1
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Patel RR, Arun PP, Singh SK, Singh M. Mycobacterial biofilms: Understanding the genetic factors playing significant role in pathogenesis, resistance and diagnosis. Life Sci 2024; 351:122778. [PMID: 38879157 DOI: 10.1016/j.lfs.2024.122778] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2023] [Revised: 05/25/2024] [Accepted: 06/04/2024] [Indexed: 07/03/2024]
Abstract
Even though the genus Mycobacterium is a diverse group consisting of a majority of environmental bacteria known as non-tuberculous mycobacteria (NTM), it also contains some of the deadliest pathogens (Mycobacterium tuberculosis) in history associated with chronic disease called tuberculosis (TB). Formation of biofilm is one of the unique strategies employed by mycobacteria to enhance their ability to survive in hostile conditions. Biofilm formation by Mycobacterium species is an emerging area of research with significant implications for understanding its pathogenesis and treatment of related infections, specifically TB. This review provides an overview of the biofilm-forming abilities of different species of Mycobacterium and the genetic factors influencing biofilm formation with a detailed focus on M. tuberculosis. Biofilm-mediated resistance is a significant challenge as it can limit antibiotic penetration and promote the survival of dormant mycobacterial cells. Key genetic factors promoting biofilm formation have been explored such as the mmpL genes involved in lipid transport and cell wall integrity as well as the groEL gene essential for mature biofilm formation. Additionally, biofilm-mediated antibiotic resistance and pathogenesis highlighting the specific niches, sites of infection along with the possible mechanisms of biofilm dissemination have been discussed. Furthermore, drug targets within mycobacterial biofilm and their role as potential biomarkers in the development of rapid diagnostic tools have been highlighted. The review summarises the current understanding of the complex nature of Mycobacterium biofilm and its clinical implications, paving the way for advancements in the field of disease diagnosis, management and treatment against its multi-drug resistant species.
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Affiliation(s)
- Ritu Raj Patel
- Department of Medicinal Chemistry, Faculty of Ayurveda, Institute of Medical Sciences, Banaras Hindu University, Varanasi 221005, India
| | - Pandey Priya Arun
- Department of Medicinal Chemistry, Faculty of Ayurveda, Institute of Medical Sciences, Banaras Hindu University, Varanasi 221005, India
| | - Sudhir Kumar Singh
- Department of Microbiology, Institute of Medical Sciences, Banaras Hindu University, Varanasi 221005, India
| | - Meenakshi Singh
- Department of Medicinal Chemistry, Faculty of Ayurveda, Institute of Medical Sciences, Banaras Hindu University, Varanasi 221005, India.
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2
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Brown T, Chavent M, Im W. Molecular Modeling and Simulation of the Mycobacterial Cell Envelope: From Individual Components to Cell Envelope Assemblies. J Phys Chem B 2023; 127:10941-10949. [PMID: 38091517 PMCID: PMC10758119 DOI: 10.1021/acs.jpcb.3c06136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2023] [Revised: 11/14/2023] [Accepted: 11/16/2023] [Indexed: 12/29/2023]
Abstract
Unlike typical Gram-positive bacteria, the cell envelope of mycobacteria is unique and composed of a mycobacterial outer membrane, also known as the mycomembrane, a peptidoglycan layer, and a mycobacterial inner membrane, which is analogous to that of Gram-negative bacteria. Despite its importance, however, our understanding of this complex cell envelope is rudimentary at best. Thus, molecular modeling and simulation of such an envelope can benefit the scientific community by proposing new hypotheses about the biophysical properties of its different layers. In this Perspective, we present recent advances in molecular modeling and simulation of the mycobacterial cell envelope from individual components to cell envelope assemblies. We also show how modeling other types of cell envelopes, such as that of Escherichia coli, may help modeling part of the mycobacterial envelopes. We hope that the studies presented here are just the beginning of the road and more and more new modeling and simulation studies help us to understand crucial questions related to mycobacteria such as antibiotic resistance or bacterial survival in the host.
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Affiliation(s)
- Turner Brown
- Department
of Bioengineering, Lehigh University, Bethlehem, Pennsylvania 18015, United States
| | - Matthieu Chavent
- Institut
de Pharmacologie et Biologie Structurale, CNRS, Université
de Toulouse, 205 Route de Narbonne, 31400 Toulouse, France
| | - Wonpil Im
- Department
of Bioengineering, Lehigh University, Bethlehem, Pennsylvania 18015, United States
- Departments
of Biological Sciences and Chemistry, Lehigh
University, Bethlehem, Pennsylvania 18015, United States
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3
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Liu X, Brčić J, Cassell GH, Cegelski L. CPMAS NMR platform for direct compositional analysis of mycobacterial cell-wall complexes and whole cells. JOURNAL OF MAGNETIC RESONANCE OPEN 2023; 16-17:100127. [PMID: 38125335 PMCID: PMC10732466 DOI: 10.1016/j.jmro.2023.100127] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/23/2023]
Abstract
Tuberculosis and non-tuberculosis mycobacterial infections are rising each year and often result in chronic incurable disease. Important antibiotics target cell-wall biosynthesis, yet some mycobacteria are alarmingly resistant or tolerant to currently available antibiotics. This resistance is often attributed to assumed differences in composition of the complex cell wall of different mycobacterial strains and species. However, due to the highly crosslinked and insoluble nature of mycobacterial cell walls, direct comparative determinations of cell-wall composition pose a challenge to analysis through conventional biochemical analyses. We introduce an approach to directly observe the chemical composition of mycobacterial cell walls using solid-state NMR spectroscopy. 13C CPMAS spectra are provided of individual components (peptidoglycan, arabinogalactan, and mycolic acids) and of in situ cell-wall complexes. We assigned the spectroscopic contributions of each component in the cell-wall spectrum. We uncovered a higher arabinogalactan-to-peptidoglycan ratio in the cell wall of M. abscessus, an organism noted for its antibiotic resistance, relative to M. smegmatis. Furthermore, differentiating influences of different types of cell-wall targeting antibiotics were observed in spectra of antibiotic-treated whole cells. This platform will be of value in evaluating cell-wall composition and antibiotic activity among different mycobacteria and in considering the most effective combination treatment regimens.
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Affiliation(s)
- Xinyu Liu
- Department of Chemistry, Stanford University, CA 94305, United States
| | - Jasna Brčić
- Department of Chemistry, Stanford University, CA 94305, United States
| | - Gail H. Cassell
- PAI Life Sciences Inc, Seattle WA 98102, United States
- Department of Global Health and Social Medicine, Harvard Medical School, Boston, MA 02115, United States
| | - Lynette Cegelski
- Department of Chemistry, Stanford University, CA 94305, United States
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4
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Palčeková Z, Obregón-Henao A, De K, Walz A, Lam H, Philp J, Angala SK, Patterson J, Pearce C, Zuberogoitia S, Avanzi C, Nigou J, McNeil M, Muñoz Gutiérrez JF, Gilleron M, Wheat WH, Gonzalez-Juarrero M, Jackson M. Role of succinyl substituents in the mannose-capping of lipoarabinomannan and control of inflammation in Mycobacterium tuberculosis infection. PLoS Pathog 2023; 19:e1011636. [PMID: 37669276 PMCID: PMC10503756 DOI: 10.1371/journal.ppat.1011636] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 09/15/2023] [Accepted: 08/25/2023] [Indexed: 09/07/2023] Open
Abstract
The covalent modification of bacterial (lipo)polysaccharides with discrete substituents may impact their biosynthesis, export and/or biological activity. Whether mycobacteria use a similar strategy to control the biogenesis of its cell envelope polysaccharides and modulate their interaction with the host during infection is unknown despite the report of a number of tailoring substituents modifying the structure of these glycans. Here, we show that discrete succinyl substituents strategically positioned on Mycobacterium tuberculosis (Mtb) lipoarabinomannan govern the mannose-capping of this lipoglycan and, thus, much of the biological activity of the entire molecule. We further show that the absence of succinyl substituents on the two main cell envelope glycans of Mtb, arabinogalactan and lipoarabinomannan, leads to a significant increase of pro-inflammatory cytokines and chemokines in infected murine and human macrophages. Collectively, our results validate polysaccharide succinylation as a critical mechanism by which Mtb controls inflammation.
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Affiliation(s)
- Zuzana Palčeková
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, United States of America
| | - Andrés Obregón-Henao
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, United States of America
| | - Kavita De
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, United States of America
| | - Amanda Walz
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, United States of America
| | - Ha Lam
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, United States of America
| | - Jamie Philp
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, United States of America
| | - Shiva Kumar Angala
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, United States of America
| | - Johnathan Patterson
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, United States of America
| | - Camron Pearce
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, United States of America
| | - Sophie Zuberogoitia
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Charlotte Avanzi
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, United States of America
| | - Jérôme Nigou
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Michael McNeil
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, United States of America
| | - Juan F. Muñoz Gutiérrez
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, United States of America
| | - Martine Gilleron
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - William H. Wheat
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, United States of America
| | - Mercedes Gonzalez-Juarrero
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, United States of America
| | - Mary Jackson
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado, United States of America
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5
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Gong Y, Wang J, Li F, Zhu B. Polysaccharides and glycolipids of Mycobacterium tuberculosis and their induced immune responses. Scand J Immunol 2023; 97:e13261. [PMID: 39008002 DOI: 10.1111/sji.13261] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2022] [Revised: 02/05/2023] [Accepted: 02/16/2023] [Indexed: 07/16/2024]
Abstract
Tuberculosis (TB) is a chronic infectious disease mainly caused by Mycobacterium tuberculosis (M. tuberculosis). The structures of polysaccharides and glycolipids at M. tuberculosis cell wall vary among different strains, which affect the physiology and pathogenesis of mycobacteria by activating or inhibiting innate and acquired immunity. Among them, some components such as lipomannan (LM) and lipoarabinomannan (LAM) activate innate immunity by recognizing some kinds of pattern recognition receptors (PRRs) like Toll-like receptors, while other components like mannose-capped lipoarabinomannan (ManLAM) could prevent innate immune responses by inhibiting the secretion of pro-inflammatory cytokines and maturation of phagosomes. In addition, many glycolipids can activate natural killer T (NKT) cells and CD1-restricted T cells to produce interferon-γ (IFN-γ). Furthermore, humoral immunity against cell wall components, such as antibodies against LAM, plays a role in immunity against M. tuberculosis infection. Cell wall polysaccharides and glycolipids of M. tuberculosis have potential applications as antigens and adjuvants for novel TB subunit vaccines.
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Affiliation(s)
- Yang Gong
- Gansu Provincial Key Laboratory of Evidence Based Medicine and Clinical Translation & Lanzhou Center for Tuberculosis Research, Institute of Pathogen Biology, School of Basic Medical Sciences, Lanzhou University, Lanzhou, China
| | - Juan Wang
- Gansu Provincial Key Laboratory of Evidence Based Medicine and Clinical Translation & Lanzhou Center for Tuberculosis Research, Institute of Pathogen Biology, School of Basic Medical Sciences, Lanzhou University, Lanzhou, China
| | - Fei Li
- Gansu Provincial Key Laboratory of Evidence Based Medicine and Clinical Translation & Lanzhou Center for Tuberculosis Research, Institute of Pathogen Biology, School of Basic Medical Sciences, Lanzhou University, Lanzhou, China
| | - Bingdong Zhu
- Gansu Provincial Key Laboratory of Evidence Based Medicine and Clinical Translation & Lanzhou Center for Tuberculosis Research, Institute of Pathogen Biology, School of Basic Medical Sciences, Lanzhou University, Lanzhou, China
- State Key Laboratory of Veterinary Etiological Biology, College of Veterinary Medicine, Lanzhou University, Lanzhou, China
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6
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Singh BK, Biswas R, Bhattacharyya S, Basak A, Das AK. The C‐terminal end of mycobacterial HadBC regulates AcpM interaction during the FAS‐II pathway: a structural perspective. FEBS J 2022; 289:4963-4980. [DOI: 10.1111/febs.16405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2021] [Revised: 01/22/2022] [Accepted: 02/15/2022] [Indexed: 11/26/2022]
Affiliation(s)
- Bina Kumari Singh
- School of Biosciences Indian Institute of Technology Kharagpur India
| | - Rupam Biswas
- Department of Biotechnology Indian Institute of Technology Kharagpur India
| | - Sudipta Bhattacharyya
- Department of Bioscience & Bioengineering Indian Institute of Technology Jodhpur India
| | - Amit Basak
- Department of Chemistry Indian Institute of Technology Kharagpur India
| | - Amit K. Das
- Department of Biotechnology Indian Institute of Technology Kharagpur India
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7
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Banahene N, Kavunja HW, Swarts BM. Chemical Reporters for Bacterial Glycans: Development and Applications. Chem Rev 2022; 122:3336-3413. [PMID: 34905344 PMCID: PMC8958928 DOI: 10.1021/acs.chemrev.1c00729] [Citation(s) in RCA: 50] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Bacteria possess an extraordinary repertoire of cell envelope glycans that have critical physiological functions. Pathogenic bacteria have glycans that are essential for growth and virulence but are absent from humans, making them high-priority targets for antibiotic, vaccine, and diagnostic development. The advent of metabolic labeling with bioorthogonal chemical reporters and small-molecule fluorescent reporters has enabled the investigation and targeting of specific bacterial glycans in their native environments. These tools have opened the door to imaging glycan dynamics, assaying and inhibiting glycan biosynthesis, profiling glycoproteins and glycan-binding proteins, and targeting pathogens with diagnostic and therapeutic payload. These capabilities have been wielded in diverse commensal and pathogenic Gram-positive, Gram-negative, and mycobacterial species─including within live host organisms. Here, we review the development and applications of chemical reporters for bacterial glycans, including peptidoglycan, lipopolysaccharide, glycoproteins, teichoic acids, and capsular polysaccharides, as well as mycobacterial glycans, including trehalose glycolipids and arabinan-containing glycoconjugates. We cover in detail how bacteria-targeting chemical reporters are designed, synthesized, and evaluated, how they operate from a mechanistic standpoint, and how this information informs their judicious and innovative application. We also provide a perspective on the current state and future directions of the field, underscoring the need for interdisciplinary teams to create novel tools and extend existing tools to support fundamental and translational research on bacterial glycans.
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Affiliation(s)
- Nicholas Banahene
- Department of Chemistry and Biochemistry, Central Michigan University, Mount Pleasant, MI, United States
- Biochemistry, Cell, and Molecular Biology Program, Central Michigan University, Mount Pleasant, MI, United States
| | - Herbert W. Kavunja
- Department of Chemistry and Biochemistry, Central Michigan University, Mount Pleasant, MI, United States
- Biochemistry, Cell, and Molecular Biology Program, Central Michigan University, Mount Pleasant, MI, United States
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8
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Modak B, Girkar S, Narayan R, Kapoor S. Mycobacterial Membranes as Actionable Targets for Lipid-Centric Therapy in Tuberculosis. J Med Chem 2022; 65:3046-3065. [PMID: 35133820 DOI: 10.1021/acs.jmedchem.1c01870] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Infectious diseases remain significant health concerns worldwide, and resistance is particularly common in patients with tuberculosis caused by Mycobacterium tuberculosis. The development of anti-infectives with novel modes of action may help overcome resistance. In this regard, membrane-active agents, which modulate membrane components essential for the survival of pathogens, present attractive antimicrobial agents. Key advantages of membrane-active compounds include their ability to target slow-growing or dormant bacteria and their favorable pharmacokinetics. Here, we comprehensively review recent advances in the development of membrane-active chemotypes that target mycobacterial membranes and discuss clinically relevant membrane-active antibacterial agents that have shown promise in counteracting bacterial infections. We discuss the relationship between the membrane properties and the synthetic requirements within the chemical scaffold, as well as the limitations of current membrane-active chemotypes. This review will lay the chemical groundwork for the development of membrane-active antituberculosis agents and will foster the discovery of more effective antitubercular agents.
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Affiliation(s)
- Biswabrata Modak
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Siddhali Girkar
- School of Chemical and Materials Sciences, Indian Institute of Technology Goa, Goa 403110, India
| | - Rishikesh Narayan
- School of Chemical and Materials Sciences, Indian Institute of Technology Goa, Goa 403110, India
| | - Shobhna Kapoor
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400076, India.,Graduate School of Integrated Sciences for Life, Hiroshima University, Hiroshima 739-8528, Japan
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9
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Papadopoulos AO, Ealand C, Gordhan BG, VanNieuwenhze M, Kana BD. Characterisation of a putative M23-domain containing protein in Mycobacterium tuberculosis. PLoS One 2021; 16:e0259181. [PMID: 34784363 PMCID: PMC8594824 DOI: 10.1371/journal.pone.0259181] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2020] [Accepted: 10/14/2021] [Indexed: 12/01/2022] Open
Abstract
Mycobacterium tuberculosis, the causative agent of tuberculosis remains a global health concern, further compounded by the high rates of HIV-TB co-infection and emergence of multi- and extensive drug resistant TB, all of which have hampered efforts to eradicate this disease. As a result, novel anti-tubercular interventions are urgently required, with the peptidoglycan component of the M. tuberculosis cell wall emerging as an attractive drug target. Peptidoglycan M23 endopeptidases can function as active cell wall hydrolases or degenerate activators of hydrolases in a variety of bacteria, contributing to important processes such as bacterial growth, division and virulence. Herein, we investigate the function of the Rv0950-encoded putative M23 endopeptidase in M. tuberculosis. In silico analysis revealed that this protein is conserved in mycobacteria, with a zinc-binding catalytic site predictive of hydrolytic activity. Transcript analysis indicated that expression of Rv0950c was elevated during lag and log phases of growth and reduced in stationary phase. Deletion of Rv0950c yielded no defects in growth, colony morphology, antibiotic susceptibility or intracellular survival but caused a reduction in cell length. Staining with a monopeptide-derived fluorescent D-amino acid, which spatially reports on sites of active PG biosynthesis or repair, revealed an overall reduction in uptake of the probe in ΔRv0950c. When stained with a dipeptide probe in the presence of cell wall damaging agents, the ΔRv0950c mutant displayed reduced sidewall labelling. As bacterial peptidoglycan metabolism is important for survival and pathogenesis, the role of Rv0950c and other putative M23 endopeptidases in M. tuberculosis should be explored further.
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Affiliation(s)
- Andrea Olga Papadopoulos
- Faculty of Health Sciences, DSI/NRF Centre of Excellence for Biomedical TB Research, School of Pathology, University of the Witwatersrand, National Health Laboratory Service, Johannesburg, South Africa
| | - Christopher Ealand
- Faculty of Health Sciences, DSI/NRF Centre of Excellence for Biomedical TB Research, School of Pathology, University of the Witwatersrand, National Health Laboratory Service, Johannesburg, South Africa
| | - Bhavna Gowan Gordhan
- Faculty of Health Sciences, DSI/NRF Centre of Excellence for Biomedical TB Research, School of Pathology, University of the Witwatersrand, National Health Laboratory Service, Johannesburg, South Africa
| | - Michael VanNieuwenhze
- Department of Chemistry, Indiana University Bloomington, Bloomington, Indiana, United States of America
| | - Bavesh Davandra Kana
- Faculty of Health Sciences, DSI/NRF Centre of Excellence for Biomedical TB Research, School of Pathology, University of the Witwatersrand, National Health Laboratory Service, Johannesburg, South Africa
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10
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Gerbst AG, Krylov VB, Nifantiev NE. Computational and NMR Conformational Analysis of Galactofuranoside Cycles Presented in Bacterial and Fungal Polysaccharide Antigens. Front Mol Biosci 2021; 8:719396. [PMID: 34513924 PMCID: PMC8424007 DOI: 10.3389/fmolb.2021.719396] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Accepted: 07/27/2021] [Indexed: 11/24/2022] Open
Abstract
Unlike pyranoside cycles which are generally characterized by strictly defined conformational preferences, furanosides are flexible and may adopt a wide range of available conformations. During our previous studies, conformational changes of galactofuranoside cycles upon total sulfation were described computationally, using a simple Hartree–Fock (HF) method, and principal conformers of the 5-membered galactose ring were revealed. However, in the case of more complex disaccharide structures, it was found that this method and the widely applied DFT-B3LYP produced results that deviated from experimental evidence. In this study, other DFT functionals (PBE0 and double hybrid B2PLYP) along with RI-MP2 are employed to study the conformational behavior of the galactofuranoside ring. Reinvestigation of galactofuranosides with a lactic acid substituent at O-3 revealed that changes in the orientation of lactic acid residue at O-3 might induce conformational changes of the furanoside cycle. Such findings are important for further modeling of carbohydrate–protein interaction.
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Affiliation(s)
- Alexey G Gerbst
- Laboratory of Glycoconjugate Chemistry, N.D. Zelinsky Institute of Organic Chemistry RAS, Moscow, Russia
| | - Vadim B Krylov
- Laboratory of Glycoconjugate Chemistry, N.D. Zelinsky Institute of Organic Chemistry RAS, Moscow, Russia
| | - Nikolay E Nifantiev
- Laboratory of Glycoconjugate Chemistry, N.D. Zelinsky Institute of Organic Chemistry RAS, Moscow, Russia
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11
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Jackson M, Stevens CM, Zhang L, Zgurskaya HI, Niederweis M. Transporters Involved in the Biogenesis and Functionalization of the Mycobacterial Cell Envelope. Chem Rev 2021; 121:5124-5157. [PMID: 33170669 PMCID: PMC8107195 DOI: 10.1021/acs.chemrev.0c00869] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The biology of mycobacteria is dominated by a complex cell envelope of unique composition and structure and of exceptionally low permeability. This cell envelope is the basis of many of the pathogenic features of mycobacteria and the site of susceptibility and resistance to many antibiotics and host defense mechanisms. This review is focused on the transporters that assemble and functionalize this complex structure. It highlights both the progress and the limits of our understanding of how (lipo)polysaccharides, (glyco)lipids, and other bacterial secretion products are translocated across the different layers of the cell envelope to their final extra-cytoplasmic location. It further describes some of the unique strategies evolved by mycobacteria to import nutrients and other products through this highly impermeable barrier.
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Affiliation(s)
- Mary Jackson
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523-1682, USA
| | - Casey M. Stevens
- University of Oklahoma, Department of Chemistry and Biochemistry, 101 Stephenson Parkway, Norman, OK 73019, USA
| | - Lei Zhang
- Department of Microbiology, University of Alabama at Birmingham, 845 19th Street South, Birmingham, AL 35294, USA
| | - Helen I. Zgurskaya
- University of Oklahoma, Department of Chemistry and Biochemistry, 101 Stephenson Parkway, Norman, OK 73019, USA
| | - Michael Niederweis
- Department of Microbiology, University of Alabama at Birmingham, 845 19th Street South, Birmingham, AL 35294, USA
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12
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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: 5] [Impact Index Per Article: 1.3] [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.
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13
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Abstract
The mycomembrane layer of the mycobacterial cell envelope is a barrier to environmental, immune, and antibiotic insults. There is considerable evidence of mycomembrane plasticity during infection and in response to host-mimicking stresses. The mycomembrane layer of the mycobacterial cell envelope is a barrier to environmental, immune, and antibiotic insults. There is considerable evidence of mycomembrane plasticity during infection and in response to host-mimicking stresses. Since mycobacteria are resource and energy limited under these conditions, it is likely that remodeling has distinct requirements from those of the well-characterized biosynthetic program that operates during unrestricted growth. Unexpectedly, we found that mycomembrane remodeling in nutrient-starved, nonreplicating mycobacteria includes synthesis in addition to turnover. Mycomembrane synthesis under these conditions occurs along the cell periphery, in contrast to the polar assembly of actively growing cells, and both liberates and relies on the nonmammalian disaccharide trehalose. In the absence of trehalose recycling, de novo trehalose synthesis fuels mycomembrane remodeling. However, mycobacteria experience ATP depletion, enhanced respiration, and redox stress, hallmarks of futile cycling and the collateral dysfunction elicited by some bactericidal antibiotics. Inefficient energy metabolism compromises the survival of trehalose recycling mutants in macrophages. Our data suggest that trehalose recycling alleviates the energetic burden of mycomembrane remodeling under stress. Cell envelope recycling pathways are emerging targets for sensitizing resource-limited bacterial pathogens to host and antibiotic pressure.
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14
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Angala SK, Joe M, McNeil MR, Liav A, Lowary TL, Jackson M. Use of Synthetic Glycolipids to Probe the Number and Position of Arabinan Chains on Mycobacterial Arabinogalactan. ACS Chem Biol 2021; 16:20-26. [PMID: 33382235 PMCID: PMC7859836 DOI: 10.1021/acschembio.0c00765] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The arabinogalactan of Corynebacterianeae is a critical heteropolysaccharide that tethers outer membrane mycolic acids to peptidoglycan thus forming the characteristic cell wall core of these prokaryotes. An essential α-(1→5)-arabinosyltransferase, AftA, is responsible for the transfer of the first arabinofuranosyl (Araf) unit of the arabinan domain to the galactan backbone of arabinogalactan, but the number and precise position at which Araf residue(s) is/are added in mycobacteria remain ill-defined. Using membrane preparations from Mycobacterium smegmatis overexpressing aftA, farnesyl-phospho-arabinose as an Araf donor, and a series of synthetic galactan acceptors of various lengths, we here show that a single priming arabinosyl residue substitutes the C-5 position of a precisely positioned internal 6-linked galactofuranosyl residue of the galactan acceptors, irrespective of their length. This unexpected result suggests that, like the structurally related mycobacterial lipoarabinomannans, the arabinogalactan of mycobacteria may in fact harbor a single arabinan chain.
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Affiliation(s)
- Shiva Kumar Angala
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523-1682, USA
| | - Maju Joe
- Department of Chemistry, The University of Alberta, Edmonton, AB, T6G 2G2, Canada
| | - Michael R. McNeil
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523-1682, USA
| | - Avraham Liav
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523-1682, USA
| | - Todd L. Lowary
- Department of Chemistry, The University of Alberta, Edmonton, AB, T6G 2G2, Canada
- Institute of Biological Chemistry, Academia Sinica, Nangang Taipei 11529, Taiwan
| | - Mary Jackson
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523-1682, USA
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15
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Kumar G, Narayan R, Kapoor S. Chemical Tools for Illumination of Tuberculosis Biology, Virulence Mechanisms, and Diagnosis. J Med Chem 2020; 63:15308-15332. [PMID: 33307693 DOI: 10.1021/acs.jmedchem.0c01337] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Tuberculosis (TB) remains one of the deadliest infectious diseases and begs the scientific community to up the ante for research and exploration of completely novel therapeutic avenues. Chemical biology-inspired design of tunable chemical tools has aided in clinical diagnosis, facilitated discovery of therapeutics, and begun to enable investigation of virulence mechanisms at the host-pathogen interface of Mycobacterium tuberculosis. This Perspective highlights chemical tools specific to mycobacterial proteins and the cell lipid envelope that have furnished rapid and selective diagnostic strategies and provided unprecedented insights into the function of the mycobacterial proteome and lipidome. We discuss chemical tools that have enabled elucidating otherwise intractable biological processes by leveraging the unique lipid and metabolite repertoire of mycobacterial species. Some of these probes represent exciting starting points with the potential to illuminate poorly understood aspects of mycobacterial pathogenesis, particularly the host membrane-pathogen interactions.
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Affiliation(s)
- Gautam Kumar
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400 076, Maharashtra, India
| | - Rishikesh Narayan
- School of Chemical and Materials Sciences, Indian Institute of Technology Goa, Ponda 403 401, Goa, India
| | - Shobhna Kapoor
- Department of Chemistry, Indian Institute of Technology Bombay, Mumbai 400 076, Maharashtra, India.,Wadhwani Research Center for Bioengineering, Indian Institute of Technology Bombay, Mumbai 400 076, Maharashtra, India
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16
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Baráth M, Jakubčinová J, Konyariková Z, Kozmon S, Mikušová K, Bella M. Synthesis, docking study and biological evaluation of ᴅ-fructofuranosyl and ᴅ-tagatofuranosyl sulfones as potential inhibitors of the mycobacterial galactan synthesis targeting the galactofuranosyltransferase GlfT2. Beilstein J Org Chem 2020; 16:1853-1862. [PMID: 32802202 PMCID: PMC7404141 DOI: 10.3762/bjoc.16.152] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 07/09/2020] [Indexed: 12/02/2022] Open
Abstract
A series of ten novel ᴅ-fructofuranosyl and ᴅ-tagatofuranosyl sulfones bearing a 1-O-phosphono moiety and three different substituents at C-2 has been prepared. Due to the structural similarities of these scaffolds to the native substrate of mycobacterial galactofuranosyltransferase GlfT2 in the transition state, we evaluated these compounds by computational methods, as well as in an enzyme assay for the possible inhibition of the mycobacterial galactan biosynthesis. Our data show that despite favorable docking scores to the active site of GlfT2, none of these compounds serve as efficient inhibitors of the enzymes involved in the mycobacterial galactan biosynthesis.
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Affiliation(s)
- Marek Baráth
- Institute of Chemistry Slovak Academy of Sciences, Dúbravská cesta 9, SK-845 38 Bratislava, Slovakia
| | - Jana Jakubčinová
- Institute of Chemistry Slovak Academy of Sciences, Dúbravská cesta 9, SK-845 38 Bratislava, Slovakia
| | - Zuzana Konyariková
- Department of Biochemistry, Faculty of Natural Sciences, Comenius University in Bratislava, Ilkovičova 6, SK-842 15 Bratislava, Slovakia
| | - Stanislav Kozmon
- Institute of Chemistry Slovak Academy of Sciences, Dúbravská cesta 9, SK-845 38 Bratislava, Slovakia
| | - Katarína Mikušová
- Department of Biochemistry, Faculty of Natural Sciences, Comenius University in Bratislava, Ilkovičova 6, SK-842 15 Bratislava, Slovakia
| | - Maroš Bella
- Institute of Chemistry Slovak Academy of Sciences, Dúbravská cesta 9, SK-845 38 Bratislava, Slovakia
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17
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Borah K, Kearney JL, Banerjee R, Vats P, Wu H, Dahale S, Manjari Kasibhatla S, Joshi R, Bonde B, Ojo O, Lahiri R, Williams DL, McFadden J. GSMN-ML- a genome scale metabolic network reconstruction of the obligate human pathogen Mycobacterium leprae. PLoS Negl Trop Dis 2020; 14:e0007871. [PMID: 32628669 PMCID: PMC7365477 DOI: 10.1371/journal.pntd.0007871] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Revised: 07/16/2020] [Accepted: 06/02/2020] [Indexed: 11/19/2022] Open
Abstract
Leprosy, caused by Mycobacterium leprae, has plagued humanity for thousands of years and continues to cause morbidity, disability and stigmatization in two to three million people today. Although effective treatment is available, the disease incidence has remained approximately constant for decades so new approaches, such as vaccine or new drugs, are urgently needed for control. Research is however hampered by the pathogen's obligate intracellular lifestyle and the fact that it has never been grown in vitro. Consequently, despite the availability of its complete genome sequence, fundamental questions regarding the biology of the pathogen, such as its metabolism, remain largely unexplored. In order to explore the metabolism of the leprosy bacillus with a long-term aim of developing a medium to grow the pathogen in vitro, we reconstructed an in silico genome scale metabolic model of the bacillus, GSMN-ML. The model was used to explore the growth and biomass production capabilities of the pathogen with a range of nutrient sources, such as amino acids, glucose, glycerol and metabolic intermediates. We also used the model to analyze RNA-seq data from M. leprae grown in mouse foot pads, and performed Differential Producibility Analysis to identify metabolic pathways that appear to be active during intracellular growth of the pathogen, which included pathways for central carbon metabolism, co-factor, lipids, amino acids, nucleotides and cell wall synthesis. The GSMN-ML model is thereby a useful in silico tool that can be used to explore the metabolism of the leprosy bacillus, analyze functional genomic experimental data, generate predictions of nutrients required for growth of the bacillus in vitro and identify novel drug targets.
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Affiliation(s)
- Khushboo Borah
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
| | - Jacque-Lucca Kearney
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
| | - Ruma Banerjee
- HPC-Medical and Bioinformatics Applications Group, Centre for Development of Advanced Computing, C-DAC Innovation Park, Panchavati, Pashan, India
| | - Pankaj Vats
- HPC-Medical and Bioinformatics Applications Group, Centre for Development of Advanced Computing, C-DAC Innovation Park, Panchavati, Pashan, India
| | - Huihai Wu
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
| | - Sonal Dahale
- HPC-Medical and Bioinformatics Applications Group, Centre for Development of Advanced Computing, C-DAC Innovation Park, Panchavati, Pashan, India
| | - Sunitha Manjari Kasibhatla
- HPC-Medical and Bioinformatics Applications Group, Centre for Development of Advanced Computing, C-DAC Innovation Park, Panchavati, Pashan, India
| | - Rajendra Joshi
- HPC-Medical and Bioinformatics Applications Group, Centre for Development of Advanced Computing, C-DAC Innovation Park, Panchavati, Pashan, India
| | - Bhushan Bonde
- Head of Innovation Development, IT-Early Solutions, UCB Pharma, Slough, United Kingdom
| | - Olabisi Ojo
- United States Department of Health and Human Services, Health Resources and Services Administration, Healthcare Systems Bureau, National Hansen’s Disease Program, Baton Rouge, Louisiana, United States of America
| | - Ramanuj Lahiri
- United States Department of Health and Human Services, Health Resources and Services Administration, Healthcare Systems Bureau, National Hansen’s Disease Program, Baton Rouge, Louisiana, United States of America
| | - Diana L. Williams
- United States Department of Health and Human Services, Health Resources and Services Administration, Healthcare Systems Bureau, National Hansen’s Disease Program, Baton Rouge, Louisiana, United States of America
| | - Johnjoe McFadden
- Faculty of Health and Medical Sciences, University of Surrey, Guildford, United Kingdom
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18
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Nahar A, Baker AL, Nichols DS, Bowman JP, Britz ML. Application of Thin-Layer Chromatography-Flame Ionization Detection (TLC-FID) to Total Lipid Quantitation in Mycolic-Acid Synthesizing Rhodococcus and Williamsia Species. Int J Mol Sci 2020; 21:ijms21051670. [PMID: 32121355 PMCID: PMC7084869 DOI: 10.3390/ijms21051670] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Revised: 02/15/2020] [Accepted: 02/25/2020] [Indexed: 12/25/2022] Open
Abstract
In addition to cell membrane phospholipids, Actinobacteria in the order Corynebacteriales possess a waxy cell envelope containing mycolic acids (MA). In optimized culture condition, some species can also accumulate high concentrations of intracellular triacylglycerols (TAG), which are a potential source of biodiesel. Bacterial lipid classes and composition alter in response to environmental stresses, including nutrient availability, thus understanding carbon flow into different lipid classes is important when optimizing TAG synthesis. Quantitative and qualitative analysis of lipid classes normally requires combinations of different extraction, derivatization, chromatographic and detection methods. In this study, a single-step thin-layer chromatography-flame ionization detection (TLC-FID) technique was applied to quantify lipid classes in six sub-Antarctic Corynebacteriales strains identified as Rhodococcus and Williamsia species. A hexane:diethyl-ether:acetic acid solvent system separated the total cellular lipids extracted from cells lysed by bead beating, which released more bound and unbound MA than sonication. Typical profiles included a major broad non-polar lipid peak, TAG and phospholipids, although trehalose dimycolates, when present, co-eluted with phospholipids. Ultra-performance liquid chromatography-tandem mass-spectrometry and nuclear magnetic resonance spectroscopy detected MA signatures in the non-polar lipid peak and indicated that these lipids were likely bound, at least in part, to sugars from cell wall arabinogalactan. Waxy esters were not detected. The single-solvent TLC-FID procedure provides a useful platform for the quantitation and preliminary screening of cellular lipid classes when testing the impacts of growth conditions on TAG synthesis.
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Affiliation(s)
- Akhikun Nahar
- Tasmanian Institute of Agriculture, University of Tasmania, Hobart, TAS 7005, Australia; (A.N.); (A.L.B.); (J.P.B.)
| | - Anthony L. Baker
- Tasmanian Institute of Agriculture, University of Tasmania, Hobart, TAS 7005, Australia; (A.N.); (A.L.B.); (J.P.B.)
| | - David S. Nichols
- Central Science Laboratory, Division of Research, University of Tasmania, Hobart, TAS 7005, Australia;
| | - John P. Bowman
- Tasmanian Institute of Agriculture, University of Tasmania, Hobart, TAS 7005, Australia; (A.N.); (A.L.B.); (J.P.B.)
| | - Margaret L. Britz
- Tasmanian Institute of Agriculture, University of Tasmania, Hobart, TAS 7005, Australia; (A.N.); (A.L.B.); (J.P.B.)
- Correspondence:
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19
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Shen L, Viljoen A, Villaume S, Joe M, Halloum I, Chêne L, Méry A, Fabre E, Takegawa K, Lowary TL, Vincent SP, Kremer L, Guérardel Y, Mariller C. The endogenous galactofuranosidase GlfH1 hydrolyzes mycobacterial arabinogalactan. J Biol Chem 2020; 295:5110-5123. [PMID: 32107309 DOI: 10.1074/jbc.ra119.011817] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2019] [Revised: 02/11/2020] [Indexed: 12/14/2022] Open
Abstract
Despite impressive progress made over the past 20 years in our understanding of mycolylarabinogalactan-peptidoglycan (mAGP) biogenesis, the mechanisms by which the tubercle bacillus Mycobacterium tuberculosis adapts its cell wall structure and composition to various environmental conditions, especially during infection, remain poorly understood. Being the central portion of the mAGP complex, arabinogalactan (AG) is believed to be the constituent of the mycobacterial cell envelope that undergoes the least structural changes, but no reports exist supporting this assumption. Herein, using recombinantly expressed mycobacterial protein, bioinformatics analyses, and kinetic and biochemical assays, we demonstrate that the AG can be remodeled by a mycobacterial endogenous enzyme. In particular, we found that the mycobacterial GlfH1 (Rv3096) protein exhibits exo-β-d-galactofuranose hydrolase activity and is capable of hydrolyzing the galactan chain of AG by recurrent cleavage of the terminal β-(1,5) and β-(1,6)-Galf linkages. The characterization of this galactosidase represents a first step toward understanding the remodeling of mycobacterial AG.
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Affiliation(s)
- Lin Shen
- Univ. Lille, CNRS, UMR8576 - UGSF - Unit[c33c]zpi;● de Glycobiologie Structurale et Fonctionnelle, F-59000 Lille, France
| | - Albertus Viljoen
- Institut de Recherche en Infectiologie de Montpellier (IRIM), UMR9004 - CNRS/UM, 1919 route de Mende, 34293 Montpellier cedex 5, France
| | - Sydney Villaume
- Laboratoire de Chimie Bio-Organic (CBO), Université de Namur, rue de Bruxelles 61, 5000 Namur, Belgium
| | - Maju Joe
- Alberta Glycomics Centre and Department of Chemistry, University of Alberta, Edmonton AB T6G 2G2, Canada
| | - Iman Halloum
- Institut de Recherche en Infectiologie de Montpellier (IRIM), UMR9004 - CNRS/UM, 1919 route de Mende, 34293 Montpellier cedex 5, France
| | - Loïc Chêne
- Laboratoire de Chimie Bio-Organic (CBO), Université de Namur, rue de Bruxelles 61, 5000 Namur, Belgium
| | - Alexandre Méry
- Univ. Lille, CNRS, UMR8576 - UGSF - Unit[c33c]zpi;● de Glycobiologie Structurale et Fonctionnelle, F-59000 Lille, France
| | - Emeline Fabre
- Univ. Lille, CNRS, UMR8576 - UGSF - Unit[c33c]zpi;● de Glycobiologie Structurale et Fonctionnelle, F-59000 Lille, France
| | - Kaoru Takegawa
- Department of Bioscience and Biotechnology, Faculty of Agriculture, Kyushu University, 744 Motooka, Nishi-ku, Fukuoka, 819-0395, Japan
| | - Todd L Lowary
- Alberta Glycomics Centre and Department of Chemistry, University of Alberta, Edmonton AB T6G 2G2, Canada
| | - Stéphane P Vincent
- Laboratoire de Chimie Bio-Organic (CBO), Université de Namur, rue de Bruxelles 61, 5000 Namur, Belgium
| | - Laurent Kremer
- Institut de Recherche en Infectiologie de Montpellier (IRIM), UMR9004 - CNRS/UM, 1919 route de Mende, 34293 Montpellier cedex 5, France.,INSERM, Institut de Recherche en Infectiologie de Montpellier, 34293 Montpellier, France
| | - Yann Guérardel
- Univ. Lille, CNRS, UMR8576 - UGSF - Unit[c33c]zpi;● de Glycobiologie Structurale et Fonctionnelle, F-59000 Lille, France
| | - Christophe Mariller
- Univ. Lille, CNRS, UMR8576 - UGSF - Unit[c33c]zpi;● de Glycobiologie Structurale et Fonctionnelle, F-59000 Lille, France
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20
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Biosynthesis of Galactan in Mycobacterium tuberculosis as a Viable TB Drug Target? Antibiotics (Basel) 2020; 9:antibiotics9010020. [PMID: 31935842 PMCID: PMC7168186 DOI: 10.3390/antibiotics9010020] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 12/27/2019] [Accepted: 01/02/2020] [Indexed: 12/21/2022] Open
Abstract
While target-based drug design has proved successful in several therapeutic areas, this approach has not yet provided compelling outcomes in the field of antibacterial agents. This statement remains especially true for the development of novel therapeutic interventions against tuberculosis, an infectious disease that is among the top ten leading causes of death globally. Mycobacterial galactan is an important component of the protective cell wall core of the tuberculosis pathogen and it could provide a promising target for the design of new drugs. In this review, we summarize the current knowledge on galactan biosynthesis in Mycobacterium tuberculosis, including landmark findings that led to the discovery and understanding of three key enzymes in this pathway: UDP-galactose mutase, and galactofuranosyl transferases GlfT1 and GlfT2. Moreover, we recapitulate the efforts aimed at their inhibition. The predicted common transition states of the three enzymes provide the lucrative possibility of multitargeting in pharmaceutical development, a favourable property in the mitigation of drug resistance. We believe that a tight interplay between target-based computational approaches and experimental methods will result in the development of original inhibitors that could serve as the basis of a new generation of drugs against tuberculosis.
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21
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Rastogi R, Kaur G, Maan P, Bhatnagar A, Narang T, Dogra S, Kaur J. Molecular characterization and immunogenic function of ML1899 (LipG) of Mycobacterium leprae. J Med Microbiol 2019; 68:1629-1640. [PMID: 31553301 DOI: 10.1099/jmm.0.001080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Introduction. ML1899 is conserved in all mycobacterium sp. and is a middle member of mle-ML1898 operon involved in mycolic acid modification.Aim. In the present study attempts were made to characterize ML1899 in detail.Methodology. Bioinformatics tools were used for prediction of active-site residues, antigenic epitopes and a three-dimensional model of protein. The gene was cloned, expressed and purified as His-tagged protein in Escherichia coli for biophysical/biochemical characterization. Recombinant protein was used to treat THP-1 cells to study change in production of nitric oxide (NO), reactive oxygen species (ROS), cytokines and chemokines using flowcytometry/ELISA.Results. In silico analysis predicted ML1899 as a member of α/β hydrolase family with GXSXG-motif and Ser126, His282, Asp254 as active-site residues that were confirmed by site-directed mutagensis. ML1899 exhibited esterase activity. It hydrolysed pNP-butyrate as optimum substrate at pH 8.0 and 50 °C with 5.56 µM-1 min-1 catalytic efficiency. The enzyme exhibited stability up to 60 °C temperature and between pH 6.0 to 9.0. K m, V max and specific activity of ML1899 were calculated to be 400 µM, 40 µmoles min-1 ml-1 and 27 U mg- 1, respectively. ML1899 also exhibited phospholipase activity. The protein affected the survival of macrophages when treated at higher concentration. ML1899 enhanced ROS/NO production and up-regulated pro-inflammatory cytokines and chemokine including TNF-α, IFN-γ, IL-6 and IL-8 in macrophages. ML1899 was also observed to elicit humoral response in 69 % of leprosy patients.Conclusion. These results suggested that ML1899, an esterase could up-regulate the immune responses in favour of macrophages at a low concentration but kills the THP-1 macrophages cells at a higher concentration.
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Affiliation(s)
- Ruchi Rastogi
- Department of Biochemistry, BMS Block 2, South Campus, Panjab University, Sector 25, Chandigarh 160014, India
| | - Gurkamaljit Kaur
- Department of Biotechnology, BMS Block 1, South Campus, Panjab University, Sector 25, Chandigarh 160014, India
| | - Pratibha Maan
- Present address: Department of Experimental Medicine and Biotechnology, PGIMER, Chandigarh, 160012, India.,Department of Biotechnology, BMS Block 1, South Campus, Panjab University, Sector 25, Chandigarh 160014, India
| | - Archana Bhatnagar
- Department of Biochemistry, BMS Block 2, South Campus, Panjab University, Sector 25, Chandigarh 160014, India
| | - Tarun Narang
- Department of Dermatology, Veberology and Leprology, PGIMER, Chandigarh, 160012, India
| | - Sunil Dogra
- Department of Dermatology, Veberology and Leprology, PGIMER, Chandigarh, 160012, India
| | - Jagdeep Kaur
- Department of Biotechnology, BMS Block 1, South Campus, Panjab University, Sector 25, Chandigarh 160014, India
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22
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Daffé M, Marrakchi H. Unraveling the Structure of the Mycobacterial Envelope. Microbiol Spectr 2019; 7:10.1128/microbiolspec.gpp3-0027-2018. [PMID: 31267927 PMCID: PMC10957186 DOI: 10.1128/microbiolspec.gpp3-0027-2018] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Indexed: 12/28/2022] Open
Abstract
The mycobacterial cell envelope consists of a typical plasma membrane of lipid and protein surrounded by a complex cell wall composed of carbohydrate and lipid. In pathogenic species, such as Mycobacterium tuberculosis, an outermost "capsule" layer surrounds the cell wall. This wall embraces a fundamental, covalently linked "cell-wall skeleton" composed of peptidoglycan, solidly attached to arabinogalactan, whose penta-saccharide termini are esterified by very-long-chain fatty acids (mycolic acids). These fatty acids form the inner leaflet of an outer membrane, called the mycomembrane, whose outer leaflet consists of a great variety of non-covalently linked lipids and glycolipids. The thickness of the mycomembrane, which is similar to that of the plasma membrane, is surprising in view of the length of mycoloyl residues, suggesting dedicated conformations of these fatty acids. Finally, a periplasmic space also exists in mycobacteria, between the plasma membrane and the peptidoglycan. This article provides a comprehensive overview of this biologically important and structurally unique mycobacterial cell compartment.
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Affiliation(s)
- Mamadou Daffé
- Institut de Pharmacologie et de Biologie Structurale, Université de Toulouse, CNRS, UPS, Department of Tuberculosis and Infection Biology, Toulouse, France
| | - Hedia Marrakchi
- Institut de Pharmacologie et de Biologie Structurale, Université de Toulouse, CNRS, UPS, Department of Tuberculosis and Infection Biology, Toulouse, France
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23
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Han L, Wang L, Guo Z. An extensive review of studies on mycobacterium cell wall polysaccharide-related oligosaccharides – part II: Synthetic studies on complex arabinofuranosyl oligosaccharides carrying other functional motifs and related derivatives and analogs. J Carbohydr Chem 2019. [DOI: 10.1080/07328303.2019.1630840] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Liwen Han
- Biology Institute, Qilu University of Technology (Shandong Academy of Sciences), Ji′nan, China
| | - Lizhen Wang
- Biology Institute, Qilu University of Technology (Shandong Academy of Sciences), Ji′nan, China
| | - Zhongwu Guo
- Department of Chemistry, University of Florida, Gainesville, FL, United States
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24
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Menon RR, Kumari S, Kumar P, Verma A, Krishnamurthi S, Rameshkumar N. Sphingomonas pokkalii sp. nov., a novel plant associated rhizobacterium isolated from a saline tolerant pokkali rice and its draft genome analysis. Syst Appl Microbiol 2019; 42:334-342. [PMID: 30808585 DOI: 10.1016/j.syapm.2019.02.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Revised: 01/29/2019] [Accepted: 02/08/2019] [Indexed: 02/03/2023]
Abstract
Three strains L3B27T, 3CNBAF, L1A4 isolated from a brackish cultivated pokkali rice rhizosphere were characterised using a polyphasic taxonomic approach. Phylogenetic analysis based on 16S rRNA and recA gene sequences revealed that these strains were highly similar among each other and formed a separate monophyletic cluster within the genus Sphingomonas with Sphingomonas pituitosa DSM 13101T, Sphingomonas azotifigens DSM 18530T and Sphingomonas trueperi DSM 7225T as their closest relatives sharing 97.9-98.3% 16S rRNA similarity and 91.3-94.0% recA similarity values, respectively. The average nucleotide identity (ANI), average amino acid identity (AAI) and digital DNA-DNA hybridisation (dDDH) values between L3B27T (representative of the novel strains) and its phylogenetically closest Sphingomonas species were well below the established cut-off <94% (ANI/AAI) and <70% (dDDH) for species delineation. Further, the novel strains can be distinguished from its closest relatives based on several phenotypic traits. Thus, based on the polyphasic approach, we describe a novel Sphingomonas species for which the name Sphingomonas pokkalii sp. nov (type strain L3B27T=KCTC 42098T=MCC 3001T) is proposed. In addition, the novel strains were characterised for their plant associated properties and found to possess several phenotypic traits which probably explain its plant associated lifestyle. This was further confirmed by the presence of several plant associated gene features in the genome of L3B27T. Also, we could identify gene features which may likely involve in brackish water adaptation. Thus, this study provides first insights into the plant associated lifestyle, genome and taxonomy of a novel brackish adapted plant associated Sphingomonas.
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25
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Abstract
Actinobacteria is a group of diverse bacteria. Most species in this class of bacteria are filamentous aerobes found in soil, including the genus Streptomyces perhaps best known for their fascinating capabilities of producing antibiotics. These bacteria typically have a Gram-positive cell envelope, comprised of a plasma membrane and a thick peptidoglycan layer. However, there is a notable exception of the Corynebacteriales order, which has evolved a unique type of outer membrane likely as a consequence of convergent evolution. In this chapter, we will focus on the unique cell envelope of this order. This cell envelope features the peptidoglycan layer that is covalently modified by an additional layer of arabinogalactan . Furthermore, the arabinogalactan layer provides the platform for the covalent attachment of mycolic acids , some of the longest natural fatty acids that can contain ~100 carbon atoms per molecule. Mycolic acids are thought to be the main component of the outer membrane, which is composed of many additional lipids including trehalose dimycolate, also known as the cord factor. Importantly, a subset of bacteria in the Corynebacteriales order are pathogens of human and domestic animals, including Mycobacterium tuberculosis. The surface coat of these pathogens are the first point of contact with the host immune system, and we now know a number of host receptors specific to molecular patterns exposed on the pathogen's surface, highlighting the importance of understanding how the cell envelope of Actinobacteria is structured and constructed. This chapter describes the main structural and biosynthetic features of major components found in the actinobacterial cell envelopes and highlights the key differences between them.
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Affiliation(s)
- Kathryn C Rahlwes
- Department of Microbiology, University of Massachusetts, 639 North Pleasant Street, Amherst, MA, 01003, USA
| | - Ian L Sparks
- Department of Microbiology, University of Massachusetts, 639 North Pleasant Street, Amherst, MA, 01003, USA
| | - Yasu S Morita
- Department of Microbiology, University of Massachusetts, 639 North Pleasant Street, Amherst, MA, 01003, USA.
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Tanner L, Denti P, Wiesner L, Warner DF. Drug permeation and metabolism in Mycobacterium tuberculosis: Prioritising local exposure as essential criterion in new TB drug development. IUBMB Life 2018; 70:926-937. [PMID: 29934964 PMCID: PMC6129860 DOI: 10.1002/iub.1866] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2018] [Revised: 04/11/2018] [Accepted: 04/11/2018] [Indexed: 12/22/2022]
Abstract
Anti-tuberculosis (TB) drugs possess diverse abilities to penetrate the different host tissues and cell types in which infecting Mycobacterium tuberculosis bacilli are located during active disease. This is important since there is increasing evidence that the respective "lesion-penetrating" properties of the front-line TB drugs appear to correlate well with their specific activity in standard combination therapy. In turn, these observations suggest that rational efforts to discover novel treatment-shortening drugs and drug combinations should incorporate knowledge about the comparative abilities of both existing and experimental anti-TB agents to access bacilli in defined physiological states at different sites of infection, as well as avoid elimination by efflux or inactivation by host or bacterial metabolism. However, while there is a fundamental requirement to understand the mode of action and pharmacological properties of any current or experimental anti-TB agent within the context of the obligate human host, this is complex and, until recently, has been severely limited by the available methodologies and models. Here, we discuss advances in analytical models and technologies which have enabled investigations of drug metabolism and pharmacokinetics (DMPK) for new TB drug development. In particular, we consider the potential to shift the focus of traditional pharmacokinetic-pharmacodynamic analyses away from plasma to a more specific "site of action" drug exposure as an essential criterion for drug development and the design of dosing strategies. Moreover, in summarising approaches to determine DMPK data for the "unit of infection" comprising host macrophage and intracellular bacillus, we evaluate the potential benefits of including these analyses at an early stage in the preclinical drug development algorithm. © 2018 IUBMB Life, 70(9):926-937, 2018.
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Affiliation(s)
- Lloyd Tanner
- SAMRC/NHLS/UCT Molecular Mycobacteriology Research Unit, Department of Pathology and Institute of Infectious Disease & Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Observatory, South Africa
- Division of Clinical Pharmacology, Department of Medicine, Faculty of Health Sciences, University of Cape Town, Observatory, South Africa
| | - Paolo Denti
- SAMRC/NHLS/UCT Molecular Mycobacteriology Research Unit, Department of Pathology and Institute of Infectious Disease & Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Observatory, South Africa
| | - Lubbe Wiesner
- SAMRC/NHLS/UCT Molecular Mycobacteriology Research Unit, Department of Pathology and Institute of Infectious Disease & Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Observatory, South Africa
| | - Digby F. Warner
- Division of Clinical Pharmacology, Department of Medicine, Faculty of Health Sciences, University of Cape Town, Observatory, South Africa
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Bhat ZS, Rather MA, Maqbool M, Lah HU, Yousuf SK, Ahmad Z. Cell wall: A versatile fountain of drug targets in Mycobacterium tuberculosis. Biomed Pharmacother 2017; 95:1520-1534. [PMID: 28946393 DOI: 10.1016/j.biopha.2017.09.036] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2017] [Revised: 09/07/2017] [Accepted: 09/10/2017] [Indexed: 12/18/2022] Open
Abstract
Tuberculosis is the leading infectious disease responsible for an estimated one and a half million human deaths each year around the globe. HIV-TB coinfection and rapid increase in the emergence of drug resistant forms of TB is a dangerous scenario. This underlines the urgent need for new drugs with novel mechanism of action. A plethora of literature exist that highlight the importance of enzymes involved in the biosynthesis of mycobacterial cell wall responsible for its survival, growth, permeability, virulence and resistance to antibiotics. Therefore, assembly of cell wall components is an attractive target for the development of chemotherapeutics against Mycobacterium tuberculosis. The aim of this review is to highlight novel sets of enzyme inhibitors that disrupt its cell wall biosynthetic pathway. These include the currently approved first and second line drugs, candidates in clinical trials and current structure activity guided endeavors of scientific community to identify new potent inhibitors with least cytotoxicity and better efficacy against emergence of drug resistance till date.
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Affiliation(s)
- Zubair Shanib Bhat
- Clinical Microbiology and PK/PD Division, Indian Institute of Integrative Medicine (IIIM), Campus, Sanat Nagar, Srinagar, Jammu & Kashmir 190005, India; Academy of Scientific and Innovative Research (AcSIR), CSIR- Indian Institute of Integrative Medicine (IIIM), Campus, Sanat Nagar, Srinagar, Jammu & Kashmir 190005, India.
| | - Muzafar Ahmad Rather
- Clinical Microbiology and PK/PD Division, Indian Institute of Integrative Medicine (IIIM), Campus, Sanat Nagar, Srinagar, Jammu & Kashmir 190005, India; Department of Biochemistry, University of Kashmir, Srinagar, Jammu & Kashmir 190006, India
| | - Mubashir Maqbool
- Clinical Microbiology and PK/PD Division, Indian Institute of Integrative Medicine (IIIM), Campus, Sanat Nagar, Srinagar, Jammu & Kashmir 190005, India; Department of Zoology, University of Kashmir, Srinagar, Jammu & Kashmir 190006, India
| | - Hafiz Ul Lah
- Medicinal Chemistry Division, Indian Institute of Integrative Medicine (IIIM), Campus, Sanat Nagar, Srinagar, Jammu & Kashmir 190005, India
| | - Syed Khalid Yousuf
- Academy of Scientific and Innovative Research (AcSIR), CSIR- Indian Institute of Integrative Medicine (IIIM), Campus, Sanat Nagar, Srinagar, Jammu & Kashmir 190005, India; Medicinal Chemistry Division, Indian Institute of Integrative Medicine (IIIM), Campus, Sanat Nagar, Srinagar, Jammu & Kashmir 190005, India
| | - Zahoor Ahmad
- Clinical Microbiology and PK/PD Division, Indian Institute of Integrative Medicine (IIIM), Campus, Sanat Nagar, Srinagar, Jammu & Kashmir 190005, India; Academy of Scientific and Innovative Research (AcSIR), CSIR- Indian Institute of Integrative Medicine (IIIM), Campus, Sanat Nagar, Srinagar, Jammu & Kashmir 190005, India.
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Wright CC, Hsu FF, Arnett E, Dunaj JL, Davidson PM, Pacheco SA, Harriff MJ, Lewinsohn DM, Schlesinger LS, Purdy GE. The Mycobacterium tuberculosis MmpL11 Cell Wall Lipid Transporter Is Important for Biofilm Formation, Intracellular Growth, and Nonreplicating Persistence. Infect Immun 2017; 85:e00131-17. [PMID: 28507063 PMCID: PMC5520431 DOI: 10.1128/iai.00131-17] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2017] [Accepted: 05/05/2017] [Indexed: 12/18/2022] Open
Abstract
The mycobacterial cell wall is crucial to the host-pathogen interface, because it provides a barrier against antibiotics and the host immune response. In addition, cell wall lipids are mycobacterial virulence factors. The mycobacterial membrane protein large (MmpL) proteins are cell wall lipid transporters that are important for basic mycobacterial physiology and Mycobacterium tuberculosis pathogenesis. MmpL3 and MmpL11 are conserved across pathogenic and nonpathogenic mycobacteria, a feature consistent with an important role in the basic physiology of the bacterium. MmpL3 is essential and transports trehalose monomycolate to the mycobacterial surface. In this report, we characterize the role of MmpL11 in M. tuberculosis. M. tuberculosismmpL11 mutants have altered biofilms associated with lower levels of mycolic acid wax ester and long-chain triacylglycerols than those for wild-type bacteria. While the growth rate of the mmpL11 mutant is similar to that of wild-type M. tuberculosis in macrophages, the mutant exhibits impaired survival in an in vitro granuloma model. Finally, we show that the survival or recovery of the mmpL11 mutant is impaired when it is incubated under conditions of nutrient and oxygen starvation. Our results suggest that MmpL11 and its cell wall lipid substrates are important for survival in the context of adaptive immune pressure and for nonreplicating persistence, both of which are critically important aspects of M. tuberculosis pathogenicity.
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Affiliation(s)
- Catherine C Wright
- Department of Molecular Microbiology and Immunology, Oregon Health & Science University, Portland, Oregon, USA
| | - Fong Fu Hsu
- Department of Internal Medicine, Mass Spectrometry Resource, Division of Endocrinology, Diabetes, Metabolism, and Lipid Research, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Eusondia Arnett
- Department of Microbial Infection and Immunity, Center for Microbial Interface Biology, The Ohio State University, Columbus, Ohio, USA
| | - Jennifer L Dunaj
- Department of Molecular Microbiology and Immunology, Oregon Health & Science University, Portland, Oregon, USA
| | - Patrick M Davidson
- Department of Molecular Microbiology and Immunology, Oregon Health & Science University, Portland, Oregon, USA
| | - Sophia A Pacheco
- Department of Molecular Microbiology and Immunology, Oregon Health & Science University, Portland, Oregon, USA
| | - Melanie J Harriff
- Portland Veterans Administration Medical Center, Portland, Oregon, USA
- Department of Pulmonary and Critical Care Medicine, Oregon Health & Science University, Portland, Oregon, USA
| | - David M Lewinsohn
- Department of Molecular Microbiology and Immunology, Oregon Health & Science University, Portland, Oregon, USA
- Portland Veterans Administration Medical Center, Portland, Oregon, USA
- Department of Pulmonary and Critical Care Medicine, Oregon Health & Science University, Portland, Oregon, USA
| | - Larry S Schlesinger
- Department of Microbial Infection and Immunity, Center for Microbial Interface Biology, The Ohio State University, Columbus, Ohio, USA
| | - Georgiana E Purdy
- Department of Molecular Microbiology and Immunology, Oregon Health & Science University, Portland, Oregon, USA
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Harvey DJ. Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update for 2011-2012. MASS SPECTROMETRY REVIEWS 2017; 36:255-422. [PMID: 26270629 DOI: 10.1002/mas.21471] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2014] [Accepted: 01/15/2015] [Indexed: 06/04/2023]
Abstract
This review is the seventh update of the original article published in 1999 on the application of MALDI mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2012. General aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, and fragmentation are covered in the first part of the review and applications to various structural types constitute the remainder. The main groups of compound are oligo- and poly-saccharides, glycoproteins, glycolipids, glycosides, and biopharmaceuticals. Much of this material is presented in tabular form. Also discussed are medical and industrial applications of the technique, studies of enzyme reactions, and applications to chemical synthesis. © 2015 Wiley Periodicals, Inc. Mass Spec Rev 36:255-422, 2017.
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Affiliation(s)
- David J Harvey
- Department of Biochemistry, Oxford Glycobiology Institute, University of Oxford, Oxford, OX1 3QU, UK
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Total synthesis of mycobacterial arabinogalactan containing 92 monosaccharide units. Nat Commun 2017; 8:14851. [PMID: 28300074 PMCID: PMC5357306 DOI: 10.1038/ncomms14851] [Citation(s) in RCA: 137] [Impact Index Per Article: 17.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Accepted: 02/07/2017] [Indexed: 01/21/2023] Open
Abstract
Carbohydrates are diverse bio-macromolecules with highly complex structures that are involved in numerous biological processes. Well-defined carbohydrates obtained by chemical synthesis are essential to the understanding of their functions. However, synthesis of carbohydrates is greatly hampered by its insufficient efficiency. So far, assembly of long carbohydrate chains remains one of the most challenging tasks for synthetic chemists. Here we describe a highly efficient assembly of a 92-mer polysaccharide by the preactivation-based one-pot glycosylation protocol. Several linear and branched oligosaccharide/polysaccharide fragments ranging from 5-mer to 31-mer in length have been rapidly constructed in one-pot manner, which enables the first total synthesis of a biologically important mycobacterial arabinogalactan through a highly convergent [31+31+30] coupling reaction. Our results show that the preactivation-based one-pot glycosylation protocol may provide access to the construction of long and complicated carbohydrate chains. Due to the vast number of potential isomers, the chemical synthesis of large carbohydrates is challenging. Here the authors report the synthesis of mycobacterial arabinogalactan, a biologically important natural product composed of 92 monosaccharide units, the largest synthetic polysaccharide to date.
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Vilchèze C, Kremer L. Acid-Fast Positive and Acid-Fast Negative Mycobacterium tuberculosis: The Koch Paradox. Microbiol Spectr 2017; 5:10.1128/microbiolspec.tbtb2-0003-2015. [PMID: 28337966 PMCID: PMC11687472 DOI: 10.1128/microbiolspec.tbtb2-0003-2015] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Indexed: 11/20/2022] Open
Abstract
Acid-fast (AF) staining, also known as Ziehl-Neelsen stain microscopic detection, developed over a century ago, is even today the most widely used diagnostic method for tuberculosis. Herein we present a short historical review of the evolution of AF staining methods and discuss Koch's paradox, in which non-AF tubercle bacilli can be detected in tuberculosis patients or in experimentally infected animals. The conversion of Mycobacterium tuberculosis from an actively growing, AF-positive form to a nonreplicating, AF-negative form during the course of infection is now well documented. The mechanisms of loss of acid-fastness are not fully understood but involve important metabolic processes, such as the accumulation of triacylglycerol-containing intracellular inclusions and changes in the composition and spatial architecture of the cell wall. Although the precise component(s) responsible for the AF staining method remains largely unknown, analysis of a series of genetically defined M. tuberculosis mutants, which are attenuated in mice, pointed to the primary role of mycolic acids and other cell wall-associated (glyco)lipids as molecular markers responsible for the AF property of mycobacteria. Further studies are now required to better describe the cell wall reorganization that occurs during dormancy and to develop new staining procedures that are not affected by such cell wall alterations and that are capable of detecting AF-negative cells.
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Affiliation(s)
- Catherine Vilchèze
- Howard Hughes Medical Institute, Department of Microbiology and Immunology, Albert Einstein College of Medicine, Bronx, NY 10461
| | - Laurent Kremer
- IRIM (ex-CPBS) UMR 9004, Infectious Disease Research Institute of Montpellier (IDRIM), Université de Montpellier, CNRS, 34293 Montpellier, France
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Abstract
Mycobacterium leprae must adopt a metabolic strategy and undergo various metabolic alterations upon infection to survive inside the human body for years in a dormant state. A change in lipid homeostasis upon infection is highly pronounced in Mycobacterium leprae. Lipids play an essential role in the survival and pathogenesis of mycobacteria. Lipids are present in several forms and serve multiple roles from being a source of nutrition, providing rigidity, evading the host immune response to serving as virulence factors, etc. The synthesis and degradation of lipids is a highly regulated process and is the key to future drug designing and diagnosis for mycobacteria. In the current review, an account of the distinct roles served by lipids, the mechanism of their synthesis and degradation has been elucidated.
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Affiliation(s)
- Gurkamaljit Kaur
- Research Scholar, Department of Biotechnology, Panjab University, Chandigarh 160014, India
| | - Jagdeep Kaur
- Department of Biotechnology, Panjab University, Chandigarh 160014, India
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Affiliation(s)
- Monika Jankute
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom;
| | - Jonathan A.G. Cox
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom;
| | - James Harrison
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom;
| | - Gurdyal S. Besra
- School of Biosciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom;
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GtrA Protein Rv3789 Is Required for Arabinosylation of Arabinogalactan in Mycobacterium tuberculosis. J Bacteriol 2015; 197:3686-97. [PMID: 26369580 DOI: 10.1128/jb.00628-15] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Accepted: 09/07/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED Mycobacterium tuberculosis possesses a thick and highly hydrophobic cell wall principally composed of a mycolyl-arabinogalactan-peptidoglycan complex, which is critical for survival and virulence. DprE1 is a well-characterized component of decaprenyl-phospho-ribose epimerase, which produces decaprenyl-phospho-arabinose (DPA) for the biosynthesis of mycobacterial arabinans. Upstream of dprE1 lies rv3789, which encodes a short transmembrane protein of the GtrA family, whose members are often involved in the synthesis of cell surface polysaccharides. We demonstrate that rv3789 and dprE1 are cotranscribed from a common transcription start site situated 64 bp upstream of rv3789. Topology mapping revealed four transmembrane domains in Rv3789 and a cytoplasmic C terminus consistent with structural models built using analysis of sequence coevolution. To investigate its role, we generated an unmarked rv3789 deletion mutant in M. tuberculosis. The mutant was characterized by impaired growth and abnormal cell morphology, since the cells were shorter and more swollen than wild-type cells. This phenotype likely stems from the decreased incorporation of arabinan into arabinogalactan and was accompanied by an accumulation of DPA. A role for Rv3789 in arabinan biosynthesis was further supported by its interaction with the priming arabinosyltransferase AftA, as demonstrated by a two-hybrid approach. Taken together, the data suggest that Rv3789 does not act as a DPA flippase but, rather, recruits AftA for arabinogalactan biosynthesis. IMPORTANCE Upstream of the essential dprE1 gene, encoding a key enzyme of the decaprenyl phospho-arabinose (DPA) pathway, lies rv3789, coding for a short transmembrane protein of unknown function. In this study, we demonstrated that rv3789 and dprE1 are cotranscribed from a common transcription start site located 64 bp upstream of rv3789 in M. tuberculosis. Furthermore, the deletion of rv3789 led to a reduction in arabinan content and to an accumulation of DPA, confirming that Rv3789 plays a role in arabinan biosynthesis. Topology mapping, structural modeling, and protein interaction studies suggest that Rv3789 acts as an anchor protein recruiting AftA, the first arabinosyl transferase. This investigation provides deeper insight into the mechanism of arabinan biosynthesis in mycobacteria.
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In silico epitope analysis of unique and membrane associated proteins from Mycobacterium avium subsp. paratuberculosis for immunogenicity and vaccine evaluation. J Theor Biol 2015; 384:1-9. [PMID: 26279134 DOI: 10.1016/j.jtbi.2015.08.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Revised: 07/27/2015] [Accepted: 08/04/2015] [Indexed: 11/24/2022]
Abstract
Mycobacterium avium subsp. paratuberculosis (MAP) is the etiologic agent of paratuberculosis disease affecting ruminants worldwide. The aim of this study was to identify potential candidate antigens and epitopes by bio and immuno-informatic tools which could be later evaluated as vaccines and/or diagnosis. 110 protein sequences were selected from MAP K-10 genome database: 48 classified as putative enzymes involved in surface polysaccharide and lipopolysaccharide synthesis, as membrane associated and secreted proteins, 32 as conserved membrane proteins, and 30 as absent from other mycobacterial genomes. These 110 proteins were preliminary screened for Major Histocompatibility Complex (MHC) class II affinity and promiscuity using ProPred program. In addition, subcellular localization and host protein homology was analyzed. From these analyses, 23 MAP proteins were selected for a more accurate inmunoinformatic analysis (i.e. T cell and B cell epitopes analysis) and for homology with mycobacterial proteins. Finally, eleven MAP proteins were identified as potential candidates for further immunogenic evaluation: six proteins (MAP0228c, MAP1239c, MAP2232, MAP3080, MAP3131 and MAP3890) were identified as presenting potential T cell epitopes, while 5 selected proteins (MAP0232c, MAP1240c, MAP1738, MAP2239 and MAP3641c) harbored a large numbers of epitopes predicted to induce both cell- and antibody-mediated immune responses. Moreover, immunogenicity of selected epitopes from MAP1239c were evaluated in IFN-γ release assay. In summary, eleven M. avium subsp. paratuberculosis proteins were identified by in silico analysis and need to be further evaluated for their immunodiagnostic and vaccine potential in field and mice model.
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Wheat WH, Dhouib R, Angala SK, Larrouy-Maumus G, Dobos K, Nigou J, Spencer JS, Jackson M. The presence of a galactosamine substituent on the arabinogalactan of Mycobacterium tuberculosis abrogates full maturation of human peripheral blood monocyte-derived dendritic cells and increases secretion of IL-10. Tuberculosis (Edinb) 2015; 95:476-89. [PMID: 26048627 DOI: 10.1016/j.tube.2015.04.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Accepted: 04/08/2015] [Indexed: 12/28/2022]
Abstract
Slow-growing and pathogenic Mycobacterium spp. are characterized by the presence of galactosamine (GalN) that modifies the interior branched arabinosyl residues of the arabinogalactan (AG) that is a major heteropolysaccharide cell wall component. The availability of null mutants of the polyprenyl-phospho-N-acetylgalactosaminyl synthase (Rv3631, PpgS) and the (N-acetyl-) galactosaminyl transferase (Rv3779) of Mycobacterium tuberculosis (Mtb) has provided a means to elucidate the role of the GalN substituent of AG in terms of host-pathogen interactions. Comparisons of treating human peripheral blood monocyte-derived dendritic cells (hPMC-DCs) with wild-type, Rv3631 and Rv3779 mutant strains of Mtb revealed increased expression of DC maturation markers, decreased affinity for a soluble DC-SIGN probe, reduced IL-10 secretion and increased TLR-2-mediated NF-κB activation among GalN-deficient Mtb strains compared to GalN-producing strains. Analysis of surface expression of a panel of defined or putative DC-SIGN ligands on both WT strains or either Rv3631 or Rv3779 mutant did not show significant differences suggesting that the role of the GalN substituent of AG may be to modulate access of the bacilli to immunologically-relevant receptor domains on DCs or contribute to higher ordered pathogen associated molecular pattern (PAMP)/pattern recognition receptor (PRR) interactions rather than the GalN-AG components having a direct immunological effect per se.
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Affiliation(s)
- William H Wheat
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523-1682, USA.
| | - Rabeb Dhouib
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523-1682, USA
| | - Shiva K Angala
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523-1682, USA
| | - Gérald Larrouy-Maumus
- CNRS, IPBS (Institut de Pharmacologie et de Biologie Structurale), Département Mécanismes Moléculaires des Infections Mycobactériennes, 205 route de Narbonne, F-31077 Toulouse, France; Université de Toulouse, UPS, IPBS, F-31077 Toulouse, France
| | - Karen Dobos
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523-1682, USA
| | - Jérôme Nigou
- CNRS, IPBS (Institut de Pharmacologie et de Biologie Structurale), Département Mécanismes Moléculaires des Infections Mycobactériennes, 205 route de Narbonne, F-31077 Toulouse, France; Université de Toulouse, UPS, IPBS, F-31077 Toulouse, France
| | - John S Spencer
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523-1682, USA
| | - Mary Jackson
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523-1682, USA
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CpsA, a LytR-CpsA-Psr Family Protein in Mycobacterium marinum, Is Required for Cell Wall Integrity and Virulence. Infect Immun 2015; 83:2844-54. [PMID: 25939506 DOI: 10.1128/iai.03081-14] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2014] [Accepted: 04/20/2015] [Indexed: 12/28/2022] Open
Abstract
LytR-CpsA-Psr family proteins play an important role in bacterial cell wall integrity. Although the pathogenic relevance of LytR-CpsA-Psr family proteins has been studied in a few bacterial pathogens, their function in mycobacteria remains uncharacterized. In this work, a transposon insertion mutant (cpsA::Tn) of Mycobacterium marinum was studied. We found that inactivation of CpsA altered bacterial colony morphology, sliding motility, cell surface hydrophobicity, and cell wall permeability. Besides, the cpsA mutant exhibited a decreased arabinogalactan content, indicating that CpsA plays a role in cell wall assembly. Moreover, the mutant shows impaired growth within macrophage cell lines and is severely attenuated in zebrafish larvae and adult zebrafish. Taken together, our results indicated that CpsA, a previously uncharacterized protein, is important for mycobacterial cell wall integrity and is required for mycobacterial virulence.
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Sechi LA, Dow CT. Mycobacterium avium ss. paratuberculosis Zoonosis - The Hundred Year War - Beyond Crohn's Disease. Front Immunol 2015; 6:96. [PMID: 25788897 PMCID: PMC4349160 DOI: 10.3389/fimmu.2015.00096] [Citation(s) in RCA: 103] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Accepted: 02/18/2015] [Indexed: 12/15/2022] Open
Abstract
The factitive role of Mycobacterium avium ss. paratuberculosis (MAP) in Crohn's disease has been debated for more than a century. The controversy is due to the fact that Crohn's disease is so similar to a disease of MAP-infected ruminant animals, Johne's disease; and, though MAP can be readily detected in the infected ruminants, it is much more difficult to detect in humans. Molecular techniques that can detect MAP in pathologic Crohn's specimens as well as dedicated specialty labs successful in culturing MAP from Crohn's patients have provided strong argument for MAP's role in Crohn's disease. Perhaps more incriminating for MAP as a zoonotic agent is the increasing number of diseases with which MAP has been related: Blau syndrome, type 1 diabetes, Hashimoto thyroiditis, and multiple sclerosis. In this article, we debate about genetic susceptibility to mycobacterial infection and human exposure to MAP; moreover, it suggests that molecular mimicry between protein epitopes of MAP and human proteins is a likely bridge between infection and these autoimmune disorders.
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Affiliation(s)
- Leonardo A Sechi
- Department of Biomedical Sciences, University of Sassari , Sassari , Italy
| | - Coad Thomas Dow
- McPherson Eye Research Institute, University of Wisconsin , Madison, WI , USA ; Chippewa Valley Eye Clinic , Eau Claire, WI , USA
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39
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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: 6.7] [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]
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Angala SK, Belardinelli JM, Huc-Claustre E, Wheat WH, Jackson M. The cell envelope glycoconjugates of Mycobacterium tuberculosis. Crit Rev Biochem Mol Biol 2014; 49:361-99. [PMID: 24915502 PMCID: PMC4436706 DOI: 10.3109/10409238.2014.925420] [Citation(s) in RCA: 122] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Tuberculosis (TB) remains the second most common cause of death due to a single infectious agent. The cell envelope of Mycobacterium tuberculosis (Mtb), the causative agent of the disease in humans, is a source of unique glycoconjugates and the most distinctive feature of the biology of this organism. It is the basis of much of Mtb pathogenesis and one of the major causes of its intrinsic resistance to chemotherapeutic agents. At the same time, the unique structures of Mtb cell envelope glycoconjugates, their antigenicity and essentiality for mycobacterial growth provide opportunities for drug, vaccine, diagnostic and biomarker development, as clearly illustrated by recent advances in all of these translational aspects. This review focuses on our current understanding of the structure and biogenesis of Mtb glycoconjugates with particular emphasis on one of the most intriguing and least understood aspect of the physiology of mycobacteria: the translocation of these complex macromolecules across the different layers of the cell envelope. It further reviews the rather impressive progress made in the last 10 years in the discovery and development of novel inhibitors targeting their biogenesis.
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Affiliation(s)
- Shiva Kumar Angala
- Mycobacteria Research Laboratories, Department of Microbiology, Immunology and Pathology, Colorado State University , Fort Collins, CO , USA
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Mycobacterial outer membrane is a lipid bilayer and the inner membrane is unusually rich in diacyl phosphatidylinositol dimannosides. Proc Natl Acad Sci U S A 2014; 111:4958-63. [PMID: 24639491 DOI: 10.1073/pnas.1403078111] [Citation(s) in RCA: 187] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Mycobacterium species, including the human pathogen Mycobacterium tuberculosis, are unique among Gram-positive bacteria in producing a complex cell wall that contains unusual lipids and functions as a permeability barrier. Lipids in the cell wall were hypothesized to form a bilayer or outer membrane that would prevent the entry of chemotherapeutic agents, but this could not be tested because of the difficulty in extracting only the cell-wall lipids. We used reverse micellar extraction to achieve this goal and carried out a quantitative analysis of both the cell wall and the inner membrane lipids of Mycobacterium smegmatis. We found that the outer leaflet of the outer membrane contains a similar number of hydrocarbon chains as the inner leaflet composed of mycolic acids covalently linked to cell-wall arabinogalactan, thus validating the outer membrane model. Furthermore, we found that preliminary extraction with reverse micelles permitted the subsequent complete extraction of inner membrane lipids with chloroform-methanol-water, revealing that one-half of hydrocarbon chains in this membrane are contributed by an unusual lipid, diacyl phosphatidylinositol dimannoside. The inner leaflet of this membrane likely is composed nearly entirely of this lipid. Because it contains four fatty acyl chains within a single molecule, it may produce a bilayer environment of unusually low fluidity and may slow the influx of drugs, contributing to the general drug resistance phenotype of mycobacteria.
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Combination of site directed mutagenesis and secondary structure analysis predicts the amino acids essential for stability of M. leprae MurE. Interdiscip Sci 2014; 6:40-7. [PMID: 24464703 DOI: 10.1007/s12539-014-0185-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Revised: 03/22/2013] [Accepted: 04/23/2013] [Indexed: 10/25/2022]
Abstract
The life-threatening infections caused by Mycobacterium leprae (Mle) remain a major challenge in developing countries as well as globe and there is a need to design potent anti-leprosy drugs. In our previous studies, ATP-dependent Mle-MurE ligase involved in biosynthesis of peptidoglycan was identified as one of the common drug targets, homology modeled and reported. In this work in silico site directed mutagenesis study was carried out on the homology modeled Mle-MurE ligase. This predicted the amino acids essential for stability. In addition, the distribution of these residues in different secondary structures and in active sites was analyzed. Finally, the role of the conserved residues in stability and function was analyzed. The availability of Mle-MurE ligase built model together with insights gained from stability studies and docking studies will promote the rational design of potent and selective Mle-MurE ligase inhibitors as anti-leprosy therapeutics.
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Differential detergent extraction of mycobacterium marinum cell envelope proteins identifies an extensively modified threonine-rich outer membrane protein with channel activity. J Bacteriol 2013; 195:2050-9. [PMID: 23457249 DOI: 10.1128/jb.02236-12] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A striking characteristic of mycobacteria is the presence of an unusual outer membrane which forms a thick permeability barrier and provides resistance to many antibiotics. Although specialized proteins must reside in this layer, only few mycolate outer membrane (MOM) proteins have been identified to date. Their discovery is complicated by difficulties in obtaining good separation of mycobacterial inner and outer membranes. During our efforts to identify novel mycobacterial outer membrane proteins (MOMPs), we discovered that we can enrich for MOMPs using differential solubilization of mycobacterial cell envelopes. Subsequently, these different fractions were analyzed by nano liquid chromatography-tandem mass spectrometry (nanoLC-MS/MS). This proteomic analysis confirmed that our marker proteins for inner membrane and MOM were found in their expected fractions and revealed a few interesting candidate MOMPs. A number of these putative MOMPs were further analyzed for their expression and localization in the cell envelope. One identified MOMP, MMAR_0617 of Mycobacterium marinum, was purified and demonstrated to form a large oligomeric complex. Importantly, this protein showed a clear single-channel conductance of 0.8 ± 0.1 ns upon reconstitution into artificial planar lipid bilayers. The most surprising feature of MMAR_0617 is a long C-terminal threonine-rich domain with extensive modifications. In summary, we have identified a novel mycobacterial outer membrane porin with unusual properties.
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Sarathy JP, Dartois V, Lee EJD. The role of transport mechanisms in mycobacterium tuberculosis drug resistance and tolerance. Pharmaceuticals (Basel) 2012; 5:1210-35. [PMID: 24281307 PMCID: PMC3816664 DOI: 10.3390/ph5111210] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2012] [Revised: 10/25/2012] [Accepted: 11/02/2012] [Indexed: 02/02/2023] Open
Abstract
In the fight against tuberculosis, cell wall permeation of chemotherapeutic agents remains a critical but largely unsolved question. Here we review the major mechanisms of small molecule penetration into and efflux from Mycobacterium tuberculosis and other mycobacteria, and outline how these mechanisms may contribute to the development of phenotypic drug tolerance and induction of drug resistance. M. tuberculosis is intrinsically recalcitrant to small molecule permeation thanks to its thick lipid-rich cell wall. Passive diffusion appears to account for only a fraction of total drug permeation. As in other bacterial species, influx of hydrophilic compounds is facilitated by water-filled open channels, or porins, spanning the cell wall. However, the diversity and density of M. tuberculosis porins appears lower than in enterobacteria. Besides, physiological adaptations brought about by unfavorable conditions are thought to reduce the efficacy of porins. While intracellular accumulation of selected drug classes supports the existence of hypothesized active drug influx transporters, efflux pumps contribute to the drug resistant phenotype through their natural abundance and diversity, as well as their highly inducible expression. Modulation of efflux transporter expression has been observed in phagocytosed, non-replicating persistent and multi-drug resistant bacilli. Altogether, M. tuberculosis has evolved both intrinsic properties and acquired mechanisms to increase its level of tolerance towards xenobiotic substances, by preventing or minimizing their entry. Understanding these adaptation mechanisms is critical to counteract the natural mechanisms of defense against toxic compounds and develop new classes of chemotherapeutic agents that positively exploit the influx and efflux pathways of mycobacteria.
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Affiliation(s)
- Jansy Passiflora Sarathy
- Novartis Institute for Tropical Diseases Pte Ltd, 10 Biopolis Road #05-01, Chromos, 138670, Singapore.
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Nonprotein structures from mycobacteria: emerging actors for tuberculosis control. Clin Dev Immunol 2012; 2012:917860. [PMID: 22611423 PMCID: PMC3352260 DOI: 10.1155/2012/917860] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Revised: 02/08/2012] [Accepted: 02/09/2012] [Indexed: 01/07/2023]
Abstract
Immune response to Mycobacterium tuberculosis, the causal agent of tuberculosis, is critical for protection. For many decades, consistent to classical biochemistry, most studies regarding immunity to the tubercle bacilli focused mainly on protein structures. But the atypical, highly impermeable and waxy coat of mycobacteria captured the interest of structural biologists very early, allowing the description of amazing molecules, such as previously unknown carbohydrates or fatty acids of astonishing lengths. From their discovery, cell wall components were identified as important structural pillars, but also as molecular motifs able to alter the human immune response. Recently, as new developments have emerged, classical conceptions of mycobacterial immune modulators have been giving place to unexpected discoveries that, at the turn of the last century, completely changed our perception of immunity vis-à-vis fat compounds. In this paper, current knowledge about chemical and ultrastructural features of mycobacterial cell-wall is overviewed, with an emphasis on the relationships between cell-wall nonpeptide molecules and immune response. Remarks regarding the potential of these molecules for the development of new tools against tuberculosis are finally discussed.
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Xiao JF, Zhou B, Ressom HW. Metabolite identification and quantitation in LC-MS/MS-based metabolomics. Trends Analyt Chem 2012; 32:1-14. [PMID: 22345829 PMCID: PMC3278153 DOI: 10.1016/j.trac.2011.08.009] [Citation(s) in RCA: 368] [Impact Index Per Article: 28.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Metabolomics aims at detection and quantitation of all metabolites in biological samples. The presence of metabolites with a wide variety of physicochemical properties and different levels of abundance challenges existing analytical platforms used for identification and quantitation of metabolites. Significant efforts have been made to improve analytical and computational methods for metabolomics studies.This review focuses on the use of liquid chromatography with tandem mass spectrometry (LC-MS/MS) for quantitative and qualitative metabolomics studies. It illustrates recent developments in computational methods for metabolite identification, including ion annotation, spectral interpretation and spectral matching. We also review selected reaction monitoring and high-resolution MS for metabolite quantitation. We discuss current challenges in metabolite identification and quantitation as well as potential solutions.
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Affiliation(s)
| | | | - Habtom W. Ressom
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University, 4000 Reservoir Rd., NW, Washington DC, 20057
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Abstract
Mycobacterium tuberculosis, the causative agent of tuberculosis, has a complex cellular envelope that comprises both the cytoplasmic membrane and the outer cell wall. Despite advances in elucidating the structural and biochemical composition of these features, the processes that ensure cell wall homeostasis remain poorly understood. New findings implicate the essential mycobacterial serine-threonine protein kinase (STPK), PknB, in regulating the formation of a regulatory complex that includes the integral membrane protein MviN, which is required for peptidoglycan biosynthesis, and a forkhead-associated (FHA) domain protein, FhaA. A model has emerged in which a peptidoglycan-derived muropeptide signal triggers the PknB-mediated phosphorylation of the MviN pseudokinase domain, which in turn recruits the FHA-containing regulatory protein to inhibit peptidoglycan biosynthesis at the cell poles and septum. In establishing PknB as central regulator of this pathway, the model reinforces the major role of this STPK network in the orchestration of fundamental mycobacterial processes, and, with the identification of MviN as having a catalytically inactive and highly divergent kinase homology domain, the model establishes a pseudokinase as a key player in cell wall metabolism.
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Affiliation(s)
- Digby F Warner
- MRC/NHLS/UCT Molecular Mycobacteriology Research Unit and DST/NRF Centre of Excellence for Biomedical Tuberculosis Research, Institute of Infectious Disease and Molecular Medicine, and Department of Clinical Laboratory Sciences, Faculty of Health Sciences, University of Cape Town, Private Bag X3, Rondebosch 7701, Cape Town, South Africa.
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