1
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Harrison GA, Wang ER, Cho K, Mreyoud Y, Sarkar S, Almqvist F, Patti GJ, Stallings CL. Inducing vulnerability to InhA inhibition restores isoniazid susceptibility in drug-resistant Mycobacterium tuberculosis. mBio 2024; 15:e0296823. [PMID: 38294237 PMCID: PMC10936210 DOI: 10.1128/mbio.02968-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2023] [Accepted: 12/20/2023] [Indexed: 02/01/2024] Open
Abstract
Of the approximately 10 million cases of Mycobacterium tuberculosis (Mtb) infections each year, over 10% are resistant to the frontline antibiotic isoniazid (INH). INH resistance is predominantly caused by mutations that decrease the activity of the bacterial enzyme KatG, which mediates the conversion of the pro-drug INH to its active form INH-NAD. We previously discovered an inhibitor of Mtb respiration, C10, that enhances the bactericidal activity of INH, prevents the emergence of INH-resistant mutants, and re-sensitizes a collection of INH-resistant mutants to INH through an unknown mechanism. To investigate the mechanism of action of C10, we exploited the toxicity of high concentrations of C10 to select for resistant mutants. We discovered two mutations that confer resistance to the disruption of energy metabolism and allow for the growth of Mtb in high C10 concentrations, indicating that growth inhibition by C10 is associated with inhibition of respiration. Using these mutants as well as direct inhibitors of the Mtb electron transport chain, we provide evidence that inhibition of energy metabolism by C10 is neither sufficient nor necessary to potentiate killing by INH. Instead, we find that C10 acts downstream of INH-NAD synthesis, causing Mtb to become particularly sensitive to inhibition of the INH-NAD target, InhA, without changing the concentration of INH-NAD or the activity of InhA, the two predominant mechanisms of potentiating INH. Our studies revealed that there exists a vulnerability in Mtb that can be exploited to render Mtb sensitive to otherwise subinhibitory concentrations of InhA inhibitor.IMPORTANCEIsoniazid (INH) is a critical frontline antibiotic to treat Mycobacterium tuberculosis (Mtb) infections. INH efficacy is limited by its suboptimal penetration of the Mtb-containing lesion and by the prevalence of clinical INH resistance. We previously discovered a compound, C10, that enhances the bactericidal activity of INH, prevents the emergence of INH-resistant mutants, and re-sensitizes a set of INH-resistant mutants to INH. Resistance is typically mediated by katG mutations that decrease the activation of INH, which is required for INH to inhibit the essential enzyme InhA. Our current work demonstrates that C10 re-sensitizes INH-resistant katG-hypomorphs without enhancing the activation of INH. We furthermore show that C10 causes Mtb to become particularly vulnerable to InhA inhibition without compromising InhA activity on its own. Therefore, C10 represents a novel strategy to curtail the development of INH resistance and to sensitize Mtb to sub-lethal doses of INH, such as those achieved at the infection site.
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Affiliation(s)
- Gregory A. Harrison
- Department of Molecular Microbiology, Center for Women’s Infectious Disease Research, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Erin R. Wang
- Department of Molecular Microbiology, Center for Women’s Infectious Disease Research, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Kevin Cho
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri, USA
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
- Center for Metabolomics and Isotope Tracing, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Yassin Mreyoud
- Department of Molecular Microbiology, Center for Women’s Infectious Disease Research, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Souvik Sarkar
- Department of Chemistry, Umeå University, Umeå, Sweden
| | - Fredrik Almqvist
- Department of Chemistry, Umeå University, Umeå, Sweden
- Umeå Centre for Microbial Research, UCMR, Umeå University, Umeå, Sweden
| | - Gary J. Patti
- Department of Chemistry, Washington University in St. Louis, St. Louis, Missouri, USA
- Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
- Center for Metabolomics and Isotope Tracing, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Christina L. Stallings
- Department of Molecular Microbiology, Center for Women’s Infectious Disease Research, Washington University School of Medicine, St. Louis, Missouri, USA
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2
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Fujihara M, Kondoh D, Matsuzawa S, Naito I. Electron microscopic observation of Mycobacterium avium subsp. paratuberculosis in cattle feces after a novel purification using liquid paraffin. J Microbiol Methods 2024; 217-218:106891. [PMID: 38302060 DOI: 10.1016/j.mimet.2024.106891] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2023] [Revised: 01/29/2024] [Accepted: 01/29/2024] [Indexed: 02/03/2024]
Abstract
We developed a novel method for purifying acid-fast bacteria from feces. The method enabled the observation of characteristic clumps of Mycobacterium avium subsp. paratuberculosis (MAP) under electron microscopy by removing contaminants and other bacteria. Further refinement of this method will contribute to efficient and effective MAP detection.
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Affiliation(s)
- Masatoshi Fujihara
- Hokkaido Kushiro Livestock Hygiene Service Center, Kushiro, Hokkaido, Japan.
| | - Daisuke Kondoh
- Department of Veterinary Medicine, Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido, Japan.
| | - Shigeru Matsuzawa
- Hokkaido Kushiro Livestock Hygiene Service Center, Kushiro, Hokkaido, Japan.
| | - Ikunori Naito
- Local Independent Administrative Agency Hokkaido Research Organization, Shintoku, Hokkaido, Japan.
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3
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Chiu CH, Tan JJY, Mondal S, Lin CH, Mong KKT. Sulfoglycolipids and Related Analogues of Mycobacterium tuberculosis: Chemical Synthesis and Immunological Studies. ChemMedChem 2023; 18:e202300399. [PMID: 37788979 DOI: 10.1002/cmdc.202300399] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2023] [Revised: 10/02/2023] [Accepted: 10/03/2023] [Indexed: 10/05/2023]
Abstract
Mycobacterium tuberculosis (Mtb) causes tuberculosis as one major threat to human health, which has been deteriorated owing to the emerging multidrug resistance. Mtb contains a complex lipophilic cell wall structure that is important for bacterial persistence. Among the lipid components, sulfoglycolipids (SGLs), known to induce immune cell responses, are composed of a trehalose core attached with a conserved sulfate group and 1-4 fatty acyl chains in an asymmetric pattern. At least one of these acyl chains is polymethylated with 3-12 methyl branches. Although Mtb SGL can be isolated from bacterial culture, resulting SGL is still a homologous mixture, impeding accurate research studies. This up-to-date review covers the chemical synthesis and immunological studies of Mtb SGLs and structural analogues, with an emphasis on the development of new glycosylation methods and the asymmetric synthesis of polymethylated scaffolds. Both are critical to advance further research on biological functions of these complicated SGLs.
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Affiliation(s)
- Cheng-Hsin Chiu
- Applied Chemistry Department, National Yang Ming Chiao Tung University, No. 1001, University Road, Hsinchu City, 30010, Taiwan (China
| | - Janet Jia-Yin Tan
- Institute of Biological Chemistry, Academia Sinica, No. 128, Academia Road Section 2, Nan-Kang, 11529, Taiwan (China
| | - Soumik Mondal
- Applied Chemistry Department, National Yang Ming Chiao Tung University, No. 1001, University Road, Hsinchu City, 30010, Taiwan (China
| | - Chun-Hung Lin
- Institute of Biological Chemistry, Academia Sinica, No. 128, Academia Road Section 2, Nan-Kang, 11529, Taiwan (China
- Department of Chemistry and Institute of Biochemical Sciences, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei, 10617, Taiwan (China
| | - Kwok-Kong Tony Mong
- Applied Chemistry Department, National Yang Ming Chiao Tung University, No. 1001, University Road, Hsinchu City, 30010, Taiwan (China
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4
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Harrison GA, Cho K, Wang ER, Sarkar S, Almqvist F, Patti GJ, Stallings CL. Inducing vulnerability to InhA inhibition restores isoniazid susceptibility in drug resistant Mycobacterium tuberculosis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.06.527416. [PMID: 36798348 PMCID: PMC9934558 DOI: 10.1101/2023.02.06.527416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
Of the approximately 10 million cases of Mycobacterium tuberculosis (Mtb) infections each year, over 10% are resistant to the frontline antibiotic isoniazid (INH). INH resistance is predominantly caused by mutations that decrease the activity of the bacterial enzyme KatG, which mediates conversion of the pro-drug INH to its active form INH-NAD. We previously discovered an inhibitor of Mtb respiration, C10, that enhances the bactericidal activity of INH, prevents the emergence of INH-resistant mutants, and re-sensitizes a collection of INH-resistant mutants to INH through an unknown mechanism. To investigate the mechanism of action of C10, we exploited the toxicity of high concentrations of C10 to select for resistant mutants. We discovered two mutations that confer resistance to the disruption of energy metabolism and allow for growth of Mtb in high C10 concentrations, indicating that growth inhibition by C10 is associated with inhibition of respiration. Using these mutants as well as direct inhibitors of the Mtb electron transport chain, we provide evidence that inhibition of energy metabolism by C10 is neither sufficient nor necessary to potentiate killing by INH. Instead, we find that C10 acts downstream of INH-NAD synthesis, causing Mtb to become particularly sensitive to inhibition of the INH-NAD target, InhA, without changing the concentration of INH-NAD or the activity of InhA, the two predominant mechanisms of potentiating INH. Our studies revealed that there exists a vulnerability in Mtb that can be exploited to render Mtb sensitive to otherwise subinhibitory concentrations of InhA inhibitor.
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Affiliation(s)
- Gregory A. Harrison
- Department of Molecular Microbiology, Center for Women’s Infectious Disease Research, Washington University School of Medicine, Saint Louis, MO, USA
| | - Kevin Cho
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO, USA
- Department of Medicine, Washington University School of Medicine, Saint Louis, MO, USA
- Center for Metabolomics and Isotope Tracing, Washington University in St. Louis, St. Louis, MO USA
| | - Erin R. Wang
- Department of Molecular Microbiology, Center for Women’s Infectious Disease Research, Washington University School of Medicine, Saint Louis, MO, USA
| | - Souvik Sarkar
- Department of Chemistry, Umeå University, SE-90187 Umeå, Sweden
| | - Fredrik Almqvist
- Department of Chemistry, Umeå University, SE-90187 Umeå, Sweden
- Umeå Centre for Microbial Research, UCMR, Umeå University, SE-90187 Umeå, Sweden
| | - Gary J. Patti
- Department of Chemistry, Washington University in St. Louis, St. Louis, MO, USA
- Department of Medicine, Washington University School of Medicine, Saint Louis, MO, USA
- Center for Metabolomics and Isotope Tracing, Washington University in St. Louis, St. Louis, MO USA
| | - Christina L. Stallings
- Department of Molecular Microbiology, Center for Women’s Infectious Disease Research, Washington University School of Medicine, Saint Louis, MO, USA
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5
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Enhanced immunogenicity of Mycobacterium bovis BCG through CRISPRi mediated depletion of AftC. Cell Surf 2022; 8:100088. [PMID: 36405350 PMCID: PMC9651938 DOI: 10.1016/j.tcsw.2022.100088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Revised: 11/08/2022] [Accepted: 11/08/2022] [Indexed: 11/13/2022] Open
Abstract
Mycobacterium tuberculosis causes the disease tuberculosis and affects a third of the world’s population. The recent COVID-19 pandemic exacerbated the situation with a projected 27% increase in tuberculosis related deaths. M. tuberculosis has an elaborate cell wall consisting of peptidoglycan, arabinogalactan and mycolic acids which shield the bacilli from the toxic bactericidal milieu within phagocytes. Amongst, the numerous glycosyltransferase enzymes involved in mycobacterial cell wall biosynthesis, arabinofuranosyltransferase C (aftC) is responsible for the branching of the arabinan domain in both arabinogalactan and lipoarabinomannan. Using Clustered Regularly Interspaced Short Palindromic Repeats interference (CRISPRi) we have generated aftC knockdowns in Mycobacterium bovis BCG and demonstrated the generation of a truncated, immunogenic lipoarabinomannan within its cell envelope. The aftC depleted BCG mutants were unable to form characteristic mycobacterial pellicular biofilms and elicit a potent immunostimulatory phenotype compared to wild type M. bovis BCG in a THP1 cell line. This study paves the way to further explore novel BCG mutants as promising vaccine boosters in preventing pulmonary tuberculosis.
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6
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Galy R, Ballereau S, Génisson Y, Mourey L, Plaquevent JC, Maveyraud L. Fragment-Based Ligand Discovery Applied to the Mycolic Acid Methyltransferase Hma (MmaA4) from Mycobacterium tuberculosis: A Crystallographic and Molecular Modelling Study. Pharmaceuticals (Basel) 2021; 14:ph14121282. [PMID: 34959681 PMCID: PMC8708032 DOI: 10.3390/ph14121282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2021] [Revised: 11/29/2021] [Accepted: 12/05/2021] [Indexed: 11/16/2022] Open
Abstract
The mycolic acid biosynthetic pathway represents a promising source of pharmacological targets in the fight against tuberculosis. In Mycobacterium tuberculosis, mycolic acids are subject to specific chemical modifications introduced by a set of eight S-adenosylmethionine dependent methyltransferases. Among these, Hma (MmaA4) is responsible for the introduction of oxygenated modifications. Crystallographic screening of a library of fragments allowed the identification of seven ligands of Hma. Two mutually exclusive binding modes were identified, depending on the conformation of residues 147–154. These residues are disordered in apo-Hma but fold upon binding of the S-adenosylmethionine (SAM) cofactor as well as of analogues, resulting in the formation of the short η1-helix. One of the observed conformations would be incompatible with the presence of the cofactor, suggesting that allosteric inhibitors could be designed against Hma. Chimeric compounds were designed by fusing some of the bound fragments, and the relative binding affinities of initial fragments and evolved compounds were investigated using molecular dynamics simulation and generalised Born and Poisson–Boltzmann calculations coupled to the surface area continuum solvation method. Molecular dynamics simulations were also performed on apo-Hma to assess the structural plasticity of the unliganded protein. Our results indicate a significant improvement in the binding properties of the designed compounds, suggesting that they could be further optimised to inhibit Hma activity.
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Affiliation(s)
- Romain Galy
- Institut de Pharmacologie et de Biologie Structurale, Université Toulouse III—Paul Sabatier, Centre National de la Recherche Scientifique, 31077 Toulouse, France; (R.G.); (L.M.)
| | - Stéphanie Ballereau
- Laboratoire de Synthèse et Physico-Chimie de Molécules d’Intérêt Biologique, Université Toulouse III—Paul Sabatier, Centre National de la Recherche Scientifique, 31062 Toulouse, France; (S.B.); (Y.G.); (J.-C.P.)
| | - Yves Génisson
- Laboratoire de Synthèse et Physico-Chimie de Molécules d’Intérêt Biologique, Université Toulouse III—Paul Sabatier, Centre National de la Recherche Scientifique, 31062 Toulouse, France; (S.B.); (Y.G.); (J.-C.P.)
| | - Lionel Mourey
- Institut de Pharmacologie et de Biologie Structurale, Université Toulouse III—Paul Sabatier, Centre National de la Recherche Scientifique, 31077 Toulouse, France; (R.G.); (L.M.)
| | - Jean-Christophe Plaquevent
- Laboratoire de Synthèse et Physico-Chimie de Molécules d’Intérêt Biologique, Université Toulouse III—Paul Sabatier, Centre National de la Recherche Scientifique, 31062 Toulouse, France; (S.B.); (Y.G.); (J.-C.P.)
| | - Laurent Maveyraud
- Institut de Pharmacologie et de Biologie Structurale, Université Toulouse III—Paul Sabatier, Centre National de la Recherche Scientifique, 31077 Toulouse, France; (R.G.); (L.M.)
- Correspondence: ; Tel.: +33-561-17-54-35
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7
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The thick waxy coat of mycobacteria, a protective layer against antibiotics and the host's immune system. Biochem J 2020; 477:1983-2006. [PMID: 32470138 PMCID: PMC7261415 DOI: 10.1042/bcj20200194] [Citation(s) in RCA: 76] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 04/30/2020] [Accepted: 05/04/2020] [Indexed: 12/22/2022]
Abstract
Tuberculosis, caused by the pathogenic bacterium Mycobacterium tuberculosis (Mtb), is the leading cause of death from an infectious disease, with a mortality rate of over a million people per year. This pathogen's remarkable resilience and infectivity is largely due to its unique waxy cell envelope, 40% of which comprises complex lipids. Therefore, an understanding of the structure and function of the cell wall lipids is of huge indirect clinical significance. This review provides a synopsis of the cell envelope and the major lipids contained within, including structure, biosynthesis and roles in pathogenesis.
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8
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Batt SM, Burke CE, Moorey AR, Besra GS. Antibiotics and resistance: the two-sided coin of the mycobacterial cell wall. Cell Surf 2020; 6:100044. [PMID: 32995684 PMCID: PMC7502851 DOI: 10.1016/j.tcsw.2020.100044] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 08/26/2020] [Accepted: 08/26/2020] [Indexed: 01/07/2023] Open
Abstract
Mycobacterium tuberculosis, the bacterium responsible for tuberculosis, is the global leading cause of mortality from an infectious agent. Part of this success relies on the unique cell wall, which consists of a thick waxy coat with tightly packed layers of complexed sugars, lipids and peptides. This coat provides a protective hydrophobic barrier to antibiotics and the host's defences, while enabling the bacterium to spread efficiently through sputum to infect and survive within the macrophages of new hosts. However, part of this success comes at a cost, with many of the current first- and second-line drugs targeting the enzymes involved in cell wall biosynthesis. The flip side of this coin is that resistance to these drugs develops either in the target enzymes or the activation pathways of the drugs, paving the way for new resistant clinical strains. This review provides a synopsis of the structure and synthesis of the cell wall and the major current drugs and targets, along with any mechanisms of resistance.
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Affiliation(s)
- Sarah M. Batt
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Christopher E. Burke
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Alice R. Moorey
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Gurdyal S. Besra
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
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9
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Shetye GS, Franzblau SG, Cho S. New tuberculosis drug targets, their inhibitors, and potential therapeutic impact. Transl Res 2020; 220:68-97. [PMID: 32275897 DOI: 10.1016/j.trsl.2020.03.007] [Citation(s) in RCA: 88] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Revised: 02/28/2020] [Accepted: 03/09/2020] [Indexed: 11/18/2022]
Abstract
The current tuberculosis (TB) predicament poses numerous challenges and therefore every incremental scientific work and all positive socio-political engagements, are steps taken in the right direction to eradicate TB. Progression of the late stage TB-drug pipeline into the clinics is an immediate deliverable of this global effort. At the same time, fueling basic research and pursuing early discovery work must be sustained to maintain a healthy TB-drug pipeline. This review encompasses a broad analysis of chemotherapeutic strategies that target the DNA replication, protein synthesis, cell wall biosynthesis, energy metabolism and proteolysis of Mycobacterium tuberculosis (Mtb). It includes a status check of the current TB-drug pipeline with a focus on the associated biology, emerging targets, and their promising chemical inhibitors. Potential synergies and/or gaps within or across different chemotherapeutic strategies are systematically reviewed as well.
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Affiliation(s)
- Gauri S Shetye
- Institute for Tuberculosis Research, College of Pharmacy, University of Illinois at Chicago, Chicago, Illinois
| | - Scott G Franzblau
- Institute for Tuberculosis Research, College of Pharmacy, University of Illinois at Chicago, Chicago, Illinois
| | - Sanghyun Cho
- Institute for Tuberculosis Research, College of Pharmacy, University of Illinois at Chicago, Chicago, Illinois.
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10
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Zhang L, Zhao Y, Gao Y, Wu L, Gao R, Zhang Q, Wang Y, Wu C, Wu F, Gurcha SS, Veerapen N, Batt SM, Zhao W, Qin L, Yang X, Wang M, Zhu Y, Zhang B, Bi L, Zhang X, Yang H, Guddat LW, Xu W, Wang Q, Li J, Besra GS, Rao Z. Structures of cell wall arabinosyltransferases with the anti-tuberculosis drug ethambutol. Science 2020; 368:1211-1219. [PMID: 32327601 DOI: 10.1126/science.aba9102] [Citation(s) in RCA: 73] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 02/06/2020] [Accepted: 04/14/2020] [Indexed: 11/02/2022]
Abstract
The arabinosyltransferases EmbA, EmbB, and EmbC are involved in Mycobacterium tuberculosis cell wall synthesis and are recognized as targets for the anti-tuberculosis drug ethambutol. In this study, we determined cryo-electron microscopy and x-ray crystal structures of mycobacterial EmbA-EmbB and EmbC-EmbC complexes in the presence of their glycosyl donor and acceptor substrates and with ethambutol. These structures show how the donor and acceptor substrates bind in the active site and how ethambutol inhibits arabinosyltransferases by binding to the same site as both substrates in EmbB and EmbC. Most drug-resistant mutations are located near the ethambutol binding site. Collectively, our work provides a structural basis for understanding the biochemical function and inhibition of arabinosyltransferases and the development of new anti-tuberculosis agents.
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Affiliation(s)
- Lu Zhang
- Shanghai Institute for Advanced Immunochemical Studies, iHuman Institute, School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China.,State Key Laboratory of Medicinal Chemical Biology, Frontiers Science Center for Cell Response, College of Life Sciences, College of Pharmacy, Nankai University, Tianjin 300353, China
| | - Yao Zhao
- Shanghai Institute for Advanced Immunochemical Studies, iHuman Institute, School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China.,CAS Center for Excellence in Molecular Cell Science, Shanghai Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, Shanghai 200031, China.,University of Chinese Academy of Sciences, Beijing 100101, China
| | - Yan Gao
- Laboratory of Structural Biology, Tsinghua University, Beijing 100084, China
| | - Lijie Wu
- Shanghai Institute for Advanced Immunochemical Studies, iHuman Institute, School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Ruogu Gao
- University of Chinese Academy of Sciences, Beijing 100101, China.,National Laboratory of Biomacromolecules and Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, CAS, Beijing 100101, China
| | - Qi Zhang
- Shanghai Institute for Advanced Immunochemical Studies, iHuman Institute, School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Yinan Wang
- Shanghai Institute for Advanced Immunochemical Studies, iHuman Institute, School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China.,University of Chinese Academy of Sciences, Beijing 100101, China
| | - Chengyao Wu
- Shanghai Institute for Advanced Immunochemical Studies, iHuman Institute, School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Fangyu Wu
- State Key Laboratory of Medicinal Chemical Biology, Frontiers Science Center for Cell Response, College of Life Sciences, College of Pharmacy, Nankai University, Tianjin 300353, China
| | - Sudagar S Gurcha
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Natacha Veerapen
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Sarah M Batt
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Wei Zhao
- State Key Laboratory of Medicinal Chemical Biology, Frontiers Science Center for Cell Response, College of Life Sciences, College of Pharmacy, Nankai University, Tianjin 300353, China
| | - Ling Qin
- Shanghai Institute for Advanced Immunochemical Studies, iHuman Institute, School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Xiuna Yang
- Shanghai Institute for Advanced Immunochemical Studies, iHuman Institute, School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Manfu Wang
- Shanghai Institute for Advanced Immunochemical Studies, iHuman Institute, School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Yan Zhu
- Shanghai Institute for Advanced Immunochemical Studies, iHuman Institute, School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Bing Zhang
- Shanghai Institute for Advanced Immunochemical Studies, iHuman Institute, School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Lijun Bi
- National Laboratory of Biomacromolecules and Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, CAS, Beijing 100101, China
| | - Xian'en Zhang
- National Laboratory of Biomacromolecules and Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, CAS, Beijing 100101, China
| | - Haitao Yang
- Shanghai Institute for Advanced Immunochemical Studies, iHuman Institute, School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Luke W Guddat
- School of Chemistry and Molecular Biosciences, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Wenqing Xu
- Shanghai Institute for Advanced Immunochemical Studies, iHuman Institute, School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Quan Wang
- Shanghai Institute for Advanced Immunochemical Studies, iHuman Institute, School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China. .,National Laboratory of Biomacromolecules and Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, CAS, Beijing 100101, China
| | - Jun Li
- Shanghai Institute for Advanced Immunochemical Studies, iHuman Institute, School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China.
| | - Gurdyal S Besra
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.
| | - Zihe Rao
- Shanghai Institute for Advanced Immunochemical Studies, iHuman Institute, School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China. .,State Key Laboratory of Medicinal Chemical Biology, Frontiers Science Center for Cell Response, College of Life Sciences, College of Pharmacy, Nankai University, Tianjin 300353, China.,Laboratory of Structural Biology, Tsinghua University, Beijing 100084, China.,National Laboratory of Biomacromolecules and Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, CAS, Beijing 100101, China
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11
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Biosynthesis of Galactan in Mycobacterium tuberculosis as a Viable TB Drug Target? Antibiotics (Basel) 2020; 9:antibiotics9010020. [PMID: 31935842 PMCID: PMC7168186 DOI: 10.3390/antibiotics9010020] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 12/27/2019] [Accepted: 01/02/2020] [Indexed: 12/21/2022] Open
Abstract
While target-based drug design has proved successful in several therapeutic areas, this approach has not yet provided compelling outcomes in the field of antibacterial agents. This statement remains especially true for the development of novel therapeutic interventions against tuberculosis, an infectious disease that is among the top ten leading causes of death globally. Mycobacterial galactan is an important component of the protective cell wall core of the tuberculosis pathogen and it could provide a promising target for the design of new drugs. In this review, we summarize the current knowledge on galactan biosynthesis in Mycobacterium tuberculosis, including landmark findings that led to the discovery and understanding of three key enzymes in this pathway: UDP-galactose mutase, and galactofuranosyl transferases GlfT1 and GlfT2. Moreover, we recapitulate the efforts aimed at their inhibition. The predicted common transition states of the three enzymes provide the lucrative possibility of multitargeting in pharmaceutical development, a favourable property in the mitigation of drug resistance. We believe that a tight interplay between target-based computational approaches and experimental methods will result in the development of original inhibitors that could serve as the basis of a new generation of drugs against tuberculosis.
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Daffé M, Marrakchi H. Unraveling the Structure of the Mycobacterial Envelope. Microbiol Spectr 2019; 7:10.1128/microbiolspec.gpp3-0027-2018. [PMID: 31267927 PMCID: PMC10957186 DOI: 10.1128/microbiolspec.gpp3-0027-2018] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Indexed: 12/28/2022] Open
Abstract
The mycobacterial cell envelope consists of a typical plasma membrane of lipid and protein surrounded by a complex cell wall composed of carbohydrate and lipid. In pathogenic species, such as Mycobacterium tuberculosis, an outermost "capsule" layer surrounds the cell wall. This wall embraces a fundamental, covalently linked "cell-wall skeleton" composed of peptidoglycan, solidly attached to arabinogalactan, whose penta-saccharide termini are esterified by very-long-chain fatty acids (mycolic acids). These fatty acids form the inner leaflet of an outer membrane, called the mycomembrane, whose outer leaflet consists of a great variety of non-covalently linked lipids and glycolipids. The thickness of the mycomembrane, which is similar to that of the plasma membrane, is surprising in view of the length of mycoloyl residues, suggesting dedicated conformations of these fatty acids. Finally, a periplasmic space also exists in mycobacteria, between the plasma membrane and the peptidoglycan. This article provides a comprehensive overview of this biologically important and structurally unique mycobacterial cell compartment.
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Affiliation(s)
- Mamadou Daffé
- Institut de Pharmacologie et de Biologie Structurale, Université de Toulouse, CNRS, UPS, Department of Tuberculosis and Infection Biology, Toulouse, France
| | - Hedia Marrakchi
- Institut de Pharmacologie et de Biologie Structurale, Université de Toulouse, CNRS, UPS, Department of Tuberculosis and Infection Biology, Toulouse, France
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13
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Annaraj P D, Kadirvel P, Subramanian A, Anishetty S. Free enzyme dynamics of CmaA3 and CmaA2 cyclopropane mycolic acid synthases from Mycobacterium tuberculosis: Insights into residues with potential significance in cyclopropanation. J Mol Graph Model 2019; 91:61-71. [PMID: 31181453 DOI: 10.1016/j.jmgm.2019.05.016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2018] [Revised: 05/29/2019] [Accepted: 05/31/2019] [Indexed: 10/26/2022]
Abstract
Mycolic acids are long chain alpha-alkyl beta-hydroxy fatty acids that are major constituents of the cell wall of Mycobacterium tuberculosis. M. tuberculosis produces three main types of mycolic acids, alpha mycolic acids and keto and methoxy mycolic acids. Cycloproponated mycolic acids make the cell wall less permeable, contribute to antibiotic resistance and host immunomodulation and protect from injury. Cyclopropanation is catalyzed by enzymes of the Cyclopropane Mycolic Acid Synthase (CMAS) family. In the current study, we addressed two CMAS enzymes, proximal alpha cyclopropane mycolic acid synthase (PcaA/CmaA3) and keto cyclopropane Mycolic acid synthase (CmaA2). All-atom Molecular Dynamics (MD) simulations were performed for these enzymes for a timeframe of 100ns each (in triplicate), using GROMACS. Based on the PDB structures of apo and holo states of related CMAS enzymes, we generated a framework which helped us correlate active or inactive states of the enzymes to different conformations sampled by the enzymes during MD simulations. Dynamics suggested that the free or unbound enzymes have intrinsic memory and sample different states of catalysis even in the absence of the substrate/cofactor. Additionally, we find that F200, P201 and W204 may have functional significance. MD simulation of CmaA2 was performed with the objective of gaining insights into the putative role of a loop insert. Analysis showed that acidic residues of this loop possibly play an important role during the active state by forming salt bridges. The insights gained in this study can potentially be utilized for design of effective inhibitors against CMAS enzymes.
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Affiliation(s)
- David Annaraj P
- Centre for Biotechnology, Anna University, Chennai, 600 025, India
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14
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Biophysical characterization of mycobacterial model membranes and their interaction with rifabutin: Towards lipid-guided drug screening in tuberculosis. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2019; 1861:1213-1227. [PMID: 31002767 DOI: 10.1016/j.bbamem.2019.04.004] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Revised: 03/12/2019] [Accepted: 04/08/2019] [Indexed: 01/31/2023]
Abstract
Lipid structure critically dictates the molecular interactions of drugs with membranes influencing passive diffusion, drug partitioning and accumulation, thereby underpinning a lipid-composition specific interplay. Spurring selective passive drug diffusion and uptake through membranes is an obvious solution to combat growing antibiotic resistance with minimized toxicities. However, the spectrum of complex mycobacterial lipids and lack thereof of suitable membrane platforms limits the understanding of mechanisms underlying drug-membrane interactions in tuberculosis. Herein, we developed membrane scaffolds specific to mycobacterial outer membrane and demonstrate them as improvised research platforms for investigating anti-tubercular drug interactions. Combined spectroscopy and microscopy results reveal an enhanced partitioning of model drug Rifabutin in trehalose dimycolate-containing mycobacterial membrane systems. These effects are apportioned to specific changes in membrane structure, order and fluidity leading to enhanced drug interaction. These findings on the membrane biophysical consequences of drug interactions will offer valuable insights for guiding the design of more effective antibiotic drugs coupled with tuned toxicity profiles.
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15
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Faeza NMN, Jesse FFA, Hambali IU, Odhah MN, Umer M, Wessam MMS, Mohd-Azmi ML, Wahid AH. Responses of testosterone hormone concentration, semen quality, and its related pro-inflammatory cytokines in bucks following Corynebacterium pseudotuberculosis and its mycolic acid infection. Trop Anim Health Prod 2019; 51:1855-1866. [PMID: 30945156 DOI: 10.1007/s11250-019-01878-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Accepted: 03/22/2019] [Indexed: 11/30/2022]
Abstract
Corynebacterium pseudotuberculosis is the causative agent of caseous lymphadenitis, a debilitating chronic disease of sheep and goats. Little is known about the buck's reproductive pathophysiology with respect to inoculation with Corynebacterium pseudotuberculois and its immunogen mycolic acid extract. Therefore, this present study was designed to determine the concentration of testosterone hormone, pro-inflammatory cytokines, and semen quality of the experimental animals. A total of 12 bucks, divided into groups 1, 2, and 3 (Negative control group, Positive control group and Mycolic acid group respectively), were enrolled in this study. Following inoculation, all goats were observed for clinical responses and monitored for 60 days post-challenge and were then sacrificed. Blood samples were collected via the jugular once before inoculation and on a weekly basis post-challenge. Semen samples were collected 2 weeks post-challenge and prior to the sacrifice of the experimental animals. During the post inoculation period of 60 days, the concentration of testosterone hormone for group 2 was increased significantly (p < 0.05) in weeks 5, 6, and 9 but decreased in weeks 2 and 7 post inoculation. In group 3, the mean concentration of testosterone was increased significantly (p < 0.05) in weeks 5, 6, 7, and 9 post inoculation but decreased in week 2. The concentration of interleukin 6 (IL 6) in treated group 2 did not show any significant difference (p > 0.05) but increased significantly (p < 0.05) in week 2 post inoculation in group 3. For concentration of interleukin 1β (IL1β) in both treated groups 2 and 3 showed significant difference (p < 0.05) in weeks 2 and 3 post inoculation. The tumor necrosis factor-alpha (TNF-α) concentration in both treated groups 2 and 3 did not show any significant difference (p > 0.05) as compared to group 1. The concentration of interferon-γ (IFNγ) significantly increased (p < 0.05) for group 2 for weeks 2, 3, 4, and 5 where else for group 3 was not in significant difference (p > 0.05) compared to group 1. Both group 2 and group 3 showed a reduction in semen qualities as compared to group 1, but the severity was more intense in group 2 if compared to group 3. In conclusion, therefore, the present study concluded that the mycolic acid group revealed significant responses of testosterone hormone concentration, semen quality, and its related pro-inflammatory cytokines in bucks following infection but the severity lesser compared to Corynebacterium pseudotuberculosis group.
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Affiliation(s)
- N M N Faeza
- Department of Veterinary Clinical Studies, Faculty of Veterinary Medicine, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia.,Makmal BioSerasi, Universiti Kebangsaan Malaysia (UKM), 43600, Bangi, Malaysia
| | - F F A Jesse
- Department of Veterinary Clinical Studies, Faculty of Veterinary Medicine, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia. .,Institute of Tropical Agriculture and Food Security (ITAFoS), Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia. .,University Community Transformation Centre (UCTC), Universiti Putra Malaysia (UPM), 43400, Serdang, Selangor, Malaysia.
| | - I U Hambali
- Department of Veterinary Clinical Studies, Faculty of Veterinary Medicine, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia.,Department of Veterinary Public health and Preventive Medicine, University of Maiduguri, Maiduguri, 600233, Nigeria
| | - M N Odhah
- Department of Veterinary Clinical Studies, Faculty of Veterinary Medicine, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia
| | - M Umer
- Lasbela University of Agriculture Water and Marine Sciences Uthal Pakistan, Uthal, Pakistan
| | - M M S Wessam
- Department of Internal and Preventive Medicine, University of Basra, Basra State, Iraq
| | - M L Mohd-Azmi
- Department of Veterinary Pathology and Microbiology, Faculty of Veterinary Medicine, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia
| | - A H Wahid
- Department of Veterinary Clinical Studies, Faculty of Veterinary Medicine, Universiti Putra Malaysia, 43400, Serdang, Selangor, Malaysia
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16
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Ali OT, Mohammed MO, Gates PJ, Baird MS, Al Dulayymi JR. The synthesis of mycobacterial dimycoloyl diarabinoglycerol based on defined synthetic mycolic acids. Chem Phys Lipids 2019; 221:207-218. [PMID: 30639038 DOI: 10.1016/j.chemphyslip.2019.01.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 12/21/2018] [Accepted: 01/08/2019] [Indexed: 11/25/2022]
Abstract
Complex mixtures of natural dimycoloyl diarabinoglycerols isolated from mycobacteria have been shown to be both potent immune signalling agents and potentially valuable antigens in the serodiagnosis of mycobacterial infections. We now report the highly stereocontrolled synthesis of diacyl l-glycerol-(1'→1)-β-d-arabinofuranosyl-α-d-arabinofuranosides based on simple fatty acids and single defined synthetic mycolic acids. NMR analysis confirmed that the synthetic core was identical to that in natural mixtures.
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Affiliation(s)
- Omar T Ali
- School of Chemistry, Bangor University, Bangor, Gwynedd, LL57 2UW, UK
| | - Mohsin O Mohammed
- School of Chemistry, Bangor University, Bangor, Gwynedd, LL57 2UW, UK
| | - Paul J Gates
- School of Chemistry, Bristol University, Bristol, BS8 1TS, UK
| | - Mark S Baird
- School of Chemistry, Bangor University, Bangor, Gwynedd, LL57 2UW, UK.
| | - Juma'a R Al Dulayymi
- School of Chemistry, Bangor University, Bangor, Gwynedd, LL57 2UW, UK; School of Natural Sciences, Bangor University, Bangor, Gwynedd, LL57 2UW, UK
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Kolbe K, Veleti SK, Reiling N, Lindhorst TK. Lectins of Mycobacterium tuberculosis - rarely studied proteins. Beilstein J Org Chem 2019; 15:1-15. [PMID: 30680034 PMCID: PMC6334816 DOI: 10.3762/bjoc.15.1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2018] [Accepted: 11/29/2018] [Indexed: 12/19/2022] Open
Abstract
The importance of bacterial lectins for adhesion, pathogenicity, and biofilm formation is well established for many Gram-positive and Gram-negative bacteria. However, there is very little information available about lectins of the tuberculosis-causing bacterium, Mycobacterium tuberculosis (Mtb). In this paper we review previous studies on the carbohydrate-binding characteristics of mycobacteria and related Mtb proteins, discussing their potential relevance to Mtb infection and pathogenesis.
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Affiliation(s)
- Katharina Kolbe
- Tuberculosis Research Section, Laboratory of Clinical Immunology and Microbiology, National Institute of Allergy and Infectious Diseases, 33 North Drive, Bethesda, 20892, MD, United States
| | - Sri Kumar Veleti
- Tuberculosis Research Section, Laboratory of Clinical Immunology and Microbiology, National Institute of Allergy and Infectious Diseases, 33 North Drive, Bethesda, 20892, MD, United States
| | - Norbert Reiling
- Microbial Interface Biology, Research Center Borstel, Leibniz Lung Center, Parkallee 22, 23845 Borstel, Germany.,German Center for Infection Research (DZIF), Borstel Site, 23845 Borstel, Germany
| | - Thisbe K Lindhorst
- Otto Diels Institute of Organic Chemistry, Christiana Albertina University of Kiel, Otto-Hahn-Platz 3-4, 24118 Kiel, Germany
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The singular Corynebacterium glutamicum Emb arabinofuranosyltransferase polymerises the α(1 → 5) arabinan backbone in the early stages of cell wall arabinan biosynthesis. ACTA ACUST UNITED AC 2018; 2:38-53. [PMID: 30046665 PMCID: PMC6053596 DOI: 10.1016/j.tcsw.2018.06.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2018] [Revised: 06/14/2018] [Accepted: 06/15/2018] [Indexed: 11/20/2022]
Abstract
The arabinan-containing polysaccharides, arabinogalactan (AG) and lipoarabinomannan (LAM), are key cell wall components of the Corynebacterineae, which include Corynebacteria, Norcadia and Mycobacteria. Both AG and LAM contain elaborate arabinan domains composed of distinct structural motifs. Mycobacterial EmbA, EmbB and EmbC, collectively known as the Emb proteins, have been identified as arabinosyltransferases (ArafTs), which are targeted by the front-line anti-tubercular drug ethambutol. Previous studies have established that EmbA and EmbB play a role in the synthesis of the characteristic terminal hexa-arabinosuranosyl motif, whilst EmbC is involved exclusively in the biosynthesis of LAM. Herein, we have investigated the role of the singular Emb protein from Corynebacterium glutamicum through the detailed biochemical and chemical analysis of a double ΔaftAΔemb mutant, where the priming Cg-AftA protein, which generates the substrate for Cg-Emb has been deleted. Analysis of its cell wall revealed a complete absence of arabinose resulting in a truncated cell wall containing only a galactan backbone accompanied with complete loss of cell wall bound mycolates. In vitro cell-free assays using C. glutamicumΔaftA, C. glutamicumΔemb, C. glutamicumΔaftAΔemb and C. glutamicumΔaftBΔaftD and two synthetic acceptors, which mimick the arabinofuranose (Araf) “primed” galactan chain, demonstrated that Cg-Emb is able to transfer an Araf residue to the C5 of the Araf positioned on the synthetic acceptor(s). These results indicate that Cg-Emb acts as an α(1 → 5) ArafT and elongates the arabinan core during the early stages of arabinan biosynthesis in C. glutamicum.
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Two dd-Carboxypeptidases from Mycobacterium smegmatis Affect Cell Surface Properties through Regulation of Peptidoglycan Cross-Linking and Glycopeptidolipids. J Bacteriol 2018; 200:JB.00760-17. [PMID: 29735762 DOI: 10.1128/jb.00760-17] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2017] [Accepted: 04/25/2018] [Indexed: 11/20/2022] Open
Abstract
During the peptidoglycan (PG) maturation of mycobacteria, the glycan strands are interlinked by both 3-3 (between two meso-diaminopimelic acids [meso-DAPs]) and 4-3 cross-links (between d-Ala and meso-DAP), though there is a predominance (60 to 80%) of 3-3 cross-links. The dd-carboxypeptidases (dd-CPases) act on pentapeptides to generate tetrapeptides that are used by ld-transpeptidases as substrates to form 3-3 cross-links. Therefore, dd-CPases play a crucial role in mycobacterial PG cross-link formation. However, the physiology of dd-CPases in mycobacteria is relatively unexplored. In this study, we deleted two dd-CPase genes, msmeg_2433 and msmeg_2432, both individually and in combination, from Mycobacterium smegmatis mc2155. Though the single dd-CPase gene deletions had no significant impact on the mycobacterial physiology, many interesting functional alterations were observed in the double-deletion mutant, viz, a predominance in PG cross-link formation was shifted from 3-3 cross-links to 4-3, cell surface glycopeptidolipid (GPL) expression was reduced, and susceptibility to β-lactams and antitubercular agents was enhanced. Moreover, the survival rate of the double mutant within murine macrophages was higher than that of the parent. Interestingly, the complementation with any one of the dd-CPase genes could restore the wild-type phenotype. In a nutshell, we infer that the altered ratio of 4-3 to 3-3 PG cross-links might have influenced the expression of surface GPLs, colony morphology, biofilm formation, drug susceptibility, and subsistence of the cells within macrophages.IMPORTANCE The glycan strands in mycobacterial peptidoglycan (PG) are interlinked by both 3-3 and 4-3 cross-links. The dd-CPases generate tetrapeptides by acting on the pentapeptides, and ld-transpeptidases use tetrapeptides as substrates to form 3-3 cross-links. In this study, we showed that simultaneous deletions of two dd-CPases alter the nature of PG cross-linking from 3-3 cross-links to 4-3 cross-links. The deletions subsequently decrease the expression of glycopeptidolipids (significant surface lipid present in many nontuberculous mycobacteria, including Mycobacterium smegmatis) and affect other physiological parameters, like cell morphology, growth rate, biofilm formation, antibiotic susceptibility, and survival within murine macrophages. Thus, unraveling the physiology of dd-CPases might help us design antimycobacterial therapeutics in the future.
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Tsai YT, Salzman V, Cabruja M, Gago G, Gramajo H. Role of long-chain acyl-CoAs in the regulation of mycolic acid biosynthesis in mycobacteria. Open Biol 2018; 7:rsob.170087. [PMID: 28724694 PMCID: PMC5541348 DOI: 10.1098/rsob.170087] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Accepted: 06/26/2017] [Indexed: 12/16/2022] Open
Abstract
One of the dominant features of the biology of Mycobacterium tuberculosis, and other mycobacteria, is the mycobacterial cell envelope with its exceptional complex composition. Mycolic acids are major and very specific components of the cell envelope and play a key role in its architecture and impermeability. Biosynthesis of mycolic acid (MA) precursors requires two types of fatty acid synthases, FAS I and FAS II, which should work in concert in order to keep lipid homeostasis tightly regulated. Both FAS systems are regulated at their transcriptional level by specific regulatory proteins. FasR regulates components of the FAS I system, whereas MabR and FadR regulate components of the FAS II system. In this article, by constructing a tight mabR conditional mutant in Mycobacterium smegmatis mc2155, we demonstrated that sub-physiological levels of MabR lead to a downregulation of the fasII genes, inferring that this protein is a transcriptional activator of the FAS II system. In vivo labelling experiments and lipidomic studies carried out in the wild-type and the mabR conditional mutant demonstrated that under conditions of reduced levels of MabR, there is a clear inhibition of biosynthesis of MAs, with a concomitant change in their relative composition, and of other MA-containing molecules. These studies also demonstrated a change in the phospholipid composition of the membrane of the mutant strain, with a significant increase of phosphatidylinositol. Gel shift assays carried out with MabR and PfasII as a probe in the presence of different chain-length acyl-CoAs strongly suggest that molecules longer than C18 can be sensed by MabR to modulate its affinity for the operator sequences that it recognizes, and in that way switch on or off the MabR-dependent promoter. Finally, we demonstrated the direct role of MabR in the upregulation of the fasII operon genes after isoniazid treatment.
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Affiliation(s)
- Yi Ting Tsai
- Laboratory of Physiology and Genetics of Actinomycetes, Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Valentina Salzman
- Laboratory of Physiology and Genetics of Actinomycetes, Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Matías Cabruja
- Laboratory of Physiology and Genetics of Actinomycetes, Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Gabriela Gago
- Laboratory of Physiology and Genetics of Actinomycetes, Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
| | - Hugo Gramajo
- Laboratory of Physiology and Genetics of Actinomycetes, Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET), Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario, Rosario, Argentina
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Bhat ZS, Rather MA, Maqbool M, Lah HU, Yousuf SK, Ahmad Z. Cell wall: A versatile fountain of drug targets in Mycobacterium tuberculosis. Biomed Pharmacother 2017; 95:1520-1534. [PMID: 28946393 DOI: 10.1016/j.biopha.2017.09.036] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2017] [Revised: 09/07/2017] [Accepted: 09/10/2017] [Indexed: 12/18/2022] Open
Abstract
Tuberculosis is the leading infectious disease responsible for an estimated one and a half million human deaths each year around the globe. HIV-TB coinfection and rapid increase in the emergence of drug resistant forms of TB is a dangerous scenario. This underlines the urgent need for new drugs with novel mechanism of action. A plethora of literature exist that highlight the importance of enzymes involved in the biosynthesis of mycobacterial cell wall responsible for its survival, growth, permeability, virulence and resistance to antibiotics. Therefore, assembly of cell wall components is an attractive target for the development of chemotherapeutics against Mycobacterium tuberculosis. The aim of this review is to highlight novel sets of enzyme inhibitors that disrupt its cell wall biosynthetic pathway. These include the currently approved first and second line drugs, candidates in clinical trials and current structure activity guided endeavors of scientific community to identify new potent inhibitors with least cytotoxicity and better efficacy against emergence of drug resistance till date.
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Affiliation(s)
- Zubair Shanib Bhat
- Clinical Microbiology and PK/PD Division, Indian Institute of Integrative Medicine (IIIM), Campus, Sanat Nagar, Srinagar, Jammu & Kashmir 190005, India; Academy of Scientific and Innovative Research (AcSIR), CSIR- Indian Institute of Integrative Medicine (IIIM), Campus, Sanat Nagar, Srinagar, Jammu & Kashmir 190005, India.
| | - Muzafar Ahmad Rather
- Clinical Microbiology and PK/PD Division, Indian Institute of Integrative Medicine (IIIM), Campus, Sanat Nagar, Srinagar, Jammu & Kashmir 190005, India; Department of Biochemistry, University of Kashmir, Srinagar, Jammu & Kashmir 190006, India
| | - Mubashir Maqbool
- Clinical Microbiology and PK/PD Division, Indian Institute of Integrative Medicine (IIIM), Campus, Sanat Nagar, Srinagar, Jammu & Kashmir 190005, India; Department of Zoology, University of Kashmir, Srinagar, Jammu & Kashmir 190006, India
| | - Hafiz Ul Lah
- Medicinal Chemistry Division, Indian Institute of Integrative Medicine (IIIM), Campus, Sanat Nagar, Srinagar, Jammu & Kashmir 190005, India
| | - Syed Khalid Yousuf
- Academy of Scientific and Innovative Research (AcSIR), CSIR- Indian Institute of Integrative Medicine (IIIM), Campus, Sanat Nagar, Srinagar, Jammu & Kashmir 190005, India; Medicinal Chemistry Division, Indian Institute of Integrative Medicine (IIIM), Campus, Sanat Nagar, Srinagar, Jammu & Kashmir 190005, India
| | - Zahoor Ahmad
- Clinical Microbiology and PK/PD Division, Indian Institute of Integrative Medicine (IIIM), Campus, Sanat Nagar, Srinagar, Jammu & Kashmir 190005, India; Academy of Scientific and Innovative Research (AcSIR), CSIR- Indian Institute of Integrative Medicine (IIIM), Campus, Sanat Nagar, Srinagar, Jammu & Kashmir 190005, India.
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22
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Mohammed MO, Al Dulayymi JR, Baird MS. Preparation of the tri-arabino di-mycolate fragment of mycobacterial arabinogalactan from defined synthetic mycolic acids. Carbohydr Res 2017; 437:36-42. [DOI: 10.1016/j.carres.2016.11.006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Revised: 11/07/2016] [Accepted: 11/07/2016] [Indexed: 11/30/2022]
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Abstract
Mycobacterium tuberculosis (Mtb), the etiological agent of tuberculosis (TB), is recognized as a global health emergency as promoted by the World Health Organization. Over 1 million deaths per year, along with the emergence of multi- and extensively-drug resistant strains of Mtb, have triggered intensive research into the pathogenicity and biochemistry of this microorganism, guiding the development of anti-TB chemotherapeutic agents. The essential mycobacterial cell wall, sharing some common features with all bacteria, represents an apparent ‘Achilles heel’ that has been targeted by TB chemotherapy since the advent of TB treatment. This complex structure composed of three distinct layers, peptidoglycan, arabinogalactan and mycolic acids, is vital in supporting cell growth, virulence and providing a barrier to antibiotics. The fundamental nature of cell wall synthesis and assembly has rendered the mycobacterial cell wall as the most widely exploited target of anti-TB drugs. This review provides an overview of the biosynthesis of the prominent cell wall components, highlighting the inhibitory mechanisms of existing clinical drugs and illustrating the potential of other unexploited enzymes as future drug targets.
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Abstract
The cell wall of Mycobacterium tuberculosis is unique in that it differs significantly from those of both Gram-negative and Gram-positive bacteria. The thick, carbohydrate- and lipid-rich cell wall with distinct lipoglycans enables mycobacteria to survive under hostile conditions such as shortage of nutrients and antimicrobial exposure. The key features of this highly complex cell wall are the mycolyl-arabinogalactan-peptidoglycan (mAGP)-based and phosphatidyl-myo-inositol-based macromolecular structures, with the latter possessing potent immunomodulatory properties. These structures are crucial for the growth, viability, and virulence of M. tuberculosis and therefore are often the targets of effective chemotherapeutic agents against tuberculosis. Over the past decade, sophisticated genomic and molecular tools have advanced our understanding of the primary structure and biosynthesis of these macromolecules. The availability of the full genome sequences of various mycobacterial species, including M. tuberculosis, Mycobacterium marinum, and Mycobacterium bovis BCG, have greatly facilitated the identification of large numbers of drug targets and antigens specific to tuberculosis. Techniques to manipulate mycobacteria have also improved extensively; the conditional expression-specialized transduction essentiality test (CESTET) is currently used to determine the essentiality of individual genes. Finally, various biosynthetic assays using either purified proteins or synthetic cell wall acceptors have been developed to study enzyme function. This article focuses on the recent advances in determining the structural details and biosynthesis of arabinogalactan, lipoarabinomannan, and related glycoconjugates.
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Affiliation(s)
- Monika Jankute
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom;
| | - Jonathan A.G. Cox
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom;
| | - James Harrison
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom;
| | - Gurdyal S. Besra
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom;
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GtrA Protein Rv3789 Is Required for Arabinosylation of Arabinogalactan in Mycobacterium tuberculosis. J Bacteriol 2015; 197:3686-97. [PMID: 26369580 DOI: 10.1128/jb.00628-15] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Accepted: 09/07/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Mycobacterium tuberculosis possesses a thick and highly hydrophobic cell wall principally composed of a mycolyl-arabinogalactan-peptidoglycan complex, which is critical for survival and virulence. DprE1 is a well-characterized component of decaprenyl-phospho-ribose epimerase, which produces decaprenyl-phospho-arabinose (DPA) for the biosynthesis of mycobacterial arabinans. Upstream of dprE1 lies rv3789, which encodes a short transmembrane protein of the GtrA family, whose members are often involved in the synthesis of cell surface polysaccharides. We demonstrate that rv3789 and dprE1 are cotranscribed from a common transcription start site situated 64 bp upstream of rv3789. Topology mapping revealed four transmembrane domains in Rv3789 and a cytoplasmic C terminus consistent with structural models built using analysis of sequence coevolution. To investigate its role, we generated an unmarked rv3789 deletion mutant in M. tuberculosis. The mutant was characterized by impaired growth and abnormal cell morphology, since the cells were shorter and more swollen than wild-type cells. This phenotype likely stems from the decreased incorporation of arabinan into arabinogalactan and was accompanied by an accumulation of DPA. A role for Rv3789 in arabinan biosynthesis was further supported by its interaction with the priming arabinosyltransferase AftA, as demonstrated by a two-hybrid approach. Taken together, the data suggest that Rv3789 does not act as a DPA flippase but, rather, recruits AftA for arabinogalactan biosynthesis. IMPORTANCE Upstream of the essential dprE1 gene, encoding a key enzyme of the decaprenyl phospho-arabinose (DPA) pathway, lies rv3789, coding for a short transmembrane protein of unknown function. In this study, we demonstrated that rv3789 and dprE1 are cotranscribed from a common transcription start site located 64 bp upstream of rv3789 in M. tuberculosis. Furthermore, the deletion of rv3789 led to a reduction in arabinan content and to an accumulation of DPA, confirming that Rv3789 plays a role in arabinan biosynthesis. Topology mapping, structural modeling, and protein interaction studies suggest that Rv3789 acts as an anchor protein recruiting AftA, the first arabinosyl transferase. This investigation provides deeper insight into the mechanism of arabinan biosynthesis in mycobacteria.
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Jankute M, Byng CV, Alderwick LJ, Besra GS. Elucidation of a protein-protein interaction network involved in Corynebacterium glutamicum cell wall biosynthesis as determined by bacterial two-hybrid analysis. Glycoconj J 2015; 31:475-83. [PMID: 25117516 PMCID: PMC4213368 DOI: 10.1007/s10719-014-9549-3] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Mycobacterium species have a highly complex and unique cell wall that consists of a large macromolecular structure termed the mycolyl-arabinogalactan-peptidoglycan (mAGP) complex. This complex is essential for growth, survival and virulence of the human pathogen Mycobacterium tuberculosis, and is the target of several anti-tubercular drugs. The closely related species Corynebacterium glutamicum has proven useful in the study of orthologous M. tuberculosis genes and proteins involved in mAGP synthesis. This study examines the construction of a protein-protein interaction network for the major cell wall component arabinogalactan in C. glutamicum based on the use of a bacterial two-hybrid system. We have identified twenty-four putative homotypic and heterotypic protein interactions in vivo. Our results demonstrate an association between glycosyltransferases, GlfT1 and AftB, and interaction between the sub-units of decaprenylphosphoribose epimerase, DprE1 and DprE2. These analyses have also shown that AftB interacts with AftA, which catalyzes the addition of the first three arabinose units onto the galactan chain. Both AftA and AftB associate with other arabinofuranosyltransferases, including Emb and AftC, that elongate and branch the arabinan domain. Moreover, a number of proteins involved in arabinogalactan biosynthesis were shown to form dimers or multimers. These findings provide a useful recourse for understanding the biosynthesis and function of the mycobacterial cell wall, as well as providing new therapeutic targets.
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Affiliation(s)
- Monika Jankute
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
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Eppe G, El Bkassiny S, Vincent SP. Galactofuranose Biosynthesis: Discovery, Mechanisms and Therapeutic Relevance. CARBOHYDRATES IN DRUG DESIGN AND DISCOVERY 2015. [DOI: 10.1039/9781849739993-00209] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Galactofuranose, the atypical and thermodynamically disfavored form of d-galactose, has in reality a very old history in chemistry and biochemistry. The purpose of this book chapter is to give an overview on the fundamental aspects of the galactofuranose biosynthesis, from the biological occurrence to the search of inhibitors.
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Affiliation(s)
- Guillaume Eppe
- University of Namur, Département de Chimie, Laboratoire de Chimie Bio-Organique rue de Bruxelles 61 B-5000 Namur Belgium
| | - Sandy El Bkassiny
- University of Namur, Département de Chimie, Laboratoire de Chimie Bio-Organique rue de Bruxelles 61 B-5000 Namur Belgium
| | - Stéphane P. Vincent
- University of Namur, Département de Chimie, Laboratoire de Chimie Bio-Organique rue de Bruxelles 61 B-5000 Namur Belgium
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Angala SK, Belardinelli JM, Huc-Claustre E, Wheat WH, Jackson M. The cell envelope glycoconjugates of Mycobacterium tuberculosis. Crit Rev Biochem Mol Biol 2014; 49:361-99. [PMID: 24915502 PMCID: PMC4436706 DOI: 10.3109/10409238.2014.925420] [Citation(s) in RCA: 107] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Tuberculosis (TB) remains the second most common cause of death due to a single infectious agent. The cell envelope of Mycobacterium tuberculosis (Mtb), the causative agent of the disease in humans, is a source of unique glycoconjugates and the most distinctive feature of the biology of this organism. It is the basis of much of Mtb pathogenesis and one of the major causes of its intrinsic resistance to chemotherapeutic agents. At the same time, the unique structures of Mtb cell envelope glycoconjugates, their antigenicity and essentiality for mycobacterial growth provide opportunities for drug, vaccine, diagnostic and biomarker development, as clearly illustrated by recent advances in all of these translational aspects. This review focuses on our current understanding of the structure and biogenesis of Mtb glycoconjugates with particular emphasis on one of the most intriguing and least understood aspect of the physiology of mycobacteria: the translocation of these complex macromolecules across the different layers of the cell envelope. It further reviews the rather impressive progress made in the last 10 years in the discovery and development of novel inhibitors targeting their biogenesis.
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Affiliation(s)
- Shiva Kumar Angala
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University , Fort Collins, CO , USA
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Abstract
Mycobacteria are surrounded by a complex multilayered envelope and elongate at the poles. The principles that organize the coordinated addition of chemically diverse cell wall layers during polar extension remain unclear. We show that enzymes mediating the terminal cytosolic steps of peptidoglycan, arabinogalactan, and mycolic acid synthesis colocalize at sites of cell growth or division. The tropomyosin-like protein, DivIVA, is targeted to the negative curvature of the pole, is enriched at the growing end, and determines cell shape from this site. In contrast, cell wall synthetic complexes are concentrated at a distinct subpolar location. When viewed at subdiffraction resolution, new peptidoglycan is deposited at this subpolar site, and inert cell wall covers the DivIVA-marked tip. The differentiation between polar tip and cell wall synthetic complexes is also apparent at the biochemical level. Enzymes that generate mycolate precursors interact with DivIVA, but the final condensation of mycolic acids occurs in a distinct protein complex at the site of nascent cell wall addition. We propose an ultrastructural model of mycobacterial polar growth where new cell wall is added in an annular zone below the cell tip. This model may be broadly applicable to other bacterial and fungal organisms that grow via polar extension.
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Backus KM, Dolan MA, Barry CS, Joe M, McPhie P, Boshoff HIM, Lowary TL, Davis BG, Barry CE. The three Mycobacterium tuberculosis antigen 85 isoforms have unique substrates and activities determined by non-active site regions. J Biol Chem 2014; 289:25041-53. [PMID: 25028517 DOI: 10.1074/jbc.m114.581579] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The three isoforms of antigen 85 (A, B, and C) are the most abundant secreted mycobacterial proteins and catalyze transesterification reactions that synthesize mycolated arabinogalactan, trehalose monomycolate (TMM), and trehalose dimycolate (TDM), important constituents of the outermost layer of the cellular envelope of Mycobacterium tuberculosis. These three enzymes are nearly identical at the active site and have therefore been postulated to exist to evade host immunity. Distal to the active site is a second putative carbohydrate-binding site of lower homology. Mutagenesis of the three isoforms at this second site affected both substrate selectivity and overall catalytic activity in vitro. Using synthetic and natural substrates, we show that these three enzymes exhibit unique selectivity; antigen 85A more efficiently mycolates TMM to form TDM, whereas C (and to a lesser extent B) has a higher rate of activity using free trehalose to form TMM. This difference in substrate selectivity extends to the hexasaccharide fragment of cell wall arabinan. Mutation of secondary site residues from the most active isoform (C) into those present in A or B partially interconverts this substrate selectivity. These experiments in combination with molecular dynamics simulations reveal that differences in the N-terminal helix α9, the adjacent Pro(216)-Phe(228) loop, and helix α5 are the likely cause of changes in activity and substrate selectivity. These differences explain the existence of three isoforms and will allow for future work in developing inhibitors.
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Affiliation(s)
- Keriann M Backus
- From the Tuberculosis Research Section, Laboratory of Clinical Infectious Diseases, and the Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Oxford OX1 3TA, United Kingdom
| | - Michael A Dolan
- the Bioinformatics and Computational Biosciences Branch, NIAID, National Institutes of Health, Bethesda, Maryland 20892
| | - Conor S Barry
- the Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Oxford OX1 3TA, United Kingdom
| | - Maju Joe
- the Alberta Glycomics Centre and Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada, and
| | - Peter McPhie
- the Laboratory of Biochemistry and Genetics, NIDDK, National Institutes of Health, Bethesda, Maryland 20892
| | - Helena I M Boshoff
- From the Tuberculosis Research Section, Laboratory of Clinical Infectious Diseases, and
| | - Todd L Lowary
- the Alberta Glycomics Centre and Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada, and
| | - Benjamin G Davis
- the Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Oxford OX1 3TA, United Kingdom,
| | - Clifton E Barry
- From the Tuberculosis Research Section, Laboratory of Clinical Infectious Diseases, and
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Mycolic acids: structures, biosynthesis, and beyond. ACTA ACUST UNITED AC 2013; 21:67-85. [PMID: 24374164 DOI: 10.1016/j.chembiol.2013.11.011] [Citation(s) in RCA: 367] [Impact Index Per Article: 33.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Revised: 11/04/2013] [Accepted: 11/27/2013] [Indexed: 11/24/2022]
Abstract
Mycolic acids are major and specific lipid components of the mycobacterial cell envelope and are essential for the survival of members of the genus Mycobacterium that contains the causative agents of both tuberculosis and leprosy. In the alarming context of the emergence of multidrug-resistant, extremely drug-resistant, and totally drug-resistant tuberculosis, understanding the biosynthesis of these critical determinants of the mycobacterial physiology is an important goal to achieve, because it may open an avenue for the development of novel antimycobacterial agents. This review focuses on the chemistry, structures, and known inhibitors of mycolic acids and describes progress in deciphering the mycolic acid biosynthetic pathway. The functional and key biological roles of these molecules are also discussed, providing a historical perspective in this dynamic area.
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Free mycolic acid accumulation in the cell wall of the mce1 operon mutant strain of Mycobacterium tuberculosis. J Microbiol 2013; 51:619-26. [PMID: 24037657 DOI: 10.1007/s12275-013-3092-y] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2013] [Accepted: 05/15/2013] [Indexed: 01/29/2023]
Abstract
The lipid-rich cell wall of Mycobacterium tuberculosis, the agent of tuberculosis, serves as an effective barrier against many chemotherapeutic agents and toxic host cell effector molecules, and it may contribute to the mechanism of persistence. Mycobacterium tuberculosis strains mutated in a 13-gene operon called mce1, which encodes a putative ABC lipid transporter, induce aberrant granulomatous response in mouse lungs. Because of the postulated role of the mce1 operon in lipid importation, we compared the cell wall lipid composition of wild type and mce1 operon mutant M. tuberculosis H37Rv strains. High resolution mass spectrometric analyses of the mce1 mutant lipid extracts showed unbound mycolic acids to accumulate in the cell wall. Quantitative analysis revealed a 10.7 fold greater amount of free mycolates in the mutant compared to that of the wild type strain. The free mycolates were comprised of alpha, methoxy and keto mycolates in the ratio 1:0.9:0.6, respectively. Since the mce1 operon is regulated in vivo, the free mycolates that accumulate during infection may serve as a barrier for M. tuberculosis against toxic products and contribute to the pathogen's persistence.
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Jankute M, Grover S, Rana AK, Besra GS. Arabinogalactan and lipoarabinomannan biosynthesis: structure, biogenesis and their potential as drug targets. Future Microbiol 2012; 7:129-47. [PMID: 22191451 DOI: 10.2217/fmb.11.123] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Mycobacterium tuberculosis, the etiological agent of TB, remains the leading cause of mortality from a single infectious organism. The persistence of this human pathogen is associated with its distinctive lipid-rich cell wall structure that is highly impermeable to hydrophilic chemical drugs. This highly complex and unique structure is crucial for the growth, viability and virulence of M. tuberculosis, thus representing an attractive target for vaccine and drug development. It contains a large macromolecular structure known as the mycolyl-arabinogalactan-peptidoglycan complex, as well as phosphatidyl-myo-inositol derived glycolipids with potent immunomodulatory activity, notably lipomannan and lipoarabinomannan. These cell wall components are often the targets of effective chemotherapeutic agents against TB, such as ethambutol. This review focuses on the structural details and biosynthetic pathways of both arabinogalactan and lipoarabinomannan, as well as the effects of potent drugs on these important (lipo)polysaccharides.
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Affiliation(s)
- Monika Jankute
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
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Maity K, Bajaj P, Surolia N, Surolia A, Suguna K. Insights into the Substrate Specificity of a Thioesterase Rv0098 ofMycobacterium Tuberculosisthrough X-ray Crystallographic and Molecular Dynamics Studies. J Biomol Struct Dyn 2012; 29:973-83. [DOI: 10.1080/07391102.2012.10507417] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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Mishra AK, Driessen NN, Appelmelk BJ, Besra GS. Lipoarabinomannan and related glycoconjugates: structure, biogenesis and role in Mycobacterium tuberculosis physiology and host-pathogen interaction. FEMS Microbiol Rev 2011; 35:1126-57. [PMID: 21521247 PMCID: PMC3229680 DOI: 10.1111/j.1574-6976.2011.00276.x] [Citation(s) in RCA: 207] [Impact Index Per Article: 15.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Approximately one third of the world's population is infected with Mycobacterium tuberculosis, the causative agent of tuberculosis. This bacterium has an unusual lipid-rich cell wall containing a vast repertoire of antigens, providing a hydrophobic impermeable barrier against chemical drugs, thus representing an attractive target for vaccine and drug development. Apart from the mycolyl–arabinogalactan–peptidoglycan complex, mycobacteria possess several immunomodulatory constituents, notably lipomannan and lipoarabinomannan. The availability of whole-genome sequences of M. tuberculosis and related bacilli over the past decade has led to the identification and functional characterization of various enzymes and the potential drug targets involved in the biosynthesis of these glycoconjugates. Both lipomannan and lipoarabinomannan possess highly variable chemical structures, which interact with different receptors of the immune system during host–pathogen interactions, such as Toll-like receptors-2 and C-type lectins. Recently, the availability of mutants defective in the synthesis of these glycoconjugates in mycobacteria and the closely related bacterium, Corynebacterium glutamicum, has paved the way for host–pathogen interaction studies, as well as, providing attenuated strains of mycobacteria for the development of new vaccine candidates. This review provides a comprehensive account of the structure, biosynthesis and immunomodulatory properties of these important glycoconjugates.
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Affiliation(s)
- Arun K Mishra
- School of Biosciences, University of Birmingham, Edgbaston, UK
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Bhamidi S, Scherman MS, Jones V, Crick DC, Belisle JT, Brennan PJ, McNeil MR. Detailed structural and quantitative analysis reveals the spatial organization of the cell walls of in vivo grown Mycobacterium leprae and in vitro grown Mycobacterium tuberculosis. J Biol Chem 2011; 286:23168-77. [PMID: 21555513 DOI: 10.1074/jbc.m110.210534] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The cell wall of mycobacteria consists of an outer membrane, analogous to that of gram-negative bacteria, attached to the peptidoglycan (PG) via a connecting polysaccharide arabinogalactan (AG). Although the primary structure of these components is fairly well deciphered, issues such as the coverage of the PG layer by covalently attached mycolates in the outer membrane and the spatial details of the mycolic acid attachment to the arabinan have remained unknown. It is also not understood how these components work together to lead to the classical acid-fast staining of mycobacteria. Because the majority of Mycobacterium tuberculosis bacteria in established experimental animal infections are acid-fast negative, clearly cell wall changes are occurring. To address both the spatial properties of mycobacterial cell walls and to begin to study the differences between bacteria grown in animals and cultures, the cell walls of Mycobacterium leprae grown in armadillos was characterized and compared with that of M. tuberculosis grown in culture. Most fundamentally, it was determined that the cell wall of M. leprae contained significantly more mycolic acids attached to PG than that of in vitro grown M. tuberculosis (mycolate:PG ratios of 21:10 versus 16:10, respectively). In keeping with this difference, more arabinogalactan (AG) molecules, linking the mycolic acids to PG, were found. Differences in the structures of the AG were also found; the AG of M. leprae is smaller than that of M. tuberculosis, although the same basic structural motifs are retained.
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Affiliation(s)
- Suresh Bhamidi
- Department of Microbiology, Immunology, and Pathology, Colorado State University, Fort Collins, Colorado 80523, USA
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Mishra AK, Krumbach K, Rittmann D, Appelmelk B, Pathak V, Pathak AK, Nigou J, Geurtsen J, Eggeling L, Besra GS. Lipoarabinomannan biosynthesis in Corynebacterineae: the interplay of two α(1→2)-mannopyranosyltransferases MptC and MptD in mannan branching. Mol Microbiol 2011; 80:1241-59. [PMID: 21435038 PMCID: PMC3123699 DOI: 10.1111/j.1365-2958.2011.07640.x] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Lipomannan (LM) and lipoarabinomannan (LAM) are key Corynebacterineae glycoconjugates that are integral components of the mycobacterial cell wall, and are potent immunomodulators during infection. LAM is a complex heteropolysaccharide synthesized by an array of essential glycosyltransferase family C (GT-C) members, which represent potential drug targets. Herein, we have identified and characterized two open reading frames from Corynebacterium glutamicum that encode for putative GT-Cs. Deletion of NCgl2100 and NCgl2097 in C. glutamicum demonstrated their role in the biosynthesis of the branching α(1→2)-Manp residues found in LM and LAM. In addition, utilizing a chemically defined nonasaccharide acceptor, azidoethyl 6-O-benzyl-α-D-mannopyranosyl-(1→6)-[α-D-mannopyranosyl-(1→6)]7-D-mannopyranoside, and the glycosyl donor C50-polyprenol-phosphate-[14C]-mannose with membranes prepared from different C. glutamicum mutant strains, we have shown that both NCgl2100 and NCgl2097 encode for novel α(1→2)-mannopyranosyltransferases, which we have termed MptC and MptD respectively. Complementation studies and in vitro assays also identified Rv2181 as a homologue of Cg-MptC in Mycobacterium tuberculosis. Finally, we investigated the ability of LM and LAM from C. glutamicum, and C. glutamicumΔmptC and C. glutamicumΔmptD mutants, to activate Toll-like receptor 2. Overall, our study enhances our understanding of complex lipoglycan biosynthesis in Corynebacterineae and sheds further light on the structural and functional relationship of these classes of polysaccharides.
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Affiliation(s)
- Arun K Mishra
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
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Marriner GA, Nayyar A, Uh E, Wong SY, Mukherjee T, Via LE, Carroll M, Edwards RL, Gruber TD, Choi I, Lee J, Arora K, England KD, Boshoff HIM, Barry CE. The Medicinal Chemistry of Tuberculosis Chemotherapy. TOPICS IN MEDICINAL CHEMISTRY 2011. [DOI: 10.1007/7355_2011_13] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/12/2023]
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Molle V, Gulten G, Vilchèze C, Veyron-Churlet R, Zanella-Cléon I, Sacchettini JC, Jacobs Jr WR, Kremer L. Phosphorylation of InhA inhibits mycolic acid biosynthesis and growth of Mycobacterium tuberculosis. Mol Microbiol 2010; 78:1591-605. [DOI: 10.1111/j.1365-2958.2010.07446.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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Alderwick LJ, Lloyd GS, Lloyd AJ, Lovering AL, Eggeling L, Besra GS. Biochemical characterization of the Mycobacterium tuberculosis phosphoribosyl-1-pyrophosphate synthetase. Glycobiology 2010; 21:410-25. [PMID: 21045009 PMCID: PMC3055594 DOI: 10.1093/glycob/cwq173] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Mycobacterium tuberculosis arabinogalactan (AG) is an essential cell wall component. It provides a molecular framework serving to connect peptidoglycan to the outer mycolic acid layer. The biosynthesis of the arabinan domains of AG and lipoarabinomannan (LAM) occurs via a combination of membrane bound arabinofuranosyltransferases, all of which utilize decaprenol-1-monophosphorabinose as a substrate. The source of arabinose ultimately destined for deposition into cell wall AG or LAM originates exclusively from phosphoribosyl-1-pyrophosphate (pRpp), a central metabolite which is also required for other essential metabolic processes, such as de novo purine and pyrimidine biosyntheses. In M. tuberculosis, a single pRpp synthetase enzyme (Mt-PrsA) is solely responsible for the generation of pRpp, by catalyzing the transfer of pyrophosphate from ATP to the C1 hydroxyl position of ribose-5-phosphate. Here, we report a detailed biochemical and biophysical study of Mt-PrsA, which exhibits the most rapid enzyme kinetics reported for a pRpp synthetase.
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Affiliation(s)
- Luke J Alderwick
- School of Biosciences, University of Birmingham, Edgbaston Park Road, Birmingham B15 2TT, UK
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Singh G, Singh G, Jadeja D, Kaur J. Lipid hydrolizing enzymes in virulence: Mycobacterium tuberculosis as a model system. Crit Rev Microbiol 2010; 36:259-69. [PMID: 20500016 DOI: 10.3109/1040841x.2010.482923] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
This review is focused on the virulent traits of lipolytic enzymes from bacteria with special emphasis on Mycobacterium tuberculosis. In vivo, triacylglycerols in the form of inclusion bodies are present in tubercle bacilli in the lungs. This pathogenic bacterium possesses a lipase gene (Lip) family, which is expressed and differentially regulated under a variety of in vitro conditions. Not much research work has been carried out on these lipolytic enzymes. A better understanding of lipolytic enzymes in mycobacteria would lead to develop new strategies for tuberculosis treatment. The present review highlights the recent work done in the field of mycobacterium lipolytic enzymes and their involvement in the virulence and pathogenicity.
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Affiliation(s)
- Gurdyal Singh
- Department of Biotechnology, Panjab University, Chandigarh-160014, India
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Zhang J, Amin AG, Hölemann A, Seeberger PH, Chatterjee D. Development of a plate-based scintillation proximity assay for the mycobacterial AftB enzyme involved in cell wall arabinan biosynthesis. Bioorg Med Chem 2010; 18:7121-31. [PMID: 20800502 DOI: 10.1016/j.bmc.2010.07.040] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2010] [Revised: 07/13/2010] [Accepted: 07/16/2010] [Indexed: 01/03/2023]
Abstract
A number of mycobacterial arabinosyltransferases, such as the Emb proteins, AftA, AftB, AftC, and AftD have been characterized and implicated to be involved in the cell wall arabinan assembly. These arabinosyltransferases are essential for the viability of the organism and are logically valid targets for developing new anti-tuberculosis agents. For instance, Ethambutol, a first line anti-tuberculosis drug, targets the Emb proteins involved in the formation of the arabinan of cell wall arabinogalactan. Among these arabinosyltransferases, the terminal β-(1→2) arabinosyltransferase activity has been associated with AftB. The predicted topology of AftB in Mycobacterium tuberculosis has 10 N terminal transmembrane domains and a C terminal hydrophilic domain similar to the Emb proteins. It has a conserved GT-C motif and is difficult to express. In a cell free assay, synthetic disaccharide, α-D-Araf-(1→5)-α-D-Araf-octyl, has been used as a substrate to explore the function of AftB. In our work, the disaccharide was synthesized in its pentenylated and biotinylated form, and the enzymatic product formed was identified as the β-(1→2) arabinofuranose adduct. When synthetic tri- and tetra-saccharides were used as substrates, a mixture of products containing both β-(1→2) and α-(1→5) linkages were formed. Therefore, the biotinylated disaccharide was selected to develop a scintillation proximity assay.
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Affiliation(s)
- Jian Zhang
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523, USA.
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Zhang Z, Pen Y, Edyvean RG, Banwart SA, Dalgliesh RM, Geoghegan M. Adhesive and conformational behaviour of mycolic acid monolayers. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1798:1829-39. [DOI: 10.1016/j.bbamem.2010.05.024] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2010] [Revised: 05/25/2010] [Accepted: 05/28/2010] [Indexed: 10/19/2022]
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Mihoub M, Aloui A, EL May A, Sethom MM, Ben Ammar A, Jaafoura MH, Kacem R, Landoulsi A. Effects of garlic extract on cell wall of Corynebacterium glutamicum. ANN MICROBIOL 2010. [DOI: 10.1007/s13213-010-0103-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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Mederos LM, Montoro EH, Bernabéu A, Linares C, Valero-Guillén PL. Structural studies of cord factors from Mycobacterium simiae related to the capacity for tumour necrosis factor alpha (α-TNF) induction. MICROBIOLOGY-SGM 2010; 156:3744-3753. [PMID: 20688816 DOI: 10.1099/mic.0.042077-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The structure of cord factor was studied in several strains of Mycobacterium simiae, including 'habana' TMC 5135, considered as highly immunogenic in experimental tuberculosis and leprosy. The mycolic acids liberated from cord factor were identified in all cases as α'-, α- and keto-mycolates. According to the general NMR and MS data, α'-mycolates were mono-unsaturated and contained from 64 to 68 carbon atoms, whereas α-mycolates mainly presented two 2,3-disubstituted cyclopropane rings and a chain length of 80-91 carbon atoms; keto-mycolates mostly contained one cyclopropane ring and 85-91 carbon atoms. Taking into account the (1)H-NMR results, strains varied in the ratio of the different mycolates, and the high levels of keto-mycolates found in the cord factors of TMC 5135 and ATCC 25275(T) stood out. Notably, MS revealed that the odd carbon number series of α-mycolates (C87-C89) predominated in the cord factor of TMC 5135, in contrast to the remaining studied strains, in which the even (C84-C86) and odd carbon number series appeared more equal. The fine structural differences detected among the cord factors studied did not seem to be relevant to the general capacity of these molecules to induce the secretion of tumour necrosis factor alpha, as the cord factors from several strains of M. simiae (TMC 5135, IPK-342 and ATCC 25275(T)) induced similar amounts of this cytokine in RAW 264.7 cells.
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Affiliation(s)
- Lilian M Mederos
- Laboratorio Nacional de Referencia e Investigaciones en Tuberculosis y Micobacterias, Centro Colaborador OPS/OMS, Instituto de Medicina Tropical Pedro Kourí (IPK), La Habana, Cuba
| | - Ernesto H Montoro
- Laboratorio Nacional de Referencia e Investigaciones en Tuberculosis y Micobacterias, Centro Colaborador OPS/OMS, Instituto de Medicina Tropical Pedro Kourí (IPK), La Habana, Cuba
| | - Antonia Bernabéu
- Sección de Cultivo de Tejidos, Servicio de Apoyo a la Investigación, Campus Universitario de Espinardo, Universidad de Murcia, Murcia, Spain
| | - Carlos Linares
- Departamento de Genética y Microbiología, Facultad de Medicina y Odontología, Campus Universitario de Espinardo, Universidad de Murcia, Murcia, Spain
| | - Pedro L Valero-Guillén
- Departamento de Genética y Microbiología, Facultad de Medicina y Odontología, Campus Universitario de Espinardo, Universidad de Murcia, Murcia, Spain
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