, VIC, Australia,Australia and Melbourne Sexual Health Centre, Carlton, VIC, Australia
| | | | - Jane S. Hocking
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne, Carlton, VIC, Australia,Jane S. Hocking
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8
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Huang Y, Wurihan W, Lu B, Zou Y, Wang Y, Weldon K, Fondell JD, Lai Z, Wu X, Fan H. Robust Heat Shock Response in Chlamydia Lacking a Typical Heat Shock Sigma Factor. Front Microbiol 2022; 12:812448. [PMID: 35046926 PMCID: PMC8762339 DOI: 10.3389/fmicb.2021.812448] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2021] [Accepted: 12/02/2021] [Indexed: 11/13/2022] Open
Abstract
Cells reprogram their transcriptome in response to stress, such as heat shock. In free-living bacteria, the transcriptomic reprogramming is mediated by increased DNA-binding activity of heat shock sigma factors and activation of genes normally repressed by heat-induced transcription factors. In this study, we performed transcriptomic analyses to investigate heat shock response in the obligate intracellular bacterium Chlamydia trachomatis, whose genome encodes only three sigma factors and a single heat-induced transcription factor. Nearly one-third of C. trachomatis genes showed statistically significant (≥1.5-fold) expression changes 30 min after shifting from 37 to 45°C. Notably, chromosomal genes encoding chaperones, energy metabolism enzymes, type III secretion proteins, as well as most plasmid-encoded genes, were differentially upregulated. In contrast, genes with functions in protein synthesis were disproportionately downregulated. These findings suggest that facilitating protein folding, increasing energy production, manipulating host activities, upregulating plasmid-encoded gene expression, and decreasing general protein synthesis helps facilitate C. trachomatis survival under stress. In addition to relieving negative regulation by the heat-inducible transcriptional repressor HrcA, heat shock upregulated the chlamydial primary sigma factor σ66 and an alternative sigma factor σ28. Interestingly, we show for the first time that heat shock downregulates the other alternative sigma factor σ54 in a bacterium. Downregulation of σ54 was accompanied by increased expression of the σ54 RNA polymerase activator AtoC, thus suggesting a unique regulatory mechanism for reestablishing normal expression of select σ54 target genes. Taken together, our findings reveal that C. trachomatis utilizes multiple novel survival strategies to cope with environmental stress and even to replicate. Future strategies that can specifically target and disrupt Chlamydia’s heat shock response will likely be of therapeutic value.
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Affiliation(s)
- Yehong Huang
- Department of Parasitology, Xiangya School of Basic Medicine, Central South University, Changsha, China.,Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ, United States
| | - Wurihan Wurihan
- Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ, United States
| | - Bin Lu
- Department of Parasitology, Xiangya School of Basic Medicine, Central South University, Changsha, China.,Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ, United States
| | - Yi Zou
- Greehey Children's Cancer Research Institute, University of Texas Health San Antonio, San Antonio, TX, United States
| | - Yuxuan Wang
- Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ, United States
| | - Korri Weldon
- Greehey Children's Cancer Research Institute, University of Texas Health San Antonio, San Antonio, TX, United States
| | - Joseph D Fondell
- Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ, United States
| | - Zhao Lai
- Greehey Children's Cancer Research Institute, University of Texas Health San Antonio, San Antonio, TX, United States.,Department of Molecular Medicine, University of Texas Health San Antonio, San Antonio, TX, United States
| | - Xiang Wu
- Department of Parasitology, Xiangya School of Basic Medicine, Central South University, Changsha, China
| | - Huizhou Fan
- Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ, United States
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9
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Abstract
Chlamydia trachomatis is an obligate intracellular bacterium whose unique developmental cycle consists of an infectious elementary body and a replicative reticulate body. Progression of this developmental cycle requires temporal control of the transcriptome. In addition to the three chlamydial sigma factors (σ66, σ28, and σ54) that recognize promoter sequences of genes, chlamydial transcription factors are expected to play crucial roles in transcriptional regulation. Here, we investigate the function of GrgA, a Chlamydia-specific transcription factor, in C. trachomatis transcriptomic expression. We show that 10 to 30 min of GrgA overexpression induces 13 genes, which likely comprise the direct regulon of GrgA. Significantly, σ66-dependent genes that code for two important transcription repressors are components of the direct regulon. One of these repressors is Euo, which prevents the expression of late genes during early phases. The other is HrcA, which regulates molecular chaperone expression and controls stress response. The direct regulon also includes a σ28-dependent gene that codes for the putative virulence factor PmpI. Furthermore, overexpression of GrgA leads to decreased expression of almost all tRNAs. Transcriptomic studies suggest that GrgA, Euo, and HrcA have distinct but overlapping indirect regulons. These findings, together with temporal expression patterns of grgA, euo, and hrcA, indicate that a transcriptional regulatory network of these three transcription factors plays critical roles in C. trachomatis growth and development. IMPORTANCEChlamydia trachomatis is the most prevalent sexually transmitted bacterial pathogen worldwide and is a leading cause of preventable blindness in underdeveloped areas as well as some developed countries. Chlamydia carries genes that encode a limited number of known transcription factors. While Euo is thought to be critical for early chlamydial development, the functions of GrgA and HrcA in the developmental cycle are unclear. Activation of euo and hrcA immediately following GrgA overexpression indicates that GrgA functions as a master transcriptional regulator. In addition, by broadly inhibiting tRNA expression, GrgA serves as a key regulator of chlamydial protein synthesis. Furthermore, by upregulating pmpI, GrgA may act as an upstream virulence determinant. Finally, genes coregulated by GrgA, Euo, and HrcA likely play critical roles in chlamydial growth and developmental control.
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10
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Wurihan W, Weber AM, Gong Z, Lou Z, Sun S, Zhou J, Fan H. GrgA overexpression inhibits Chlamydia trachomatis growth through sigma 66- and sigma 28-dependent mechanisms. Microb Pathog 2021; 156:104917. [PMID: 33940135 PMCID: PMC8187326 DOI: 10.1016/j.micpath.2021.104917] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Revised: 04/01/2021] [Accepted: 04/02/2021] [Indexed: 01/21/2023]
Abstract
The obligate intracellular bacterium Chlamydia trachomatis is an important human pathogen with a biphasic developmental cycle comprised of an infectious elementary body (EB) and a replicative reticulate body (RB). Whereas σ66, the primary sigma factor, is necessary for transcription of most chlamydial genes throughout the developmental cycle, σ28 is required for expression of some late genes. We previously showed that the Chlamydia-specific transcription factor GrgA physically interacts with both of these sigma factors and activates transcription from σ66- and σ28-dependent promoters in vitro. Here, we investigated the organismal functions of GrgA. We show that overexpression of GrgA slows EB-to-RB conversion, decreases RB proliferation, and reduces progeny EB production. In contrast, overexpression of a GrgA variant without the σ28-binding domain shows significantly less severe inhibitory effects, while overexpression of a variant without the σ66-binding domain demonstrates no adverse effects. These findings indicate that GrgA plays important roles in the expression regulation of both σ66-dependent genes and σ28-dependent genes during the chlamydial developmental cycle.
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Affiliation(s)
- Wurihan Wurihan
- Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers The State University of New Jersey, Piscataway, NJ, 08854, USA
| | - Alec M Weber
- Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers The State University of New Jersey, Piscataway, NJ, 08854, USA
| | - Zheng Gong
- Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers The State University of New Jersey, Piscataway, NJ, 08854, USA
| | - Zhongzi Lou
- Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers The State University of New Jersey, Piscataway, NJ, 08854, USA; Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, 730046, China
| | - Samantha Sun
- Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers The State University of New Jersey, Piscataway, NJ, 08854, USA
| | - Jizhang Zhou
- Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, 730046, China
| | - Huizhou Fan
- Department of Pharmacology, Robert Wood Johnson Medical School, Rutgers The State University of New Jersey, Piscataway, NJ, 08854, USA.
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11
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Chen Y, Wang C, Mi J, Zhou Z, Wang J, Tang M, Yu J, Liu A, Wu Y. Characterization and comparison of differentially expressed genes involved in Chlamydia psittaci persistent infection in vitro and in vivo. Vet Microbiol 2021; 255:108960. [PMID: 33667981 DOI: 10.1016/j.vetmic.2020.108960] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2020] [Accepted: 12/12/2020] [Indexed: 10/22/2022]
Abstract
Chlamydia psittaci is an obligate intracellular zoonotic pathogen that can enter a persistence state in host cells. While the exact pathogenesis is not well understood, this persistence state may play an important role in chronic Chlamydia disease. Here, we assess the effects of chlamydial persistence state in vitro and in vivo by transmission electron microscopy (TEM) and cDNA microarray assays. First, IFN-γ-induced C. psittaci persistence in HeLa cells resulted in the upregulation of 68 genes. These genes are involved in protein translation, carbohydrate metabolism, nucleotide metabolism, lipid metabolism and general stress. However, 109 genes were downregulated following persistent C. psittaci infection, many of which are involved in the TCA cycle, expression regulation and transcription, protein secretion, proteolysis and transport, membrane protein, presumed virulence factor, cell division and late expression. To further study differential gene expression of C. psittaci persistence in vivo, we established an experimentally tractable mouse model of C. psittaci persistence. The C. psittaci-infected mice were gavaged with either water or amoxicillin (amox), and the results indicated that the 20 mg/kg amox-exposed C. psittaci were viable but not infectious. Differentially expressed genes (DEGs) screened by cDNA microarray were detected, and interestingly, the results showed upregulation of three genes (euo, ahpC, prmC) and downregulation of five genes (pbp3, sucB_1, oppA_4, pmpH, ligA) in 20 mg/kg amox-exposed C. psittaci, which suggests that antibiotic treatment in vivo can induce chlamydial persistence state and lead to differential gene expression. However, the discrepancy on inducers between the two models requires more research to supplement. The results may help researchers better understand survival advantages during persistent infection and mechanisms influencing C. psittaci pathogenesis or evasion of the adaptive immune response.
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Affiliation(s)
- Yuqing Chen
- Institute of Pathogenic Biology, Hengyang Medical College, University of South China, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, University of South China, Hunan Provincial Key Laboratory for Special Pathogens Prevention and Control, University of South China, Hengyang, Hunan, 421001, China; Clinical Microbiology Laboratory, Xiangtan Central Hospital, Xiangtan, 411100, China
| | - Chuan Wang
- Institute of Pathogenic Biology, Hengyang Medical College, University of South China, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, University of South China, Hunan Provincial Key Laboratory for Special Pathogens Prevention and Control, University of South China, Hengyang, Hunan, 421001, China
| | - Jing Mi
- Department of Hospital Infection and Control, The First Affiliated Hospital of University of South China, Hengyang, 421001, China
| | - Zhou Zhou
- Institute of Pathogenic Biology, Hengyang Medical College, University of South China, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, University of South China, Hunan Provincial Key Laboratory for Special Pathogens Prevention and Control, University of South China, Hengyang, Hunan, 421001, China
| | - Jianye Wang
- Institute of Pathogenic Biology, Hengyang Medical College, University of South China, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, University of South China, Hunan Provincial Key Laboratory for Special Pathogens Prevention and Control, University of South China, Hengyang, Hunan, 421001, China
| | - Manjuan Tang
- Clinical Microbiology Laboratory, Xiangtan Central Hospital, Xiangtan, 411100, China
| | - Jian Yu
- Department of Experimental Zoology, Hengyang Medical College, University of South China, Hengyang, 421001, China
| | - Anyuan Liu
- Clinical Medical Research Center, The Second Affiliated Hospital of University of South China, Hengyang, 421001, China.
| | - Yimou Wu
- Institute of Pathogenic Biology, Hengyang Medical College, University of South China, Hunan Province Cooperative Innovation Center for Molecular Target New Drug Study, University of South China, Hunan Provincial Key Laboratory for Special Pathogens Prevention and Control, University of South China, Hengyang, Hunan, 421001, China.
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12
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Marangoni A, Zalambani C, Marziali G, Salvo M, Fato R, Foschi C, Re MC. Low-dose doxycycline induces Chlamydia trachomatis persistence in HeLa cells. Microb Pathog 2020; 147:104347. [PMID: 32561420 DOI: 10.1016/j.micpath.2020.104347] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 05/04/2020] [Accepted: 06/11/2020] [Indexed: 02/03/2023]
Abstract
Chlamydia persistence is a viable but non-replicative stage, induced by several sub-lethal stressor agents, including beta-lactam antibiotics. So far, no data about the connection between doxycycline and chlamydial persistence has been described in literature. We investigated the ability of doxycycline to induce C. trachomatis (CT) persistence in an in vitro model of epithelial cell infection (HeLa cells), comparing the results with the well-established model of penicillin-induced persistence. The effect of doxycycline was explored on 10 different CT strains by analysing (i) the presence of aberrant inclusions, (ii) chlamydial recovery, (iii) the expression of different chlamydial genes (omcB, euo, Ct110, Ct604, Ct755, HtrA) and (iv) the effects on epithelial cell viability. For each strain, the presence of foreign genomic islands responsible of tetracycline resistance was excluded. We found that low doses of doxycycline can induce a condition of CT persistence. For concentrations of doxycycline equal to 0.03-0.015 mg/L, CT inclusions are smaller and aberrant and CT cycle is characterized by the presence of viable but non-dividing RBs with the complete abolishment of chlamydial cytotoxic effect. Infectious EBs can be recovered after removal of the drug. During doxycycline-induced persistence, the expression of the late gene omcB is decreased, indicating the blocking of RB-to-EB conversion. Conversely, as for penicillin G, a significant up-regulation of the stress response HtrA gene is found in doxycycline-treated cells. This study provides a novel in vitro cell model to examine the characteristics of doxycycline-induced persistent CT infection.
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Affiliation(s)
- Antonella Marangoni
- University of Bologna, Department of Experimental, Diagnostic and Specialty Medicine-DIMES, Microbiology Unit, Via Massarenti 9, Bologna, Italy
| | - Chiara Zalambani
- University of Bologna, Department of Experimental, Diagnostic and Specialty Medicine-DIMES, Microbiology Unit, Via Massarenti 9, Bologna, Italy
| | - Giacomo Marziali
- University of Bologna, FaBiT Department, Via Irnerio 48, Bologna, Italy
| | - Melissa Salvo
- University of Bologna, Department of Experimental, Diagnostic and Specialty Medicine-DIMES, Microbiology Unit, Via Massarenti 9, Bologna, Italy
| | - Romana Fato
- University of Bologna, FaBiT Department, Via Irnerio 48, Bologna, Italy
| | - Claudio Foschi
- University of Bologna, Department of Experimental, Diagnostic and Specialty Medicine-DIMES, Microbiology Unit, Via Massarenti 9, Bologna, Italy.
| | - Maria Carla Re
- University of Bologna, Department of Experimental, Diagnostic and Specialty Medicine-DIMES, Microbiology Unit, Via Massarenti 9, Bologna, Italy
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13
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The Repressor Function of the Chlamydia Late Regulator EUO Is Enhanced by the Plasmid-Encoded Protein Pgp4. J Bacteriol 2020; 202:JB.00793-19. [PMID: 31988079 DOI: 10.1128/jb.00793-19] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 01/13/2020] [Indexed: 11/20/2022] Open
Abstract
A critical step in intracellular Chlamydia infection is the production of infectious progeny through the expression of late genes. This differentiation step involves conversion from a reticulate body (RB), which is the replicating form of the bacterium, into an elementary body (EB), which is the developmental form that spreads the infection to a new host cell. EUO is an important chlamydial transcription factor that controls the expression of late genes, but the mechanisms that regulate EUO are not known. We report that a plasmid-encoded protein, Pgp4, enhanced the repressor activity of EUO. Pgp4 did not function as a transcription factor because it did not bind or directly modulate transcription of its target promoters. Instead, Pgp4 increased the ability of EUO to bind and repress EUO-regulated promoters in vitro and physically interacted with EUO in pulldown assays with recombinant proteins. We detected earlier onset of EUO-dependent late gene expression by immunofluorescence microscopy in Pgp4-deficient C. trachomatis and C. muridarum strains. In addition, the absence of Pgp4 led to earlier onset of RB-to-EB conversion in C. muridarum These data support a role for Pgp4 as a negative regulator of chlamydial transcription that delays late gene expression. Our studies revealed that Pgp4 also has an EUO-independent function as a positive regulator of chlamydial transcription.IMPORTANCE Chlamydia trachomatis is an important human pathogen that causes more than 150 million active cases of genital and eye infection in the world. This obligate intracellular bacterium produces infectious progeny within an infected human cell through the expression of late chlamydial genes. We showed that the ability of a key chlamydial transcription factor, EUO, to repress late genes was enhanced by a plasmid-encoded protein, Pgp4. In addition, studies with Chlamydia Pgp4-deficient strains provide evidence that Pgp4 delays late gene expression in infected cells. Thus, Pgp4 is a novel regulator of late gene expression in Chlamydia through its ability to enhance the repressor function of EUO.
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14
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Dharamshi JE, Tamarit D, Eme L, Stairs CW, Martijn J, Homa F, Jørgensen SL, Spang A, Ettema TJG. Marine Sediments Illuminate Chlamydiae Diversity and Evolution. Curr Biol 2020; 30:1032-1048.e7. [PMID: 32142706 DOI: 10.1016/j.cub.2020.02.016] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Revised: 12/22/2019] [Accepted: 02/06/2020] [Indexed: 12/20/2022]
Abstract
The bacterial phylum Chlamydiae is so far composed of obligate symbionts of eukaryotic hosts. Well known for Chlamydiaceae, pathogens of humans and other animals, Chlamydiae also include so-called environmental lineages that primarily infect microbial eukaryotes. Environmental surveys indicate that Chlamydiae are found in a wider range of environments than anticipated previously. However, the vast majority of this chlamydial diversity has been underexplored, biasing our current understanding of their biology, ecological importance, and evolution. Here, we report that previously undetected and active chlamydial lineages dominate microbial communities in deep anoxic marine sediments taken from the Arctic Mid-Ocean Ridge. Reaching relative abundances of up to 43% of the bacterial community, and a maximum diversity of 163 different species-level taxonomic units, these Chlamydiae represent important community members. Using genome-resolved metagenomics, we reconstructed 24 draft chlamydial genomes, expanding by over a third the known genomic diversity in this phylum. Phylogenomic analyses revealed several novel clades across the phylum, including a previously unknown sister lineage of the Chlamydiaceae, providing new insights into the origin of pathogenicity in this family. We were unable to identify putative eukaryotic hosts for these marine sediment chlamydiae, despite identifying genomic features that may be indicative of host-association. The high abundance and genomic diversity of Chlamydiae in these anoxic marine sediments indicate that some members could play an important, and thus far overlooked, ecological role in such environments and may indicate alternate lifestyle strategies.
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Affiliation(s)
- Jennah E Dharamshi
- Department of Cell and Molecular Biology, Science for Life Laboratory, Uppsala University, Uppsala 75123, Sweden
| | - Daniel Tamarit
- Department of Cell and Molecular Biology, Science for Life Laboratory, Uppsala University, Uppsala 75123, Sweden; Laboratory of Microbiology, Department of Agrotechnology and Food Sciences, Wageningen University, Wageningen 6708 WE, the Netherlands
| | - Laura Eme
- Department of Cell and Molecular Biology, Science for Life Laboratory, Uppsala University, Uppsala 75123, Sweden; Unité d'Ecologie, Systématique et Evolution, CNRS, Université Paris-Sud, Orsay 91400, France
| | - Courtney W Stairs
- Department of Cell and Molecular Biology, Science for Life Laboratory, Uppsala University, Uppsala 75123, Sweden
| | - Joran Martijn
- Department of Cell and Molecular Biology, Science for Life Laboratory, Uppsala University, Uppsala 75123, Sweden; Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, NS B3H 4R2, Canada
| | - Felix Homa
- Department of Cell and Molecular Biology, Science for Life Laboratory, Uppsala University, Uppsala 75123, Sweden; Laboratory of Microbiology, Department of Agrotechnology and Food Sciences, Wageningen University, Wageningen 6708 WE, the Netherlands
| | - Steffen L Jørgensen
- Department of Earth Science, Centre for Deep Sea Research, University of Bergen, Bergen 5020, Norway
| | - Anja Spang
- Department of Cell and Molecular Biology, Science for Life Laboratory, Uppsala University, Uppsala 75123, Sweden; Department of Marine Microbiology and Biogeochemistry, NIOZ Royal Netherlands Institute for Sea Research, and Utrecht University, Den Burg 1790 AB, the Netherlands
| | - Thijs J G Ettema
- Department of Cell and Molecular Biology, Science for Life Laboratory, Uppsala University, Uppsala 75123, Sweden; Laboratory of Microbiology, Department of Agrotechnology and Food Sciences, Wageningen University, Wageningen 6708 WE, the Netherlands.
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15
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Identification of new DNA-associated proteins from Waddlia chondrophila. Sci Rep 2019; 9:4885. [PMID: 30894592 PMCID: PMC6426960 DOI: 10.1038/s41598-019-40732-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Accepted: 02/22/2019] [Indexed: 12/11/2022] Open
Abstract
Transcriptional regulation in Chlamydiae is still poorly understood. The absence until recently of genetic tools is the main cause of this gap. We discovered three new potential DNA-associated proteins of Waddlia chondrophila, a Chlamydia-related bacterium, using heparin chromatography coupled to mass spectrometry (Wcw_0377, Wcw_1456, and Wcw_1460). By ChIP-seq analysis, we determined the regulatory landscape of these three proteins and we showed that Wcw_0377 binds all along the genome whereas Wcw_1456 and _1460 possess a wide regulon with a large number of co-regulated genes. Wcw_1456 and Wcw_1460 interact with RpoD (σ66), emerging as potential RpoD regulators. On the other hand, Wcw_0377 is able to reach the host nucleus, where it might interact with eukaryotic histones through its putative chromatin-remodelling SWIB/MDM2 domain.
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16
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Lantos I, Virok DP, Mosolygó T, Rázga Z, Burián K, Endrész V. Growth characteristics of Chlamydia trachomatis in human intestinal epithelial Caco-2 cells. Pathog Dis 2018; 76:4939475. [PMID: 29635314 DOI: 10.1093/femspd/fty024] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Accepted: 03/15/2018] [Indexed: 12/13/2022] Open
Abstract
Chlamydia trachomatis is an obligate intracellular bacterium causing infections of the eyes, urogenital and respiratory tracts. Asymptomatic, repeat and chronic infections with C. trachomatis are common in the urogenital tract potentially causing severe reproductive pathology. Animal models of infection and epidemiological studies suggested the gastrointestinal tract as a reservoir of chlamydiae and as a source of repeat urogenital infections. Thus, we investigated the growth characteristics of C. trachomatis in human intestinal epithelial Caco-2 cells and the infection-induced defensin production. Immunofluorescence staining and transmission electron microscopy showed the presence of chlamydial inclusions in the cells. Chlamydial DNA and viable C. trachomatis were recovered from Caco-2 cells in similar quantity compared to that detected in the usual in vitro host cell of this bacterium. The kinetics of expression of selected C. trachomatis genes in Caco-2 cells indicated prolonged replication with persisting high expression level of late genes and of heat shock protein gene groEL. Replication of C. trachomatis induced moderate level of β-defensin-2 production by Caco-2 cells, which might contribute to avoidance of immune recognition in the intestine. According to our results, Caco-2 cells support C. trachomatis replication, suggesting that the gastrointestinal tract is a site of residence for these bacteria.
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Affiliation(s)
- Ildikó Lantos
- Department of Medical Microbiology and Immunobiology, University of Szeged, H-6720, Szeged, Dóm Sq. 10, Hungary
| | - Dezso P Virok
- Department of Medical Microbiology and Immunobiology, University of Szeged, H-6720, Szeged, Dóm Sq. 10, Hungary
| | - Tímea Mosolygó
- Department of Medical Microbiology and Immunobiology, University of Szeged, H-6720, Szeged, Dóm Sq. 10, Hungary
| | - Zsolt Rázga
- Department of Pathology, University of Szeged, H-6720, Állomás Str. 2, Hungary
| | - Katalin Burián
- Department of Medical Microbiology and Immunobiology, University of Szeged, H-6720, Szeged, Dóm Sq. 10, Hungary
| | - Valéria Endrész
- Department of Medical Microbiology and Immunobiology, University of Szeged, H-6720, Szeged, Dóm Sq. 10, Hungary
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17
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Impact of Active Metabolism on Chlamydia trachomatis Elementary Body Transcript Profile and Infectivity. J Bacteriol 2018; 200:JB.00065-18. [PMID: 29735758 DOI: 10.1128/jb.00065-18] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Accepted: 05/01/2018] [Indexed: 11/20/2022] Open
Abstract
Bacteria of the genus Chlamydia include the significant human pathogens Chlamydia trachomatis and C. pneumoniae All chlamydiae are obligate intracellular parasites that depend on infection of a host cell and transition through a biphasic developmental cycle. Following host cell invasion by the infectious elementary body (EB), the pathogen transitions to the replicative but noninfectious reticulate body (RB). Differentiation of the RB back to the EB is essential to generate infectious progeny. While the EB form has historically been regarded as metabolically inert, maintenance of infectivity during incubation with specific nutrients has revealed active maintenance of the infectious phenotype. Using transcriptome sequencing, we show that the transcriptome of extracellular EBs incubated under metabolically stimulating conditions does not cluster with germinating EBs but rather with the transcriptome of EBs isolated directly from infected cells. In addition, the transcriptional profile of the extracellular metabolizing EBs more closely resembled that of EB production than germination. Maintenance of infectivity of extracellular EBs was achieved by metabolizing chemically diverse compounds, including glucose 6-phosphate, ATP, and amino acids, all of which can be found in extracellular environments, including mucosal secretions. We further show that the EB cell type actively maintains infectivity in the inclusion after terminal differentiation. Overall, these findings contribute to the emerging understanding that the EB cell form is actively maintained through metabolic processes after terminal differentiation to facilitate prolonged infectivity within the inclusion and under host cell free conditions, for example, following deposition at mucosal surfaces.IMPORTANCE Chlamydiae are obligate intracellular Gram-negative bacteria that are responsible for a wide range of diseases in both animal and human hosts. According to the Centers for Disease Control and Prevention, C. trachomatis is the most frequently reported sexually transmitted infection in the United States, costing the American health care system nearly $2.4 billion annually. Every year, there are over 4 million new cases of Chlamydia infections in the United States and an estimated 100 million cases worldwide. To cause disease, Chlamydia must successfully complete its complex biphasic developmental cycle, alternating between an infectious cell form (EB) specialized for initiating entry into target cells and a replicative form (RB) specialized for creating and maintaining the intracellular replication niche. The EB cell form has historically been considered metabolically quiescent, a passive entity simply waiting for contact with a host cell to initiate the next round of infection. Recent studies and data presented here demonstrate that the EB maintains its infectious phenotype by actively metabolizing a variety of nutrients. Therefore, the EB appears to have an active role in chlamydial biology, possibly within multiple environments, such as mucosal surfaces, fomites, and inside the host cell after formation.
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18
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Xue Y, Zheng H, Mai Z, Qin X, Chen W, Huang T, Chen D, Zheng L. An in vitro model of azithromycin-induced persistent Chlamydia trachomatis infection. FEMS Microbiol Lett 2018; 364:3958793. [PMID: 28854672 DOI: 10.1093/femsle/fnx145] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2017] [Accepted: 07/12/2017] [Indexed: 01/26/2023] Open
Abstract
Single-dose azithromycin is recommended for treating Chlamydia trachomatis infections. Here, we established an in vitro cell model of azithromycin-induced persistent infection. Azithromycin inhibited the replication of C. trachomatis in a dose-time-dependent manner. Electron microscopy indicated that small inclusions in the induced model contained enlarged, aberrant and non-infectious reticulate bodies. RT-PCR showed that C. trachomatis still has the ability to express the unprocessed 16S rRNA gene in the model and that C. trachomatis recovered after the removal of azithromycin with a peak recovery time of 24 h. The mutations in 23S rRNA, L4 and L22 genes were not found in persistent infection, and qRT-PCR analysis showed that the relative expression level of euo in azithromycin treated infection was upregulated while omcB was downregulated. In summary, this study provides a novel in vitro cell model to examine the characteristics of azithromycin-induced persistent infection and contribute to the development of treatments for C. trachomatis infection.
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Affiliation(s)
- Yaohua Xue
- Department of Laboratory Medicine, Nanfang Hospital, Southern Medical University, No. 1838 North Guangzhou Road, Guangzhou 510515, China.,Department of Research Center, Dermatology Hospital of Southern Medical University/Guangdong Provincial Dermatology Hospital, No. 2 Lujing Road, Guangzhou 510091, China
| | - Heping Zheng
- Department of Research Center, Dermatology Hospital of Southern Medical University/Guangdong Provincial Dermatology Hospital, No. 2 Lujing Road, Guangzhou 510091, China
| | - Zhida Mai
- Department of Research Center, Dermatology Hospital of Southern Medical University/Guangdong Provincial Dermatology Hospital, No. 2 Lujing Road, Guangzhou 510091, China
| | - Xiaolin Qin
- Department of Research Center, Dermatology Hospital of Southern Medical University/Guangdong Provincial Dermatology Hospital, No. 2 Lujing Road, Guangzhou 510091, China
| | - Wentao Chen
- Department of Research Center, Dermatology Hospital of Southern Medical University/Guangdong Provincial Dermatology Hospital, No. 2 Lujing Road, Guangzhou 510091, China
| | - Tao Huang
- Department of Research Center, Dermatology Hospital of Southern Medical University/Guangdong Provincial Dermatology Hospital, No. 2 Lujing Road, Guangzhou 510091, China
| | - Daxiang Chen
- Department of Research Center, Dermatology Hospital of Southern Medical University/Guangdong Provincial Dermatology Hospital, No. 2 Lujing Road, Guangzhou 510091, China
| | - Lei Zheng
- Department of Laboratory Medicine, Nanfang Hospital, Southern Medical University, No. 1838 North Guangzhou Road, Guangzhou 510515, China
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19
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Abstract
Species of Chlamydia are the etiologic agent of endemic blinding trachoma, the leading cause of bacterial sexually transmitted diseases, significant respiratory pathogens, and a zoonotic threat. Their dependence on an intracellular growth niche and their peculiar developmental cycle are major challenges to elucidating their biology and virulence traits. The last decade has seen tremendous advances in our ability to perform a molecular genetic analysis of Chlamydia species. Major achievements include the generation of large collections of mutant strains, now available for forward- and reverse-genetic applications, and the introduction of a system for plasmid-based transformation enabling complementation of mutations; expression of foreign, modified, or reporter genes; and even targeted gene disruptions. This review summarizes the current status of the molecular genetic toolbox for Chlamydia species and highlights new insights into their biology and new challenges in the nascent field of Chlamydia genetics.
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Affiliation(s)
- Barbara S Sixt
- Department for Molecular Genetics and Microbiology, Duke University, Durham, North Carolina 27710; .,Centre de Recherche des Cordeliers, INSERM U1138, Paris 75006, France.,Université Paris Descartes, Sorbonne Paris Cité, Paris 75006, France.,Université Pierre et Marie Curie, Paris 75005, France
| | - Raphael H Valdivia
- Department for Molecular Genetics and Microbiology, Duke University, Durham, North Carolina 27710;
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20
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Collingro A, Köstlbacher S, Mussmann M, Stepanauskas R, Hallam SJ, Horn M. Unexpected genomic features in widespread intracellular bacteria: evidence for motility of marine chlamydiae. ISME JOURNAL 2017. [PMID: 28644443 PMCID: PMC5604735 DOI: 10.1038/ismej.2017.95] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Chlamydiae are obligate intracellular bacteria comprising important human pathogens and symbionts of protists. Molecular evidence indicates a tremendous diversity of chlamydiae particularly in marine environments, yet our current knowledge is based mainly on terrestrial representatives. Here we provide first insights into the biology of marine chlamydiae representing three divergent clades. Our analysis of single-cell amplified genomes revealed hallmarks of the chlamydial lifestyle, supporting the ancient origin of their characteristic developmental cycle and major virulence mechanisms. Surprisingly, these chlamydial genomes encode a complete flagellar apparatus, a previously unreported feature. We show that flagella are an ancient trait that was subject to differential gene loss among extant chlamydiae. Together with a chemotaxis system, these marine chlamydiae are likely motile, with flagella potentially playing a role during host cell infection. This study broadens our view on chlamydial biology and indicates a largely underestimated potential to adapt to different hosts and environments.
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Affiliation(s)
- Astrid Collingro
- Department of Microbial and Ecosystems Science, Division of Microbial Ecology, University of Vienna, Vienna, Austria
| | - Stephan Köstlbacher
- Department of Microbial and Ecosystems Science, Division of Microbial Ecology, University of Vienna, Vienna, Austria
| | - Marc Mussmann
- Department of Microbial and Ecosystems Science, Division of Microbial Ecology, University of Vienna, Vienna, Austria
| | | | - Steven J Hallam
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada.,Genome Science and Technology Program, University of British Columbia, Vancouver, British Columbia, Canada.,Graduate Program in Bioinformatics, University of British Columbia, Vancouver, British Columbia, Canada.,Peter Wall Institute for Advanced Studies, University of British Columbia, Vancouver, British Columbia, Canada.,ECOSCOPE Training Program, University of British Columbia, Vancouver, British Columbia, Canada
| | - Matthias Horn
- Department of Microbial and Ecosystems Science, Division of Microbial Ecology, University of Vienna, Vienna, Austria
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21
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Abstract
Chlamydia spp. are important causes of human disease for which no effective vaccine exists. These obligate intracellular pathogens replicate in a specialized membrane compartment and use a large arsenal of secreted effectors to survive in the hostile intracellular environment of the host. In this Review, we summarize the progress in decoding the interactions between Chlamydia spp. and their hosts that has been made possible by recent technological advances in chlamydial proteomics and genetics. The field is now poised to decipher the molecular mechanisms that underlie the intimate interactions between Chlamydia spp. and their hosts, which will open up many exciting avenues of research for these medically important pathogens.
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22
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de Barsy M, Frandi A, Panis G, Théraulaz L, Pillonel T, Greub G, Viollier PH. Regulatory (pan-)genome of an obligate intracellular pathogen in the PVC superphylum. ISME JOURNAL 2016; 10:2129-44. [PMID: 26953603 PMCID: PMC4989314 DOI: 10.1038/ismej.2016.23] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/10/2015] [Revised: 01/19/2016] [Accepted: 01/21/2016] [Indexed: 01/17/2023]
Abstract
Like other obligate intracellular bacteria, the Chlamydiae feature a compact regulatory genome that remains uncharted owing to poor genetic tractability. Exploiting the reduced number of transcription factors (TFs) encoded in the chlamydial (pan-)genome as a model for TF control supporting the intracellular lifestyle, we determined the conserved landscape of TF specificities by ChIP-Seq (chromatin immunoprecipitation-sequencing) in the chlamydial pathogen Waddlia chondrophila. Among 10 conserved TFs, Euo emerged as a master TF targeting >100 promoters through conserved residues in a DNA excisionase-like winged helix-turn-helix-like (wHTH) fold. Minimal target (Euo) boxes were found in conserved developmentally-regulated genes governing vertical genome transmission (cytokinesis and DNA replication) and genome plasticity (transposases). Our ChIP-Seq analysis with intracellular bacteria not only reveals that global TF regulation is maintained in the reduced regulatory genomes of Chlamydiae, but also predicts that master TFs interpret genomic information in the obligate intracellular α-proteobacteria, including the rickettsiae, from which modern day mitochondria evolved.
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Affiliation(s)
- Marie de Barsy
- Institute of Microbiology, University Hospital Center, University of Lausanne, Lausanne, Switzerland
| | - Antonio Frandi
- Department of Microbiology and Molecular Medicine, Institute of Genetics and Genomics in Geneva (iGE3), Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Gaël Panis
- Department of Microbiology and Molecular Medicine, Institute of Genetics and Genomics in Geneva (iGE3), Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Laurence Théraulaz
- Department of Microbiology and Molecular Medicine, Institute of Genetics and Genomics in Geneva (iGE3), Faculty of Medicine, University of Geneva, Geneva, Switzerland
| | - Trestan Pillonel
- Institute of Microbiology, University Hospital Center, University of Lausanne, Lausanne, Switzerland
| | - Gilbert Greub
- Institute of Microbiology, University Hospital Center, University of Lausanne, Lausanne, Switzerland
| | - Patrick H Viollier
- Department of Microbiology and Molecular Medicine, Institute of Genetics and Genomics in Geneva (iGE3), Faculty of Medicine, University of Geneva, Geneva, Switzerland
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Rosario CJ, Tan M. Regulation of Chlamydia Gene Expression by Tandem Promoters with Different Temporal Patterns. J Bacteriol 2016; 198:363-9. [PMID: 26527644 PMCID: PMC4751786 DOI: 10.1128/jb.00859-15] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Accepted: 10/24/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Chlamydia is a genus of pathogenic bacteria with an unusual intracellular developmental cycle marked by temporal waves of gene expression. The three main temporal groups of chlamydial genes are proposed to be controlled by separate mechanisms of transcriptional regulation. However, we have noted genes with discrepancies, such as the early gene dnaK and the midcycle genes bioY and pgk, which have promoters controlled by the late transcriptional regulators EUO and σ(28). To resolve this issue, we analyzed the promoters of these three genes in vitro and in Chlamydia trachomatis bacteria grown in cell culture. Transcripts from the σ(28)-dependent promoter of each gene were detected only at late times in the intracellular infection, bolstering the role of σ(28) RNA polymerase in late gene expression. In each case, however, expression prior to late times was due to a second promoter that was transcribed by σ(66) RNA polymerase, which is the major form of chlamydial polymerase. These results demonstrate that chlamydial genes can be transcribed from tandem promoters with different temporal profiles, leading to a composite expression pattern that differs from the expression profile of a single promoter. In addition, tandem promoters allow a gene to be regulated by multiple mechanisms of transcriptional regulation, such as DNA supercoiling or late regulation by EUO and σ(28). We discuss how tandem promoters broaden the repertoire of temporal gene expression patterns in the chlamydial developmental cycle and can be used to fine-tune the expression of specific genes. IMPORTANCE Chlamydia is a pathogenic bacterium that is responsible for the majority of infectious disease cases reported to the CDC each year. It causes an intracellular infection that is characterized by coordinated expression of chlamydial genes in temporal waves. Chlamydial transcription has been shown to be regulated by DNA supercoiling, alternative forms of RNA polymerase, and transcription factors, but the number of transcription factors found in Chlamydia is far fewer than the number found in most bacteria. This report describes the use of tandem promoters that allow the temporal expression of a gene or operon to be controlled by more than one regulatory mechanism. This combinatorial strategy expands the range of expression patterns that are available to regulate chlamydial genes.
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Affiliation(s)
- Christopher J Rosario
- Department of Microbiology and Molecular Genetics, University of California, Irvine, California, USA
| | - Ming Tan
- Department of Microbiology and Molecular Genetics, University of California, Irvine, California, USA Department of Medicine, University of California, Irvine, California, USA
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Abstract
The lifestyle of Chlamydiae is unique: the bacteria alternate between two morphologically distinct forms, an infectious non-replicative elementary body (EB), and a replicative, non-infectious reticulate body (RB). This review focuses on recent advances in understanding the structure and function of the infectious form of the best-studied member of the phylum, the human pathogen Chlamydia trachomatis. Once considered as an inert particle of little functional capacity, the EB is now perceived as a sophisticated entity that encounters at least three different environments during each infectious cycle. We review current knowledge on its composition and morphology, and emerging metabolic activities. These features confer resistance to the extracellular environment, the ability to penetrate a host cell and ultimately enable the EB to establish a niche enabling bacterial survival and growth. The bacterial and host molecules involved in these processes are beginning to emerge.
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25
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Orillard E, Tan M. Functional analysis of three topoisomerases that regulate DNA supercoiling levels in Chlamydia. Mol Microbiol 2015; 99:484-96. [PMID: 26447825 DOI: 10.1111/mmi.13241] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/04/2015] [Indexed: 02/01/2023]
Abstract
Chlamydia is a medically important bacterium that infects eukaryotic cells. Temporal expression of chlamydial genes during the intracellular infection is proposed to be regulated by changes in DNA supercoiling levels. To understand how chlamydial supercoiling levels are regulated, we purified and analyzed three putative Chlamydia trachomatis topoisomerases. As predicted by sequence homology, CT189/190 are the two subunits of DNA gyrase, whereas CT643 is a topoisomerase I. CT660/661 have been predicted to form a second DNA gyrase, but the reconstitute holoenzyme decatenated and relaxed DNA, indicating that the proteins are subunits of topoisomerase IV. Promoter analysis showed that each topoisomerase is transcribed from its own operon by the major chlamydial RNA polymerase. Surprisingly, all three topoisomerase promoters had higher activity from a more supercoiled DNA template. This supercoiling-responsivesness is consistent with negative feedback control of topoisomerase I and topoisomerase IV expression, which is typical of other bacteria. However, activation of the chlamydial gyrase promoter by increased supercoiling is unorthodox compared with the relaxation-induced transcription of gyrase in other bacteria. We present a model in which supercoiling levels during the intracellular chlamydial developmental cycle are regulated by unusual positive feedback control of the gyrase promoter and the temporal expression of three topoisomerases.
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Affiliation(s)
- Emilie Orillard
- Department of Microbiology and Molecular Genetics, University of California, Irvine, CA, USA
| | - Ming Tan
- Department of Microbiology and Molecular Genetics, University of California, Irvine, CA, USA.,Department of Medicine, University of California, Irvine, CA, USA
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26
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Abstract
Regulation of gene expression ensures an organism responds to stimuli and undergoes proper development. Although the regulatory networks in bacteria have been investigated in model microorganisms, nearly nothing is known about the evolution and plasticity of these networks in obligate, intracellular bacteria. The phylum Chlamydiae contains a vast array of host-associated microbes, including several human pathogens. The Chlamydiae are unique among obligate, intracellular bacteria as they undergo a complex biphasic developmental cycle in which large swaths of genes are temporally regulated. Coupled with the low number of transcription factors, these organisms offer a model to study the evolution of regulatory networks in intracellular organisms. We provide the first comprehensive analysis exploring the diversity and evolution of regulatory networks across the phylum. We utilized a comparative genomics approach to construct predicted coregulatory networks, which unveiled genus- and family-specific regulatory motifs and architectures, most notably those of virulence-associated genes. Surprisingly, our analysis suggests that few regulatory components are conserved across the phylum, and those that are conserved are involved in the exploitation of the intracellular niche. Our study thus lends insight into a component of chlamydial evolution that has otherwise remained largely unexplored.
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Affiliation(s)
- D Domman
- Department of Microbiology and Ecosystem Science, University of Vienna, Vienna, Austria
| | - M Horn
- Department of Microbiology and Ecosystem Science, University of Vienna, Vienna, Austria
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27
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Thompson CC, Griffiths C, Nicod SS, Lowden NM, Wigneshweraraj S, Fisher DJ, McClure MO. The Rsb Phosphoregulatory Network Controls Availability of the Primary Sigma Factor in Chlamydia trachomatis and Influences the Kinetics of Growth and Development. PLoS Pathog 2015; 11:e1005125. [PMID: 26313645 PMCID: PMC4552016 DOI: 10.1371/journal.ppat.1005125] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Accepted: 08/03/2015] [Indexed: 12/03/2022] Open
Abstract
Chlamydia trachomatis is an obligate intracellular human pathogen that exhibits stage-specific gene transcription throughout a biphasic developmental cycle. The mechanisms that control modulation in transcription and associated phenotypic changes are poorly understood. This study provides evidence that a switch-protein kinase regulatory network controls availability of σ66, the main sigma subunit for transcription in Chlamydia. In vitro analysis revealed that a putative switch-protein kinase regulator, RsbW, is capable of interacting directly with σ66, as well as phosphorylating its own antagonist, RsbV1, rendering it inactive. Conversely, the putative PP2C-like phosphatase domain of chlamydial RsbU was capable of reverting RsbV1 into its active state. Recent advances in genetic manipulation of Chlamydia were employed to inactivate rsbV1, as well as to increase the expression levels of rsbW or rsbV1, in vivo. Representative σ66-dependent gene transcription was repressed in the absence of rsbV1 or upon increased expression of RsbW, and increased upon elevated expression of RsbV1. These effects on housekeeping transcription were also correlated to several measures of growth and development. A model is proposed where the relative levels of active antagonist (RsbV1) and switch-protein anti-sigma factor (RsbW) control the availability of σ66 and subsequently act as a molecular 'throttle' for Chlamydia growth and development. Chlamydia trachomatis is the leading cause of both bacterial sexually transmitted infection and infection-derived blindness world-wide. No vaccine has proven protective to date in humans. C. trachomatis only replicates from inside a host cell, and has evolved to acquire a variety of nutrients directly from its host. However, a typical human immune response will normally limit the availability of a variety of essential nutrients. Thus, it is thought that the success of C. trachomatis as a human pathogen may lie in its ability to survive these immunological stress situations by slowing growth and development until conditions in the cell have improved. This mode of growth is known as persistence and how C. trachomatis senses stress and responds in this manner is an important area of research. Our report characterizes a complete signaling module, the Rsb network, that is capable of controlling the growth rate or infectivity of Chlamydia. By manipulating the levels of different pathway components, we were able to accelerate and restrict the growth and development of this pathogen. Our results suggest a mechanism by which Chlamydia can tailor its growth rate to the conditions within the host cell. The disruption of this pathway could generate a strain incapable of surviving a typical human immune response and would represent an attractive candidate as an attenuated growth vaccine.
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Affiliation(s)
- Christopher C. Thompson
- Jefferiss Trust Laboratories, Faculty of Medicine, Imperial College London, St. Mary’s Hospital Campus, London, United Kingdom
| | - Cherry Griffiths
- Jefferiss Trust Laboratories, Faculty of Medicine, Imperial College London, St. Mary’s Hospital Campus, London, United Kingdom
| | - Sophie S. Nicod
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, United Kingdom
| | - Nicole M. Lowden
- Department of Microbiology, Southern Illinois University, Carbondale, Carbondale, Illinois, United States of America
| | - Sivaramesh Wigneshweraraj
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, United Kingdom
| | - Derek J. Fisher
- Department of Microbiology, Southern Illinois University, Carbondale, Carbondale, Illinois, United States of America
| | - Myra O. McClure
- Jefferiss Trust Laboratories, Faculty of Medicine, Imperial College London, St. Mary’s Hospital Campus, London, United Kingdom
- * E-mail:
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28
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Mueller KE, Fields KA. Application of β-lactamase reporter fusions as an indicator of effector protein secretion during infections with the obligate intracellular pathogen Chlamydia trachomatis. PLoS One 2015; 10:e0135295. [PMID: 26258949 PMCID: PMC4530969 DOI: 10.1371/journal.pone.0135295] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Accepted: 07/20/2015] [Indexed: 02/05/2023] Open
Abstract
Chlamydia spp. utilize multiple secretion systems, including the type III secretion system (T3SS), to deploy host-interactive effector proteins into infected host cells. Elucidation of secreted proteins has traditionally required ectopic expression in a surrogate T3SS followed by immunolocalization of endogenous candidate effectors to confirm secretion by chlamydiae. The ability to transform Chlamydia and achieve stable expression of recombinant gene products has enabled a more direct assessment of secretion. We adapted TEM-1 β-lactamase as a reporter system for assessment of chlamydial protein secretion. We provide evidence that this system facilitates visualization of secretion in the context of infection. Specifically, our findings provide definitive evidence that C. trachomatis CT695 is secreted during infection. Follow-up indirect immunofluorescence studies confirmed CT695 secretion and indicate that this effector can be secreted at multiple points during the chlamydial developmental cycle. Our results indicate that the BlaM-fusion reporter assay will allow efficacious identification of novel secreted proteins. Moreover, this approach can easily be adapted to enable more sophisticated studies of the secretion process in Chlamydia.
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Affiliation(s)
- Konrad E. Mueller
- Department of Microbiology, Immunology & Molecular Genetics, University of Kentucky College of Medicine, Lexington, KY, United States of America
| | - Kenneth A. Fields
- Department of Microbiology, Immunology & Molecular Genetics, University of Kentucky College of Medicine, Lexington, KY, United States of America
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Chlamydia trachomatis In Vivo to In Vitro Transition Reveals Mechanisms of Phase Variation and Down-Regulation of Virulence Factors. PLoS One 2015. [PMID: 26207372 PMCID: PMC4514472 DOI: 10.1371/journal.pone.0133420] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Research on the obligate intracellular bacterium Chlamydia trachomatis demands culture in cell-lines, but the adaptive process behind the in vivo to in vitro transition is not understood. We assessed the genomic and transcriptomic dynamics underlying C. trachomatis in vitro adaptation of strains representing the three disease groups (ocular, epithelial-genital and lymphogranuloma venereum) propagated in epithelial cells over multiple passages. We found genetic features potentially underlying phase variation mechanisms mediating the regulation of a lipid A biosynthesis enzyme (CT533/LpxC), and the functionality of the cytotoxin (CT166) through an ON/OFF mechanism. We detected inactivating mutations in CT713/porB, a scenario suggesting metabolic adaptation to the available carbon source. CT135 was inactivated in a tropism-specific manner, with CT135-negative clones emerging for all epithelial-genital populations (but not for LGV and ocular populations) and rapidly increasing in frequency (~23% mutants per 10 passages). RNA-sequencing analyses revealed that a deletion event involving CT135 impacted the expression of multiple virulence factors, namely effectors known to play a role in the C. trachomatis host-cell invasion or subversion (e.g., CT456/Tarp, CT694, CT875/TepP and CT868/ChlaDub1). This reflects a scenario of attenuation of C. trachomatis virulence in vitro, which may take place independently or in a cumulative fashion with the also observed down-regulation of plasmid-related virulence factors. This issue may be relevant on behalf of the recent advances in Chlamydia mutagenesis and transformation where culture propagation for selecting mutants/transformants is mandatory. Finally, there was an increase in the growth rate for all strains, reflecting gradual fitness enhancement over time. In general, these data shed light on the adaptive process underlying the C. trachomatis in vivo to in vitro transition, and indicates that it would be prudent to restrict culture propagation to minimal passages and check the status of the CT135 genotype in order to avoid the selection of CT135-negative mutants, likely originating less virulent strains.
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