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Bockman MR, Engelhart CA, Cramer JD, Howe MD, Mishra NK, Zimmerman M, Larson P, Alvarez-Cabrera N, Park SW, Boshoff HIM, Bean JM, Young VG, Ferguson DM, Dartois V, Jarrett JT, Schnappinger D, Aldrich CC. Investigation of ( S)-(-)-Acidomycin: A Selective Antimycobacterial Natural Product That Inhibits Biotin Synthase. ACS Infect Dis 2019; 5:598-617. [PMID: 30652474 DOI: 10.1021/acsinfecdis.8b00345] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The synthesis, absolute stereochemical configuration, complete biological characterization, mechanism of action and resistance, and pharmacokinetic properties of ( S)-(-)-acidomycin are described. Acidomycin possesses promising antitubercular activity against a series of contemporary drug susceptible and drug-resistant M. tuberculosis strains (minimum inhibitory concentrations (MICs) = 0.096-6.2 μM) but is inactive against nontuberculosis mycobacteria and Gram-positive and Gram-negative pathogens (MICs > 1000 μM). Complementation studies with biotin biosynthetic pathway intermediates and subsequent biochemical studies confirmed acidomycin inhibits biotin synthesis with a Ki of approximately 1 μM through the competitive inhibition of biotin synthase (BioB) and also stimulates unproductive cleavage of S-adenosyl-l-methionine (SAM) to generate the toxic metabolite 5'-deoxyadenosine. Cell studies demonstrate acidomycin selectively accumulates in M. tuberculosis providing a mechanistic basis for the observed antibacterial activity. The development of spontaneous resistance by M. tuberculosis to acidomycin was difficult, and only low-level resistance to acidomycin was observed by overexpression of BioB. Collectively, the results provide a foundation to advance acidomycin and highlight BioB as a promising target.
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Affiliation(s)
- Matthew R. Bockman
- Department of Medicinal Chemistry, University of Minnesota, 308 Harvard Street SE, Minneapolis, Minnesota 55455, United States
| | - Curtis A. Engelhart
- Department of Microbiology and Immunology, Weill Cornell Medical College, 1300 York Avenue, New York, New York 10021, United States
| | - Julia D. Cramer
- Department of Chemistry, University of Hawaii at Manoa, 2545 McCarthy Mall, Honolulu, Hawaii 96822, United States
| | - Michael D. Howe
- Department of Medicinal Chemistry, University of Minnesota, 308 Harvard Street SE, Minneapolis, Minnesota 55455, United States
| | - Neeraj K. Mishra
- Department of Medicinal Chemistry, University of Minnesota, 308 Harvard Street SE, Minneapolis, Minnesota 55455, United States
| | - Matthew Zimmerman
- Public Health Research Institute, Rutgers, The State University of New Jersey, 225 Warren Street, Newark, New Jersey 07103, United States
| | - Peter Larson
- Department of Medicinal Chemistry, University of Minnesota, 308 Harvard Street SE, Minneapolis, Minnesota 55455, United States
| | - Nadine Alvarez-Cabrera
- Public Health Research Institute, Rutgers, The State University of New Jersey, 225 Warren Street, Newark, New Jersey 07103, United States
| | - Sae Woong Park
- Department of Microbiology and Immunology, Weill Cornell Medical College, 1300 York Avenue, New York, New York 10021, United States
| | - Helena I. M. Boshoff
- Tuberculosis Research Section, Laboratory of Clinical Immunology and Microbiology, NIAID, NIH, 5601 Fishers Lane, Bethesda, Maryland 20892, United States
| | - James M. Bean
- Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, New York 10065, United States
| | - Victor G. Young
- X-Ray Crystallographic Laboratory, LeClaire-Dow Chemical Instrumentation Facility, Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, United States
| | - David M. Ferguson
- Department of Medicinal Chemistry, University of Minnesota, 308 Harvard Street SE, Minneapolis, Minnesota 55455, United States
| | - Veronique Dartois
- Public Health Research Institute, Rutgers, The State University of New Jersey, 225 Warren Street, Newark, New Jersey 07103, United States
| | - Joseph T. Jarrett
- Department of Chemistry, University of Hawaii at Manoa, 2545 McCarthy Mall, Honolulu, Hawaii 96822, United States
| | - Dirk Schnappinger
- Department of Microbiology and Immunology, Weill Cornell Medical College, 1300 York Avenue, New York, New York 10021, United States
| | - Courtney C. Aldrich
- Department of Medicinal Chemistry, University of Minnesota, 308 Harvard Street SE, Minneapolis, Minnesota 55455, United States
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Freire DM, Gutierrez C, Garza-Garcia A, Grabowska AD, Sala AJ, Ariyachaokun K, Panikova T, Beckham KSH, Colom A, Pogenberg V, Cianci M, Tuukkanen A, Boudehen YM, Peixoto A, Botella L, Svergun DI, Schnappinger D, Schneider TR, Genevaux P, de Carvalho LPS, Wilmanns M, Parret AHA, Neyrolles O. An NAD + Phosphorylase Toxin Triggers Mycobacterium tuberculosis Cell Death. Mol Cell 2019; 73:1282-1291.e8. [PMID: 30792174 PMCID: PMC6436930 DOI: 10.1016/j.molcel.2019.01.028] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Revised: 11/13/2018] [Accepted: 01/18/2019] [Indexed: 01/13/2023]
Abstract
Toxin-antitoxin (TA) systems regulate fundamental cellular processes in bacteria and represent potential therapeutic targets. We report a new RES-Xre TA system in multiple human pathogens, including Mycobacterium tuberculosis. The toxin, MbcT, is bactericidal unless neutralized by its antitoxin MbcA. To investigate the mechanism, we solved the 1.8 Å-resolution crystal structure of the MbcTA complex. We found that MbcT resembles secreted NAD+-dependent bacterial exotoxins, such as diphtheria toxin. Indeed, MbcT catalyzes NAD+ degradation in vitro and in vivo. Unexpectedly, the reaction is stimulated by inorganic phosphate, and our data reveal that MbcT is a NAD+ phosphorylase. In the absence of MbcA, MbcT triggers rapid M. tuberculosis cell death, which reduces mycobacterial survival in macrophages and prolongs the survival of infected mice. Our study expands the molecular activities employed by bacterial TA modules and uncovers a new class of enzymes that could be exploited to treat tuberculosis and other infectious diseases.
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Affiliation(s)
- Diana Mendes Freire
- European Molecular Biology Laboratory, Hamburg Unit, Notkestraße 85, 22607 Hamburg, Germany
| | - Claude Gutierrez
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, 205 route de Narbonne, 31400 Toulouse, France
| | - Acely Garza-Garcia
- Mycobacterial Metabolism and Antibiotic Research Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Anna D Grabowska
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, 205 route de Narbonne, 31400 Toulouse, France
| | - Ambre J Sala
- Laboratoire de Microbiologie et Génétique Moléculaires, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, 118 route de Narbonne, 31400 Toulouse, France
| | - Kanchiyaphat Ariyachaokun
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, 205 route de Narbonne, 31400 Toulouse, France
| | - Terezie Panikova
- European Molecular Biology Laboratory, Hamburg Unit, Notkestraße 85, 22607 Hamburg, Germany
| | - Katherine S H Beckham
- European Molecular Biology Laboratory, Hamburg Unit, Notkestraße 85, 22607 Hamburg, Germany
| | - André Colom
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, 205 route de Narbonne, 31400 Toulouse, France
| | - Vivian Pogenberg
- European Molecular Biology Laboratory, Hamburg Unit, Notkestraße 85, 22607 Hamburg, Germany
| | - Michele Cianci
- European Molecular Biology Laboratory, Hamburg Unit, Notkestraße 85, 22607 Hamburg, Germany
| | - Anne Tuukkanen
- European Molecular Biology Laboratory, Hamburg Unit, Notkestraße 85, 22607 Hamburg, Germany
| | - Yves-Marie Boudehen
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, 205 route de Narbonne, 31400 Toulouse, France
| | - Antonio Peixoto
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, 205 route de Narbonne, 31400 Toulouse, France
| | - Laure Botella
- Department of Microbiology and Immunology, Weill Cornell Medical College, 1300 York Avenue, New York, NY 10065, USA
| | - Dmitri I Svergun
- European Molecular Biology Laboratory, Hamburg Unit, Notkestraße 85, 22607 Hamburg, Germany
| | - Dirk Schnappinger
- Department of Microbiology and Immunology, Weill Cornell Medical College, 1300 York Avenue, New York, NY 10065, USA
| | - Thomas R Schneider
- European Molecular Biology Laboratory, Hamburg Unit, Notkestraße 85, 22607 Hamburg, Germany
| | - Pierre Genevaux
- Laboratoire de Microbiologie et Génétique Moléculaires, Centre de Biologie Intégrative, Université de Toulouse, CNRS, UPS, 118 route de Narbonne, 31400 Toulouse, France
| | - Luiz Pedro Sorio de Carvalho
- Mycobacterial Metabolism and Antibiotic Research Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Matthias Wilmanns
- European Molecular Biology Laboratory, Hamburg Unit, Notkestraße 85, 22607 Hamburg, Germany; University Hamburg Medical Centre Hamburg-Eppendorf, Martinistraße 52, 20246 Hamburg, Germany
| | - Annabel H A Parret
- European Molecular Biology Laboratory, Hamburg Unit, Notkestraße 85, 22607 Hamburg, Germany.
| | - Olivier Neyrolles
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, 205 route de Narbonne, 31400 Toulouse, France.
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53
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Counoupas C, Triccas JA, Britton WJ. Deciphering protective immunity against tuberculosis: implications for vaccine development. Expert Rev Vaccines 2019; 18:353-364. [PMID: 30793629 DOI: 10.1080/14760584.2019.1585246] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
INTRODUCTION The development of more effective tuberculosis (TB) vaccines is essential for the global control of TB. Recently, there have been major advances in the field, but an important hindrance remains the lack of correlates of protection against TB. This requires each vaccine candidate to undergo clinical efficacy trials based on data from animal protection studies, but the results from animal models do not necessarily predict efficacy in humans. AREAS COVERED In this review we summarize our current knowledge of immune mechanisms that may contribute to protective immunity against TB following vaccination and relate these to protective efficacy in animal models and recent clinical trials. Although some initial trials did not reproduce protection against TB in humans, recent trials have demonstrated promising efficacy for three vaccine approaches. EXPERT OPINION Although CD4+ T lymphocytes are essential for protection against TB, there is no clear correlation between conventional CD4+ or CD8+ T cell responses and protective efficacy of TB vaccines. Recent attention has focused on other immune responses, including donor unrestricted T cells, B lymphocytes, and antibodies. Prospective studies on samples from vaccinated individuals protected in recent trials will allow evaluation of these alternative immune mechanisms as potential correlates of protection.
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Affiliation(s)
- Claudio Counoupas
- a Tuberculosis Research Program Centenary Institute , The University of Sydney , Camperdown , NSW , Australia.,b The University of Sydney , Central Clinical School Faculty of Medicine and Health , Sydney , NSW , Australia
| | - James A Triccas
- a Tuberculosis Research Program Centenary Institute , The University of Sydney , Camperdown , NSW , Australia
| | - Warwick J Britton
- a Tuberculosis Research Program Centenary Institute , The University of Sydney , Camperdown , NSW , Australia.,b The University of Sydney , Central Clinical School Faculty of Medicine and Health , Sydney , NSW , Australia
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Abstract
Antibiotic tolerance, the capacity of genetically susceptible bacteria to survive the lethal effects of antibiotic treatment, plays a critical and underappreciated role in the disease burden of bacterial infections. Here, we take a pathogen-by-pathogen approach to illustrate the clinical significance of antibiotic tolerance and discuss how the physiology of specific pathogens in their infection environments impacts the mechanistic underpinnings of tolerance. We describe how these insights are leading to the development of species-specific therapeutic strategies for targeting antibiotic tolerance and highlight experimental platforms that are enabling us to better understand the complexities of drug-tolerant pathogens in in vivo settings.
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Affiliation(s)
- Sylvain Meylan
- Department of Biomedicine, Basel University Hospital, Basel, CH-4031, Switzerland; Division of Infectious Diseases and Hospital Epidemiology, Basel University Hospital, Basel, CH-4031, Switzerland; Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA 02115, USA
| | - Ian W Andrews
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA 02115, USA; Institute for Medical Engineering & Science, Department of Biological Engineering, and Synthetic Biology Center, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - James J Collins
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA 02115, USA; Institute for Medical Engineering & Science, Department of Biological Engineering, and Synthetic Biology Center, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA; Harvard-MIT Program in Health Sciences and Technology, Cambridge, MA 02139, USA.
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55
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Rittershaus ESC, Baek SH, Krieger IV, Nelson SJ, Cheng YS, Nambi S, Baker RE, Leszyk JD, Shaffer SA, Sacchettini JC, Sassetti CM. A Lysine Acetyltransferase Contributes to the Metabolic Adaptation to Hypoxia in Mycobacterium tuberculosis. Cell Chem Biol 2018; 25:1495-1505.e3. [PMID: 30318462 PMCID: PMC6309504 DOI: 10.1016/j.chembiol.2018.09.009] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Revised: 05/14/2018] [Accepted: 09/12/2018] [Indexed: 01/07/2023]
Abstract
Upon inhibition of respiration, which occurs in hypoxic or nitric oxide-containing host microenvironments, Mycobacterium tuberculosis (Mtb) adopts a non-replicating "quiescent" state and becomes relatively unresponsive to antibiotic treatment. We used comprehensive mutant fitness analysis to identify regulatory and metabolic pathways that are essential for the survival of quiescent Mtb. This genetic study identified a protein acetyltransferase (Mt-Pat/Rv0998) that promoted survival and altered the flux of carbon from oxidative to reductive tricarboxylic acid (TCA) reactions. Reductive TCA requires malate dehydrogenase (MDH) and maintains the redox state of the NAD+/NADH pool. Genetic or chemical inhibition of MDH resulted in rapid cell death in both hypoxic cultures and in murine lung. These phenotypic data, in conjunction with significant structural differences between human and mycobacterial MDH enzymes that could be exploited for drug development, suggest a new strategy for eradicating quiescent bacteria.
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Affiliation(s)
- Emily S. C. Rittershaus
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School. Worcester, MA. 01650 USA
| | - Seung-Hun Baek
- Department of Microbiology, Yonsei University College of Medicine, Seoul Korea
| | - Inna V. Krieger
- Department of Biochemistry and Biophysics. Texas A&M University. College Station, TX. 77843 USA
| | - Samantha J. Nelson
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School. Worcester, MA. 01650 USA
| | - Yu-Shan Cheng
- Department of Biochemistry and Biophysics. Texas A&M University. College Station, TX. 77843 USA
| | - Subhalaxmi Nambi
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School. Worcester, MA. 01650 USA
| | - Richard E. Baker
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School. Worcester, MA. 01650 USA
| | - John D. Leszyk
- Proteomics and Mass Spectrometry Facility, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA. 01650 USA
| | - Scott A. Shaffer
- Proteomics and Mass Spectrometry Facility, Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA. 01650 USA
| | - James C. Sacchettini
- Department of Biochemistry and Biophysics. Texas A&M University. College Station, TX. 77843 USA
| | - Christopher M. Sassetti
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School. Worcester, MA. 01650 USA
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56
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Puffal J, Mayfield JA, Moody DB, Morita YS. Demethylmenaquinone Methyl Transferase Is a Membrane Domain-Associated Protein Essential for Menaquinone Homeostasis in Mycobacterium smegmatis. Front Microbiol 2018; 9:3145. [PMID: 30619211 PMCID: PMC6305584 DOI: 10.3389/fmicb.2018.03145] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Accepted: 12/04/2018] [Indexed: 12/20/2022] Open
Abstract
The intracellular membrane domain (IMD) in mycobacteria is a spatially distinct region of the plasma membrane with diverse functions. Previous comparative proteomic analysis of the IMD suggested that menaquinone biosynthetic enzymes are associated with this domain. In the present study, we determined the subcellular site of these enzymes using sucrose density gradient fractionation. We found that the last two enzymes, the methyltransferase MenG, and the reductase MenJ, are associated with the IMD in Mycobacterium smegmatis. MenA, the prenyltransferase that mediates the first membrane-associated step of the menaquinone biosynthesis, is associated with the conventional plasma membrane. For MenG, we additionally showed the polar enrichment of the fluorescent protein fusion colocalizing with an IMD marker protein in situ. To start dissecting the roles of IMD-associated enzymes, we further tested the physiological significance of MenG. The deletion of menG at the endogenous genomic loci was possible only when an extra copy of the gene was present, indicating that it is an essential gene in M. smegmatis. Using a tetracycline-inducible switch, we achieved gradual and partial depletion of MenG over three consecutive 24 h sub-cultures. This partial MenG depletion resulted in progressive slowing of growth, which corroborated the observation that menG is an essential gene. Upon MenG depletion, there was a significant accumulation of MenG substrate, demethylmenaquinone, even though the cellular level of menaquinone, the reaction product, was unaffected. Furthermore, the growth retardation was coincided with a lower oxygen consumption rate and ATP accumulation. These results imply a previously unappreciated role of MenG in regulating menaquinone homeostasis within the complex spatial organization of mycobacterial plasma membrane.
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Affiliation(s)
- Julia Puffal
- Department of Microbiology, University of Massachusetts, Amherst, MA, United States
| | - Jacob A. Mayfield
- Division of Rheumatology, Immunology and Allergy, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, United States
| | - D. Branch Moody
- Division of Rheumatology, Immunology and Allergy, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, United States
| | - Yasu S. Morita
- Department of Microbiology, University of Massachusetts, Amherst, MA, United States
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57
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Murphy KC, Nelson SJ, Nambi S, Papavinasasundaram K, Baer CE, Sassetti CM. ORBIT: a New Paradigm for Genetic Engineering of Mycobacterial Chromosomes. mBio 2018; 9:e01467-18. [PMID: 30538179 PMCID: PMC6299477 DOI: 10.1128/mbio.01467-18] [Citation(s) in RCA: 67] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Accepted: 10/19/2018] [Indexed: 11/20/2022] Open
Abstract
Two efficient recombination systems were combined to produce a versatile method for chromosomal engineering that obviates the need to prepare double-stranded DNA (dsDNA) recombination substrates. A synthetic "targeting oligonucleotide" is incorporated into the chromosome via homologous recombination mediated by the phage Che9c RecT annealase. This oligonucleotide contains a site-specific recombination site for the directional Bxb1 integrase (Int), which allows the simultaneous integration of a "payload plasmid" that contains a cognate recombination site and a selectable marker. The targeting oligonucleotide and payload plasmid are cotransformed into a RecT- and Int-expressing strain, and drug-resistant homologous recombinants are selected in a single step. A library of reusable target-independent payload plasmids is available to generate gene knockouts, promoter replacements, or C-terminal tags. This new system is called ORBIT (for "oligonucleotide-mediated recombineering followed by Bxb1 integrase targeting") and is ideally suited for the creation of libraries consisting of large numbers of deletions, insertions, or fusions in a bacterial chromosome. We demonstrate the utility of this "drag and drop" strategy by the construction of insertions or deletions in over 100 genes in Mycobacteriumtuberculosis and M. smegmatisIMPORTANCE We sought to develop a system that could increase the usefulness of oligonucleotide-mediated recombineering of bacterial chromosomes by expanding the types of modifications generated by an oligonucleotide (i.e., insertions and deletions) and by making recombinant formation a selectable event. This paper describes such a system for use in M. smegmatis and M. tuberculosis By incorporating a single-stranded DNA (ssDNA) version of the phage Bxb1 attP site into the oligonucleotide and coelectroporating it with a nonreplicative plasmid that carries an attB site and a drug selection marker, we show both formation of a chromosomal attP site and integration of the plasmid in a single transformation. No target-specific dsDNA substrates are required. This system will allow investigators studying mycobacterial diseases, including tuberculosis, to easily generate multiple mutants for analysis of virulence factors, identification of new drug targets, and development of new vaccines.
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Affiliation(s)
- Kenan C Murphy
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Samantha J Nelson
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Subhalaxmi Nambi
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Kadamba Papavinasasundaram
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Christina E Baer
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Christopher M Sassetti
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, Massachusetts, USA
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Chhotaray C, Tan Y, Mugweru J, Islam MM, Adnan Hameed HM, Wang S, Lu Z, Wang C, Li X, Tan S, Liu J, Zhang T. Advances in the development of molecular genetic tools for Mycobacterium tuberculosis. J Genet Genomics 2018; 45:S1673-8527(18)30114-0. [PMID: 29941353 DOI: 10.1016/j.jgg.2018.06.003] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Mycobacterium tuberculosis, a clinically relevant Gram-positive bacterium of great clinical relevance, is a lethal pathogen owing to its complex physiological characteristics and development of drug resistance. Several molecular genetic tools have been developed in the past few decades to study this microorganism. These tools have been instrumental in understanding how M. tuberculosis became a successful pathogen. Advanced molecular genetic tools have played a significant role in exploring the complex pathways involved in M. tuberculosis pathogenesis. Here, we review various molecular genetic tools used in the study of M. tuberculosis. Further, we discuss the applications of clustered regularly interspaced short palindromic repeat interference (CRISPRi), a novel technology recently applied in M. tuberculosis research to study target gene functions. Finally, prospective outcomes of the applications of molecular techniques in the field of M. tuberculosis genetic research are also discussed.
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Affiliation(s)
- Chiranjibi Chhotaray
- State Key Laboratory of Respiratory Disease, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yaoju Tan
- State Key Laboratory of Respiratory Disease, Department of Clinical Laboratory, Guangzhou Chest Hospital, Guangzhou 510095, China
| | - Julius Mugweru
- State Key Laboratory of Respiratory Disease, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China; University of Chinese Academy of Sciences, Beijing 100049, China; Department of Biological Sciences, University of Embu, P.O Box 6 -60100, Embu, Kenya
| | - Md Mahmudul Islam
- State Key Laboratory of Respiratory Disease, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - H M Adnan Hameed
- State Key Laboratory of Respiratory Disease, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Shuai Wang
- State Key Laboratory of Respiratory Disease, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhili Lu
- State Key Laboratory of Respiratory Disease, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China
| | - Changwei Wang
- State Key Laboratory of Respiratory Disease, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China
| | - Xinjie Li
- State Key Laboratory of Respiratory Disease, Department of Clinical Laboratory, Guangzhou Chest Hospital, Guangzhou 510095, China
| | - Shouyong Tan
- State Key Laboratory of Respiratory Disease, Department of Clinical Laboratory, Guangzhou Chest Hospital, Guangzhou 510095, China
| | - Jianxiong Liu
- State Key Laboratory of Respiratory Disease, Department of Clinical Laboratory, Guangzhou Chest Hospital, Guangzhou 510095, China.
| | - Tianyu Zhang
- State Key Laboratory of Respiratory Disease, Guangzhou Institutes of Biomedicine and Health, Chinese Academy of Sciences, Guangzhou 510530, China; University of Chinese Academy of Sciences, Beijing 100049, China.
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Mycobacterium tuberculosis Pst/SenX3-RegX3 Regulates Membrane Vesicle Production Independently of ESX-5 Activity. mBio 2018; 9:mBio.00778-18. [PMID: 29895636 PMCID: PMC6016242 DOI: 10.1128/mbio.00778-18] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Mycobacterium tuberculosis releases membrane vesicles (MV) that modulate host immune responses and aid in iron acquisition, although they may have additional unappreciated functions. MV production appears to be a regulated process, but virR remains the only characterized genetic regulator of vesiculogenesis. Here, we present data supporting a role for the M. tuberculosis Pst/SenX3-RegX3 signal transduction system in regulating MV production. Deletion of pstA1, which encodes a transmembrane component of the phosphate-specific transport (Pst) system, causes constitutive activation of the SenX3-RegX3 two-component system, leading to increased protein secretion via the specialized ESX-5 type VII secretion system. Using proteomic mass spectrometry, we identified several additional proteins hyper-secreted by the ΔpstA1 mutant, including LpqH, an MV-associated lipoprotein. Nanoparticle tracking analysis revealed a 15-fold increase in MV production by the ΔpstA1 mutant. Both hyper-secretion of LpqH and increased MV release required RegX3 but were independent of VirR, suggesting that Pst/SenX3-RegX3 controls MV release by a novel mechanism. Prior proteomic analysis identified ESX-5 substrates associated with MV. We therefore hypothesized that MV release requires ESX-5 activity. We constructed strains that conditionally express eccD5, which encodes the predicted ESX-5 transmembrane channel. Upon EccD5 depletion, we observed reduced secretion of the ESX-5 substrates EsxN and PPE41, but MV release was unaffected. Our data suggest that ESX-5 does not affect vesicle production and imply that further characterization of the Pst/SenX3-RegX3 regulon might reveal novel mechanisms of M. tuberculosis vesicle biogenesis. In Gram-negative bacteria, MV derived from the outer membrane have diverse functions in bacterial physiology and pathogenesis, and several factors regulating their production have been identified. Though Gram-positive bacteria and mycobacteria that lack an outer membrane also produce vesicles with described roles in pathogenesis, the mechanisms of MV biogenesis in these organisms remain poorly characterized. Defining mechanisms of MV biogenesis might yield significant insights into the importance of MV production during infection. In M. tuberculosis, only a single genetic element, virR, is known to regulate MV production. Our work reveals that the Pst/SenX3-RegX3 signal transduction system is a novel regulator of MV biogenesis that controls MV production by a mechanism that is independent of both VirR and activation of the specialized ESX-5 protein secretion system. Understanding which genes in the RegX3 regulon cause increased MV production might reveal novel molecular mechanisms of MV release.
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60
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Matern WM, Rifat D, Bader JS, Karakousis PC. Gene Enrichment Analysis Reveals Major Regulators of Mycobacterium tuberculosis Gene Expression in Two Models of Antibiotic Tolerance. Front Microbiol 2018; 9:610. [PMID: 29670589 PMCID: PMC5893760 DOI: 10.3389/fmicb.2018.00610] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2017] [Accepted: 03/15/2018] [Indexed: 01/10/2023] Open
Abstract
The development of antibiotic tolerance is believed to be a major factor in the lengthy duration of current tuberculosis therapies. In the current study, we have modeled antibiotic tolerance in vitro by exposing Mycobacterium tuberculosis to two distinct stress conditions: progressive hypoxia and nutrient starvation [phosphate-buffered saline (PBS)]. We then studied the bacterial transcriptional response using RNA-seq and employed a bioinformatics approach to identify important transcriptional regulators, which was facilitated by a novel Regulon Enrichment Test (RET). A total of 17 transcription factor (TF) regulons were enriched in the hypoxia gene set and 16 regulons were enriched in the nutrient starvation, with 12 regulons enriched in both conditions. Using the same approach to analyze previously published gene expression datasets, we found that three M. tuberculosis regulons (Rv0023, SigH, and Crp) were commonly induced in both stress conditions and were also among the regulons enriched in our data. These regulators are worthy of further study to determine their potential role in the development and maintenance of antibiotic tolerance in M. tuberculosis following stress exposure.
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Affiliation(s)
- William M Matern
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States.,Department of Biomedical Engineering and High-Throughput Biology Center, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Dalin Rifat
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Joel S Bader
- Department of Biomedical Engineering and High-Throughput Biology Center, Johns Hopkins University School of Medicine, Baltimore, MD, United States
| | - Petros C Karakousis
- Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States.,Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD, United States
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61
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Wang X, Dowd CS. The Methylerythritol Phosphate Pathway: Promising Drug Targets in the Fight against Tuberculosis. ACS Infect Dis 2018; 4:278-290. [PMID: 29390176 DOI: 10.1021/acsinfecdis.7b00176] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), is a severe infectious disease in need of new chemotherapies especially for drug-resistant cases. To meet the urgent requirement of new TB drugs with novel modes of action, the TB research community has been validating numerous targets from several biosynthetic pathways. The methylerythritol phosphate (MEP) pathway is utilized by Mtb for the biosynthesis of isopentenyl pyrophosphate (IPP) and its isomer dimethylallyl pyrophosphate (DMAPP), the universal five-carbon building blocks of isoprenoids. While being a common biosynthetic pathway in pathogens, the MEP pathway is completely absent in humans. Due to its unique presence in pathogens as well as the essentiality of the MEP pathway in Mtb, the enzymes in this pathway are promising targets for the development of new drugs against tuberculosis. In this Review, we discuss three enzymes in the MEP pathway: 1-deoxy-d-xylulose-5-phosphate synthase (DXS), 1-deoxy-d-xylulose-5-phosphate reductoisomerase (IspC/DXR), and 2 C-methyl-d-erythritol 2,4-cyclodiphosphate synthase (IspF), which appear to be the most promising antitubercular drug targets. Structural and mechanistic features of these enzymes are reviewed, as well as selected inhibitors that show promise as antitubercular agents.
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Affiliation(s)
- Xu Wang
- Department of Chemistry, George Washington University, 800 22nd Street NW, Washington, D.C. 20052, United States
| | - Cynthia S. Dowd
- Department of Chemistry, George Washington University, 800 22nd Street NW, Washington, D.C. 20052, United States
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62
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Abstract
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Current tuberculosis
(TB) drug development efforts are not sufficient
to end the global TB epidemic. Recent efforts have focused on the
development of whole-cell screening assays because biochemical, target-based
inhibitor screens during the last two decades have not delivered new
TB drugs. Mycobacterium tuberculosis (Mtb), the causative
agent of TB, encounters diverse microenvironments and can be found
in a variety of metabolic states in the human host. Due to the complexity
and heterogeneity of Mtb infection, no single model can fully recapitulate
the in vivo conditions in which Mtb is found in TB patients, and there
is no single “standard” screening condition to generate
hit compounds for TB drug development. However, current screening
assays have become more sophisticated as researchers attempt to mirror
the complexity of TB disease in the laboratory. In this review, we
describe efforts using surrogates and engineered strains of Mtb to
focus screens on specific targets. We explain model culture systems
ranging from carbon starvation to hypoxia, and combinations thereof,
designed to represent the microenvironment which Mtb encounters in
the human body. We outline ongoing efforts to model Mtb infection
in the lung granuloma. We assess these different models, their ability
to generate hit compounds, and needs for further TB drug development,
to provide direction for future TB drug discovery.
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Affiliation(s)
- Tianao Yuan
- Department of Chemistry, Stony Brook University , Stony Brook, New York 11794-3400, United States
| | - Nicole S Sampson
- Department of Chemistry, Stony Brook University , Stony Brook, New York 11794-3400, United States.,Stellenbosch Institute for Advanced Study (STIAS), Wallenberg Research Centre at Stellenbosch University , Stellenbosch 7600, South Africa
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63
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Abstract
Tuberculosis is responsible for more deaths worldwide than any other infectious disease. For anyone looking to learn more about this persistent public health threat, this conversational "frequently asked questions" style review addresses a breadth of questions. It offers a brief, somewhat opinionated, review of what is and is not known, particularly in light of how findings in the lab do or do not help inform the understanding of human tuberculosis.
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Affiliation(s)
- Kristine M Guinn
- Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Boston, Massachusetts, USA
| | - Eric J Rubin
- Department of Immunology and Infectious Diseases, Harvard T. H. Chan School of Public Health, Boston, Massachusetts, USA
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64
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Abstract
Coevolution of pathogens and host has led to many metabolic strategies employed by intracellular pathogens to deal with the immune response and the scarcity of food during infection. Simply put, bacterial pathogens are just looking for food. As a consequence, the host has developed strategies to limit nutrients for the bacterium by containment of the intruder in a pathogen-containing vacuole and/or by actively depleting nutrients from the intracellular space, a process called nutritional immunity. Since metabolism is a prerequisite for virulence, such pathways could potentially be good targets for antimicrobial therapies. In this chapter, we review the current knowledge about the in vivo diet of Mycobacterium tuberculosis, with a focus on amino acid and cofactors, discuss evidence for the bacilli's nutritionally independent lifestyle in the host, and evaluate strategies for new chemotherapeutic interventions.
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65
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Lazar N, Fay A, Nandakumar M, Boyle KE, Xavier J, Rhee K, Glickman MS. Control of biotin biosynthesis in mycobacteria by a pyruvate carboxylase dependent metabolic signal. Mol Microbiol 2017; 106:1018-1031. [PMID: 29052269 PMCID: PMC5916780 DOI: 10.1111/mmi.13865] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/12/2017] [Indexed: 01/15/2023]
Abstract
Biotin is an essential cofactor utilized by all domains of life, but only synthesized by bacteria, fungi and plants, making biotin biosynthesis a target for antimicrobial development. To understand biotin biosynthesis in mycobacteria, we executed a genetic screen in Mycobacterium smegmatis for biotin auxotrophs and identified pyruvate carboxylase (Pyc) as required for biotin biosynthesis. The biotin auxotrophy of the pyc::tn strain is due to failure to transcriptionally induce late stage biotin biosynthetic genes in low biotin conditions. Loss of bioQ, the repressor of biotin biosynthesis, in the pyc::tn strain reverted biotin auxotrophy, as did reconstituting the last step of the pathway through heterologous expression of BioB and provision of its substrate DTB. The role of Pyc in biotin regulation required its catalytic activities and could be supported by M. tuberculosis Pyc. Quantitation of the kinetics of depletion of biotinylated proteins after biotin withdrawal revealed that Pyc is the most rapidly depleted biotinylated protein and metabolomics revealed a broad metabolic shift in wild type cells upon biotin withdrawal which was blunted in cell lacking Pyc. Our data indicate that mycobacterial cells monitor biotin sufficiency through a metabolic signal generated by dysfunction of a biotinylated protein of central metabolism.
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Affiliation(s)
- Nathaniel Lazar
- Immunology Program, Memorial Sloan Kettering Cancer Center, New York, New York, USA
- Program in Immunology and Microbial Pathogenesis, Weill-Cornell Graduate School of Medical Sciences, New York, New York, USA
| | - Allison Fay
- Immunology Program, Memorial Sloan Kettering Cancer Center, New York, New York, USA
| | | | - Kerry E. Boyle
- Program in Immunology and Microbial Pathogenesis, Weill-Cornell Graduate School of Medical Sciences, New York, New York, USA
- Program in Computational Biology, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA
| | - Joao Xavier
- Program in Computational Biology, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, New York, NY 10065, USA
| | - Kyu Rhee
- Program in Immunology and Microbial Pathogenesis, Weill-Cornell Graduate School of Medical Sciences, New York, New York, USA
- Weill-Cornell Medical College, New York, New York, USA
| | - Michael S. Glickman
- Immunology Program, Memorial Sloan Kettering Cancer Center, New York, New York, USA
- Program in Immunology and Microbial Pathogenesis, Weill-Cornell Graduate School of Medical Sciences, New York, New York, USA
- Infectious Diseases Service, Department of Medicine, Memorial Sloan Kettering Cancer Center, New York, New York, USA
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66
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Boldrin F, Degiacomi G, Serafini A, Kolly GS, Ventura M, Sala C, Provvedi R, Palù G, Cole ST, Manganelli R. Promoter mutagenesis for fine-tuning expression of essential genes in Mycobacterium tuberculosis. Microb Biotechnol 2017; 11:238-247. [PMID: 29076636 PMCID: PMC5743821 DOI: 10.1111/1751-7915.12875] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Revised: 09/05/2017] [Accepted: 09/25/2017] [Indexed: 02/04/2023] Open
Abstract
A range of regulated gene expression systems has been developed for mycobacteria in the last few years to facilitate the study of essential genes, validate novel drug targets and evaluate their vulnerability. Among these, the TetR/Pip-OFF repressible promoter system was successfully used in several mycobacterial species both in vitro and in vivo. In the first version of the system, the repressible promoter was Pptr , a strong Pip-repressible promoter of Streptomyces pristinaespiralis, which might hamper effective downregulation of genes with a low basal expression level. Here, we report an enhanced system that allows more effective control of genes expressed at low level. To this end, we subjected Pptr to targeted mutagenesis and produced 16 different promoters with different strength. Three of them, weaker than the wild-type promoter, were selected and characterized showing that they can indeed improve the performances of TetR/Pip-OFF repressible system both in vitro and in vivo increasing its stringency. Finally, we used these promoters to construct a series of bacterial biosensors with different sensitivity to DprE1 inhibitors and developed a whole-cell screening assay to identify inhibitors of this enzyme.
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Affiliation(s)
- Francesca Boldrin
- Department of Molecular Medicine, University of Padova, 35121, Padova, Italy
| | - Giulia Degiacomi
- Department of Molecular Medicine, University of Padova, 35121, Padova, Italy
| | - Agnese Serafini
- Department of Molecular Medicine, University of Padova, 35121, Padova, Italy
| | - Gaëlle S Kolly
- Ecole Polytechnique Fédérale de Lausanne, Global Health Institute, Station 19, 1015, Lausanne, Switzerland
| | - Marcello Ventura
- Department of Molecular Medicine, University of Padova, 35121, Padova, Italy
| | - Claudia Sala
- Ecole Polytechnique Fédérale de Lausanne, Global Health Institute, Station 19, 1015, Lausanne, Switzerland
| | - Roberta Provvedi
- Department of Biology, University of Padova, 35121, Padova, Italy
| | - Giorgio Palù
- Department of Molecular Medicine, University of Padova, 35121, Padova, Italy
| | - Stewart T Cole
- Ecole Polytechnique Fédérale de Lausanne, Global Health Institute, Station 19, 1015, Lausanne, Switzerland
| | - Riccardo Manganelli
- Department of Molecular Medicine, University of Padova, 35121, Padova, Italy
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67
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Gupta VK, Kumar MM, Singh D, Bisht D, Sharma S. Drug targets in dormant Mycobacterium tuberculosis: can the conquest against tuberculosis become a reality? Infect Dis (Lond) 2017; 50:81-94. [DOI: 10.1080/23744235.2017.1377346] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Affiliation(s)
- Vivek Kumar Gupta
- Department of Biochemistry, National JALMA Institute for Leprosy and Other Mycobacterial Diseases (ICMR), Agra, India
| | - M. Madhan Kumar
- Department of Immunology, National JALMA Institute for Leprosy and Other Mycobacterial Diseases (ICMR), Agra, India
| | - Dharmendra Singh
- Department of Biochemistry, National JALMA Institute for Leprosy and Other Mycobacterial Diseases (ICMR), Agra, India
| | - Deepa Bisht
- Department of Biochemistry, National JALMA Institute for Leprosy and Other Mycobacterial Diseases (ICMR), Agra, India
| | - Shweta Sharma
- Department of Biochemistry, National JALMA Institute for Leprosy and Other Mycobacterial Diseases (ICMR), Agra, India
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68
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Mukherjee R, Chandra Pal A, Banerjee M. Enabling faster Go/No-Go decisions through secondary screens in anti-mycobacterial drug discovery. Tuberculosis (Edinb) 2017; 106:44-52. [PMID: 28802404 DOI: 10.1016/j.tube.2017.06.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2016] [Revised: 03/30/2017] [Accepted: 06/28/2017] [Indexed: 10/19/2022]
Abstract
Management of tuberculosis, already a global health emergency, is becoming increasingly challenging with extensive misuse of second line drugs and their inaccessibility to eighty percent of the eligible patients. Rising statistics of antimicrobial resistance underscores the need for a set of completely new and more effective class of compounds with novel mechanisms of action that can be administered in combination to replace and shorten the present intensive six months regimen. In this review, we stress on the importance and the successes of phenotypic screening for discovery of anti-mycobacterial compound and discuss the importance of performing secondary screens and counter screens to get early estimate on compound's potentials for a successful development. We also highlight the recent advances and the related caveats in the assays that have been developed and discuss new screening modalities that can be incorporated during hit-selection to gain a quick insight into the mechanism of action, thus enabling quicker decisions in a hit triage.
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Affiliation(s)
- Raju Mukherjee
- Division of Biology, Indian Institute of Science Education and Research, Karakambadi Road, Tirupati, 517507, India.
| | - Anup Chandra Pal
- Division of Biology, Indian Institute of Science Education and Research, Karakambadi Road, Tirupati, 517507, India
| | - Mousumi Banerjee
- Indian Institute of Technology, Tirupati, Renigunta Road, Tirupati, 517506, India
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69
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Design, synthesis, and evaluation of substituted nicotinamide adenine dinucleotide (NAD +) synthetase inhibitors as potential antitubercular agents. Bioorg Med Chem Lett 2017; 27:4426-4430. [PMID: 28827112 DOI: 10.1016/j.bmcl.2017.08.012] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Revised: 08/05/2017] [Accepted: 08/07/2017] [Indexed: 11/20/2022]
Abstract
Nicotinamide adenine dinucleotide (NAD+) synthetase catalyzes the last step in NAD+ biosynthesis. Depletion of NAD+ is bactericidal for both active and dormant Mycobacterium tuberculosis (Mtb). By inhibiting NAD+ synthetase (NadE) from Mtb, we expect to eliminate NAD+ production which will result in cell death in both growing and nonreplicating Mtb. NadE inhibitors have been investigated against various pathogens, but few have been tested against Mtb. Here, we report on the expansion of a series of urea-sulfonamides, previously reported by Brouillette et al. Guided by docking studies, substituents on a terminal phenyl ring were varied to understand the structure-activity-relationships of substituents on this position. Compounds were tested as inhibitors of both recombinant Mtb NadE and Mtb whole cells. While the parent compound displayed very weak inhibition against Mtb NadE (IC50=1000µM), we observed up to a 10-fold enhancement in potency after optimization. Replacement of the 3,4-dichloro group on the phenyl ring of the parent compound with 4-nitro yielded 4f, the most potent compound of the series with an IC50 value of 90µM against Mtb NadE. Our modeling results show that these urea-sulfonamides potentially bind to the intramolecular ammonia tunnel, which transports ammonia from the glutaminase domain to the active site of the enzyme. This hypothesis is supported by data showing that, even when treated with potent inhibitors, NadE catalysis is restored when treated with exogenous ammonia. Most of these compounds also inhibited Mtb cell growth with MIC values of 19-100µg/mL. These results improve our understanding of the SAR of the urea-sulfonamides, their mechanism of binding to the enzyme, and of Mtb NadE as a potential antitubercular drug target.
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70
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Botella L, Vaubourgeix J, Livny J, Schnappinger D. Depleting Mycobacterium tuberculosis of the transcription termination factor Rho causes pervasive transcription and rapid death. Nat Commun 2017; 8:14731. [PMID: 28348398 PMCID: PMC5379054 DOI: 10.1038/ncomms14731] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Accepted: 01/26/2017] [Indexed: 12/30/2022] Open
Abstract
Rifampicin, which inhibits bacterial RNA polymerase, provides one of the most effective treatments for tuberculosis. Inhibition of the transcription termination factor Rho is used to treat some bacterial infections, but its importance varies across bacteria. Here we show that Rho of Mycobacterium tuberculosis functions to both define the 3' ends of mRNAs and silence substantial fragments of the genome. Brief inactivation of Rho affects over 500 transcripts enriched for genes of foreign DNA elements and bacterial virulence factors. Prolonged inactivation of Rho causes extensive pervasive transcription, a genome-wide increase in antisense transcripts, and a rapid loss of viability of replicating and non-replicating M. tuberculosis in vitro and during acute and chronic infection in mice. Collectively, these data suggest that inhibition of Rho may provide an alternative strategy to treat tuberculosis with an efficacy similar to inhibition of RNA polymerase.
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Affiliation(s)
- Laure Botella
- Department of Microbiology and Immunology, Weill Cornell Medicine, 413E 69th Street, New York, New York 10021, USA
| | - Julien Vaubourgeix
- Department of Microbiology and Immunology, Weill Cornell Medicine, 413E 69th Street, New York, New York 10021, USA
| | - Jonathan Livny
- Broad Institute of MIT and Harvard, 415 Main Street, Cambridge, Massachusetts 02142, USA
| | - Dirk Schnappinger
- Department of Microbiology and Immunology, Weill Cornell Medicine, 413E 69th Street, New York, New York 10021, USA
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71
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Glyoxylate detoxification is an essential function of malate synthase required for carbon assimilation in Mycobacterium tuberculosis. Proc Natl Acad Sci U S A 2017; 114:E2225-E2232. [PMID: 28265055 DOI: 10.1073/pnas.1617655114] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The glyoxylate shunt is a metabolic pathway of bacteria, fungi, and plants used to assimilate even-chain fatty acids (FAs) and has been implicated in persistence of Mycobacterium tuberculosis (Mtb). Recent work, however, showed that the first enzyme of the glyoxylate shunt, isocitrate lyase (ICL), may mediate survival of Mtb during the acute and chronic phases of infection in mice through physiologic functions apart from fatty acid metabolism. Here, we report that malate synthase (MS), the second enzyme of the glyoxylate shunt, is essential for in vitro growth and survival of Mtb on even-chain fatty acids, in part, for a previously unrecognized activity: mitigating the toxicity of glyoxylate excess arising from metabolism of even-chain fatty acids. Metabolomic profiling revealed that MS-deficient Mtb cultured on fatty acids accumulated high levels of the ICL aldehyde endproduct, glyoxylate, and increased levels of acetyl phosphate, acetoacetyl coenzyme A (acetoacetyl-CoA), butyryl CoA, acetoacetate, and β-hydroxybutyrate. These changes were indicative of a glyoxylate-induced state of oxaloacetate deficiency, acetate overload, and ketoacidosis. Reduction of intrabacterial glyoxylate levels using a chemical inhibitor of ICL restored growth of MS-deficient Mtb, despite inhibiting entry of carbon into the glyoxylate shunt. In vivo depletion of MS resulted in sterilization of Mtb in both the acute and chronic phases of mouse infection. This work thus identifies glyoxylate detoxification as an essential physiologic function of Mtb malate synthase and advances its validation as a target for drug development.
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72
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Ruecker N, Jansen R, Trujillo C, Puckett S, Jayachandran P, Piroli GG, Frizzell N, Molina H, Rhee KY, Ehrt S. Fumarase Deficiency Causes Protein and Metabolite Succination and Intoxicates Mycobacterium tuberculosis. Cell Chem Biol 2017; 24:306-315. [PMID: 28219662 DOI: 10.1016/j.chembiol.2017.01.005] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2016] [Revised: 12/07/2016] [Accepted: 01/19/2017] [Indexed: 12/22/2022]
Abstract
Enzymes of central carbon metabolism are essential mediators of Mycobacterium tuberculosis (Mtb) physiology and pathogenicity, but are often perceived to lack sufficient species selectivity to be pursued as potential drug targets. Fumarase (Fum) is an enzyme of the canonical tricarboxylic acid cycle and is dispensable in many organisms. Transposon mutagenesis studies in Mtb, however, indicate that Fum is required for optimal growth. Here, we report the generation and characterization of a genetically engineered Mtb strain in which Fum expression is conditionally regulated. This revealed that Fum deficiency is bactericidal in vitro and during both the acute and chronic phases of mouse infection. This essentiality is linked to marked accumulations of fumarate resulting in protein and metabolite succination, a covalent modification of cysteine thiol residues. These results identify Mtb Fum as a potentially species-specific drug target whose inactivation may kill Mtb through a covalently irreversible form of metabolic toxicity.
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Affiliation(s)
- Nadine Ruecker
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY 10065, USA
| | - Robert Jansen
- Department of Medicine, Weill Cornell Medical College, New York, NY 10065, USA
| | - Carolina Trujillo
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY 10065, USA
| | - Susan Puckett
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY 10065, USA
| | - Pradeepa Jayachandran
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY 10065, USA
| | - Gerardo G Piroli
- Department of Pharmacology, Physiology & Neuroscience, School of Medicine, University of South Carolina, Columbia, SC 29209, USA
| | - Norma Frizzell
- Department of Pharmacology, Physiology & Neuroscience, School of Medicine, University of South Carolina, Columbia, SC 29209, USA
| | - Henrik Molina
- Proteomics Resource Center, Rockefeller University, New York, NY 10065, USA
| | - Kyu Y Rhee
- Department of Medicine, Weill Cornell Medical College, New York, NY 10065, USA
| | - Sabine Ehrt
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY 10065, USA.
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73
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Hartman TE, Wang Z, Jansen RS, Gardete S, Rhee KY. Metabolic Perspectives on Persistence. Microbiol Spectr 2017; 5:10.1128/microbiolspec.TBTB2-0026-2016. [PMID: 28155811 PMCID: PMC5302851 DOI: 10.1128/microbiolspec.tbtb2-0026-2016] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2016] [Indexed: 02/07/2023] Open
Abstract
Accumulating evidence has left little doubt about the importance of persistence or metabolism in the biology and chemotherapy of tuberculosis. However, knowledge of the intersection between these two factors has only recently begun to emerge. Here, we provide a focused review of metabolic characteristics associated with Mycobacterium tuberculosis persistence. We focus on metabolism because it is the biochemical foundation of all physiologic processes and a distinguishing hallmark of M. tuberculosis physiology and pathogenicity. In addition, it serves as the chemical interface between host and pathogen. Existing knowledge, however, derives largely from physiologic contexts in which replication is the primary biochemical objective. The goal of this review is to reframe current knowledge of M. tuberculosis metabolism in the context of persistence, where quiescence is often a key distinguishing characteristic. Such a perspective may help ongoing efforts to develop more efficient cures and inform on novel strategies to break the cycle of transmission sustaining the pandemic.
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Affiliation(s)
- Travis E. Hartman
- Department of Medicine, Division of Infectious Diseases, Weill Cornell Medical College, New York, NY 10065
| | - Zhe Wang
- Department of Medicine, Division of Infectious Diseases, Weill Cornell Medical College, New York, NY 10065
| | - Robert S. Jansen
- Department of Medicine, Division of Infectious Diseases, Weill Cornell Medical College, New York, NY 10065
| | - Susana Gardete
- Department of Medicine, Division of Infectious Diseases, Weill Cornell Medical College, New York, NY 10065
| | - Kyu Y. Rhee
- Department of Medicine, Division of Infectious Diseases, Weill Cornell Medical College, New York, NY 10065
- Department of Microbiology & Immunology, Division of Infectious Diseases, Weill Cornell Medical College, New York, NY 10065
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74
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Gold B, Nathan C. Targeting Phenotypically Tolerant Mycobacterium tuberculosis. Microbiol Spectr 2017; 5:10.1128/microbiolspec.TBTB2-0031-2016. [PMID: 28233509 PMCID: PMC5367488 DOI: 10.1128/microbiolspec.tbtb2-0031-2016] [Citation(s) in RCA: 80] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2016] [Indexed: 01/08/2023] Open
Abstract
While the immune system is credited with averting tuberculosis in billions of individuals exposed to Mycobacterium tuberculosis, the immune system is also culpable for tempering the ability of antibiotics to deliver swift and durable cure of disease. In individuals afflicted with tuberculosis, host immunity produces diverse microenvironmental niches that support suboptimal growth, or complete growth arrest, of M. tuberculosis. The physiological state of nonreplication in bacteria is associated with phenotypic drug tolerance. Many of these host microenvironments, when modeled in vitro by carbon starvation, complete nutrient starvation, stationary phase, acidic pH, reactive nitrogen intermediates, hypoxia, biofilms, and withholding streptomycin from the streptomycin-addicted strain SS18b, render M. tuberculosis profoundly tolerant to many of the antibiotics that are given to tuberculosis patients in clinical settings. Targeting nonreplicating persisters is anticipated to reduce the duration of antibiotic treatment and rate of posttreatment relapse. Some promising drugs to treat tuberculosis, such as rifampin and bedaquiline, only kill nonreplicating M. tuberculosisin vitro at concentrations far greater than their minimal inhibitory concentrations against replicating bacilli. There is an urgent demand to identify which of the currently used antibiotics, and which of the molecules in academic and corporate screening collections, have potent bactericidal action on nonreplicating M. tuberculosis. With this goal, we review methods of high-throughput screening to target nonreplicating M. tuberculosis and methods to progress candidate molecules. A classification based on structures and putative targets of molecules that have been reported to kill nonreplicating M. tuberculosis revealed a rich diversity in pharmacophores.
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Affiliation(s)
- Ben Gold
- Department of Microbiology & Immunology, Weill Cornell Medical College, New York, NY, 10065
| | - Carl Nathan
- Department of Microbiology & Immunology, Weill Cornell Medical College, New York, NY, 10065
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Korte J, Alber M, Trujillo CM, Syson K, Koliwer-Brandl H, Deenen R, Köhrer K, DeJesus MA, Hartman T, Jacobs WR, Bornemann S, Ioerger TR, Ehrt S, Kalscheuer R. Trehalose-6-Phosphate-Mediated Toxicity Determines Essentiality of OtsB2 in Mycobacterium tuberculosis In Vitro and in Mice. PLoS Pathog 2016; 12:e1006043. [PMID: 27936238 PMCID: PMC5148154 DOI: 10.1371/journal.ppat.1006043] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Accepted: 11/04/2016] [Indexed: 01/13/2023] Open
Abstract
Trehalose biosynthesis is considered an attractive target for the development of antimicrobials against fungal, helminthic and bacterial pathogens including Mycobacterium tuberculosis. The most common biosynthetic route involves trehalose-6-phosphate (T6P) synthase OtsA and T6P phosphatase OtsB that generate trehalose from ADP/UDP-glucose and glucose-6-phosphate. In order to assess the drug target potential of T6P phosphatase, we generated a conditional mutant of M. tuberculosis allowing the regulated gene silencing of the T6P phosphatase gene otsB2. We found that otsB2 is essential for growth of M. tuberculosis in vitro as well as for the acute infection phase in mice following aerosol infection. By contrast, otsB2 is not essential for the chronic infection phase in mice, highlighting the substantial remodelling of trehalose metabolism during infection by M. tuberculosis. Blocking OtsB2 resulted in the accumulation of its substrate T6P, which appears to be toxic, leading to the self-poisoning of cells. Accordingly, blocking T6P production in a ΔotsA mutant abrogated otsB2 essentiality. T6P accumulation elicited a global upregulation of more than 800 genes, which might result from an increase in RNA stability implied by the enhanced neutralization of toxins exhibiting ribonuclease activity. Surprisingly, overlap with the stress response caused by the accumulation of another toxic sugar phosphate molecule, maltose-1-phosphate, was minimal. A genome-wide screen for synthetic lethal interactions with otsA identified numerous genes, revealing additional potential drug targets synergistic with OtsB2 suitable for combination therapies that would minimize the emergence of resistance to OtsB2 inhibitors. Trehalose biosynthesis is considered an attractive target for the development of new drugs against various microbial pathogens including Mycobacterium tuberculosis. In this human pathogen, two partially redundant pathways mediate trehalose biosynthesis. The OtsA-OtsB2 pathway, which dominates in culture, involves trehalose-6-phosphate (T6P) synthase OtsA and T6P phosphatase OtsB2. While OtsA is dispensable, OtsB2 is strictly essential for growth of M. tuberculosis. Using conditional gene silencing, we here show that essentiality of OtsB2 is linked to accumulation of its substrate T6P, which exhibits direct or indirect toxic effects. Regulated gene expression in vivo revealed that OtsB2 is required to establish an acute infection of M. tuberculosis in a mouse infection model, but is surprisingly fully dispensable during the chronic infection phase. This highlights that trehalose metabolism of M. tuberculosis is substantially remodelled during infection.
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Affiliation(s)
- Jan Korte
- Institute for Pharmaceutical Biology and Biotechnology, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
- Institute for Medical Microbiology and Hospital Hygiene, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
| | - Marina Alber
- Institute for Medical Microbiology and Hospital Hygiene, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
| | - Carolina M. Trujillo
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, New York, United States of America
| | - Karl Syson
- Department of Biological Chemistry, John Innes Centre, Norwich Research Park, Norwich, Norfolk, United Kingdom
| | - Hendrik Koliwer-Brandl
- Institute for Medical Microbiology and Hospital Hygiene, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
| | - René Deenen
- Biological and Medical Research Center (BMFZ), Cluster of Excellence on Plant Sciences (CEPLAS), Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
| | - Karl Köhrer
- Biological and Medical Research Center (BMFZ), Cluster of Excellence on Plant Sciences (CEPLAS), Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
| | - Michael A. DeJesus
- Department of Computer Science, Texas A&M University, College Station, Texas, United States of America
| | - Travis Hartman
- Department of Microbiology and Immunology, Howard Hughes Medical Institute, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - William R. Jacobs
- Department of Microbiology and Immunology, Howard Hughes Medical Institute, Albert Einstein College of Medicine, Bronx, New York, United States of America
| | - Stephen Bornemann
- Department of Biological Chemistry, John Innes Centre, Norwich Research Park, Norwich, Norfolk, United Kingdom
| | - Thomas R. Ioerger
- Department of Computer Science, Texas A&M University, College Station, Texas, United States of America
| | - Sabine Ehrt
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, New York, United States of America
| | - Rainer Kalscheuer
- Institute for Pharmaceutical Biology and Biotechnology, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
- Institute for Medical Microbiology and Hospital Hygiene, Heinrich-Heine-University Düsseldorf, Düsseldorf, Germany
- * E-mail:
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Evans JC, Trujillo C, Wang Z, Eoh H, Ehrt S, Schnappinger D, Boshoff HIM, Rhee KY, Barry CE, Mizrahi V. Validation of CoaBC as a Bactericidal Target in the Coenzyme A Pathway of Mycobacterium tuberculosis. ACS Infect Dis 2016; 2:958-968. [PMID: 27676316 PMCID: PMC5153693 DOI: 10.1021/acsinfecdis.6b00150] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
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Mycobacterium tuberculosis relies on its own ability to biosynthesize coenzyme A to meet the
needs of the myriad enzymatic reactions that depend on this cofactor
for activity. As such, the essential pantothenate and coenzyme A biosynthesis
pathways have attracted attention as targets for tuberculosis drug
development. To identify the optimal step for coenzyme A pathway disruption
in M. tuberculosis, we constructed
and characterized a panel of conditional knockdown mutants in coenzyme
A pathway genes. Here, we report that silencing of coaBC was bactericidal in vitro, whereas silencing of panB, panC, or coaE was bacteriostatic
over the same time course. Silencing of coaBC was
likewise bactericidal in vivo, whether initiated at infection or during
either the acute or chronic stages of infection, confirming that CoaBC
is required for M. tuberculosis to grow and persist in mice and arguing against significant CoaBC
bypass via transport and assimilation of host-derived pantetheine
in this animal model. These results provide convincing genetic validation
of CoaBC as a new bactericidal drug target.
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Affiliation(s)
- Joanna C. Evans
- MRC/NHLS/UCT Molecular Mycobacteriology Research Unit & DST/NRF Centre of Excellence for Biomedical TB Research, Institute of Infectious Disease and Molecular Medicine and Department of Pathology, Faculty of Health Sciences, University of Cape Town, Anzio Road, Observatory 7925, South Africa
| | - Carolina Trujillo
- Department of Microbiology
and Immunology, Weill Cornell Medical College, New York, New York 10065, United States
| | - Zhe Wang
- Department of Microbiology
and Immunology, Weill Cornell Medical College, New York, New York 10065, United States
- Division of Infectious Diseases, Department of Medicine, Weill Cornell Medical College, New York, New York 10065, United States
| | - Hyungjin Eoh
- Department of Microbiology
and Immunology, Weill Cornell Medical College, New York, New York 10065, United States
- Division of Infectious Diseases, Department of Medicine, Weill Cornell Medical College, New York, New York 10065, United States
| | - Sabine Ehrt
- Department of Microbiology
and Immunology, Weill Cornell Medical College, New York, New York 10065, United States
| | - Dirk Schnappinger
- Department of Microbiology
and Immunology, Weill Cornell Medical College, New York, New York 10065, United States
| | - Helena I. M. Boshoff
- Tuberculosis
Research Section, Laboratory of Clinical Infectious Diseases, National
Institute of Allergy and Infectious Disease, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Kyu Y. Rhee
- Department of Microbiology
and Immunology, Weill Cornell Medical College, New York, New York 10065, United States
- Division of Infectious Diseases, Department of Medicine, Weill Cornell Medical College, New York, New York 10065, United States
| | - Clifton E. Barry
- MRC/NHLS/UCT Molecular Mycobacteriology Research Unit & DST/NRF Centre of Excellence for Biomedical TB Research, Institute of Infectious Disease and Molecular Medicine and Department of Pathology, Faculty of Health Sciences, University of Cape Town, Anzio Road, Observatory 7925, South Africa
- Tuberculosis
Research Section, Laboratory of Clinical Infectious Diseases, National
Institute of Allergy and Infectious Disease, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Valerie Mizrahi
- MRC/NHLS/UCT Molecular Mycobacteriology Research Unit & DST/NRF Centre of Excellence for Biomedical TB Research, Institute of Infectious Disease and Molecular Medicine and Department of Pathology, Faculty of Health Sciences, University of Cape Town, Anzio Road, Observatory 7925, South Africa
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77
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Therapeutic Potential of the Mycobacterium tuberculosis Mycolic Acid Transporter, MmpL3. Antimicrob Agents Chemother 2016; 60:5198-207. [PMID: 27297488 DOI: 10.1128/aac.00826-16] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Accepted: 06/08/2016] [Indexed: 11/20/2022] Open
Abstract
In recent years, whole-cell-based screens for novel small molecule inhibitors active against Mycobacterium tuberculosis in culture followed by the whole-genome sequencing of spontaneous resistant mutants have identified multiple chemical scaffolds thought to kill the bacterium through the inactivation of the mycolic acid transporter, MmpL3. Consistent with the fact that MmpL3 is required for the formation of the mycobacterial outer membrane, we have conclusively shown in this study, using conditionally regulated knockdown mutants, that mmpL3 is required for the replication and viability of M. tuberculosis, both under standard laboratory growth conditions and during the acute and chronic phases of infection in mice. Speaking for the vulnerability of this target, silencing mmpL3 had a rapid bactericidal effect on actively replicating cells in vitro and reduced by 3 to 5 logs in less than 4 weeks the bacterial loads of acutely and chronically infected mouse lungs, respectively. Depletion of MmpL3 further rendered M. tuberculosis hypersusceptible to MmpL3 inhibitors. The exquisite vulnerability of MmpL3 at all stages of the infection establishes this transporter as an attractive new target with the potential to improve and shorten current drug-susceptible and drug-resistant tuberculosis chemotherapies.
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78
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Singh AK, Carette X, Potluri LP, Sharp JD, Xu R, Prisic S, Husson RN. Investigating essential gene function in Mycobacterium tuberculosis using an efficient CRISPR interference system. Nucleic Acids Res 2016; 44:e143. [PMID: 27407107 PMCID: PMC5062980 DOI: 10.1093/nar/gkw625] [Citation(s) in RCA: 101] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Accepted: 07/02/2016] [Indexed: 12/23/2022] Open
Abstract
Despite many methodological advances that have facilitated investigation of Mycobacterium tuberculosis pathogenesis, analysis of essential gene function in this slow-growing pathogen remains difficult. Here, we describe an optimized CRISPR-based method to inhibit expression of essential genes based on the inducible expression of an enzymatically inactive Cas9 protein together with gene-specific guide RNAs (CRISPR interference). Using this system to target several essential genes of M. tuberculosis, we achieved marked inhibition of gene expression resulting in growth inhibition, changes in susceptibility to small molecule inhibitors and disruption of normal cell morphology. Analysis of expression of genes containing sequences similar to those targeted by individual guide RNAs did not reveal significant off-target effects. Advantages of this approach include the ability to compare inhibited gene expression to native levels of expression, lack of the need to alter the M. tuberculosis chromosome, the potential to titrate the extent of transcription inhibition, and the ability to avoid off-target effects. Based on the consistent inhibition of transcription and the simple cloning strategy described in this work, CRISPR interference provides an efficient approach to investigate essential gene function that may be particularly useful in characterizing genes of unknown function and potential targets for novel small molecule inhibitors.
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Affiliation(s)
- Atul K Singh
- Division of Infectious Diseases, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Xavier Carette
- Division of Infectious Diseases, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Lakshmi-Prasad Potluri
- Division of Infectious Diseases, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Jared D Sharp
- Division of Infectious Diseases, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Ranfei Xu
- Division of Infectious Diseases, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Sladjana Prisic
- Division of Infectious Diseases, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
| | - Robert N Husson
- Division of Infectious Diseases, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA
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79
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Lin K, O'Brien KM, Trujillo C, Wang R, Wallach JB, Schnappinger D, Ehrt S. Mycobacterium tuberculosis Thioredoxin Reductase Is Essential for Thiol Redox Homeostasis but Plays a Minor Role in Antioxidant Defense. PLoS Pathog 2016; 12:e1005675. [PMID: 27249779 PMCID: PMC4889078 DOI: 10.1371/journal.ppat.1005675] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Accepted: 05/12/2016] [Indexed: 02/06/2023] Open
Abstract
Mycobacterium tuberculosis (Mtb) must cope with exogenous oxidative stress imposed by the host. Unlike other antioxidant enzymes, Mtb's thioredoxin reductase TrxB2 has been predicted to be essential not only to fight host defenses but also for in vitro growth. However, the specific physiological role of TrxB2 and its importance for Mtb pathogenesis remain undefined. Here we show that genetic inactivation of thioredoxin reductase perturbed several growth-essential processes, including sulfur and DNA metabolism and rapidly killed and lysed Mtb. Death was due to cidal thiol-specific oxidizing stress and prevented by a disulfide reductant. In contrast, thioredoxin reductase deficiency did not significantly increase susceptibility to oxidative and nitrosative stress. In vivo targeting TrxB2 eradicated Mtb during both acute and chronic phases of mouse infection. Deliberately leaky knockdown mutants identified the specificity of TrxB2 inhibitors and showed that partial inactivation of TrxB2 increased Mtb's susceptibility to rifampicin. These studies reveal TrxB2 as essential thiol-reducing enzyme in Mtb in vitro and during infection, establish the value of targeting TrxB2, and provide tools to accelerate the development of TrxB2 inhibitors.
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Affiliation(s)
- Kan Lin
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, New York, United States of America
- Program in Immunology and Microbial Pathogenesis, Weill Graduate School of Medical Sciences of Cornell University, New York, New York, United States of America
| | - Kathryn M. O'Brien
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, New York, United States of America
| | - Carolina Trujillo
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, New York, United States of America
| | - Ruojun Wang
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, New York, United States of America
- Program in Immunology and Microbial Pathogenesis, Weill Graduate School of Medical Sciences of Cornell University, New York, New York, United States of America
| | - Joshua B. Wallach
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, New York, United States of America
| | - Dirk Schnappinger
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, New York, United States of America
- * E-mail: (DS); (SE)
| | - Sabine Ehrt
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, New York, United States of America
- Program in Immunology and Microbial Pathogenesis, Weill Graduate School of Medical Sciences of Cornell University, New York, New York, United States of America
- * E-mail: (DS); (SE)
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80
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Choudhary E, Lunge A, Agarwal N. Strategies of genome editing in mycobacteria: Achievements and challenges. Tuberculosis (Edinb) 2016; 98:132-8. [PMID: 27156629 DOI: 10.1016/j.tube.2016.03.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Revised: 03/14/2016] [Accepted: 03/21/2016] [Indexed: 01/07/2023]
Abstract
Tremendous amount of physiological and functional complexities acquired through decades of evolutionary pressure makes Mycobacterium tuberculosis (Mtb) one of the most dreadful microorganisms infecting humans from centuries. Astonishing advances in genomics and genome editing tools substantially grew our knowledge about Mtb as an organism but dramatically failed to completely understand it as a pathogen. Though conventional tools based on homologous recombination, antisense, controlled proteolysis, etc. have made important contributions in advancing our understanding of the pathophysiology of Mtb, yet these approaches have not accentuated our exploration of mycobacterium on account of certain technical limitations. In this review article we have compiled various approaches implemented in genome editing of mycobacteria along with the latest adaptation of clustered regularly interspaced short palindromic repeat (CRISPR)-interference (CRISPRi), emphasizing the achievements and challenges associated with these techniques.
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Affiliation(s)
- Eira Choudhary
- Translational Health Science and Technology Institute, NCR Biotech Science Cluster, 3rd Milestone, Faridabad-Gurgaon Expressway, Faridabad 121001, Haryana, India; Symbiosis School of Biomedical Sciences, Symbiosis International University, Lavale, Pune 412115, Maharashtra, India
| | - Ajitesh Lunge
- Translational Health Science and Technology Institute, NCR Biotech Science Cluster, 3rd Milestone, Faridabad-Gurgaon Expressway, Faridabad 121001, Haryana, India; Jawaharlal Nehru University, New Mehrauli Road, Near Munirka, New Delhi 110067, Delhi, India
| | - Nisheeth Agarwal
- Translational Health Science and Technology Institute, NCR Biotech Science Cluster, 3rd Milestone, Faridabad-Gurgaon Expressway, Faridabad 121001, Haryana, India.
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81
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Cloning, expression and characterization of histidine-tagged biotin synthase of Mycobacterium tuberculosis. Tuberculosis (Edinb) 2016; 98:42-9. [PMID: 27156617 DOI: 10.1016/j.tube.2016.02.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Revised: 02/21/2016] [Accepted: 02/29/2016] [Indexed: 11/20/2022]
Abstract
The emergence of Mycobacterium tuberculosis strains that are resistant to the current anti-tuberculosis (TB) drugs necessitates a need to develop a new class of drugs whose targets are different from the current ones. M. tuberculosis biotin synthase (MtbBS) is one such target that is essential for the survival of the bacteria. In this study, MtbBS was cloned, overexpressed and purified to homogeneity for biochemical characterization. It is likely to be a dimer in its native form. Its pH and temperature optima are 8.0 and 37 °C, respectively. Km for DTB and SAM was 2.81 ± 0.35 and 9.95 ± 0.98 μM, respectively. The enzyme had a maximum velocity of 0.575 ± 0.015 μM min(-1), and a turn-over of 0.0935 min(-1). 5'-deoxyadenosine (dAH), S-(5'-Adenosyl)-l-cysteine (AdoCy) and S-(5'-Adenosyl)-l-homocysteine (AdoHcy) were competitive inhibitors of MtbBS with the following inactivation parameters: Ki = 24.2 μM, IC50 = 267.4 μM; Ki = 0.84 μM, IC50 = 9.28 μM; and Ki = 0.592 μM, IC50 = 6.54 μM for dAH, AdoCy and AdoHcy respectively. dAH could inhibit the growth of M. tuberculosis H37Ra with an MIC of 392.6 μg/ml. This information should be useful for the discovery of inhibitors of MtbBS.
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82
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References. Antibiotics (Basel) 2015. [DOI: 10.1128/9781555819316.refs] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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83
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Ehrt S, Rhee K, Schnappinger D. Mycobacterial genes essential for the pathogen's survival in the host. Immunol Rev 2015; 264:319-26. [PMID: 25703569 DOI: 10.1111/imr.12256] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Mycobacterium tuberculosis (Mtb) has evolved within the human immune system as both host and reservoir. The study of genes required for its growth and persistence in vivo thus offers linked insights into its pathogenicity and host immunity. Studies of Mtb mutants have implicated metabolic adaptation (consisting of carbon, nitrogen, vitamin, and cofactor metabolism), intrabacterial pH homeostasis, and defense against reactive oxygen and reactive nitrogen species, as key determinants of its pathogenicity. However, the mechanisms of host immunity are complex and often combinatorial. Growing evidence has thus begun to reveal that the determinants of Mtb's pathogenicity may serve a broader and more complex array of functions than the isolated experimental settings in which they were initially found. Here, we review select examples, which exemplify this complexity, highlighting the distinct phases of Mtb's life cycle and the diverse microenvironments encountered therein.
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Affiliation(s)
- Sabine Ehrt
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, NY, USA
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84
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Karp CL, Wilson CB, Stuart LM. Tuberculosis vaccines: barriers and prospects on the quest for a transformative tool. Immunol Rev 2015; 264:363-81. [PMID: 25703572 PMCID: PMC4368410 DOI: 10.1111/imr.12270] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The road to a more efficacious vaccine that could be a truly transformative tool for decreasing tuberculosis morbidity and mortality, along with Mycobacterium tuberculosis transmission, is quite daunting. Despite this, there are reasons for optimism. Abetted by better conceptual clarity, clear acknowledgment of the degree of our current immunobiological ignorance, the availability of powerful new tools for dissecting the immunopathogenesis of human tuberculosis, the generation of more creative diversity in tuberculosis vaccine concepts, the development of better fit-for-purpose animal models, and the potential of more pragmatic approaches to the clinical testing of vaccine candidates, the field has promise for delivering novel tools for dealing with this worldwide scourge of poverty.
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Affiliation(s)
- Christopher L Karp
- Discovery and Translational Sciences, Global Health, The Bill & Melinda Gates Foundation, Seattle, WA, USA
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85
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Baer CE, Rubin EJ, Sassetti CM. New insights into TB physiology suggest untapped therapeutic opportunities. Immunol Rev 2015; 264:327-43. [PMID: 25703570 DOI: 10.1111/imr.12267] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The current regimens used to treat tuberculosis are largely comprised of serendipitously discovered drugs that are combined based on clinical experience. Despite curing millions, these drug regimens are limited by the long course of therapy, the emergence of resistance, and the persistent tissue damage that remains after treatment. The last two decades have produced only a single new drug but have represented a renaissance in our understanding of the physiology of tuberculosis infection. The advent of mycobacterial genetics, sophisticated immunological methods, and imaging technologies have transformed our understanding of bacterial physiology as well as the contribution of the host response to disease outcome. Specific alterations in bacterial metabolism, heterogeneity in bacterial state, and drug penetration all limit the effectiveness of antimicrobial therapy. This review summarizes these new biological insights and discusses strategies to exploit them for the rational development of more effective therapeutics. Three general strategies are discussed. First, our emerging insight into bacterial physiology suggests new pathways that might be targeted to accelerate therapy. Second, we explore whether the concept of genetic synergy can be used to design effective combination therapies. Finally, we outline possible approaches to modulate the host response to accentuate antibiotic efficacy. These biology-driven strategies promise to produce more effective therapies.
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Affiliation(s)
- Christina E Baer
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, MA, USA; Howard Hughes Medical Institute, Chevy Chase, MD, USA
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86
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87
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Phenotypic Heterogeneity, a Phenomenon That May Explain Why Quorum Sensing Does Not Always Result in Truly Homogenous Cell Behavior. Appl Environ Microbiol 2015. [PMID: 26025903 DOI: 10.1128/aem.00900-15/format/epub] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/08/2023] Open
Abstract
Phenotypic heterogeneity describes the occurrence of "nonconformist" cells within an isogenic population. The nonconformists show an expression profile partially different from that of the remainder of the population. Phenotypic heterogeneity affects many aspects of the different bacterial lifestyles, and it is assumed that it increases bacterial fitness and the chances for survival of the whole population or smaller subpopulations in unfavorable environments. Well-known examples for phenotypic heterogeneity have been associated with antibiotic resistance and frequently occurring persister cells. Other examples include heterogeneous behavior within biofilms, DNA uptake and bacterial competence, motility (i.e., the synthesis of additional flagella), onset of spore formation, lysis of phages within a small subpopulation, and others. Interestingly, phenotypic heterogeneity was recently also observed with respect to quorum-sensing (QS)-dependent processes, and the expression of autoinducer (AI) synthase genes and other QS-dependent genes was found to be highly heterogeneous at a single-cell level. This phenomenon was observed in several Gram-negative bacteria affiliated with the genera Vibrio, Dinoroseobacter, Pseudomonas, Sinorhizobium, and Mesorhizobium. A similar observation was made for the Gram-positive bacterium Listeria monocytogenes. Since AI molecules have historically been thought to be the keys to homogeneous behavior within isogenic populations, the observation of heterogeneous expression is quite intriguing and adds a new level of complexity to the QS-dependent regulatory networks. All together, the many examples of phenotypic heterogeneity imply that we may have to partially revise the concept of homogeneous and coordinated gene expression in isogenic bacterial populations.
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88
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Evans JC, Mizrahi V. The application of tetracyclineregulated gene expression systems in the validation of novel drug targets in Mycobacterium tuberculosis. Front Microbiol 2015; 6:812. [PMID: 26300875 PMCID: PMC4523840 DOI: 10.3389/fmicb.2015.00812] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Accepted: 07/23/2015] [Indexed: 12/12/2022] Open
Abstract
Although efforts to identify novel therapies for the treatment of tuberculosis have led to the identification of several promising drug candidates, the identification of high-quality hits from conventional whole-cell screens remains disappointingly low. The elucidation of the genome sequence of Mycobacterium tuberculosis (Mtb) facilitated a shift to target-based approaches to drug design but these efforts have proven largely unsuccessful. More recently, regulated gene expression systems that enable dose-dependent modulation of gene expression have been applied in target validation to evaluate the requirement of individual genes for the growth of Mtb both in vitro and in vivo. Notably, these systems can also provide a measure of the extent to which putative targets must be depleted in order to manifest a growth inhibitory phenotype. Additionally, the successful implementation of Mtb strains engineered to under-express specific molecular targets in whole-cell screens has enabled the simultaneous identification of cell-permeant inhibitors with defined mechanisms of action. Here, we review the application of tetracycline-regulated gene expression systems in the validation of novel drug targets in Mtb, highlighting both the strengths and limitations associated with this approach to target validation.
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Affiliation(s)
- Joanna C. Evans
- South African Medical Research Council/National Health Laboratory Service/University of Cape Town Molecular Mycobacteriology Research UnitCape Town, South Africa
- DST/NRF Centre of Excellence for Biomedical TB Research, Institute of Infectious Disease and Molecular Medicine and Division of Medical Microbiology, Faculty of Health Sciences, University of Cape TownCape Town, South Africa
| | - Valerie Mizrahi
- South African Medical Research Council/National Health Laboratory Service/University of Cape Town Molecular Mycobacteriology Research UnitCape Town, South Africa
- DST/NRF Centre of Excellence for Biomedical TB Research, Institute of Infectious Disease and Molecular Medicine and Division of Medical Microbiology, Faculty of Health Sciences, University of Cape TownCape Town, South Africa
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89
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Phenotypic Heterogeneity, a Phenomenon That May Explain Why Quorum Sensing Does Not Always Result in Truly Homogenous Cell Behavior. Appl Environ Microbiol 2015; 81:5280-9. [PMID: 26025903 DOI: 10.1128/aem.00900-15] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Phenotypic heterogeneity describes the occurrence of "nonconformist" cells within an isogenic population. The nonconformists show an expression profile partially different from that of the remainder of the population. Phenotypic heterogeneity affects many aspects of the different bacterial lifestyles, and it is assumed that it increases bacterial fitness and the chances for survival of the whole population or smaller subpopulations in unfavorable environments. Well-known examples for phenotypic heterogeneity have been associated with antibiotic resistance and frequently occurring persister cells. Other examples include heterogeneous behavior within biofilms, DNA uptake and bacterial competence, motility (i.e., the synthesis of additional flagella), onset of spore formation, lysis of phages within a small subpopulation, and others. Interestingly, phenotypic heterogeneity was recently also observed with respect to quorum-sensing (QS)-dependent processes, and the expression of autoinducer (AI) synthase genes and other QS-dependent genes was found to be highly heterogeneous at a single-cell level. This phenomenon was observed in several Gram-negative bacteria affiliated with the genera Vibrio, Dinoroseobacter, Pseudomonas, Sinorhizobium, and Mesorhizobium. A similar observation was made for the Gram-positive bacterium Listeria monocytogenes. Since AI molecules have historically been thought to be the keys to homogeneous behavior within isogenic populations, the observation of heterogeneous expression is quite intriguing and adds a new level of complexity to the QS-dependent regulatory networks. All together, the many examples of phenotypic heterogeneity imply that we may have to partially revise the concept of homogeneous and coordinated gene expression in isogenic bacterial populations.
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90
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Arbade GK, Srivastava SK. Cloning, expression, purification, crystallization and preliminary X-ray diffraction studies of NAD synthetase from methicillin-resistant Staphylococcus aureus. ACTA CRYSTALLOGRAPHICA SECTION F-STRUCTURAL BIOLOGY COMMUNICATIONS 2015; 71:763-9. [PMID: 26057809 DOI: 10.1107/s2053230x15007906] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Accepted: 04/21/2015] [Indexed: 11/10/2022]
Abstract
Staphylococcus aureus is an important human and animal pathogen that causes a wide range of infections. The prevalence of multidrug-resistant S. aureus strains in both hospital and community settings makes it imperative to characterize new drug targets to combat S. aureus infections. In this context, enzymes involved in NAD metabolism and synthesis are significant drug targets as NAD is a central player in several cellular processes. NAD synthetase catalyzes the last step in the biosynthesis of nicotinamide adenine dinucleotide, making it a crucial intermediate enzyme linked to the biosynthesis of several amino acids, purine and pyrimidine nucleotides, coenzymes and antibiotics.
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Affiliation(s)
- Gajanan Kashinathrao Arbade
- Department of Biosciences and Technology, Defence Institute of Advanced Technology, Pune, Maharashtra 411 025, India
| | - Sandeep Kumar Srivastava
- Department of Biosciences and Technology, Defence Institute of Advanced Technology, Pune, Maharashtra 411 025, India
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91
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Abstract
Very few chemically novel agents have been approved for antibacterial chemotherapies during the last 50 yr. Yet new antibacterial drugs are needed to reduce the impact on global health of an increasing number of drug-resistant infections, including highly drug-resistant forms of tuberculosis. This review discusses how genetic approaches can be used to study the mechanism of action of whole-cell screening hits and facilitate target-driven strategies for antimicrobial drug development.
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Affiliation(s)
- Dirk Schnappinger
- Department of Microbiology and Immunology, Weill Cornell Medical College, New York, New York 10065
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92
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Rodionova IA, Zuccola HJ, Sorci L, Aleshin AE, Kazanov MD, Ma CT, Sergienko E, Rubin EJ, Locher CP, Osterman AL. Mycobacterial nicotinate mononucleotide adenylyltransferase: structure, mechanism, and implications for drug discovery. J Biol Chem 2015; 290:7693-706. [PMID: 25631047 DOI: 10.1074/jbc.m114.628016] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Nicotinate mononucleotide adenylyltransferase NadD is an essential enzyme in the biosynthesis of the NAD cofactor, which has been implicated as a target for developing new antimycobacterial therapies. Here we report the crystal structure of Mycobacterium tuberculosis NadD (MtNadD) at a resolution of 2.4 Å. A remarkable new feature of the MtNadD structure, compared with other members of this enzyme family, is a 310 helix that locks the active site in an over-closed conformation. As a result, MtNadD is rendered inactive as it is topologically incompatible with substrate binding and catalysis. Directed mutagenesis was also used to further dissect the structural elements that contribute to the interactions of the two MtNadD substrates, i.e. ATP and nicotinic acid mononucleotide (NaMN). For inhibitory profiling of partially active mutants and wild type MtNadD, we used a small molecule inhibitor of MtNadD with moderate affinity (Ki ∼ 25 μM) and antimycobacterial activity (MIC80) ∼ 40-80 μM). This analysis revealed interferences with some of the residues in the NaMN binding subsite consistent with the competitive inhibition observed for the NaMN substrate (but not ATP). A detailed steady-state kinetic analysis of MtNadD suggests that ATP must first bind to allow efficient NaMN binding and catalysis. This sequential mechanism is consistent with the requirement of transition to catalytically competent (open) conformation hypothesized from structural modeling. A possible physiological significance of this mechanism is to enable the down-regulation of NAD synthesis under ATP-limiting dormancy conditions. These findings point to a possible new strategy for designing inhibitors that lock the enzyme in the inactive over-closed conformation.
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Affiliation(s)
- Irina A Rodionova
- From the Sanford-Burnham Medical Research Institute, La Jolla, California 92037
| | - Harmon J Zuccola
- Vertex Pharmaceuticals Incorporated, Boston, Massachusetts 02210
| | - Leonardo Sorci
- Department of Clinical Sciences, Section of Biochemistry, Polytechnic University of Marche, Ancona 60131, Italy
| | - Alexander E Aleshin
- From the Sanford-Burnham Medical Research Institute, La Jolla, California 92037
| | - Marat D Kazanov
- A. A. Kharkevich Institute for Information Transmission Problems, Russian Academy of Sciences, 127051 Moscow, Russia, and
| | - Chen-Ting Ma
- From the Sanford-Burnham Medical Research Institute, La Jolla, California 92037
| | - Eduard Sergienko
- From the Sanford-Burnham Medical Research Institute, La Jolla, California 92037
| | - Eric J Rubin
- Department of Immunology and Infectious Diseases, Harvard School of Public Health, Boston, Massachusetts 02115
| | | | - Andrei L Osterman
- From the Sanford-Burnham Medical Research Institute, La Jolla, California 92037,
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93
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Abstract
By definition, essential genes are fundamental to bacterial growth, yet the functions of many such genes remain unknown. Essential genes furthermore are central to the activity of most antibacterial drugs and among the most attractive targets for the development of new therapeutics. This chapter describes how synthetic genetic switches that utilize transcriptional repression, controlled proteolysis, or both to silence gene activity can be applied to construct and characterize conditional knockdown (cKD) mutants for essential genes in Mycobacterium smegmatis and Mycobacterium tuberculosis.
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94
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Resuscitation-promoting factors are cell wall-lytic enzymes with important roles in the germination and growth of Streptomyces coelicolor. J Bacteriol 2014; 197:848-60. [PMID: 25512314 DOI: 10.1128/jb.02464-14] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Dormancy is a common strategy adopted by bacterial cells as a means of surviving adverse environmental conditions. For Streptomyces bacteria, this involves developing chains of dormant exospores that extend away from the colony surface. Both spore formation and subsequent spore germination are tightly controlled processes, and while significant progress has been made in understanding the underlying regulatory and enzymatic bases for these, there are still significant gaps in our understanding. One class of proteins with a potential role in spore-associated processes are the so-called resuscitation-promoting factors, or Rpfs, which in other actinobacteria are needed to restore active growth to dormant cell populations. The model species Streptomyces coelicolor encodes five Rpf proteins (RpfA to RfpE), and here we show that these proteins have overlapping functions during growth. Collectively, the S. coelicolor Rpfs promote spore germination and are critical for growth under nutrient-limiting conditions. Previous studies have revealed structural similarities between the Rpf domain and lysozyme, and our in vitro biochemical assays revealed various levels of peptidoglycan cleavage capabilities for each of these five Streptomyces enzymes. Peptidoglycan remodeling by enzymes such as these must be stringently governed so as to retain the structural integrity of the cell wall. Our results suggest that one of the Rpfs, RpfB, is subject to a unique mode of enzymatic autoregulation, mediated by a domain of previously unknown function (DUF348) located within the N terminus of the protein; removal of this domain led to significantly enhanced peptidoglycan cleavage.
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95
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Abstract
Metabolism underpins the physiology and pathogenesis of Mycobacterium tuberculosis. However, although experimental mycobacteriology has provided key insights into the metabolic pathways that are essential for survival and pathogenesis, determining the metabolic status of bacilli during different stages of infection and in different cellular compartments remains challenging. Recent advances-in particular, the development of systems biology tools such as metabolomics-have enabled key insights into the biochemical state of M. tuberculosis in experimental models of infection. In addition, their use to elucidate mechanisms of action of new and existing antituberculosis drugs is critical for the development of improved interventions to counter tuberculosis. This review provides a broad summary of mycobacterial metabolism, highlighting the adaptation of M. tuberculosis as specialist human pathogen, and discusses recent insights into the strategies used by the host and infecting bacillus to influence the outcomes of the host-pathogen interaction through modulation of metabolic functions.
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Affiliation(s)
- Digby F Warner
- Medical Research Council/National Health Laboratory Services/University of Cape Town Molecular Mycobacteriology Research Unit and Department of Science and Technology/National Research Foundation Centre of Excellence for Biomedical TB Research, Institute of Infectious Disease and Molecular Medicine and Division of Medical Microbiology, University of Cape Town, Rondebosch 7700, South Africa
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96
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Bashiri G, Baker EN. Production of recombinant proteins in Mycobacterium smegmatis for structural and functional studies. Protein Sci 2014; 24:1-10. [PMID: 25303009 DOI: 10.1002/pro.2584] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2014] [Revised: 10/07/2014] [Accepted: 10/08/2014] [Indexed: 11/11/2022]
Abstract
Protein production using recombinant DNA technology has a fundamental impact on our understanding of biology through providing proteins for structural and functional studies. Escherichia coli (E. coli) has been traditionally used as the default expression host to over-express and purify proteins from many different organisms. E. coli does, however, have known shortcomings for obtaining soluble, properly folded proteins suitable for downstream studies. These shortcomings are even more pronounced for the mycobacterial pathogen Mycobacterium tuberculosis, the bacterium that causes tuberculosis, with typically only one third of proteins expressed in E. coli produced as soluble proteins. Mycobacterium smegmatis (M. smegmatis) is a closely related and non-pathogenic species that has been successfully used as an expression host for production of proteins from various mycobacterial species. In this review, we describe the early attempts to produce mycobacterial proteins in alternative expression hosts and then focus on available expression systems in M. smegmatis. The advantages of using M. smegmatis as an expression host, its application in structural biology and some practical aspects of protein production are also discussed. M. smegmatis provides an effective expression platform for enhanced understanding of mycobacterial biology and pathogenesis and for developing novel and better therapeutics and diagnostics.
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Affiliation(s)
- Ghader Bashiri
- Structural Biology Laboratory, School of Biological Sciences and Maurice Wilkins Centre for Molecular Biodiscovery, The University of Auckland, Auckland, 1010, New Zealand
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97
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Targeting bacterial central metabolism for drug development. ACTA ACUST UNITED AC 2014; 21:1423-32. [PMID: 25442374 DOI: 10.1016/j.chembiol.2014.08.020] [Citation(s) in RCA: 110] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Revised: 06/25/2014] [Accepted: 08/08/2014] [Indexed: 11/23/2022]
Abstract
Current antibiotics, derived mainly from natural sources, inhibit a narrow spectrum of cellular processes, namely DNA replication, protein synthesis, and cell wall biosynthesis. With the worldwide explosion of drug resistance, there is renewed interest in the investigation of alternate essential cellular processes, including bacterial central metabolic pathways, as a drug target space for the next generation of antibiotics. However, the validation of targets in central metabolism is more complex, as essentiality of such targets can be conditional and/or contextual. Bearing in mind our enhanced understanding of prokaryotic central metabolism, a key question arises: can central metabolism be bacteria's Achilles' heel and a therapeutic target for the development of new classes of antibiotics? In this review, we draw lessons from oncology and attempt to address some of the open questions related to feasibility of targeting bacterial central metabolism as a strategy for developing new antibacterial drugs.
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98
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Zheng Y, Jiang X, Gao F, Song J, Sun J, Wang L, Sun X, Lu Z, Zhang H. Identification of plant-derived natural products as potential inhibitors of the Mycobacterium tuberculosis proteasome. BMC COMPLEMENTARY AND ALTERNATIVE MEDICINE 2014; 14:400. [PMID: 25315519 PMCID: PMC4203866 DOI: 10.1186/1472-6882-14-400] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/02/2014] [Accepted: 10/07/2014] [Indexed: 01/22/2023]
Abstract
Background The Mycobacterium tuberculosis (Mtb) proteasome has been established as a viable target for the development of anti-tuberculosis agents. In this study, the inhibitory activities of 100 plant-derived natural products on the Mtb proteasome were analyzed to identify novel potential inhibitors. Methods The fluorescent substrate Suc-Leu-Leu-Val-Tyr-AMC can be hydrolyzed by the proteasome to release free AMC, the fluorescence of which is proportional to the proteasome activity. The inhibitory activities of 100 natural products (each at a final concentration of 200 μM) were detected by this method using MG132 as a positive control. Results Twelve of these natural products (10 of which were flavonoids) inhibited the activity of the Mtb proteasome by more than 65%. Comparison of the structural differences between the flavonoids with good inhibitory activity and those without inhibitory activity revealed that the hydroxyl at the flavonoid C ring C-3 or the hydroxyl/methoxyl at the flavonoid A ring C-6 were critical for the inhibition of proteasomal activity. Conclusions These data indicate that flavonoids represent a basis for rational structural design in the process of novel anti-tuberculosis drug discovery.
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99
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Vashisht R, Bhat AG, Kushwaha S, Bhardwaj A, Consortium OSDD, Brahmachari SK. Systems level mapping of metabolic complexity in Mycobacterium tuberculosis to identify high-value drug targets. J Transl Med 2014; 12:263. [PMID: 25304862 PMCID: PMC4201925 DOI: 10.1186/s12967-014-0263-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Accepted: 09/11/2014] [Indexed: 01/17/2023] Open
Abstract
BACKGROUND The effectiveness of current therapeutic regimens for Mycobacterium tuberculosis (Mtb) is diminished by the need for prolonged therapy and the rise of drug resistant/tolerant strains. This global health threat, despite decades of basic research and a wealth of legacy knowledge, is due to a lack of systems level understanding that can innovate the process of fast acting and high efficacy drug discovery. METHODS The enhanced functional annotations of the Mtb genome, which were previously obtained through a crowd sourcing approach was used to reconstruct the metabolic network of Mtb in a bottom up manner. We represent this information by developing a novel Systems Biology Spindle Map of Metabolism (SBSM) and comprehend its static and dynamic structure using various computational approaches based on simulation and design. RESULTS The reconstructed metabolism of Mtb encompasses 961 metabolites, involved in 1152 reactions catalyzed by 890 protein coding genes, organized into 50 pathways. By accounting for static and dynamic analysis of SBSM in Mtb we identified various critical proteins required for the growth and survival of bacteria. Further, we assessed the potential of these proteins as putative drug targets that are fast acting and less toxic. Further, we formulate a novel concept of metabolic persister genes (MPGs) and compared our predictions with published in vitro and in vivo experimental evidence. Through such analyses, we report for the first time that de novo biosynthesis of NAD may give rise to bacterial persistence in Mtb under conditions of metabolic stress induced by conventional anti-tuberculosis therapy. We propose such MPG's as potential combination of drug targets for existing antibiotics that can improve their efficacy and efficiency for drug tolerant bacteria. CONCLUSION The systems level framework formulated by us to identify potential non-toxic drug targets and strategies to circumvent the issue of bacterial persistence can substantially aid in the process of TB drug discovery and translational research.
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Affiliation(s)
- Rohit Vashisht
- />CSIR-Open Source Drug Discovery Unit, New Delhi, India
- />Academy of Scientific and Innovative Research, New Delhi, India
| | - Ashwini G Bhat
- />CSIR-Open Source Drug Discovery Unit, New Delhi, India
| | | | - Anshu Bhardwaj
- />CSIR-Open Source Drug Discovery Unit, New Delhi, India
| | - OSDD Consortium
- />CSIR-Open Source Drug Discovery Unit, New Delhi, India
- />Academy of Scientific and Innovative Research, New Delhi, India
- />CSIR - Institute of Genomics and Integrative Biology, New Delhi, India
| | - Samir K Brahmachari
- />CSIR-Open Source Drug Discovery Unit, New Delhi, India
- />Academy of Scientific and Innovative Research, New Delhi, India
- />CSIR - Institute of Genomics and Integrative Biology, New Delhi, India
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100
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Subbian S, Eugenin E, Kaplan G. Detection of Mycobacterium tuberculosis in latently infected lungs by immunohistochemistry and confocal microscopy. J Med Microbiol 2014; 63:1432-1435. [PMID: 25161200 DOI: 10.1099/jmm.0.081091-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Detection of latent Mycobacterium tuberculosis is a challenge in the diagnosis of asymptomatic, subclinical tuberculosis. We report the development of an immunofluorescence technique to visualize and enumerate M. tuberculosis in latently infected rabbit lungs where no acid-fast-stained organisms were seen and no cultivable bacilli were obtained by the agar-plating method.
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Affiliation(s)
- Selvakumar Subbian
- Public Health Research Institute (PHRI), Rutgers Biomedical and Health Sciences, Rutgers University, Newark, NJ, USA.,Laboratory of Mycobacterial Immunity and Pathogenesis, Rutgers University, Newark, NJ, USA
| | - Eliseo Eugenin
- Public Health Research Institute (PHRI), Rutgers Biomedical and Health Sciences, Rutgers University, Newark, NJ, USA
| | - Gilla Kaplan
- The Bill & Melinda Gates Foundation, Seattle, WA, USA.,Public Health Research Institute (PHRI), Rutgers Biomedical and Health Sciences, Rutgers University, Newark, NJ, USA.,Laboratory of Mycobacterial Immunity and Pathogenesis, Rutgers University, Newark, NJ, USA
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