1
|
Savková K, Danchenko M, Fabianová V, Bellová J, Bencúrová M, Huszár S, Korduláková J, Siváková B, Baráth P, Mikušová K. Compartmentalization of galactan biosynthesis in mycobacteria. J Biol Chem 2024; 300:105768. [PMID: 38367664 PMCID: PMC10951656 DOI: 10.1016/j.jbc.2024.105768] [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: 11/27/2023] [Revised: 01/31/2024] [Accepted: 02/12/2024] [Indexed: 02/19/2024] Open
Abstract
Galactan polymer is a prominent component of the mycobacterial cell wall core. Its biogenesis starts at the cytoplasmic side of the plasma membrane by a build-up of the linker disaccharide [rhamnosyl (Rha) - N-acetyl-glucosaminyl (GlcNAc) phosphate] on the decaprenyl-phosphate carrier. This decaprenyl-P-P-GlcNAc-Rha intermediate is extended by two bifunctional galactosyl transferases, GlfT1 and GlfT2, and then it is translocated to the periplasmic space by an ABC transporter Wzm-Wzt. The cell wall core synthesis is finalized by the action of an array of arabinosyl transferases, mycolyl transferases, and ligases that catalyze an attachment of the arabinogalactan polymer to peptidoglycan through the linker region. Based on visualization of the GlfT2 enzyme fused with fluorescent tags it was proposed that galactan polymerization takes place in a specific compartment of the mycobacterial cell envelope, the intracellular membrane domain, representing pure plasma membrane free of cell wall components (previously denoted as the "PMf" domain), which localizes to the polar region of mycobacteria. In this work, we examined the activity of the galactan-producing cellular machine in the cell-wall containing cell envelope fraction and in the cell wall-free plasma membrane fraction prepared from Mycobacterium smegmatis by the enzyme assays using radioactively labeled substrate UDP-[14C]-galactose as a tracer. We found that despite a high abundance of GlfT2 in both of these fractions as confirmed by their thorough proteomic analyses, galactan is produced only in the reaction mixtures containing the cell wall components. Our findings open the discussion about the distribution of GlfT2 and the regulation of its activity in mycobacteria.
Collapse
Affiliation(s)
- Karin Savková
- Department of Biochemistry, Faculty of Natural Sciences, Comenius University in Bratislava, Bratislava, Slovakia
| | - Maksym Danchenko
- Institute of Chemistry, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Viktória Fabianová
- Department of Biochemistry, Faculty of Natural Sciences, Comenius University in Bratislava, Bratislava, Slovakia
| | - Jana Bellová
- Institute of Chemistry, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Mária Bencúrová
- Department of Biochemistry, Faculty of Natural Sciences, Comenius University in Bratislava, Bratislava, Slovakia
| | - Stanislav Huszár
- Department of Biochemistry, Faculty of Natural Sciences, Comenius University in Bratislava, Bratislava, Slovakia
| | - Jana Korduláková
- Department of Biochemistry, Faculty of Natural Sciences, Comenius University in Bratislava, Bratislava, Slovakia
| | - Barbara Siváková
- Institute of Chemistry, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Peter Baráth
- Institute of Chemistry, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Katarína Mikušová
- Department of Biochemistry, Faculty of Natural Sciences, Comenius University in Bratislava, Bratislava, Slovakia.
| |
Collapse
|
2
|
Harnagel AP, Sheshova M, Zheng M, Zheng M, Skorupinska-Tudek K, Swiezewska E, Lupoli TJ. Preference of Bacterial Rhamnosyltransferases for 6-Deoxysugars Reveals a Strategy To Deplete O-Antigens. J Am Chem Soc 2023. [PMID: 37437030 PMCID: PMC10375533 DOI: 10.1021/jacs.3c03005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/14/2023]
Abstract
Bacteria synthesize hundreds of bacteria-specific or "rare" sugars that are absent in mammalian cells and enriched in 6-deoxy monosaccharides such as l-rhamnose (l-Rha). Across bacteria, l-Rha is incorporated into glycans by rhamnosyltransferases (RTs) that couple nucleotide sugar substrates (donors) to target biomolecules (acceptors). Since l-Rha is required for the biosynthesis of bacterial glycans involved in survival or host infection, RTs represent potential antibiotic or antivirulence targets. However, purified RTs and their unique bacterial sugar substrates have been difficult to obtain. Here, we use synthetic nucleotide rare sugar and glycolipid analogs to examine substrate recognition by three RTs that produce cell envelope components in diverse species, including a known pathogen. We find that bacterial RTs prefer pyrimidine nucleotide-linked 6-deoxysugars, not those containing a C6-hydroxyl, as donors. While glycolipid acceptors must contain a lipid, isoprenoid chain length, and stereochemistry can vary. Based on these observations, we demonstrate that a 6-deoxysugar transition state analog inhibits an RT in vitro and reduces levels of RT-dependent O-antigen polysaccharides in Gram-negative cells. As O-antigens are virulence factors, bacteria-specific sugar transferase inhibition represents a novel strategy to prevent bacterial infections.
Collapse
Affiliation(s)
- Alexa P Harnagel
- Department of Chemistry, New York University, New York, New York 10003, United States
| | - Mia Sheshova
- Department of Chemistry, New York University, New York, New York 10003, United States
| | - Meng Zheng
- Department of Chemistry, New York University, New York, New York 10003, United States
| | - Maggie Zheng
- Department of Chemistry, New York University, New York, New York 10003, United States
| | | | - Ewa Swiezewska
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Warsaw, 02-106, Poland
| | - Tania J Lupoli
- Department of Chemistry, New York University, New York, New York 10003, United States
| |
Collapse
|
3
|
Li S, Chen F, Li Y, Wang L, Li H, Gu G, Li E. Rhamnose-Containing Compounds: Biosynthesis and Applications. MOLECULES (BASEL, SWITZERLAND) 2022; 27:molecules27165315. [PMID: 36014553 PMCID: PMC9415975 DOI: 10.3390/molecules27165315] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/09/2022] [Revised: 08/12/2022] [Accepted: 08/15/2022] [Indexed: 11/16/2022]
Abstract
Rhamnose-associated molecules are attracting attention because they are present in bacteria but not mammals, making them potentially useful as antibacterial agents. Additionally, they are also valuable for tumor immunotherapy. Thus, studies on the functions and biosynthetic pathways of rhamnose-containing compounds are in progress. In this paper, studies on the biosynthetic pathways of three rhamnose donors, i.e., deoxythymidinediphosphate-L-rhamnose (dTDP-Rha), uridine diphosphate-rhamnose (UDP-Rha), and guanosine diphosphate rhamnose (GDP-Rha), are firstly reviewed, together with the functions and crystal structures of those associated enzymes. Among them, dTDP-Rha is the most common rhamnose donor, and four enzymes, including glucose-1-phosphate thymidylyltransferase RmlA, dTDP-Glc-4,6-dehydratase RmlB, dTDP-4-keto-6-deoxy-Glc-3,5-epimerase RmlC, and dTDP-4-keto-Rha reductase RmlD, are involved in its biosynthesis. Secondly, several known rhamnosyltransferases from Geobacillus stearothermophilus, Saccharopolyspora spinosa, Mycobacterium tuberculosis, Pseudomonas aeruginosa, and Streptococcus pneumoniae are discussed. In these studies, however, the functions of rhamnosyltransferases were verified by employing gene knockout and radiolabeled substrates, which were almost impossible to obtain and characterize the products of enzymatic reactions. Finally, the application of rhamnose-containing compounds in disease treatments is briefly described.
Collapse
Affiliation(s)
- Siqiang Li
- School of Biological and Food Processing Engineering, Huanghuai University, Zhumadian 463000, China
- Institute of Agricultural Products Fermentation Engineering and Application, Huanghuai University, Zhumadian 463000, China
| | - Fujia Chen
- School of Biological and Food Processing Engineering, Huanghuai University, Zhumadian 463000, China
- Institute of Agricultural Products Fermentation Engineering and Application, Huanghuai University, Zhumadian 463000, China
| | - Yun Li
- School of Biological and Food Processing Engineering, Huanghuai University, Zhumadian 463000, China
- Institute of Agricultural Products Fermentation Engineering and Application, Huanghuai University, Zhumadian 463000, China
| | - Lizhen Wang
- Biology Institute, Qilu University of Technology (Shandong Academy of Sciences), Jinan 250100, China
| | - Hongyan Li
- School of Biological and Food Processing Engineering, Huanghuai University, Zhumadian 463000, China
| | - Guofeng Gu
- National Glycoengineering Research Center, Shandong Key Laboratory of Carbohydrate Chemistry and Glycobiology, Shandong University, 72 Binhai Road, Qingdao 266237, China
- Correspondence: (G.G.); (E.L.)
| | - Enzhong Li
- School of Biological and Food Processing Engineering, Huanghuai University, Zhumadian 463000, China
- Institute of Agricultural Products Fermentation Engineering and Application, Huanghuai University, Zhumadian 463000, China
- Correspondence: (G.G.); (E.L.)
| |
Collapse
|
4
|
Chen WA, Li HY, Sayyad A, Huang CY, Cheng WC. Synthesis of Nitrone-derived Pyrrolidine Scaffolds and Their Combinatorial Libraries to Develop Selective α-l-Rhamnosidase Inhibitors. Chem Asian J 2022; 17:e202200172. [PMID: 35535638 DOI: 10.1002/asia.202200172] [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: 02/23/2022] [Revised: 04/28/2022] [Indexed: 11/06/2022]
Abstract
A general and flexible approach toward the development of α-l-rhamnosidase (α-l-Rha-ase) inhibitors is described. Five enantiopure poly-substituted pyrrolidine-based scaffolds bearing the C1-aminomethyl moiety were designed and synthesized from five-membered cyclic nitrones. Each structurally diversified amide library of these scaffolds was rapidly generated via combinatorial parallel synthesis and applied for in-situ inhibition study against α-l-Rha-ase, allowing us to efficiently identify new inhibition hits. Surprisingly, all promising inhibitors are derived from the same scaffold 3. Among them, the most potent and selective inhibitor is pyrrolidine 19 with Ki =0.24 μM, approximately 24-fold more potent than the reference compound DAA (Ki =5.7 μM). It is the first study to comprehensively prepare pyrrolidine-based scaffolds and libraries for inhibition study against α-l-Rha-ase.
Collapse
Affiliation(s)
- Wei-An Chen
- Genomics Research Centre, Academia Sinica, 128, Section 2, Academia Road, 11529, Taipei, Taiwan
| | - Huang-Yi Li
- Genomics Research Centre, Academia Sinica, 128, Section 2, Academia Road, 11529, Taipei, Taiwan
| | - Ashik Sayyad
- Genomics Research Centre, Academia Sinica, 128, Section 2, Academia Road, 11529, Taipei, Taiwan
| | - Chun-Yen Huang
- Genomics Research Centre, Academia Sinica, 128, Section 2, Academia Road, 11529, Taipei, Taiwan
| | - Wei-Chieh Cheng
- Genomics Research Centre, Academia Sinica, 128, Section 2, Academia Road, 11529, Taipei, Taiwan
- Department of Chemistry, National Cheng-Kung University, 1, University Road, 701, Tainan, Taiwan
- Department of Applied Chemistry, National Chiayi University, 300, Xuefu Rd., East Dist., 600, Chiayi, Taiwan
- Department of Medicinal and Applied Chemistry, Kaohsiung Medical University, 100 Shih-Chuan 1st Rd., 807, Kaohsiung, Taiwan
| |
Collapse
|
5
|
Glycoconjugate pathway connections revealed by sequence similarity network analysis of the monotopic phosphoglycosyl transferases. Proc Natl Acad Sci U S A 2021; 118:2018289118. [PMID: 33472976 DOI: 10.1073/pnas.2018289118] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The monotopic phosphoglycosyl transferase (monoPGT) superfamily comprises over 38,000 nonredundant sequences represented in bacterial and archaeal domains of life. Members of the superfamily catalyze the first membrane-committed step in en bloc oligosaccharide biosynthetic pathways, transferring a phosphosugar from a soluble nucleoside diphosphosugar to a membrane-resident polyprenol phosphate. The singularity of the monoPGT fold and its employment in the pivotal first membrane-committed step allows confident assignment of both protein and corresponding pathway. The diversity of the family is revealed by the generation and analysis of a sequence similarity network for the superfamily, with fusion of monoPGTs with other pathway members being the most frequent and extensive elaboration. Three common fusions were identified: sugar-modifying enzymes, glycosyl transferases, and regulatory domains. Additionally, unexpected fusions of the monoPGT with members of the polytopic PGT superfamily were discovered, implying a possible evolutionary link through the shared polyprenol phosphate substrate. Notably, a phylogenetic reconstruction of the monoPGT superfamily shows a radial burst of functionalization, with a minority of members comprising only the minimal PGT catalytic domain. The commonality and identity of the fusion partners in the monoPGT superfamily is consistent with advantageous colocalization of pathway members at membrane interfaces.
Collapse
|
6
|
An ABC transporter Wzm-Wzt catalyzes translocation of lipid-linked galactan across the plasma membrane in mycobacteria. Proc Natl Acad Sci U S A 2021; 118:2023663118. [PMID: 33879617 DOI: 10.1073/pnas.2023663118] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Mycobacterium tuberculosis, one of the deadliest pathogens in human history, is distinguished by a unique, multilayered cell wall, which offers the bacterium a high level of protection from the attacks of the host immune system. The primary structure of the cell wall core, composed of covalently linked peptidoglycan, branched heteropolysaccharide arabinogalactan, and mycolic acids, is well known, and numerous enzymes involved in the biosynthesis of its components are characterized. The cell wall biogenesis takes place at both cytoplasmic and periplasmic faces of the plasma membrane, and only recently some of the specific transport systems translocating the metabolic intermediates between these two compartments have been characterized [M. Jackson, C. M. Stevens, L. Zhang, H. I. Zgurskaya, M. Niederweis, Chem. Rev., 10.1021/acs.chemrev.0c00869 (2020)]. In this work, we use CRISPR interference methodology in Mycobacterium smegmatis to functionally characterize an ATP-binding cassette (ABC) transporter involved in the translocation of galactan precursors across the plasma membrane. We show that genetic knockdown of the transmembrane subunit of the transporter results in severe morphological changes and the accumulation of an aberrantly long galactan precursor. Based on similarities with structures and functions of specific O-antigen ABC transporters of gram-negative bacteria [C. Whitfield, D. M. Williams, S. D. Kelly, J. Biol. Chem. 295, 10593-10609 (2020)], we propose a model for coupled synthesis and export of the galactan polymer precursor in mycobacteria.
Collapse
|
7
|
Wagstaff BA, Zorzoli A, Dorfmueller HC. NDP-rhamnose biosynthesis and rhamnosyltransferases: building diverse glycoconjugates in nature. Biochem J 2021; 478:685-701. [PMID: 33599745 DOI: 10.1042/bcj20200505] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 01/25/2021] [Accepted: 01/26/2021] [Indexed: 11/17/2022]
Abstract
Rhamnose is an important 6-deoxy sugar present in many natural products, glycoproteins, and structural polysaccharides. Whilst predominantly found as the l-enantiomer, instances of d-rhamnose are also found in nature, particularly in the Pseudomonads bacteria. Interestingly, rhamnose is notably absent from humans and other animals, which poses unique opportunities for drug discovery targeted towards rhamnose utilizing enzymes from pathogenic bacteria. Whilst the biosynthesis of nucleotide-activated rhamnose (NDP-rhamnose) is well studied, the study of rhamnosyltransferases that synthesize rhamnose-containing glycoconjugates is the current focus amongst the scientific community. In this review, we describe where rhamnose has been found in nature, as well as what is known about TDP-β-l-rhamnose, UDP-β-l-rhamnose, and GDP-α-d-rhamnose biosynthesis. We then focus on examples of rhamnosyltransferases that have been characterized using both in vivo and in vitro approaches from plants and bacteria, highlighting enzymes where 3D structures have been obtained. The ongoing study of rhamnose and rhamnosyltransferases, in particular in pathogenic organisms, is important to inform future drug discovery projects and vaccine development.
Collapse
Affiliation(s)
- Ben A Wagstaff
- Manchester Institute of Biotechnology, University of Manchester, 131 Princess Street, Manchester, U.K
- Division of Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, U.K
| | - Azul Zorzoli
- Division of Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, U.K
| | - Helge C Dorfmueller
- Division of Molecular Microbiology, School of Life Sciences, University of Dundee, Dundee DD1 5EH, U.K
| |
Collapse
|
8
|
LytR-CpsA-Psr Glycopolymer Transferases: Essential Bricks in Gram-Positive Bacterial Cell Wall Assembly. Int J Mol Sci 2021; 22:ijms22020908. [PMID: 33477538 PMCID: PMC7831098 DOI: 10.3390/ijms22020908] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 01/14/2021] [Accepted: 01/14/2021] [Indexed: 12/28/2022] Open
Abstract
The cell walls of Gram-positive bacteria contain a variety of glycopolymers (CWGPs), a significant proportion of which are covalently linked to the peptidoglycan (PGN) scaffolding structure. Prominent CWGPs include wall teichoic acids of Staphylococcus aureus, streptococcal capsules, mycobacterial arabinogalactan, and rhamnose-containing polysaccharides of lactic acid bacteria. CWGPs serve important roles in bacterial cellular functions, morphology, and virulence. Despite evident differences in composition, structure and underlaying biosynthesis pathways, the final ligation step of CWGPs to the PGN backbone involves a conserved class of enzymes-the LytR-CpsA-Psr (LCP) transferases. Typically, the enzymes are present in multiple copies displaying partly functional redundancy and/or preference for a distinct CWGP type. LCP enzymes require a lipid-phosphate-linked glycan precursor substrate and catalyse, with a certain degree of promiscuity, CWGP transfer to PGN of different maturation stages, according to in vitro evidence. The prototype attachment mode is that to the C6-OH of N-acetylmuramic acid residues via installation of a phosphodiester bond. In some cases, attachment proceeds to N-acetylglucosamine residues of PGN-in the case of the Streptococcus agalactiae capsule, even without involvement of a phosphate bond. A novel aspect of LCP enzymes concerns a predicted role in protein glycosylation in Actinomyces oris. Available crystal structures provide further insight into the catalytic mechanism of this biologically important class of enzymes, which are gaining attention as new targets for antibacterial drug discovery to counteract the emergence of multidrug resistant bacteria.
Collapse
|
9
|
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.
Collapse
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
| |
Collapse
|
10
|
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: 50] [Impact Index Per Article: 12.5] [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.
Collapse
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.
| |
Collapse
|
11
|
Madani A, Ridenour JN, Martin BP, Paudel RR, Abdul Basir A, Le Moigne V, Herrmann JL, Audebert S, Camoin L, Kremer L, Spilling CD, Canaan S, Cavalier JF. Cyclipostins and Cyclophostin Analogues as Multitarget Inhibitors That Impair Growth of Mycobacterium abscessus. ACS Infect Dis 2019; 5:1597-1608. [PMID: 31299146 DOI: 10.1021/acsinfecdis.9b00172] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Twelve new Cyclophostin and Cyclipostins analogues (CyC19-30) were synthesized, thus extending our series to 38 CyCs. Their antibacterial activities were evaluated against four pathogenic mycobacteria (Mycobacterium abscessus, Mycobacterium marinum, Mycobacterium bovis BCG, and Mycobacterium tuberculosis) and two Gram negative bacteria. The CyCs displayed very low toxicity toward host cells and were only active against mycobacteria. Importantly, several CyCs were active against extracellular M. abscessus (CyC17/CyC18β/CyC25/CyC26) or intramacrophage residing mycobacteria (CyC7(α,β)/CyC8(α,β)) with minimal inhibitory concentrations (MIC50) values comparable to or better than those of amikacin or imipenem, respectively. An activity-based protein profiling combined with mass spectrometry allowed identification of the potential target enzymes of CyC17/CyC26, mostly being involved in lipid metabolism and/or in cell wall biosynthesis. Overall, these results strengthen the selective activity of the CyCs against mycobacteria, including the most drug-resistant M. abscessus, through the cumulative inhibition of a large number of Ser- and Cys-enzymes participating in key physiological processes.
Collapse
Affiliation(s)
- Abdeldjalil Madani
- Aix-Marseille Université, CNRS, LISM, Institut de Microbiologie de la Méditerranée, Marseille, France 13402 Cedex 20
| | - Jeremy N. Ridenour
- Department of Chemistry and Biochemistry, University of Missouri−St. Louis, One University Boulevard, St. Louis, Missouri 63121, United States
| | - Benjamin P. Martin
- Department of Chemistry and Biochemistry, University of Missouri−St. Louis, One University Boulevard, St. Louis, Missouri 63121, United States
| | - Rishi R. Paudel
- Department of Chemistry and Biochemistry, University of Missouri−St. Louis, One University Boulevard, St. Louis, Missouri 63121, United States
| | - Anosha Abdul Basir
- Department of Chemistry and Biochemistry, University of Missouri−St. Louis, One University Boulevard, St. Louis, Missouri 63121, United States
| | - Vincent Le Moigne
- APHP, GHU PIFO, Hôpital Raymond-Poincaré−Hôpital Ambroise-Paré, 92100 Boulogne-Billancourt, France
| | - Jean-Louis Herrmann
- APHP, GHU PIFO, Hôpital Raymond-Poincaré−Hôpital Ambroise-Paré, 92100 Boulogne-Billancourt, France
- 2I, UVSQ, INSERM UMR 1173, Université Paris-Saclay, 78035 Versailles, France
| | - Stéphane Audebert
- Aix Marseille Université, CNRS, INSERM, Institut Paoli-Calmettes, CRCM, Marseille Protéomique, 13273 Marseille Cedex 09, France
| | - Luc Camoin
- Aix Marseille Université, CNRS, INSERM, Institut Paoli-Calmettes, CRCM, Marseille Protéomique, 13273 Marseille Cedex 09, France
| | - Laurent Kremer
- Institut de Recherche en Infectiologie de Montpellier (IRIM), CNRS, UMR 9004, Université de Montpellier, 34293 Montpellier, France
- IRIM, INSERM, 34293 Montpellier, France
| | - Christopher D. Spilling
- Department of Chemistry and Biochemistry, University of Missouri−St. Louis, One University Boulevard, St. Louis, Missouri 63121, United States
| | - Stéphane Canaan
- Aix-Marseille Université, CNRS, LISM, Institut de Microbiologie de la Méditerranée, Marseille, France 13402 Cedex 20
| | - Jean-François Cavalier
- Aix-Marseille Université, CNRS, LISM, Institut de Microbiologie de la Méditerranée, Marseille, France 13402 Cedex 20
| |
Collapse
|
12
|
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.
Collapse
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.
| |
Collapse
|
13
|
Puffal J, García-Heredia A, Rahlwes KC, Siegrist MS, Morita YS. Spatial control of cell envelope biosynthesis in mycobacteria. Pathog Dis 2018; 76:4953754. [DOI: 10.1093/femspd/fty027] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Accepted: 03/25/2018] [Indexed: 11/12/2022] Open
Affiliation(s)
- Julia Puffal
- Department of Microbiology, University of Massachusetts, Amherst, MA 01003, USA
| | - Alam García-Heredia
- Molecular and Cellular Biology Graduate Program, University of Massachusetts, Amherst, MA 01003, USA
| | - Kathryn C Rahlwes
- Department of Microbiology, University of Massachusetts, Amherst, MA 01003, USA
| | - M Sloan Siegrist
- Department of Microbiology, University of Massachusetts, Amherst, MA 01003, USA
- Molecular and Cellular Biology Graduate Program, University of Massachusetts, Amherst, MA 01003, USA
| | - Yasu S Morita
- Department of Microbiology, University of Massachusetts, Amherst, MA 01003, USA
- Molecular and Cellular Biology Graduate Program, University of Massachusetts, Amherst, MA 01003, USA
| |
Collapse
|
14
|
N-Acetylglucosamine-1-Phosphate Transferase, WecA, as a Validated Drug Target in Mycobacterium tuberculosis. Antimicrob Agents Chemother 2017; 61:AAC.01310-17. [PMID: 28874370 DOI: 10.1128/aac.01310-17] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2017] [Accepted: 08/25/2017] [Indexed: 12/24/2022] Open
Abstract
The mycobacterial phosphoglycosyltransferase WecA, which initiates arabinogalactan biosynthesis in Mycobacterium tuberculosis, has been proposed as a target of the caprazamycin derivative CPZEN-45, a preclinical drug candidate for the treatment of tuberculosis. In this report, we describe the functional characterization of mycobacterial WecA and confirm the essentiality of its encoding gene in M. tuberculosis by demonstrating that the transcriptional silencing of wecA is bactericidal in vitro and in macrophages. Silencing wecA also conferred hypersensitivity of M. tuberculosis to the drug tunicamycin, confirming its target selectivity for WecA in whole cells. Simple radiometric assays performed with mycobacterial membranes and commercially available substrates allowed chemical validation of other putative WecA inhibitors and resolved their selectivity toward WecA versus another attractive cell wall target, translocase I, which catalyzes the first membrane step in the biosynthesis of peptidoglycan. These assays and the mutant strain described herein will be useful for identifying potential antitubercular leads by screening chemical libraries for novel WecA inhibitors.
Collapse
|
15
|
Nasiri MJ, Haeili M, Ghazi M, Goudarzi H, Pormohammad A, Imani Fooladi AA, Feizabadi MM. New Insights in to the Intrinsic and Acquired Drug Resistance Mechanisms in Mycobacteria. Front Microbiol 2017; 8:681. [PMID: 28487675 PMCID: PMC5403904 DOI: 10.3389/fmicb.2017.00681] [Citation(s) in RCA: 82] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2016] [Accepted: 04/04/2017] [Indexed: 01/25/2023] Open
Abstract
Infectious diseases caused by clinically important Mycobacteria continue to be an important public health problem worldwide primarily due to emergence of drug resistance crisis. In recent years, the control of tuberculosis (TB), the disease caused by Mycobacterium tuberculosis (MTB), is hampered by the emergence of multidrug resistance (MDR), defined as resistance to at least isoniazid (INH) and rifampicin (RIF), two key drugs in the treatment of the disease. Despite the availability of curative anti-TB therapy, inappropriate and inadequate treatment has allowed MTB to acquire resistance to the most important anti-TB drugs. Likewise, for most mycobacteria other than MTB, the outcome of drug treatment is poor and is likely related to the high levels of antibiotic resistance. Thus, a better knowledge of the underlying mechanisms of drug resistance in mycobacteria could aid not only to select the best therapeutic options but also to develop novel drugs that can overwhelm the existing resistance mechanisms. In this article, we review the distinctive mechanisms of antibiotic resistance in mycobacteria.
Collapse
Affiliation(s)
- Mohammad J. Nasiri
- Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical SciencesTehran, Iran
| | - Mehri Haeili
- Department of Biology, Faculty of Natural Sciences, University of TabrizTabriz, Iran
| | - Mona Ghazi
- Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical SciencesTehran, Iran
| | - Hossein Goudarzi
- Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical SciencesTehran, Iran
| | - Ali Pormohammad
- Department of Microbiology, School of Medicine, Shahid Beheshti University of Medical SciencesTehran, Iran
| | - Abbas A. Imani Fooladi
- Applied Microbiology Research Center, Baqiyatallah University of Medical SciencesTehran, Iran
| | - Mohammad M. Feizabadi
- Department of Microbiology, School of Medicine, Tehran University of Medical SciencesTehran, Iran
- Thoracic Research Center, Imam Khomeini Hospital, Tehran University of Medical SciencesTehran, Iran
| |
Collapse
|
16
|
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.
Collapse
|
17
|
Poulin MB, Lowary TL. Chemical Insight into the Mechanism and Specificity of GlfT2, a Bifunctional Galactofuranosyltransferase from Mycobacteria. J Org Chem 2016; 81:8123-30. [PMID: 27557056 DOI: 10.1021/acs.joc.6b01501] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Mycobacteria, including the human pathogen Mycobacterium tuberculosis, produce a complex cell wall structure that is essential to survival. A key component of this structure is a glycoconjugate, the mycolyl-arabinogalactan-peptidoglycan complex, which has at its core a galactan domain composed of galactofuranose (Galf) residues linked to peptidoglycan. Because galactan biosynthesis is essential for mycobacterial viability, compounds that interfere with this process are potential therapeutic agents for treating mycobacterial diseases, including tuberculosis. Galactan biosynthesis in mycobacteria involves two glycosyltransferases, GlfT1 and GlfT2, which have been the subject of increasing interest in recent years. This Synopsis summarizes efforts to characterize the mechanism and specificity of GlfT2, which is responsible for introducing the majority of the Galf residues into mycobacterial galactan.
Collapse
Affiliation(s)
- Myles B Poulin
- Alberta Glycomics Centre and Department of Chemistry, University of Alberta , 11227 Saskatchewan Drive, Edmonton, Alberta T6G 2G2, Canada
| | - Todd L Lowary
- Alberta Glycomics Centre and Department of Chemistry, University of Alberta , 11227 Saskatchewan Drive, Edmonton, Alberta T6G 2G2, Canada
| |
Collapse
|
18
|
Lcp1 Is a Phosphotransferase Responsible for Ligating Arabinogalactan to Peptidoglycan in Mycobacterium tuberculosis. mBio 2016; 7:mBio.00972-16. [PMID: 27486192 PMCID: PMC4981717 DOI: 10.1128/mbio.00972-16] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
UNLABELLED Mycobacterium tuberculosis, the etiological agent of tuberculosis (TB), has a unique cell envelope which accounts for its unusual low permeability and contributes to resistance against common antibiotics. The main structural elements of the cell wall consist of a cross-linked network of peptidoglycan (PG) in which some of the muramic acid residues are covalently attached to a complex polysaccharide, arabinogalactan (AG), via a unique α-l-rhamnopyranose-(1→3)-α-d-GlcNAc-(1→P) linker unit. While the molecular genetics associated with PG and AG biosynthetic pathways have been largely delineated, the mechanism by which these two major pathways converge has remained elusive. In Gram-positive organisms, the LytR-CpsA-Psr (LCP) family of proteins are responsible for ligating cell wall teichoic acids to peptidoglycan, through a linker unit that bears a striking resemblance to that found in mycobacterial arabinogalactan. In this study, we have identified Rv3267 as a mycobacterial LCP homolog gene that encodes a phosphotransferase which we have named Lcp1. We demonstrate that lcp1 is an essential gene required for cell viability and show that recombinant Lcp1 is capable of ligating AG to PG in a cell-free radiolabeling assay. IMPORTANCE Tuberculosis is an infectious disease caused by the bacterial organism Mycobacterium tuberculosis Survival of M. tuberculosis rests critically on the integrity of its unique cell wall; therefore, a better understanding of how the genes and enzymes involved in cell wall assembly work is fundamental for us to develop new drugs to treat this disease. In this study, we have identified Lcp1 as an essential phosphotransferase that ligates together arabinogalactan and peptidoglycan, two crucial cell wall macromolecules found within the mycobacterial cell wall. The discovery of Lcp1 sheds new light on the final stages of mycobacterial cell wall assembly and represents a key biosynthetic step that could be exploited for new anti-TB drug discovery.
Collapse
|
19
|
Raju G, Rao MV, Rao BV. Concise stereoselective synthesis of 5-hydroxy carba-β-D-rhamnose, carba-β-D-rhamnose, (-)-gabosine O, and carba-α-D-rhamnose. J Carbohydr Chem 2016. [DOI: 10.1080/07328303.2016.1170138] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Gurrapu Raju
- Organic and Biomolecular Chemistry Division, CSIR-Indian Institute of Chemical Technology, Hyderabad, Telangana, India
| | - Maddimsetti Venkateswara Rao
- Organic and Biomolecular Chemistry Division, CSIR-Indian Institute of Chemical Technology, Hyderabad, Telangana, India
| | - Batchu Venkateswara Rao
- Organic and Biomolecular Chemistry Division, CSIR-Indian Institute of Chemical Technology, Hyderabad, Telangana, India
| |
Collapse
|
20
|
Wang M, Arbatsky NP, Xu L, Shashkov AS, Wang L, Knirel YA. O antigen of FranconibacterpulverisG3872 (O1) is a 4-deoxy-d-arabino-hexose-containing polysaccharide synthesized by the ABC-transporter-dependent pathway. MICROBIOLOGY-SGM 2016; 162:1103-1113. [PMID: 27166227 DOI: 10.1099/mic.0.000307] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Franconibacter (Enterobacter, Cronobacter) pulveris bacteria share several typical characteristics with, and hence pose a challenge for the detection of, Cronobacter sakazakii, an emerging opportunistic pathogen, which can cause severe infections in neonates. A structurally variable O-specific polysaccharide (OPS) called O antigen provides the major basis for the typing of Gram-negative bacteria. We investigated the structure and genetics of the O antigen of F. pulveris G3872 (designated O1). An OPS was isolated by mild alkaline degradation of the LPS, whereas the same polysaccharide and its oligosaccharide fragments were obtained by mild acid degradation. Studies by sugar analysis and NMR spectroscopy showed that the OPS contained d-ribose, l-rhamnose (l-Rha) and a rarely occurring monosaccharide 4-deoxy-d-arabino-hexose, and the OPS structure was established. The O-antigen gene cluster of F. pulveris G3872 between JUMPStart and gnd genes includes putative genes for glycosyltransferases, ATP-binding cassette (ABC)-transporter genes wzm and wzt, and genes for the synthesis of l-Rha, but no genes for the synthesis of 4-deoxy-d-arabino-hexose. A mutation test with the wzm gene confirmed that the OPS is synthesized and exported by the ABC-transporter-dependent pathway. A trifunctional transferase was suggested to catalyse formation of two glycosidic linkages and add a methyl group to the non-reducing end of the OPS to terminate the chain elongation. A carbohydrate-binding module that presumably recognizes the terminal methyl-modified monosaccharide was found at the C-terminus of Wzt. Primers specific for F. pulveris G3872 were designed based on the wzm gene, which has potential to be used for identification and detection of the O1 serogroup.
Collapse
Affiliation(s)
- Min Wang
- TEDA School of Biological Sciences and Biotechnology, Nankai University, TEDA, 300457 Tianjin, China.,Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, 300071 Tianjin, China
| | - Nikolay P Arbatsky
- N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 119991 Moscow, Russia
| | - Lingling Xu
- TEDA School of Biological Sciences and Biotechnology, Nankai University, TEDA, 300457 Tianjin, China.,Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, 300071 Tianjin, China
| | - Alexander S Shashkov
- N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 119991 Moscow, Russia
| | - Lei Wang
- TEDA School of Biological Sciences and Biotechnology, Nankai University, TEDA, 300457 Tianjin, China.,Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, 300071 Tianjin, China
| | - Yuriy A Knirel
- N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, 119991 Moscow, Russia
| |
Collapse
|
21
|
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.
Collapse
|
22
|
Inhibition of Mycobacterium-RmlA by Molecular Modeling, Dynamics Simulation, and Docking. Adv Bioinformatics 2016; 2016:9841250. [PMID: 26981117 PMCID: PMC4769735 DOI: 10.1155/2016/9841250] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Revised: 12/12/2015] [Accepted: 12/24/2015] [Indexed: 11/17/2022] Open
Abstract
The increasing resistance to anti-tb drugs has enforced strategies for finding new drug targets against Mycobacterium tuberculosis (Mtb). In recent years enzymes associated with the rhamnose pathway in Mtb have attracted attention as drug targets. The present work is on α-D-glucose-1-phosphate thymidylyltransferase (RmlA), the first enzyme involved in the biosynthesis of L-rhamnose, of Mtb cell wall. This study aims to derive a 3D structure of RmlA by using a comparative modeling approach. Structural refinement and energy minimization of the built model have been done with molecular dynamics. The reliability assessment of the built model was carried out with various protein checking tools such as Procheck, Whatif, ProsA, Errat, and Verify 3D. The obtained model investigates the relation between the structure and function. Molecular docking interactions of Mtb-RmlA with modified EMB (ethambutol) ligands and natural substrate have revealed specific key residues Arg13, Lys23, Asn109, and Thr223 which play an important role in ligand binding and selection. Compared to all EMB ligands, EMB-1 has shown better interaction with Mtb-RmlA model. The information thus discussed above will be useful for the rational design of safe and effective inhibitors specific to RmlA enzyme pertaining to the treatment of tuberculosis.
Collapse
|
23
|
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.
Collapse
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
| | | |
Collapse
|
24
|
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;
| |
Collapse
|
25
|
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.
Collapse
Affiliation(s)
- Monika Jankute
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | | | | | | |
Collapse
|
26
|
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.
Collapse
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
| |
Collapse
|
27
|
The Complex Mechanism of Antimycobacterial Action of 5-Fluorouracil. ACTA ACUST UNITED AC 2015; 22:63-75. [DOI: 10.1016/j.chembiol.2014.11.006] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Revised: 10/30/2014] [Accepted: 11/03/2014] [Indexed: 11/17/2022]
|
28
|
Woo SH, Park SI. Effects of phosphoglucomutase gene (PGM) in Streptococcus parauberis on innate immune response and pathogenicity of olive flounder (Paralichthys olivaceus). FISH & SHELLFISH IMMUNOLOGY 2014; 41:317-325. [PMID: 25240979 DOI: 10.1016/j.fsi.2014.09.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2014] [Revised: 08/26/2014] [Accepted: 09/10/2014] [Indexed: 06/03/2023]
Abstract
In recent years, Streptococcus parauberis infection has been an emerging problem in aquaculture in South Korea because of its more frequent isolation than other streptococcal bacteria including Streptococcus iniae. To develop effective treatment and prophylaxis methods against this emerging disease by S. parauberis, it is necessary to understand the underlying pathogenic mechanisms. To uncover the pathogenicity, the mutant strain of S. parauberis with a deleted phosphoglucomutase (PGM) gene which has been known to be an important virulence factor in bacterial pathogens was generated to investigate the relationship between virulence and gene function using an allelic exchange mutagenesis method. Allelic exchange mutagenesis of the phosphoglucomutase gene resulted in phenotype changes including decreased extracellular capsules, reduced buoyancy, increased hydrophobicity and reduced growth. Moreover, the S. parauberis mutant was more sensitive to innate immune clearance mechanisms including serum, mucus and phagocyte killing and could not induce mortality in olive flounder. These phenotype changes and the attenuated virulence of the pathogen to fish could be due to the reduction in capsule production by mutation of the PGM gene. The results provide evidences that phosphoglucomutase expression contributes to S. parauberis virulence in fish by affecting bacterial survival against the host's humoral and cellular defense mechanisms.
Collapse
Affiliation(s)
- Sung Ho Woo
- Institute of Fisheries Sciences, Pukyong National University, 474, Ilgwang-Ro, Ilgwang-myeon, Gijang-gun, Busan 619-911, South Korea; Department of Aquatic Life Medicine, Pukyong National University, 45, Yongso-ro, Namgu, Busan 608-737, South Korea.
| | - Soo Il Park
- Department of Aquatic Life Medicine, Pukyong National University, 45, Yongso-ro, Namgu, Busan 608-737, South Korea.
| |
Collapse
|
29
|
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.
Collapse
Affiliation(s)
- Shiva Kumar Angala
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University , Fort Collins, CO , USA
| | | | | | | | | |
Collapse
|
30
|
Alibaud L, Pawelczyk J, Gannoun-Zaki L, Singh VK, Rombouts Y, Drancourt M, Dziadek J, Guérardel Y, Kremer L. Increased phagocytosis of Mycobacterium marinum mutants defective in lipooligosaccharide production: a structure-activity relationship study. J Biol Chem 2013; 289:215-28. [PMID: 24235141 DOI: 10.1074/jbc.m113.525550] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mycobacterium marinum is a waterborne pathogen responsible for tuberculosis-like infections in ectotherms and is an occasional opportunistic human pathogen. In the environment, M. marinum also interacts with amoebae, which may serve as a natural reservoir for this microorganism. However, the description of mycobacterial determinants in the early interaction with macrophages or amoebae remains elusive. Lipooligosaccharides (LOSs) are cell surface-exposed glycolipids capable of modulating the host immune system, suggesting that they may be involved in the early interactions of M. marinum with macrophages. Herein, we addressed whether LOS composition affects the uptake of M. marinum by professional phagocytes. Mutants with various truncated LOS variants were generated, leading to the identification of several previously uncharacterized biosynthetic genes (wbbL2, MMAR_2321, and MMAR_2331). Biochemical and structural approaches allowed resolving the structures of LOS precursors accumulating in this set of mutants. These strains with structurally defined LOS profiles were then used to infect both macrophages and Acanthamoebae. An inverse correlation between LOS completeness and uptake of mycobacteria by phagocytes was found, allowing the proposal of three mutant classes: class I (papA4), devoid of LOS and highly efficiently phagocytosed; class II, accumulating only early LOS intermediates (wbbL2 and MMAR_2331) and efficiently phagocytosed but less than class I mutants; class III, lacking LOS-IV (losA, MMAR_2319, and MMAR_2321) and phagocytosed similarly to the control strain. These results indicate that phagocytosis is conditioned by the LOS pattern and that the LOS pathway used by M. marinum in macrophages is conserved during infection of amoebae.
Collapse
Affiliation(s)
- Laeticia Alibaud
- From the Laboratoire de Dynamique des Interactions Membranaires Normales et Pathologiques, Université de Montpellier 2 et 1, CNRS, UMR 5235, case 107, Place Eugène Bataillon, 34095 Montpellier Cedex 05, France
| | | | | | | | | | | | | | | | | |
Collapse
|
31
|
Inactivation of the phosphoglucomutase gene pgm in Corynebacterium glutamicum affects cell shape and glycogen metabolism. Biosci Rep 2013; 33:BSR20130076. [PMID: 23863124 PMCID: PMC3755335 DOI: 10.1042/bsr20130076] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
In Corynebacterium glutamicum formation of glc-1-P (α-glucose-1-phosphate) from glc-6-P (glucose-6-phosphate) by α-Pgm (phosphoglucomutase) is supposed to be crucial for synthesis of glycogen and the cell wall precursors trehalose and rhamnose. Furthermore, Pgm is probably necessary for glycogen degradation and maltose utilization as glucan phosphorylases of both pathways form glc-1-P. We here show that C. glutamicum possesses at least two Pgm isoenzymes, the cg2800 (pgm) encoded enzyme contributing most to total Pgm activity. By inactivation of pgm we created C. glutamicum IMpgm showing only about 12% Pgm activity when compared to the parental strain. We characterized both strains during cultivation with either glucose or maltose as substrate and observed that (i) the glc-1-P content in the WT (wild-type) and the mutant remained constant independent of the carbon source used, (ii) the glycogen levels in the pgm mutant were lower during growth on glucose and higher during growth on maltose, and (iii) the morphology of the mutant was altered with maltose as a substrate. We conclude that C. glutamicum employs glycogen as carbon capacitor to perform glc-1-P homeostasis in the exponential growth phase and is therefore able to counteract limited Pgm activity for both anabolic and catabolic metabolic pathways.
Collapse
|
32
|
Alphey MS, Pirrie L, Torrie LS, Boulkeroua WA, Gardiner M, Sarkar A, Maringer M, Oehlmann W, Brenk R, Scherman MS, McNeil M, Rejzek M, Field RA, Singh M, Gray D, Westwood NJ, Naismith JH. Allosteric competitive inhibitors of the glucose-1-phosphate thymidylyltransferase (RmlA) from Pseudomonas aeruginosa. ACS Chem Biol 2013; 8:387-96. [PMID: 23138692 DOI: 10.1021/cb300426u] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Glucose-1-phosphate thymidylyltransferase (RmlA) catalyzes the condensation of glucose-1-phosphate (G1P) with deoxy-thymidine triphosphate (dTTP) to yield dTDP-d-glucose and pyrophosphate. This is the first step in the l-rhamnose biosynthetic pathway. l-Rhamnose is an important component of the cell wall of many microorganisms, including Mycobacterium tuberculosis and Pseudomonas aeruginosa. Here we describe the first nanomolar inhibitors of P. aeruginosa RmlA. These thymine analogues were identified by high-throughput screening and subsequently optimized by a combination of protein crystallography, in silico screening, and synthetic chemistry. Some of the inhibitors show inhibitory activity against M. tuberculosis. The inhibitors do not bind at the active site of RmlA but bind at a second site remote from the active site. Despite this, the compounds act as competitive inhibitors of G1P but with high cooperativity. This novel behavior was probed by structural analysis, which suggests that the inhibitors work by preventing RmlA from undergoing the conformational change key to its ordered bi-bi mechanism.
Collapse
Affiliation(s)
- Magnus S. Alphey
- Biomedical Sciences Research
Complex, University of St. Andrews, St.
Andrews KY16 9ST, U.K
| | - Lisa Pirrie
- Biomedical Sciences Research
Complex, University of St. Andrews, St.
Andrews KY16 9ST, U.K
- School of Chemistry, University of St. Andrews and EaStCHEM, St. Andrews
KY16 9ST, U.K
| | - Leah S. Torrie
- Biological
Chemistry and Drug
Discovery, College of Life Sciences, University of Dundee, Dundee DD1 5EH, U.K
| | | | - Mary Gardiner
- Biological
Chemistry and Drug
Discovery, College of Life Sciences, University of Dundee, Dundee DD1 5EH, U.K
| | - Aurijit Sarkar
- Biological
Chemistry and Drug
Discovery, College of Life Sciences, University of Dundee, Dundee DD1 5EH, U.K
| | - Marko Maringer
- mfd Diagnostics GmbH, Mikroforum Ring 5, 55234 Wendelsheim, Germany
| | - Wulf Oehlmann
- Lionex GmbH, Salzdahlumer Str. 196, 38126 Braunschweig, Germany
| | - Ruth Brenk
- Biological
Chemistry and Drug
Discovery, College of Life Sciences, University of Dundee, Dundee DD1 5EH, U.K
| | - Michael S. Scherman
- Department of Microbiology, Immunology
and Pathology, Colorado State University, 1682 Campus Delivery, Ft. Collins, Colorado 80523-1682, United
States
| | - Michael McNeil
- Department of Microbiology, Immunology
and Pathology, Colorado State University, 1682 Campus Delivery, Ft. Collins, Colorado 80523-1682, United
States
| | - Martin Rejzek
- Department of Biological
Chemistry, John Innes Centre, Norwich NR4
7UH, U.K
| | - Robert A. Field
- Department of Biological
Chemistry, John Innes Centre, Norwich NR4
7UH, U.K
| | - Mahavir Singh
- Lionex GmbH, Salzdahlumer Str. 196, 38126 Braunschweig, Germany
| | - David Gray
- Biological
Chemistry and Drug
Discovery, College of Life Sciences, University of Dundee, Dundee DD1 5EH, U.K
| | - Nicholas J. Westwood
- Biomedical Sciences Research
Complex, University of St. Andrews, St.
Andrews KY16 9ST, U.K
- School of Chemistry, University of St. Andrews and EaStCHEM, St. Andrews
KY16 9ST, U.K
| | - James H. Naismith
- Biomedical Sciences Research
Complex, University of St. Andrews, St.
Andrews KY16 9ST, U.K
| |
Collapse
|
33
|
Mishra AK, Krumbach K, Rittmann D, Batt SM, Lee OYC, De S, Frunzke J, Besra GS, Eggeling L. Deletion of manC in Corynebacterium glutamicum results in a phospho-myo-inositol mannoside- and lipoglycan-deficient mutant. MICROBIOLOGY-SGM 2012; 158:1908-1917. [PMID: 22539165 DOI: 10.1099/mic.0.057653-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Mannose is an important constituent of the immunomodulatory glycoconjugates of the mycobacterial cell wall: lipoarabinomannan (LAM), lipomannan (LM) and the related phospho-myo-inositol mannosides (PIMs). In Mycobacterium tuberculosis and the related bacillus Corynebacterium glutamicum, mannose is either imported from the medium or derived from glycolysis, and is subsequently converted into the nucleotide-based sugar donor guanosine diphosphomannose (GDP-mannose). This can be utilized by the glycosyltranferases of the GT-A/B superfamily or converted to the lipid-based donor polyprenyl monophosphomannose, and used as a substrate by the transmembrane glycosyltransferases of the GT-C superfamily. To investigate GDP-mannose biosynthesis in detail, the gene encoding a putative ManC in C. glutamicum was deleted. Deletion of manC resulted in a slow-growing mutant, with reduced but not totally abrogated guanosine diphosphomannose pyrophosphorylase activity. However, a comprehensive cell wall analysis revealed that C. glutamicumΔmanC is deficient in PIMs and LM/LAM. Closer inspection suggests that promiscuous ManC activity is contributed by additional putative nucleotidyltransferases, PmmB, WbbL1, GalU and GlmU, and a hypothetical protein, NCgl0715. Furthermore, complementation analyses of C. glutamicumΔmanC with Rv3264c suggested that it is a true homologue of ManC in M. tuberculosis, and the essentiality of PIMs in M. tuberculosis makes it an attractive drug target.
Collapse
Affiliation(s)
- Arun K Mishra
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Karin Krumbach
- Biotechnology (IBG-1), Research Centre Juelich GmbH, D-52425 Juelich, Germany
| | - Doris Rittmann
- Biotechnology (IBG-1), Research Centre Juelich GmbH, D-52425 Juelich, Germany
| | - Sarah M Batt
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Oona Y-C Lee
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Sandip De
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Julia Frunzke
- Biotechnology (IBG-1), Research Centre Juelich GmbH, D-52425 Juelich, Germany
| | - Gurdyal S Besra
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | - Lothar Eggeling
- Biotechnology (IBG-1), Research Centre Juelich GmbH, D-52425 Juelich, Germany
| |
Collapse
|
34
|
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.
Collapse
Affiliation(s)
- Monika Jankute
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK
| | | | | | | |
Collapse
|
35
|
Dianišková P, Korduláková J, Skovierová H, Kaur D, Jackson M, Brennan PJ, Mikušová K. Investigation of ABC transporter from mycobacterial arabinogalactan biosynthetic cluster. Gen Physiol Biophys 2011; 30:239-50. [PMID: 21952433 DOI: 10.4149/gpb_2011_03_239] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Two genes from the "mycobacterial arabinogalactan biosynthetic cluster" spanning the region from Rv3779 to Rv3809c in the genome of Mycobacterium tuberculosis H37Rv were annotated as possible components of the ATP-binding cassette transporter. Rv3781 encodes a nucleotide-binding domain and Rv3783 determines production of a membrane-spanning domain. We have examined possible roles of these genes in mycobacterial cell wall biosynthesis through inactivation of their respective orthologs in Mycobacterium smegmatis mc(2)155, phenotypic characterization of the mutant strains via metabolic labeling with [U-(14)C]-glucose, cell-free reactions with UDP-[U-(14)C]-galactose monitoring galactan build-up and transcriptional analysis. Several lines of evidence suggest that this ABC transporter is involved in biosynthesis of arabinogalactan, although more investigation is needed to establish its precise role or the transported substrate.
Collapse
|
36
|
Barry CS, Backus KM, Barry CE, Davis BG. ESI-MS assay of M. tuberculosis cell wall antigen 85 enzymes permits substrate profiling and design of a mechanism-based inhibitor. J Am Chem Soc 2011; 133:13232-5. [PMID: 21776980 PMCID: PMC11042539 DOI: 10.1021/ja204249p] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Mycobacterium tuberculosis Antigen 85 enzymes are vital to the integrity of the highly impermeable cell envelope and are potential therapeutic targets. Kinetic analysis using a label-free assay revealed both mechanistic details and a substrate profile that allowed the design and construction of a selective in vitro mechanism-based inhibitor.
Collapse
Affiliation(s)
- Conor S Barry
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Mansfield Road, Oxford OX1 3TA, UK
| | | | | | | |
Collapse
|
37
|
Peltier P, Beláňová M, Dianišková P, Zhou R, Zheng RB, Pearcey JA, Joe M, Brennan PJ, Nugier-Chauvin C, Ferrières V, Lowary TL, Daniellou R, Mikušová K. Synthetic UDP-furanoses as potent inhibitors of mycobacterial galactan biogenesis. ACTA ACUST UNITED AC 2011; 17:1356-66. [PMID: 21168771 DOI: 10.1016/j.chembiol.2010.10.014] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2010] [Revised: 10/25/2010] [Accepted: 10/27/2010] [Indexed: 11/29/2022]
Abstract
UDP-galactofuranose (UDP-Galf) is a substrate for two types of enzymes, UDP-galactopyranose mutase and galactofuranosyltransferases, which are present in many pathogenic organisms but absent from mammals. In particular, these enzymes are involved in the biosynthesis of cell wall galactan, a polymer essential for the survival of the causative agent of tuberculosis, Mycobacterium tuberculosis. We describe here the synthesis of derivatives of UDP-Galf modified at C-5 and C-6 using a chemoenzymatic route. In cell-free assays, these compounds prevented the formation of mycobacterial galactan, via the production of short "dead-end" intermediates resulting from their incorporation into the growing oligosaccharide chain. Modified UDP-furanoses thus constitute novel probes for the study of the two classes of enzymes involved in mycobacterial galactan assembly, and studies with these compounds may ultimately facilitate the future development of new therapeutic agents against tuberculosis.
Collapse
Affiliation(s)
- Pauline Peltier
- Ecole Nationale Supérieure de Chimie de Rennes, CNRS, UMR 6226, 35708 Rennes, Cedex 7, France
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
38
|
Wu Q, Zhou P, Qian S, Qin X, Fan Z, Fu Q, Zhan Z, Pei H. Cloning, expression, identification and bioinformatics analysis of Rv3265c gene from Mycobacterium tuberculosis in Escherichia coli. ASIAN PAC J TROP MED 2011; 4:266-70. [DOI: 10.1016/s1995-7645(11)60083-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2010] [Revised: 02/14/2011] [Accepted: 03/15/2011] [Indexed: 10/18/2022] Open
|
39
|
Matsuba T, Nakajima C, Suzuki Y. [Envelope structure and components of Mycobacterium tuberculosis]. Nihon Saikingaku Zasshi 2010; 65:355-68. [PMID: 20808057 DOI: 10.3412/jsb.65.355] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Takashi Matsuba
- Division of Bacteriology, Department of Microbiology and Immunology, School of Medicine Tottori University, Yonago, Tottori
| | | | | |
Collapse
|
40
|
Jin Y, Xin Y, Zhang W, Ma Y. Mycobacterium tuberculosis Rv1302 and Mycobacterium smegmatis MSMEG_4947 have WecA function and MSMEG_4947 is required for the growth of M. smegmatis. FEMS Microbiol Lett 2010; 310:54-61. [PMID: 20637039 DOI: 10.1111/j.1574-6968.2010.02045.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
The disaccharide d-N-acetylglucosamine-l-rhamnose plays an important role in the mycobacterial cell wall as a linker connecting arabinogalactan and peptidoglycan via a phosphodiester linkage. The first step of the disaccharide linker is the formation of decaprenyl phosphate-GlcNAc, which is catalyzed by GlcNAc-1-phosphate transferase. In Gram-negative bacteria, the wecA gene specifies the UDP-GlcNAc: undecaprenyl phosphate GlcNAc-1-phosphate transferase (WecA), which catalyzes the first step in the biosynthesis of lipopolysaccharide O-antigen. Mycobacterium tuberculosis Rv1302 and Mycobacterium smegmatis MSMEG_4947 show homology to Escherichia coli WecA protein. We cloned Rv1302 and MSMEG_4947 and introduced plasmids pYJ-1 (carrying Rv1302) and pYJ-2 (carrying MSMEG_4947) into a wecA-defective strain of E. coli MV501, respectively. Lipopolysaccharide analysis demonstrated that lipopolysaccharide synthesis in MV501 (pYJ-1) and MV501 (pYJ-2) was restored upon complementation with Rv1302 and MSMEG_4947, respectively. This provides the first evidence that Rv1302 and MSMEG_4947 have the same function as E. coli WecA. We also generated an M. smegmatis MSMEG_4947 knockout mutant using a homologous recombination strategy. The disruption of MSMEG_4947 in the M. smegmatis genome resulted in the loss of viability at a nonpermissive temperature. Scanning electron microscopy and transmission electron microscopy results showed that the lack of the MSMEG_4947 protein causes drastic morphological changes in M. smegmatis.
Collapse
Affiliation(s)
- Yue Jin
- Department of Biochemistry and Molecular Biology, Dalian Medical University, 9 W. Lushun South Road, Dalian, China
| | | | | | | |
Collapse
|
41
|
Xie P, Zhang Q. Pathogenesis and treatment of non-alcoholic fatty liver disease. ACTA ACUST UNITED AC 2010; 8:201-9. [DOI: 10.3736/jcim20100301] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
|
42
|
Umesiri FE, Sanki AK, Boucau J, Ronning DR, Sucheck SJ. Recent advances toward the inhibition of mAG and LAM synthesis in Mycobacterium tuberculosis. Med Res Rev 2010; 30:290-326. [DOI: 10.1002/med.20190] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
43
|
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.
Collapse
Affiliation(s)
- Devinder Kaur
- Department of Microbiology, Immunology and Pathology, Mycobacteria Research Laboratories, Colorado State University, Fort Collins, CO 80523-1682, USA
| | | | | | | | | |
Collapse
|
44
|
Vissa VD, Sakamuri RM, Li W, Brennan PJ. Defining mycobacteria: Shared and specific genome features for different lifestyles. Indian J Microbiol 2009; 49:11-47. [PMID: 23100749 DOI: 10.1007/s12088-009-0006-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2007] [Accepted: 08/16/2008] [Indexed: 11/28/2022] Open
Abstract
During the last decade, the combination of rapid whole genome sequencing capabilities, application of genetic and computational tools, and establishment of model systems for the study of a range of species for a spectrum of biological questions has enhanced our cumulative knowledge of mycobacteria in terms of their growth properties and requirements. The adaption of the corynebacterial surrogate system has simplified the study of cell wall biosynthetic machinery common to actinobacteria. Comparative genomics supported by experimentation reveals that superimposed on a common core of 'mycobacterial' gene set, pathogenic mycobacteria are endowed with multiple copies of several protein families that encode novel secretion and transport systems such as mce and esx; immunomodulators named PE/PPE proteins, and polyketide synthases for synthesis of complex lipids. The precise timing of expression, engagement and interactions involving one or more of these redundant proteins in their host environments likely play a role in the definition and differentiation of species and their disease phenotypes. Besides these, only a few species specific 'virulence' factors i.e., macromolecules have been discovered. Other subtleties may also arise from modifications of shared macromolecules. In contrast, to cope with the broad and changing growth conditions, their saprophytic relatives have larger genomes, in which the excess coding capacity is dedicated to transcriptional regulators, transporters for nutrients and toxic metabolites, biosynthesis of secondary metabolites and catabolic pathways. In this review, we present a sampling of the tools and techniques that are being implemented to tease apart aspects of physiology, phylogeny, ecology and pathology and illustrate the dominant genomic characteristics of representative species. The investigation of clinical isolates, natural disease states and discovery of new diagnostics, vaccines and drugs for existing and emerging mycobacterial diseases, particularly for multidrug resistant strains are the challenges in the coming decades.
Collapse
Affiliation(s)
- Varalakshmi D Vissa
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO-80523-1628 USA
| | | | | | | |
Collapse
|
45
|
Grzegorzewicz AE, Ma Y, Jones V, Crick D, Liav A, McNeil MR. Development of a microtitre plate-based assay for lipid-linked glycosyltransferase products using the mycobacterial cell wall rhamnosyltransferase WbbL. MICROBIOLOGY-SGM 2009; 154:3724-3730. [PMID: 19047740 DOI: 10.1099/mic.0.2008/023366-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
In Mycobacterium tuberculosis a rhamnosyltransferase (WbbL) catalyses the transfer of an alpha-L-Rhap residue from dTDP-L-rhamnose (dTDP-Rha) to decaprenyldiphosphoryl-alpha-D-N-acetylglucosamine (GlcNAc-P-P-DP) to form alpha-L-Rhap-(1-->3)-alpha-D-GlcNAc-P-P-DP, which is then further elongated with Galf and Araf units, and finally mycolylated and attached to the peptidoglycan. This enzyme is essential for M. tuberculosis viability and at the same time absent in eukaryotic cells, and is therefore a good target for the development of new antituberculosis therapeutics. Here, we report a microtitre plate-based method for the assay of this enzyme using a crude membrane preparation from an Escherichia coli strain overexpressing wbbL as an enzyme source and the natural acceptor substrate GlcNAc-P-P-DP. Initial characterization of the enzyme included unequivocal identification of the product Rha-GlcNAc-P-P-DP by liquid chromatography (LC)-MS, and the facts that WbbL shows an absolute requirement for divalent cations and that its activity is stimulated by beta-mercaptoethanol. Its pH optimum and basic kinetic parameters were also determined, and the kinetic analysis showed that WbbL uses a ternary complex mechanism. The microtitre plate-based assay for this enzyme was developed by taking advantage of the lipophilic nature of the product. This assay should be readily transferable to other glycosyltransferases which use lipid-based acceptors and aid greatly in obtaining inhibitors of such glycosyltransferases for new drug development.
Collapse
Affiliation(s)
- Anna E Grzegorzewicz
- Department of Microbiology, Colorado State University, Fort Collins, CO 80523, USA
| | - Yufang Ma
- Dalian Medical University, Dalian, PR China.,Department of Microbiology, Colorado State University, Fort Collins, CO 80523, USA
| | - Victoria Jones
- Department of Microbiology, Colorado State University, Fort Collins, CO 80523, USA
| | - Dean Crick
- Department of Microbiology, Colorado State University, Fort Collins, CO 80523, USA
| | - Avraham Liav
- Department of Microbiology, Colorado State University, Fort Collins, CO 80523, USA
| | - Michael R McNeil
- Department of Microbiology, Colorado State University, Fort Collins, CO 80523, USA
| |
Collapse
|
46
|
Lucas R, Balbuena P, Errey JC, Squire MA, Gurcha SS, McNeil M, Besra GS, Davis BG. Glycomimetic Inhibitors of Mycobacterial Glycosyltransferases: Targeting the TB Cell Wall. Chembiochem 2008; 9:2197-9. [DOI: 10.1002/cbic.200800189] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
|
47
|
Abstract
In spite of effective antibiotics to treat TB (tuberculosis) since the early 1960s, we enter the new millennium with TB currently the leading cause of death from a single infectious agent, killing more than 3 million people worldwide each year. Thus an understanding of drug-resistance mechanisms, the immunobiology of cell wall components to elucidate host–pathogen interactions and the discovery of new drug targets are now required for the treatment of TB. Above the plasma membrane is a classical chemotype IV peptidoglycan to which is attached the macromolecular structure, mycolyl-arabinogalactan via a unique diglycosylphosphoryl bridge. The present review discusses the assembly of the mAGP (mycolyl-arabinogalactan–peptidoglycan) complex and the site of action of EMB (ethambutol), bringing forward a new era in TB research and focus for new drugs to combat multidrug-resistant TB.
Collapse
|
48
|
Birch HL, Alderwick LJ, Bhatt A, Rittmann D, Krumbach K, Singh A, Bai Y, Lowary TL, Eggeling L, Besra GS. Biosynthesis of mycobacterial arabinogalactan: identification of a novel alpha(1-->3) arabinofuranosyltransferase. Mol Microbiol 2008; 69:1191-206. [PMID: 18627460 PMCID: PMC2610374 DOI: 10.1111/j.1365-2958.2008.06354.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The cell wall mycolyl-arabinogalactan–peptidoglycan complex is essential in mycobacterial species, such as Mycobacterium tuberculosis and is the target of several antitubercular drugs. For instance, ethambutol targets arabinogalactan biosynthesis through inhibition of the arabinofuranosyltransferases Mt-EmbA and Mt-EmbB. A bioinformatics approach identified putative integral membrane proteins, MSMEG2785 in Mycobacterium smegmatis, Rv2673 in Mycobacterium tuberculosis and NCgl1822 in Corynebacterium glutamicum, with 10 predicted transmembrane domains and a glycosyltransferase motif (DDX), features that are common to the GT-C superfamily of glycosyltransferases. Deletion of M. smegmatis MSMEG2785 resulted in altered growth and glycosyl linkage analysis revealed the absence of AG α(1→3)-linked arabinofuranosyl (Araf) residues. Complementation of the M. smegmatis deletion mutant was fully restored to a wild-type phenotype by MSMEG2785 and Rv2673, and as a result, we have now termed this previously uncharacterized open reading frame, arabinofuranosyltransferase C (aftC). Enzyme assays using the sugar donor β-d-arabinofuranosyl-1-monophosphoryl-decaprenol (DPA) and a newly synthesized linear α(1→5)-linked Ara5 neoglycolipid acceptor together with chemical identification of products formed, clearly identified AftC as a branching α(1→3) arabinofuranosyltransferase. This newly discovered glycosyltransferase sheds further light on the complexities of Mycobacterium cell wall biosynthesis, such as in M. tuberculosis and related species and represents a potential new drug target.
Collapse
Affiliation(s)
- Helen L Birch
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
| | | | | | | | | | | | | | | | | | | |
Collapse
|
49
|
Goude R, Parish T. The genetics of cell wall biosynthesis in Mycobacterium tuberculosis. Future Microbiol 2008; 3:299-313. [DOI: 10.2217/17460913.3.3.299] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Despite an available vaccine and effective antibiotics, Mycobacterium tuberculosis is still the causative agent of almost 2 million deaths every year. The cell wall of M. tuberculosis is composed of sugars and lipids of exotic structure, many of which contribute to its pathogenicity. The majority of the enzymes responsible for building this structure are essential. However, they share very little homology with well-characterized enzymes, which makes their identification in the genome difficult. Despite this, our knowledge of the structure of the cell wall of M. tuberculosis is fairly complete and an increasing number of genes have been identified that are involved in its biosynthesis. By contrast, data concerning regulation of the expression of these genes and control of the cell wall composition are restricted. This review summarizes current information on the genetics of cell wall biosynthesis in M. tuberculosis, incorporating available data on gene organization and regulation.
Collapse
Affiliation(s)
| | - Tanya Parish
- Barts & the London, London, UK and, Infectious Disease Research Institute, Seattle, USA
| |
Collapse
|
50
|
Structure, function and biosynthesis of the Mycobacterium tuberculosis cell wall: arabinogalactan and lipoarabinomannan assembly with a view to discovering new drug targets. Biochem Soc Trans 2008; 35:1325-8. [PMID: 17956343 DOI: 10.1042/bst0351325] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In spite of effective antibiotics to treat TB (tuberculosis) since the early 1960s, we enter the new millennium with TB, currently the leading cause of death from a single infectious agent, killing more than three million people worldwide each year. Thus an understanding of drug-resistance mechanisms, the immunobiology of cell wall components to elucidate host-pathogen interactions and the discovery of new drug targets are now required for the treatment of TB. Above the plasma membrane is a classical chemotype IV PG (peptidoglycan) to which is attached the macromolecular structure, mycolyl-arabinogalactan, via a unique diglycosylphosphoryl bridge. This review will discuss the assembly of the mAGP (mycolyl-arabinogalactan-peptidoglycan), its associated glycolipids and the site of action of EMB (ethambutol), bringing forward a new era in TB research and focus on new drugs to combat multidrug resistant TB.
Collapse
|