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Shimokawa M, Ishiwata A, Kashima T, Nakashima C, Li J, Fukushima R, Sawai N, Nakamori M, Tanaka Y, Kudo A, Morikami S, Iwanaga N, Akai G, Shimizu N, Arakawa T, Yamada C, Kitahara K, Tanaka K, Ito Y, Fushinobu S, Fujita K. Identification and characterization of endo-α-, exo-α-, and exo-β-D-arabinofuranosidases degrading lipoarabinomannan and arabinogalactan of mycobacteria. Nat Commun 2023; 14:5803. [PMID: 37726269 PMCID: PMC10509167 DOI: 10.1038/s41467-023-41431-2] [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: 04/05/2023] [Accepted: 08/29/2023] [Indexed: 09/21/2023] Open
Abstract
The cell walls of pathogenic and acidophilic bacteria, such as Mycobacterium tuberculosis and Mycobacterium leprae, contain lipoarabinomannan and arabinogalactan. These components are composed of D-arabinose, the enantiomer of the typical L-arabinose found in plants. The unique glycan structures of mycobacteria contribute to their ability to evade mammalian immune responses. In this study, we identified four enzymes (two GH183 endo-D-arabinanases, GH172 exo-α-D-arabinofuranosidase, and GH116 exo-β-D-arabinofuranosidase) from Microbacterium arabinogalactanolyticum. These enzymes completely degraded the complex D-arabinan core structure of lipoarabinomannan and arabinogalactan in a concerted manner. Furthermore, through biochemical characterization using synthetic substrates and X-ray crystallography, we elucidated the mechanisms of substrate recognition and anomer-retaining hydrolysis for the α- and β-D-arabinofuranosidic bonds in both endo- and exo-mode reactions. The discovery of these D-arabinan-degrading enzymes, along with the understanding of their structural basis for substrate specificity, provides valuable resources for investigating the intricate glycan architecture of mycobacterial cell wall polysaccharides and their contribution to pathogenicity.
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Affiliation(s)
- Michiko Shimokawa
- Faculty of Agriculture, Kagoshima University, Kagoshima, 890-0065, Japan
| | - Akihiro Ishiwata
- Cluster for Pioneering Research, RIKEN, Saitama, 351-0198, Japan
| | - Toma Kashima
- Department of Biotechnology, The University of Tokyo, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Chiho Nakashima
- Department of Biotechnology, The University of Tokyo, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Jiaman Li
- Department of Biotechnology, The University of Tokyo, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Riku Fukushima
- Department of Biotechnology, The University of Tokyo, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Naomi Sawai
- Faculty of Agriculture, Kagoshima University, Kagoshima, 890-0065, Japan
| | - Miku Nakamori
- Faculty of Agriculture, Kagoshima University, Kagoshima, 890-0065, Japan
| | - Yuuki Tanaka
- Faculty of Agriculture, Kagoshima University, Kagoshima, 890-0065, Japan
| | - Azusa Kudo
- Faculty of Agriculture, Kagoshima University, Kagoshima, 890-0065, Japan
| | - Sae Morikami
- Faculty of Agriculture, Kagoshima University, Kagoshima, 890-0065, Japan
| | - Nao Iwanaga
- Faculty of Agriculture, Kagoshima University, Kagoshima, 890-0065, Japan
| | - Genki Akai
- Department of Biotechnology, The University of Tokyo, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Nobutaka Shimizu
- Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki, 305-0801, Japan
| | - Takatoshi Arakawa
- Faculty of Pharmaceutical Sciences, Tokyo University of Science, Noda, Chiba, 278-8510, Japan
| | - Chihaya Yamada
- School of Agriculture, Meiji University, Kawasaki, Kanagawa, 214-8571, Japan
| | - Kanefumi Kitahara
- Faculty of Agriculture, Kagoshima University, Kagoshima, 890-0065, Japan
| | - Katsunori Tanaka
- Cluster for Pioneering Research, RIKEN, Saitama, 351-0198, Japan
- Department of Chemical Science and Engineering, Tokyo Institute of Technology, Meguro-ku, Tokyo, 152-8552, Japan
| | - Yukishige Ito
- Cluster for Pioneering Research, RIKEN, Saitama, 351-0198, Japan
- Graduate School of Science, Osaka University, Osaka, 560-0043, Japan
| | - Shinya Fushinobu
- Department of Biotechnology, The University of Tokyo, Bunkyo-ku, Tokyo, 113-8657, Japan.
- CRIIM, The University of Tokyo, Bunkyo-ku, Tokyo, 113-8657, Japan.
| | - Kiyotaka Fujita
- Faculty of Agriculture, Kagoshima University, Kagoshima, 890-0065, Japan.
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2
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Chemical synthesis of oligosaccharides and their application in new drug research. Eur J Med Chem 2023; 249:115164. [PMID: 36758451 DOI: 10.1016/j.ejmech.2023.115164] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 01/16/2023] [Accepted: 01/25/2023] [Indexed: 02/04/2023]
Abstract
Oligosaccharides are the ubiquitous molecules of life. In order to translate human bioglycosylation into clinical applications, homogeneous samples of oligosaccharides and glycoconjugates can be obtained by chemical, enzymatic or other biological methods for systematic studies. However, the structural complexity and diversity of glycans and their conjugates present a major challenge for the synthesis of such molecules. This review summarizes the chemical synthesis methods of oligosaccharides, the application of oligosaccharides in the field of medicinal chemistry according to their related biological activities, and shows the great prospect of oligosaccharides in the field of pharmaceutical chemistry.
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Rohokale R, Guo Z. Development in the Concept of Bacterial Polysaccharide Repeating Unit-Based Antibacterial Conjugate Vaccines. ACS Infect Dis 2023; 9:178-212. [PMID: 36706246 PMCID: PMC9930202 DOI: 10.1021/acsinfecdis.2c00559] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The surface of cells is coated with a dense layer of glycans, known as the cell glycocalyx. The complex glycans in the glycocalyx are involved in various biological events, such as bacterial pathogenesis, protection of bacteria from environmental stresses, etc. Polysaccharides on the bacterial cell surface are highly conserved and accessible molecules, and thus they are excellent immunological targets. Consequently, bacterial polysaccharides and their repeating units have been extensively studied as antigens for the development of antibacterial vaccines. This Review surveys the recent developments in the synthetic and immunological investigations of bacterial polysaccharide repeating unit-based conjugate vaccines against several human pathogenic bacteria. The major challenges associated with the development of functional carbohydrate-based antibacterial conjugate vaccines are also considered.
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4
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Unique C-terminal extension and interactome of Mycobacterium tuberculosis GlmU impacts it's in vivo function and the survival of pathogen. Biochem J 2021; 478:2081-2099. [PMID: 33955473 DOI: 10.1042/bcj20210170] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 05/01/2021] [Accepted: 05/06/2021] [Indexed: 11/17/2022]
Abstract
N-acetyl glucosamine-1-phosphate uridyltransferase (GlmU) is a bifunctional enzyme involved in the biosynthesis of Uridine diphosphate N-acetylglucosamine (UDP-GlcNAc). UDP-GlcNAc is a critical precursor for the synthesis of peptidoglycan and other cell wall components. The absence of a homolog in eukaryotes makes GlmU an attractive target for therapeutic intervention. Mycobacterium tuberculosis GlmU (GlmUMt) has features, such as a C-terminal extension, that are not present in GlmUorthologs from other bacteria. Here, we set out to determine the uniqueness of GlmUMt by performing in vivo complementation experiments using RvΔglmU mutant. We find that any deletion of the carboxy-terminal extension region of GlmUMt abolishes its ability to complement the function of GlmUMt. Results show orthologs of GlmU, including its closest ortholog, from Mycobacterium smegmatis, cannot complement the function of GlmUMt. Furthermore, the co-expression of GlmUMt domain deletion mutants with either acetyl or uridyltransferase activities failed to rescue the function. However, co-expression of GlmUMt point mutants with either acetyl or uridyltransferase activities successfully restored the biological function of GlmUMt, likely due to the formation of heterotrimers. Based on the interactome experiments, we speculate that GlmUMt participates in unique interactions essential for its in vivo function.
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Kumar G, Narayan R, Kapoor S. Chemical Tools for Illumination of Tuberculosis Biology, Virulence Mechanisms, and Diagnosis. J Med Chem 2020; 63:15308-15332. [PMID: 33307693 DOI: 10.1021/acs.jmedchem.0c01337] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Tuberculosis (TB) remains one of the deadliest infectious diseases and begs the scientific community to up the ante for research and exploration of completely novel therapeutic avenues. Chemical biology-inspired design of tunable chemical tools has aided in clinical diagnosis, facilitated discovery of therapeutics, and begun to enable investigation of virulence mechanisms at the host-pathogen interface of Mycobacterium tuberculosis. This Perspective highlights chemical tools specific to mycobacterial proteins and the cell lipid envelope that have furnished rapid and selective diagnostic strategies and provided unprecedented insights into the function of the mycobacterial proteome and lipidome. We discuss chemical tools that have enabled elucidating otherwise intractable biological processes by leveraging the unique lipid and metabolite repertoire of mycobacterial species. Some of these probes represent exciting starting points with the potential to illuminate poorly understood aspects of mycobacterial pathogenesis, particularly the host membrane-pathogen interactions.
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Affiliation(s)
- Gautam Kumar
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400 076, Maharashtra, India
| | - Rishikesh Narayan
- School of Chemical and Materials Sciences, Indian Institute of Technology Goa, Ponda 403 401, Goa, India
| | - Shobhna Kapoor
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400 076, Maharashtra, India.,Wadhwani Research Center for Bioengineering, Indian Institute of Technology Bombay, Mumbai 400 076, Maharashtra, India
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6
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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: 17] [Impact Index Per Article: 4.3] [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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7
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Han X, Chen C, Yan Q, Jia L, Taj A, Ma Y. Action of Dicumarol on Glucosamine-1-Phosphate Acetyltransferase of GlmU and Mycobacterium tuberculosis. Front Microbiol 2019; 10:1799. [PMID: 31481936 PMCID: PMC6710349 DOI: 10.3389/fmicb.2019.01799] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Accepted: 07/22/2019] [Indexed: 11/13/2022] Open
Abstract
Mycobacterium tuberculosis is one of most pathogenic microorganisms in the world. Previously, the bifunctional enzyme GlmU with glucosamine-1-phosphate acetyltransferase activity and N-acetylglucosamine-1-phosphate uridyltransferase activity has been suggested as a potential drug target; therefore, discovering compounds targeting GlmU acetyltransferase is necessary. The natural products were tested for inhibition of GlmU acetyltransferase activity. We found that dicumarol exhibited inhibitory effects on GlmU acetyltransferase, with a concentration achieving a 50% inhibition (IC50) value of 4.608 μg/ml (13.7 μM). The inhibition kinetics indicated that dicumarol uncompetitively inhibited acetyl CoA and showed mixed-type inhibition for glucosamine-1-phosphate (GlcN-1-P). The activity of dicumarol against M. tuberculosis H37Ra was evaluated with a minimum inhibitory concentration (MIC) value of 6.25 μg/ml (18.55 μM) in the Alamar blue assay. Dicumarol also exhibited inhibitory effects on several clinically sensitive M. tuberculosis strains and drug-resistant strains, with a range of MIC value of 6.25 to >100 μg/ml. Dicumarol increased the sensitivity of anti-tuberculosis drugs (isoniazid and rifampicin) when dicumarol was present at a low concentration. The transcriptome and proteome data of M. tuberculosis H37Ra treated by dicumarol showed that the affected genes were associated with cell wall synthesis, DNA damage and repair, metabolic processes, and signal transduction. These results provided the mechanism of dicumarol inhibition against GlmU acetyltransferase and M. tuberculosis and also suggested that dicumarol is a potential candidate for TB treatment.
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Affiliation(s)
- Xiuyan Han
- Department of Biochemistry and Molecular Biology, College of Basic Medical Sciences, Dalian Medical University, Dalian, China
| | - Changming Chen
- Department of Biochemistry and Molecular Biology, College of Basic Medical Sciences, Dalian Medical University, Dalian, China
| | - Qiulong Yan
- Department of Microbiology, College of Basic Medical Sciences, Dalian Medical University, Dalian, China
| | - Liqiu Jia
- Department of Biochemistry and Molecular Biology, College of Basic Medical Sciences, Dalian Medical University, Dalian, China
| | - Ayaz Taj
- Department of Biochemistry and Molecular Biology, College of Basic Medical Sciences, Dalian Medical University, Dalian, China
| | - Yufang Ma
- Department of Biochemistry and Molecular Biology, College of Basic Medical Sciences, Dalian Medical University, Dalian, China.,Department of Microbiology, College of Basic Medical Sciences, Dalian Medical University, Dalian, China
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8
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Wang L, Guo Z. An extensive review of studies on mycobacterium cell wall polysaccharide-related oligosaccharides – part I: Synthetic studies on arabinofuranosyl oligosaccharides. J Carbohydr Chem 2019. [DOI: 10.1080/07328303.2019.1630839] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Affiliation(s)
- Lizhen Wang
- Biology Institute, Qilu University of Technology (Shandong Academy of Sciences), Ji'nan, China
| | - Zhongwu Guo
- Department of Chemistry, University of Florida, Gainesville, FL, USA
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9
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Abstract
Actinobacteria is a group of diverse bacteria. Most species in this class of bacteria are filamentous aerobes found in soil, including the genus Streptomyces perhaps best known for their fascinating capabilities of producing antibiotics. These bacteria typically have a Gram-positive cell envelope, comprised of a plasma membrane and a thick peptidoglycan layer. However, there is a notable exception of the Corynebacteriales order, which has evolved a unique type of outer membrane likely as a consequence of convergent evolution. In this chapter, we will focus on the unique cell envelope of this order. This cell envelope features the peptidoglycan layer that is covalently modified by an additional layer of arabinogalactan . Furthermore, the arabinogalactan layer provides the platform for the covalent attachment of mycolic acids , some of the longest natural fatty acids that can contain ~100 carbon atoms per molecule. Mycolic acids are thought to be the main component of the outer membrane, which is composed of many additional lipids including trehalose dimycolate, also known as the cord factor. Importantly, a subset of bacteria in the Corynebacteriales order are pathogens of human and domestic animals, including Mycobacterium tuberculosis. The surface coat of these pathogens are the first point of contact with the host immune system, and we now know a number of host receptors specific to molecular patterns exposed on the pathogen's surface, highlighting the importance of understanding how the cell envelope of Actinobacteria is structured and constructed. This chapter describes the main structural and biosynthetic features of major components found in the actinobacterial cell envelopes and highlights the key differences between them.
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Affiliation(s)
- Kathryn C Rahlwes
- Department of Microbiology, University of Massachusetts, 639 North Pleasant Street, Amherst, MA, 01003, USA
| | - Ian L Sparks
- Department of Microbiology, University of Massachusetts, 639 North Pleasant Street, Amherst, MA, 01003, USA
| | - Yasu S Morita
- Department of Microbiology, University of Massachusetts, 639 North Pleasant Street, Amherst, MA, 01003, USA.
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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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Li W, Yu B. Gold-catalyzed glycosylation in the synthesis of complex carbohydrate-containing natural products. Chem Soc Rev 2018; 47:7954-7984. [DOI: 10.1039/c8cs00209f] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Gold(i)- and gold(iii)-catalyzed glycosylation reactions and their application in the synthesis of natural glycoconjugates are reviewed.
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Affiliation(s)
- Wei Li
- State Key Laboratory of Bioorganic and Natural Products Chemistry
- Center for Excellence in Molecular Synthesis
- Shanghai Institute of Organic Chemistry
- University of Chinese Academy of Sciences
- Chinese Academy of Sciences
| | - Biao Yu
- State Key Laboratory of Bioorganic and Natural Products Chemistry
- Center for Excellence in Molecular Synthesis
- Shanghai Institute of Organic Chemistry
- University of Chinese Academy of Sciences
- Chinese Academy of Sciences
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12
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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: 58] [Impact Index Per Article: 8.3] [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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13
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Mishra B, Manmode S, Panda RRA, Hotha S. Expedient Synthesis of a Linear Nonadecaarabinofuranoside of the Mycobacterium tuberculosis
Cellular Envelope. European J Org Chem 2017. [DOI: 10.1002/ejoc.201700712] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Bijoyananda Mishra
- Department of Chemistry; Indian Institute of Science Education and Research; Dr. Homi Bhabha Road 411008 Pune India
| | - Sujit Manmode
- Department of Chemistry; Indian Institute of Science Education and Research; Dr. Homi Bhabha Road 411008 Pune India
| | - Ravi Raja Adhikari Panda
- Department of Chemistry; Indian Institute of Science Education and Research; Dr. Homi Bhabha Road 411008 Pune India
| | - Srinivas Hotha
- Department of Chemistry; Indian Institute of Science Education and Research; Dr. Homi Bhabha Road 411008 Pune India
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14
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Islam M, Shinde GP, Hotha S. Expedient synthesis of the heneicosasaccharyl mannose capped arabinomannan of the Mycobacterium tuberculosis cellular envelope by glycosyl carbonate donors. Chem Sci 2017; 8:2033-2038. [PMID: 28451321 PMCID: PMC5398307 DOI: 10.1039/c6sc04866h] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Accepted: 11/15/2016] [Indexed: 12/19/2022] Open
Abstract
The global incidence of tuberculosis is increasing at an alarming rate, and Mycobacterium tuberculosis (Mtb) is the causative agent for tuberculosis, a disease with high mortality. Lipoarabinomannan (LAM) is one of the major components of the Mtb cellular envelope and is an attractive scaffold for developing anti-tubercular drugs, vaccines and diagnostics. Herein, a highly convergent strategy is developed to synthesize heneicosasaccharyl arabinomannan for the first time. The arabinomannan synthesized in this endeavour has several 1,2-trans or α-Araf linkages and three 1,2-cis or β-Araf linkages end capped with 1,2-trans or α-Manp linkages. All the key glycosidations were performed with alkynyl carbonate glycosyl donors under [Au]/[Ag] catalysis conditions, which gave excellent yields and stereoselectivity even for the reactions between complex and branched oligosaccharides. The resultant allyl oligosaccharide was globally deprotected to obtain the heneicosasaccharyl arabinomannan as a propyl glycoside. In summary, heneicosasaccharyl mannose capped arabinomannan synthesis was achieved in 56 steps with 0.016% overall yield.
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Affiliation(s)
- Maidul Islam
- Department of Chemistry , Indian Institute of Science Education and Research , Pune - 411 008 , India .
| | - Ganesh P Shinde
- Department of Chemistry , Indian Institute of Science Education and Research , Pune - 411 008 , India .
| | - Srinivas Hotha
- Department of Chemistry , Indian Institute of Science Education and Research , Pune - 411 008 , India .
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15
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[Au]/[Ag]-catalysed expedient synthesis of branched heneicosafuranosyl arabinogalactan motif of Mycobacterium tuberculosis cell wall. Nat Commun 2017; 8:14019. [PMID: 28120821 PMCID: PMC5288502 DOI: 10.1038/ncomms14019] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Accepted: 11/22/2016] [Indexed: 01/18/2023] Open
Abstract
Emergence of multidrug-resistant and extreme-drug-resistant strains of Mycobacterium tuberculosis (MTb) can cause serious socioeconomic burdens. Arabinogalactan present on the cellular envelope of MTb is unique and is required for its survival; access to arabinogalactan is essential for understanding the biosynthetic machinery that assembles it. Isolation from Nature is a herculean task and, as a result, chemical synthesis is the most sought after technique. Here we report a convergent synthesis of branched heneicosafuranosyl arabinogalactan (HAG) of MTb. Key furanosylations are performed using [Au]/[Ag] catalysts. The synthesis of HAG is achieved by the repetitive use of three reactions namely 1,2-trans furanoside synthesis by propargyl 1,2-orthoester donors, unmasking of silyl ether, and conversion of n-pentenyl furanosides into 1,2-orthoesters. Synthesis of HAG is achieved in 47 steps (with an overall yield of 0.09%) of which 21 are installation of furanosidic linkages in a stereoselective manner. Arabinogalactan forms parts of the cellular envelope of Mycobacterium tuberculosis, however due to its size chemical synthesis is a massive task. Here the authors report the synthesis of branched heneicosafuranosyl arabinogalactan fragment by repeated use of a Au/Ag-catalysed glycosylation methodology.
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Lee BY, Oh JW, Baek JY, Jeon HB, Kim KS. Phthalic Anhydride-Mediated Direct Glycosylation of Anomeric Hydroxy Arabinofuranose: Synthesis of Repeating Oligoarabinofuranoside and Tetradecasaccharide Arabinan Motif of Mycobacterial Cell Wall. J Org Chem 2016; 81:11372-11383. [DOI: 10.1021/acs.joc.6b01723] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Bo-Young Lee
- Center
for Bioactive Molecular Hybrids and Department of Chemistry, Yonsei University, Seoul 120-749, Korea
| | - Jung Woo Oh
- Center
for Bioactive Molecular Hybrids and Department of Chemistry, Yonsei University, Seoul 120-749, Korea
| | - Ju Yuel Baek
- Center
for Bioactive Molecular Hybrids and Department of Chemistry, Yonsei University, Seoul 120-749, Korea
| | - Heung Bae Jeon
- Department
of Chemistry, Kwangwoon University, Seoul 139-701, Korea
| | - Kwan Soo Kim
- Center
for Bioactive Molecular Hybrids and Department of Chemistry, Yonsei University, Seoul 120-749, Korea
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17
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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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Soni V, Upadhayay S, Suryadevara P, Samla G, Singh A, Yogeeswari P, Sriram D, Nandicoori VK. Depletion of M. tuberculosis GlmU from Infected Murine Lungs Effects the Clearance of the Pathogen. PLoS Pathog 2015; 11:e1005235. [PMID: 26489015 PMCID: PMC4619583 DOI: 10.1371/journal.ppat.1005235] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2015] [Accepted: 09/27/2015] [Indexed: 01/06/2023] Open
Abstract
M. tuberculosis N-acetyl-glucosamine-1-phosphate uridyltransferase (GlmUMtb) is a bi-functional enzyme engaged in the synthesis of two metabolic intermediates N-acetylglucosamine-1-phosphate (GlcNAc-1-P) and UDP-GlcNAc, catalyzed by the C- and N-terminal domains respectively. UDP-GlcNAc is a key metabolite essential for the synthesis of peptidoglycan, disaccharide linker, arabinogalactan and mycothiols. While glmUMtb was predicted to be an essential gene, till date the role of GlmUMtb in modulating the in vitro growth of Mtb or its role in survival of pathogen ex vivo / in vivo have not been deciphered. Here we present the results of a comprehensive study dissecting the role of GlmUMtb in arbitrating the survival of the pathogen both in vitro and in vivo. We find that absence of GlmUMtb leads to extensive perturbation of bacterial morphology and substantial reduction in cell wall thickness under normoxic as well as hypoxic conditions. Complementation studies show that the acetyl- and uridyl- transferase activities of GlmUMtb are independently essential for bacterial survival in vitro, and GlmUMtb is also found to be essential for mycobacterial survival in THP-1 cells as well as in guinea pigs. Depletion of GlmUMtb from infected murine lungs, four weeks post infection, led to significant reduction in the bacillary load. The administration of Oxa33, a novel oxazolidine derivative that specifically inhibits GlmUMtb, to infected mice resulted in significant decrease in the bacillary load. Thus our study establishes GlmUMtb as a strong candidate for intervention measures against established tuberculosis infections. The synthesis of the Mtb cell wall involves a cascade of reactions catalyzed by cytosolic and cell membrane-bound enzymes. The reaction catalyzed by GlmUMtb (an enzyme with acetyltransferase and uridyltransferase activities) generates UDP-GlcNAc, a central nucleotide-sugar building block of the cell wall. Apart from cell wall synthesis UDP-GlcNAc is an essential metabolite participating in other cellular processes including disaccharide linker and mycothiol biosynthesis. GlmUMtb shares very little sequence similarity with eukaryotic acetyltransferase and uridyltransferase enzymes. Many pathogens have alternative pathway(s) for foraging GlcNAc from the host. The present study was undertaken to see the effects of depleting GlmUMtb on pathogen survival in the host animal. We have generated a conditional gene replacement mutant of glmUMtb and find that depletion of GlmUMtb at any stage of bacterial growth or in mice infected with Mtb including a well-established infection, results in irreversible bacterial death due to perturbation of cell wall synthesis. We have developed a novel anti-GlmUMtb inhibitor (Oxa33), identified its binding site on GlmUMtb, and shown its specificity for GlmUMtb. The study demonstrates that GlmUMtb is a promising target for therapeutic intervention and Oxa33 can be pursued as a lead molecule.
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Affiliation(s)
- Vijay Soni
- National Institute of Immunology, New Delhi, India
- Department of Pharmacy, Birla Institute of Technology and Science-Pilani, Hyderabad Campus, Hyderabad, India
| | | | - Priyanka Suryadevara
- Department of Pharmacy, Birla Institute of Technology and Science-Pilani, Hyderabad Campus, Hyderabad, India
| | - Ganesh Samla
- Department of Pharmacy, Birla Institute of Technology and Science-Pilani, Hyderabad Campus, Hyderabad, India
| | - Archana Singh
- CSIR-Institute of Genomics and Integrative Biology, New Delhi, India
| | - Perumal Yogeeswari
- Department of Pharmacy, Birla Institute of Technology and Science-Pilani, Hyderabad Campus, Hyderabad, India
| | - Dharmarajan Sriram
- Department of Pharmacy, Birla Institute of Technology and Science-Pilani, Hyderabad Campus, Hyderabad, India
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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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20
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Larrouy-Maumus G, Gilleron M, Skovierová H, Zuberogoitia S, Brennan PJ, Puzo G, Jackson M, Nigou J. A glycomic approach reveals a new mycobacterial polysaccharide. Glycobiology 2015; 25:1163-71. [PMID: 26261090 DOI: 10.1093/glycob/cwv061] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2015] [Accepted: 08/05/2015] [Indexed: 12/26/2022] Open
Abstract
Mycobacterium tuberculosis lipoarabinomannan (LAM) and biosynthetically related lipoglycans and glycans play an important role in host-pathogen interactions. Therefore, the elucidation of the complete biosynthetic pathways of these important molecules is expected to afford novel therapeutic targets. The characterization of biosynthetic enzymes and transporters involved in the formation and localization of these complex macromolecules in the bacterial cell envelope largely relies on genetic manipulation of mycobacteria and subsequent analyses of lipoglycan structural alterations. However, lipoglycans are present in relatively low amounts. Their purification to homogeneity remains tedious and time-consuming. To overcome these issues and to reduce the biomass and time required for lipoglycan purification, we report here the development of a methodology to efficiently purify lipoglycans by sodium deoxycholate-polyacrylamide gel electrophoresis. This faster purification method can be applied on a small amount of mycobacterial cells biomass (10-50 mg), resulting in tens of micrograms of purified lipoglycans. This amount of purified products was found to be sufficient to undertake structural analyses of lipoglycans and glycans carbohydrate domains by a combination of highly sensitive analytical procedures, involving cryoprobe NMR analysis of intact macromolecules and chemical degradations monitored by gas chromatography and capillary electrophoresis. This glycomic approach was successfully applied to the purification and structural characterization of a newly identified polysaccharide, structurally related to LAM, in the model fast-growing species Mycobacterium smegmatis.
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Affiliation(s)
- Gérald Larrouy-Maumus
- CNRS, Institut de Pharmacologie et de Biologie Structurale (IPBS), UMR 5089 CNRS/Université Paul Sabatier, 205 route de Narbonne, BP 64182, F-31077 Toulouse Cedex 4, France Université de Toulouse, Université Paul Sabatier, IPBS, F-31077 Toulouse, France
| | - Martine Gilleron
- CNRS, Institut de Pharmacologie et de Biologie Structurale (IPBS), UMR 5089 CNRS/Université Paul Sabatier, 205 route de Narbonne, BP 64182, F-31077 Toulouse Cedex 4, France Université de Toulouse, Université Paul Sabatier, IPBS, F-31077 Toulouse, France
| | - Henrieta Skovierová
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523-1682, USA
| | - Sophie Zuberogoitia
- CNRS, Institut de Pharmacologie et de Biologie Structurale (IPBS), UMR 5089 CNRS/Université Paul Sabatier, 205 route de Narbonne, BP 64182, F-31077 Toulouse Cedex 4, France Université de Toulouse, Université Paul Sabatier, IPBS, F-31077 Toulouse, France
| | - Patrick J Brennan
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523-1682, USA
| | - Germain Puzo
- CNRS, Institut de Pharmacologie et de Biologie Structurale (IPBS), UMR 5089 CNRS/Université Paul Sabatier, 205 route de Narbonne, BP 64182, F-31077 Toulouse Cedex 4, France Université de Toulouse, Université Paul Sabatier, IPBS, F-31077 Toulouse, France
| | - Mary Jackson
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523-1682, USA
| | - Jérôme Nigou
- CNRS, Institut de Pharmacologie et de Biologie Structurale (IPBS), UMR 5089 CNRS/Université Paul Sabatier, 205 route de Narbonne, BP 64182, F-31077 Toulouse Cedex 4, France Université de Toulouse, Université Paul Sabatier, IPBS, F-31077 Toulouse, France
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21
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Wheat WH, Dhouib R, Angala SK, Larrouy-Maumus G, Dobos K, Nigou J, Spencer JS, Jackson M. The presence of a galactosamine substituent on the arabinogalactan of Mycobacterium tuberculosis abrogates full maturation of human peripheral blood monocyte-derived dendritic cells and increases secretion of IL-10. Tuberculosis (Edinb) 2015; 95:476-89. [PMID: 26048627 DOI: 10.1016/j.tube.2015.04.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Accepted: 04/08/2015] [Indexed: 12/28/2022]
Abstract
Slow-growing and pathogenic Mycobacterium spp. are characterized by the presence of galactosamine (GalN) that modifies the interior branched arabinosyl residues of the arabinogalactan (AG) that is a major heteropolysaccharide cell wall component. The availability of null mutants of the polyprenyl-phospho-N-acetylgalactosaminyl synthase (Rv3631, PpgS) and the (N-acetyl-) galactosaminyl transferase (Rv3779) of Mycobacterium tuberculosis (Mtb) has provided a means to elucidate the role of the GalN substituent of AG in terms of host-pathogen interactions. Comparisons of treating human peripheral blood monocyte-derived dendritic cells (hPMC-DCs) with wild-type, Rv3631 and Rv3779 mutant strains of Mtb revealed increased expression of DC maturation markers, decreased affinity for a soluble DC-SIGN probe, reduced IL-10 secretion and increased TLR-2-mediated NF-κB activation among GalN-deficient Mtb strains compared to GalN-producing strains. Analysis of surface expression of a panel of defined or putative DC-SIGN ligands on both WT strains or either Rv3631 or Rv3779 mutant did not show significant differences suggesting that the role of the GalN substituent of AG may be to modulate access of the bacilli to immunologically-relevant receptor domains on DCs or contribute to higher ordered pathogen associated molecular pattern (PAMP)/pattern recognition receptor (PRR) interactions rather than the GalN-AG components having a direct immunological effect per se.
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Affiliation(s)
- William H Wheat
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523-1682, USA.
| | - Rabeb Dhouib
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523-1682, USA
| | - Shiva K Angala
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523-1682, USA
| | - Gérald Larrouy-Maumus
- CNRS, IPBS (Institut de Pharmacologie et de Biologie Structurale), Département Mécanismes Moléculaires des Infections Mycobactériennes, 205 route de Narbonne, F-31077 Toulouse, France; Université de Toulouse, UPS, IPBS, F-31077 Toulouse, France
| | - Karen Dobos
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523-1682, USA
| | - Jérôme Nigou
- CNRS, IPBS (Institut de Pharmacologie et de Biologie Structurale), Département Mécanismes Moléculaires des Infections Mycobactériennes, 205 route de Narbonne, F-31077 Toulouse, France; Université de Toulouse, UPS, IPBS, F-31077 Toulouse, France
| | - John S Spencer
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523-1682, USA
| | - Mary Jackson
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523-1682, USA
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Alderwick LJ, Harrison J, Lloyd GS, Birch HL. The Mycobacterial Cell Wall--Peptidoglycan and Arabinogalactan. Cold Spring Harb Perspect Med 2015; 5:a021113. [PMID: 25818664 DOI: 10.1101/cshperspect.a021113] [Citation(s) in RCA: 122] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
The mycobacterial bacillus is encompassed by a remarkably elaborate cell wall structure. The mycolyl-arabinogalactan-peptidoglycan (mAGP) complex is essential for the viability of Mycobacterium tuberculosis and maintains a robust basal structure supporting the upper "myco-membrane." M. tuberculosis peptidoglycan, although appearing to be unexceptional at first glance, contains a number of unique molecular subtleties that become particularly important as the TB-bacilli enters into nonreplicative growth during dormancy. Arabinogalactan, a highly branched polysaccharide, serves to connect peptidoglycan with the outer mycolic acid layer, and a variety of unique glycolsyltransferases are used for its assembly. In this review, we shall explore the microbial chemistry of this unique heteropolysacchride, examine the molecular genetics that underpins its fabrication, and discuss how the essential biosynthetic process might be exploited for the development of future anti-TB chemotherapies.
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Affiliation(s)
- Luke J Alderwick
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Birmingham B15 2TT, United Kingdom
| | - James Harrison
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Birmingham B15 2TT, United Kingdom
| | - Georgina S Lloyd
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Birmingham B15 2TT, United Kingdom
| | - Helen L Birch
- Institute of Microbiology and Infection, School of Biosciences, University of Birmingham, Birmingham B15 2TT, United Kingdom
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23
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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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24
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Thadke SA, Mishra B, Hotha S. Facile synthesis of β- and α-arabinofuranosides and application to cell wall motifs of M. tuberculosis. Org Lett 2013; 15:2466-9. [PMID: 23659307 DOI: 10.1021/ol400931p] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Propargyl 1,2-orthoesters of arabinose are exploited for the synthesis of 1,2-trans furanosides; easily accessible 1,2-trans ribofuranosides are converted to challenging 1,2-cis-arabinofuranosides by oxidoreduction. Utility of these protocols was demonstrated by the successful synthesis of major structural motifs present in the cell surface of Mycobacterium tuberculosis. Key furanosylations were carried out under gold-catalyzed glycosidation conditions.
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Affiliation(s)
- Shivaji A Thadke
- Department of Chemistry, Indian Institute of Science Education and Research , Pune 411 008, India
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25
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Pieper S, Unterieser I, Mann F, Mischnick P. A new arabinomannan from the cell wall of the chlorococcal algae Chlorella vulgaris. Carbohydr Res 2012; 352:166-76. [DOI: 10.1016/j.carres.2012.02.007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2011] [Revised: 02/09/2012] [Accepted: 02/10/2012] [Indexed: 11/24/2022]
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26
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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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27
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Rombouts Y, Brust B, Ojha AK, Maes E, Coddeville B, Elass-Rochard E, Kremer L, Guerardel Y. Exposure of mycobacteria to cell wall-inhibitory drugs decreases production of arabinoglycerolipid related to Mycolyl-arabinogalactan-peptidoglycan metabolism. J Biol Chem 2012; 287:11060-9. [PMID: 22315220 DOI: 10.1074/jbc.m111.327387] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The "cell wall core" consisting of a mycolyl-arabinogalactan-peptidoglycan (mAGP) complex represents the hallmark of the mycobacterial cell envelope. It has been the focus of intense research at both structural and biosynthetic levels during the past few decades. Because it is essential, mAGP is also regarded as a target for several antitubercular drugs. Herein, we demonstrate that exposure of Mycobacterium bovis Bacille Calmette-Guérin or Mycobacterium marinum to thiacetazone, a second line antitubercular drug, is associated with a severe decrease in the level of a major apolar glycolipid. This inhibition requires MmaA4, a methyltransferase reported to participate in the activation process of thiacetazone. Following purification, this glycolipid was subjected to detailed structural analyses, combining gas-liquid chromatography, mass spectrometry, and nuclear magnetic resonance. This allowed to identify it as a 5-O-mycolyl-β-Araf-(1→2)-5-O-mycolyl-α-Araf-(1→1)-Gro, designated dimycolyl diarabinoglycerol (DMAG). The presence of DMAG was subsequently confirmed in other slow growing pathogenic species, including Mycobacterium tuberculosis. DMAG production was stimulated in the presence of exogenous glycerol. Interestingly, DMAG appears structurally identical to the terminal portion of the mycolylated arabinosyl motif of mAGP, and the metabolic relationship between these two components was provided using antitubercular drugs such as ethambutol or isoniazid known to inhibit the biosynthesis of arabinogalactan or mycolic acid, respectively. Finally, DMAG was identified in the cell wall of M. tuberculosis. This opens the possibility of a potent biological function for DMAG that may be important to mycobacterial pathogenesis.
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Affiliation(s)
- Yoann Rombouts
- Université Lille Nord de France, Université Lille 1, Unité de Glycobiologie Structurale et Fonctionnelle (UGSF), F-59650 Villeneuve d'Ascq, France
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28
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Zhang J, Angala SK, Pramanik PK, Li K, Crick DC, Liav A, Jozwiak A, Swiezewska E, Jackson M, Chatterjee D. Reconstitution of functional mycobacterial arabinosyltransferase AftC proteoliposome and assessment of decaprenylphosphorylarabinose analogues as arabinofuranosyl donors. ACS Chem Biol 2011; 6:819-28. [PMID: 21595486 DOI: 10.1021/cb200091m] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Arabinosyltransferases are a family of membrane-bound glycosyltransferases involved in the biosynthesis of the arabinan segment of two key glycoconjugates, arabinogalactan and lipoarabinomannan, in the mycobacterial cell wall. All arabinosyltransferases identified have been found to be essential for the growth of Mycobcterium tuberculosis and are potential targets for developing new antituberculosis drugs. Technical bottlenecks in designing enzyme assays for screening for inhibitors of these enzymes are (1) the enzymes are membrane proteins and refractory to isolation; and (2) the sole arabinose donor, decaprenylphosphoryl-d-arabinofuranose is sparingly produced and difficult to isolate, and commercial substrates are not available. In this study, we have synthesized several analogues of decaprenylphosphoryl-d-arabinofuranose by varying the chain length and investigated their arabinofuranose (Araf) donating capacity. In parallel, an essential arabinosyltransferase (AftC), an enzyme that introduces α-(1→3) branch points in the internal arabinan domain in both arabinogalactan and lipoarabinomannan synthesis, has been expressed, solubilized, and purified for the first time. More importantly, it has been shown that the AftC is active only when reconstituted in a proteoliposome using mycobacterial phospholipids and has a preference for diacylated phosphatidylinositoldimannoside (Ac(2)PIM(2)), a major cell wall associated glycolipid. α-(1→3) branched arabinans were generated when AftC-liposome complex was used in assays with the (Z,Z)-farnesylphosphoryl d-arabinose and linear α-d-Araf-(1→5)(3-5) oligosaccharide acceptors and not with the acceptor that had a α-(1→3) branch point preintroduced.
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Affiliation(s)
- Jian Zhang
- ADA Technologies, Inc., 8100 Shaffer Parkway, Suite 130, Littleton, Colorado 80127, United States
| | - Shiva K. Angala
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado 80523-1682, United States
| | - Pradeep K. Pramanik
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado 80523-1682, United States
| | - Kai Li
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado 80523-1682, United States
| | - Dean C. Crick
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado 80523-1682, United States
| | - Avraham Liav
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado 80523-1682, United States
| | - Adam Jozwiak
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5A, 02-106 Warsaw, Poland
| | - Ewa Swiezewska
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5A, 02-106 Warsaw, Poland
| | - Mary Jackson
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado 80523-1682, United States
| | - Delphi Chatterjee
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado 80523-1682, United States
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Ishiwata A, Ito Y. Synthesis of docosasaccharide arabinan motif of mycobacterial cell wall. J Am Chem Soc 2011; 133:2275-91. [PMID: 21287985 DOI: 10.1021/ja109932t] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Mycobacterial arabinan is a common constituent of both arabinogalactan (AG) and lipoarabinomannan (LAM). In this study, synthesis of β-Araf containing common arabinan docosasaccharide motif (22 Araf monomer units) of mycobacterial cell wall was achieved. Our synthetic strategy toward arabinan involves (1) the stereoselective β-arabinofuranosylation using both 3,5-O-TIPDS-protected and NAP-protected arabinofuranosyl donors for straightforward intermolecular glycosylation and intramolecular aglycon delivery (IAD), respectively, and (2) the convergent fragment coupling with branched fragments at the linear sequence using thioglycoside donor obtained from the corresponding acetonide at the reducing terminal of each fragment through a three-step procedure. Because the acetonide at the reducing terminal of all fragments would be converted to thioglycoside as the glycosyl donor, and mainly Bn ether protections were used, our strategy will be readily applicable to the synthesis of more complex arabinan, arabinogalactan, and arabinomycolate derived from mycobacterial CWS.
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Affiliation(s)
- Akihiro Ishiwata
- RIKEN Advanced Science Institute, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
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30
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Harvey DJ. Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: an update for the period 2005-2006. MASS SPECTROMETRY REVIEWS 2011; 30:1-100. [PMID: 20222147 DOI: 10.1002/mas.20265] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
This review is the fourth update of the original review, published in 1999, on the application of MALDI mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2006. The review covers fundamental studies, fragmentation of carbohydrate ions, method developments, and applications of the technique to the analysis of different types of carbohydrate. Specific compound classes that are covered include carbohydrate polymers from plants, N- and O-linked glycans from glycoproteins, glycated proteins, glycolipids from bacteria, glycosides, and various other natural products. There is a short section on the use of MALDI-TOF mass spectrometry for the study of enzymes involved in glycan processing, a section on industrial processes, particularly the development of biopharmaceuticals and a section on the use of MALDI-MS to monitor products of chemical synthesis of carbohydrates. Large carbohydrate-protein complexes and glycodendrimers are highlighted in this final section.
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Affiliation(s)
- David J Harvey
- Department of Biochemistry, Oxford Glycobiology Institute, University of Oxford, Oxford OX1 3QU, UK.
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31
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Skovierová H, Larrouy-Maumus G, Pham H, Belanová M, Barilone N, Dasgupta A, Mikusová K, Gicquel B, Gilleron M, Brennan PJ, Puzo G, Nigou J, Jackson M. Biosynthetic origin of the galactosamine substituent of Arabinogalactan in Mycobacterium tuberculosis. J Biol Chem 2010; 285:41348-55. [PMID: 21030587 DOI: 10.1074/jbc.m110.188110] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The arabinogalactan (AG) of slow growing pathogenic Mycobacterium spp. is characterized by the presence of galactosamine (GalN) modifying some of the interior branched arabinosyl residues. The biosynthetic origin of this substituent and its role(s) in the physiology and/or pathogenicity of mycobacteria are not known. We report on the discovery of a polyprenyl-phospho-N-acetylgalactosaminyl synthase (PpgS) and the glycosyltransferase Rv3779 from Mycobacterium tuberculosis required, respectively, for providing and transferring the GalN substrate for the modification of AG. Disruption of either ppgS (Rv3631) or Rv3779 totally abolished the synthesis of the GalN substituent of AG in M. tuberculosis H37Rv. Conversely, expression of ppgS in Mycobacterium smegmatis conferred upon this species otherwise devoid of ppgS ortholog and any detectable polyprenyl-phospho-N-acetylgalactosaminyl synthase activity the ability to synthesize polyprenyl-phospho-N-acetylgalactosamine (polyprenyl-P-GalNAc) from polyprenyl-P and UDP-GalNAc. Interestingly, this catalytic activity was increased 40-50-fold by co-expressing Rv3632, the encoding gene of a small membrane protein apparently co-transcribed with ppgS in M. tuberculosis H37Rv. The discovery of this novel lipid-linked sugar donor and the involvement of a the glycosyltransferase C-type glycosyltransferase in its transfer onto its final acceptor suggest that pathogenic mycobacteria modify AG on the periplasmic side of the plasma membrane. The availability of a ppgS knock-out mutant of M. tuberculosis provides unique opportunities to investigate the physiological function of the GalN substituent and the potential impact it may have on host-pathogen interactions.
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Affiliation(s)
- Henrieta Skovierová
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado 80523-1682, USA
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32
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Kaur D, Guerin ME, Skovierová H, Brennan PJ, Jackson M. Chapter 2: Biogenesis of the cell wall and other glycoconjugates of Mycobacterium tuberculosis. ADVANCES IN APPLIED MICROBIOLOGY 2009; 69:23-78. [PMID: 19729090 DOI: 10.1016/s0065-2164(09)69002-x] [Citation(s) in RCA: 148] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The re-emergence of tuberculosis in its present-day manifestations - single, multiple and extensive drug-resistant forms and as HIV-TB coinfections - has resulted in renewed research on fundamental questions such as the nature of the organism itself, Mycobacterium tuberculosis, the molecular basis of its pathogenesis, definition of the immunological response in animal models and humans, and development of new intervention strategies such as vaccines and drugs. Foremost among these developments has been the precise chemical definition of the complex and distinctive cell wall of M. tuberculosis, elucidation of the relevant pathways and underlying genetics responsible for the synthesis of the hallmark moieties of the tubercle bacillus such as the mycolic acid-arabinogalactan-peptidoglycan complex, the phthiocerol- and trehalose-containing effector lipids, the phosphatidylinositol-containing mannosides, lipomannosides and lipoarabinomannosides, major immunomodulators, and others. In this review, the laboratory personnel who have been the focal point of some to these developments review recent progress towards a comprehensive understanding of the basic physiology and functions of the cell wall of M. tuberculosis.
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Affiliation(s)
- Devinder Kaur
- Department of Microbiology, Immunology and Pathology, Mycobacteria Research Laboratories, Colorado State University, Fort Collins, CO 80523-1682, USA
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33
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Transfer of the first arabinofuranose residue to galactan is essential for Mycobacterium smegmatis viability. J Bacteriol 2008; 190:5248-55. [PMID: 18556798 DOI: 10.1128/jb.00028-08] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The mycobacterial arabinan is an elaborate component of the cell wall with multiple glycosyl linkages and no repeating units. In Mycobacterium spp., the Emb proteins (EmbA, EmbB, and EmbC) have been identified as putative mycobacterial arabinosyltransferases implicated in the biogenesis of the cell wall arabinan. Furthermore, it is now evident that the EmbA and EmbB proteins are involved in the assembly of the nonreducing terminal motif of arabinogalactan and EmbC is involved in transferring arabinose, perhaps in the early stage of arabinan synthesis in lipoarabinomannan. It has also been shown that the Emb proteins are a target of the antimycobacterial drug ethambutol (EMB). In the search for additional mycobacterial arabinosyltransferases in addition to the Emb proteins, we disrupted MSMEG_6386 (an orthologue of Rv3792 and a gene upstream of embC) in Mycobacterium smegmatis. Allelic exchange at the chromosomal MSMEG_6386 locus of M. smegmatis could only be achieved in the presence of a rescue plasmid carrying a functional copy of MSMEG_6386 or Rv3792, strongly suggesting that MSMEG_6386 is essential. An in vitro arabinosyltransferase assay using a membrane preparation from M. smegmatis expressing Rv3792 and synthetic beta-d-Galf-(1-->5)-beta-D-Galf-(1-->6)-beta-D-Galf-octyl and beta-D-Galf-(1-->6)-beta-D-Galf-(1-->5)-beta-D-Galf-octyl showed that Rv3792 gene product can transfer an arabinose residue to the C-5 position of the internal 6-linked galactose. The reactions were insensitive to EMB, and when alpha-d-Manp-(1-->6)-alpha-D-Manp-(1-->6)-alpha-D-Manp-octylthiomethyl was used as an acceptor, no product was formed. These observations indicate that transfer of the first arabinofuranose residue to galactan is essential for M. smegmatis viability.
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Zhang W, Jones VC, Scherman MS, Mahapatra S, Crick D, Bhamidi S, Xin Y, McNeil MR, Ma Y. Expression, essentiality, and a microtiter plate assay for mycobacterial GlmU, the bifunctional glucosamine-1-phosphate acetyltransferase and N-acetylglucosamine-1-phosphate uridyltransferase. Int J Biochem Cell Biol 2008; 40:2560-71. [PMID: 18573680 DOI: 10.1016/j.biocel.2008.05.003] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2007] [Revised: 04/29/2008] [Accepted: 05/05/2008] [Indexed: 11/26/2022]
Abstract
UDP-N-acetyl-D-glucosamine (UDP-GlcNAc) is an essential precursor of peptidoglycan and the rhamnose-GlcNAc linker region of mycobacterial cell wall. In Mycobacterium tuberculosis H37Rv genome, Rv1018c shows strong homology to the GlmU protein involved in the formation of UDP-GlcNAc from other bacteria. GlmU is a bifunctional enzyme that catalyzes two sequential steps in UDP-GlcNAc biosynthesis. Glucosamine-1-phosphate acetyl transferase catalyzes the formation of N-acetylglucosamine-1-phosphate, and N-acetylglucosamine-1-phosphate uridylyltransferase catalyzes the formation of UDP-GlcNAc. Since inhibition of peptidoglycan synthesis often results in cell lysis, M. tuberculosis GlmU is a potential anti-tuberculosis (TB) drug target. In this study we cloned M. tuberculosis Rv1018c (glmU gene) and expressed soluble GlmU protein in E. coli BL21(DE3). Enzymatic assays showed that M. tuberculosis GlmU protein exhibits both glucosamine-1-phosphate acetyltransferase and N-acetylglucosamine-1-phosphate uridylyltransferase activities. We also investigated the effect on Mycobacterium smegmatis when the activity of GlmU is fully removed or reduced via a genetic approach. The results showed that activity of GlmU is required for growth of M. smegmatis as the bacteria did not grow in the absence of active GlmU enzyme. As the amount of functional GlmU enzyme was gradually reduced in a temperature shift experiment, the M. smegmatis cells became non-viable and their morphology changed from a normal rod shape to stubby-rounded morphology and in some cases they lysed. Finally a microtiter plate based assay for GlmU activity with an OD340 read out was developed. These studies therefore support the further development of M. tuberculosis GlmU enzyme as a target for new anti-tuberculosis drugs.
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Affiliation(s)
- Wenli Zhang
- Department of Biochemistry and Molecular Biology, Dalian Medical University, Dalian 116044, China
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Bhamidi S, Scherman MS, Rithner CD, Prenni JE, Chatterjee D, Khoo KH, McNeil MR. The identification and location of succinyl residues and the characterization of the interior arabinan region allow for a model of the complete primary structure of Mycobacterium tuberculosis mycolyl arabinogalactan. J Biol Chem 2008; 283:12992-3000. [PMID: 18303028 DOI: 10.1074/jbc.m800222200] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The complex cell wall of Mycobacterium tuberculosis is the hallmark of acid fast bacteria and is responsible for much of its physiological characteristics. Hence, much effort has been made to determine its primary structure. Such studies have been hampered by its extreme complexity. Also, its insolubility leads to difficulties determining the presence or absence of base labile groups. We have used an endogenous arabinase to solubilize the arabinan region of the cell wall and have shown using mass spectrometry and NMR that succinyl esters are present on O2 of the inner-branched 1,3,5-alpha-d-arabinofuranosyl residues. In addition, an inner arabinan region of 14 linear alpha-1,5 arabinofuranosyl residues has been identified. These and earlier results now allow the presentation of a model of the entire primary structure of the mycobacterial mycolyl arabinogalactan highlighted by three arabinan chains of 31 residues each.
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Affiliation(s)
- Suresh Bhamidi
- Department of Microbiology, Colorado State University, Fort Collins, Colorado 80523, USA
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Gokhale RS, Saxena P, Chopra T, Mohanty D. Versatile polyketide enzymatic machinery for the biosynthesis of complex mycobacterial lipids. Nat Prod Rep 2007; 24:267-77. [PMID: 17389997 DOI: 10.1039/b616817p] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
The cell envelope of Mycobacterium tuberculosis (Mtb) is a treasure house of a variety of biologically active molecules with fascinating architectures. The decoding of the genetic blueprint of Mtb in recent years has provided the impetus for dissecting the metabolic pathways involved in the biosynthesis of lipidic metabolites. The focus of the Highlight is to emphasize the functional role of polyketide synthase (PKS) proteins in the biosynthesis of complex mycobacterial lipids. The catalytic as well as mechanistic versatility of PKS. in generating metabolic diversity and the significance of recently discovered fatty acyl-AMP ligases in establishing "biochemical crosstalk" between fatty acid synthases (FASs) and PKSs is described. The phenotypic heterogeneity and remodeling of the mycobacterial cell wall in its aetiopathogenesis is discussed.
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Affiliation(s)
- Rajesh S Gokhale
- National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, 110 067, India.
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