1
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Cui Y, Dang G, Wang H, Tang Y, Lv M, Zang X, Cai Z, Cui Z, Cao J, Liu S, Song N. DosR Regulates the Transcription of the Arginine Biosynthesis Gene Cluster by Binding to the Regulatory Sequences in Mycobacterium bovis Bacille Calmette-Guerin. DNA Cell Biol 2022; 41:1063-1074. [DOI: 10.1089/dna.2022.0282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Affiliation(s)
- Yingying Cui
- State Key Laboratory of Veterinary Biotechnology, Division of Bacterial Diseases, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, P.R. China
| | - Guanghui Dang
- State Key Laboratory of Veterinary Biotechnology, Division of Bacterial Diseases, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, P.R. China
| | - Hui Wang
- State Key Laboratory of Veterinary Biotechnology, Division of Bacterial Diseases, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, P.R. China
| | - Yiyi Tang
- State Key Laboratory of Veterinary Biotechnology, Division of Bacterial Diseases, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, P.R. China
| | - Mingyue Lv
- State Key Laboratory of Veterinary Biotechnology, Division of Bacterial Diseases, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, P.R. China
| | - Xinxin Zang
- State Key Laboratory of Veterinary Biotechnology, Division of Bacterial Diseases, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, P.R. China
| | - Zhuming Cai
- State Key Laboratory of Veterinary Biotechnology, Division of Bacterial Diseases, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, P.R. China
| | - Ziyin Cui
- State Key Laboratory of Veterinary Biotechnology, Division of Bacterial Diseases, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, P.R. China
| | - Jun Cao
- State Key Laboratory of Veterinary Biotechnology, Division of Bacterial Diseases, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, P.R. China
| | - Siguo Liu
- State Key Laboratory of Veterinary Biotechnology, Division of Bacterial Diseases, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, P.R. China
| | - Ningning Song
- State Key Laboratory of Veterinary Biotechnology, Division of Bacterial Diseases, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, P.R. China
- Bioengineering Department, School of Life Science and Technology, Weifang Medical University, Weifang, P.R. China
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2
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Gautam US, Asrican R, Sempowski GD. Targeted dose delivery of Mycobacterium tuberculosis in mice using silicon antifoaming agent via aerosol exposure system. PLoS One 2022; 17:e0276130. [PMID: 36228009 PMCID: PMC9560519 DOI: 10.1371/journal.pone.0276130] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Accepted: 09/29/2022] [Indexed: 11/09/2022] Open
Abstract
Mycobacterium tuberculosis (Mtb) is an intracellular pathogen that forms aggregates (clumps) on solid agar plates and in liquid media. Detergents such as Tween 80/Tyloxapol are considered the gold standard to disrupt clump formation in Mtb cultures. The presence of detergent, however, may generate foam and hinder Mtb aerosolization thus requiring addition of an antifoam agent for optimal Mtb aerosol-based procedures. Aerosol inhalation can be technically challenging, in particular to achieve a reproducible inhaled target dose. In this study, the impact of an antifoam, the silicon antifoaming agent (SAF), on Mtb aerosolization and whole-body mouse aerosol infection was investigated. A comparative study using SAF in a liquid suspension containing Mycobacterium bovis BCG (M. bovis BCG) or Mtb H37Rv did not cause any adverse effect on bacterial viability. Incorporation of SAF during mycobacteria inhalation procedures revealed that aerosolized mycobacterial strains were maintained under controlled environmental conditions such as humidity, temperature, pressure, and airflow inside the aerosol chamber. In addition, environmental factors and spray factors were not affected by the presence of SAF in mycobacterial cultures during aerosolization. Spray factor was significantly less during aerosol procedures with a low-input dose of mycobacteria in comparison to high-dose, as predicted. The mycobacterial load recovered in the biosampler (AGI) was ~2–3 logs lower than nebulizer or input bacterial load. A consistent Mtb bacillary load determined in mouse lungs indicates that SAF does not affect mycobacteria aerosolization during the aerosol generation process. These data confirmed that 1) SAF prevents formation of excessive foam during aerosolization, 2) SAF had no negative impact on mycobacterial viability within aerosol droplets, 3) Mtb droplets within aerosol-generated particles are well within the range required for reaching and depositing deep into lung tissue, and 4) SAF had no negative impact on achieving a target dose in mice exposed to Mtb aerosol.
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Affiliation(s)
- Uma Shankar Gautam
- Duke Human Vaccine Institute, Duke University School of Medicine, Durham, North Carolina, United States of America
- * E-mail: (USG); (GDS)
| | - Rosemarie Asrican
- Duke Human Vaccine Institute, Duke University School of Medicine, Durham, North Carolina, United States of America
| | - Gregory D. Sempowski
- Duke Human Vaccine Institute, Duke University School of Medicine, Durham, North Carolina, United States of America
- Departments of Medicine and Pathology, Duke University School of Medicine, Durham, North Carolina, United States of America
- * E-mail: (USG); (GDS)
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3
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Robbe-Saule M, Foulon M, Poncin I, Esnault L, Varet H, Legendre R, Besnard A, Grzegorzewicz AE, Jackson M, Canaan S, Marsollier L, Marion E. Transcriptional adaptation of Mycobacterium ulcerans in an original mouse model: New insights into the regulation of mycolactone. Virulence 2021; 12:1438-1451. [PMID: 34107844 PMCID: PMC8204960 DOI: 10.1080/21505594.2021.1929749] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Mycobacterium ulcerans is the causal agent of Buruli ulcer, a chronic infectious disease and the third most common mycobacterial disease worldwide. Without early treatment, M. ulcerans provokes massive skin ulcers, caused by the mycolactone toxin, its main virulence factor. However, spontaneous healing may occur in Buruli ulcer patients several months or years after the disease onset. We have shown, in an original mouse model, that bacterial load remains high and viable in spontaneously healed tissues, with a switch of M. ulcerans to low levels of mycolactone production, adapting its strategy to survive in such a hostile environment. This original model offers the possibility to investigate the regulation of mycolactone production, by using an RNA-seq strategy to study bacterial adaptation during mouse infection. Pathway analysis and characterization of the tissue environment showed that the bacillus adapted to its new environment by modifying its metabolic activity and switching nutrient sources. Thus, M. ulcerans ensures its survival in healing tissues by reducing its secondary metabolism, leading to an inhibition of mycolactone synthesis. These findings shed new light on mycolactone regulation and pave the way for new therapeutic strategies.
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Affiliation(s)
| | | | | | | | - Hugo Varet
- Plate-forme Transcriptome Et Epigenome, Biomics, Centre De Ressources Et Recherches Technologiques (C2RT), Institut Pasteur, Paris, France.,Hub De Bioinformatique Et Biostatistique - Département Biologie Computationnelle, Institut Pasteur, Paris, France
| | - Rachel Legendre
- Plate-forme Transcriptome Et Epigenome, Biomics, Centre De Ressources Et Recherches Technologiques (C2RT), Institut Pasteur, Paris, France.,Hub De Bioinformatique Et Biostatistique - Département Biologie Computationnelle, Institut Pasteur, Paris, France
| | | | - Anna E Grzegorzewicz
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, United States
| | - Mary Jackson
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, United States
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4
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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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5
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Gautam US, Mehra S, Kumari P, Alvarez X, Niu T, Tyagi JS, Kaushal D. Mycobacterium tuberculosis sensor kinase DosS modulates the autophagosome in a DosR-independent manner. Commun Biol 2019; 2:349. [PMID: 31552302 PMCID: PMC6754383 DOI: 10.1038/s42003-019-0594-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2018] [Accepted: 09/03/2019] [Indexed: 01/03/2023] Open
Abstract
Dormancy is a key characteristic of the intracellular life-cycle of Mtb. The importance of sensor kinase DosS in mycobacteria are attributed in part to our current findings that DosS is required for both persistence and full virulence of Mtb. Here we show that DosS is also required for optimal replication in macrophages and involved in the suppression of TNF-α and autophagy pathways. Silencing of these pathways during the infection process restored full virulence in MtbΔdosS mutant. Notably, a mutant of the response regulator DosR did not exhibit the attenuation in macrophages, suggesting that DosS can function independently of DosR. We identified four DosS targets in Mtb genome; Rv0440, Rv2859c, Rv0994, and Rv0260c. These genes encode functions related to hypoxia adaptation, which are not directly controlled by DosR, e.g., protein recycling and chaperoning, biosynthesis of molybdenum cofactor and nitrogen metabolism. Our results strongly suggest a DosR-independent role for DosS in Mtb.
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Affiliation(s)
- Uma S. Gautam
- Tulane National Primate Research Center, Covington, LA 70433 USA
- Present Address: Duke Human Vaccine Institute, Duke University School of Medicine, 909 S. LaSalle St., Durham, NC 27710 USA
| | - Smriti Mehra
- Tulane National Primate Research Center, Covington, LA 70433 USA
- Department of Pathobiological Sciences, Louisiana State University School of Veterinary Medicine, Baton Rouge, LA 70803 USA
- Center for Experimental Infectious Diseases Research, Louisiana State University School of Veterinary Medicine, Baton Rouge, LA 70803 USA
| | - Priyanka Kumari
- All India Institute of Medical Sciences, New Delhi, 110029 India
| | - Xavier Alvarez
- Tulane National Primate Research Center, Covington, LA 70433 USA
| | - Tianhua Niu
- Department of Biochemistry, Tulane University School of Medicine, New Orleans, 70112 LA USA
| | - Jaya S. Tyagi
- All India Institute of Medical Sciences, New Delhi, 110029 India
- Centre for Bio-design and Diagnostics, Translational Health Science and Technology Institute Faridabad, Haryana, 121001 India
| | - Deepak Kaushal
- Tulane National Primate Research Center, Covington, LA 70433 USA
- Department of Microbiology and Immunology, Tulane University School of Medicine, New Orleans, 70112 LA USA
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6
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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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7
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Sharma S, Tyagi JS. Mycobacterium tuberculosis DevR/DosR Dormancy Regulator Activation Mechanism: Dispensability of Phosphorylation, Cooperativity and Essentiality of α10 Helix. PLoS One 2016; 11:e0160723. [PMID: 27490491 PMCID: PMC4973870 DOI: 10.1371/journal.pone.0160723] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2016] [Accepted: 07/22/2016] [Indexed: 01/17/2023] Open
Abstract
DevR/DosR is a well-characterized regulator in Mycobacterium tuberculosis which is implicated in various processes ranging from dormancy/persistence to drug tolerance. DevR induces the expression of an ~48-gene dormancy regulon in response to gaseous stresses, including hypoxia. Strains of the Beijing lineage constitutively express this regulon, which may confer upon them a significant advantage, since they would be ‘pre-adapted’ to the environmental stresses that predominate during infection. Aerobic DevR regulon expression in laboratory-manipulated overexpression strains is also reported. In both instances, the need for an inducing signal is bypassed. While a phosphorylation-mediated conformational change in DevR was proposed as the activation mechanism under hypoxia, the mechanism underlying constitutive expression is not understood. Because DevR is implicated in bacterial dormancy/persistence and is a promising drug target, it is relevant to resolve the mechanistic puzzle of hypoxic activation on one hand and constitutive expression under ‘non-inducing’ conditions on the other. Here, an overexpression strategy was employed to elucidate the DevR activation mechanism. Using a panel of kinase and transcription factor mutants, we establish that DevR, upon overexpression, circumvents DevS/DosT sensor kinase-mediated or small molecule phosphodonor-dependent activation, and also cooperativity-mediated effects, which are key aspects of hypoxic activation mechanism. However, overexpression failed to rescue the defect of C-terminal-truncated DevR lacking the α10 helix, establishing the α10 helix as an indispensable component of DevR activation mechanism. We propose that aerobic overexpression of DevR likely increases the concentration of α10 helix-mediated active dimer species to above the threshold level, as during hypoxia, and enables regulon expression. This advance in the understanding of DevR activation mechanism clarifies a long standing question as to the mechanism of DevR overexpression-mediated induction of the regulon in the absence of the normal environmental cue and establishes the α10 helix as an universal and pivotal targeting interface for DevR inhibitor development.
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Affiliation(s)
- Saurabh Sharma
- Department of Biotechnology, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India
| | - Jaya Sivaswami Tyagi
- Department of Biotechnology, All India Institute of Medical Sciences, Ansari Nagar, New Delhi, India
- * E-mail: ;
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8
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Kaur K, Kumari P, Sharma S, Sehgal S, Tyagi JS. DevS/DosS sensor is bifunctional and its phosphatase activity precludes aerobic DevR/DosR regulon expression inMycobacterium tuberculosis. FEBS J 2016; 283:2949-62. [DOI: 10.1111/febs.13787] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2016] [Revised: 06/04/2016] [Accepted: 06/20/2016] [Indexed: 11/26/2022]
Affiliation(s)
- Kohinoor Kaur
- Department of Biotechnology; All India Institute of Medical Sciences; New Delhi India
| | - Priyanka Kumari
- Department of Biotechnology; All India Institute of Medical Sciences; New Delhi India
| | - Saurabh Sharma
- Department of Biotechnology; All India Institute of Medical Sciences; New Delhi India
| | - Snigdha Sehgal
- Department of Biotechnology; All India Institute of Medical Sciences; New Delhi India
| | - Jaya Sivaswami Tyagi
- Department of Biotechnology; All India Institute of Medical Sciences; New Delhi India
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9
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Rammohan J, Ruiz Manzano A, Garner AL, Prusa J, Stallings CL, Galburt EA. Cooperative stabilization of Mycobacterium tuberculosis rrnAP3 promoter open complexes by RbpA and CarD. Nucleic Acids Res 2016; 44:7304-13. [PMID: 27342278 PMCID: PMC5009747 DOI: 10.1093/nar/gkw577] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Accepted: 06/16/2016] [Indexed: 01/24/2023] Open
Abstract
The essential mycobacterial transcriptional regulators RbpA and CarD act to modulate transcription by associating to the initiation complex and increasing the flux of transcript production. Each of these factors interacts directly with the promoter DNA template and with RNA polymerase (RNAP) holoenzyme. We recently reported on the energetics of CarD-mediated open complex stabilization on the Mycobacterium tuberculosis rrnAP3 ribosomal promoter using a stopped-flow fluorescence assay. Here, we apply this approach to RbpA and show that RbpA stabilizes RNAP-promoter open complexes (RPo) via a distinct mechanism from that of CarD. Furthermore, concentration-dependent stopped-flow experiments with both factors reveal positive linkage (cooperativity) between RbpA and CarD with regard to their ability to stabilize RPo The observation of positive linkage between RbpA and CarD demonstrates that the two factors can act on the same transcription initiation complex simultaneously. Lastly, with both factors present, the kinetics of open complex formation is significantly faster than in the presence of either factor alone and approaches that of E. coli RNAP on the same promoter. This work provides a quantitative framework for the molecular mechanisms of these two essential transcription factors and the critical roles they play in the biology and pathology of mycobacteria.
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Affiliation(s)
- Jayan Rammohan
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Ana Ruiz Manzano
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Ashley L Garner
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Jerome Prusa
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Christina L Stallings
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO 63110, USA
| | - Eric A Galburt
- Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, St. Louis, MO 63110, USA
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10
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Vashist A, Prithvi Raj D, Gupta UD, Bhat R, Tyagi JS. The α10 helix of DevR, the Mycobacterium tuberculosis dormancy response regulator, regulates its DNA binding and activity. FEBS J 2016; 283:1286-99. [PMID: 26799615 DOI: 10.1111/febs.13664] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Revised: 01/05/2016] [Accepted: 01/18/2016] [Indexed: 11/26/2022]
Abstract
The crystal structures of several bacterial response regulators provide insight into the various interdomain molecular interactions potentially involved in maintaining their 'active' or 'inactive' states. However, the requirement of high concentrations of protein, an optimal pH and ionic strength buffers during crystallization may result in a structure somewhat different from that observed in solution. Therefore, functional assessment of the physiological relevance of the crystal structure data is imperative. DevR/DosR dormancy regulator of Mycobacterium tuberculosis (Mtb) belongs to the NarL subfamily of response regulators. The crystal structure of unphosphorylated DevR revealed that it forms a dimer through the α5/α6 interface. It was proposed that phosphorylation may trigger extensive structural rearrangements in DevR that culminate in the formation of a DNA-binding competent dimeric species via α10-α10 helix interactions. The α10 helix-deleted DevR protein (DevR∆α10 ) was hyperphosphorylated but defective with respect to in vitro DNA binding. Biophysical characterization reveals that DevR∆α10 has an open but less stable conformation. The combined cross-linking and DNA-binding data demonstrate that the α10 helix is essential for the formation and stabilization of the DNA-binding proficient DevR structure in both the phosphorylated and unphosphorylated states. Genetic studies establish that Mtb strains expressing DevR∆α10 are defective with respect to dormancy regulon expression under hypoxia. The present study highlights the indispensable role of the α10 helix in DevR activation and function under hypoxia and establishes the α10-α10 helix interface as a novel target for developing inhibitors against DevR, a key regulator of hypoxia-triggered dormancy.
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Affiliation(s)
- Atul Vashist
- Department of Biotechnology, All India Institute of Medical Sciences, New Delhi, India.,Experimental Animal Facility, National JALMA Institute of Leprosy and Other Mycobacterial Diseases, Tajganj, Agra, India
| | - D Prithvi Raj
- Department of Biotechnology, All India Institute of Medical Sciences, New Delhi, India
| | - Umesh Datta Gupta
- Experimental Animal Facility, National JALMA Institute of Leprosy and Other Mycobacterial Diseases, Tajganj, Agra, India
| | - Rajiv Bhat
- School of Biotechnology, Jawaharlal Nehru University, New Delhi, India
| | - Jaya Sivaswami Tyagi
- Department of Biotechnology, All India Institute of Medical Sciences, New Delhi, India
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11
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Marion E, Jarry U, Cano C, Savary C, Beauvillain C, Robbe-Saule M, Preisser L, Altare F, Delneste Y, Jeannin P, Marsollier L. FVB/N Mice Spontaneously Heal Ulcerative Lesions Induced by Mycobacterium ulcerans and Switch M. ulcerans into a Low Mycolactone Producer. THE JOURNAL OF IMMUNOLOGY 2016; 196:2690-8. [DOI: 10.4049/jimmunol.1502194] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Accepted: 01/15/2016] [Indexed: 12/29/2022]
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12
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Katsir G, Jarvis M, Phillips M, Ma Z, Gunsalus RP. The Escherichia coli NarL receiver domain regulates transcription through promoter specific functions. BMC Microbiol 2015; 15:174. [PMID: 26307095 PMCID: PMC4549865 DOI: 10.1186/s12866-015-0502-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2015] [Accepted: 08/06/2015] [Indexed: 12/20/2022] Open
Abstract
Background The Escherichia coli response regulator NarL controls transcription of genes involved in nitrate respiration during anaerobiosis. NarL consists of two domains joined by a linker that wraps around the interdomain interface. Phosphorylation of the NarL N-terminal receiver domain (RD) releases the, otherwise sequestered, C-terminal output domain (OD) that subsequently binds specific DNA promoter sites to repress or activate gene expression. The aim of this study is to investigate the extent to which the NarL OD and RD function independently to regulate transcription, and the affect of the linker on OD function. Results NarL OD constructs containing different linker segments were examined for their ability to repress frdA-lacZ or activate narG-lacZ reporter fusion genes. These in vivo expression assays revealed that the NarL OD, in the absence or presence of linker helix α6, constitutively repressed frdA-lacZ expression regardless of nitrate availability. However, the presence of the linker loop α5-α6 reversed this repression and also showed impaired DNA binding in vitro. The OD alone could not activate narG-lacZ expression; this activity required the presence of the NarL RD. A footprint assay demonstrated that the NarL OD only partially bound recognition sites at the narG promoter, and the binding affinity was increased by the presence of the phosphorylated RD. Analytical ultracentrifugation used to examine domain oligomerization showed that the NarL RD forms dimers in solution while the OD is monomeric. Conclusions The NarL RD operates as an on-off switch to occlude or release the OD in a nitrate-responsive manner, but has additional roles to directly stimulate transcription at promoters for which the OD lacks independent function. One such role of the RD is to enhance the DNA binding affinity of the OD to target promoter sites. The data also imply that NarL phosphorylation results in RD dimerization and in the separation of the entire linker region from the OD. Electronic supplementary material The online version of this article (doi:10.1186/s12866-015-0502-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Galit Katsir
- Department of Chemistry and Biochemistry, University of California, Los Angeles, USA.,Molecular Biology Institute, University of California, Los Angeles, USA.,Present address: San Jose City College, San Jose, CA, USA
| | - Michael Jarvis
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, USA.,Present address: Ambry Genetics, Aliso Viejo, CA, USA
| | - Martin Phillips
- Department of Chemistry and Biochemistry, University of California, Los Angeles, USA
| | - Zhongcai Ma
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, USA.,Present address: NeuroInDx, Inc, Signal Hill, CA, USA
| | - Robert P Gunsalus
- Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, USA. .,Molecular Biology Institute, University of California, Los Angeles, USA.
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13
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Gautam US, Mehra S, Kaushal D. In-Vivo Gene Signatures of Mycobacterium tuberculosis in C3HeB/FeJ Mice. PLoS One 2015; 10:e0135208. [PMID: 26270051 PMCID: PMC4535907 DOI: 10.1371/journal.pone.0135208] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Accepted: 07/19/2015] [Indexed: 11/28/2022] Open
Abstract
Despite considerable progress in understanding the pathogenesis of Mycobacterium tuberculosis (Mtb), development of new therapeutics and vaccines against it has proven difficult. This is at least in part due to the use of less than optimal models of in-vivo Mtb infection, which has precluded a study of the physiology of the pathogen in niches where it actually persists. C3HeB/FeJ (Kramnik) mice develop human-like lesions when experimentally infected with Mtb and thus make available, a faithful and highly tractable system to study the physiology of the pathogen in-vivo. We compared the transcriptomics of Mtb and various mutants in the DosR (DevR) regulon derived from Kramnik mouse granulomas to those cultured in-vitro. We recently showed that mutant ΔdosS is attenuated in C3HeB/FeJ mice. Aerosol exposure of mice with the mutant mycobacteria resulted in a substantially different and a relatively weaker transcriptional response (< = 20 genes were induced) for the functional category ‘Information Pathways’ in Mtb:ΔdosR; ‘Lipid Metabolism’ in Mtb:ΔdosT; ‘Virulence, Detoxification, Adaptation’ in both Mtb:ΔdosR and Mtb:ΔdosT; and ‘PE/PPE’ family in all mutant strains compare to wild-type Mtb H37Rv, suggesting that the inability to induce DosR functions to different levels can modulate the interaction of the pathogen with the host. The Mtb genes expressed during growth in C3HeB/FeJ mice appear to reflect adaptation to differential nutrient utilization for survival in mouse lungs. The genes such as glnB, Rv0744c, Rv3281, sdhD/B, mce4A, dctA etc. downregulated in mutant ΔdosS indicate their requirement for bacterial growth and flow of carbon/energy source from host cells. We conclude that genes expressed in Mtb during in-vivo chronic phase of infection in Kramnik mice mainly contribute to growth, cell wall processes, lipid metabolism, and virulence.
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Affiliation(s)
- Uma Shankar Gautam
- Tulane National Primate Research Center, Covington, Louisiana, United States of America
- * E-mail: (DK); (USG)
| | - Smriti Mehra
- Tulane National Primate Research Center, Covington, Louisiana, United States of America
- Louisiana State University School of Veterinary Medicine Department of Pathobiological Sciences, Baton Rouge, Louisiana, United States of America
| | - Deepak Kaushal
- Tulane National Primate Research Center, Covington, Louisiana, United States of America
- Microbiology and Immunology, Tulane University School of Medicine, New Orleans, Louisiana, United States of America
- * E-mail: (DK); (USG)
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Malhotra V, Agrawal R, Duncan TR, Saini DK, Clark-Curtiss JE. Mycobacterium tuberculosis response regulators, DevR and NarL, interact in vivo and co-regulate gene expression during aerobic nitrate metabolism. J Biol Chem 2015; 290:8294-309. [PMID: 25659431 DOI: 10.1074/jbc.m114.591800] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mycobacterium tuberculosis genes Rv0844c/Rv0845 encoding the NarL response regulator and NarS histidine kinase are hypothesized to constitute a two-component system involved in the regulation of nitrate metabolism. However, there is no experimental evidence to support this. In this study, we established M. tuberculosis NarL/NarS as a functional two-component system and identified His(241) and Asp(61) as conserved phosphorylation sites in NarS and NarL, respectively. Transcriptional profiling between M. tuberculosis H37Rv and a ΔnarL mutant strain during exponential growth in broth cultures with or without nitrate defined an ∼30-gene NarL regulon that exhibited significant overlap with DevR-regulated genes, thereby implicating a role for the DevR response regulator in the regulation of nitrate metabolism. Notably, expression analysis of a subset of genes common to NarL and DevR regulons in M. tuberculosis ΔdevR, ΔdevSΔdosT, and ΔnarL mutant strains revealed that in response to nitrite produced during aerobic nitrate metabolism, the DevRS/DosT regulatory system plays a primary role that is augmented by NarL. Specifically, NarL itself was unable to bind to the narK2, acg, and Rv3130c promoters in phosphorylated or unphosphorylated form; however, its interaction with DevR∼P resulted in cooperative binding, thereby enabling co-regulation of these genes. These findings support the role of physiologically derived nitrite as a metabolic signal in mycobacteria. We propose NarL-DevR binding, possibly as a heterodimer, as a novel mechanism for co-regulation of gene expression by the DevRS/DosT and NarL/NarS regulatory systems.
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Affiliation(s)
- Vandana Malhotra
- From the Center for Infectious Diseases and Vaccinology, Biodesign Institute, and
| | - Ruchi Agrawal
- the Department of Molecular Reproduction, Development, and Genetics, Indian Institute of Science, Bangalore 560012, India
| | - Tammi R Duncan
- From the Center for Infectious Diseases and Vaccinology, Biodesign Institute, and the School of Life Sciences, Arizona State University, Tempe, Arizona 85287 and
| | - Deepak K Saini
- the Department of Molecular Reproduction, Development, and Genetics, Indian Institute of Science, Bangalore 560012, India
| | - Josephine E Clark-Curtiss
- From the Center for Infectious Diseases and Vaccinology, Biodesign Institute, and the School of Life Sciences, Arizona State University, Tempe, Arizona 85287 and
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DevR (DosR) mimetic peptides impair transcriptional regulation and survival of Mycobacterium tuberculosis under hypoxia by inhibiting the autokinase activity of DevS sensor kinase. BMC Microbiol 2014; 14:195. [PMID: 25048654 PMCID: PMC4110071 DOI: 10.1186/1471-2180-14-195] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2014] [Accepted: 07/11/2014] [Indexed: 01/06/2023] Open
Abstract
Background Two-component systems have emerged as compelling targets for antibacterial drug design for a number of reasons including the distinct histidine phosphorylation property of their constituent sensor kinases. The DevR-DevS/DosT two component system of Mycobacterium tuberculosis (M. tb) is essential for survival under hypoxia, a stress associated with dormancy development in vivo. In the present study a combinatorial peptide phage display library was screened for DevS histidine kinase interacting peptides with the aim of isolating inhibitors of DevR-DevS signaling. Results DevS binding peptides were identified from a phage display library after three rounds of panning using DevS as bait. The peptides showed sequence similarity with conserved residues in the N-terminal domain of DevR and suggested that they may represent interacting surfaces between DevS and DevR. Two DevR mimetic peptides were found to specifically inhibit DevR-dependent transcriptional activity and restrict the hypoxic survival of M. tb. The mechanism of peptide action is majorly attributed to an inhibition of DevS autokinase activity. Conclusions These findings demonstrate that DevR mimetic peptides impede DevS activation and that intercepting DevS activation at an early step in the signaling cascade impairs M. tb survival in a hypoxia persistence model.
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Essentiality of DevR/DosR interaction with SigA for the dormancy survival program in Mycobacterium tuberculosis. J Bacteriol 2013; 196:790-9. [PMID: 24317401 DOI: 10.1128/jb.01270-13] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The DevR/DosR regulator is believed to play a key role in dormancy adaptation mechanisms of Mycobacterium tuberculosis in response to a multitude of gaseous stresses, including hypoxia, which prevails within granulomas. DevR activates transcription by binding to target promoters containing a minimum of two binding sites. The proximal site overlaps with the SigA -35 element, suggesting that DevR-SigA interaction is required for activating transcription. We evaluated the roles of 14 charged residues of DevR in transcriptional activation under hypoxic stress. Seven of the 14 alanine substitution mutants were defective in regulon activation, of which K191A, R197A, and K179A+K168A (designated K179A*) mutants were significantly or completely compromised in DNA binding. Four mutants, namely, E154A, R155A, E178A, and K208A, were activation defective in spite of binding to DNA and were classified as positive-control (pc) mutants. The SigA interaction defect of the E154A and E178A proteins was established by in vitro and in vivo assays and implies that these substitutions lead to an activation defect because they disrupt an interaction(s) with SigA. The relevance of DevR interaction to the transcriptional machinery was further established by the hypoxia survival phenotype displayed by SigA interaction-defective mutants. Our findings demonstrate the role of DevR-SigA interaction in the activation mechanism and in bacterial survival under hypoxia and establish the housekeeping sigma factor SigA as a molecular target of DevR. The interaction of DevR and RNA polymerase suggests a new and novel interceptable molecular interface for future antidormancy strategies for Mycobacterium tuberculosis.
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Zoltowski BD, Motta-Mena LB, Gardner KH. Blue light-induced dimerization of a bacterial LOV-HTH DNA-binding protein. Biochemistry 2013; 52:6653-61. [PMID: 23992349 DOI: 10.1021/bi401040m] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
With their utilization of light-driven allostery to control biochemical activities, photosensory proteins are of great interest as model systems and novel reagents for use by the basic science and engineering communities. One such protein, the light-activated EL222 transcription factor, from the marine bacterium Erythrobacter litoralis HTCC2594, is appealing for such studies, as it harnesses blue light to drive the reorientation of light-oxygen-voltage (LOV) sensory and helix-turn-helix (HTH) effector domains to allow photoactivation of gene transcription in natural and artificial systems. The protein conformational changes required for this process are not well understood, in part because of the relatively short lifetime of the EL222 photoexcited state (τ ∼ 29 s), which complicates its characterization via certain biophysical methods. Here we report how we have circumvented this limitation by creating an EL222 variant harboring V41I, L52I, A79Q, and V121I point mutations (AQTrip) that stabilizes the photoactivated state. Using the wild-type and AQTrip EL222 proteins, we have probed EL222 activation using a combination of solution scattering, nuclear magnetic resonance (NMR), and electromobility shift assays. Size-exclusion chromatography and light scattering indicate that AQTrip oligomerizes in the absence of DNA and selects for an EL222 dimer-DNA complex in the presence of DNA substrates. These results are confirmed in wild-type EL222 with a high-affinity DNA-binding site that stabilizes the complex. NMR analyses of the EL222-DNA complex confirm a 2:1 stoichiometry in the presence of a previously characterized DNA substrate. Combined, these novel approaches have validated a key mechanistic step, whereby blue light induces EL222 dimerization through LOV and HTH interfaces.
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Affiliation(s)
- Brian D Zoltowski
- Departments of Biophysics and Biochemistry, University of Texas Southwestern Medical Center , Dallas, Texas 75390-8816, United States
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The Mycobacterium tuberculosis regulatory network and hypoxia. Nature 2013; 499:178-83. [PMID: 23823726 DOI: 10.1038/nature12337] [Citation(s) in RCA: 327] [Impact Index Per Article: 29.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2011] [Accepted: 05/23/2013] [Indexed: 12/26/2022]
Abstract
We have taken the first steps towards a complete reconstruction of the Mycobacterium tuberculosis regulatory network based on ChIP-Seq and combined this reconstruction with system-wide profiling of messenger RNAs, proteins, metabolites and lipids during hypoxia and re-aeration. Adaptations to hypoxia are thought to have a prominent role in M. tuberculosis pathogenesis. Using ChIP-Seq combined with expression data from the induction of the same factors, we have reconstructed a draft regulatory network based on 50 transcription factors. This network model revealed a direct interconnection between the hypoxic response, lipid catabolism, lipid anabolism and the production of cell wall lipids. As a validation of this model, in response to oxygen availability we observe substantial alterations in lipid content and changes in gene expression and metabolites in corresponding metabolic pathways. The regulatory network reveals transcription factors underlying these changes, allows us to computationally predict expression changes, and indicates that Rv0081 is a regulatory hub.
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A two-component system (XydS/R) controls the expression of genes encoding CBM6-containing proteins in response to straw in Clostridium cellulolyticum. PLoS One 2013; 8:e56063. [PMID: 23418511 PMCID: PMC3572039 DOI: 10.1371/journal.pone.0056063] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2012] [Accepted: 01/03/2013] [Indexed: 12/17/2022] Open
Abstract
The composition of the cellulosomes (multi enzymatic complexes involved in the degradation of plant cell wall polysaccharides) produced by Clostridium cellulolyticum differs according to the growth substrate. In particular, the expression of a cluster of 14 hemicellulase-encoding genes (called xyl-doc) seems to be induced by the presence of straw and not of cellulose. Genes encoding a putative two-component regulation system (XydS/R) were found upstream of xyl-doc. First evidence for the involvement of the response regulator, XydR, part of this two-component system, in the expression of xyl-doc genes was given by the analysis of the cellulosomes produced by a regulator overproducing strain when grown on cellulose. Nano-LC MS/MS analysis allowed the detection of the products of all xyl-doc genes and of the product of the gene at locus Ccel_1656 predicted to bear a carbohydrate binding domain targeting hemicellulose. RT-PCR experiments further demonstrated that the regulation occurs at the transcriptional level and that all xyl-doc genes are transcriptionally linked. mRNA quantification in a regulator knock-out strain and in its complemented derivative confirmed the involvement of the regulator in the expression of xyl-doc genes and of the gene at locus Ccel_1656 in response to straw. Electrophoretic mobility shift assays using the purified regulator further demonstrated that the regulator binds to DNA regions located upstream of the first gene of the xyl-doc gene cluster and upstream of the gene at locus Ccel_1656.
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Sivaramakrishnan S, de Montellano PRO. The DosS-DosT/DosR Mycobacterial Sensor System. BIOSENSORS 2013; 3:259-282. [PMID: 25002970 PMCID: PMC4082495 DOI: 10.3390/bios3030259] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Revised: 06/15/2013] [Accepted: 06/26/2013] [Indexed: 11/16/2022]
Abstract
DosS/DosR is a two-component regulatory system in which DosS, a heme-containing sensor also known as DevS, under certain conditions undergoes autophosphorylation and then transfers the phosphate to DosR, a DNA-binding protein that controls the entry of Mycobacterium tuberculosis and other mycobacteria into a latent, dormant state. DosT, a second sensor closely related to DosS, is present in M. tuberculosis and participates in the control of the dormancy response mediated by DosR. The binding of phosphorylated DosR to DNA initiates the expression of approximately fifty dormancy-linked genes. DosT is accepted to be a gas sensor that is activated in the ferrous state by the absence of an oxygen ligand or by the binding of NO or CO. DosS functions in a similar fashion as a gas sensor, but contradictory evidence has led to the suggestion that it also functions as a redox state sensor. This review focuses on the structure, biophysical properties, and function of the DosS/DosT heme sensors.
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Affiliation(s)
- Santhosh Sivaramakrishnan
- Department of Pharmaceutical Chemistry, School of Pharmacy, University of California, San Francisco, CA 94158, USA;
| | - Paul R Ortiz de Montellano
- Department of Pharmaceutical Chemistry, School of Pharmacy, University of California, San Francisco, CA 94158, USA;
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Bretl DJ, Demetriadou C, Zahrt TC. Adaptation to environmental stimuli within the host: two-component signal transduction systems of Mycobacterium tuberculosis. Microbiol Mol Biol Rev 2011; 75:566-82. [PMID: 22126994 PMCID: PMC3232741 DOI: 10.1128/mmbr.05004-11] [Citation(s) in RCA: 97] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pathogenic microorganisms encounter a variety of environmental stresses following infection of their respective hosts. Mycobacterium tuberculosis, the etiological agent of tuberculosis, is an unusual bacterial pathogen in that it is able to establish lifelong infections in individuals within granulomatous lesions that are formed following a productive immune response. Adaptation to this highly dynamic environment is thought to be mediated primarily through transcriptional reprogramming initiated in response to recognition of stimuli, including low-oxygen tension, nutrient depletion, reactive oxygen and nitrogen species, altered pH, toxic lipid moieties, cell wall/cell membrane-perturbing agents, and other environmental cues. To survive continued exposure to these potentially adverse factors, M. tuberculosis encodes a variety of regulatory factors, including 11 complete two-component signal transduction systems (TCSSs) and several orphaned response regulators (RRs) and sensor kinases (SKs). This report reviews our current knowledge of the TCSSs present in M. tuberculosis. In particular, we discuss the biochemical and functional characteristics of individual RRs and SKs, the environmental stimuli regulating their activation, the regulons controlled by the various TCSSs, and the known or postulated role(s) of individual TCSSs in the context of M. tuberculosis physiology and/or pathogenesis.
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Affiliation(s)
| | | | - Thomas C. Zahrt
- Center for Infectious Disease Research and Department of Microbiology and Molecular Genetics, Medical College of Wisconsin, 8701 Watertown Plank Road, Milwaukee, Wisconsin 53226-0509
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The residue threonine 82 of DevR (DosR) is essential for DevR activation and function in Mycobacterium tuberculosis despite its atypical location. J Bacteriol 2011; 193:4849-58. [PMID: 21764934 DOI: 10.1128/jb.05051-11] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The DevR (DosR) response regulator initiates the bacterial adaptive response to a variety of signals, including hypoxia in in vitro models of dormancy. Its receiver domain works as a phosphorylation-mediated switch to activate the DNA binding property of its output domain. Receiver domains are characterized by the presence of several highly conserved residues, and these sequence features correlate with structure and hence function. In response regulators, interaction of phosphorylated aspartic acid at the active site with the conserved threonine is believed to be crucial for phosphorylation-mediated conformational change. DevR contains all the conserved residues, but the structure of its receiver domain in the unphosphorylated protein is strikingly different, and key threonine (T82), tyrosine (Y101), and lysine (K104) residues are placed uncharacteristically far from the D54 phosphorylation site. In view of the atypical location of T82 in DevR, the present study aimed to examine the importance of this residue in the activation mechanism. Mycobacterium tuberculosis expressing a DevR T82A mutant protein is defective in autoregulation and supports hypoxic induction of the DevR regulon only very weakly. These defects are ascribed to slow and partial phosphorylation and the failure of T82A mutant protein to bind cooperatively with DNA. Our results indicate that the T82 residue is crucial in implementing conformational changes in DevR that are essential for cooperative binding and for subsequent gene activation. We propose that the function of the T82 residue in the activation mechanism of DevR is conserved in spite of the unusual architecture of its receiver domain.
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Chauhan S, Sharma D, Singh A, Surolia A, Tyagi JS. Comprehensive insights into Mycobacterium tuberculosis DevR (DosR) regulon activation switch. Nucleic Acids Res 2011; 39:7400-14. [PMID: 21653552 PMCID: PMC3177182 DOI: 10.1093/nar/gkr375] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
DevR regulon function is believed to be crucial for the survival of Mycobacterium tuberculosis during dormancy. In this study, we undertook a comprehensive analysis of the DevR regulon. All the regulon promoters were assigned to four classes based on the number of DevR binding sites (Dev boxes). A minimum of two boxes are essential for complete interaction and their tandem arrangement is an architectural hallmark at all promoters. Initial interaction of DevR with the conserved box is essential for its cooperative binding to adjacent sites bearing low to very poor sequence conservation and is the universal mechanism underlying DevR-mediated transcriptional induction. The functional importance of tandem arrangement was established by analyzing promoter variants harboring Dev boxes with altered spacing. Conserved sequence logos were generated from 47 binding sequences which included 24 newly discovered Dev boxes. In each half site of an 18-bp binding motif, G5 and C7 are essential for DevR binding. Finally, we show that DevR regulon induction occurs in a temporal manner and genes that are induced early are also usually powerfully induced. The information theory-based approach along with binding and temporal expression studies provide us with comprehensive insights into the complex pattern of DevR regulon activation.
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Affiliation(s)
- Santosh Chauhan
- Department of Biotechnology, All India Institute of Medical Sciences, Ansari Nagar, New Delhi 110029, India
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