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Bachert BA, Bozue JA. Peptidoglycan enzymes of Francisella: Roles in cell morphology and pathogenesis, and potential as therapeutic targets. Front Microbiol 2023; 13:1099312. [PMID: 36713212 PMCID: PMC9877522 DOI: 10.3389/fmicb.2022.1099312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Accepted: 12/28/2022] [Indexed: 01/13/2023] Open
Abstract
Peptidoglycan, found within the cell wall of bacteria, is a structure critical for maintaining cell morphology and providing a protective barrier in diverse environments. Peptidoglycan is a remarkably dynamic structure that is constantly remodeled during cell growth and division by various peptidoglycan enzymes. Numerous peptidoglycan enzymes have been characterized from diverse bacteria and are highly sought after as targets for therapeutics. However, very little is known about these enzymes within the biothreat agent Francisella tularensis. As the causative agent of tularemia, F. tularensis is classified as a category A biothreat pathogen, in part due to its low infectious dose and lack of FDA-approved vaccine. Many bacterial species encode multiple peptidoglycan enzymes with redundant functions that allow for compensation if one of the enzymes are inactivated. In contrast, F. tularensis appears to lack this redundancy, indicating peptidoglycan enzymes may be completely essential for growth and could be exploited as targets for medical countermeasures. Indeed, several peptidoglycan enzymes in F. tularensis have been shown to play important roles in cell division, cell morphology, virulence, and modulation of host response. The aim of this review is to summarize findings from the current literature on peptidoglycan enzymes present in Francisella and discuss areas where future research efforts might be directed. We conclude that Francisella harbors a distinct set of peptidoglycan enzymes important for cell growth and virulence and represent potentially valuable targets for the development of novel therapeutics.
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Nakamura T, Shimizu T, Ikegaya R, Uda A, Watanabe K, Watarai M. Identification of pyrC gene as an immunosuppressive factor in Francisella novicida infection. Front Cell Infect Microbiol 2022; 12:1027424. [DOI: 10.3389/fcimb.2022.1027424] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Accepted: 10/13/2022] [Indexed: 11/13/2022] Open
Abstract
Francisella tularensis, a bacterial causative agent of the zoonosis tularemia, is highly pathogenic to humans. The pathogenicity of this bacterium is characterized by intracellular growth in immune cells, like macrophages, and host immune suppression. However, the detailed mechanism of immune suppression by F. tularensis is still unclear. To identify the key factors causing Francisella-mediated immunosuppression, large-scale screening using a transposon random mutant library containing 3552 mutant strains of F. tularensis subsp. novicida (F. novicida) was performed. Thirteen mutants that caused stronger tumor necrosis factor (TNF)-α production in infected U937 human macrophage cells than the wild-type F. novicida strain were isolated. Sequencing analysis of transposon insertion sites revealed 10 genes, including six novel genes, as immunosuppressive factors of Francisella. Among these, the relationship of the pyrC gene, which encodes dihydroorotase in the pyrimidine biosynthesis pathway, with Francisella-mediated immunosuppression was investigated. The pyrC deletion mutant strain (ΔpyrC) induced higher TNF-α production in U937 host cells than the wild-type F. novicida strain. The ΔpyrC mutant strain was also found to enhance host interleukin-1β and interferon (IFN)-β production. The heat-inactivated ΔpyrC mutant strain could not induce host TNF-α production. Moreover, the production of IFN-β resulting from ΔpyrC infection in U937 cells was repressed upon treatment with the stimulator of interferon genes (STING)-specific inhibitor, H-151. These results suggest that pyrC is related to the immunosuppressive activity and pathogenicity of Francisella via the STING pathway.
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Wang Q, Sun Z, Ma S, Liu X, Xia H, Chen K. Molecular mechanism and potential application of bacterial infection in the silkworm, Bombyx mori. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2022; 131:104381. [PMID: 35245606 DOI: 10.1016/j.dci.2022.104381] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2022] [Revised: 02/14/2022] [Accepted: 02/27/2022] [Indexed: 06/14/2023]
Abstract
As a representative species of Lepidoptera, Bombyx mori has been widely studied and applied. However, bacterial infection has always been an important pathogen threatening the growth of silkworms. Bombyx mori can resist various pathogenic bacteria through their own physical barrier and innate immune system. However, compared with other insects, such as Drosophila melanogaster, research on the antibacterial mechanism of silkworms is still in its infancy. This review systematically summarized the routes of bacterial infection in silkworms, the antibacterial mechanism of silkworms after ingestion or wounding infection, and the intestinal bacteria and infection of silkworms. Finally, we will discuss silkworms as a model animal for studying bacterial infectious diseases and screening antibacterial drugs.
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Affiliation(s)
- Qiang Wang
- School of Life Sciences, Jiangsu University, Zhenjiang, Jiangsu, PR China
| | - Zhonghe Sun
- School of Life Sciences, Jiangsu University, Zhenjiang, Jiangsu, PR China
| | - Shangshang Ma
- School of Food and Biological Engineering, Jiangsu University, Zhenjiang, Jiangsu, PR China
| | - Xiaoyong Liu
- School of Life Sciences, Jiangsu University, Zhenjiang, Jiangsu, PR China
| | - Hengchuan Xia
- School of Life Sciences, Jiangsu University, Zhenjiang, Jiangsu, PR China
| | - Keping Chen
- School of Life Sciences, Jiangsu University, Zhenjiang, Jiangsu, PR China.
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Watanabe K, Motonaga A, Tachibana M, Shimizu T, Watarai M. Francisella novicida can utilize Paramecium bursaria as its potential host. ENVIRONMENTAL MICROBIOLOGY REPORTS 2022; 14:50-59. [PMID: 34845838 DOI: 10.1111/1758-2229.13029] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Revised: 11/09/2021] [Accepted: 11/10/2021] [Indexed: 06/13/2023]
Abstract
Francisella novicida is a facultative intracellular pathogen and the causative agent of tularemia. Although cases of infection caused by exposure to contaminated water have been reported, its natural host and ecology in the environment remain unclear. In this study, we investigated in vitro the possibility that Paramecium bursaria may be a useful tool as a protist host model of F. novicida. Experimental infection with F. novicida resulted in a stable intracellular relationship within P. bursaria. This symbiotic intracellular relationship was not observed in experimental infections with other Francisella species and Legionella pneumophila. We found that F. novicida showed similar behaviour to that of the eukaryotic endosymbiont of P. bursaria, the green algae Chlorella, in the internalization process. In addition, stable intracellular localization of F. novicida was possible only when Chlorella was not present. Although we investigated the type VI secretion system of F. novicida as a candidate for the bacterial factor, we found that it was not involved in the establishment of an intracellular relationship with P. bursaria. These results suggested that P. bursaria is potentially a protist host model for F. novicida and may be a useful tool for understanding the relationship between protist hosts and their symbionts.
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Affiliation(s)
- Kenta Watanabe
- Laboratory of Veterinary Public Health, Joint Faculty of Veterinary Medicine, Yamaguchi University, Yamaguchi, Japan
| | - Akane Motonaga
- Laboratory of Veterinary Public Health, Joint Faculty of Veterinary Medicine, Yamaguchi University, Yamaguchi, Japan
| | - Masato Tachibana
- National BioResource Project Paramecium, Joint Faculty of Veterinary Medicine, Yamaguchi University, Yamaguchi, Japan
| | - Takashi Shimizu
- Laboratory of Veterinary Public Health, Joint Faculty of Veterinary Medicine, Yamaguchi University, Yamaguchi, Japan
| | - Masahisa Watarai
- Laboratory of Veterinary Public Health, Joint Faculty of Veterinary Medicine, Yamaguchi University, Yamaguchi, Japan
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Jang H, Do H, Kim CM, Kim GE, Lee JH, Park HH. Molecular basis of dimerization of lytic transglycosylase revealed by the crystal structure of MltA from Acinetobacter baumannii. IUCRJ 2021; 8:921-930. [PMID: 34804545 PMCID: PMC8562663 DOI: 10.1107/s2052252521008666] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/12/2021] [Accepted: 08/18/2021] [Indexed: 06/13/2023]
Abstract
Peptidoglycan digestion by murein-degrading enzymes is a critical process in bacterial cell growth and/or cell division. The membrane-bound lytic murein transglycosylase A (MltA) is a murein-degrading enzyme; it catalyzes the cleavage of the β-1,4-glycosidic linkage between N-acetylmuramic acid and N-acetylglucosamine in peptidoglycans. Although substrate recognition and cleavage by MltA have been examined by previous structural and mutagenesis studies, the overall mechanism of MltA in conjunction with other functionally related molecules on the outer membrane of bacterial cells for peptidoglycan degradation has remained elusive. In this study, the crystal structure of MltA from the virulent human pathogen Acinetobacter baumannii is characterized and presented. The study indicated that MltA from A. baumannii forms homodimers via an extra domain which is specific to this species. Furthermore, the working mechanism of MltA with various functionally related proteins on the bacterial outer membrane was modeled based on the structural and biochemical analysis.
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Affiliation(s)
- Hyunseok Jang
- College of Pharmacy, Chung-Ang University, Seoul 06974, Republic of Korea
- Department of Global Innovative Drugs, Graduate School of Chung-Ang University, Seoul 06974, Republic of Korea
| | - Hackwon Do
- Unit of Research for Practical Application, Korea Polar Research Institute, Incheon 21990, Republic of Korea
- Department of Polar Sciences, University of Science and Technology, Incheon 21990, Republic of Korea
| | - Chang Min Kim
- Department of Global Innovative Drugs, Graduate School of Chung-Ang University, Seoul 06974, Republic of Korea
| | - Gi Eob Kim
- College of Pharmacy, Chung-Ang University, Seoul 06974, Republic of Korea
- Department of Global Innovative Drugs, Graduate School of Chung-Ang University, Seoul 06974, Republic of Korea
| | - Jun Hyuck Lee
- Unit of Research for Practical Application, Korea Polar Research Institute, Incheon 21990, Republic of Korea
- Department of Polar Sciences, University of Science and Technology, Incheon 21990, Republic of Korea
| | - Hyun Ho Park
- College of Pharmacy, Chung-Ang University, Seoul 06974, Republic of Korea
- Department of Global Innovative Drugs, Graduate School of Chung-Ang University, Seoul 06974, Republic of Korea
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Rytter H, Jamet A, Ziveri J, Ramond E, Coureuil M, Lagouge-Roussey P, Euphrasie D, Tros F, Goudin N, Chhuon C, Nemazanyy I, de Moraes FE, Labate C, Guerrera IC, Charbit A. The pentose phosphate pathway constitutes a major metabolic hub in pathogenic Francisella. PLoS Pathog 2021; 17:e1009326. [PMID: 34339477 PMCID: PMC8360588 DOI: 10.1371/journal.ppat.1009326] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 08/12/2021] [Accepted: 07/14/2021] [Indexed: 11/19/2022] Open
Abstract
Metabolic pathways are now considered as intrinsic virulence attributes of pathogenic bacteria and thus represent potential targets for antibacterial strategies. Here we focused on the role of the pentose phosphate pathway (PPP) and its connections with other metabolic pathways in the pathophysiology of Francisella novicida. The involvement of the PPP in the intracellular life cycle of Francisella was first demonstrated by studying PPP inactivating mutants. Indeed, we observed that inactivation of the tktA, rpiA or rpe genes severely impaired intramacrophage multiplication during the first 24 hours. However, time-lapse video microscopy demonstrated that rpiA and rpe mutants were able to resume late intracellular multiplication. To better understand the links between PPP and other metabolic networks in the bacterium, we also performed an extensive proteo-metabolomic analysis of these mutants. We show that the PPP constitutes a major bacterial metabolic hub with multiple connections to glycolysis, the tricarboxylic acid cycle and other pathways, such as fatty acid degradation and sulfur metabolism. Altogether our study highlights how PPP plays a key role in the pathogenesis and growth of Francisella in its intracellular niche.
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Affiliation(s)
- Héloise Rytter
- Université de Paris, Paris, France
- INSERM U1151 - CNRS UMR 8253, Institut Necker-Enfants Malades. Team 7: Pathogénie des Infections Systémiques, Paris, France
| | - Anne Jamet
- Université de Paris, Paris, France
- INSERM U1151 - CNRS UMR 8253, Institut Necker-Enfants Malades. Team 7: Pathogénie des Infections Systémiques, Paris, France
| | - Jason Ziveri
- Université de Paris, Paris, France
- INSERM U1151 - CNRS UMR 8253, Institut Necker-Enfants Malades. Team 7: Pathogénie des Infections Systémiques, Paris, France
| | - Elodie Ramond
- Université de Paris, Paris, France
- INSERM U1151 - CNRS UMR 8253, Institut Necker-Enfants Malades. Team 7: Pathogénie des Infections Systémiques, Paris, France
| | - Mathieu Coureuil
- Université de Paris, Paris, France
- INSERM U1151 - CNRS UMR 8253, Institut Necker-Enfants Malades. Team 7: Pathogénie des Infections Systémiques, Paris, France
| | - Pauline Lagouge-Roussey
- Université de Paris, Paris, France
- INSERM U1151 - CNRS UMR 8253, Institut Necker-Enfants Malades. Team 7: Pathogénie des Infections Systémiques, Paris, France
| | - Daniel Euphrasie
- Université de Paris, Paris, France
- INSERM U1151 - CNRS UMR 8253, Institut Necker-Enfants Malades. Team 7: Pathogénie des Infections Systémiques, Paris, France
| | - Fabiola Tros
- Université de Paris, Paris, France
- INSERM U1151 - CNRS UMR 8253, Institut Necker-Enfants Malades. Team 7: Pathogénie des Infections Systémiques, Paris, France
| | - Nicolas Goudin
- Pole Bio-analyse d’images, Structure Fédérative de Recherche Necker INSERM US24- CNRS UMS 3633, Paris, France
| | - Cerina Chhuon
- Université de Paris, Paris, France
- Plateforme Protéome Institut Necker, PPN, Structure Fédérative de Recherche Necker INSERM US24-CNRS UMS 3633, Paris, France
| | - Ivan Nemazanyy
- Université de Paris, Paris, France
- Plateforme Etude du métabolisme, Structure Fédérative de Recherche Necker INSERM US24-CNRS UMS 3633, Paris, France
| | - Fabricio Edgar de Moraes
- Laboratório Max Feffer de Genética de Plantas, Departamento de Genética, Escola Superior de Agricultura Luiz de Queiroz, Universidade de São Paulo, Piracicaba, Brazil
| | - Carlos Labate
- Laboratório Max Feffer de Genética de Plantas, Departamento de Genética, Escola Superior de Agricultura Luiz de Queiroz, Universidade de São Paulo, Piracicaba, Brazil
| | - Ida Chiara Guerrera
- Université de Paris, Paris, France
- Plateforme Protéome Institut Necker, PPN, Structure Fédérative de Recherche Necker INSERM US24-CNRS UMS 3633, Paris, France
- * E-mail: (ICG); (AC)
| | - Alain Charbit
- Université de Paris, Paris, France
- INSERM U1151 - CNRS UMR 8253, Institut Necker-Enfants Malades. Team 7: Pathogénie des Infections Systémiques, Paris, France
- * E-mail: (ICG); (AC)
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