51
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Anil Kumar V, Goyal R, Bansal R, Singh N, Sevalkar RR, Kumar A, Sarkar D. EspR-dependent ESAT-6 Protein Secretion of Mycobacterium tuberculosis Requires the Presence of Virulence Regulator PhoP. J Biol Chem 2016; 291:19018-30. [PMID: 27445330 DOI: 10.1074/jbc.m116.746289] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2016] [Indexed: 01/09/2023] Open
Abstract
Attenuation of Mycobacterium bovis BCG strain is related to the loss of the RD1-encoded ESX-1 secretion system. The ESX-1 system secretes virulence factor ESAT-6 that plays a critical role in modulation of the host immune system, which is essential for establishment of a productive infection. Previous studies suggest that among the reasons for attenuation of Mycobacterium tuberculosis H37Ra is a mutation in the phoP gene that interferes with the ESX-1 secretion system and inhibits secretion of ESAT-6. Here, we identify a totally different and distinct regulatory mechanism involving PhoP and transcription regulator EspR on transcriptional control of the espACD operon, which is required for ESX-1-dependent ESAT-6 secretion. Although both of these regulators are capable of influencing espACD expression, we show that activation of espACD requires direct recruitment of both PhoP and EspR at the espACD promoter. The most fundamental insights are derived from the inhibition of EspR binding at the espACD regulatory region of the phoP mutant strain because of PhoP-EspR protein-protein interactions. Based on these results, a model is proposed suggesting how PhoP and EspR protein-protein interactions contribute to activation of espACD expression and, in turn, control ESAT-6 secretion, an essential pathogenic determinant of M. tuberculosis Together, these results have significant implications on the mechanism of virulence regulation of M. tuberculosis.
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Affiliation(s)
- Vijjamarri Anil Kumar
- From the Council of Scientific and Industrial Research-Institute of Microbial Technology, Sector 39 A, Chandigarh 160036, India
| | - Rajni Goyal
- From the Council of Scientific and Industrial Research-Institute of Microbial Technology, Sector 39 A, Chandigarh 160036, India
| | - Roohi Bansal
- From the Council of Scientific and Industrial Research-Institute of Microbial Technology, Sector 39 A, Chandigarh 160036, India
| | - Nisha Singh
- From the Council of Scientific and Industrial Research-Institute of Microbial Technology, Sector 39 A, Chandigarh 160036, India
| | - Ritesh Rajesh Sevalkar
- From the Council of Scientific and Industrial Research-Institute of Microbial Technology, Sector 39 A, Chandigarh 160036, India
| | - Ashwani Kumar
- From the Council of Scientific and Industrial Research-Institute of Microbial Technology, Sector 39 A, Chandigarh 160036, India
| | - Dibyendu Sarkar
- From the Council of Scientific and Industrial Research-Institute of Microbial Technology, Sector 39 A, Chandigarh 160036, India
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52
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Chinta KC, Saini V, Glasgow JN, Mazorodze JH, Rahman MA, Reddy D, Lancaster JR, Steyn AJC. The emerging role of gasotransmitters in the pathogenesis of tuberculosis. Nitric Oxide 2016; 59:28-41. [PMID: 27387335 DOI: 10.1016/j.niox.2016.06.009] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Accepted: 06/30/2016] [Indexed: 12/17/2022]
Abstract
Mycobacterium tuberculosis (Mtb) is a facultative intracellular pathogen and the second largest contributor to global mortality caused by an infectious agent after HIV. In infected host cells, Mtb is faced with a harsh intracellular environment including hypoxia and the release of nitric oxide (NO) and carbon monoxide (CO) by immune cells. Hypoxia, NO and CO induce a state of in vitro dormancy where Mtb senses these gases via the DosS and DosT heme sensor kinase proteins, which in turn induce a set of ∼47 genes, known as the Mtb Dos dormancy regulon. On the contrary, both iNOS and HO-1, which produce NO and CO, respectively, have been shown to be important against mycobacterial disease progression. In this review, we discuss the impact of O2, NO and CO on Mtb physiology and in host responses to Mtb infection as well as the potential role of another major endogenous gas, hydrogen sulfide (H2S), in Mtb pathogenesis.
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Affiliation(s)
- Krishna C Chinta
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Vikram Saini
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL, USA; UAB Center for Free Radical Biology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - Joel N Glasgow
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL, USA
| | - James H Mazorodze
- KwaZulu-Natal Research Institute for TB and HIV (KRITH), Durban, South Africa
| | - Md Aejazur Rahman
- KwaZulu-Natal Research Institute for TB and HIV (KRITH), Durban, South Africa
| | - Darshan Reddy
- Department of Cardiothoracic Surgery, Nelson R Mandela School of Medicine, University of KwaZulu Natal, Durban, South Africa
| | - Jack R Lancaster
- Department of Pharmacology and Chemical Biology, University of Pittsburgh, Pittsburgh, PA, USA
| | - Adrie J C Steyn
- Department of Microbiology, University of Alabama at Birmingham, Birmingham, AL, USA; KwaZulu-Natal Research Institute for TB and HIV (KRITH), Durban, South Africa; UAB Center for Free Radical Biology, University of Alabama at Birmingham, Birmingham, AL, USA.
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53
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O'Connor G, Gleeson LE, Fagan-Murphy A, Cryan SA, O'Sullivan MP, Keane J. Sharpening nature's tools for efficient tuberculosis control: A review of the potential role and development of host-directed therapies and strategies for targeted respiratory delivery. Adv Drug Deliv Rev 2016; 102:33-54. [PMID: 27151307 DOI: 10.1016/j.addr.2016.04.024] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2016] [Revised: 04/04/2016] [Accepted: 04/20/2016] [Indexed: 12/18/2022]
Abstract
Centuries since it was first described, tuberculosis (TB) remains a significant global public health issue. Despite ongoing holistic measures implemented by health authorities and a number of new oral treatments reaching the market, there is still a need for an advanced, efficient TB treatment. An adjunctive, host-directed therapy designed to enhance endogenous pathways and hence compliment current regimens could be the answer. The integration of drug repurposing, including synthetic and naturally occurring compounds, with a targeted drug delivery platform is an attractive development option. In order for a new anti-tubercular treatment to be produced in a timely manner, a multidisciplinary approach should be taken from the outset including stakeholders from academia, the pharmaceutical industry, and regulatory bodies keeping the patient as the key focus. Pre-clinical considerations for the development of a targeted host-directed therapy are discussed here.
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Affiliation(s)
- Gemma O'Connor
- School of Pharmacy, Royal College of Surgeons in Ireland, Dublin 2, Ireland; Department of Clinical Medicine, Institute of Molecular Medicine, Trinity College Dublin and St. James's Hospital, D08 W9RT, Dublin, Ireland.
| | - Laura E Gleeson
- Department of Clinical Medicine, Institute of Molecular Medicine, Trinity College Dublin and St. James's Hospital, D08 W9RT, Dublin, Ireland.
| | - Aidan Fagan-Murphy
- School of Pharmacy, Royal College of Surgeons in Ireland, Dublin 2, Ireland; SFI Centre for Research in Medical Devices (CURAM), Dublin 2, Ireland.
| | - Sally-Ann Cryan
- School of Pharmacy, Royal College of Surgeons in Ireland, Dublin 2, Ireland; Trinity Centre for Bioengineering, Trinity College Dublin, Dublin 2, Ireland; SFI Centre for Research in Medical Devices (CURAM), Dublin 2, Ireland.
| | - Mary P O'Sullivan
- Department of Clinical Medicine, Institute of Molecular Medicine, Trinity College Dublin and St. James's Hospital, D08 W9RT, Dublin, Ireland.
| | - Joseph Keane
- Department of Clinical Medicine, Institute of Molecular Medicine, Trinity College Dublin and St. James's Hospital, D08 W9RT, Dublin, Ireland.
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54
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Banerjee SK, Kumar M, Alokam R, Sharma AK, Chatterjee A, Kumar R, Sahu SK, Jana K, Singh R, Yogeeswari P, Sriram D, Basu J, Kundu M. Targeting multiple response regulators of Mycobacterium tuberculosis augments the host immune response to infection. Sci Rep 2016; 6:25851. [PMID: 27181265 PMCID: PMC4867592 DOI: 10.1038/srep25851] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Accepted: 04/25/2016] [Indexed: 11/06/2022] Open
Abstract
The genome of M. tuberculosis (Mtb) encodes eleven paired two component systems (TCSs) consisting of a sensor kinase (SK) and a response regulator (RR). The SKs sense environmental signals triggering RR-dependent gene expression pathways that enable the bacterium to adapt in the host milieu. We demonstrate that a conserved motif present in the C-terminal domain regulates the DNA binding functions of the OmpR family of Mtb RRs. Molecular docking studies against this motif helped to identify two molecules with a thiazolidine scaffold capable of targeting multiple RRs, and modulating their regulons to attenuate bacterial replication in macrophages. The changes in the bacterial transcriptome extended to an altered immune response with increased autophagy and NO production, leading to compromised survival of Mtb in macrophages. Our findings underscore the promise of targeting multiple RRs as a novel yet unexplored approach for development of new anti-mycobacterial agents particularly against drug-resistant Mtb.
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Affiliation(s)
- Srijon Kaushik Banerjee
- Department of Chemistry, Bose Institute, 93/1 Acharya Prafulla Chandra Road, Kolkata 700009, India
| | - Manish Kumar
- Department of Chemistry, Bose Institute, 93/1 Acharya Prafulla Chandra Road, Kolkata 700009, India
| | - Reshma Alokam
- Department of Pharmacy, Birla Institute of Technology &Science-Pilani, Hyderabad Campus, Jawahar Nagar, Hyderabad 500078, India
| | - Arun Kumar Sharma
- Department of Chemistry, Bose Institute, 93/1 Acharya Prafulla Chandra Road, Kolkata 700009, India
| | - Ayan Chatterjee
- Department of Chemistry, Bose Institute, 93/1 Acharya Prafulla Chandra Road, Kolkata 700009, India
| | - Ranjeet Kumar
- Department of Chemistry, Bose Institute, 93/1 Acharya Prafulla Chandra Road, Kolkata 700009, India
| | - Sanjaya Kumar Sahu
- Department of Chemistry, Bose Institute, 93/1 Acharya Prafulla Chandra Road, Kolkata 700009, India
| | - Kuladip Jana
- Division of Molecular Medicine, Bose Institute, P-1/12 CIT Scheme VII M, Kolkata 700054, India
| | - Ramandeep Singh
- Vaccine and Infectious Disease Research Centre, Translational Health Science and Technology Institute, NCR-Biotech Science Cluster, 3rd Milestone, Faridabad Gurgaon Expressway. Faridabad-121001, India
| | - Perumal Yogeeswari
- Department of Pharmacy, Birla Institute of Technology &Science-Pilani, Hyderabad Campus, Jawahar Nagar, Hyderabad 500078, India
| | - Dharmarajan Sriram
- Department of Pharmacy, Birla Institute of Technology &Science-Pilani, Hyderabad Campus, Jawahar Nagar, Hyderabad 500078, India
| | - Joyoti Basu
- Department of Chemistry, Bose Institute, 93/1 Acharya Prafulla Chandra Road, Kolkata 700009, India
| | - Manikuntala Kundu
- Department of Chemistry, Bose Institute, 93/1 Acharya Prafulla Chandra Road, Kolkata 700009, India
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55
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Abstract
Adult or postprimary tuberculosis (TB) accounts for most TB cases. Its hallmark is pulmonary cavitation, which occurs as a result of necrosis in the lung in individuals with tuberculous pneumonia. Postprimary TB has previously been known to be associated with vascular thrombosis and delayed-type hypersensitivity, but their roles in pulmonary cavitation are unclear. A necrosis-associated extracellular cluster (NEC) refers to a cluster of drug-tolerant Mycobacterium tuberculosis attached to lysed host materials and is proposed to contribute to granulomatous TB. Here we suggest that NECs, perhaps due to big size, produce a distinct host response leading to postprimary TB. We propose that vascular thrombosis and pneumonia arise from NEC and that these processes are promoted by inflammatory cytokines produced from cell-mediated delayed-type hypersensitivity, such as interleukin-17 and gamma interferon, eventually triggering necrosis in the lung and causing cavitation. According to this view, targeting NEC represents a necessary strategy to control adult TB.
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56
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Mertaniasih NM, Handijatno D, Perwitasari ADS, Dewi DNSS, Fanani MZ, Afifah IQ. Sequence Analysis of the Gene Region Encoding ESAT-6, Ag85B, and Ag85C Proteins from Clinical Isolates of Mycobacterium tuberculosis. ACTA ACUST UNITED AC 2016. [DOI: 10.1016/j.proche.2016.01.035] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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57
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Jose L, Ramachandran R, Bhagavat R, Gomez RL, Chandran A, Raghunandanan S, Omkumar RV, Chandra N, Mundayoor S, Kumar RA. Hypothetical protein Rv3423.1 ofMycobacterium tuberculosisis a histone acetyltransferase. FEBS J 2015; 283:265-81. [DOI: 10.1111/febs.13566] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2015] [Revised: 09/28/2015] [Accepted: 10/15/2015] [Indexed: 12/15/2022]
Affiliation(s)
- Leny Jose
- Mycobacterium Research Group; Tropical Disease Biology Division; Rajiv Gandhi Centre for Biotechnology; Thiruvananthapuram India
| | - Ranjit Ramachandran
- Mycobacterium Research Group; Tropical Disease Biology Division; Rajiv Gandhi Centre for Biotechnology; Thiruvananthapuram India
| | - Raghu Bhagavat
- Bioinformatics Centre; Indian Institute of Science; Bangalore India
| | - Roshna Lawrence Gomez
- Mycobacterium Research Group; Tropical Disease Biology Division; Rajiv Gandhi Centre for Biotechnology; Thiruvananthapuram India
| | - Aneesh Chandran
- Mycobacterium Research Group; Tropical Disease Biology Division; Rajiv Gandhi Centre for Biotechnology; Thiruvananthapuram India
| | - Sajith Raghunandanan
- Mycobacterium Research Group; Tropical Disease Biology Division; Rajiv Gandhi Centre for Biotechnology; Thiruvananthapuram India
| | | | - Nagasuma Chandra
- Bioinformatics Centre; Indian Institute of Science; Bangalore India
| | - Sathish Mundayoor
- Mycobacterium Research Group; Tropical Disease Biology Division; Rajiv Gandhi Centre for Biotechnology; Thiruvananthapuram India
| | - Ramakrishnan Ajay Kumar
- Mycobacterium Research Group; Tropical Disease Biology Division; Rajiv Gandhi Centre for Biotechnology; Thiruvananthapuram India
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58
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Majlessi L, Prados-Rosales R, Casadevall A, Brosch R. Release of mycobacterial antigens. Immunol Rev 2015; 264:25-45. [PMID: 25703550 DOI: 10.1111/imr.12251] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Mycobacterium tuberculosis has evolved from a Mycobacterium canettii-like progenitor pool into one of the most successful and widespread human pathogens. The pathogenicity of M. tuberculosis is linked to its ability to secrete/export/release selected mycobacterial proteins, and it is also established that active release of mycobacterial antigens is a prerequisite for strong immune recognition. Recent research has enabled mycobacterial secretion systems and vesicle-based release of mycobacterial antigens to be elucidated, which together with host-related specificities constitute key variables that determine the outcome of infection. Here, we discuss recently discovered, novel aspects on the nature and the regulation of antigen release of the tuberculosis agent with particular emphasis on the biological characterization of mycobacteria-specific ESX/type VII secretion systems and their secreted proteins, belonging to the Esx, PE, and PPE categories. The importance of specific mycobacterial antigen release is probably best exemplified by the striking differences observed between the cellular events during infection with the ESX-1-deficient, attenuated Mycobacterium bovis BCG compared to the virulent M. tuberculosis, which are clearly important for design of more specific diagnostics and more efficient vaccines.
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Affiliation(s)
- Laleh Majlessi
- Institut Pasteur, Unit for Integrated Mycobacterial Pathogenomics, Paris, France
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59
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Evolutionary landscape of the Mycobacterium tuberculosis complex from the viewpoint of PhoPR: implications for virulence regulation and application to vaccine development. mBio 2015; 6:e01289-15. [PMID: 26489860 PMCID: PMC4620462 DOI: 10.1128/mbio.01289-15] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
Different members of the Mycobacterium genus have evolved to cause tuberculosis in diverse human populations and in a variety of animal species. Our cumulative knowledge of mycobacterial genomes indicates that mutations in the PhoPR two-component virulence system were acquired not only during the natural evolution of mycobacterial species but also during in vitro subculture, which has given rise to the attenuated reference strain H37Ra or to different daughter strains of Mycobacterium bovis BCG. PhoPR is a well-known regulator of pathogenic phenotypes, including secretion of the virulence factor ESAT-6, biosynthesis of acyltrehalose-based lipids, and modulation of antigen export, in members of the Mycobacterium tuberculosis complex (MTBC). Evolutionarily conserved polymorphisms in PhoPR from Mycobacterium africanum, M. bovis, or M. tuberculosis H37Ra result in loss of functional phenotypes. Interestingly, some members of the MTBC have acquired compensatory mutations to counteract these polymorphisms and, probably, to maintain their pathogenic potential. Some of these compensatory mutations include the insertion of the IS6110 element upstream from phoPR in a particular M. bovis strain that is able to transmit between humans or polymorphisms in M. africanum and M. bovis that affect the regulatory region of the espACD operon, allowing PhoPR-independent ESAT-6 secretion. This review highlights the increasing knowledge of the significance of PhoPR in the evolution of the MTBC and its potential application in the construction of new attenuated vaccines based on phoPR inactivation. In this context, the live attenuated vaccine MTBVAC, based on a phoP fadD26 deletion mutant of M. tuberculosis, is the first vaccine of this kind to successfully enter into clinical development, representing a historic milestone in the field of human vaccinology.
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60
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Wassermann R, Gulen MF, Sala C, Perin SG, Lou Y, Rybniker J, Schmid-Burgk JL, Schmidt T, Hornung V, Cole ST, Ablasser A. Mycobacterium tuberculosis Differentially Activates cGAS- and Inflammasome-Dependent Intracellular Immune Responses through ESX-1. Cell Host Microbe 2015; 17:799-810. [PMID: 26048138 DOI: 10.1016/j.chom.2015.05.003] [Citation(s) in RCA: 281] [Impact Index Per Article: 31.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Revised: 03/02/2015] [Accepted: 04/15/2015] [Indexed: 12/21/2022]
Abstract
Cytosolic detection of microbial products is essential for the initiation of an innate immune response against intracellular pathogens such as Mycobacterium tuberculosis (Mtb). During Mtb infection of macrophages, activation of cytosolic surveillance pathways is dependent on the mycobacterial ESX-1 secretion system and leads to type I interferon (IFN) and interleukin-1β (IL-1β) production. Whereas the inflammasome regulates IL-1β secretion, the receptor(s) responsible for the activation of type I IFNs has remained elusive. We demonstrate that the cytosolic DNA sensor cyclic GMP-AMP synthase (cGAS) is essential for initiating an IFN response to Mtb infection. cGAS associates with Mtb DNA in the cytosol to stimulate cyclic GAMP (cGAMP) synthesis. Notably, activation of cGAS-dependent cytosolic host responses can be uncoupled from inflammasome activation by modulating the secretion of ESX-1 substrates. Our findings identify cGAS as an innate sensor of Mtb and provide insight into how ESX-1 controls the activation of specific intracellular recognition pathways.
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Affiliation(s)
- Ruth Wassermann
- Global Health Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Muhammet F Gulen
- Global Health Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Claudia Sala
- Global Health Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Sonia Garcia Perin
- Global Health Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Ye Lou
- Global Health Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Jan Rybniker
- Global Health Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland; First Department of Internal Medicine, University of Cologne, 50937 Cologne, Germany
| | - Jonathan L Schmid-Burgk
- Institute for Molecular Medicine, University Hospital, University of Bonn, 53127 Bonn, Germany
| | - Tobias Schmidt
- Institute for Molecular Medicine, University Hospital, University of Bonn, 53127 Bonn, Germany
| | - Veit Hornung
- Institute for Molecular Medicine, University Hospital, University of Bonn, 53127 Bonn, Germany
| | - Stewart T Cole
- Global Health Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland.
| | - Andrea Ablasser
- Global Health Institute, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland.
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61
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Abstract
Bacterial secretion systems are sophisticated molecular machines that fulfil a wide range of important functions, which reach from export/secretion of essential proteins or virulence factors to the implication in conjugation processes. In contrast to the widely distributed Sec and Twin Arginine Translocation (TAT) systems, the recently identified ESX/type VII systems show a more restricted distribution and are typical for mycobacteria and other high-GC Actinobacteria. Similarly, type VII-like secretion systems have been described in low-GC Gram-positive bacteria belonging to the phylum Firmicutes. While the most complex organization of type VII secretion systems currently known is found in slow-growing mycobacteria, which harbour up to 5 chromosomal-encoded systems (ESX-1 to ESX-5), much simpler organization is reported for type VII-like systems in Firmicutes. In this chapter, we describe common and divergent features of type VII- and type VII-like secretion pathways and also comment on their biological key roles, many of which are related to species-/genus-specific host-pathogen interactions and/or virulence mechanisms.
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62
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Cao G, Howard ST, Zhang P, Wang X, Chen XL, Samten B, Pang X. EspR, a regulator of the ESX-1 secretion system in Mycobacterium tuberculosis, is directly regulated by the two-component systems MprAB and PhoPR. MICROBIOLOGY-SGM 2014; 161:477-89. [PMID: 25536998 DOI: 10.1099/mic.0.000023] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The regulatory mechanisms that control the ESX-1 secretion system, a key player in the pathogenesis of Mycobacterium tuberculosis, have not been fully elucidated. However, factors that regulate the ESX-1 substrate EspA usually affect ESX-1 function. Previous studies showed that espA is directly regulated by the nucleoid-associated protein EspR and the two-component system (TCS) MprAB. The PhoPR TCS also activates espA, but the direct target of PhoP was unknown. In this report, we reveal that EspR is directly regulated by MprA and PhoP-Rv, but not by PhoP-Ra. PhoP-Rv and MprA binding sites in the espR promoter were determined by gel-shift and DNase I footprinting assays, which identified a PhoP-protected region centred approximately 205 bp before the espR start codon and that encompasses MprA Region-1, one of two MprA-protected regions. MprA Region-2 is located approximately 60 bp downstream of MprA Region-1 and overlaps a known EspR binding site. Nucleotides essential for the binding of PhoP and/or MprA were identified through site-directed DNA mutagenesis. Our studies also indicate that MprA Region-2, but not MprA Region-1/PhoP region, is required for the full expression of espR. Recombinant strains carrying mutations at MprA Region-2 exhibited lower transcription levels for espR, espA and espD, and had reduced EspR and EspA levels in cell lysates. These findings indicate that EspR may mediate the regulatory effect of PhoPR and MprAB, and provide more insight into the mechanisms underlying ESX-1 control.
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Affiliation(s)
- Guangxiang Cao
- State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100, PR China Shandong Medicinal Biotechnology Center, Jinan, 250062, PR China
| | - Susan T Howard
- Department of Microbiology, University of Texas Health Science Center at Tyler, Tyler, TX 75708, USA
| | - Peipei Zhang
- State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100, PR China
| | - Xisheng Wang
- Pulmonary Immunology, University of Texas Health Science Center at Tyler, Tyler, TX 75708, USA
| | - Xiu-Lan Chen
- State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100, PR China
| | - Buka Samten
- Pulmonary Immunology, University of Texas Health Science Center at Tyler, Tyler, TX 75708, USA
| | - Xiuhua Pang
- State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100, PR China
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63
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He X, Wang S. DNA consensus sequence motif for binding response regulator PhoP, a virulence regulator of Mycobacterium tuberculosis. Biochemistry 2014; 53:8008-20. [PMID: 25434965 PMCID: PMC4283936 DOI: 10.1021/bi501019u] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
![]()
Tuberculosis has reemerged as a serious
threat to human health
because of the increasing prevalence of drug-resistant strains and
synergetic infection with HIV, prompting an urgent need for new and
more efficient treatments. The PhoP–PhoR two-component system
of Mycobacterium tuberculosis plays an important
role in the virulence of the pathogen and thus represents a potential
drug target. To study the mechanism of gene transcription regulation
by response regulator PhoP, we identified a high-affinity DNA sequence
for PhoP binding using systematic evolution of ligands by exponential
enrichment. The sequence contains a direct repeat of two 7 bp motifs
separated by a 4 bp spacer, TCACAGC(N4)TCACAGC. The specificity
of the direct-repeat sequence for PhoP binding was confirmed by isothermal
titration calorimetry and electrophoretic mobility shift assays. PhoP
binds to the direct repeat as a dimer in a highly cooperative manner.
We found many genes previously identified to be regulated by PhoP
that contain the direct-repeat motif in their promoter sequences.
Synthetic DNA fragments at the putative promoter-binding sites bind
PhoP with variable affinity, which is related to the number of mismatches
in the 7 bp motifs, the positions of the mismatches, and the spacer
and flanking sequences. Phosphorylation of PhoP increases the affinity
but does not change the specificity of DNA binding. Overall, our results
confirm the direct-repeat sequence as the consensus motif for PhoP
binding and thus pave the way for identification of PhoP directly
regulated genes in different mycobacterial genomes.
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Affiliation(s)
- Xiaoyuan He
- Department of Biochemistry and Molecular Biology, Uniformed Services University of the Health Sciences , Bethesda, Maryland 20814, United States
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64
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Boritsch EC, Supply P, Honoré N, Seeman T, Stinear TP, Brosch R. A glimpse into the past and predictions for the future: the molecular evolution of the tuberculosis agent. Mol Microbiol 2014; 93:835-52. [DOI: 10.1111/mmi.12720] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/14/2014] [Indexed: 02/01/2023]
Affiliation(s)
- Eva C. Boritsch
- Institut Pasteur; Unit for Integrated Mycobacterial Pathogenomics; Paris France
| | - Philip Supply
- INSERM U1019; Lille France
- CNRS UMR 8204; Lille France
- University of Lille Nord de France; Lille France
- Institut Pasteur de Lille; Center for Infection and Immunity of Lille; Lille France
| | - Nadine Honoré
- Institut Pasteur; Unit for Integrated Mycobacterial Pathogenomics; Paris France
| | - Torsten Seeman
- Victorian Bioinformatics Consortium; Monash University; Clayton Victoria Australia
| | - Timothy P. Stinear
- Department of Microbiology and Immunology; University of Melbourne; Parkville Victoria Australia
| | - Roland Brosch
- Institut Pasteur; Unit for Integrated Mycobacterial Pathogenomics; Paris France
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