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Fisher DJ, Beare PA. Recent advances in genetic systems in obligate intracellular human-pathogenic bacteria. Front Cell Infect Microbiol 2023; 13:1202245. [PMID: 37404720 PMCID: PMC10315504 DOI: 10.3389/fcimb.2023.1202245] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Accepted: 05/22/2023] [Indexed: 07/06/2023] Open
Abstract
The ability to genetically manipulate a pathogen is fundamental to discovering factors governing host-pathogen interactions at the molecular level and is critical for devising treatment and prevention strategies. While the genetic "toolbox" for many important bacterial pathogens is extensive, approaches for modifying obligate intracellular bacterial pathogens were classically limited due in part to the uniqueness of their obligatory lifestyles. Many researchers have confronted these challenges over the past two and a half decades leading to the development of multiple approaches to construct plasmid-bearing recombinant strains and chromosomal gene inactivation and deletion mutants, along with gene-silencing methods enabling the study of essential genes. This review will highlight seminal genetic achievements and recent developments (past 5 years) for Anaplasma spp., Rickettsia spp., Chlamydia spp., and Coxiella burnetii including progress being made for the still intractable Orientia tsutsugamushi. Alongside commentary of the strengths and weaknesses of the various approaches, future research directions will be discussed to include methods for C. burnetii that should have utility in the other obligate intracellular bacteria. Collectively, the future appears bright for unraveling the molecular pathogenic mechanisms of these significant pathogens.
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Affiliation(s)
- Derek J. Fisher
- School of Biological Sciences, Southern Illinois University, Carbondale, IL, United States
| | - Paul A. Beare
- Rocky Mountain Laboratory, National Institute of Health, Hamilton, MT, United States
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Atwal S, Wongsantichon J, Giengkam S, Saharat K, Pittayasathornthun YJ, Chuenklin S, Wang LC, Chung T, Huh H, Lee SH, Sobota RM, Salje J. The obligate intracellular bacterium Orientia tsutsugamushi differentiates into a developmentally distinct extracellular state. Nat Commun 2022; 13:3603. [PMID: 35739103 PMCID: PMC9226355 DOI: 10.1038/s41467-022-31176-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Accepted: 06/03/2022] [Indexed: 11/13/2022] Open
Abstract
Orientia tsutsugamushi (Ot) is an obligate intracellular bacterium in the family Rickettsiaceae that causes scrub typhus, a severe mite-borne human disease. Its mechanism of cell exit is unusual amongst Rickettsiaceae, as Ot buds off the surface of infected cells enveloped in plasma membrane. Here, we show that Ot bacteria that have budded out of host cells are in a distinct developmental stage compared with intracellular bacteria. We refer to these two stages as intracellular and extracellular bacteria (IB and EB, respectively). These two forms differ in physical properties: IB is both round and elongated, and EB is round. Additionally, IB has higher levels of peptidoglycan and is physically robust compared with EB. The two bacterial forms differentially express proteins involved in bacterial physiology and host-pathogen interactions, specifically those involved in bacterial dormancy and stress response, and outer membrane autotransporter proteins ScaA and ScaC. Whilst both populations are infectious, entry of IB Ot is sensitive to inhibitors of both clathrin-mediated endocytosis and macropinocytosis, whereas entry of EB Ot is only sensitive to a macropinocytosis inhibitor. Our identification and detailed characterization of two developmental forms of Ot significantly advances our understanding of the intracellular lifecycle of an important human pathogen. Orientia tsutsugamushi (Ot) the causing agent of scrub typhus exits infected cells using a unique mechanism that involves budding off the surface of infected cells. Here, Atwal et al. report that Ots that have budded from their host cells are in a distinct developmental stage than intracellular bacteria and provide the first characterization of this extracellular stage. Both forms are infectious but differ in their physical properties, proteome, and entry mechanism into host cells.
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Affiliation(s)
- Sharanjeet Atwal
- Public Health Research Institute, Rutgers the State University of New Jersey, Newark, NJ, USA
| | - Jantana Wongsantichon
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Suparat Giengkam
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Kittirat Saharat
- Public Health Research Institute, Rutgers the State University of New Jersey, Newark, NJ, USA
| | | | - Suthida Chuenklin
- Public Health Research Institute, Rutgers the State University of New Jersey, Newark, NJ, USA.,Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Loo Chien Wang
- Functional Proteomics Laboratory, Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore.,SingMass-National Mass Spectrometry Laboratory, Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
| | - Taerin Chung
- Institute for Quantitative Biomedicine, Rutgers University, Piscataway, NJ, USA
| | - Hyun Huh
- Institute for Quantitative Biomedicine, Rutgers University, Piscataway, NJ, USA
| | - Sang-Hyuk Lee
- Institute for Quantitative Biomedicine, Rutgers University, Piscataway, NJ, USA.,Department of Physics and Astronomy, Rutgers University, Piscataway, NJ, USA
| | - Radoslaw M Sobota
- Functional Proteomics Laboratory, Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore.,SingMass-National Mass Spectrometry Laboratory, Institute of Molecular and Cell Biology, Agency for Science, Technology and Research (A*STAR), Singapore, Singapore
| | - Jeanne Salje
- Public Health Research Institute, Rutgers the State University of New Jersey, Newark, NJ, USA. .,Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand. .,Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK.
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Wang Z, Xing B. Small-molecule fluorescent probes: big future for specific bacterial labeling and infection detection. Chem Commun (Camb) 2021; 58:155-170. [PMID: 34882159 DOI: 10.1039/d1cc05531c] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Bacterial infections remain a global healthcare problem that is particularly attributed to the spread of antibiotic resistance and the evolving pathogenicity. Accurate and swift approaches for infection diagnosis are urgently needed to facilitate antibiotic stewardship and effective medical treatment. Direct optical imaging for specific bacterial labeling and infection detection offers an attractive prospect of precisely monitoring the infectious disease status and therapeutic response in real time. This feature article focuses on the recent advances of small-molecule probes developed for fluorescent imaging of bacteria and infection, which covers the probe design, responsive mechanisms and representative applications. In addition, the perspective and challenges to advance small-molecule fluorescent probes in the field of rapid drug-resistant bacterial detection and clinical diagnosis of bacterial infections are discussed. We envision that the continuous advancement and clinical translations of such a technique will have a strong impact on future anti-infective medicine.
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Affiliation(s)
- Zhimin Wang
- Advanced Research Institute of Multidisciplinary Science, Beijing Institute of Technology, Beijing 100081, China.
| | - Bengang Xing
- Division of Chemistry and Biological Chemistry, School of Physical & Mathematical Sciences, Nanyang Technological University, 637371, Singapore. .,School of Chemical & Biomedical Engineering, Nanyang Technological University, Singapore, 637459, Singapore
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Feaga HA, Dworkin J. Transcription regulates ribosome hibernation. Mol Microbiol 2021; 116:663-673. [PMID: 34152658 PMCID: PMC8628635 DOI: 10.1111/mmi.14762] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Revised: 05/17/2021] [Accepted: 05/24/2021] [Indexed: 11/26/2022]
Abstract
Most bacteria are quiescent, typically as a result of nutrient limitation. In order to minimize energy consumption during this potentially prolonged state, quiescent bacteria substantially attenuate protein synthesis, the most energetically costly cellular process. Ribosomes in quiescent bacteria are present as dimers of two 70S ribosomes. Dimerization is dependent on a single protein, hibernation promoting factor (HPF), that binds the ribosome in the mRNA channel. This interaction indicates that dimers are inactive, suggesting that HPF inhibits translation. However, we observe that HPF does not significantly affect protein synthesis in vivo suggesting that dimerization is a consequence of inactivity, not the cause. The HPF-dimer interaction further implies that re-initiation of translation when the bacteria exit quiescence requires dimer resolution. We show that ribosome dimers quickly resolve in the presence of nutrients, and this resolution is dependent on transcription, indicating that mRNA synthesis is required for dimer resolution. Finally, we observe that ectopic HPF expression in growing cells where mRNA is abundant does not significantly affect protein synthesis despite stimulating dimer formation, suggesting that dimerization is dynamic. Thus, the extensive transcription that occurs in response to nutrient availability rapidly re-activates the translational apparatus of a quiescent cell and induces dimer resolution.
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Affiliation(s)
| | - Jonathan Dworkin
- Department of Microbiology and Immunology, College of Physicians and Surgeons, Columbia University, New York, NY 10032
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Salje J. Cells within cells: Rickettsiales and the obligate intracellular bacterial lifestyle. Nat Rev Microbiol 2021; 19:375-390. [PMID: 33564174 DOI: 10.1038/s41579-020-00507-2] [Citation(s) in RCA: 71] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/16/2020] [Indexed: 01/01/2023]
Abstract
The Rickettsiales are a group of obligate intracellular vector-borne Gram-negative bacteria that include many organisms of clinical and agricultural importance, including Anaplasma spp., Ehrlichia chaffeensis, Wolbachia, Rickettsia spp. and Orientia tsutsugamushi. This Review provides an overview of the current state of knowledge of the biology of these bacteria and their interactions with host cells, with a focus on pathogenic species or those that are otherwise important for human health. This includes a description of rickettsial genomics, bacterial cell biology, the intracellular lifestyles of Rickettsiales and the mechanisms by which they induce and evade the innate immune response.
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Affiliation(s)
- Jeanne Salje
- Centre for Tropical Medicine and Global Health, Nuffield Department of Medicine, University of Oxford, Oxford, UK. .,Mahidol Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand. .,Public Health Research Institute, Rutgers University, Newark, NJ, USA.
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