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Luo G, Ming T, Yang L, He L, Tao T, Wang Y. Modulators targeting protein-protein interactions in Mycobacterium tuberculosis. Microbiol Res 2024; 284:127675. [PMID: 38636239 DOI: 10.1016/j.micres.2024.127675] [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: 09/27/2023] [Revised: 03/03/2024] [Accepted: 03/04/2024] [Indexed: 04/20/2024]
Abstract
Tuberculosis (TB) is a chronic infectious disease caused by Mycobacterium tuberculosis (M. tuberculosis), mainly transmitted through droplets to infect the lungs, and seriously affecting patients' health and quality of life. Clinically, anti-TB drugs often entail side effects and lack efficacy against resistant strains. Thus, the exploration and development of novel targeted anti-TB medications are imperative. Currently, protein-protein interactions (PPIs) offer novel avenues for anti-TB drug development, and the study of targeted modulators of PPIs in M. tuberculosis has become a prominent research focus. Furthermore, a comprehensive PPI network has been constructed using computational methods and bioinformatics tools. This network allows for a more in-depth analysis of the structural biology of PPIs and furnishes essential insights for the development of targeted small-molecule modulators. Furthermore, this article provides a detailed overview of the research progress and regulatory mechanisms of PPI modulators in M. tuberculosis, the causative agent of TB. Additionally, it summarizes potential targets for anti-TB drugs and discusses the prospects of existing PPI modulators.
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Affiliation(s)
- Guofeng Luo
- School of Medical and Life Sciences, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
| | - Tianqi Ming
- State Key Laboratory of Southwestern Chinese Medicine Resources, Department of Pharmacology, Chengdu University of Traditional Chinese Medicine, Chengdu 611137, China
| | - Luchuan Yang
- Institute of traditional Chinese medicine, Sichuan College of traditional Chinese Medicine (Sichuan Second Hospital of TCM), Chengdu 610031, China
| | - Lei He
- Institute of traditional Chinese medicine, Sichuan College of traditional Chinese Medicine (Sichuan Second Hospital of TCM), Chengdu 610031, China
| | - Tao Tao
- Institute of traditional Chinese medicine, Sichuan College of traditional Chinese Medicine (Sichuan Second Hospital of TCM), Chengdu 610031, China
| | - Yanmei Wang
- Institute of traditional Chinese medicine, Sichuan College of traditional Chinese Medicine (Sichuan Second Hospital of TCM), Chengdu 610031, China.
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2
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Khan H, Paul P, Goar H, Bamniya B, Baid N, Sarkar D. Mycobacterium tuberculosis PhoP integrates stress response to intracellular survival by regulating cAMP level. eLife 2024; 13:RP92136. [PMID: 38739431 PMCID: PMC11090507 DOI: 10.7554/elife.92136] [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] [Indexed: 05/14/2024] Open
Abstract
Survival of Mycobacterium tuberculosis within the host macrophages requires the bacterial virulence regulator PhoP, but the underlying reason remains unknown. 3',5'-Cyclic adenosine monophosphate (cAMP) is one of the most widely used second messengers, which impacts a wide range of cellular responses in microbial pathogens including M. tuberculosis. Herein, we hypothesized that intra-bacterial cAMP level could be controlled by PhoP since this major regulator plays a key role in bacterial responses against numerous stress conditions. A transcriptomic analysis reveals that PhoP functions as a repressor of cAMP-specific phosphodiesterase (PDE) Rv0805, which hydrolyzes cAMP. In keeping with these results, we find specific recruitment of the regulator within the promoter region of rv0805 PDE, and absence of phoP or ectopic expression of rv0805 independently accounts for elevated PDE synthesis, leading to the depletion of intra-bacterial cAMP level. Thus, genetic manipulation to inactivate PhoP-rv0805-cAMP pathway decreases cAMP level, stress tolerance, and intracellular survival of the bacillus.
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Affiliation(s)
- Hina Khan
- CSIR, Institute of Microbial TechnologyChandigarhIndia
| | - Partha Paul
- CSIR, Institute of Microbial TechnologyChandigarhIndia
| | - Harsh Goar
- CSIR, Institute of Microbial TechnologyChandigarhIndia
| | - Bhanwar Bamniya
- CSIR, Institute of Microbial TechnologyChandigarhIndia
- Academy of Scientific and Innovative ResearchGhaziabadIndia
| | - Navin Baid
- CSIR, Institute of Microbial TechnologyChandigarhIndia
| | - Dibyendu Sarkar
- CSIR, Institute of Microbial TechnologyChandigarhIndia
- Academy of Scientific and Innovative ResearchGhaziabadIndia
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3
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Veerapandian R, Gadad SS, Jagannath C, Dhandayuthapani S. Live Attenuated Vaccines against Tuberculosis: Targeting the Disruption of Genes Encoding the Secretory Proteins of Mycobacteria. Vaccines (Basel) 2024; 12:530. [PMID: 38793781 PMCID: PMC11126151 DOI: 10.3390/vaccines12050530] [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: 04/08/2024] [Revised: 05/07/2024] [Accepted: 05/08/2024] [Indexed: 05/26/2024] Open
Abstract
Tuberculosis (TB), a chronic infectious disease affecting humans, causes over 1.3 million deaths per year throughout the world. The current preventive vaccine BCG provides protection against childhood TB, but it fails to protect against pulmonary TB. Multiple candidates have been evaluated to either replace or boost the efficacy of the BCG vaccine, including subunit protein, DNA, virus vector-based vaccines, etc., most of which provide only short-term immunity. Several live attenuated vaccines derived from Mycobacterium tuberculosis (Mtb) and BCG have also been developed to induce long-term immunity. Since Mtb mediates its virulence through multiple secreted proteins, these proteins have been targeted to produce attenuated but immunogenic vaccines. In this review, we discuss the characteristics and prospects of live attenuated vaccines generated by targeting the disruption of the genes encoding secretory mycobacterial proteins.
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Affiliation(s)
- Raja Veerapandian
- Center of Emphasis in Infectious Diseases, Department of Molecular and Translational Medicine, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center El Paso, El Paso, TX 79905, USA
| | - Shrikanth S. Gadad
- Center of Emphasis in Cancer, Department of Molecular and Translational Medicine, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center El Paso, El Paso, TX 79905, USA
| | - Chinnaswamy Jagannath
- Department of Pathology and Genomic Medicine, Houston Methodist Research Institute & Weill Cornell Medical College, Houston, TX 77030, USA
| | - Subramanian Dhandayuthapani
- Center of Emphasis in Infectious Diseases, Department of Molecular and Translational Medicine, Paul L. Foster School of Medicine, Texas Tech University Health Sciences Center El Paso, El Paso, TX 79905, USA
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Nicholson KR, Cronin RM, Prest RJ, Menon AR, Yang Y, Jennisch MK, Champion MM, Tobin DM, Champion PA. The antagonistic transcription factors, EspM and EspN, regulate the ESX-1 secretion system in M. marinum. mBio 2024; 15:e0335723. [PMID: 38445877 PMCID: PMC11005418 DOI: 10.1128/mbio.03357-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2023] [Accepted: 02/13/2024] [Indexed: 03/07/2024] Open
Abstract
Bacterial pathogens use protein secretion systems to transport virulence factors and regulate gene expression. Among pathogenic mycobacteria, including Mycobacterium tuberculosis and Mycobacterium marinum, the ESAT-6 system 1 (ESX-1) secretion is crucial for host interaction. Secretion of protein substrates by the ESX-1 secretion system disrupts phagosomes, allowing mycobacteria cytoplasmic access during macrophage infections. Deletion or mutation of the ESX-1 system attenuates mycobacterial pathogens. Pathogenic mycobacteria respond to the presence or absence of the ESX-1 system in the cytoplasmic membrane by altering transcription. Under laboratory conditions, the EspM repressor and WhiB6 activator control transcription of specific ESX-1-responsive genes, including the ESX-1 substrate genes. However, deleting the espM or whiB6 gene does not phenocopy the deletion of the ESX-1 substrate genes during macrophage infection by M. marinum. In this study, we identified EspN, a critical transcription factor whose activity is masked by the EspM repressor under laboratory conditions. In the absence of EspM, EspN activates transcription of whiB6 and ESX-1 genes during both laboratory growth and macrophage infection. EspN is also independently required for M. marinum growth within and cytolysis of macrophages, similar to the ESX-1 genes, and for disease burden in a zebrafish larval model of infection. These findings suggest that EspN and EspM coordinate to counterbalance the regulation of the ESX-1 system and support mycobacterial pathogenesis.IMPORTANCEPathogenic mycobacteria, which are responsible for tuberculosis and other long-term diseases, use the ESX-1 system to transport proteins that control the host response to infection and promote bacterial survival. In this study, we identify an undescribed transcription factor that controls the expression of ESX-1 genes and is required for both macrophage and animal infection. However, this transcription factor is not the primary regulator of ESX-1 genes under standard laboratory conditions. These findings identify a critical transcription factor that likely controls expression of a major virulence pathway during infection, but whose effect is not detectable with standard laboratory strains and growth conditions.
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Affiliation(s)
- Kathleen R. Nicholson
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Notre Dame, Indiana, USA
| | - Rachel M. Cronin
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Notre Dame, Indiana, USA
| | - Rebecca J. Prest
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Notre Dame, Indiana, USA
| | - Aruna R. Menon
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, North Carolina, USA
| | - Yuwei Yang
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Notre Dame, Indiana, USA
| | - Madeleine K. Jennisch
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Notre Dame, Indiana, USA
| | - Matthew M. Champion
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Notre Dame, Indiana, USA
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana, USA
| | - David M. Tobin
- Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, North Carolina, USA
- Department of Immunology, Duke University School of Medicine, Durham, North Carolina, USA
| | - Patricia A. Champion
- Department of Biological Sciences, Eck Institute for Global Health, University of Notre Dame, Notre Dame, Indiana, USA
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5
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Stupar M, Tan L, Kerr ED, De Voss CJ, Forde BM, Schulz BL, West NP. TcrXY is an acid-sensing two-component transcriptional regulator of Mycobacterium tuberculosis required for persistent infection. Nat Commun 2024; 15:1615. [PMID: 38388565 PMCID: PMC10883919 DOI: 10.1038/s41467-024-45343-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Accepted: 01/22/2024] [Indexed: 02/24/2024] Open
Abstract
The ability of Mycobacterium tuberculosis (Mtb) to persist in the host complicates and prolongs tuberculosis (TB) patient chemotherapy. Here we demonstrate that a neglected two-component system (TCS) of Mtb, TcrXY, is an autoregulated acid-sensing TCS that controls a functionally diverse 70-gene regulon required for bacterial persistence. Characterisation of two representatives of this regulon, Rv3706c and Rv3705A, implicate these genes as key determinants for the survival of Mtb in vivo by serving as important effectors to mitigate redox stress at acidic pH. We show that genetic silencing of the response regulator tcrX using CRISPR interference attenuates the persistence of Mtb during chronic mouse infection and improves treatment with the two front-line anti-TB drugs, rifampicin and isoniazid. We propose that targeting TcrXY signal transduction blocks the ability of Mtb to sense and respond to acid stress, resulting in a disordered program of persistence to render the organism vulnerable to existing TB chemotherapy.
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Affiliation(s)
- Miljan Stupar
- School of Chemistry and Molecular Biosciences, Australian Infectious Disease Research Centre, The University of Queensland, Brisbane, Australia
| | - Lendl Tan
- School of Chemistry and Molecular Biosciences, Australian Infectious Disease Research Centre, The University of Queensland, Brisbane, Australia
| | - Edward D Kerr
- School of Chemistry and Molecular Biosciences, Australian Infectious Disease Research Centre, The University of Queensland, Brisbane, Australia
| | - Christopher J De Voss
- School of Chemistry and Molecular Biosciences, Australian Infectious Disease Research Centre, The University of Queensland, Brisbane, Australia
| | - Brian M Forde
- Faculty of Medicine, UQ Centre for Clinical Research, The University of Queensland, Brisbane, Australia
| | - Benjamin L Schulz
- School of Chemistry and Molecular Biosciences, Australian Infectious Disease Research Centre, The University of Queensland, Brisbane, Australia
| | - Nicholas P West
- School of Chemistry and Molecular Biosciences, Australian Infectious Disease Research Centre, The University of Queensland, Brisbane, Australia.
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6
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Belardinelli JM, Arora D, Avanzi C, Wheat WH, Bryant JM, Spencer JS, Blundell TL, Parkhill J, Floto RA, Jackson M. Clinically relevant mutations in the PhoR sensor kinase of host-adapted Mycobacterium abscessus isolates impact response to acidic pH and virulence. Microbiol Spectr 2023; 11:e0158823. [PMID: 37874174 PMCID: PMC10715180 DOI: 10.1128/spectrum.01588-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Accepted: 09/14/2023] [Indexed: 10/25/2023] Open
Abstract
IMPORTANCE Difficult-to-treat pulmonary infections caused by nontuberculous mycobacteria of the Mycobacterium abscessus group have been steadily increasing in the USA and globally. Owing to the relatively recent recognition of M. abscessus as a human pathogen, basic and translational research to address critical gaps in diagnosis, treatment, and prevention of diseases caused by this microorganism has been lagging behind that of the better-known mycobacterial pathogen, Mycobacterium tuberculosis. To begin unraveling the molecular mechanisms of pathogenicity of M. abscessus, we here focus on the study of a two-component regulator known as PhoPR which we found to be under strong evolutionary pressure during human lung infection. We show that PhoPR is activated at acidic pH and serves to regulate a defined set of genes involved in host adaptation. Accordingly, clinical isolates from chronically infected human lungs tend to hyperactivate this regulator enabling M. abscessus to escape macrophage killing.
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Affiliation(s)
- Juan M Belardinelli
- Department of Microbiology, Immunology and Pathology, Mycobacteria Research Laboratories, Colorado State University , Fort Collins, Colorado, USA
| | - Divya Arora
- Department of Medicine, Molecular Immunity Unit, University of Cambridge, MRC-Laboratory of Molecular Biology , Cambridge, United Kingdom
| | - Charlotte Avanzi
- Department of Microbiology, Immunology and Pathology, Mycobacteria Research Laboratories, Colorado State University , Fort Collins, Colorado, USA
| | - William H Wheat
- Department of Microbiology, Immunology and Pathology, Mycobacteria Research Laboratories, Colorado State University , Fort Collins, Colorado, USA
| | - Josephine M Bryant
- Department of Medicine, Molecular Immunity Unit, University of Cambridge, MRC-Laboratory of Molecular Biology , Cambridge, United Kingdom
- University of Cambridge Centre for AI in Medicine , Cambridge, United Kingdom
| | - John S Spencer
- Department of Microbiology, Immunology and Pathology, Mycobacteria Research Laboratories, Colorado State University , Fort Collins, Colorado, USA
| | - Tom L Blundell
- Department of Biochemistry, University of Cambridge , Cambridge, United Kingdom
| | - Julian Parkhill
- Wellcome Sanger Institute , Hinxton, United Kingdom
- Department of Veterinary Medicine, University of Cambridge , Cambridge, United Kingdom
| | - R Andres Floto
- Department of Medicine, Molecular Immunity Unit, University of Cambridge, MRC-Laboratory of Molecular Biology , Cambridge, United Kingdom
- University of Cambridge Centre for AI in Medicine , Cambridge, United Kingdom
- Cambridge Centre for Lung Infection, Papworth Hospital , Cambridge, United Kingdom
| | - Mary Jackson
- Department of Microbiology, Immunology and Pathology, Mycobacteria Research Laboratories, Colorado State University , Fort Collins, Colorado, USA
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7
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Singh PR, Goar H, Paul P, Mehta K, Bamniya B, Vijjamarri AK, Bansal R, Khan H, Karthikeyan S, Sarkar D. Dual functioning by the PhoR sensor is a key determinant to Mycobacterium tuberculosis virulence. PLoS Genet 2023; 19:e1011070. [PMID: 38100394 PMCID: PMC10723718 DOI: 10.1371/journal.pgen.1011070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2023] [Accepted: 11/16/2023] [Indexed: 12/17/2023] Open
Abstract
PhoP-PhoR, one of the 12 two-component systems (TCSs) that empower M. tuberculosis to sense and adapt to diverse environmental conditions, remains essential for virulence, and therefore, represents a major target to develop novel anti-TB therapies. Although both PhoP and PhoR have been structurally characterized, the signal(s) that this TCS responds to remains unknown. Here, we show that PhoR is a sensor of acidic pH/high salt conditions, which subsequently activate PhoP via phosphorylation. In keeping with this, transcriptomic data uncover that acidic pH- inducible expression of PhoP regulon is significantly inhibited in a PhoR-deleted M. tuberculosis. Strikingly, a set of PhoP regulon genes displayed a low pH-dependent activation even in the absence of PhoR, suggesting the presence of non-canonical mechanism(s) of PhoP activation. Using genome-wide interaction-based screening coupled with phosphorylation assays, we identify a non-canonical mechanism of PhoP phosphorylation by the sensor kinase PrrB. To investigate how level of P~PhoP is regulated, we discovered that in addition to its kinase activity PhoR functions as a phosphatase of P~PhoP. Our subsequent results identify the motif/residues responsible for kinase/phosphatase dual functioning of PhoR. Collectively, these results uncover that contrasting kinase and phosphatase functions of PhoR determine the homeostatic mechanism of regulation of intra-mycobacterial P~PhoP which controls the final output of the PhoP regulon. Together, these results connect PhoR to pH-dependent activation of PhoP with downstream functioning of the regulator. Thus, PhoR plays a central role in mycobacterial adaptation to low pH conditions within the host macrophage phagosome, and a PhoR-deleted M. tuberculosis remains significantly attenuated in macrophages and animal models.
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Affiliation(s)
| | - Harsh Goar
- CSIR-Institute of Microbial Technology, Sector 39 A, Chandigarh, India
| | - Partha Paul
- CSIR-Institute of Microbial Technology, Sector 39 A, Chandigarh, India
| | - Khushboo Mehta
- CSIR-Institute of Microbial Technology, Sector 39 A, Chandigarh, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
| | - Bhanwar Bamniya
- CSIR-Institute of Microbial Technology, Sector 39 A, Chandigarh, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
| | | | - Roohi Bansal
- CSIR-Institute of Microbial Technology, Sector 39 A, Chandigarh, India
| | - Hina Khan
- CSIR-Institute of Microbial Technology, Sector 39 A, Chandigarh, India
| | - Subramanian Karthikeyan
- CSIR-Institute of Microbial Technology, Sector 39 A, Chandigarh, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
| | - Dibyendu Sarkar
- CSIR-Institute of Microbial Technology, Sector 39 A, Chandigarh, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, India
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8
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Yandrapally S, Agarwal A, Chatterjee A, Sarkar S, Mohareer K, Banerjee S. Mycobacterium tuberculosis EspR modulates Th1-Th2 shift by transcriptionally regulating IL-4, steering increased mycobacterial persistence and HIV propagation during co-infection. Front Immunol 2023; 14:1276817. [PMID: 37928551 PMCID: PMC10621737 DOI: 10.3389/fimmu.2023.1276817] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2023] [Accepted: 10/06/2023] [Indexed: 11/07/2023] Open
Abstract
Mycobacterium tuberculosis (Mtb) and HIV are known to mutually support each other during co-infection by multiple mechanisms. This synergistic influence could be either by direct interactions or indirectly through secreted host or pathogen factors that work in trans. Mtb secretes several virulence factors to modulate the host cellular environment for its persistence and escaping cell-intrinsic immune responses. We hypothesized that secreted Mtb transcription factors that target the host nucleus can directly interact with host DNA element(s) or HIV LTR during co-infection, thereby modulating immune gene expression, or driving HIV transcription, helping the synergistic existence of Mtb and HIV. Here, we show that the Mtb-secreted protein, EspR, a transcription regulator, increased mycobacterial persistence and HIV propagation during co-infection. Mechanistically, EspR localizes to the nucleus of the host cells during infection, binds to its putative cognate motif on the promoter region of the host IL-4 gene, activating IL-4 gene expression, causing high IL-4 titers that induce a Th2-type microenvironment, shifting the macrophage polarization to an M2 state as evident from CD206 dominant population over CD64. This compromised the clearance of the intracellular mycobacteria and enhanced HIV propagation. It was interesting to note that EspR did not bind to HIV LTR, although its transient expression increased viral propagation. This is the first report of an Mtb transcription factor directly regulating a host cytokine gene. This augments our understanding of the evolution of Mtb immune evasion strategies and unveils how Mtb aggravates comorbidities, such as HIV co-infection, by modulating the immune microenvironment.
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9
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The EspN transcription factor is an infection-dependent regulator of the ESX-1 system in M. marinum. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.15.528779. [PMID: 36824794 PMCID: PMC9948972 DOI: 10.1101/2023.02.15.528779] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/18/2023]
Abstract
Bacterial pathogens use protein secretion systems to translocate virulence factors into the host and to control bacterial gene expression. The ESX-1 (ESAT-6 system 1) secretion system facilitates disruption of the macrophage phagosome during infection, enabling access to the cytoplasm, and regulates widespread gene expression in the mycobacterial cell. The transcription factors contributing to the ESX-1 transcriptional network during mycobacterial infection are not known. We showed that the EspM and WhiB6 transcription factors regulate the ESX-1 transcriptional network in vitro but are dispensable for macrophage infection by Mycobacterium marinum . In this study, we used our understanding of the ESX-1 system to identify EspN, a critical transcription factor that controls expression of the ESX-1 genes during infection, but whose effect is not detectable under standard laboratory growth conditions. Under laboratory conditions, EspN activity is masked by the EspM repressor. In the absence of EspM, we found that EspN is required for ESX-1 function because it activates expression of the whiB6 transcription factor gene, and specific ESX-1 substrate and secretory component genes. Unlike the other transcription factors that regulate ESX-1, EspN is required for M. marinum growth within and cytolysis of macrophages, and for disease burden in a zebrafish larval model of infection. These findings demonstrate that EspN is an infection-dependent regulator of the ESX-1 transcriptional network, which is essential for mycobacterial pathogenesis. Moreover, our findings suggest that ESX-1 expression is controlled by a genetic switch that responds to host specific signals. Importance Pathogenic mycobacteria cause acute and long-term diseases, including human tuberculosis. The ESX-1 system transports proteins that control the host response to infection and promotes bacterial survival. Although ESX-1 transports proteins, it also controls gene expression in the bacteria. In this study, we identify an undescribed transcription factor that controls the expression of ESX-1 genes, and is required for both macrophage and animal infection. However, this transcription factor is not the primary regulator of ESX-1 genes under standard laboratory conditions. These findings identify a critical transcription factor that controls expression of a major virulence pathway during infection, but whose effect is not detectable with standard laboratory strains and growth conditions.
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10
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Khan H, Paul P, Sevalkar RR, Kachhap S, Singh B, Sarkar D. Convergence of two global regulators to coordinate expression of essential virulence determinants of Mycobacterium tuberculosis. eLife 2022; 11:80965. [PMID: 36350294 PMCID: PMC9645806 DOI: 10.7554/elife.80965] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Accepted: 10/24/2022] [Indexed: 11/11/2022] Open
Abstract
Cyclic AMP (cAMP) is known to function as a global regulator of Mycobacterium tuberculosis gene expression. Sequence-based transcriptomic profiling identified the mycobacterial regulon controlled by the cAMP receptor protein, CRP. In this study, we identified a new subset of CRP-associated genes including virulence determinants which are also under the control of a major regulator, PhoP. Our results suggest that PhoP as a DNA binding transcription factor, impacts expression of these genes, and phosphorylated PhoP promotes CRP recruitment at the target promoters. Further, we uncover a distinct regulatory mechanism showing that activation of these genes requires direct recruitment of both PhoP and CRP at their target promoters. The most fundamental biological insight is derived from the inhibition of CRP binding at the regulatory regions in a PhoP-deleted strain owing to CRP-PhoP protein-protein interactions. Based on these results, a model is proposed suggesting how CRP and PhoP function as co-activators of the essential pathogenic determinants. Taken together, these results uncover a novel mode of regulation where a complex of two interacting virulence factors impact expression of virulence determinants. These results have significant implications on TB pathogenesis.
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Affiliation(s)
- Hina Khan
- CSIR-Institute of Microbial Technology
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11
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Genestet C, Refrégier G, Hodille E, Zein-Eddine R, Le Meur A, Hak F, Barbry A, Westeel E, Berland JL, Engelmann A, Verdier I, Lina G, Ader F, Dray S, Jacob L, Massol F, Venner S, Dumitrescu O. Mycobacterium tuberculosis genetic features associated with pulmonary tuberculosis severity. Int J Infect Dis 2022; 125:74-83. [PMID: 36273524 DOI: 10.1016/j.ijid.2022.10.026] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Revised: 10/13/2022] [Accepted: 10/15/2022] [Indexed: 11/06/2022] Open
Abstract
OBJECTIVES Mycobacterium tuberculosis (Mtb) infections result in a wide spectrum of clinical presentations but without proven Mtb genetic determinants. Herein, we hypothesized that the genetic features of Mtb clinical isolates, such as specific polymorphisms or microdiversity, may be linked to tuberculosis (TB) severity. METHODS A total of 234 patients with pulmonary TB (including 193 drug-susceptible and 14 monoresistant cases diagnosed between 2017 and 2020 and 27 multidrug-resistant cases diagnosed between 2010 and 2020) were stratified according to TB disease severity, and Mtb genetic features were explored using whole genome sequencing, including heterologous single-nucleotide polymorphism (SNP), calling to explore microdiversity. Finally, we performed a structural equation modeling analysis to relate TB severity to Mtb genetic features. RESULTS The clinical isolates from patients with mild TB carried mutations in genes associated with host-pathogen interaction, whereas those from patients with moderate/severe TB carried mutations associated with regulatory mechanisms. Genome-wide association study identified an SNP in the promoter of the gene coding for the virulence regulator espR, statistically associated with moderate/severe disease. Structural equation modeling and model comparisons indicated that TB severity was associated with the detection of Mtb microdiversity within clinical isolates and to the espR SNP. CONCLUSION Taken together, these results provide a new insight to better understand TB pathophysiology and could provide a new prognosis tool for pulmonary TB severity.
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Affiliation(s)
- Charlotte Genestet
- CIRI - Centre International de Recherche en Infectiologie, Ecole Normale Supérieure de Lyon, Université Claude Bernard Lyon-1, Rhône-Alpes, Lyon, France; Hospices Civils de Lyon, Institut des Agents Infectieux, Laboratoire de bactériologie, Rhône-Alpes, Lyon, France.
| | - Guislaine Refrégier
- Université Paris-Saclay, CNRS, AgroParisTech, Ecologie Systématique et Evolution, Île-de-France, Orsay, France.; Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris Sud, Université Paris-Saclay, Île-de-France, Gif-sur-Yvette, France
| | - Elisabeth Hodille
- CIRI - Centre International de Recherche en Infectiologie, Ecole Normale Supérieure de Lyon, Université Claude Bernard Lyon-1, Rhône-Alpes, Lyon, France; Hospices Civils de Lyon, Institut des Agents Infectieux, Laboratoire de bactériologie, Rhône-Alpes, Lyon, France
| | - Rima Zein-Eddine
- Université Paris-Saclay, CNRS, AgroParisTech, Ecologie Systématique et Evolution, Île-de-France, Orsay, France.; Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris Sud, Université Paris-Saclay, Île-de-France, Gif-sur-Yvette, France; Laboratory of Optics and Biosciences, CNRS-INSERM-Ecole Polytechnique, Île-de-France, Palaiseau, France
| | - Adrien Le Meur
- Université Paris-Saclay, CNRS, AgroParisTech, Ecologie Systématique et Evolution, Île-de-France, Orsay, France.; Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris Sud, Université Paris-Saclay, Île-de-France, Gif-sur-Yvette, France
| | - Fiona Hak
- Université Paris-Saclay, CNRS, AgroParisTech, Ecologie Systématique et Evolution, Île-de-France, Orsay, France.; Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris Sud, Université Paris-Saclay, Île-de-France, Gif-sur-Yvette, France
| | - Alexia Barbry
- CIRI - Centre International de Recherche en Infectiologie, Ecole Normale Supérieure de Lyon, Université Claude Bernard Lyon-1, Rhône-Alpes, Lyon, France; Hospices Civils de Lyon, Institut des Agents Infectieux, Laboratoire de bactériologie, Rhône-Alpes, Lyon, France
| | - Emilie Westeel
- Fondation Mérieux, Emerging Pathogens Laboratory, Rhône-Alpes, Lyon, France
| | - Jean-Luc Berland
- Fondation Mérieux, Emerging Pathogens Laboratory, Rhône-Alpes, Lyon, France
| | - Astrid Engelmann
- Centre Hospitalier Fleyriat, Rhône-Alpes, Bourg-en-Bresse, France
| | - Isabelle Verdier
- Centre Hospitalier Fleyriat, Rhône-Alpes, Bourg-en-Bresse, France
| | - Gérard Lina
- CIRI - Centre International de Recherche en Infectiologie, Ecole Normale Supérieure de Lyon, Université Claude Bernard Lyon-1, Rhône-Alpes, Lyon, France; Hospices Civils de Lyon, Institut des Agents Infectieux, Laboratoire de bactériologie, Rhône-Alpes, Lyon, France; Université Lyon 1, Facultés de Médecine et de Pharmacie de Lyon, Rhône-Alpes, Lyon, France
| | - Florence Ader
- CIRI - Centre International de Recherche en Infectiologie, Ecole Normale Supérieure de Lyon, Université Claude Bernard Lyon-1, Rhône-Alpes, Lyon, France; Hospices Civils de Lyon, Service des Maladies infectieuses et tropicales, Rhône-Alpes, Lyon, France
| | - Stéphane Dray
- Biometrics and Evolutionary Biology Laboratory, CNRS UMR 5558, Université Lyon 1, Rhône-Alpes, Villeurbanne, France
| | - Laurent Jacob
- Biometrics and Evolutionary Biology Laboratory, CNRS UMR 5558, Université Lyon 1, Rhône-Alpes, Villeurbanne, France
| | - François Massol
- UMR 8198 Evo-Eco-Paleo, SPICI Group, University of Lille, Hauts-de-France, Lille, France; CNRS, CHU Lille, Institut Pasteur de Lille, U1019-UMR 9017-CIIL-Center for Infection and Immunity of Lille, University of Lille, Hauts-de-France, Lille, France
| | - Samuel Venner
- Biometrics and Evolutionary Biology Laboratory, CNRS UMR 5558, Université Lyon 1, Rhône-Alpes, Villeurbanne, France
| | - Oana Dumitrescu
- CIRI - Centre International de Recherche en Infectiologie, Ecole Normale Supérieure de Lyon, Université Claude Bernard Lyon-1, Rhône-Alpes, Lyon, France; Hospices Civils de Lyon, Institut des Agents Infectieux, Laboratoire de bactériologie, Rhône-Alpes, Lyon, France; Université Lyon 1, Facultés de Médecine et de Pharmacie de Lyon, Rhône-Alpes, Lyon, France
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12
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Picogram level electrochemical impedimetric immunosensor for monitoring Mycobacterium tuberculosis based on specific and sensitive ESAT-6 monoclonal antibody. Talanta 2022. [DOI: 10.1016/j.talanta.2022.124052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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13
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Asai M, Li Y, Spiropoulos J, Cooley W, Everest DJ, Kendall SL, Martín C, Robertson BD, Langford PR, Newton SM. Galleria mellonella as an infection model for the virulent Mycobacterium tuberculosis H37Rv. Virulence 2022; 13:1543-1557. [PMID: 36052440 PMCID: PMC9481108 DOI: 10.1080/21505594.2022.2119657] [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] [Indexed: 11/26/2022] Open
Abstract
Tuberculosis (TB), caused by Mycobacterium tuberculosis (MTB), is a leading cause of infectious disease mortality. Animal infection models have contributed substantially to our understanding of TB, yet their biological and non-biological limitations are a research bottleneck. There is a need for more ethically acceptable, economical, and reproducible TB infection models capable of mimicking key aspects of disease. Here, we demonstrate and present a basic description of how Galleria mellonella (the greater wax moth, Gm) larvae can be used as a low cost, rapid, and ethically more acceptable model for TB research. This is the first study to infect Gm with the fully virulent MTB H37Rv, the most widely used strain in research. Infection of Gm with MTB resulted in a symptomatic lethal infection, the virulence of which differed from both attenuated Mycobacterium bovis BCG and auxotrophic MTB strains. The Gm-MTB model can also be used for anti-TB drug screening, although CFU enumeration from Gm is necessary for confirmation of mycobacterial load reducing activity of the tested compound. Furthermore, comparative virulence of MTB isogenic mutants can be determined in Gm. However, comparison of mutant phenotypes in Gm against conventional models must consider the limitations of innate immunity. Our findings indicate that Gm will be a practical, valuable, and advantageous additional model to be used alongside existing models to advance tuberculosis research.
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Affiliation(s)
- Masanori Asai
- Section of Paediatric Infectious Diseases, Department of Infectious Disease, Imperial College London, London, UK
| | - Yanwen Li
- Section of Paediatric Infectious Diseases, Department of Infectious Disease, Imperial College London, London, UK
| | - John Spiropoulos
- Department of Pathology, Animal and Plant Health Agency, Addlestone, UK
| | - William Cooley
- Department of Pathology, Animal and Plant Health Agency, Addlestone, UK
| | - David J Everest
- Department of Pathology, Animal and Plant Health Agency, Addlestone, UK
| | - Sharon L Kendall
- Centre for Emerging, Endemic and Exotic Diseases, Pathobiology and Population Sciences, Royal Veterinary College, Hartfield, UK
| | - Carlos Martín
- Department of Microbiology, Facultad de Medicina Universidad de Zaragoza, CIBERES, (ISCIII), Spain
| | - Brian D Robertson
- MRC Centre for Molecular Bacteriology and Infection, Department of Infectious Disease, Imperial College London, UK
| | - Paul R Langford
- Section of Paediatric Infectious Diseases, Department of Infectious Disease, Imperial College London, London, UK
| | - Sandra M Newton
- Section of Paediatric Infectious Diseases, Department of Infectious Disease, Imperial College London, London, UK
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14
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Singh N, Sharma N, Singh P, Pandey M, Ilyas M, Sisodiya L, Choudhury T, Gosain TP, Singh R, Atmakuri K. HupB, a nucleoid-associated protein, is critical for survival of Mycobacterium tuberculosis under host-mediated stresses and for enhanced tolerance to key first-line antibiotics. Front Microbiol 2022; 13:937970. [PMID: 36071978 PMCID: PMC9441915 DOI: 10.3389/fmicb.2022.937970] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2022] [Accepted: 07/12/2022] [Indexed: 11/30/2022] Open
Abstract
To survive and establish its niche, Mycobacterium tuberculosis (Mtb) engages in a steady battle against an array of host defenses and a barrage of antibiotics. Here, we demonstrate that Mtb employs HupB, a nucleoid-associated protein (NAP) as its key player to simultaneously battle and survive in these two stress-inducing fronts. Typically, NAPs are key to bacterial survival under a wide array of environmental or host-mediated stresses. Here, we report that for Mtb to survive under different macrophage-induced assaults including acidic pH, nutrient depletion, oxidative and nitrosative stresses, HupB presence is critical. As expected, the hupB knockout mutant is highly sensitive to these host-mediated stresses. Furthermore, Mtb aptly modulates HupB protein levels to overcome these stresses. We also report that HupB aids Mtb to gain tolerance to high levels of rifampicin (RIF) and isoniazid (INH) exposure. Loss of hupB makes Mtb highly susceptible to even short exposures to reduced amounts of RIF and INH. Overexpressing hupB in Mtb or complementing hupB in the hupB knockout mutant triggers enhanced survival of Mtb under these stresses. We also find that upon loss of hupB, Mtb significantly enhances the permeability of its cell wall by modulating the levels of several surface lipids including phthiocerol dimycocerosates (PDIMs), thus possibly influencing overall susceptibility to host-mediated stresses. Loss of hupB also downregulates efflux pump expression possibly influencing increased susceptibility to INH and RIF. Finally, we find that therapeutic targeting of HupB with SD1, a known small molecule inhibitor, significantly enhances Mtb susceptibility to INH and THP-1 macrophages and significantly reduces MIC to INH. Thus, our data strongly indicate that HupB is a highly promising therapeutic target especially for potential combinatorial shortened therapy with reduced INH and RIF doses.
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Affiliation(s)
- Niti Singh
- Infection and Immunology Group, Translational Health Science and Technology Institute, Faridabad, Haryana, India
- Manipal University, Manipal, Karnataka, India
| | - Nishant Sharma
- Infection and Immunology Group, Translational Health Science and Technology Institute, Faridabad, Haryana, India
| | - Padam Singh
- Infection and Immunology Group, Translational Health Science and Technology Institute, Faridabad, Haryana, India
| | - Manitosh Pandey
- Infection and Immunology Group, Translational Health Science and Technology Institute, Faridabad, Haryana, India
- Department of Life Sciences, ITM University, Gwalior, Madhya Pradesh, India
| | - Mohd Ilyas
- Infection and Immunology Group, Translational Health Science and Technology Institute, Faridabad, Haryana, India
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Lovely Sisodiya
- Infection and Immunology Group, Translational Health Science and Technology Institute, Faridabad, Haryana, India
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Tejaswini Choudhury
- Infection and Immunology Group, Translational Health Science and Technology Institute, Faridabad, Haryana, India
| | - Tannu Priya Gosain
- Infection and Immunology Group, Translational Health Science and Technology Institute, Faridabad, Haryana, India
- School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Ramandeep Singh
- Infection and Immunology Group, Translational Health Science and Technology Institute, Faridabad, Haryana, India
| | - Krishnamohan Atmakuri
- Infection and Immunology Group, Translational Health Science and Technology Institute, Faridabad, Haryana, India
- *Correspondence: Krishnamohan Atmakuri
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15
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Molecular Connectivity between Extracytoplasmic Sigma Factors and PhoP Accounts for Coupled Mycobacterial Stress Response. J Bacteriol 2022; 204:e0011022. [PMID: 35608366 DOI: 10.1128/jb.00110-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Mycobacterium tuberculosis encounters numerous stress conditions within the host, but how it is able to mount a coupled stress response remains unknown. Growing evidence suggests that under acidic pH, M. tuberculosis modulates redox homeostasis. In an attempt to dissect the mechanistic details of responses to multiple stress conditions, here we studied the significance of connectivity of extracytoplasmic sigma factors with PhoP. We show that PhoP impacts the mycothiol redox state, and the H37Rv ΔphoP deletion mutant strain displays a significantly higher susceptibility to redox stress than the wild-type bacilli. To probe how the two regulators PhoP and redox-active sigma factor SigH contribute to redox homeostasis, we show that SigH controls expression of redox-active thioredoxin genes, a major mycobacterial antioxidant system, and under redox stress, SigH, but not PhoP, is recruited at the target promoters. Consistent with these results, interaction between PhoP and SigH fails to impact redox-dependent gene expression. This is in striking contrast to our previous results showing PhoP-dependent SigE recruitment within acid-inducible mycobacterial promoters to maintain pH homeostasis. Our subsequent results demonstrate reduced PhoP-SigH interaction in the presence of diamide and enhanced PhoP-SigE interaction under low pH. These contrasting results uncover the underlying mechanism of the mycobacterial adaptive program, coupling low pH with maintenance of redox homeostasis. IMPORTANCE M. tuberculosis encounters reductive stress under acidic pH. To investigate the mechanism of coupled stress response, we show that PhoP plays a major role in mycobacterial redox stress response. We observed a strong correlation of phoP-dependent redox-active expression of thioredoxin genes, a major mycobacterial antioxidant system. Further probing of functioning of regulators revealed that while PhoP controls pH homeostasis via its interaction with SigE, direct recruitment of SigH, but not PhoP-SigH interaction, controls expression of thioredoxin genes. These strikingly contrasting results showing enhanced PhoP-SigE interaction under acidic pH and reduced PhoP-SigH interaction under redox conditions uncover the underlying novel mechanism of the mycobacterial adaptive program, coupling low pH with maintenance of redox homeostasis.
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16
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García EA, Blanco FC, Bigi F. H65 fusion protein fails to improve the protection of a rationally attenuated live vaccine candidate against bovine tuberculosis in a mouse model of tuberculosis. Int J Mycobacteriol 2021; 10:411-413. [PMID: 34916460 DOI: 10.4103/ijmy.ijmy_201_21] [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: 11/04/2022] Open
Abstract
Background The fusion protein H65, composed of Mycobacterium tuberculosis (TB) ESX-secreted antigens, has improved the bacillus Calmette-Guerin-induced immune protection in a mouse model of bovine TB when formulated in the liposomal adjuvant CAF01. In this study, we aimed to evaluate the protective efficacy of an attenuated Mycobacterium bovis strain - a mutant in mce2 and phoP genes - combined with H65+CAF01 immunization. We evaluated the protection of MbΔmce2-phoP alone or combined with H65+CAF01 against M. bovis challenge in mice. Methods Groups of BALBc mice were inoculated with the vaccine candidates or phosphate buffered saline (PBS), and 6 weeks after the last immunization, the animals were aerogenically challenged with virulent M. bovis. Bacterial load in organs was counted after 45 days of the challenge. One-way analysis of variance and Bonferroni's posttest were used for statistical analysis. Results All vaccinated mice showed reduced bacterial loads in lungs compared to unvaccinated animals. However, the protection level was similar between vaccinated groups. Conclusions The MbΔmce2-phoP strain combined with three doses of H65+CAF01 induced equivalent protection than the MbΔmce2-phoP strain alone. Thus, the use of combined vaccination strategies requires a careful analysis of the potential interactions of each of their components with the host's immune system.
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Affiliation(s)
- Elizabeth A García
- Instituto de Agrobiotecnologia y Biologia Molecular, Institute of Agrobiotechnology and Molecular Biology, (IABIMO) INTA-CONICET; Laboratorio de Tuberculosis Bovina, Bovine Tuberculosis Laboratory, Instituto de Biotecnología, CICVyA, Instituto Nacional de Tecnología Agropecuaria, Institute of Biotechnology, National Institute of Agricultural Technology, Buenos Aires, Argentina
| | - Federico C Blanco
- Instituto de Agrobiotecnologia y Biologia Molecular, Institute of Agrobiotechnology and Molecular Biology, (IABIMO) INTA-CONICET; Laboratorio de Tuberculosis Bovina, Bovine Tuberculosis Laboratory, Instituto de Biotecnología, CICVyA, Instituto Nacional de Tecnología Agropecuaria, Institute of Biotechnology, National Institute of Agricultural Technology, Buenos Aires, Argentina
| | - Fabiana Bigi
- Instituto de Agrobiotecnologia y Biologia Molecular, Institute of Agrobiotechnology and Molecular Biology, (IABIMO) INTA-CONICET; Laboratorio de Tuberculosis Bovina, Bovine Tuberculosis Laboratory, Instituto de Biotecnología, CICVyA, Instituto Nacional de Tecnología Agropecuaria, Institute of Biotechnology, National Institute of Agricultural Technology, Buenos Aires, Argentina
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17
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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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18
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Modeling Tubercular ESX-1 Secretion Using Mycobacterium marinum. Microbiol Mol Biol Rev 2020; 84:84/4/e00082-19. [DOI: 10.1128/mmbr.00082-19] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Pathogenic mycobacteria cause chronic and acute diseases ranging from human tuberculosis (TB) to nontubercular infections.
Mycobacterium tuberculosis
causes both acute and chronic human tuberculosis. Environmentally acquired nontubercular mycobacteria (NTM) cause chronic disease in humans and animals. Not surprisingly, NTM and
M. tuberculosis
often use shared molecular mechanisms to survive within the host. The ESX-1 system is a specialized secretion system that is essential for virulence and is functionally conserved between
M. tuberculosis
and
Mycobacterium marinum
.
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19
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Mavi PS, Singh S, Kumar A. Reductive Stress: New Insights in Physiology and Drug Tolerance of Mycobacterium. Antioxid Redox Signal 2020; 32:1348-1366. [PMID: 31621379 DOI: 10.1089/ars.2019.7867] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Significance:Mycobacterium tuberculosis (Mtb) encounters reductive stress during its infection cycle. Notably, host-generated protective responses, such as acidic pH inside phagosomes and lysosomes, exposure to glutathione in alveolar hypophase (i.e., a thin liquid lining consisting of surfactant and proteins in the alveolus), and hypoxic environments inside granulomas are associated with the accumulation of reduced cofactors, such as nicotinamide adenine dinucleotide (reduced form), nicotinamide adenine dinucleotide phosphate, flavin adenine dinucleotide (reduced form), and nonprotein thiols (e.g., mycothiol), leading to reductive stress in Mtb cells. Dissipation of this reductive stress is important for survival of the bacterium. If reductive stress is not dissipated, it leads to generation of reactive oxygen species, which may be fatal for the cells. Recent Advances: This review focuses on mechanisms utilized by mycobacteria to sense and respond to reductive stress. Importantly, exposure of Mtb cells to reductive stress leads to growth inhibition, altered metabolism, modulation of virulence, and drug tolerance. Mtb is equipped with thiol buffering systems of mycothiol and ergothioneine to protect itself from various redox stresses. These systems are complemented by thioredoxin and thioredoxin reductase (TR) systems for maintaining cellular redox homeostasis. A diverse array of sensors is used by Mycobacterium for monitoring its intracellular redox status. Upon sensing reductive stress, Mtb uses a flexible and robust metabolic system for its dissipation. Branched electron transport chain allows Mycobacterium to function with different terminal electron acceptors and modulate proton motive force to fulfill energy requirements under diverse scenarios. Interestingly, Mtb utilizes variations in the tricarboxylic cycle and a number of dehydrogenases to dissipate reductive stress. Upon prolonged exposure to reductive stress, Mtb utilizes biosynthesis of storage and virulence lipids as a dissipative mechanism. Critical Issues: The mechanisms utilized by Mycobacterium for sensing and tackling reductive stress are not well characterized. Future Directions: The precise role of thiol buffering and TR systems in neutralizing reductive stress is not well defined. Genetic systems that respond to metabolic reductive stress and thiol reductive stress need to be mapped. Genetic screens could aid in identification of such systems. Given that management of reductive stress is critical for both actively replicating and persister mycobacteria, an improved understanding of the mechanisms used by mycobacteria for dissipation of reductive stress may lead to identification of vulnerable choke points that could be targeted for killing Mtb in vivo.
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Affiliation(s)
- Parminder Singh Mavi
- Institute of Microbial Technology, Council of Scientific and Industrial Research, Chandigarh, India
| | - Shweta Singh
- Institute of Microbial Technology, Council of Scientific and Industrial Research, Chandigarh, India
| | - Ashwani Kumar
- Institute of Microbial Technology, Council of Scientific and Industrial Research, Chandigarh, India.,Academy of Scientific and Innovative Research, Ghaziabad, India
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20
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Host-Directed Therapies and Anti-Virulence Compounds to Address Anti-Microbial Resistant Tuberculosis Infection. APPLIED SCIENCES-BASEL 2020. [DOI: 10.3390/app10082688] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Despite global efforts to contain tuberculosis (TB), the disease remains a leading cause of morbidity and mortality worldwide, further exacerbated by the increased resistance to antibiotics displayed by the tubercle bacillus Mycobacterium tuberculosis. In order to treat drug-resistant TB, alternative or complementary approaches to standard anti-TB regimens are being explored. An area of active research is represented by host-directed therapies which aim to modulate the host immune response by mitigating inflammation and by promoting the antimicrobial activity of immune cells. Additionally, compounds that reduce the virulence of M. tuberculosis, for instance by targeting the major virulence factor ESX-1, are being given increased attention by the TB research community. This review article summarizes the current state of the art in the development of these emerging therapies against TB.
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21
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Guan Q, Ummels R, Ben-Rached F, Alzahid Y, Amini MS, Adroub SA, van Ingen J, Bitter W, Abdallah AM, Pain A. Comparative Genomic and Transcriptomic Analyses of Mycobacterium kansasii Subtypes Provide New Insights Into Their Pathogenicity and Taxonomy. Front Cell Infect Microbiol 2020; 10:122. [PMID: 32266172 PMCID: PMC7105574 DOI: 10.3389/fcimb.2020.00122] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Accepted: 03/04/2020] [Indexed: 12/21/2022] Open
Abstract
Mycobacterium kansasii is an important opportunistic pathogen of humans and has a close phylogenetic relationship with Mycobacterium tuberculosis. Seven subtypes (I-VII) have been identified using molecular biology approaches, of which subtype I is the most frequent causative agent of human disease. To investigate the genotypes and pathogenic components of M. kansasii, we sequenced and compared the complete base-perfect genomes of different M. kansasii subtypes. Our findings support the proposition that M. kansasii "subtypes" I-VI, whose assemblies are currently available, should be considered as different species. Furthermore, we identified the exclusive presence of the espACD operon in M. kansasii subtype I, and we confirmed its role in the pathogenicity of M. kansasii in a cell infection model. The espACD operon is exclusively present in mycobacterial species that induce phagosomal rupture in host phagocytes and is known to be a major determinant of ESX1-mediated virulence in pathogenic mycobacteria. Comparative transcriptome analysis of the M. kansasii I-V strains identified genes potentially associated with virulence. Using a comparative genomics approach, we designed primers for PCR genotyping of M. kansasii subtypes I-V and tested their efficacy using clinically relevant strains of M. kansasii.
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Affiliation(s)
- Qingtian Guan
- Pathogen Genomics Laboratory, BESE Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - Roy Ummels
- Department of Medical Microbiology and Infection Control, Amsterdam University Medical Centers, Amsterdam, Netherlands
| | - Fathia Ben-Rached
- Pathogen Genomics Laboratory, BESE Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - Yara Alzahid
- Pathogen Genomics Laboratory, BESE Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - Mohammad S. Amini
- Pathogen Genomics Laboratory, BESE Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - Sabir A. Adroub
- Pathogen Genomics Laboratory, BESE Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
| | - Jakko van Ingen
- Department of Medical Microbiology, Radboud UMC Center for Infectious Diseases, Radboud University Medical Center, Nijmegen, Netherlands
| | - Wilbert Bitter
- Department of Medical Microbiology and Infection Control, Amsterdam University Medical Centers, Amsterdam, Netherlands
| | - Abdallah M. Abdallah
- Pathogen Genomics Laboratory, BESE Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
- Department of Basic Medical Sciences, College of Medicine, QU Health, Qatar University, Doha, Qatar
| | - Arnab Pain
- Pathogen Genomics Laboratory, BESE Division, King Abdullah University of Science and Technology (KAUST), Thuwal, Saudi Arabia
- Center for Zoonosis Control, Global Institution for Collaborative Research and Education (GI-CoRE), Hokkaido University, Sapporo, Japan
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22
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Metabolic Switching of Mycobacterium tuberculosis during Hypoxia Is Controlled by the Virulence Regulator PhoP. J Bacteriol 2020; 202:JB.00705-19. [PMID: 31932312 DOI: 10.1128/jb.00705-19] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Accepted: 01/06/2020] [Indexed: 11/20/2022] Open
Abstract
Mycobacterium tuberculosis retains the ability to establish an asymptomatic latent infection. A fundamental question in mycobacterial physiology is to understand the mechanisms involved in hypoxic stress, a critical player in persistence. Here, we show that the virulence regulator PhoP responds to hypoxia, the dormancy signal, and effectively integrates hypoxia with nitrogen metabolism. We also provide evidence to demonstrate that both under nitrogen limiting conditions and during hypoxia, phoP locus controls key genes involved in nitrogen metabolism. Consistently, under hypoxia a ΔphoP strain shows growth attenuation even with surplus nitrogen, the alternate electron acceptor, and complementation of the mutant restores bacterial growth. Together, our observations provide new biological insights into the role of PhoP in integrating nitrogen metabolism with hypoxia by the assistance of the hypoxia regulator DosR. The results have significant implications on the mechanism of intracellular survival and growth of the tubercle bacilli under a hypoxic environment within the phagosome.IMPORTANCE M. tuberculosis retains the unique ability to establish an asymptomatic latent infection. To understand the mechanisms involved in hypoxic stress which play a critical role in persistence, we show that the virulence regulator PhoP is linked to hypoxia, the dormancy signal. In keeping with this, phoP was shown to play a major role in M. tuberculosis growth under hypoxia even in the presence of surplus nitrogen, the alternate electron acceptor. Our results showing regulation of hypoxia-responsive genes provide new biological insights into role of the virulence regulator in metabolic switching by sensing hypoxia and integrating nitrogen metabolism with hypoxia by the assistance of the hypoxia regulator DosR.
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24
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Functioning of Mycobacterial Heat Shock Repressors Requires the Master Virulence Regulator PhoP. J Bacteriol 2019; 201:JB.00013-19. [PMID: 30962357 DOI: 10.1128/jb.00013-19] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2019] [Accepted: 04/01/2019] [Indexed: 01/16/2023] Open
Abstract
A hallmark feature of Mycobacterium tuberculosis pathogenesis lies in the ability of the pathogen to survive within macrophages under a stressful environment. Thus, coordinated regulation of stress proteins is critically important for an effective adaptive response of M. tuberculosis, the failure of which results in elevated immune recognition of the tubercle bacilli with reduced survival during chronic infections. Here, we show that virulence regulator PhoP impacts the global regulation of heat shock proteins, which protect M. tuberculosis against stress generated by macrophages during infection. Our results identify that in addition to classical DNA-protein interactions, newly discovered protein-protein interactions control complex mechanisms of expression of heat shock proteins, an essential pathogenic determinant of M. tuberculosis While the C-terminal domain of PhoP binds to its target promoters, the N-terminal domain of the regulator interacts with the C-terminal end of the heat shock repressors. Remarkably, our findings delineate a regulatory pathway which involves three major transcription factors, PhoP, HspR, and HrcA, that control in vivo recruitment of the regulators within the target genes and regulate stress-specific expression of heat shock proteins via protein-protein interactions. The results have implications on the mechanism of regulation of PhoP-dependent stress response in M. tuberculosis IMPORTANCE The regulation of heat shock proteins which protect M. tuberculosis against stress generated by macrophages during infection is poorly understood. In this study, we show that PhoP, a virulence regulator of the tubercle bacilli, controls heat shock-responsive genes, an essential pathogenic determinant of M. tuberculosis Our results unravel that in addition to classical DNA-protein interactions, complex mechanisms of regulation of heat shock-responsive genes occur through multiple protein-protein interactions. Together, these findings delineate a fundamental regulatory pathway where transcription factors PhoP, HspR, and HrcA interact with each other to control stress-specific expression of heat shock proteins.
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Novel MprA binding motifs in the phoP regulatory region in Mycobacterium tuberculosis. Tuberculosis (Edinb) 2018; 112:62-68. [PMID: 30205970 DOI: 10.1016/j.tube.2018.08.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 07/31/2018] [Accepted: 08/02/2018] [Indexed: 11/20/2022]
Abstract
MprAB and PhoPR are important two-component systems (TCSs) in Mycobacterium tuberculosis, and both regulate EspR, a key regulator of the ESX-1 secretion system. Although previous studies suggest that the response regulator PhoP does not directly regulate mprA, the interplay between MprAB and PhoPR remains unclear. In this study, we found that the response regulator MprA can bind to the phoP promoter. Four repeat motifs, D1-D4, constituting two predicted binding sites, were located in the region protected by MprA in DNA footprinting. D1-D4 lack the reported conserved MprA binding sequences, indicating that MprA can recognize a greater range of target sites. Interestingly, D1-D2 overlap a previously reported PhoP binding site, and mutation of D1-D2 inhibited PhoP binding, whereas the D3-D4 site, but not the D1-D2 site, was required for MprA binding. EMSA assays also suggest that MprA and PhoP compete to bind to the phoP promoter. The results of the transcriptional and western blot assays are consistent with a model in which MprA positively controls the phoP expression, which in turn upregulates the expression of espR. These findings reveal complex regulation of a major mycobacterial TCS by dual TCSs.
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Chawla M, Mishra S, Anand K, Parikh P, Mehta M, Vij M, Verma T, Singh P, Jakkala K, Verma HN, AjitKumar P, Ganguli M, Narain Seshasayee AS, Singh A. Redox-dependent condensation of the mycobacterial nucleoid by WhiB4. Redox Biol 2018; 19:116-133. [PMID: 30149290 PMCID: PMC6111044 DOI: 10.1016/j.redox.2018.08.006] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Revised: 08/02/2018] [Accepted: 08/11/2018] [Indexed: 12/22/2022] Open
Abstract
Oxidative stress response in bacteria is mediated through coordination between the regulators of oxidant-remediation systems (e.g. OxyR, SoxR) and nucleoid condensation (e.g. Dps, Fis). However, these genetic factors are either absent or rendered non-functional in the human pathogen Mycobacterium tuberculosis (Mtb). Therefore, how Mtb organizes genome architecture and regulates gene expression to counterbalance oxidative imbalance is unknown. Here, we report that an intracellular redox-sensor, WhiB4, dynamically links genome condensation and oxidative stress response in Mtb. Disruption of WhiB4 affects the expression of genes involved in maintaining redox homeostasis, central metabolism, and respiration under oxidative stress. Notably, disulfide-linked oligomerization of WhiB4 in response to oxidative stress activates the protein’s ability to condense DNA. Further, overexpression of WhiB4 led to hypercondensation of nucleoids, redox imbalance and increased susceptibility to oxidative stress, whereas WhiB4 disruption reversed this effect. In accordance with the findings in vitro, ChIP-Seq data demonstrated non-specific binding of WhiB4 to GC-rich regions of the Mtb genome. Lastly, data indicate that WhiB4 deletion affected the expression of ~ 30% of genes preferentially bound by the protein, suggesting both direct and indirect effects on gene expression. We propose that WhiB4 structurally couples Mtb’s response to oxidative stress with genome organization and transcription. Genome condensation is involved in the management of oxidative stress in bacteria. A relation between the genome condensation and oxidative stress is unclear in Mtb. A redox sensor WhiB4 calibrates genome-condensation and antioxidants in Mtb. Over-expression of WhiB4 hyper-condensed genome and induced killing by oxidants. WhiB4 deficiency delayed genome condensation and promoted oxidative stress survival.
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Affiliation(s)
- Manbeena Chawla
- Department of Microbiology and Cell Biology, Centre for Infectious Disease Research, Indian Institute of Science, Bangalore 560012, India
| | - Saurabh Mishra
- Department of Microbiology and Cell Biology, Centre for Infectious Disease Research, Indian Institute of Science, Bangalore 560012, India
| | - Kushi Anand
- Department of Microbiology and Cell Biology, Centre for Infectious Disease Research, Indian Institute of Science, Bangalore 560012, India
| | - Pankti Parikh
- Department of Microbiology and Cell Biology, Centre for Infectious Disease Research, Indian Institute of Science, Bangalore 560012, India
| | - Mansi Mehta
- Department of Microbiology and Cell Biology, Centre for Infectious Disease Research, Indian Institute of Science, Bangalore 560012, India
| | - Manika Vij
- Department of Structural Biology, CSIR-Institute of Genomics and Integrative Biology, South Campus, Mathura Road, New Delhi 110020, India; Academy of Scientific and Innovative Research (AcSIR), Anusandhan Bhawan, 2 Rafi Marg, New Delhi 110001, India
| | - Taru Verma
- Department of Microbiology and Cell Biology, Centre for Infectious Disease Research, Indian Institute of Science, Bangalore 560012, India; Centre for BioSystems Science and Engineering (BSSE), Indian Institute of Science, Bangalore 560012, India
| | - Parul Singh
- National Centre for Biological Science, Bangalore 560065, India; SASTRA University, Thanjavur 613401, Tamil Nadu, India
| | - Kishor Jakkala
- Department of Microbiology and Cell Biology, Centre for Infectious Disease Research, Indian Institute of Science, Bangalore 560012, India
| | - H N Verma
- Jaipur National University, Jagatpura, Jaipur 302017, India
| | - Parthasarathi AjitKumar
- Department of Microbiology and Cell Biology, Centre for Infectious Disease Research, Indian Institute of Science, Bangalore 560012, India
| | - Munia Ganguli
- Department of Structural Biology, CSIR-Institute of Genomics and Integrative Biology, South Campus, Mathura Road, New Delhi 110020, India; Academy of Scientific and Innovative Research (AcSIR), Anusandhan Bhawan, 2 Rafi Marg, New Delhi 110001, India
| | | | - Amit Singh
- Department of Microbiology and Cell Biology, Centre for Infectious Disease Research, Indian Institute of Science, Bangalore 560012, India.
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Kundu M. The role of two-component systems in the physiology of Mycobacterium tuberculosis. IUBMB Life 2018; 70:710-717. [PMID: 29885211 DOI: 10.1002/iub.1872] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Accepted: 04/22/2018] [Indexed: 12/14/2022]
Abstract
Tuberculosis is a global health problem, with a third of the world's population infected with the bacillus, Mycobacterium tuberculosis. The problem is exacerbated by the emergence of multidrug resistant and extensively drug resistant strains. The search for new drug targets is therefore a priority for researchers in the field. The two-component systems (TCSs) are central to the ability of the bacterium to sense and to respond appropriately to its environment. Here we summarize current knowledge on the paired TCSs of M. tuberculosis. We discuss what is currently understood regarding the signals to which each of the sensor kinases responds, and the regulons of each of the cognate response regulators. We also discuss what is known regarding attempts to inhibit the TCSs by small molecules and project their potential as pharmacological targets for the development of novel antimycobacterial agents. © 2018 IUBMB Life, 70(8):710-717, 2018.
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Gago G, Diacovich L, Gramajo H. Lipid metabolism and its implication in mycobacteria-host interaction. Curr Opin Microbiol 2018; 41:36-42. [PMID: 29190491 PMCID: PMC5862736 DOI: 10.1016/j.mib.2017.11.020] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2017] [Revised: 11/06/2017] [Accepted: 11/07/2017] [Indexed: 12/16/2022]
Abstract
The complex lipids present in the cell wall of Mycobacterium tuberculosis (Mtb) act as major effector molecules that actively interact with the host, modulating its metabolism and stimulating the immune response, which in turn affects the physiology of both, the host cell and the bacilli. Lipids from the host are also nutrient sources for the pathogen and define the fate of the infection by modulating lipid homeostasis. Although new technologies and experimental models of infection have greatly helped understanding the different aspects of the host-pathogen interactions at the lipid level, the impact of this interaction in the Mtb lipid regulation is still incipient, mainly because of the low background knowledge in this area of research.
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Affiliation(s)
- Gabriela Gago
- Laboratory of Physiology and Genetics of Actinomycetes, Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Lautaro Diacovich
- Laboratory of Physiology and Genetics of Actinomycetes, Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Hugo Gramajo
- Laboratory of Physiology and Genetics of Actinomycetes, Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina.
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Zondervan NA, van Dam JCJ, Schaap PJ, Martins Dos Santos VAP, Suarez-Diez M. Regulation of Three Virulence Strategies of Mycobacterium tuberculosis: A Success Story. Int J Mol Sci 2018; 19:E347. [PMID: 29364195 PMCID: PMC5855569 DOI: 10.3390/ijms19020347] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2017] [Revised: 01/19/2018] [Accepted: 01/21/2018] [Indexed: 12/28/2022] Open
Abstract
Tuberculosis remains one of the deadliest diseases. Emergence of drug-resistant and multidrug-resistant M. tuberculosis strains makes treating tuberculosis increasingly challenging. In order to develop novel intervention strategies, detailed understanding of the molecular mechanisms behind the success of this pathogen is required. Here, we review recent literature to provide a systems level overview of the molecular and cellular components involved in divalent metal homeostasis and their role in regulating the three main virulence strategies of M. tuberculosis: immune modulation, dormancy and phagosomal rupture. We provide a visual and modular overview of these components and their regulation. Our analysis identified a single regulatory cascade for these three virulence strategies that respond to limited availability of divalent metals in the phagosome.
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Affiliation(s)
- Niels A Zondervan
- Laboratory of Systems and Synthetic Biology, Wageningen University & Research, Stippeneng 4, 6708 WE Wageningen, The Netherlands.
| | - Jesse C J van Dam
- Laboratory of Systems and Synthetic Biology, Wageningen University & Research, Stippeneng 4, 6708 WE Wageningen, The Netherlands.
| | - Peter J Schaap
- Laboratory of Systems and Synthetic Biology, Wageningen University & Research, Stippeneng 4, 6708 WE Wageningen, The Netherlands.
| | - Vitor A P Martins Dos Santos
- Laboratory of Systems and Synthetic Biology, Wageningen University & Research, Stippeneng 4, 6708 WE Wageningen, The Netherlands.
- LifeGlimmer GmbH, Markelstrasse 38, 12163 Berlin, Germany.
| | - Maria Suarez-Diez
- Laboratory of Systems and Synthetic Biology, Wageningen University & Research, Stippeneng 4, 6708 WE Wageningen, The Netherlands.
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Kriel NL, Gallant J, van Wyk N, van Helden P, Sampson SL, Warren RM, Williams MJ. Mycobacterial nucleoid associated proteins: An added dimension in gene regulation. Tuberculosis (Edinb) 2018. [DOI: 10.1016/j.tube.2017.12.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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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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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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