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Granados-Tristán AL, Hernández-Luna CE, González-Escalante LA, Camacho-Moll ME, Silva-Ramírez B, Bermúdez de León M, Peñuelas-Urquides K. ESX-3 secretion system in Mycobacterium: An overview. Biochimie 2024; 216:46-55. [PMID: 37879428 DOI: 10.1016/j.biochi.2023.10.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 09/26/2023] [Accepted: 10/22/2023] [Indexed: 10/27/2023]
Abstract
Mycobacteria are microorganisms distributed in the environment worldwide, and some of them, such as Mycobacterium tuberculosis or M. leprae, are pathogenic. The hydrophobic mycobacterial cell envelope has low permeation and bacteria need to export products across their structure. Mycobacteria possess specialized protein secretion systems, such as the Early Secretory Antigenic Target 6 secretion (ESX) system. Five ESX loci have been described in M. tuberculosis, called ESX-1 to ESX-5. The ESX-3 secretion system has been associated with mycobacterial metabolism and growth. The locus of this system is highly conserved across mycobacterial species. Metallo-proteins regulate negative ESX-3 transcription in high conditions of iron and zinc. Moreover, this secretion system is part of an antioxidant regulatory pathway linked to Zinc. EccA3, EccB3, EccC3, EccD3, and EccE3 are components of the ESX-3 secretion machinery, whereas EsxG-EsxH, PE5-PPE4, and PE15-PPE20 are proteins secreted by this system. In addition, EspG3 and MycP3 are complementary proteins involved in transport and proteolysis respectively. This system is associated to mycobacterial virulence by releasing the bacteria from the phagosome and inhibiting endomembrane damage response. Furthermore, components of this system inhibit the host immune response by reducing the recognition of M. tuberculosis-infected cells. The components of the ESX-3 secretion system play a role in drug resistance and cell wall integrity. Moreover, the expression data of this system indicated that external and internal factors affect ESX-3 locus expression. This review provides an overview of new findings on the ESX-3 secretion system, its regulation, expression, and functions.
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Affiliation(s)
- Ana Laura Granados-Tristán
- Departamento de Biología Molecular, Centro de Investigación Biomédica del Noreste, Instituto Mexicano del Seguro Social, Monterrey, 64720, Nuevo León, Mexico; Universidad Autónoma de Nuevo León, Facultad de Ciencias Biológicas, San Nicolás de los Garza, 66455, Nuevo León, Mexico.
| | - Carlos Eduardo Hernández-Luna
- Universidad Autónoma de Nuevo León, Facultad de Ciencias Biológicas, San Nicolás de los Garza, 66455, Nuevo León, Mexico.
| | - Laura Adiene González-Escalante
- Departamento de Biología Molecular, Centro de Investigación Biomédica del Noreste, Instituto Mexicano del Seguro Social, Monterrey, 64720, Nuevo León, Mexico.
| | - María Elena Camacho-Moll
- Departamento de Biología Molecular, Centro de Investigación Biomédica del Noreste, Instituto Mexicano del Seguro Social, Monterrey, 64720, Nuevo León, Mexico.
| | - Beatriz Silva-Ramírez
- Departamento de Inmunogenética, Centro de Investigación Biomédica del Noreste, Instituto Mexicano del Seguro Social, Monterrey, 64720, Nuevo León, Mexico.
| | - Mario Bermúdez de León
- Departamento de Biología Molecular, Centro de Investigación Biomédica del Noreste, Instituto Mexicano del Seguro Social, Monterrey, 64720, Nuevo León, Mexico.
| | - Katia Peñuelas-Urquides
- Departamento de Biología Molecular, Centro de Investigación Biomédica del Noreste, Instituto Mexicano del Seguro Social, Monterrey, 64720, Nuevo León, Mexico.
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Tan CG, Oberlag NM, McGowan AE, Dawrs SN, Chan YL, Strong M, Hasan NA, Honda JR. Genomic and microbiological analyses of iron acquisition pathways among respiratory and environmental nontuberculous mycobacteria from Hawai'i. Front Microbiol 2023; 14:1268963. [PMID: 38029173 PMCID: PMC10667711 DOI: 10.3389/fmicb.2023.1268963] [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: 08/01/2023] [Accepted: 10/11/2023] [Indexed: 12/01/2023] Open
Abstract
As environmental opportunistic pathogens, nontuberculous mycobacteria (NTM) can cause severe and difficult to treat pulmonary disease. In the United States, Hawai'i has the highest prevalence of infection. Rapid growing mycobacteria (RGM) such as Mycobacterium abscessus and M. porcinum and the slow growing mycobacteria (SGM) including M. intracellulare subspecies chimaera are common environmental NTM species and subspecies in Hawai'i. Although iron acquisition is an essential process of many microorganisms, iron acquisition via siderophores among the NTM is not well-characterized. In this study, we apply genomic and microbiological methodologies to better understand iron acquisition via siderophores for environmental and respiratory isolates of M. abscessus, M. porcinum, and M. intracellulare subspecies chimaera from Hawai'i. Siderophore synthesis and transport genes, including mycobactin (mbt), mmpL/S, and esx-3 were compared among 47 reference isolates, 29 respiratory isolates, and 23 environmental Hawai'i isolates. Among all reference isolates examined, respiratory isolates showed significantly more siderophore pertinent genes compared to environmental isolates. Among the Hawai'i isolates, RGM M. abscessus and M. porcinum had significantly less esx-3 and mbt genes compared to SGM M. chimaera when stratified by growth classification. However, no significant differences were observed between the species when grown on low iron culture agar or siderophore production by the chrome azurol S (CAS) assay in vitro. These results indicate the complex mechanisms involved in iron sequestration and siderophore activity among diverse NTM species.
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Affiliation(s)
| | - Nicole M. Oberlag
- Center for Genes, Environment and Health, National Jewish Health, Denver, CO, United States
| | | | - Stephanie N. Dawrs
- Center for Genes, Environment and Health, National Jewish Health, Denver, CO, United States
| | | | - Michael Strong
- Center for Genes, Environment and Health, National Jewish Health, Denver, CO, United States
| | - Nabeeh A. Hasan
- Center for Genes, Environment and Health, National Jewish Health, Denver, CO, United States
| | - Jennifer R. Honda
- Center for Genes, Environment and Health, National Jewish Health, Denver, CO, United States
- Department of Cellular and Molecular Biology, School of Medicine, The University of Texas Health Science Center at Tyler, Tyler, TX, United States
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Li X, Chen L, Wang Y, Guo X, He ZG. Zinc excess impairs Mycobacterium bovis growth through triggering a Zur-IdeR-iron homeostasis signal pathway. Microbiol Spectr 2023; 11:e0106923. [PMID: 37668384 PMCID: PMC10580935 DOI: 10.1128/spectrum.01069-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Accepted: 07/15/2023] [Indexed: 09/06/2023] Open
Abstract
Zinc excess is toxic to bacteria and, thus, represents an important innate defense mechanism of host cells, especially against mycobacterial infections. However, the signaling pathway triggered by zinc excess and its relationship with iron homeostasis remain poorly understood in mycobacteria. Here, we characterize a novel Zur-IdeR-iron homeostasis signaling pathway that modulates the growth of Mycobacterium bovis under zinc toxicity. We found that the regulator Zur interacts with the iron-homeostasis regulator IdeR, enhancing the DNA-binding ability of IdeR. Excess zinc disrupts this interaction and represses ideR transcription through Zur, which promotes the expression of iron uptake genes and leads to the accumulation of intracellular iron in M. bovis. The elevated iron levels lower the bacterial survival ability under excess zinc stress. Consistently, deleting zur hinders intracellular iron accumulation of M. bovis and enhances bacterial growth under stress, while silencing ideR impairs the growth of the wild-type and zur-deleted strains under the same conditions. Interestingly, both Zur and IdeR are conserved in bacteria facing zinc toxicity. Overall, our work uncovers a novel antimicrobial signal pathway whereby zinc excess disrupts iron homeostasis, which may deepen our understanding of the crosstalk mechanism between iron and zinc homeostasis in bacteria.IMPORTANCEAs a catalytic and structural cofactor of proteins, zinc is essential for almost all living organisms. However, zinc excess is toxic and represents a vital innate immunity strategy of macrophages to combat intracellular pathogens, especially against mycobacterial pathogens such as Mycobacterium tuberculosis, the causative agent of tuberculosis. Here, we first characterize an antibacterial signaling pathway of zinc excess and its relationship with iron homeostasis in M. bovis. We found that excess zinc inhibits the transcription of ideR and its DNA-binding activity through Zur, which, in turn, promotes the expression of iron uptake genes, causes intracellular iron accumulation, and finally impairs the bacterial growth. This study reveals the existence of the Zur-IdeR-iron homeostasis pathway triggered by zinc excess in M. bovis, which will shed light on the crosstalk mechanisms between zinc and iron homeostasis in bacteria and the antimicrobial mechanisms of host-mediated zinc toxicity.
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Affiliation(s)
- Xiaohui Li
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangxi Research Center for Microbial and Enzyme Engineering Technology, College of Life Science and Technology, Guangxi University, Nanning, Guangxi, China
| | - Liu Chen
- College of Life Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, China
| | - Yuankun Wang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangxi Research Center for Microbial and Enzyme Engineering Technology, College of Life Science and Technology, Guangxi University, Nanning, Guangxi, China
| | - Xiao Guo
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangxi Research Center for Microbial and Enzyme Engineering Technology, College of Life Science and Technology, Guangxi University, Nanning, Guangxi, China
| | - Zheng-Guo He
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, Guangxi Research Center for Microbial and Enzyme Engineering Technology, College of Life Science and Technology, Guangxi University, Nanning, Guangxi, China
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Li B, He S, Tan Z, Li A, Fan J, Zhao L, Zhang Z, Chu H. Impaired ESX-3 Induces Bedaquiline Persistence in Mycobacterium abscessus Growing Under Iron-Limited Conditions. SMALL METHODS 2023; 7:e2300183. [PMID: 37291735 DOI: 10.1002/smtd.202300183] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2023] [Revised: 05/15/2023] [Indexed: 06/10/2023]
Abstract
ESX-3 is a secretion pathway which is essential for mycobactin-mediated iron acquisition under iron-limited conditions. Although present in all Mycobacterium sp., ESX-3 remains to be elucidated in Mycobacterium abscessus. In the study reported here, impaired ESX-3 seriously restricts the growth of M. abscesses under iron-limited conditions; growth is salvaged by functional ESX-3 or iron supplementation. Notably, impaired ESX-3 does not kill M. abscesses when environmental iron is insufficient but induces persistence to bedaquiline, a diarylquinoline class antibiotic used to treat multidrug-resistant mycobacteria. One potential mechanism contributing to persistence is the iron deficiency due to impaired ESX-3 suppressing succinate dehydrogenase activity, which dysregulates the tricarboxylic acid cycle and inactivates bedaquiline. Experiments conducted here also demonstrate that the regulator, MtrA, can bind ESX-3 and promote the survival of M. abscessus. As such, this study suggests that a novel pathway involving MtrA, ESX-3, iron metabolism, and the TCA cycle contributes to bedaquiline persistence in M. abscesses growing under iron-limited conditions.
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Affiliation(s)
- Bing Li
- Department of Respiratory and Critical Care Medicine, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, 200433, China
- School of Medicine, Tongji University, Shanghai, 200092, China
| | - Siyuan He
- Department of Respiratory and Critical Care Medicine, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, 200433, China
- School of Medicine, Tongji University, Shanghai, 200092, China
| | - Zhili Tan
- Department of Respiratory and Critical Care Medicine, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, 200433, China
- School of Medicine, Tongji University, Shanghai, 200092, China
| | - Anqi Li
- Department of Respiratory and Critical Care Medicine, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, 200433, China
- School of Medicine, Tongji University, Shanghai, 200092, China
| | - Junsheng Fan
- Department of Respiratory and Critical Care Medicine, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, 200433, China
- School of Medicine, Tongji University, Shanghai, 200092, China
| | - Lan Zhao
- Department of Respiratory and Critical Care Medicine, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, 200433, China
- School of Medicine, Tongji University, Shanghai, 200092, China
| | - Zhemin Zhang
- Department of Respiratory and Critical Care Medicine, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, 200433, China
- School of Medicine, Tongji University, Shanghai, 200092, China
| | - Haiqing Chu
- Department of Respiratory and Critical Care Medicine, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, 200433, China
- School of Medicine, Tongji University, Shanghai, 200092, China
- Shanghai Key Laboratory of Tuberculosis, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, 200433, China
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Sankey N, Merrick H, Singh P, Rogers J, Reddi A, Hartson SD, Mitra A. Role of the Mycobacterium tuberculosis ESX-4 Secretion System in Heme Iron Utilization and Pore Formation by PPE Proteins. mSphere 2023; 8:e0057322. [PMID: 36749044 PMCID: PMC10117145 DOI: 10.1128/msphere.00573-22] [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: 11/15/2022] [Accepted: 01/16/2023] [Indexed: 02/08/2023] Open
Abstract
Mycobacterium tuberculosis (Mtb) is transmitted through aerosols and primarily colonizes within the lung. The World Health Organization estimates that Mtb kills ~1.4 million people every year. A key aspect that makes Mtb such a successful pathogen is its ability to overcome iron limitation mounted by the host immune response. In our previous studies, we have shown that Mtb can utilize iron from heme, the largest source of iron in the human host, and that it uses two redundant heme utilization pathways. In this study, we show that the ESX-4 type VII secretion system (T7SS) is necessary for extracellular heme uptake into the Mtb cell through both heme utilization pathways. ESX-4 influences the secretion of the culture filtrate proteins Rv0125 and Rv1085c, which are also necessary for efficient heme utilization. We also discovered that deletion of the alternative sigma factor SigM significantly reduced Mtb heme utilization through both pathways and predict that SigM is a global positive regulator of core heme utilization genes of both pathways. Finally, we present the first direct evidence that some mycobacterial PPE (proline-proline-glutamate motif) proteins of the PPE protein family are pore-forming membrane proteins. Altogether, we identified core components of both Mtb Heme utilization pathways that were previously unknown and identified a novel channel-forming membrane protein of Mtb. IMPORTANCE M. tuberculosis (Mtb) is completely dependent on iron acquisition in the host to cause disease. The largest source of iron for Mtb in the human host is heme. Here, we show that the ancestral ESX-4 type VII secretion system is required for the efficient utilization of heme as a source of iron, which is an essential nutrient. This is another biological function identified for ESX-4 in Mtb, whose contribution to Mtb physiology is poorly understood. A most exciting finding is that some mycobacterial PPE (proline-proline-glutamate motif) proteins that have been implicated in the nutrient acquisition are membrane proteins that can form channels in a lipid bilayer. These observations have far-reaching implications because they support an emerging theme that PPE proteins can function as channel proteins in the outer mycomembrane for nutrient acquisition. Mtb has evolved a heme uptake system that is drastically different from all other known bacterial heme acquisition systems.
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Affiliation(s)
- November Sankey
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, Oklahoma, USA
| | - Haley Merrick
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, Oklahoma, USA
| | - Padam Singh
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, Oklahoma, USA
| | - Janet Rogers
- Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, Oklahoma, USA
| | - Amit Reddi
- School of Chemistry and Biochemistry, Parker Petit Institute for Bioengineering and Biosciences, Georgia Institute of Technology, Atlanta, Georgia, USA
| | - Steven D. Hartson
- Department of Biochemistry and Molecular Biology, Oklahoma State University, Stillwater, Oklahoma, USA
| | - Avishek Mitra
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, Oklahoma, USA
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Bythrow GV, Farhat MF, Levendosky K, Mohandas P, Germain GA, Yoo B, Quadri LEN. Mycobacterium abscessus Mutants with a Compromised Functional Link between the Type VII ESX-3 System and an Iron Uptake Mechanism Reliant on an Unusual Mycobactin Siderophore. Pathogens 2022; 11:pathogens11090953. [PMID: 36145386 PMCID: PMC9505556 DOI: 10.3390/pathogens11090953] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Revised: 08/12/2022] [Accepted: 08/18/2022] [Indexed: 11/28/2022] Open
Abstract
The opportunistic pathogen Mycobacterium abscessus subsp. abscessus (Mab) has become an emerging public health threat due to the increasing number of Mab-associated chronic pulmonary disease cases. Treatment requires multiple drug courses and is often combined with surgical resection. Cure rates are only ~50% due to treatment failure and comorbidities. Deeper understanding of the biology of Mab is required to illuminate potential avenues for the development of better therapeutics against Mab infections. The ESX-3 type VII protein secretion system of Mab has an important role in host inflammatory and pathological responses during infection. In this work, we demonstrate a functional link between ESX-3 and an iron uptake system based on an unusual mycobactin-type siderophore (designated MBT Ab) and exploit this link to implement a large screen for transposon mutants with an impaired ESX-3. Most mutants we identified carry insertions in genes encoding predicted ESX-3 secretion machinery components or potential ESX-3 substrates. The mutants overproduce MBT Ab, a trait consistent with an iron uptake defect. Our characterization of MBT Ab revealed structural features reminiscent of nocardial mycobactin-like compounds with cytotoxicity. This finding raises the possibility that MBT Ab may play roles in pathogenesis unlinked to iron homeostasis. The mutants generated herein will facilitate research to better understand the role of ESX-3 and its interplay with the siderophore system.
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Affiliation(s)
- Glennon V. Bythrow
- Department of Biology, Brooklyn College, City University of New York, 2900 Bedford Avenue, Brooklyn, NY 11210, USA
- Biology Program, Graduate Center, City University of New York, 365 Fifth Avenue, New York, NY 10016, USA
| | - Manal F. Farhat
- Department of Biology, Brooklyn College, City University of New York, 2900 Bedford Avenue, Brooklyn, NY 11210, USA
- Biology Program, Graduate Center, City University of New York, 365 Fifth Avenue, New York, NY 10016, USA
| | - Keith Levendosky
- Department of Biology, Brooklyn College, City University of New York, 2900 Bedford Avenue, Brooklyn, NY 11210, USA
- Biology Program, Graduate Center, City University of New York, 365 Fifth Avenue, New York, NY 10016, USA
| | - Poornima Mohandas
- Department of Biology, Brooklyn College, City University of New York, 2900 Bedford Avenue, Brooklyn, NY 11210, USA
- Biology Program, Graduate Center, City University of New York, 365 Fifth Avenue, New York, NY 10016, USA
| | - Gabrielle A. Germain
- Department of Biology, Brooklyn College, City University of New York, 2900 Bedford Avenue, Brooklyn, NY 11210, USA
- Biology Program, Graduate Center, City University of New York, 365 Fifth Avenue, New York, NY 10016, USA
| | - Barney Yoo
- Department of Chemistry, Hunter College, City University of New York, 695 Park Avenue, New York, NY 10065, USA
| | - Luis E. N. Quadri
- Department of Biology, Brooklyn College, City University of New York, 2900 Bedford Avenue, Brooklyn, NY 11210, USA
- Biology Program, Graduate Center, City University of New York, 365 Fifth Avenue, New York, NY 10016, USA
- Biochemistry Program, Graduate Center, City University of New York, 365 Fifth Avenue, New York, NY 10016, USA
- Correspondence:
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Gauthier DT, Doss JH, LaGatta M, Gupta T, Karls RK, Quinn FD. Genomic Degeneration and Reduction in the Fish Pathogen Mycobacterium shottsii. Microbiol Spectr 2022; 10:e0115821. [PMID: 35579461 PMCID: PMC9241763 DOI: 10.1128/spectrum.01158-21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Accepted: 04/26/2022] [Indexed: 01/17/2023] Open
Abstract
Mycobacterium shottsii is a dysgonic, nonpigmented mycobacterium originally isolated from diseased striped bass (Morone saxatilis) in the Chesapeake Bay, USA. Genomic analysis reveals that M. shottsii is a Mycobacterium ulcerans/Mycobacterium marinum clade (MuMC) member, but unlike the superficially similar M. pseudoshottsii, also isolated from striped bass, it is not an M. ulcerans ecovar, instead belonging to a transitional group of strains basal to proposed "Aronson" and "M" lineages. Although phylogenetically distinct from the human pathogen M. ulcerans, the M. shottsii genome shows parallel but nonhomologous genomic degeneration, including massive accumulation of pseudogenes accompanied by proliferation of unique insertion sequences (ISMysh01, ISMysh03), large-scale deletions, and genomic reorganization relative to typical M. marinum strains. Coupled with its observed ecological characteristics and loss of chromogenicity, the genomic structure of M. shottsii is suggestive of evolution toward a state of obligate pathogenicity, as observed for other Mycobacterium spp., including M. ulcerans, M. tuberculosis, and M. leprae. IMPORTANCE Morone saxatilis (striped bass) is an ecologically and economically important finfish species on the United States east coast. Mycobacterium shottsii and Mycobacterium pseudoshottsii were originally described in the early 2000s as novel species from outbreaks of visceral and dermal mycobacteriosis in this species. Biochemical and genetic characterization place these species within the Mycobacterium ulcerans/M. marinum clade (MuMC), and M. pseudoshottsii has been proposed as an ecovar of M. ulcerans. Here, we describe the complete genome of M. shottsii, demonstrating that it is clearly not an M. ulcerans ecovar; however, it has undergone parallel genomic modification suggestive of a transition to obligate pathogenicity. As in M. ulcerans, the M. shottsii genome demonstrates widespread pseudogene formation driven by proliferation of insertion sequences, as well as genomic reorganization. This work clarifies the phylogenetic position of M. shottsii relative to other MuMC members and provides insight into processes shaping its genomic structure.
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Affiliation(s)
- D. T. Gauthier
- Department of Biological Sciences, Old Dominion University, Norfolk, Virginia, USA
| | - J. H. Doss
- Department of Biological Sciences, Old Dominion University, Norfolk, Virginia, USA
| | - M. LaGatta
- Department of Infectious Diseases, University of Georgia, Athens, Georgia, USA
- Pathens Incorporated, Athens, Georgia, USA
| | - T. Gupta
- Department of Infectious Diseases, University of Georgia, Athens, Georgia, USA
| | - R. K. Karls
- Department of Infectious Diseases, University of Georgia, Athens, Georgia, USA
- Pathens Incorporated, Athens, Georgia, USA
| | - F. D. Quinn
- Department of Infectious Diseases, University of Georgia, Athens, Georgia, USA
- Pathens Incorporated, Athens, Georgia, USA
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Dwivedi M, Bajpai K. The chamber of secretome in Mycobacterium tuberculosis as a potential therapeutic target. Biotechnol Genet Eng Rev 2022; 39:1-44. [PMID: 35613080 DOI: 10.1080/02648725.2022.2076031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Mycobacterium tuberculosis (MTB) causes one of the ancient diseases, Tuberculosis, affects people around the globe and its severity can be understood by its classification as a second infectious disease after COVID-19 and the 13th leading cause of death according to a WHO report. Despite having advanced diagnostic approaches and therapeutic strategies, unfortunately, TB is still spreading across the population due to the emergence of drug-resistance MTB and Latent TB infection (LTBI). We are seeking for effective approaches to overcome these hindrances and efficient treatment for this perilous disease. Therefore, there is an urgent need to develop drugs based on operative targeting of the bacterial system that could result in both efficient treatment and lesser emergence of MDR-TB. One such promising target could be the secretory systems and especially the Type 7 secretory system (T7SS-ESX) of Mycobacterium tuberculosis, which is crucial for the secretion of effector proteins as well as in establishing host-pathogen interactions of the tubercle bacilli. The five paralogous ESX systems (ESX-1 to EXS-5) have been observed by in silico genome analysis of MTB, among which ESX-1 and ESX-5 are substantial for virulence and mediating host cellular inflammasome. The bacterium growth and virulence can be modulated by targeting the T7SS. In the present review, we demonstrate the current status of therapeutics against MTB and focus on the function and cruciality of T7SS along with other secretory systems as a promising therapeutic target against Tuberculosis.
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Affiliation(s)
- Manish Dwivedi
- Amity Institute of Biotechnology, Amity University Uttar Pradesh, Lucknow, India
| | - Kriti Bajpai
- Department of Biotechnology, Himachal Pradesh University, Shimla, India
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Multiple genetic paths including massive gene amplification allow Mycobacterium tuberculosis to overcome loss of ESX-3 secretion system substrates. Proc Natl Acad Sci U S A 2022; 119:2112608119. [PMID: 35193958 PMCID: PMC8872769 DOI: 10.1073/pnas.2112608119] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/18/2021] [Indexed: 01/18/2023] Open
Abstract
The Mycobacterium tuberculosis (Mtb) ESX-3 type VII secretion system plays a critical role in iron acquisition. Infection of mice with highly attenuated Mtb deletion mutants lacking esxG or esxH, genes encoding key ESX-3 substrates, unexpectedly yielded suppressor mutants with restored capacity to grow in vivo and in vitro in the absence of iron supplementation. Whole-genome sequencing identified two mechanisms of suppression, the disruption of a transcriptional repressor that regulates expression of an ESX-3 paralogous region encoding EsxR and EsxS, and a massive 38- to 60-fold gene amplification of this same region. These data are significant because they reveal a previously unrecognized iron acquisition regulon and inform mechanisms of Mtb chromosome evolution. Mycobacterium tuberculosis (Mtb) possesses five type VII secretion systems (T7SS), virulence determinants that include the secretion apparatus and associated secretion substrates. Mtb strains deleted for the genes encoding substrates of the ESX-3 T7SS, esxG or esxH, require iron supplementation for in vitro growth and are highly attenuated in vivo. In a subset of infected mice, suppressor mutants of esxG or esxH deletions were isolated, which enabled growth to high titers or restored virulence. Suppression was conferred by mechanisms that cause overexpression of an ESX-3 paralogous region that lacks genes for the secretion apparatus but encodes EsxR and EsxS, apparent ESX-3 orphan substrates that functionally compensate for the lack of EsxG or EsxH. The mechanisms include the disruption of a transcriptional repressor and a massive 38- to 60-fold gene amplification. These data identify an iron acquisition regulon, provide insight into T7SS, and reveal a mechanism of Mtb chromosome evolution involving “accordion-type” amplification.
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Rivera-Calzada A, Famelis N, Llorca O, Geibel S. Type VII secretion systems: structure, functions and transport models. Nat Rev Microbiol 2021; 19:567-584. [PMID: 34040228 DOI: 10.1038/s41579-021-00560-5] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/09/2021] [Indexed: 02/07/2023]
Abstract
Type VII secretion systems (T7SSs) have a key role in the secretion of effector proteins in non-pathogenic mycobacteria and pathogenic mycobacteria such as Mycobacterium tuberculosis, the main causative agent of tuberculosis. Tuberculosis-causing mycobacteria, still accounting for 1.4 million deaths annually, rely on paralogous T7SSs to survive in the host and efficiently evade its immune response. Although it is still unknown how effector proteins of T7SSs cross the outer membrane of the diderm mycobacterial cell envelope, recent advances in the structural characterization of these secretion systems have revealed the intricate network of interactions of conserved components in the plasma membrane. This structural information, added to recent advances in the molecular biology and regulation of mycobacterial T7SSs as well as progress in our understanding of their secreted effector proteins, is shedding light on the inner working of the T7SS machinery. In this Review, we highlight the implications of these studies and the derived transport models, which provide new scenarios for targeting the deathly human pathogen M. tuberculosis.
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Affiliation(s)
- Angel Rivera-Calzada
- Structural Biology Programme, Spanish National Cancer Research Centre (CNIO), Madrid, Spain.
| | - Nikolaos Famelis
- Institute for Molecular Infection Biology, Julius-Maximilian University of Würzburg, Würzburg, Germany.,Rudolf Virchow Center for Integrative and Translational Biomedicine, Julius-Maximilian University of Würzburg, Würzburg, Germany
| | - Oscar Llorca
- Structural Biology Programme, Spanish National Cancer Research Centre (CNIO), Madrid, Spain
| | - Sebastian Geibel
- Institute for Molecular Infection Biology, Julius-Maximilian University of Würzburg, Würzburg, Germany. .,Rudolf Virchow Center for Integrative and Translational Biomedicine, Julius-Maximilian University of Würzburg, Würzburg, Germany.
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11
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Bendre AD, Peters PJ, Kumar J. Recent Insights into the Structure and Function of Mycobacterial Membrane Proteins Facilitated by Cryo-EM. J Membr Biol 2021; 254:321-341. [PMID: 33954837 PMCID: PMC8099146 DOI: 10.1007/s00232-021-00179-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2020] [Accepted: 03/23/2021] [Indexed: 12/26/2022]
Abstract
Mycobacterium tuberculosis (Mtb) is one of the deadliest pathogens encountered by humanity. Over the decades, its characteristic membrane organization and composition have been understood. However, there is still limited structural information and mechanistic understanding of the constituent membrane proteins critical for drug discovery pipelines. Recent advances in single-particle cryo-electron microscopy and cryo-electron tomography have provided the much-needed impetus towards structure determination of several vital Mtb membrane proteins whose structures were inaccessible via X-ray crystallography and NMR. Important insights into membrane composition and organization have been gained via a combination of electron tomography and biochemical and biophysical assays. In addition, till the time of writing this review, 75 new structures of various Mtb proteins have been reported via single-particle cryo-EM. The information obtained from these structures has improved our understanding of the mechanisms of action of these proteins and the physiological pathways they are associated with. These structures have opened avenues for structure-based drug design and vaccine discovery programs that might help achieve global-TB control. This review describes the structural features of selected membrane proteins (type VII secretion systems, Rv1819c, Arabinosyltransferase, Fatty Acid Synthase, F-type ATP synthase, respiratory supercomplex, ClpP1P2 protease, ClpB disaggregase and SAM riboswitch), their involvement in physiological pathways, and possible use as a drug target. Tuberculosis is a deadly disease caused by Mycobacterium tuberculosis. The Cryo-EM and tomography have simplified the understanding of the mycobacterial membrane organization. Some proteins are located in the plasma membrane; some span the entire envelope, while some, like MspA, are located in the mycomembrane. Cryo-EM has made the study of such membrane proteins feasible.
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Affiliation(s)
- Ameya D Bendre
- Laboratory of Membrane Protein Biology, National Centre for Cell Science, NCCS Complex, S. P. Pune University Campus, Ganeshkhind, Pune, Maharashtra, 411007, India
| | - Peter J Peters
- The Maastricht Multimodal Molecular Imaging Institute (M4I), Division of Nanoscopy, Maastricht University, Maastricht, The Netherlands
| | - Janesh Kumar
- Laboratory of Membrane Protein Biology, National Centre for Cell Science, NCCS Complex, S. P. Pune University Campus, Ganeshkhind, Pune, Maharashtra, 411007, India.
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12
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Mycobacterium tuberculosis Small RNA MTS1338 Confers Pathogenic Properties to Non-Pathogenic Mycobacterium smegmatis. Microorganisms 2021; 9:microorganisms9020414. [PMID: 33671144 PMCID: PMC7921967 DOI: 10.3390/microorganisms9020414] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Revised: 02/14/2021] [Accepted: 02/15/2021] [Indexed: 11/16/2022] Open
Abstract
Small non-coding RNAs play a key role in bacterial adaptation to various stresses. Mycobacterium tuberculosis small RNA MTS1338 is upregulated during mycobacteria infection of macrophages, suggesting its involvement in the interaction of the pathogen with the host. In this study, we explored the functional effects of MTS1338 by expressing it in non-pathogenic Mycobacterium smegmatis that lacks the MTS1338 gene. The results indicated that MTS1338 slowed the growth of the recombinant mycobacteria in culture and increased their survival in RAW 264.7 macrophages, where the MTS1338-expressing strain significantly (p < 0.05) reduced the number of mature phagolysosomes and changed the production of cytokines IL-1β, IL-6, IL-10, IL-12, TGF-β, and TNF-α compared to those of the control strain. Proteomic and secretomic profiling of recombinant and control strains revealed differential expression of proteins involved in the synthesis of main cell wall components and in the regulation of iron metabolism (ESX-3 secretion system) and response to hypoxia (furA, whiB4, phoP). These effects of MTS1338 expression are characteristic for M. tuberculosis during infection, suggesting that in pathogenic mycobacteria MTS1338 plays the role of a virulence factor supporting the residence of M. tuberculosis in the host.
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13
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Soares de Melo C, Singh V, Myrick A, Simelane SB, Taylor D, Brunschwig C, Lawrence N, Schnappinger D, Engelhart CA, Kumar A, Parish T, Su Q, Myers TG, Boshoff HIM, Barry CE, Sirgel FA, van Helden PD, Buchanan KI, Bayliss T, Green SR, Ray PC, Wyatt PG, Basarab GS, Eyermann CJ, Chibale K, Ghorpade SR. Antitubercular 2-Pyrazolylpyrimidinones: Structure-Activity Relationship and Mode-of-Action Studies. J Med Chem 2021; 64:719-740. [PMID: 33395287 PMCID: PMC7816196 DOI: 10.1021/acs.jmedchem.0c01727] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Indexed: 11/30/2022]
Abstract
Phenotypic screening of a Medicines for Malaria Venture compound library against Mycobacterium tuberculosis (Mtb) identified a cluster of pan-active 2-pyrazolylpyrimidinones. The biology triage of these actives using various tool strains of Mtb suggested a novel mechanism of action. The compounds were bactericidal against replicating Mtb and retained potency against clinical isolates of Mtb. Although selected MmpL3 mutant strains of Mtb showed resistance to these compounds, there was no shift in the minimum inhibitory concentration (MIC) against a mmpL3 hypomorph, suggesting mutations in MmpL3 as a possible resistance mechanism for the compounds but not necessarily as the target. RNA transcriptional profiling and the checkerboard board 2D-MIC assay in the presence of varying concentrations of ferrous salt indicated perturbation of the Fe-homeostasis by the compounds. Structure-activity relationship studies identified potent compounds with good physicochemical properties and in vitro microsomal metabolic stability with moderate selectivity over cytotoxicity against mammalian cell lines.
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Affiliation(s)
- Candice Soares de Melo
- Drug
Discovery and Development Centre (H3D), Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - Vinayak Singh
- Drug
Discovery and Development Centre (H3D), University of Cape Town, Rondebosch 7701, South Africa
- South
African Medical Research Council Drug Discovery and Development Research
Unit, Department of Chemistry and Institute of Infectious Disease
and Molecular Medicine, University of Cape
Town, Rondebosch 7701, South Africa
| | - Alissa Myrick
- Drug
Discovery and Development Centre (H3D), University of Cape Town, Rondebosch 7701, South Africa
| | - Sandile B. Simelane
- Drug
Discovery and Development Centre (H3D), Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - Dale Taylor
- Drug
Discovery and Development Centre (H3D), Division of Clinical Pharmacology,
Department of Medicine, University of Cape
Town, Observatory 7925, South Africa
| | - Christel Brunschwig
- Drug
Discovery and Development Centre (H3D), Division of Clinical Pharmacology,
Department of Medicine, University of Cape
Town, Observatory 7925, South Africa
| | - Nina Lawrence
- Drug
Discovery and Development Centre (H3D), Division of Clinical Pharmacology,
Department of Medicine, University of Cape
Town, Observatory 7925, South Africa
| | - Dirk Schnappinger
- Department
of Microbiology and Immunology, Weill Cornell
Medical College, New York, New York 10065, United States
| | - Curtis A. Engelhart
- Department
of Microbiology and Immunology, Weill Cornell
Medical College, New York, New York 10065, United States
| | - Anuradha Kumar
- Infectious
Disease Research Institute, 1616 Eastlake Ave E, Suite 400, Seattle, Washington 98102, United States
| | - Tanya Parish
- Infectious
Disease Research Institute, 1616 Eastlake Ave E, Suite 400, Seattle, Washington 98102, United States
| | - Qin Su
- Genomic
Technologies Section, Research Technologies Branch, National Institute of Allergy and Infectious Diseases, National Institutes
of Health, Bethesda, Maryland 20892, United
States
| | - Timothy G. Myers
- Genomic
Technologies Section, Research Technologies Branch, National Institute of Allergy and Infectious Diseases, National Institutes
of Health, Bethesda, Maryland 20892, United
States
| | - Helena I. M. Boshoff
- Tuberculosis
Research Section, Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases,
National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Clifton E. Barry
- Tuberculosis
Research Section, Laboratory of Clinical Infectious Diseases, National Institute of Allergy and Infectious Diseases,
National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Frederick A. Sirgel
- South
African Medical Research Council Centre for Tuberculosis Research/DST/NRF
Centre of Excellence for Biomedical Tuberculosis Research, Division
of Molecular Biology and Human Genetics, Faculty of Medicine and Health
Science, Stellenbosch University, Tygerberg 7505, South Africa
| | - Paul D. van Helden
- South
African Medical Research Council Centre for Tuberculosis Research/DST/NRF
Centre of Excellence for Biomedical Tuberculosis Research, Division
of Molecular Biology and Human Genetics, Faculty of Medicine and Health
Science, Stellenbosch University, Tygerberg 7505, South Africa
| | - Kirsteen I. Buchanan
- Drug
Discovery Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, U.K.
| | - Tracy Bayliss
- Drug
Discovery Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, U.K.
| | - Simon R. Green
- Drug
Discovery Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, U.K.
| | - Peter C. Ray
- Drug
Discovery Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, U.K.
| | - Paul G. Wyatt
- Drug
Discovery Unit, School of Life Sciences, University of Dundee, Dundee DD1 5EH, U.K.
| | - Gregory S. Basarab
- Drug
Discovery and Development Centre (H3D), Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
- Drug
Discovery and Development Centre (H3D), Division of Clinical Pharmacology,
Department of Medicine, University of Cape
Town, Observatory 7925, South Africa
| | - Charles J. Eyermann
- Drug
Discovery and Development Centre (H3D), Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - Kelly Chibale
- Drug
Discovery and Development Centre (H3D), Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
- South
African Medical Research Council Drug Discovery and Development Research
Unit, Department of Chemistry and Institute of Infectious Disease
and Molecular Medicine, University of Cape
Town, Rondebosch 7701, South Africa
| | - Sandeep R. Ghorpade
- Drug
Discovery and Development Centre (H3D), Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
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14
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Yimer SA, Kalayou S, Homberset H, Birhanu AG, Riaz T, Zegeye ED, Lutter T, Abebe M, Holm-Hansen C, Aseffa A, Tønjum T. Lineage-Specific Proteomic Signatures in the Mycobacterium tuberculosis Complex Reveal Differential Abundance of Proteins Involved in Virulence, DNA Repair, CRISPR-Cas, Bioenergetics and Lipid Metabolism. Front Microbiol 2020; 11:550760. [PMID: 33072011 PMCID: PMC7536270 DOI: 10.3389/fmicb.2020.550760] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Accepted: 08/17/2020] [Indexed: 01/17/2023] Open
Abstract
Despite the discovery of the tubercle bacillus more than 130 years ago, its physiology and the mechanisms of virulence are still not fully understood. A comprehensive analysis of the proteomes of members of the human-adapted Mycobacterium tuberculosis complex (MTBC) lineages 3, 4, 5, and 7 was conducted to better understand the evolution of virulence and other physiological characteristics. Unique and shared proteomic signatures in these modern, pre-modern and ancient MTBC lineages, as deduced from quantitative bioinformatics analyses of high-resolution mass spectrometry data, were delineated. The main proteomic findings were verified by using immunoblotting. In addition, analysis of multiple genome alignment of members of the same lineages was performed. Label-free peptide quantification of whole cells from MTBC lineages 3, 4, 5, and 7 yielded a total of 38,346 unique peptides derived from 3092 proteins, representing 77% coverage of the predicted proteome. MTBC lineage-specific differential expression was observed for 539 proteins. Lineage 7 exhibited a markedly reduced abundance of proteins involved in DNA repair, type VII ESX-3 and ESX-1 secretion systems, lipid metabolism and inorganic phosphate uptake, and an increased abundance of proteins involved in alternative pathways of the TCA cycle and the CRISPR-Cas system as compared to the other lineages. Lineages 3 and 4 exhibited a higher abundance of proteins involved in virulence, DNA repair, drug resistance and other metabolic pathways. The high throughput analysis of the MTBC proteome by super-resolution mass spectrometry provided an insight into the differential expression of proteins between MTBC lineages 3, 4, 5, and 7 that may explain the slow growth and reduced virulence, metabolic flexibility, and the ability to survive under adverse growth conditions of lineage 7.
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Affiliation(s)
- Solomon Abebe Yimer
- Unit for Genome Dynamics, Department of Microbiology, University of Oslo, Oslo, Norway.,Coalition for Epidemic Preparedness Innovations, Oslo, Norway
| | - Shewit Kalayou
- Division of Laboratory Medicine, Department of Microbiology, Oslo University Hospital, Oslo, Norway.,International Centre of Insect Physiology and Ecology, Nairobi, Kenya
| | - Håvard Homberset
- Unit for Genome Dynamics, Department of Microbiology, University of Oslo, Oslo, Norway
| | - Alemayehu Godana Birhanu
- Unit for Genome Dynamics, Department of Microbiology, University of Oslo, Oslo, Norway.,Division of Laboratory Medicine, Department of Microbiology, Oslo University Hospital, Oslo, Norway.,Institute of Biotechnology, Addis Ababa University, Addis Ababa, Ethiopia
| | - Tahira Riaz
- Unit for Genome Dynamics, Department of Microbiology, University of Oslo, Oslo, Norway
| | - Ephrem Debebe Zegeye
- NORCE Norwegian Research Centre AS, Centre for Applied Biotechnology, Bergen, Norway
| | - Timo Lutter
- Unit for Genome Dynamics, Department of Microbiology, University of Oslo, Oslo, Norway
| | - Markos Abebe
- Armauer Hansen Research Institute, Addis Ababa, Ethiopia
| | - Carol Holm-Hansen
- Division of Infection Control and Environmental Health, Norwegian Institute of Public Health, Oslo, Norway
| | - Abraham Aseffa
- Armauer Hansen Research Institute, Addis Ababa, Ethiopia
| | - Tone Tønjum
- Unit for Genome Dynamics, Department of Microbiology, University of Oslo, Oslo, Norway.,Division of Laboratory Medicine, Department of Microbiology, Oslo University Hospital, Oslo, Norway
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15
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Bunduc CM, Bitter W, Houben E. Structure and Function of the Mycobacterial Type VII Secretion Systems. Annu Rev Microbiol 2020; 74:315-335. [DOI: 10.1146/annurev-micro-012420-081657] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Bacteria have evolved intricate secretion machineries for the successful delivery of large molecules across their cell envelopes. Such specialized secretion systems allow a variety of bacteria to thrive in specific host environments. In mycobacteria, type VII secretion systems (T7SSs) are dedicated protein transport machineries that fulfill diverse and crucial roles, ranging from metabolite uptake to immune evasion and subversion to conjugation. Since the discovery of mycobacterial T7SSs about 15 y ago, genetic, structural, and functional studies have provided insight into the roles and functioning of these secretion machineries. Here, we focus on recent advances in the elucidation of the structure and mechanism of mycobacterial T7SSs in protein secretion. As many of these systems are essential for mycobacterial growth or virulence, they provide opportunities for the development of novel therapies to combat a number of relevant mycobacterial diseases.
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Affiliation(s)
- Catalin M. Bunduc
- Section of Molecular Microbiology, Amsterdam Institute of Molecular and Life Sciences, Vrije Universiteit Amsterdam, 1081 HZ Amsterdam, The Netherlands
| | - W. Bitter
- Section of Molecular Microbiology, Amsterdam Institute of Molecular and Life Sciences, Vrije Universiteit Amsterdam, 1081 HZ Amsterdam, The Netherlands
- Department of Medical Microbiology and Infection Control, Amsterdam Infection and Immunity Institute, Amsterdam University Medical Centers, 1007 MB Amsterdam, The Netherlands
| | - E.N.G. Houben
- Section of Molecular Microbiology, Amsterdam Institute of Molecular and Life Sciences, Vrije Universiteit Amsterdam, 1081 HZ Amsterdam, The Netherlands
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16
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Kannan N, Haug M, Steigedal M, Flo TH. Mycobacterium smegmatis Vaccine Vector Elicits CD4+ Th17 and CD8+ Tc17 T Cells With Therapeutic Potential to Infections With Mycobacterium avium. Front Immunol 2020; 11:1116. [PMID: 32582196 PMCID: PMC7296097 DOI: 10.3389/fimmu.2020.01116] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2019] [Accepted: 05/07/2020] [Indexed: 11/13/2022] Open
Abstract
Mycobacterium avium (Mav) complex is increasingly reported to cause non-tuberculous infections in individuals with a compromised immune system. Treatment is complicated and no vaccines are available. Previous studies have shown some potential of using genetically modified Mycobacterium smegmatis (Msm) as a vaccine vector to tuberculosis since it is non-pathogenic and thus would be tolerated by immunocompromised individuals. In this study, we used a mutant strain of Msm disrupted in EspG3, a component of the ESX-3 secretion system. Infection of macrophages and dendritic cells with Msm ΔespG3 showed increased antigen presentation compared to cells infected with wild-type Msm. Vaccination of mice with Msm ΔespG3, expressing the Mav antigen MPT64, provided equal protection against Mav infection as the tuberculosis vaccine, Mycobacterium bovis BCG. However, upon challenge with Mav, we observed a high frequency of IL-17-producing CD4+ (Th17 cells) and CD8+ (Tc17 cells) T cells in mice vaccinated with Msm ΔespG3::mpt64 that was not seen in BCG-vaccinated mice. Adoptive transfer of cells from Msm ΔespG3-vaccinated mice showed that cells from the T cell compartment contributed to protection from Mav infection. Further experiments revealed Tc17-enriched T cells did not provide prophylactic protection against subsequent Mav infection, but a therapeutic effect was observed when Tc17-enriched cells were transferred to mice already infected with Mav. These initial findings are important, as they suggest a previously unknown role of Tc17 cells in mycobacterial infections. Taken together, Msm ΔespG3 shows promise as a vaccine vector against Mav and possibly other (myco)bacterial infections.
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Affiliation(s)
- Nisha Kannan
- Center of Molecular Inflammation Research and Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
| | - Markus Haug
- Center of Molecular Inflammation Research and Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology (NTNU), Trondheim, Norway.,Department of Infectious Diseases, St. Olavs University Hospital, Trondheim, Norway
| | - Magnus Steigedal
- Center of Molecular Inflammation Research and Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology (NTNU), Trondheim, Norway.,Department of Infectious Diseases, St. Olavs University Hospital, Trondheim, Norway
| | - Trude Helen Flo
- Center of Molecular Inflammation Research and Department of Clinical and Molecular Medicine, Norwegian University of Science and Technology (NTNU), Trondheim, Norway
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17
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Abstract
The translocation of proteins across membranes is a fundamental cellular function. Bacteria have evolved a striking array of pathways for delivering proteins into or across cytoplasmic membranes and, when present, outer membranes. Translocated proteins can form part of the membrane landscape, reside in the periplasmic space situated between the inner and outer membranes of Gram-negative bacteria, deposit on the cell surface, or be released to the extracellular milieu or injected directly into target cells. One protein translocation system, the general secretory pathway, is conserved in all domains of life. A second, the twin-arginine translocation pathway, is also phylogenetically distributed among most bacteria and plant chloroplasts. While all cell types have evolved additional systems dedicated to the translocation of protein cargoes, the number of such systems in bacteria is now known to exceed nine. These dedicated protein translocation systems, which include the types 1 through 9 secretion systems (T1SSs-T9SSs), the chaperone-usher pathway, and type IV pilus system, are the subject of this review. Most of these systems were originally identified and have been extensively characterized in Gram-negative or diderm (two-membrane) species. It is now known that several of these systems also have been adapted to function in Gram-positive or monoderm (single-membrane) species, and at least one pathway is found only in monoderms. This review briefly summarizes the distinctive mechanistic and structural features of each dedicated pathway, as well as the shared properties, that together account for the broad biological diversity of protein translocation in bacteria.
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Affiliation(s)
- Peter J Christie
- Department of Microbiology and Molecular Genetics, McGovern Medical School, 6431 Fannin St., Houston, TX, USA.
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18
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Tateishi Y, Minato Y, Baughn AD, Ohnishi H, Nishiyama A, Ozeki Y, Matsumoto S. Genome-wide identification of essential genes in Mycobacterium intracellulare by transposon sequencing - Implication for metabolic remodeling. Sci Rep 2020; 10:5449. [PMID: 32214196 PMCID: PMC7096427 DOI: 10.1038/s41598-020-62287-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2019] [Accepted: 03/10/2020] [Indexed: 12/20/2022] Open
Abstract
The global incidence of the human nontuberculous mycobacteria (NTM) disease is rapidly increasing. However, knowledge of gene essentiality under optimal growth conditions and conditions relevant to the natural ecology of NTM, such as hypoxia, is lacking. In this study, we utilized transposon sequencing to comprehensively identify genes essential for growth in Mycobacterium intracellulare. Of 5126 genes of M. intracellulare ATCC13950, 506 genes were identified as essential genes, of which 280 and 158 genes were shared with essential genes of M. tuberculosis and M. marinum, respectively. The shared genes included target genes of existing antituberculous drugs including SQ109, which targets the trehalose monomycolate transporter MmpL3. From 175 genes showing decreased fitness as conditionally essential under hypoxia, preferential carbohydrate metabolism including gluconeogenesis, glyoxylate cycle and succinate production was suggested under hypoxia. Virulence-associated genes including proteasome system and mycothiol redox system were also identified as conditionally essential under hypoxia, which was further supported by the higher effective suppression of bacterial growth under hypoxia compared to aerobic conditions in the presence of these inhibitors. This study has comprehensively identified functions essential for growth of M. intracellulare under conditions relevant to the host environment. These findings provide critical functional genomic information for drug discovery.
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Affiliation(s)
- Yoshitaka Tateishi
- Department of Bacteriology, Graduate School of Medical and Dental Sciences, Niigata University, 1-757, Asahimachi-Dori, Chuo-ku, Niigata, 951-8510, Japan.
| | - Yusuke Minato
- Department of Microbiology and Immunology, University of Minnesota Medical School, 689 23rd Avenue S.E. Microbiology Research Facility, Minneapolis, 55455, MN, USA
| | - Anthony D Baughn
- Department of Microbiology and Immunology, University of Minnesota Medical School, 689 23rd Avenue S.E. Microbiology Research Facility, Minneapolis, 55455, MN, USA
| | - Hiroaki Ohnishi
- Department of Laboratory Medicine, Kyorin University School of Medicine, Tokyo, Japan
| | - Akihito Nishiyama
- Department of Bacteriology, Graduate School of Medical and Dental Sciences, Niigata University, 1-757, Asahimachi-Dori, Chuo-ku, Niigata, 951-8510, Japan
| | - Yuriko Ozeki
- Department of Bacteriology, Graduate School of Medical and Dental Sciences, Niigata University, 1-757, Asahimachi-Dori, Chuo-ku, Niigata, 951-8510, Japan
| | - Sohkichi Matsumoto
- Department of Bacteriology, Graduate School of Medical and Dental Sciences, Niigata University, 1-757, Asahimachi-Dori, Chuo-ku, Niigata, 951-8510, Japan
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19
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Grüber G. Introduction: Novel insights into TB research and drug discovery. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2020; 152:2-5. [PMID: 32087187 DOI: 10.1016/j.pbiomolbio.2020.02.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Accepted: 02/06/2020] [Indexed: 12/24/2022]
Abstract
Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB), kills more people than any other bacterium. TB control is threatened by the continued spread of drug resistance; multi-drug and extensively drug resistant Mtb require longer, more costly, treatment with multiple drugs causing worse side effects and have a lower likelihood of treatment success. The urgent need for better treatment options for drug resistant Mtb has led the World Health Organization to prioritize development of not only new individual antitubercular agents, but also new drug regimens. This introductory chapter of the special issue Novel insights into TB research and drug discovery within Progress in Biophysics and Molecular Biology, gives a short overview about the general problems of TB and the treatment of this disease today, and introduces the review topics within this issue.
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Affiliation(s)
- Gerhard Grüber
- Nanyang Technological University, School of Biological Sciences, 60 Nanyang Drive, Singapore, 637551, Republic of Singapore.
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20
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Knobloch P, Koliwer-Brandl H, Arnold FM, Hanna N, Gonda I, Adenau S, Personnic N, Barisch C, Seeger MA, Soldati T, Hilbi H. Mycobacterium marinum produces distinct mycobactin and carboxymycobactin siderophores to promote growth in broth and phagocytes. Cell Microbiol 2020; 22:e13163. [PMID: 31945239 DOI: 10.1111/cmi.13163] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Accepted: 12/22/2019] [Indexed: 02/06/2023]
Abstract
Mycobacterium marinum is a model organism for pathogenic Mycobacterium species, including Mycobacterium tuberculosis, the causative agent of tuberculosis. These pathogens enter phagocytes and replicate within the Mycobacterium-containing vacuole, possibly followed by vacuole exit and growth in the host cell cytosol. Mycobacteria release siderophores called mycobactins to scavenge iron, an essential yet poorly soluble and available micronutrient. To investigate the role of M. marinum mycobactins, we purified by organic solvent extraction and identified by mass spectrometry the lipid-bound mycobactin (MBT) and the water-soluble variant carboxymycobactin (cMBT). Moreover, we generated by specialised phage transduction a defined M. marinum ΔmbtB deletion mutant predicted to be defective for mycobactin production. The M. marinum ΔmbtB mutant strain showed a severe growth defect in broth and phagocytes, which was partially complemented by supplying the mbtB gene on a plasmid. Furthermore, purified Fe-MBT or Fe-cMBT improved the growth of wild type as well as ΔmbtB mutant bacteria on minimal plates, but only Fe-cMBT promoted the growth of wild-type M. marinum during phagocyte infection. Finally, the intracellular growth of M. marinum ΔmbtB in Acanthamoeba castellanii amoebae was restored by coinfection with wild-type bacteria. Our study identifies and characterises the M. marinum MBT and cMBT siderophores and reveals the requirement of mycobactins for extra- and intracellular growth of the pathogen.
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Affiliation(s)
- Paulina Knobloch
- Institute of Medical Microbiology, University of Zürich, Zürich, Switzerland
| | | | - Fabian M Arnold
- Institute of Medical Microbiology, University of Zürich, Zürich, Switzerland
| | - Nabil Hanna
- Department of Biochemistry, Faculty of Sciences, University of Geneva, Geneva, Switzerland
| | - Imre Gonda
- Institute of Medical Microbiology, University of Zürich, Zürich, Switzerland
| | - Sophia Adenau
- Institute of Medical Microbiology, University of Zürich, Zürich, Switzerland
| | - Nicolas Personnic
- Institute of Medical Microbiology, University of Zürich, Zürich, Switzerland
| | - Caroline Barisch
- Department of Biochemistry, Faculty of Sciences, University of Geneva, Geneva, Switzerland
| | - Markus A Seeger
- Institute of Medical Microbiology, University of Zürich, Zürich, Switzerland
| | - Thierry Soldati
- Department of Biochemistry, Faculty of Sciences, University of Geneva, Geneva, Switzerland
| | - Hubert Hilbi
- Institute of Medical Microbiology, University of Zürich, Zürich, Switzerland
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21
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Polarly Localized EccE 1 Is Required for ESX-1 Function and Stabilization of ESX-1 Membrane Proteins in Mycobacterium tuberculosis. J Bacteriol 2020; 202:JB.00662-19. [PMID: 31843799 DOI: 10.1128/jb.00662-19] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Accepted: 12/11/2019] [Indexed: 12/15/2022] Open
Abstract
Mycobacterium tuberculosis is a slow-growing intracellular bacterium with the ability to induce host cell death and persist indefinitely in the human body. This pathogen uses the specialized ESX-1 secretion system to secrete virulence factors and potent immunogenic effectors required for disease progression. ESX-1 is a multisubunit apparatus with a membrane complex that is predicted to form a channel in the cytoplasmic membrane. In M. tuberculosis this complex is composed of five membrane proteins: EccB1, EccCa1, EccCb1, EccD1, and EccE1 In this study, we have characterized the membrane component EccE1 and found that deletion of eccE 1 lowers the levels of EccB1, EccCa1, and EccD1, thereby abolishing ESX-1 secretion and attenuating M. tuberculosis ex vivo Surprisingly, secretion of EspB was not affected by loss of EccE1 Furthermore, EccE1 was found to be a membrane- and cell wall-associated protein that needs the presence of other ESX-1 components to assemble into a stable complex at the poles of M. tuberculosis Overall, this investigation provides new insights into the role of EccE1 and its localization in M. tuberculosis IMPORTANCE Tuberculosis (TB), the world's leading cause of death of humans from an infectious disease, is caused by the intracellular bacterium Mycobacterium tuberculosis The development of successful strategies to control TB requires better understanding of the complex interactions between the pathogen and the human host. We investigated the contribution of EccE1, a membrane protein, to the function of the ESX-1 secretion system, the major virulence determinant of M. tuberculosis By combining genetic analysis of selected mutants with eukaryotic cell biology and proteomics, we demonstrate that EccE1 is critical for ESX-1 function, secretion of effector proteins, and pathogenesis. Our research improves knowledge of the molecular basis of M. tuberculosis virulence and enhances our understanding of pathogenesis.
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22
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Ates LS. New insights into the mycobacterial PE and PPE proteins provide a framework for future research. Mol Microbiol 2020; 113:4-21. [PMID: 31661176 PMCID: PMC7028111 DOI: 10.1111/mmi.14409] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/25/2019] [Indexed: 12/30/2022]
Abstract
The PE and PPE proteins of Mycobacterium tuberculosis have been studied with great interest since their discovery. Named after the conserved proline (P) and glutamic acid (E) residues in their N-terminal domains, these proteins are postulated to perform wide-ranging roles in virulence and immune modulation. However, technical challenges in studying these proteins and their encoding genes have hampered the elucidation of molecular mechanisms and leave many open questions regarding the biological functions mediated by these proteins. Here, I review the shared and unique characteristics of PE and PPE proteins from a molecular perspective linking this information to their functions in mycobacterial virulence. I discuss how the different subgroups (PE_PGRS, PPE-PPW, PPE-SVP and PPE-MPTR) are defined and why this classification of paramount importance to understand the PE and PPE proteins as individuals and or groups. The goal of this MicroReview is to summarize and structure the existing information on this gene family into a simplified framework of thinking about PE and PPE proteins and genes. Thereby, I hope to provide helpful starting points in studying these genes and proteins for researchers with different backgrounds. This has particular implications for the design and monitoring of novel vaccine candidates and in understanding the evolution of the M. tuberculosis complex.
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Affiliation(s)
- Louis S. Ates
- Department of Experimental ImmunologyAmsterdam Infection & Immunity InstituteAmsterdam UMCUniversity of AmsterdamMeibergdreef 9Amsterdamthe Netherlands
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23
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Poweleit N, Czudnochowski N, Nakagawa R, Trinidad DD, Murphy KC, Sassetti CM, Rosenberg OS. The structure of the endogenous ESX-3 secretion system. eLife 2019; 8:52983. [PMID: 31886769 PMCID: PMC6986878 DOI: 10.7554/elife.52983] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Accepted: 12/30/2019] [Indexed: 12/15/2022] Open
Abstract
The ESX (or Type VII) secretion systems are protein export systems in mycobacteria and many Gram-positive bacteria that mediate a broad range of functions including virulence, conjugation, and metabolic regulation. These systems translocate folded dimers of WXG100-superfamily protein substrates across the cytoplasmic membrane. We report the cryo-electron microscopy structure of an ESX-3 system, purified using an epitope tag inserted with recombineering into the chromosome of the model organism Mycobacterium smegmatis. The structure reveals a stacked architecture that extends above and below the inner membrane of the bacterium. The ESX-3 protomer complex is assembled from a single copy of the EccB3, EccC3, and EccE3 and two copies of the EccD3 protein. In the structure, the protomers form a stable dimer that is consistent with assembly into a larger oligomer. The ESX-3 structure provides a framework for further study of these important bacterial transporters.
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Affiliation(s)
- Nicole Poweleit
- Department of Medicine, Division of Infectious Diseases, University of California, San Francisco, San Francisco, United States.,Chan-Zuckerberg Biohub, University of California, San Francisco, San Francisco, United States
| | - Nadine Czudnochowski
- Department of Medicine, Division of Infectious Diseases, University of California, San Francisco, San Francisco, United States.,Chan-Zuckerberg Biohub, University of California, San Francisco, San Francisco, United States
| | - Rachel Nakagawa
- Department of Medicine, Division of Infectious Diseases, University of California, San Francisco, San Francisco, United States
| | - Donovan D Trinidad
- Department of Medicine, Division of Infectious Diseases, University of California, San Francisco, San Francisco, United States.,Chan-Zuckerberg Biohub, University of California, San Francisco, San Francisco, United States
| | - Kenan C Murphy
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, United States
| | - Christopher M Sassetti
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, United States
| | - Oren S Rosenberg
- Department of Medicine, Division of Infectious Diseases, University of California, San Francisco, San Francisco, United States.,Chan-Zuckerberg Biohub, University of California, San Francisco, San Francisco, United States
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24
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Famelis N, Rivera-Calzada A, Degliesposti G, Wingender M, Mietrach N, Skehel JM, Fernandez-Leiro R, Böttcher B, Schlosser A, Llorca O, Geibel S. Architecture of the mycobacterial type VII secretion system. Nature 2019; 576:321-325. [PMID: 31597161 DOI: 10.1038/s41586-019-1633-1] [Citation(s) in RCA: 68] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2018] [Accepted: 09/06/2019] [Indexed: 11/09/2022]
Abstract
Host infection by pathogenic mycobacteria, such as Mycobacterium tuberculosis, is facilitated by virulence factors that are secreted by type VII secretion systems1. A molecular understanding of the type VII secretion mechanism has been hampered owing to a lack of three-dimensional structures of the fully assembled secretion apparatus. Here we report the cryo-electron microscopy structure of a membrane-embedded core complex of the ESX-3/type VII secretion system from Mycobacterium smegmatis. The core of the ESX-3 secretion machine consists of four protein components-EccB3, EccC3, EccD3 and EccE3, in a 1:1:2:1 stoichiometry-which form two identical protomers. The EccC3 coupling protein comprises a flexible array of four ATPase domains, which are linked to the membrane through a stalk domain. The domain of unknown function (DUF) adjacent to the stalk is identified as an ATPase domain that is essential for secretion. EccB3 is predominantly periplasmatic, but a small segment crosses the membrane and contacts the stalk domain. This suggests that conformational changes in the stalk domain-triggered by substrate binding at the distal end of EccC3 and subsequent ATP hydrolysis in the DUF-could be coupled to substrate secretion to the periplasm. Our results reveal that the architecture of type VII secretion systems differs markedly from that of other known secretion machines2, and provide a structural understanding of these systems that will be useful for the design of antimicrobial strategies that target bacterial virulence.
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Affiliation(s)
- Nikolaos Famelis
- Institute for Molecular Infection Biology, Julius-Maximilians-University Würzburg, Würzburg, Germany.,Rudolf Virchow Center for Experimental Biomedicine, Julius-Maximilians-University Würzburg, Würzburg, Germany
| | - Angel Rivera-Calzada
- Structural Biology Programme, Spanish National Cancer Research Centre (CNIO), Madrid, Spain
| | | | - Maria Wingender
- Institute for Molecular Infection Biology, Julius-Maximilians-University Würzburg, Würzburg, Germany.,Rudolf Virchow Center for Experimental Biomedicine, Julius-Maximilians-University Würzburg, Würzburg, Germany
| | - Nicole Mietrach
- Institute for Molecular Infection Biology, Julius-Maximilians-University Würzburg, Würzburg, Germany.,Rudolf Virchow Center for Experimental Biomedicine, Julius-Maximilians-University Würzburg, Würzburg, Germany
| | | | - Rafael Fernandez-Leiro
- Structural Biology Programme, Spanish National Cancer Research Centre (CNIO), Madrid, Spain
| | - Bettina Böttcher
- Rudolf Virchow Center for Experimental Biomedicine, Julius-Maximilians-University Würzburg, Würzburg, Germany.,Rudolf Virchow Center for Experimental Biomedicine, Electron Microscopy Facility, Julius-Maximilians-University Würzburg, Würzburg, Germany
| | - Andreas Schlosser
- Rudolf Virchow Center for Experimental Biomedicine, Julius-Maximilians-University Würzburg, Würzburg, Germany
| | - Oscar Llorca
- Structural Biology Programme, Spanish National Cancer Research Centre (CNIO), Madrid, Spain.
| | - Sebastian Geibel
- Institute for Molecular Infection Biology, Julius-Maximilians-University Würzburg, Würzburg, Germany. .,Rudolf Virchow Center for Experimental Biomedicine, Julius-Maximilians-University Würzburg, Würzburg, Germany.
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25
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Dragset MS, Ioerger TR, Zhang YJ, Mærk M, Ginbot Z, Sacchettini JC, Flo TH, Rubin EJ, Steigedal M. Genome-wide Phenotypic Profiling Identifies and Categorizes Genes Required for Mycobacterial Low Iron Fitness. Sci Rep 2019; 9:11394. [PMID: 31388080 PMCID: PMC6684656 DOI: 10.1038/s41598-019-47905-y] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 07/18/2019] [Indexed: 11/26/2022] Open
Abstract
Iron is vital for nearly all living organisms, but during infection, not readily available to pathogens. Infectious bacteria therefore depend on specialized mechanisms to survive when iron is limited. These mechanisms make attractive targets for new drugs. Here, by genome-wide phenotypic profiling, we identify and categorize mycobacterial genes required for low iron fitness. Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB), can scavenge host-sequestered iron by high-affinity iron chelators called siderophores. We take advantage of siderophore redundancy within the non-pathogenic mycobacterial model organism M. smegmatis (Msmeg), to identify genes required for siderophore dependent and independent fitness when iron is low. In addition to genes with a potential function in recognition, transport or utilization of mycobacterial siderophores, we identify novel putative low iron survival strategies that are separate from siderophore systems. We also identify the Msmeg in vitro essential gene set, and find that 96% of all growth-required Msmeg genes have a mutual ortholog in Mtb. Of these again, nearly 90% are defined as required for growth in Mtb as well. Finally, we show that a novel, putative ferric iron ABC transporter contributes to low iron fitness in Msmeg, in a siderophore independent manner.
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Affiliation(s)
- Marte S Dragset
- NTNU Norwegian University of Science and Technology, Centre of Molecular Inflammation Research and Department of Clinical and Molecular Medicine, Trondheim, 7491, Norway. .,Harvard T.H. Chan School of Public Health, Department of Immunology and Infectious Diseases, Boston, MA, 02115, USA. .,Germans Trias i Pujol Research Institute, Tuberculosis Research Unit, Badalona, 80916, Spain.
| | - Thomas R Ioerger
- Texas A&M University, Department of Computer Science, College Station, TX, 77843, USA
| | - Yanjia J Zhang
- Harvard T.H. Chan School of Public Health, Department of Immunology and Infectious Diseases, Boston, MA, 02115, USA
| | - Mali Mærk
- NTNU Norwegian University of Science and Technology, Centre of Molecular Inflammation Research and Department of Clinical and Molecular Medicine, Trondheim, 7491, Norway
| | - Zekarias Ginbot
- NTNU Norwegian University of Science and Technology, Centre of Molecular Inflammation Research and Department of Clinical and Molecular Medicine, Trondheim, 7491, Norway
| | - James C Sacchettini
- Texas A&M University, Department of Biochemistry and Biophysics, College Station, TX, 77843, USA
| | - Trude H Flo
- NTNU Norwegian University of Science and Technology, Centre of Molecular Inflammation Research and Department of Clinical and Molecular Medicine, Trondheim, 7491, Norway
| | - Eric J Rubin
- Harvard T.H. Chan School of Public Health, Department of Immunology and Infectious Diseases, Boston, MA, 02115, USA
| | - Magnus Steigedal
- NTNU Norwegian University of Science and Technology, Centre of Molecular Inflammation Research and Department of Clinical and Molecular Medicine, Trondheim, 7491, Norway.,Harvard T.H. Chan School of Public Health, Department of Immunology and Infectious Diseases, Boston, MA, 02115, USA.,St. Olavs University Hospital, Department of Medical Microbiology, Trondheim, 7030, Norway
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26
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Madacki J, Mas Fiol G, Brosch R. Update on the virulence factors of the obligate pathogen Mycobacterium tuberculosis and related tuberculosis-causing mycobacteria. INFECTION GENETICS AND EVOLUTION 2019; 72:67-77. [DOI: 10.1016/j.meegid.2018.12.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 12/02/2018] [Accepted: 12/07/2018] [Indexed: 12/21/2022]
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27
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Vaziri F, Brosch R. ESX/Type VII Secretion Systems-An Important Way Out for Mycobacterial Proteins. Microbiol Spectr 2019; 7:10.1128/microbiolspec.psib-0029-2019. [PMID: 31298207 PMCID: PMC10957191 DOI: 10.1128/microbiolspec.psib-0029-2019] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Indexed: 11/20/2022] Open
Abstract
The causative agent of human tuberculosis, Mycobacterium tuberculosis, has a complex lipid-rich diderm envelope, which acts as a major barrier protecting the bacterium against the hostile environment inside the host cells. For the transfer of diverse molecules across this complex cell envelope, M. tuberculosis has a series of general and specialized protein secretion systems, characterized by the SecA general secretion pathway, the twin-arginine translocation pathway, and five specific ESX type VII secretion systems. In this review, we focus on the latter systems, known as ESX-1 to ESX-5, which were first discovered almost 20 years ago during the in silico analysis of the genome sequence of M. tuberculosis H37Rv. Since then, these systems have been the subject of highly dynamic research due to their involvement in several key biological processes and host-pathogen interactions of the tubercle bacilli.
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Affiliation(s)
- Farzam Vaziri
- Institut Pasteur, Unit for Integrated Mycobacterial Pathogenomics, UMR3525 CNRS, 75015 Paris, France
- Department of Mycobacteriology and Pulmonary Research, Pasteur Institute of Iran, 13164 Tehran, Iran
- Microbiology Research Center, Pasteur Institute of Iran, 13164 Tehran, Iran
| | - Roland Brosch
- Institut Pasteur, Unit for Integrated Mycobacterial Pathogenomics, UMR3525 CNRS, 75015 Paris, France
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28
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van Winden VJC, Houben ENG, Braunstein M. Protein Export into and across the Atypical Diderm Cell Envelope of Mycobacteria. Microbiol Spectr 2019; 7:10.1128/microbiolspec.gpp3-0043-2018. [PMID: 31400094 PMCID: PMC10957183 DOI: 10.1128/microbiolspec.gpp3-0043-2018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Indexed: 02/07/2023] Open
Abstract
Mycobacteria, including the infamous pathogen Mycobacterium tuberculosis, are high-GC Gram-positive bacteria with a distinctive cell envelope. Although there is a typical inner membrane, the mycobacterial cell envelope is unusual in having its peptidoglycan layer connected to a polymer of arabinogalactan, which in turn is covalently attached to long-chain mycolic acids that help form a highly impermeable mycobacterial outer membrane. This complex double-membrane, or diderm, cell envelope imparts mycobacteria with unique requirements for protein export into and across the cell envelope for secretion into the extracellular environment. In this article, we review the four protein export pathways known to exist in mycobacteria: two conserved systems that exist in all types of bacteria (the Sec and Tat pathways) and two specialized systems that exist in mycobacteria, corynebacteria, and a subset of low-GC Gram-positive bacteria (the SecA2 and type VII secretion pathways). We describe the progress made over the past 15 years in understanding each of these mycobacterial export pathways, and we highlight the need for research to understand the specific steps of protein export across the mycobacterial outer membrane.
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Affiliation(s)
- Vincent J C van Winden
- Department of Medical Microbiology and Infection Control, Amsterdam UMC, Vrije Universiteit, Amsterdam, The Netherlands
| | - Edith N G Houben
- Section of Molecular Microbiology, Amsterdam Institute for Molecules, Medicines, and Systems, Vrije Universiteit, Amsterdam, The Netherlands
| | - Miriam Braunstein
- Department of Microbiology and Immunology, University of North Carolina-Chapel Hill, Chapel Hill, NC 27599
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29
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A New ESX-1 Substrate in Mycobacterium marinum That Is Required for Hemolysis but Not Host Cell Lysis. J Bacteriol 2019; 201:JB.00760-18. [PMID: 30833360 DOI: 10.1128/jb.00760-18] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2018] [Accepted: 02/28/2019] [Indexed: 02/07/2023] Open
Abstract
The ESX-1 (ESAT-6 system 1) secretion system plays a conserved role in the virulence of diverse mycobacterial pathogens, including the human pathogen Mycobacterium tuberculosis and M. marinum, an environmental mycobacterial species. The ESX-1 system promotes the secretion of protein virulence factors to the extracytoplasmic environment. The secretion of these proteins triggers the host response by lysing the phagosome during macrophage infection. Using proteomic analyses of the M. marinum secretome in the presence and absence of a functional ESX-1 system, we and others have hypothesized that MMAR_2894, a PE family protein, is a potential ESX-1 substrate in M. marinum We used genetic and quantitative proteomic approaches to determine if MMAR_2894 is secreted by the ESX-1 system, and we defined the requirement of MMAR_2894 for ESX-1-mediated secretion and virulence. We show that MMAR_2894 is secreted by the ESX-1 system in M. marinum and is itself required for the optimal secretion of the known ESX-1 substrates in M. marinum Moreover, we found that MMAR_2894 was differentially required for hemolysis and cytolysis of macrophages, two lytic activities ascribed to the M. marinum ESX-1 system.IMPORTANCE Both Mycobacterium tuberculosis, the cause of human tuberculosis (TB), and Mycobacterium marinum, a pathogen of ectotherms, use the ESX-1 secretion system to cause disease. There are many established similarities between the ESX-1 systems in M. tuberculosis and in M. marinum Yet the two bacteria infect different hosts, hinting at species-specific functions of the ESX-1 system. Our findings demonstrate that MMAR_2894 is a PE protein secreted by the ESX-1 system of M. marinum We show that MMAR_2894 is required for the optimal secretion of mycobacterial proteins required for disease. Because the MMAR_2894 gene is not conserved in M. tuberculosis, our findings demonstrate that MMAR_2894 may contribute to a species-specific function of the ESX-1 system in M. marinum, providing new insight into how the M. marinum and M. tuberculosis systems differ.
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30
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Saelens JW, Viswanathan G, Tobin DM. Mycobacterial Evolution Intersects With Host Tolerance. Front Immunol 2019; 10:528. [PMID: 30967867 PMCID: PMC6438904 DOI: 10.3389/fimmu.2019.00528] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Accepted: 02/27/2019] [Indexed: 12/12/2022] Open
Abstract
Over the past 200 years, tuberculosis (TB) has caused more deaths than any other infectious disease, likely infecting more people than it has at any other time in human history. Mycobacterium tuberculosis (Mtb), the etiologic agent of TB, is an obligate human pathogen that has evolved through the millennia to become an archetypal human-adapted pathogen. This review focuses on the evolutionary framework by which Mtb emerged as a specialized human pathogen and applies this perspective to the emergence of specific lineages that drive global TB burden. We consider how evolutionary pressures, including transmission dynamics, host tolerance, and human population patterns, may have shaped the evolution of diverse mycobacterial genomes.
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Affiliation(s)
- Joseph W. Saelens
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, NC, United States
| | - Gopinath Viswanathan
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, NC, United States
| | - David M. Tobin
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, NC, United States
- Department of Immunology, Duke University School of Medicine, Durham, NC, United States
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31
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Mycobacterium tuberculosis Type VII Secretion System Effectors Differentially Impact the ESCRT Endomembrane Damage Response. mBio 2018; 9:mBio.01765-18. [PMID: 30482832 PMCID: PMC6282207 DOI: 10.1128/mbio.01765-18] [Citation(s) in RCA: 64] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Intracellular pathogens have varied strategies to breach the endolysosomal barrier so that they can deliver effectors to the host cytosol, access nutrients, replicate in the cytoplasm, and avoid degradation in the lysosome. In the case of Mycobacterium tuberculosis, the bacterium perforates the phagosomal membrane shortly after being taken up by macrophages. Phagosomal damage depends upon the mycobacterial ESX-1 type VII secretion system (T7SS). Sterile insults, such as silica crystals or membranolytic peptides, can also disrupt phagosomal and endolysosomal membranes. Recent work revealed that the host endosomal sorting complex required for transport (ESCRT) machinery rapidly responds to sterile endolysosomal damage and promotes membrane repair. We hypothesized that ESCRTs might also respond to pathogen-induced phagosomal damage and that M. tuberculosis could impair this host response. Indeed, we found that ESCRT-III proteins were recruited to M. tuberculosis phagosomes in an ESX-1-dependent manner. We previously demonstrated that the mycobacterial effectors EsxG/TB9.8 and EsxH/TB10.4, both secreted by the ESX-3 T7SS, can inhibit ESCRT-dependent trafficking of receptors to the lysosome. Here, we additionally show that ESCRT-III recruitment to sites of endolysosomal damage is antagonized by EsxG and EsxH, both within the context of M. tuberculosis infection and sterile injury. Moreover, EsxG and EsxH themselves respond within minutes to membrane damage in a manner that is independent of calcium and ESCRT-III recruitment. Thus, our study reveals that T7SS effectors and ESCRT participate in a series of measures and countermeasures for control of phagosome integrity.IMPORTANCE Mycobacterium tuberculosis causes tuberculosis, which kills more people than any other infection. M. tuberculosis grows in macrophages, cells that specialize in engulfing and degrading microorganisms. Like many intracellular pathogens, in order to cause disease, M. tuberculosis damages the membrane-bound compartment (phagosome) in which it is enclosed after macrophage uptake. Recent work showed that when chemicals damage this type of intracellular compartment, cells rapidly detect and repair the damage, using machinery called the endosomal sorting complex required for transport (ESCRT). Therefore, we hypothesized that ESCRT might also respond to pathogen-induced damage. At the same time, our previous work showed that the EsxG-EsxH heterodimer of M. tuberculosis can inhibit ESCRT, raising the possibility that M. tuberculosis impairs this host response. Here, we show that ESCRT is recruited to damaged M. tuberculosis phagosomes and that EsxG-EsxH undermines ESCRT-mediated endomembrane repair. Thus, our studies demonstrate a battle between host and pathogen over endomembrane integrity.
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32
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Chao A, Sieminski PJ, Owens CP, Goulding CW. Iron Acquisition in Mycobacterium tuberculosis. Chem Rev 2018; 119:1193-1220. [PMID: 30474981 DOI: 10.1021/acs.chemrev.8b00285] [Citation(s) in RCA: 71] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The highly contagious disease tuberculosis (TB) is caused by the bacterium Mycobacterium tuberculosis (Mtb), which has been evolving drug resistance at an alarming rate. Like all human pathogens, Mtb requires iron for growth and virulence. Consequently, Mtb iron transport is an emerging drug target. However, the development of anti-TB drugs aimed at these metabolic pathways has been restricted by the dearth of information on Mtb iron acquisition. In this Review, we describe the multiple strategies utilized by Mtb to acquire ferric iron and heme iron. Mtb iron uptake is a complex process, requiring biosynthesis and subsequent export of Mtb siderophores, followed by ferric iron scavenging and ferric-siderophore import into Mtb. Additionally, Mtb possesses two possible heme uptake pathways and an Mtb-specific mechanism of heme degradation that yields iron and novel heme-degradation products. We conclude with perspectives for potential therapeutics that could directly target Mtb heme and iron uptake machineries. We also highlight how hijacking Mtb heme and iron acquisition pathways for drug import may facilitate drug transport through the notoriously impregnable Mtb cell wall.
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Affiliation(s)
| | | | - Cedric P Owens
- Schmid College of Science and Technology , Chapman University , Orange , California 92866 , United States
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33
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Nath Y, Ray SK, Buragohain AK. Essential role of the ESX-3 associated eccD3 locus in maintaining the cell wall integrity of Mycobacterium smegmatis. Int J Med Microbiol 2018; 308:784-795. [PMID: 30257807 DOI: 10.1016/j.ijmm.2018.06.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 05/21/2018] [Accepted: 06/24/2018] [Indexed: 11/28/2022] Open
Abstract
Mycobacterial pathogens have evolved a unique secretory apparatus called the Type VII secretion system (T7SS) which comprises of five gene clusters designated as ESX1, ESX2, ESX3, ESX4, and ESX5. Of these the ESX3 T7SS plays an important role in the regulatory uptake of iron from the environment, thereby enabling the bacteria to establish successful infection in the host. However, ESX3 secretion system is conserved among all the mycobacterial species including the fast-growing nonpathogenic species M. smegmatis. Although the function of ESX3 T7SS is known to be absolutely critical for establishing infection by M. tuberculosis, its conserved nature in all the pathogenic and nonpathogenic mycobacterial species intrigues to explore the additional functional roles in Mycobacterium species through which potent targets for drugs can be identified and developed. In the present study, we investigated the possible role of EccD3, a transmembrane protein of the ESX3 T7SS in M. smegmatis by deleting the entire eccD3 gene by efficient allelic exchange method. The preliminary investigations through the creation of knockout mutant of the eccD3 gene indicate that this secretory apparatus has an important role in maintaining the cell wall integrity which was evident from the abnormal colony morphology, lack of biofilm formation and difference in cell wall permeability.
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Affiliation(s)
- Yutika Nath
- Department of Molecular Biology and Biotechnology, Tezpur University, Napaam, Tezpur, Assam, 784028, India.
| | - Suvendra Kumar Ray
- Department of Molecular Biology and Biotechnology, Tezpur University, Napaam, Tezpur, Assam, 784028, India.
| | - Alak Kumar Buragohain
- Department of Molecular Biology and Biotechnology, Tezpur University, Napaam, Tezpur, Assam, 784028, India; Dibrugarh University, Dibrugarh, Assam, 786004, India.
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34
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Patel K, Butala S, Khan T, Suvarna V, Sherje A, Dravyakar B. Mycobacterial siderophore: A review on chemistry and biology of siderophore and its potential as a target for tuberculosis. Eur J Med Chem 2018; 157:783-790. [PMID: 30142615 DOI: 10.1016/j.ejmech.2018.08.030] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2018] [Revised: 08/09/2018] [Accepted: 08/10/2018] [Indexed: 10/28/2022]
Abstract
Mycobacterium tuberculosis (MTB), the causative agent of tuberculosis is known to secrete low molecular mass compounds called siderophores especially under low iron conditions to chelate iron from host environment. Iron is essential for growth and other essential processes to sustain life of the bacterium in the host. Hence targeting siderophore is considered to be an alternative approach to prevent further virulence of bacterium into the host. This review article presents classification of siderophores, their role in transporting iron into the tubercular cell, biosynthesis of mycobactins, viability of siderophore as a therapeutic target and also focuses on overview on various approaches to target siderophore. The approaches encompass mutation effect on genes involved in siderophore recycling, synthetic as well as natural compounds that can inhibit further spread of bacterium by targeting siderophore.
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Affiliation(s)
- Kavitkumar Patel
- Department of Pharmaceutical Chemistry, SVKM'S Dr. Bhanuben Nanavati College of Pharmacy, Vile Parle (W), Mumbai, 400 056, India.
| | - Sahil Butala
- Department of Pharmaceutical Chemistry, SVKM'S Dr. Bhanuben Nanavati College of Pharmacy, Vile Parle (W), Mumbai, 400 056, India
| | - Tabassum Khan
- Department of Pharmaceutical Chemistry, SVKM'S Dr. Bhanuben Nanavati College of Pharmacy, Vile Parle (W), Mumbai, 400 056, India
| | - Vasanti Suvarna
- Department of Pharmaceutical Chemistry, SVKM'S Dr. Bhanuben Nanavati College of Pharmacy, Vile Parle (W), Mumbai, 400 056, India
| | - Atul Sherje
- Department of Pharmaceutical Chemistry, SVKM'S Dr. Bhanuben Nanavati College of Pharmacy, Vile Parle (W), Mumbai, 400 056, India
| | - Bhushan Dravyakar
- Department of Pharmaceutical Chemistry, SVKM'S Dr. Bhanuben Nanavati College of Pharmacy, Vile Parle (W), Mumbai, 400 056, India
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Esx Paralogs Are Functionally Equivalent to ESX-1 Proteins but Are Dispensable for Virulence in Mycobacterium marinum. J Bacteriol 2018; 200:JB.00726-17. [PMID: 29555701 DOI: 10.1128/jb.00726-17] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Accepted: 03/11/2018] [Indexed: 12/20/2022] Open
Abstract
Mycobacterium marinum is a nontuberculous pathogen of poikilothermic fish and an opportunistic human pathogen. Like tuberculous mycobacteria, the M. marinum M strain requires the ESX-1 (ESAT-6 system 1) secretion system for virulence in host cells. EsxB and EsxA, two major virulence factors exported by the ESX-1 system, are encoded by the esxBA genes within the ESX-1 locus. Deletion of the esxBA genes abrogates ESX-1 export and attenuates M. marinum in ex vivo and in vivo models of infection. Interestingly, there are several duplications of the esxB and esxA genes (esxB_1, esxB_2, esxA_1, esxA_2, and esxA_3) in the M. marinum M genome located outside the ESX-1 locus. We sought to understand if this region, known as ESX-6, contributes to ESX-1-mediated virulence. We found that deletion of the esxB_1 gene alone or the entire ESX-6 locus did not impact ESX-1 export or function, supporting the idea that the esxBA genes present at the ESX-1 locus are the primary contributors to ESX-1-mediated virulence. Nevertheless, overexpression of the esxB_1 locus complemented ESX-1 function in the ΔesxBA strain, signifying that the two loci are functionally equivalent. Our findings raise questions about why duplicate versions of the esxBA genes are maintained in the M. marinum M genome and how these proteins, which are functionally equivalent to virulence factors, contribute to mycobacterial biology.IMPORTANCEMycobacterium tuberculosis is the causative agent of the human disease tuberculosis (TB). There are 10.4 million cases and 1.7 million TB-associated deaths annually, making TB a leading cause of death globally. Nontuberculous mycobacteria (NTM) cause chronic human infections that are acquired from the environment. Despite differences in disease etiology, both tuberculous and NTM pathogens use the ESX-1 secretion system to cause disease. The nontubercular mycobacterial species, Mycobacterium marinum, has additional copies of specific ESX-1 genes. Our findings demonstrate that the duplicated genes do not contribute to virulence but can substitute for virulence factors in M. marinum These findings suggest that the duplicated genes may play a specific role in NTM biology.
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Cardenal-Muñoz E, Barisch C, Lefrançois LH, López-Jiménez AT, Soldati T. When Dicty Met Myco, a (Not So) Romantic Story about One Amoeba and Its Intracellular Pathogen. Front Cell Infect Microbiol 2018; 7:529. [PMID: 29376033 PMCID: PMC5767268 DOI: 10.3389/fcimb.2017.00529] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2017] [Accepted: 12/18/2017] [Indexed: 01/06/2023] Open
Abstract
In recent years, Dictyostelium discoideum has become an important model organism to study the cell biology of professional phagocytes. This amoeba not only shares many molecular features with mammalian macrophages, but most of its fundamental signal transduction pathways are conserved in humans. The broad range of existing genetic and biochemical tools, together with its suitability for cell culture and live microscopy, make D. discoideum an ideal and versatile laboratory organism. In this review, we focus on the use of D. discoideum as a phagocyte model for the study of mycobacterial infections, in particular Mycobacterium marinum. We look in detail at the intracellular cycle of M. marinum, from its uptake by D. discoideum to its active or passive egress into the extracellular medium. In addition, we describe the molecular mechanisms that both the mycobacterial invader and the amoeboid host have developed to fight against each other, and compare and contrast with those developed by mammalian phagocytes. Finally, we introduce the methods and specific tools that have been used so far to monitor the D. discoideum-M. marinum interaction.
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Affiliation(s)
- Elena Cardenal-Muñoz
- Department of Biochemistry, Sciences II, Faculty of Sciences, University of Geneva, Geneva, Switzerland
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WhiB6 regulation of ESX-1 gene expression is controlled by a negative feedback loop in Mycobacterium marinum. Proc Natl Acad Sci U S A 2017; 114:E10772-E10781. [PMID: 29180415 DOI: 10.1073/pnas.1710167114] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
ESX (ESAT-6 system) export systems play diverse roles across mycobacterial species. Interestingly, genetic disruption of ESX systems in different species does not result in an accumulation of protein substrates in the mycobacterial cell. However, the mechanisms underlying this observation are elusive. We hypothesized that the levels of ESX substrates were regulated by a feedback-control mechanism, linking the levels of substrates to the secretory status of ESX systems. To test this hypothesis, we used a combination of genetic, transcriptomic, and proteomic approaches to define export-dependent mechanisms regulating the levels of ESX-1 substrates in Mycobacterium marinum WhiB6 is a transcription factor that regulates expression of genes encoding ESX-1 substrates. We found that, in the absence of the genes encoding conserved membrane components of the ESX-1 system, the expression of the whiB6 gene and genes encoding ESX-1 substrates were reduced. Accordingly, the levels of ESX-1 substrates were decreased, and WhiB6 was not detected in M. marinum strains lacking genes encoding ESX-1 components. We demonstrated that, in the absence of EccCb1, a conserved ESX-1 component, substrate gene expression was restored by constitutive, but not native, expression of the whiB6 gene. Finally, we found that the loss of WhiB6 resulted in a virulent M. marinum strain with reduced ESX-1 secretion. Together, our findings demonstrate that the levels of ESX-1 substrates in M. marinum are fine-tuned by negative feedback control, linking the expression of the whiB6 gene to the presence, not the functionality, of the ESX-1 membrane complex.
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Uribe-Querol E, Rosales C. Control of Phagocytosis by Microbial Pathogens. Front Immunol 2017; 8:1368. [PMID: 29114249 PMCID: PMC5660709 DOI: 10.3389/fimmu.2017.01368] [Citation(s) in RCA: 141] [Impact Index Per Article: 20.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2017] [Accepted: 10/05/2017] [Indexed: 12/17/2022] Open
Abstract
Phagocytosis is a fundamental process of cells to capture and ingest foreign particles. Small unicellular organisms such as free-living amoeba use this process to acquire food. In pluricellular organisms, phagocytosis is a universal phenomenon that all cells are able to perform (including epithelial, endothelial, fibroblasts, etc.), but some specialized cells (such as neutrophils and macrophages) perform this very efficiently and were therefore named professional phagocytes by Rabinovitch. Cells use phagocytosis to capture and clear all particles larger than 0.5 µm, including pathogenic microorganisms and cellular debris. Phagocytosis involves a series of steps from recognition of the target particle, ingestion of it in a phagosome (phagocytic vacuole), maturation of this phagosome into a phagolysosome, to the final destruction of the ingested particle in the robust antimicrobial environment of the phagolysosome. For the most part, phagocytosis is an efficient process that eliminates invading pathogens and helps maintaining homeostasis. However, several pathogens have also evolved different strategies to prevent phagocytosis from proceeding in a normal way. These pathogens have a clear advantage to perpetuate the infection and continue their replication. Here, we present an overview of the phagocytic process with emphasis on the antimicrobial elements professional phagocytes use. We also summarize the current knowledge on the microbial strategies different pathogens use to prevent phagocytosis either at the level of ingestion, phagosome formation, and maturation, and even complete escape from phagosomes.
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Affiliation(s)
- Eileen Uribe-Querol
- División de Estudios de Posgrado e Investigación, Facultad de Odontología, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Carlos Rosales
- Departamento de Inmunología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico
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Fang Z, Newton-Foot M, Sampson SL, Gey van Pittius NC. Two promoters in the esx-3 gene cluster of Mycobacterium smegmatis respond inversely to different iron concentrations in vitro. BMC Res Notes 2017; 10:426. [PMID: 28841831 PMCID: PMC6389172 DOI: 10.1186/s13104-017-2752-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 08/23/2017] [Indexed: 11/20/2022] Open
Abstract
Background The ESX secretion system, also known as the Type VII secretion system, is mostly found in mycobacteria and plays important roles in nutrient acquisition and host pathogenicity. One of the five ESXs, ESX-3, is associated with mycobactin-mediated iron acquisition. Although the functions of some of the membrane-associated components of the ESX systems have been described, the role of by mycosin-3 remains elusive. The esx-3 gene cluster encoding ESX-3 in both Mycobacterium tuberculosis and Mycobacterium smegmatis has two promoters, suggesting the presence of two transcriptional units. Previous studies indicated that the two promoters only showed a difference in response under acid stress (pH 4.2). This study aimed to study the effect of a mycosin-3 deletion on the physiology of M. smegmatis and to assess the promoter activities in wildtype, mycosin-3 mutant and complementation strains. Results The gene mycP3 was deleted from wildtype M. smegmatis via homologous recombination. The mycP3 gene was complemented in the deletion mutant using each of the two intrinsic promoters from the M. smegmatis esx-3 gene cluster. The four strains were compared in term of bacterial growth and intracellular iron content. The two promoter activities were assessed under iron-rich, iron-deprived and iron-rescued conditions by assessing the mycP3 expression level. Although the mycP3 gene deletion did not significantly impact bacterial growth or intracellular iron levels in comparison to the wild-type and complemented strains, the two esx-3 promoters were shown to respond inversely to iron deprivation and iron rescue. Conclusion This finding correlates with the previously published data that the first promoter upstream of msmeg0615, is upregulated under low iron levels but downregulated under high iron levels. In addition, the second promoter, upstream of msmeg0620, behaves in an inverse fashion to the first promoter implying that the genes downstream may have additional roles when the iron levels are high. Electronic supplementary material The online version of this article (doi:10.1186/s13104-017-2752-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Zhuo Fang
- DST/NRF Centre of Excellence in Biomedical Tuberculosis Research, US/MRC Centre for Molecular and Cellular Biology, Division of Molecular Biology and Human Genetics, Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, University of Stellenbosch, Francie van Zijl Drive, Tygerberg, 7505, South Africa.
| | - Mae Newton-Foot
- Division of Medical Microbiology, Department of Pathology, Faculty of Medicine and Health Sciences, University of Stellenbosch, Tygerberg, South Africa.,National Health Laboratory Services, Tygerberg Hospital, Francie van Zijl Drive, Tygerberg, 7505, South Africa
| | - Samantha Leigh Sampson
- DST/NRF Centre of Excellence in Biomedical Tuberculosis Research, US/MRC Centre for Molecular and Cellular Biology, Division of Molecular Biology and Human Genetics, Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, University of Stellenbosch, Francie van Zijl Drive, Tygerberg, 7505, South Africa
| | - Nicolaas Claudius Gey van Pittius
- DST/NRF Centre of Excellence in Biomedical Tuberculosis Research, US/MRC Centre for Molecular and Cellular Biology, Division of Molecular Biology and Human Genetics, Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, University of Stellenbosch, Francie van Zijl Drive, Tygerberg, 7505, South Africa
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Abstract
Mycobacterial 6-kDa early secreted antigenic target (ESAT-6) system (ESX) exporters transport proteins across the cytoplasmic membrane. Many proteins transported by ESX systems are then translocated across the mycobacterial cell envelope and secreted from the cell. Although the mechanism underlying protein transport across the mycolate outer membrane remains elusive, the ESX systems are closely connected with and localize to the cell envelope. Links between ESX-associated proteins, cell wall synthesis, and the maintenance of cell envelope integrity have been reported. Genes encoding the ESX systems and those required for biosynthesis of the mycobacterial envelope are coregulated. Here, we review the interplay between ESX systems and the mycobacterial cell envelope.
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Xiang ZH, Sun RF, Lin C, Chen FZ, Mai JT, Liu YX, Xu ZY, Zhang L, Liu J. Immunogenicity and Protective Efficacy of a Fusion Protein Tuberculosis Vaccine Combining Five Esx Family Proteins. Front Cell Infect Microbiol 2017; 7:226. [PMID: 28620588 PMCID: PMC5449442 DOI: 10.3389/fcimb.2017.00226] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 05/16/2017] [Indexed: 11/13/2022] Open
Abstract
One strategy to develop the next generation of tuberculosis vaccines is to construct subunit vaccines based on T cell antigens. In this study, we have evaluated the vaccine potential of a fusion protein combining EsxB, EsxD, EsxG, EsxU, and EsxM of Mycobacterium tuberculosis (M. tb). This recombinant protein, named BM, was expressed in and purified from Escherichia coli. Immunization of C57BL/6 mice with purified BM protein formulated in Freund's incomplete adjuvant induced the production of Th1 cytokines (IFN-γ, TNF, and IL-2) and multifunctional CD4+ T cells. Vaccination of BALB/c mice with BM protein followed by intravenous challenge with Mycobacterium bovis BCG resulted in better levels of protection than the two leading antigens, Ag85A and PPE18. Taken together, these results indicate that BM is a protective antigen. Future studies to combine BM with other antigens and evaluate its effectiveness as a booster of BCG or as a therapeutic vaccine are warranted.
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Affiliation(s)
- Zhi-Hao Xiang
- State Key Laboratory of Genetic Engineering, School of Life Science, Institute of Genetics, Fudan UniversityShanghai, China
| | - Rui-Feng Sun
- State Key Laboratory of Genetic Engineering, School of Life Science, Institute of Genetics, Fudan UniversityShanghai, China
| | - Chen Lin
- State Key Laboratory of Genetic Engineering, School of Life Science, Institute of Genetics, Fudan UniversityShanghai, China
| | - Fu-Zeng Chen
- State Key Laboratory of Genetic Engineering, School of Life Science, Institute of Genetics, Fudan UniversityShanghai, China
| | - Jun-Tao Mai
- Department of Molecular Genetics, University of TorontoToronto, ON, Canada
| | - Yu-Xiao Liu
- State Key Laboratory of Genetic Engineering, School of Life Science, Institute of Genetics, Fudan UniversityShanghai, China
| | - Zi-Yan Xu
- State Key Laboratory of Genetic Engineering, School of Life Science, Institute of Genetics, Fudan UniversityShanghai, China
| | - Lu Zhang
- State Key Laboratory of Genetic Engineering, School of Life Science, Institute of Genetics, Fudan UniversityShanghai, China.,Key Laboratory of Medical Molecular Virology of Ministries of Education and Health, Fudan UniversityShanghai, China.,Shanghai Engineering Research Center of Industrial MicroorganismsShanghai, China
| | - Jun Liu
- State Key Laboratory of Genetic Engineering, School of Life Science, Institute of Genetics, Fudan UniversityShanghai, China.,Department of Molecular Genetics, University of TorontoToronto, ON, Canada
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Awuh JA, Flo TH. Molecular basis of mycobacterial survival in macrophages. Cell Mol Life Sci 2017; 74:1625-1648. [PMID: 27866220 PMCID: PMC11107535 DOI: 10.1007/s00018-016-2422-8] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Revised: 11/06/2016] [Accepted: 11/14/2016] [Indexed: 12/31/2022]
Abstract
Macrophages play an essential role in the immune system by ingesting and degrading invading pathogens, initiating an inflammatory response and instructing adaptive immune cells, and resolving inflammation to restore homeostasis. More interesting is the fact that some bacteria have evolved to use macrophages as a natural habitat and tools of spread in the host, e.g., Mycobacterium tuberculosis (Mtb) and some non-tuberculous mycobacteria (NTM). Mtb is considered one of humanity's most successful pathogens and is the causal agent of tuberculosis, while NTMs cause opportunistic infections all of which are of significant public health concern. Here, we describe mechanisms by which intracellular pathogens, with an emphasis on mycobacteria, manipulate macrophage functions to circumvent killing and live inside these cells even under considerable immunological pressure. Such macrophage functions include the selective evasion or engagement of pattern recognition receptors, production of cytokines, reactive oxygen and nitrogen species, phagosome maturation, as well as other killing mechanisms like autophagy and cell death. A clear understanding of host responses elicited by a specific pathogen and strategies employed by the microbe to evade or exploit these is of significant importance for the development of effective vaccines and targeted immunotherapy against persistent intracellular infections like tuberculosis.
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Affiliation(s)
- Jane Atesoh Awuh
- Centre of Molecular Inflammation Research, Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, PB 8905, 7491, Trondheim, Norway
| | - Trude Helen Flo
- Centre of Molecular Inflammation Research, Department of Cancer Research and Molecular Medicine, Norwegian University of Science and Technology, PB 8905, 7491, Trondheim, Norway.
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Gaur A, Sharma VK, Shree S, Rai N, Ramachandran R. Characterization of EccA3, a CbbX family ATPase from the ESX-3 secretion pathway of M. tuberculosis. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2017; 1865:715-724. [PMID: 28400297 DOI: 10.1016/j.bbapap.2017.04.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Revised: 04/06/2017] [Accepted: 04/07/2017] [Indexed: 01/08/2023]
Abstract
EccA family proteins are conserved components of ESX secretion pathways in M. tuberculosis H37Rv. Here, we report the characterization of EccA3 (Rv0282), a CbbX family AAA (ATPases Associated with diverse cellular Activities) protein from the ESX-3 pathway that is required for in vitro growth of mycobacteria, secretion of virulence factors, and acquisition of iron and zinc. EccA3 is a thermostable ATPase with a molecular weight of ~68kDa. It exists as a dodecamer in the apo form and associates as a hexamer in the presence of ATP. Its C-terminal region consists of a CbbX-like AAA-domain while the N-terminal region contains a tetratricopeptide repeat (TPR) domain with lower homology to other EccA-type proteins. Further, the C-terminal domain functions as the oligomerization domain and also exhibits ATPase activity. Mutational analysis, steady state kinetics and molecular docking studies identify R573 as the important 'sensor arginine' and R505 as an 'arginine finger' in EccA3. Dynamic fluorescence quenching experiments suggest that the N-terminal domain moves closer to the C-terminal domain upon ATP-binding. The ATP-dependent 'open-close' relative movements of the two domains might help EccA3 interaction and secretion of essential virulence factors.
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Affiliation(s)
- Amit Gaur
- Molecular and Structural Biology Division, CSIR-Central Drug Research Institute, Sector-10, Jankipuram Extension, Lucknow, 226031, UP, India
| | - Vijay Kumar Sharma
- Molecular and Structural Biology Division, CSIR-Central Drug Research Institute, Sector-10, Jankipuram Extension, Lucknow, 226031, UP, India
| | - Sonal Shree
- Molecular and Structural Biology Division, CSIR-Central Drug Research Institute, Sector-10, Jankipuram Extension, Lucknow, 226031, UP, India
| | - Niyati Rai
- Molecular and Structural Biology Division, CSIR-Central Drug Research Institute, Sector-10, Jankipuram Extension, Lucknow, 226031, UP, India
| | - Ravishankar Ramachandran
- Molecular and Structural Biology Division, CSIR-Central Drug Research Institute, Sector-10, Jankipuram Extension, Lucknow, 226031, UP, India.
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Abstract
Type VII secretion (T7S) systems of mycobacteria secrete substrates over the unusual diderm cell envelope. Furthermore, T7S gene clusters are present throughout the phylum Actinobacteria, and functional T7S-like systems have been identified in Firmicutes. Most of the T7S substrates can be divided into two families: the Esx proteins, which are found in both Firmicutes and Actinobacteria, and the PE and PPE proteins, which are more mycobacterium-specific. Members of both families have been shown to be secreted as folded heterodimers, suggesting that this is a conserved feature of T7S substrates. Most knowledge of the mechanism of T7S and the roles of T7S systems in virulence comes from studies of pathogenic mycobacteria. These bacteria can contain up to five T7S systems, called ESX-1 to ESX-5, each having its own role in bacterial physiology and virulence. In this article, we discuss the general composition of T7S systems and the role of the individual components in secretion. These conserved components include two membrane proteins with (predicted) enzymatic activities: a predicted ATPase (EccC), likely to be required for energy provision of T7S, and a subtilisin-like protease (MycP) involved in processing of specific substrates. Additionally, we describe the role of a conserved intracellular chaperone in T7S substrate recognition, based on recently published crystal structures and molecular analysis. Finally, we discuss system-specific features of the different T7S systems in mycobacteria and their role in pathogenesis and provide an overview of the role of T7S in virulence of other pathogenic bacteria.
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Mycobacterium tuberculosis EsxH inhibits ESCRT-dependent CD4 + T-cell activation. Nat Microbiol 2016; 2:16232. [PMID: 27918526 DOI: 10.1038/nmicrobiol.2016.232] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Accepted: 10/17/2016] [Indexed: 01/10/2023]
Abstract
Mycobacterium tuberculosis (Mtb) establishes a persistent infection, despite inducing antigen-specific T-cell responses. Although T cells arrive at the site of infection, they do not provide sterilizing immunity. The molecular basis of how Mtb impairs T-cell function is not clear. Mtb has been reported to block major histocompatibility complex class II (MHC-II) antigen presentation; however, no bacterial effector or host-cell target mediating this effect has been identified. We recently found that Mtb EsxH, which is secreted by the Esx-3 type VII secretion system, directly inhibits the endosomal sorting complex required for transport (ESCRT) machinery. Here, we showed that ESCRT is required for optimal antigen processing; correspondingly, overexpression and loss-of-function studies demonstrated that EsxH inhibited the ability of macrophages and dendritic cells to activate Mtb antigen-specific CD4+ T cells. Compared with the wild-type strain, the esxH-deficient strain induced fivefold more antigen-specific CD4+ T-cell proliferation in the mediastinal lymph nodes of mice. We also found that EsxH undermined the ability of effector CD4+ T cells to recognize infected macrophages and clear Mtb. These results provide a molecular explanation for how Mtb impairs the adaptive immune response.
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Gonzalez-Perez M, Murcia M, Parra-Lopez C, Blom J, Tauch A. Deciphering the virulence factors of the opportunistic pathogen Mycobacterium colombiense. New Microbes New Infect 2016; 14:98-105. [PMID: 27818776 PMCID: PMC5072152 DOI: 10.1016/j.nmni.2016.09.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2016] [Revised: 08/02/2016] [Accepted: 09/06/2016] [Indexed: 11/17/2022] Open
Abstract
Mycobacterium avium complex (MAC) contains clinically important nontuberculous mycobacteria worldwide and is the second largest medical complex in the Mycobacterium genus after the Mycobacterium tuberculosis complex. MAC comprises several species that are closely phylogenetically related but diverse regarding their host preference, course of disease, virulence and immune response. In this study we provided immunologic and virulence-related insights into the M. colombiense genome as a model of an opportunistic pathogen in the MAC. By using bioinformatic tools we found that M. colombiense has deletions in the genes involved in p-HBA/PDIM/PGL, PLC, SL-1 and HspX production, and loss of the ESX-1 locus. This information not only sheds light on our understanding the virulence mechanisms used by opportunistic MAC pathogens but also has great potential for the designing of species-specific diagnostic tools.
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Affiliation(s)
- M.N. Gonzalez-Perez
- Microbiology Department, School of Medicine, National University of Colombia, Bogotá, Colombia
- Center for Biotechnology (CeBiTec), Bielefeld University, Bielefeld, Germany
- Corresponding author: M. N. Gonzalez-Perez, Microbiology Department, School of Medicine, National University of Colombia, Bogotá, ColombiaMicrobiology DepartmentSchool of MedicineNational University of ColombiaBogotáColombia
| | - M.I. Murcia
- Microbiology Department, School of Medicine, National University of Colombia, Bogotá, Colombia
| | - C. Parra-Lopez
- Microbiology Department, School of Medicine, National University of Colombia, Bogotá, Colombia
| | - J. Blom
- Bioinformatics and Systems Biology, Justus Liebig University Giessen, Giessen, Germany
| | - A. Tauch
- Microbiology Department, School of Medicine, National University of Colombia, Bogotá, Colombia
- Center for Biotechnology (CeBiTec), Bielefeld University, Bielefeld, Germany
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Role of Metal-Dependent Regulation of ESX-3 Secretion in Intracellular Survival of Mycobacterium tuberculosis. Infect Immun 2016; 84:2255-2263. [PMID: 27245412 DOI: 10.1128/iai.00197-16] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Accepted: 05/19/2016] [Indexed: 12/31/2022] Open
Abstract
More people die every year from Mycobacterium tuberculosis infection than from infection by any other bacterial pathogen. Type VII secretion systems (T7SS) are used by both environmental and pathogenic mycobacteria to secrete proteins across their complex cell envelope. In the nonpathogen Mycobacterium smegmatis, the ESX-1 T7SS plays a role in conjugation, and the ESX-3 T7SS is involved in metal homeostasis. In M. tuberculosis, these secretion systems have taken on roles in virulence, and they also are targets of the host immune response. ESX-3 secretes a heterodimer composed of EsxG (TB9.8) and EsxH (TB10.4), which impairs phagosome maturation in macrophages and is essential for virulence in mice. Given the importance of EsxG and EsxH during infection, we examined their regulation. With M. tuberculosis, the secretion of EsxG and EsxH was regulated in response to iron and zinc, in accordance with the previously described transcriptional response of the esx-3 locus to these metals. While iron regulated the esx-3 expression in both M. tuberculosis and M. smegmatis, there is a significant difference in the dynamics of this regulation. In M. smegmatis, the esx-3 locus behaved like other iron-regulated genes such as mbtB In M. tuberculosis, both iron and zinc modestly repressed esx-3 expression. Diminished secretion of EsxG and EsxH in response to these metals altered the interaction of M. tuberculosis with macrophages, leading to impaired intracellular M. tuberculosis survival. Our findings detail the regulatory differences of esx-3 in M. tuberculosis and M. smegmatis and demonstrate the importance of metal-dependent regulation of ESX-3 for virulence in M. tuberculosis.
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Wagner JM, Chan S, Evans TJ, Kahng S, Kim J, Arbing MA, Eisenberg D, Korotkov KV. Structures of EccB1 and EccD1 from the core complex of the mycobacterial ESX-1 type VII secretion system. BMC STRUCTURAL BIOLOGY 2016; 16:5. [PMID: 26922638 PMCID: PMC4769845 DOI: 10.1186/s12900-016-0056-6] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Accepted: 02/23/2016] [Indexed: 11/24/2022]
Abstract
Background The ESX-1 type VII secretion system is an important determinant of virulence in pathogenic mycobacteria, including Mycobacterium tuberculosis. This complicated molecular machine secretes folded proteins through the mycobacterial cell envelope to subvert the host immune response. Despite its important role in disease very little is known about the molecular architecture of the ESX-1 secretion system. Results This study characterizes the structures of the soluble domains of two conserved core ESX-1 components – EccB1 and EccD1. The periplasmic domain of EccB1 consists of 4 repeat domains and a central domain, which together form a quasi 2-fold symmetrical structure. The repeat domains of EccB1 are structurally similar to a known peptidoglycan binding protein suggesting a role in anchoring the ESX-1 system within the periplasmic space. The cytoplasmic domain of EccD1has a ubiquitin-like fold and forms a dimer with a negatively charged groove. Conclusions These structures represent a major step towards resolving the molecular architecture of the entire ESX-1 assembly and may contribute to ESX-1 targeted tuberculosis intervention strategies. Electronic supplementary material The online version of this article (doi:10.1186/s12900-016-0056-6) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jonathan M Wagner
- Department of Molecular & Cellular Biochemistry and Center for Structural Biology, University of Kentucky, 741 South Limestone, Lexington, KY, 40536, USA. .,Present address: Department of Molecular Physiology and Biological Physics and The Myles H. Thaler Center for AIDS and Human Retrovirus Research, University of Virginia, Charlottesville, VA, USA.
| | - Sum Chan
- UCLA-DOE Institute, University of California Los Angeles, Los Angeles, CA, 90095-1570, USA.
| | - Timothy J Evans
- Department of Molecular & Cellular Biochemistry and Center for Structural Biology, University of Kentucky, 741 South Limestone, Lexington, KY, 40536, USA. .,Present address: Division of Regulatory Services, College of Agriculture, Food and Environment, University of Kentucky, Lexington, KY, USA.
| | - Sara Kahng
- UCLA-DOE Institute, University of California Los Angeles, Los Angeles, CA, 90095-1570, USA.
| | - Jennifer Kim
- UCLA-DOE Institute, University of California Los Angeles, Los Angeles, CA, 90095-1570, USA.
| | - Mark A Arbing
- UCLA-DOE Institute, University of California Los Angeles, Los Angeles, CA, 90095-1570, USA.
| | - David Eisenberg
- UCLA-DOE Institute, Departments of Biological Chemistry and Chemistry & Biochemistry, and Howard Hughes Medical Institute, University of California Los Angeles, Los Angeles, CA, 90095-1570, USA.
| | - Konstantin V Korotkov
- Department of Molecular & Cellular Biochemistry and Center for Structural Biology, University of Kentucky, 741 South Limestone, Lexington, KY, 40536, USA.
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Expression and production of soluble Mycobacterium tuberculosis H37Rv mycosin-3. Biochem Biophys Rep 2016; 5:448-452. [PMID: 28955852 PMCID: PMC5600315 DOI: 10.1016/j.bbrep.2016.02.005] [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: 12/15/2015] [Revised: 02/03/2016] [Accepted: 02/04/2016] [Indexed: 11/29/2022] Open
Abstract
Mycobacteria encode five type VII secretion system (T7SS) or ESX for nutrient acquisition and virulence. Mycosins are membrane-anchored components of ESX with serine protease activity but an unidentified substrate range. Establishing the substrate specificity of individual mycosins will help to elucidate individual ESX functions. Mycosin-1 and -3 orthologues from two environmental mycobacterial species, Mycobacterium smegmatis and Mycobacterium thermoresistibile, have been heterologously produced, but mycosins from Mycobacterium tuberculosis (Mtb) remain to be studied. Here we describe the successful production of Mtb mycosin-3 as a first step in investigating its structure and function. Production of soluble mycosin-3 from Mtb H37Rv. Soluble mycosin-3 was produced in E. coli strain Arctic Express. Soluble mycosin-3 without its N-terminal extension region was produced.
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Tufariello JM, Chapman JR, Kerantzas CA, Wong KW, Vilchèze C, Jones CM, Cole LE, Tinaztepe E, Thompson V, Fenyö D, Niederweis M, Ueberheide B, Philips JA, Jacobs WR. Separable roles for Mycobacterium tuberculosis ESX-3 effectors in iron acquisition and virulence. Proc Natl Acad Sci U S A 2016; 113:E348-57. [PMID: 26729876 PMCID: PMC4725510 DOI: 10.1073/pnas.1523321113] [Citation(s) in RCA: 132] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Mycobacterium tuberculosis (Mtb) encodes five type VII secretion systems (T7SS), designated ESX-1-ESX-5, that are critical for growth and pathogenesis. The best characterized is ESX-1, which profoundly impacts host cell interactions. In contrast, the ESX-3 T7SS is implicated in metal homeostasis, but efforts to define its function have been limited by an inability to recover deletion mutants. We overcame this impediment using medium supplemented with various iron complexes to recover mutants with deletions encompassing select genes within esx-3 or the entire operon. The esx-3 mutants were defective in uptake of siderophore-bound iron and dramatically accumulated cell-associated mycobactin siderophores. Proteomic analyses of culture filtrate revealed that secretion of EsxG and EsxH was codependent and that EsxG-EsxH also facilitated secretion of several members of the proline-glutamic acid (PE) and proline-proline-glutamic acid (PPE) protein families (named for conserved PE and PPE N-terminal motifs). Substrates that depended on EsxG-EsxH for secretion included PE5, encoded within the esx-3 locus, and the evolutionarily related PE15-PPE20 encoded outside the esx-3 locus. In vivo characterization of the mutants unexpectedly showed that the ESX-3 secretion system plays both iron-dependent and -independent roles in Mtb pathogenesis. PE5-PPE4 was found to be critical for the siderophore-mediated iron-acquisition functions of ESX-3. The importance of this iron-acquisition function was dependent upon host genotype, suggesting a role for ESX-3 secretion in counteracting host defense mechanisms that restrict iron availability. Further, we demonstrate that the ESX-3 T7SS secretes certain effectors that are important for iron uptake while additional secreted effectors modulate virulence in an iron-independent fashion.
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Affiliation(s)
- JoAnn M Tufariello
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY 10461; Department of Medicine, Albert Einstein College of Medicine, Bronx, NY 10461
| | - Jessica R Chapman
- Office of Collaborative Science, New York University School of Medicine, New York, NY 10016
| | - Christopher A Kerantzas
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY 10461
| | - Ka-Wing Wong
- Shanghai Public Health Clinical Center, Key Laboratory of Medical Molecular Virology of the Ministry of Education/Health, School of Basic Medical Sciences, Fudan University, Shanghai 201508, China
| | - Catherine Vilchèze
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY 10461; Howard Hughes Medical Institute, Albert Einstein College of Medicine, Bronx, NY 10461
| | - Christopher M Jones
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Laura E Cole
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY 10461
| | - Emir Tinaztepe
- Division of Infectious Diseases, Department of Medicine, New York University School of Medicine, New York, NY 10016
| | - Victor Thompson
- Division of Infectious Diseases, Department of Medicine, New York University School of Medicine, New York, NY 10016
| | - David Fenyö
- Laboratory of Computational Proteomics, Center for Health Informatics and Bioinformatics, New York University School of Medicine, New York, NY 10016; Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016
| | - Michael Niederweis
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL 35294
| | - Beatrix Ueberheide
- Office of Collaborative Science, New York University School of Medicine, New York, NY 10016; Department of Biochemistry and Molecular Pharmacology, New York University School of Medicine, New York, NY 10016
| | - Jennifer A Philips
- Division of Infectious Diseases, Department of Medicine, New York University School of Medicine, New York, NY 10016;
| | - William R Jacobs
- Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY 10461; Howard Hughes Medical Institute, Albert Einstein College of Medicine, Bronx, NY 10461;
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