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Discovery of cofactor-specific, bactericidal Mycobacterium tuberculosis InhA inhibitors using DNA-encoded library technology. Proc Natl Acad Sci U S A 2016; 113:E7880-E7889. [PMID: 27864515 DOI: 10.1073/pnas.1610978113] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Millions of individuals are infected with and die from tuberculosis (TB) each year, and multidrug-resistant (MDR) strains of TB are increasingly prevalent. As such, there is an urgent need to identify novel drugs to treat TB infections. Current frontline therapies include the drug isoniazid, which inhibits the essential NADH-dependent enoyl-acyl-carrier protein (ACP) reductase, InhA. To inhibit InhA, isoniazid must be activated by the catalase-peroxidase KatG. Isoniazid resistance is linked primarily to mutations in the katG gene. Discovery of InhA inhibitors that do not require KatG activation is crucial to combat MDR TB. Multiple discovery efforts have been made against InhA in recent years. Until recently, despite achieving high potency against the enzyme, these efforts have been thwarted by lack of cellular activity. We describe here the use of DNA-encoded X-Chem (DEX) screening, combined with selection of appropriate physical properties, to identify multiple classes of InhA inhibitors with cell-based activity. The utilization of DEX screening allowed the interrogation of very large compound libraries (1011 unique small molecules) against multiple forms of the InhA enzyme in a multiplexed format. Comparison of the enriched library members across various screening conditions allowed the identification of cofactor-specific inhibitors of InhA that do not require activation by KatG, many of which had bactericidal activity in cell-based assays.
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Suliman S, Geldenhuys H, Johnson JL, Hughes JE, Smit E, Murphy M, Toefy A, Lerumo L, Hopley C, Pienaar B, Chheng P, Nemes E, Hoft DF, Hanekom WA, Boom WH, Hatherill M, Scriba TJ. Bacillus Calmette-Guérin (BCG) Revaccination of Adults with Latent Mycobacterium tuberculosis Infection Induces Long-Lived BCG-Reactive NK Cell Responses. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2016; 197:1100-1110. [PMID: 27412415 PMCID: PMC4976036 DOI: 10.4049/jimmunol.1501996] [Citation(s) in RCA: 100] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Accepted: 06/07/2016] [Indexed: 01/14/2023]
Abstract
One third of the global population is estimated to be latently infected with Mycobacterium tuberculosis We performed a phase I randomized controlled trial of isoniazid preventive therapy (IPT) before revaccination with bacillus Calmette-Guérin (BCG) in healthy, tuberculin skin test-positive (≥15-mm induration), HIV-negative South African adults. We hypothesized that preclearance of latent bacilli with IPT modulates BCG immunogenicity following revaccination. Frequencies and coexpression of IFN-γ, TNF-α, IL-2, IL-17, and/or IL-22 in CD4 T cells and IFN-γ-expressing CD8 T, γδ T, CD3(+)CD56(+) NKT-like, and NK cells in response to BCG were measured using whole blood intracellular cytokine staining and flow cytometry. We analyzed 72 participants who were revaccinated with BCG after IPT (n = 33) or without prior IPT (n = 39). IPT had little effect on frequencies or cytokine coexpression patterns of M. tuberculosis- or BCG-specific responses. Revaccination transiently boosted BCG-specific Th1 cytokine-expressing CD4, CD8, and γδ T cells. Despite high frequencies of IFN-γ-expressing BCG-reactive CD3(+)CD56(+) NKT-like cells and CD3(-)CD56(dim) and CD3(-)CD56(hi) NK cells at baseline, BCG revaccination boosted these responses, which remained elevated up to 1 y after revaccination. Such BCG-reactive memory NK cells were induced by BCG vaccination in infants, whereas in vitro IFN-γ expression by NK cells upon BCG stimulation was dependent on IL-12 and IL-18. Our data suggest that isoniazid preclearance of M. tuberculosis bacilli has little effect on the magnitude, persistence, or functional attributes of lymphocyte responses boosted by BCG revaccination. Our study highlights the surprising durability of BCG-boosted memory NKT-like and NK cells expressing antimycobacterial effector molecules, which may be novel targets for tuberculosis vaccines.
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Affiliation(s)
- Sara Suliman
- South African Tuberculosis Vaccine Initiative (SATVI), Institute of Infectious Disease and Molecular Medicine and Division of Immunology, Department of Pathology, University of Cape Town, Cape Town, South Africa
| | - Hennie Geldenhuys
- South African Tuberculosis Vaccine Initiative (SATVI), Institute of Infectious Disease and Molecular Medicine and Division of Immunology, Department of Pathology, University of Cape Town, Cape Town, South Africa
| | - John L. Johnson
- Tuberculosis Research Unit, Department of Medicine, Case Western Reserve University and University Hospitals Case Medical Center, Cleveland, OH, U.S.A
| | - Jane E. Hughes
- South African Tuberculosis Vaccine Initiative (SATVI), Institute of Infectious Disease and Molecular Medicine and Division of Immunology, Department of Pathology, University of Cape Town, Cape Town, South Africa
| | - Erica Smit
- South African Tuberculosis Vaccine Initiative (SATVI), Institute of Infectious Disease and Molecular Medicine and Division of Immunology, Department of Pathology, University of Cape Town, Cape Town, South Africa
| | - Melissa Murphy
- South African Tuberculosis Vaccine Initiative (SATVI), Institute of Infectious Disease and Molecular Medicine and Division of Immunology, Department of Pathology, University of Cape Town, Cape Town, South Africa
| | - Asma Toefy
- South African Tuberculosis Vaccine Initiative (SATVI), Institute of Infectious Disease and Molecular Medicine and Division of Immunology, Department of Pathology, University of Cape Town, Cape Town, South Africa
| | - Lesedi Lerumo
- South African Tuberculosis Vaccine Initiative (SATVI), Institute of Infectious Disease and Molecular Medicine and Division of Immunology, Department of Pathology, University of Cape Town, Cape Town, South Africa
| | - Christiaan Hopley
- South African Tuberculosis Vaccine Initiative (SATVI), Institute of Infectious Disease and Molecular Medicine and Division of Immunology, Department of Pathology, University of Cape Town, Cape Town, South Africa
| | - Bernadette Pienaar
- South African Tuberculosis Vaccine Initiative (SATVI), Institute of Infectious Disease and Molecular Medicine and Division of Immunology, Department of Pathology, University of Cape Town, Cape Town, South Africa
| | - Phalkun Chheng
- Tuberculosis Research Unit, Department of Medicine, Case Western Reserve University and University Hospitals Case Medical Center, Cleveland, OH, U.S.A
| | - Elisa Nemes
- South African Tuberculosis Vaccine Initiative (SATVI), Institute of Infectious Disease and Molecular Medicine and Division of Immunology, Department of Pathology, University of Cape Town, Cape Town, South Africa
| | - Daniel F. Hoft
- Division of Immunobiology, Departments of Internal Medicine and Molecular Biology, Saint Louis University Medical Center, and Center for Vaccine Development, Saint Louis, MO, USA
| | - Willem A. Hanekom
- South African Tuberculosis Vaccine Initiative (SATVI), Institute of Infectious Disease and Molecular Medicine and Division of Immunology, Department of Pathology, University of Cape Town, Cape Town, South Africa
| | - W. Henry Boom
- Tuberculosis Research Unit, Department of Medicine, Case Western Reserve University and University Hospitals Case Medical Center, Cleveland, OH, U.S.A
| | - Mark Hatherill
- South African Tuberculosis Vaccine Initiative (SATVI), Institute of Infectious Disease and Molecular Medicine and Division of Immunology, Department of Pathology, University of Cape Town, Cape Town, South Africa
| | - Thomas J. Scriba
- South African Tuberculosis Vaccine Initiative (SATVI), Institute of Infectious Disease and Molecular Medicine and Division of Immunology, Department of Pathology, University of Cape Town, Cape Town, South Africa,Corresponding Author
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Punkvang A, Saparpakorn P, Hannongbua S, Wolschann P, Pungpo P. Elucidating drug-enzyme interactions and their structural basis for improving the affinity and potency of isoniazid and its derivatives based on computer modeling approaches. Molecules 2010; 15:2791-813. [PMID: 20428080 PMCID: PMC6257264 DOI: 10.3390/molecules15042791] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2010] [Revised: 03/31/2010] [Accepted: 04/07/2010] [Indexed: 11/16/2022] Open
Abstract
The enoyl-ACP reductase enzyme (InhA) from M. tuberculosis is recognized as the primary target of isoniazid (INH), a first-line antibiotic for tuberculosis treatment. To identify the specific interactions of INH-NAD adduct and its derivative adducts in InhA binding pocket, molecular docking calculations and quantum chemical calculations were performed on a set of INH derivative adducts. Reliable binding modes of INH derivative adducts in the InhA pocket were established using the Autodock 3.05 program, which shows a good ability to reproduce the X-ray bound conformation with rmsd of less than 1.0 A. The interaction energies of the INH-NAD adduct and its derivative adducts with individual amino acids in the InhA binding pocket were computed based on quantum chemical calculations at the MP2/6-31G (d) level. The molecular docking and quantum chemical calculation results reveal that hydrogen bond interactions are the main interactions for adduct binding. To clearly delineate the linear relationship between structure and activity of these adducts, CoMFA and CoMSIA models were set up based on molecular docking alignment. The resulting CoMFA and CoMSIA models are in conformity with the best statistical qualities, in which r2cv is 0.67 and 0.74, respectively. Structural requirements of isoniazid derivatives that can be incorporated into the isoniazid framework to improve the activity have been identified through CoMFA and CoMSIA steric and electrostatic contour maps. The integrated results from structure-based, ligand-based design approaches and quantum chemical calculations provide useful structural information facilitating the design of new and more potentially effective antitubercular agents as follow: the R substituents of isoniazid derivatives should contain a large plane and both sides of the plane should contain an electropositive group. Moreover, the steric and electrostatic fields of the 4-pyridyl ring are optimal for greater potency.
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Affiliation(s)
- Auradee Punkvang
- Department of Chemistry, Ubon Ratchathani University, 85 Sthollmark Rd., Warinchamrap, Ubonratchathani, 34190, Thailand
| | | | - Supa Hannongbua
- Department of Chemistry, Kasetsart University, Chatuchak, Bangkok, 10900, Thailand
| | - Peter Wolschann
- Institute for Theoretical Chemistry, University of Vienna, A-1090 Vienna, Austria
| | - Pornpan Pungpo
- Department of Chemistry, Ubon Ratchathani University, 85 Sthollmark Rd., Warinchamrap, Ubonratchathani, 34190, Thailand
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Gupta A, Bhakta S, Kundu S, Gupta M, Srivastava BS, Srivastava R. Fast-growing, non-infectious and intracellularly surviving drug-resistant Mycobacterium aurum: a model for high-throughput antituberculosis drug screening. J Antimicrob Chemother 2009; 64:774-81. [PMID: 19656786 DOI: 10.1093/jac/dkp279] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
OBJECTIVES Enoyl acyl-carrier-protein reductase (InhA), the primary endogenous target for isoniazid and ethionamide, is crucial to type-II fatty acid biosynthesis (FAS-II). The objectives of this study were first to generate InhA mutants of Mycobacterium aurum, secondly to characterize InhA-mediated isoniazid and ethionamide resistance mechanisms across those mutants and finally to investigate the interaction of InhA with enzymes in the FAS-II pathway in M. aurum. METHODS Spontaneous mutants were generated by isoniazid overdose and limited broth dilution, while for genetically modified mutants sense-antisense DNA technology was used. Southern hybridization and immunoprecipitation were both used to identify the InhA homologue in M. aurum. The latter method was further used to compare the level of InhA expression in M. aurum with that in corresponding mutants. Isoniazid/ethionamide susceptibility modulation was examined in vitro and ex vivo using a resazurin assay as well as by cfu counting. In addition, circular dichroism and the bacterial two-hybrid system were exploited to investigate the interaction of InhA with other enzymes of the FAS-II pathway. RESULTS A Mycobacterium tuberculosis InhA homologue was detected in M. aurum. Susceptibility to isoniazid/ethionamide was significantly altered in genetically modified mutants and simultaneously InhA was overexpressed in both spontaneous and genetically modified mutants. InhA interacts with other FAS-II enzymes of M. aurum in vivo. CONCLUSION Close resemblance of isoniazid/ethionamide action on InhA between M. tuberculosis and M. aurum further supports the use of fast-growing and intracellularly surviving drug-resistant M. aurum to substitute for highly virulent, extremely slow-growing M. tuberculosis strains in the early stage of antituberculosis inhibitor screening.
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Affiliation(s)
- Antima Gupta
- Microbiology Division, Central Drug Research Institute, Lucknow 226001, Uttar Pradesh, India.
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Wheeler PR, Brosch R, Coldham NG, Inwald JK, Hewinson RG, Gordon SV. Functional analysis of a clonal deletion in an epidemic strain of Mycobacterium bovis reveals a role in lipid metabolism. MICROBIOLOGY-SGM 2009; 154:3731-3742. [PMID: 19047741 DOI: 10.1099/mic.0.2008/022269-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Previous work on the population structure of Mycobacterium bovis strains in Great Britain has identified highly successful clones which are expanding across the country. One such clone, designated M. bovis type 17, differs from all other members of the Mycobacterium tuberculosis complex in having a region of deletion, termed RDbovis(d)_0173, of seven genes between Mb1963c and Mb1971. Three of these genes have functions annotated in lipid metabolism. To explore the molecular basis for the success of this clone, we examined the impact of this deletion on lipid metabolism. While type 17 isolates had similar lipid composition to other M. bovis strains, their ability to incorporate propanoate into mycolic acids was remarkably low. When expressed as a reciprocal (the ratio of incorporation of label from acetate : propanoate into mycolic acids) the ratio was higher for all three type 17 field strains tested (mean: 18.90) than the values of 7.30 to 7.61 for other field strains (P < 0.002) and values < 6.50 for all other strains in the M. tuberculosis complex tested. The label from propanoate was diverted to pyruvate, at significantly higher levels in M. bovis type 17 than all other strains (P < 0.021). Complementation of M. bovis type 17 with an integrating cosmid, IE471, carrying the M. tuberculosis orthologues of Mb1963c-Mb1971 resulted in the ability of the recombinant strain to incorporate label from propanoate into mycolic acids in a manner similar to other strains. M. bovis type 17 : : IE471 labelled pyruvate from propanoate about four times more slowly than the parent strain. Thus, RDbovis(d)_0173 results in a profound effect on carbon metabolism, providing the ability to compensate for the inactivation of the ald and pykA genes, involved in pyruvate metabolism, that is seen in M. bovis (but not in M. tuberculosis). This shift in carbon metabolism may be a factor in the extraordinary clonal expansion reported for M. bovis type 17.
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Affiliation(s)
| | - Roland Brosch
- Institut Pasteur, UP Pathogénomique Mycobactérienne Intégrée, 25, Rue du Dr Roux, 75015 Paris, France
| | | | | | | | - Stephen V Gordon
- School of Agriculture, Food Science and Veterinary Medicine, College of Life Sciences, University College Dublin, Ireland.,School of Biomolecular Science, School of Medicine and Medical Science, College of Life Sciences, University College Dublin, Ireland.,School of Biomedical Science, School of Medicine and Medical Science, College of Life Sciences, University College Dublin, Ireland.,VLA Weybridge, New Haw, Addlestone KT15 3NB, Surrey, UK
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Analysis of lipid biosynthesis and location. Methods Mol Biol 2009. [PMID: 20560057 DOI: 10.1007/978-1-59745-207-6_5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
A procedure for metabolic labeling of all cellular lipids starting with a culture of mycobacteria is described in this chapter using either a pulse-chase or a simple labeling experimental design. Three fractions are produced for subsequent lipid analysis: (1) the culture filtrate; (2) a readily released surface lipid fraction; and (3) the killed, labeled bacteria. A standardized, TLC-based method for general lipid analysis that can be used to quantify the labeling of all the mycobacterial lipids is given as well as a protocol for analyzing the fatty acyl moieties of the lipids.
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Gupta N, Singh B. Decipheringkasoperon locus inMycobacterium aurumand genesis of a recombinant strain for rational-based drug screening. J Appl Microbiol 2008; 105:1703-10. [DOI: 10.1111/j.1365-2672.2008.03888.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Rémond C, Plantier-Royon R, Aubry N, O'Donohue MJ. An original chemoenzymatic route for the synthesis of β-d-galactofuranosides using an α-l-arabinofuranosidase. Carbohydr Res 2005; 340:637-44. [PMID: 15721334 DOI: 10.1016/j.carres.2005.01.016] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2004] [Accepted: 01/20/2005] [Indexed: 11/28/2022]
Abstract
DGalactofuranose is a widespread component of cell wall polysaccharides in bacteria, protozoa and fungi, but is totally absent in mammals. Importantly, galactofuranose is a key constituent of major cell envelope polysaccharides in pathogenic mycobacteria. In this respect, galactofuranose-based glycoconjugates are interesting target molecules for drug design. O-Glycosidases and notably beta-D-galactofuranosidases could be useful tools for the chemoenzymatic synthesis of galactofuranosides, but to date no studies of this type have been reported. Here we report the use of a GH 51 alpha-l-arabinofuranosidase for the synthesis of beta-D-galactofuranosides. We have demonstrated that this enzyme can catalyse both the autocondensation of p-nitrophenyl-beta-D-galactofuranoside and the transgalactofuranosylation of benzyl alpha-D-xylopyranoside, forming p-nitrophenyl beta-D-galactofuranosyl-(1-->2)-beta-D-galactofuranoside and benzyl beta-D-galactofuranosyl-(1-->2)-alpha-D-xylopyranoside, respectively. Both reactions were very regiospecific and the reaction involving benzyl alpha-D-xylopyranoside afforded very high yields (74.8%) of the major product. To our knowledge, this demonstration of chemoenzymatic synthesis of galactofuranosides constitutes the very first use of an O-glycosidase for the synthesis of galactofuranosides.
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Affiliation(s)
- Caroline Rémond
- Laboratoire de Technologie Enzymatique et Physico-chimie des Agroressources, UMR URCA/INRA FARE, 8 rue Gabriel Voisin, BP 316, F-51688 Reims, France
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Bhakta S, Besra GS, Upton AM, Parish T, Sholto-Douglas-Vernon C, Gibson KJC, Knutton S, Gordon S, DaSilva RP, Anderton MC, Sim E. Arylamine N-acetyltransferase is required for synthesis of mycolic acids and complex lipids in Mycobacterium bovis BCG and represents a novel drug target. ACTA ACUST UNITED AC 2004; 199:1191-9. [PMID: 15117974 PMCID: PMC2211905 DOI: 10.1084/jem.20031956] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Mycolic acids represent a major component of the unique cell wall of mycobacteria. Mycolic acid biosynthesis is inhibited by isoniazid, a key frontline antitubercular drug that is inactivated by mycobacterial and human arylamine N-acetyltransferase (NAT). We show that an in-frame deletion of Mycobacterium bovis BCG nat results in delayed entry into log phase, altered morphology, altered cell wall lipid composition, and increased intracellular killing by macrophages. In particular, deletion of nat perturbs biosynthesis of mycolic acids and their derivatives and increases susceptibility of M. bovis BCG to antibiotics that permeate the cell wall. Phenotypic traits are fully complemented by introduction of Mycobacterium tuberculosis nat. We infer from our findings that NAT is critical to normal mycolic acid synthesis and hence other derivative cell wall components and represents a novel target for antituberculosis therapy. In addition, this is the first report of an endogenous role for NAT in mycobacteria.
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Affiliation(s)
- Sanjib Bhakta
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford OX1 3QT, UK
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Abstract
Fatty acid biosynthesis, the first stage in membrane lipid biogenesis, is catalyzed in most bacteria by a series of small, soluble proteins that are each encoded by a discrete gene (Fig. 1; Table 1). This arrangement is termed the type II fatty acid synthase (FAS) system and contrasts sharply with the type I FAS of eukaryotes which is a dimer of a single large, multifunctional polypeptide. Thus, the bacterial pathway offers several unique sites for selective inhibition by chemotherapeutic agents. The site of action of isoniazid, used in the treatment of tuberculosis for 50 years, and the consumer antimicrobial agent triclosan were revealed recently to be the enoyl-ACP reductase of the type II FAS. The fungal metabolites, cerulenin and thiolactomycin, target the condensing enzymes of the bacterial pathway while the dehydratase/isomerase is inhibited by a synthetic acetylenic substrate analogue. Transfer of fatty acids to the membrane has also been inhibited via interference with the first acyltransferase step, while a new class of drugs targets lipid A synthesis. This review will summarize the data generated on these inhibitors to date, and examine where additional efforts will be required to develop new chemotherapeutics to help combat microbial infections.
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Affiliation(s)
- R J Heath
- Protein Science Division, Department of Infectious Diseases, St. Jude Children's Research Hospital, Tennessee 38105, Memphis, USA.
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Marrakchi H, Lanéelle G, Quémard AK. InhA, a target of the antituberculous drug isoniazid, is involved in a mycobacterial fatty acid elongation system, FAS-II. MICROBIOLOGY (READING, ENGLAND) 2000; 146 ( Pt 2):289-296. [PMID: 10708367 DOI: 10.1099/00221287-146-2-289] [Citation(s) in RCA: 146] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Most drug-resistant clinical isolates of the tubercle bacillus are resistant to isoniazid, a first-line antituberculous drug. This antibiotic was shown to act on Mycobacterium tuberculosis by inhibiting a 2-trans-enoyl-acyl carrier protein reductase, called InhA. However, the exact role played by InhA in mycobacteria remained unclear. A mycobacterial enzyme fraction containing InhA was isolated. It displays a long-chain fatty acid elongation activity with the characteristic properties described for the FAS-II (fatty acid synthetase II) system. Inhibition of this activity by InhA inhibitors, namely isoniazid, hexadecynoyl-CoA or octadecynoyl-CoA, showed that InhA belongs to the FAS-II system. Moreover, the InhA inhibitors also blocked the biosynthesis of mycolic acids, which are major lipids of the mycobacterial envelope. The data strongly suggest that isoniazid acts on the mycobacterial cell wall by preventing the FAS-II system from producing long-chain fatty acid precursors for mycolic acid biosynthesis.
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Affiliation(s)
- Hedia Marrakchi
- Institut de Pharmacologie et de Biologie Structurale, Centre National de la Recherche Scientifique, 205 route de Narbonne, 31077 Toulouse cedex, France1
| | - Gilbert Lanéelle
- Institut de Pharmacologie et de Biologie Structurale, Centre National de la Recherche Scientifique, 205 route de Narbonne, 31077 Toulouse cedex, France1
| | - Annaı K Quémard
- Institut de Pharmacologie et de Biologie Structurale, Centre National de la Recherche Scientifique, 205 route de Narbonne, 31077 Toulouse cedex, France1
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Rozwarski DA, Vilchèze C, Sugantino M, Bittman R, Sacchettini JC. Crystal structure of the Mycobacterium tuberculosis enoyl-ACP reductase, InhA, in complex with NAD+ and a C16 fatty acyl substrate. J Biol Chem 1999; 274:15582-9. [PMID: 10336454 DOI: 10.1074/jbc.274.22.15582] [Citation(s) in RCA: 206] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Enoyl-ACP reductases participate in fatty acid biosynthesis by utilizing NADH to reduce the trans double bond between positions C2 and C3 of a fatty acyl chain linked to the acyl carrier protein. The enoyl-ACP reductase from Mycobacterium tuberculosis, known as InhA, is a member of an unusual FAS-II system that prefers longer chain fatty acyl substrates for the purpose of synthesizing mycolic acids, a major component of mycobacterial cell walls. The crystal structure of InhA in complex with NAD+ and a C16 fatty acyl substrate, trans-2-hexadecenoyl-(N-acetylcysteamine)-thioester, reveals that the substrate binds in a general "U-shaped" conformation, with the trans double bond positioned directly adjacent to the nicotinamide ring of NAD+. The side chain of Tyr158 directly interacts with the thioester carbonyl oxygen of the C16 fatty acyl substrate and therefore could help stabilize the enolate intermediate, proposed to form during substrate catalysis. Hydrophobic residues, primarily from the substrate binding loop (residues 196-219), engulf the fatty acyl chain portion of the substrate. The substrate binding loop of InhA is longer than that of other enoyl-ACP reductases and creates a deeper substrate binding crevice, consistent with the ability of InhA to recognize longer chain fatty acyl substrates.
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Affiliation(s)
- D A Rozwarski
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, New York 10461, USA
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Salman M, Brennan PJ, Lonsdale JT. Synthesis of mycolic acids of mycobacteria: an assessment of the cell-free system in light of the whole genome. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1437:325-32. [PMID: 10101266 DOI: 10.1016/s1388-1981(99)00026-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Mycolic acids are 70-90 carbon, alpha-alkyl, beta-hydroxy fatty acids constituting a major component of the cell envelope of Mycobacterium tuberculosis. The fact that the mycolic acid biosynthetic pathway is both essential in mycobacteria and the target for many first-line anti-TB drugs necessitates a detailed understanding of its biochemistry. A whole cell-free, but cell particulate- and membrane-containing enzyme preparation for mycolic acid biosynthesis was developed a few years ago and studied extensively. This system was shown to catalyze the synthesis of mature mycolic acids from [14C]acetate, but allows only minimal deposition into the cell wall proper. In the meantime the sequence of the entire genome of M. tuberculosis has been elucidated and its analysis using numerous protein sequence-based algorithms predicted cytoplasmic localization and a soluble, not a particulate, nature for the enzymes involved in the mycolic acid synthetic pathway. Accordingly, we re-assessed the 'cell-free' system for mycolic acid synthesis and concluded that it is probably due to the presence of unbroken cells, since viable cells were recovered from the cell wall preparation. The amount of whole cells depended upon the efficiency of the cell disruption method and conditions, and the amount of mycolic acid synthesized by the putative cell-free system correlated with the content of whole cells. Thus, accumulated results from the use of this 'cell-free' cell wall-based system should be re-evaluated in the light of these new data.
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Affiliation(s)
- M Salman
- SmithKline Beecham Pharmaceuticals, 1250 S. Collegeville Rd., PO Box 5089, Collegeville, PA 19403, USA.
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Banerjee A, Sugantino M, Sacchettini JC, Jacobs WR. The mabA gene from the inhA operon of Mycobacterium tuberculosis encodes a 3-ketoacyl reductase that fails to confer isoniazid resistance. MICROBIOLOGY (READING, ENGLAND) 1998; 144 ( Pt 10):2697-2704. [PMID: 9802011 DOI: 10.1099/00221287-144-10-2697] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
A target of the anti-tuberculosis drugs isoniazid (INH) and ethionamide (ETH) has been shown to be an enoyl reductase, encoded by the inhA gene. The mabA (mycolic acid biosynthesis A) gene is located immediately upstream of inhA in Mycobacterium tuberculosis, Mycobacterium bovis and Mycobacterium smegmatis. The MabA protein from M. tuberculosis was expressed in Escherichia coli and shown to have 3-ketoacyl reductase activity, consistent with a role in mycolic acid biosynthesis. In M. smegmatis, inhA and mabA are independently transcribed, but in M. tuberculosis and M. bovis BCG, mabA and inhA constitute a single operon. Several INH-ETH-resistant M. tuberculosis clinical isolates contain point mutations in the ribosome-binding site of mabA in the mabA-inhA operon. However, genetic dissection of this operon reveals that the INH-ETH-resistance phenotype is encoded only by inhA, and not by mabA.
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Affiliation(s)
- Asesh Banerjee
- Department of Microbiology and Immunologyl, Howard Hughes Medical Institute, and Department of Biochemistry
| | | | | | - William R Jacobs
- Department of Microbiology and Immunologyl, Howard Hughes Medical Institute, and Department of Biochemistry
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15
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Affiliation(s)
- B J Rawlings
- Department of Chemistry, University of Leicester, UK.
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16
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Rozwarski DA, Grant GA, Barton DH, Jacobs WR, Sacchettini JC. Modification of the NADH of the isoniazid target (InhA) from Mycobacterium tuberculosis. Science 1998; 279:98-102. [PMID: 9417034 DOI: 10.1126/science.279.5347.98] [Citation(s) in RCA: 501] [Impact Index Per Article: 19.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The preferred antitubercular drug isoniazid specifically targets a long-chain enoyl-acyl carrier protein reductase (InhA), an enzyme essential for mycolic acid biosynthesis in Mycobacterium tuberculosis. Despite the widespread use of this drug for more than 40 years, its precise mode of action has remained obscure. Data from x-ray crystallography and mass spectrometry reveal that the mechanism of isoniazid action against InhA is covalent attachment of the activated form of the drug to the nicotinamide ring of nicotinamide adenine dinucleotide bound within the active site of InhA.
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Affiliation(s)
- D A Rozwarski
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA
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17
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Abstract
The review discusses current knowledge of the biosynthesis, composition and arrangement of the mycobacterial envelope, describes the biological activities of the constituents and considers how these activities may be relevant to the pathology of mycobacterial disease. The envelope possesses three structural components: plasma membrane, wall and capsule. Although the major biomolecules occurring in each of these parts are known, the distribution of numerous minor substances is poorly understood; an attempt has been made to assign them to particular positions on rational grounds. The plasma membrane appears to be a typical bacterial membrane but, though vital to the mycobacterium, probably plays little part in pathological processes. The wall partly resembles a Gram-positive wall, but is unusual in having a layer of lipid (mycolate esters) which is probably arranged to form a permeability barrier to polar molecules. The capsule, whose chemical composition has only recently been recognized, consists of polysaccharide and protein with traces of lipid; the arrangement of these components is imperfectly understood. Constituents of all parts of the envelope have biological activities which may be relevant. The likely importance of these activities in the overall effect of the envelope is considered.
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Affiliation(s)
- M Daffé
- Institut de Pharmacologie et de Biologie Structurale, Toulouse, France
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18
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Menéndez MC, Ainsa JA, Martín C, García MJ. katGI and katGII encode two different catalases-peroxidases in Mycobacterium fortuitum. J Bacteriol 1997; 179:6880-6. [PMID: 9371430 PMCID: PMC179624 DOI: 10.1128/jb.179.22.6880-6886.1997] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
It has been suggested that catalase-peroxidase plays an important role in several aspects of mycobacterial metabolism and is a virulence factor in the main pathogenic mycobacteria. In this investigation, we studied genes encoding for this protein in the fast-growing opportunistic pathogen Mycobacterium fortuitum. Nucleotide sequences of two different catalase-peroxidase genes (katGI and katGII) of M. fortuitum are described. They show only 64% homology at the nucleotide level and 55% identity at the amino acid level, and they are more similar to catalases-peroxidases from different bacteria, including mycobacteria, than to each other. Both proteins were found to be expressed in actively growing M. fortuitum, and both could also be expressed when transformed into Escherichia coli and M. aurum. We detected the presence of a copy of IS6100 in the neighboring region of a katG gene in the M. fortuitum strain in which this element was identified (strain FC1). The influence of each katG gene on isoniazid (isonicotinic acid hydrazide; INH) susceptibility of mycobacteria was checked by using the INH-sensitive M. aurum as the host. Resistance to INH was induced when katGI was transformed into INH-sensitive M. aurum, suggesting that this enzyme contributes to the natural resistance of M. fortuitum to the drug. This is the first report showing two different genes encoding same enzyme activity which are actively expressed within the same mycobacterial strain.
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Affiliation(s)
- M C Menéndez
- Departamento Medicina Preventiva, Facultad de Medicina, Universidad Autónoma de Madrid, Spain
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