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Liu Y, Kaffah N, Pandor S, Sartain MJ, Larrouy-Maumus G. Ion mobility mass spectrometry for the study of mycobacterial mycolic acids. Sci Rep 2023; 13:10390. [PMID: 37369807 DOI: 10.1038/s41598-023-37641-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2023] [Accepted: 06/25/2023] [Indexed: 06/29/2023] Open
Abstract
Lipids are highly structurally diverse molecules involved in a wide variety of biological processes. The involvement of lipids is even more pronounced in mycobacteria, including the human pathogen Mycobacterium tuberculosis, which produces a highly complex and diverse set of lipids in the cell envelope. These lipids include mycolic acids, which are among the longest fatty acids in nature and can contain up to 90 carbon atoms. Mycolic acids are ubiquitously found in mycobacteria and are alpha branched and beta hydroxylated lipids. Discrete modifications, such as alpha, alpha', epoxy, methoxy, keto, and carboxy, characterize mycolic acids at the species level. Here, we used high precision ion mobility-mass spectrometry to build a database including 206 mass-resolved collision cross sections (CCSs) of mycolic acids originating from the strict human pathogen M. tuberculosis, the opportunistic strains M. abscessus, M. marinum and M. avium, and the nonpathogenic strain M. smegmatis. Primary differences between the mycolic acid profiles could be observed between mycobacterial species. Acyl tail length and modifications were the primary structural descriptors determining CCS magnitude. As a resource for researchers, this work provides a detailed catalogue of the mass-resolved collision cross sections for mycolic acids along with a workflow to generate and analyse the dataset generated.
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Affiliation(s)
- Yi Liu
- Centre for Bacterial Resistance Biology, Department of Life Sciences, Faculty of Natural Sciences, Imperial College London, London, SW7 2AZ, UK
| | - Nadhira Kaffah
- Centre for Bacterial Resistance Biology, Department of Life Sciences, Faculty of Natural Sciences, Imperial College London, London, SW7 2AZ, UK
| | | | | | - Gerald Larrouy-Maumus
- Centre for Bacterial Resistance Biology, Department of Life Sciences, Faculty of Natural Sciences, Imperial College London, London, SW7 2AZ, UK.
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2
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Holzheimer M, Buter J, Minnaard AJ. Chemical Synthesis of Cell Wall Constituents of Mycobacterium tuberculosis. Chem Rev 2021; 121:9554-9643. [PMID: 34190544 PMCID: PMC8361437 DOI: 10.1021/acs.chemrev.1c00043] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
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The pathogen Mycobacterium tuberculosis (Mtb), causing
tuberculosis disease, features an extraordinary
thick cell envelope, rich in Mtb-specific lipids,
glycolipids, and glycans. These cell wall components are often directly
involved in host–pathogen interaction and recognition, intracellular
survival, and virulence. For decades, these mycobacterial natural
products have been of great interest for immunology and synthetic
chemistry alike, due to their complex molecular structure and the
biological functions arising from it. The synthesis of many of these
constituents has been achieved and aided the elucidation of their
function by utilizing the synthetic material to study Mtb immunology. This review summarizes the synthetic efforts of a quarter
century of total synthesis and highlights how the synthesis layed
the foundation for immunological studies as well as drove the field
of organic synthesis and catalysis to efficiently access these complex
natural products.
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Affiliation(s)
- Mira Holzheimer
- Stratingh Institute for Chemistry, University of Groningen, 9747 AG Groningen, The Netherlands
| | - Jeffrey Buter
- Stratingh Institute for Chemistry, University of Groningen, 9747 AG Groningen, The Netherlands
| | - Adriaan J Minnaard
- Stratingh Institute for Chemistry, University of Groningen, 9747 AG Groningen, The Netherlands
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3
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Tahiri N, Fodran P, Jayaraman D, Buter J, Witte MD, Ocampo TA, Moody DB, Van Rhijn I, Minnaard AJ. Total Synthesis of a Mycolic Acid from
Mycobacterium tuberculosis. Angew Chem Int Ed Engl 2020. [DOI: 10.1002/ange.202000523] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Nabil Tahiri
- Stratingh Institute for ChemistryUniversity of Groningen Nijenborgh 7 9747 AG Groningen The Netherlands
| | - Peter Fodran
- Stratingh Institute for ChemistryUniversity of Groningen Nijenborgh 7 9747 AG Groningen The Netherlands
| | - Dhineshkumar Jayaraman
- Stratingh Institute for ChemistryUniversity of Groningen Nijenborgh 7 9747 AG Groningen The Netherlands
| | - Jeffrey Buter
- Stratingh Institute for ChemistryUniversity of Groningen Nijenborgh 7 9747 AG Groningen The Netherlands
| | - Martin D. Witte
- Stratingh Institute for ChemistryUniversity of Groningen Nijenborgh 7 9747 AG Groningen The Netherlands
| | - Tonatiuh A. Ocampo
- Brigham and Women's Hospital, Division of Rheumatology, Inflammation, and ImmunityHarvard Medical School, Hale BTM 60 Fenwood Road Boston MA 02115 USA
| | - D. Branch Moody
- Brigham and Women's Hospital, Division of Rheumatology, Inflammation, and ImmunityHarvard Medical School, Hale BTM 60 Fenwood Road Boston MA 02115 USA
| | - Ildiko Van Rhijn
- Brigham and Women's Hospital, Division of Rheumatology, Inflammation, and ImmunityHarvard Medical School, Hale BTM 60 Fenwood Road Boston MA 02115 USA
- Department of Infectious Diseases and ImmunologyFaculty of Veterinary MedicineUtrecht University Yalelaan 1 3584 CL Utrecht The Netherlands
| | - Adriaan J. Minnaard
- Stratingh Institute for ChemistryUniversity of Groningen Nijenborgh 7 9747 AG Groningen The Netherlands
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Tahiri N, Fodran P, Jayaraman D, Buter J, Witte MD, Ocampo TA, Moody DB, Van Rhijn I, Minnaard AJ. Total Synthesis of a Mycolic Acid from Mycobacterium tuberculosis. Angew Chem Int Ed Engl 2020; 59:7555-7560. [PMID: 32067294 PMCID: PMC7216993 DOI: 10.1002/anie.202000523] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2020] [Indexed: 11/22/2022]
Abstract
In Mycobacterium tuberculosis, mycolic acids and their glycerol, glucose, and trehalose esters ("cord factor") form the main part of the mycomembrane. Despite their first isolation almost a century ago, full stereochemical evaluation is lacking, as is a scalable synthesis required for accurate immunological, including vaccination, studies. Herein, we report an efficient, convergent, gram-scale synthesis of four stereo-isomers of a mycolic acid and its glucose ester. Binding to the antigen presenting protein CD1b and T cell activation studies are used to confirm the antigenicity of the synthetic material. The absolute stereochemistry of the syn-methoxy methyl moiety in natural material is evaluated by comparing its optical rotation with that of synthetic material.
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Affiliation(s)
- Nabil Tahiri
- Stratingh Institute for ChemistryUniversity of GroningenNijenborgh 79747 AGGroningenThe Netherlands
| | - Peter Fodran
- Stratingh Institute for ChemistryUniversity of GroningenNijenborgh 79747 AGGroningenThe Netherlands
| | - Dhineshkumar Jayaraman
- Stratingh Institute for ChemistryUniversity of GroningenNijenborgh 79747 AGGroningenThe Netherlands
| | - Jeffrey Buter
- Stratingh Institute for ChemistryUniversity of GroningenNijenborgh 79747 AGGroningenThe Netherlands
| | - Martin D. Witte
- Stratingh Institute for ChemistryUniversity of GroningenNijenborgh 79747 AGGroningenThe Netherlands
| | - Tonatiuh A. Ocampo
- Brigham and Women's Hospital, Division of Rheumatology, Inflammation, and ImmunityHarvard Medical School, Hale BTM60 Fenwood RoadBostonMA02115USA
| | - D. Branch Moody
- Brigham and Women's Hospital, Division of Rheumatology, Inflammation, and ImmunityHarvard Medical School, Hale BTM60 Fenwood RoadBostonMA02115USA
| | - Ildiko Van Rhijn
- Brigham and Women's Hospital, Division of Rheumatology, Inflammation, and ImmunityHarvard Medical School, Hale BTM60 Fenwood RoadBostonMA02115USA
- Department of Infectious Diseases and ImmunologyFaculty of Veterinary MedicineUtrecht UniversityYalelaan 13584 CLUtrechtThe Netherlands
| | - Adriaan J. Minnaard
- Stratingh Institute for ChemistryUniversity of GroningenNijenborgh 79747 AGGroningenThe Netherlands
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5
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Study of the conformational behaviour of trehalose mycolates by FT-IR spectroscopy. Chem Phys Lipids 2019; 223:104789. [DOI: 10.1016/j.chemphyslip.2019.104789] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2019] [Revised: 06/22/2019] [Accepted: 06/25/2019] [Indexed: 11/24/2022]
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Groenewald W, Parra-Cruz RA, Jäger CM, Croft AK. Revealing solvent-dependent folding behavior of mycolic acids from Mycobacterium tuberculosis by advanced simulation analysis. J Mol Model 2019; 25:68. [PMID: 30762132 PMCID: PMC7019640 DOI: 10.1007/s00894-019-3943-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 01/24/2019] [Indexed: 11/09/2022]
Abstract
Mycobacterium tuberculosis remains a persistent pathogen, partly due to its lipid rich cell wall, of which mycolic acids (MAs) are a major component. The fluidity and conformational flexibilities of different MAs in the bacterial cell wall significantly influence its properties, function, and observed pathogenicity; thus, a proper conformational description of different MAs in different environments (e.g., in vacuum, in solution, in monolayers) can inform about their potential role in the complex setup of the bacterial cell wall. Previously, we have shown that molecular dynamics (MD) simulations of MA folding in vacuo can be used to characterize MA conformers in seven groupings relating to bending at the functional groups (W, U and Z-conformations). Providing a new OPLS-based forcefield parameterization for the critical cyclopropyl group of MAs and extensive simulations in explicit solvents (TIP4P water, hexane), we now present a more complete picture of MA folding properties together with improved simulation analysis techniques. We show that the 'WUZ' distance-based analysis can be used to pinpoint conformers with hairpin bends at the functional groups, with these conformers constituting only a fraction of accessible conformations. Applying principle component analysis (PCA) and refinement using free energy landscapes (FELs), we are able to discriminate a complete and unique set of conformational preferences for representative alpha-, methoxy- and keto-MAs, with overall preference for folded conformations. A control backbone-MA without any mero-chain functional groups showed significantly less folding in the mero-chain, confirming the role of functionalization in directing folding. Keto-MA showed the highest percentage of WUZ-type conformations and, in particular, a tendency to fold at its alpha-methyl trans-cyclopropane group, in agreement with results from Villeneuve et al. MAs demonstrate similar folding in vacuum and water, with a majority of folded conformations around the W-conformation, although the molecules are more flexible in vacuum than in water. Exchange between conformations, with a disperse distribution that includes unfolded conformers, is common in hexane for all MAs, although with more organization for Keto-MA. Globular, folded conformations are newly defined and may be specifically relevant in biofilms. Graphical abstract Through advanced simulation analysis, including principle component analysis and free energy landscapes, we reveal detailed physical insights into the solvent-dependant folding behavior of mycolic acids from M. tb.
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Affiliation(s)
- Wilma Groenewald
- School of Chemistry, Bangor University, Bangor, Gwynedd, LL57 2UW, UK
| | - Ricardo A Parra-Cruz
- Department of Chemical and Environmental Engineering, University of Nottingham, University Park, Nottingham, NG7 2RD, UK
| | - Christof M Jäger
- Department of Chemical and Environmental Engineering, University of Nottingham, University Park, Nottingham, NG7 2RD, UK
| | - Anna K Croft
- Department of Chemical and Environmental Engineering, University of Nottingham, University Park, Nottingham, NG7 2RD, UK.
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Villeneuve M, Noguchi H. Roles of α-methyl trans-cyclopropane groups in behavior of mixed mycolic acid monolayers. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2019; 1861:441-448. [DOI: 10.1016/j.bbamem.2018.10.019] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Revised: 09/15/2018] [Accepted: 10/16/2018] [Indexed: 01/01/2023]
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Ranchod H, Ndlandla F, Lemmer Y, Beukes M, Niebuhr J, Al-Dulayymi J, Wemmer S, Fehrsen J, Baird M, Verschoor J. The antigenicity and cholesteroid nature of mycolic acids determined by recombinant chicken antibodies. PLoS One 2018; 13:e0200298. [PMID: 30092023 PMCID: PMC6084858 DOI: 10.1371/journal.pone.0200298] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2018] [Accepted: 06/22/2018] [Indexed: 11/24/2022] Open
Abstract
Mycolic acids (MA) are major, species-specific lipid components of Mycobacteria and related genera. In Mycobacterium tuberculosis, it is made up of alpha-, methoxy- and keto-MA, each with specific biological functions and conformational characteristics. Antibodies in tuberculosis (TB) patient sera respond differently towards the three MA classes and were reported to cross-react with cholesterol. To understand the antigenicity and cholesterol cross-reactivity of MA, we generated three different chicken -derived phage-displayed single-chain variable fragments (scFv) that reacted similarly towards the natural mixture of MA, but the first recognized all three classes of chemically synthetic MAs, the second only the two oxygenated types of MAs and the third only methoxy MA. The cholesterol cross-reactivity was investigated after grafting each of the three scFv types onto two configurations of constant chain domains–CH1-4 and CH2-4. Weak but significant cross-reactivity with cholesterol was found only with CH2-4 versions, notably those two that were also able to recognize the trans-keto MA. The cholesteroid nature of mycobacterial mycolic acids therefore seems to be determined by the trans-keto MA subclass. The significantly weaker binding to cholesterol in comparison to MA confirms the potential TB diagnostic application of these antibodies.
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Affiliation(s)
- Heena Ranchod
- Polymers and Composites, Council for Scientific and Industrial Research, Pretoria, South Africa
- Department Biochemistry, University of Pretoria, Pretoria, South Africa
- * E-mail:
| | - Fortunate Ndlandla
- Polymers and Composites, Council for Scientific and Industrial Research, Pretoria, South Africa
- Department Biochemistry, University of Pretoria, Pretoria, South Africa
| | - Yolandy Lemmer
- Polymers and Composites, Council for Scientific and Industrial Research, Pretoria, South Africa
| | - Mervyn Beukes
- Department Biochemistry, University of Pretoria, Pretoria, South Africa
| | - Johann Niebuhr
- Department Biochemistry, University of Pretoria, Pretoria, South Africa
| | | | - Susan Wemmer
- Serology and Immunochemistry, Vaccines and Diagnostics Development Programme, Agricultural Research Council—Onderstepoort Veterinary Institute, Pretoria, South Africa
| | - Jeanni Fehrsen
- Serology and Immunochemistry, Vaccines and Diagnostics Development Programme, Agricultural Research Council—Onderstepoort Veterinary Institute, Pretoria, South Africa
| | - Mark Baird
- School of Chemistry, Bangor University, Wales, United Kingdom
| | - Jan Verschoor
- Department Biochemistry, University of Pretoria, Pretoria, South Africa
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9
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Jones A, Pitts M, Al Dulayymi JR, Gibbons J, Ramsay A, Goletti D, Gwenin CD, Baird MS. New synthetic lipid antigens for rapid serological diagnosis of tuberculosis. PLoS One 2017; 12:e0181414. [PMID: 28806423 PMCID: PMC5555574 DOI: 10.1371/journal.pone.0181414] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2016] [Accepted: 07/01/2017] [Indexed: 01/30/2023] Open
Abstract
Background During pulmonary tuberculosis (PTB) antibodies are generated to trehalose esters of mycolic acids which are cell wall lipids of Mycobacterium tuberculosis (Mtb). Attempts have been made to use these complex natural mixtures in serological tests for PTB diagnosis. Aim The aim of this work was to determine whether a serological test based on a panel of defined individual trehalose esters of characteristic synthetic mycolic acids has improved diagnostic accuracy in distinguishing patients with culture positive PTB from individuals who were Mtb culture negative. Method One hundred serum samples from well-characterized patients with presumptive tuberculosis, and diagnosed as having pulmonary smear and culture positive TB, or being culture and smear negative were evaluated by ELISA using different combinations of synthetic antigens and secondary antibodies. Using cut-off values determined from these samples, we validated this study blind in samples from a further 249 presumptive TB patients. Results With the first 100 samples, detailed responses depended both on the precise structure of the antigen and on the secondary antibody. Using a single antigen, a sensitivity/specificity combination for smear and culture positive PTB detection of 85 and 88% respectively was achieved; this increased to 96% and 95% respectively by a statistical combination of the results with seven antigens. In the blind study a sensitivity/specificity of 87% and 83% was reached with a single antigen. With some synthetic antigens, the responses from all 349 samples were significantly better than those with the natural mixture. Combining the results for seven antigens allowed a distinction between culture positive and negative with a ROC AUC of 0.95. Conclusion We have identified promising antigen candidates for serological assays that could be used to diagnose PTB and which could be the basis of a much-needed, simple, rapid diagnostic test that would bring care closer to communities.
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Affiliation(s)
- Alison Jones
- School of Chemistry, Bangor University, Bangor, Gwynedd, Wales, United Kingdom
| | - Mark Pitts
- School of Chemistry, Bangor University, Bangor, Gwynedd, Wales, United Kingdom
| | | | - James Gibbons
- School of Environment, Natural Resources and Geography, Bangor University, Bangor, Gwynedd, Wales, United Kingdom
| | - Andrew Ramsay
- Special Programme for Research and Training in Tropical Diseases (TDR), World Health Organisation, Geneva, Switzerland
- University of St Andrews Medical School, St. Andrews, Scotland, United Kingdom
| | - Delia Goletti
- Translational Research Unit, Department of Epidemiology and Preclinical Research, ‘L. Spallanzani’ National Institute for Infectious Diseases, Rome, Italy
| | | | - Mark S. Baird
- School of Chemistry, Bangor University, Bangor, Gwynedd, Wales, United Kingdom
- * E-mail:
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Fineran P, Lloyd-Evans E, Lack NA, Platt N, Davis LC, Morgan AJ, Höglinger D, Tatituri RVV, Clark S, Williams IM, Tynan P, Al Eisa N, Nazarova E, Williams A, Galione A, Ory DS, Besra GS, Russell DG, Brenner MB, Sim E, Platt FM. Pathogenic mycobacteria achieve cellular persistence by inhibiting the Niemann-Pick Type C disease cellular pathway. Wellcome Open Res 2016. [PMID: 28008422 DOI: 10.12688/wellcomeopenres.10036.1] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
BACKGROUND Tuberculosis remains a major global health concern. The ability to prevent phagosome-lysosome fusion is a key mechanism by which intracellular mycobacteria, including Mycobacterium tuberculosis, achieve long-term persistence within host cells. The mechanisms underpinning this key intracellular pro-survival strategy remain incompletely understood. Host macrophages infected with persistent mycobacteria share phenotypic similarities with cells taken from patients suffering from Niemann-Pick Disease Type C (NPC), a rare lysosomal storage disease in which endocytic trafficking defects and lipid accumulation within the lysosome lead to cell dysfunction and cell death. We investigated whether these shared phenotypes reflected an underlying mechanistic connection between mycobacterial intracellular persistence and the host cell pathway dysfunctional in NPC. METHODS The induction of NPC phenotypes in macrophages from wild-type mice or obtained from healthy human donors was assessed via infection with mycobacteria and subsequent measurement of lipid levels and intracellular calcium homeostasis. The effect of NPC therapeutics on intracellular mycobacterial load was also assessed. RESULTS Macrophages infected with persistent intracellular mycobacteria phenocopied NPC cells, exhibiting accumulation of multiple lipid types, reduced lysosomal Ca2+ levels, and defects in intracellular trafficking. These NPC phenotypes could also be induced using only lipids/glycomycolates from the mycobacterial cell wall. These data suggest that persistent intracellular mycobacteria inhibit the NPC pathway, likely via inhibition of the NPC1 protein, and subsequently induce altered acidic store Ca2+ homeostasis. Reduced lysosomal calcium levels may provide a mechanistic explanation for the reduced levels of phagosome-lysosome fusion in mycobacterial infection. Treatments capable of correcting defects in NPC mutant cells via modulation of host cell calcium were of benefit in promoting clearance of mycobacteria from infected host cells. CONCLUSION These findings provide a novel mechanistic explanation for mycobacterial intracellular persistence, and suggest that targeting interactions between the mycobacteria and host cell pathways may provide a novel avenue for development of anti-TB therapies.
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Affiliation(s)
- Paul Fineran
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - Emyr Lloyd-Evans
- Department of Pharmacology, University of Oxford, Oxford, UK.,School of Biosciences, Cardiff University, Cardiff, UK
| | - Nathan A Lack
- Department of Pharmacology, University of Oxford, Oxford, UK.,School of Medicine, Koç University, Istanbul, Turkey
| | - Nick Platt
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - Lianne C Davis
- Department of Pharmacology, University of Oxford, Oxford, UK
| | | | - Doris Höglinger
- Department of Pharmacology, University of Oxford, Oxford, UK
| | | | | | - Ian M Williams
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - Patricia Tynan
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - Nada Al Eisa
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - Evgeniya Nazarova
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, USA
| | | | - Antony Galione
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - Daniel S Ory
- Diabetic Cardiovascular Disease Center, Washington University School of Medicine, St. Louis, USA
| | - Gurdyal S Besra
- School of Biosciences, University of Birmingham, Birmingham, UK
| | - David G Russell
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, USA
| | - Michael B Brenner
- Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, USA
| | - Edith Sim
- Department of Pharmacology, University of Oxford, Oxford, UK.,Faculty of Science Engineering and Computing, Kingston University, Kingston upon Thames, UK
| | - Frances M Platt
- Department of Pharmacology, University of Oxford, Oxford, UK
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11
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Fineran P, Lloyd-Evans E, Lack NA, Platt N, Davis LC, Morgan AJ, Höglinger D, Tatituri RVV, Clark S, Williams IM, Tynan P, Al Eisa N, Nazarova E, Williams A, Galione A, Ory DS, Besra GS, Russell DG, Brenner MB, Sim E, Platt FM. Pathogenic mycobacteria achieve cellular persistence by inhibiting the Niemann-Pick Type C disease cellular pathway. Wellcome Open Res 2016; 1:18. [PMID: 28008422 PMCID: PMC5172425 DOI: 10.12688/wellcomeopenres.10036.2] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/14/2017] [Indexed: 12/17/2022] Open
Abstract
BACKGROUND Tuberculosis remains a major global health concern. The ability to prevent phagosome-lysosome fusion is a key mechanism by which intracellular mycobacteria, including Mycobacterium tuberculosis, achieve long-term persistence within host cells. The mechanisms underpinning this key intracellular pro-survival strategy remain incompletely understood. Host macrophages infected with persistent mycobacteria share phenotypic similarities with cells taken from patients suffering from Niemann-Pick Disease Type C (NPC), a rare lysosomal storage disease in which endocytic trafficking defects and lipid accumulation within the lysosome lead to cell dysfunction and cell death. We investigated whether these shared phenotypes reflected an underlying mechanistic connection between mycobacterial intracellular persistence and the host cell pathway dysfunctional in NPC. METHODS The induction of NPC phenotypes in macrophages from wild-type mice or obtained from healthy human donors was assessed via infection with mycobacteria and subsequent measurement of lipid levels and intracellular calcium homeostasis. The effect of NPC therapeutics on intracellular mycobacterial load was also assessed. RESULTS Macrophages infected with persistent intracellular mycobacteria phenocopied NPC cells, exhibiting accumulation of multiple lipid types, reduced lysosomal Ca2+ levels, and defects in intracellular trafficking. These NPC phenotypes could also be induced using only lipids/glycomycolates from the mycobacterial cell wall. These data suggest that persistent intracellular mycobacteria inhibit the NPC pathway, likely via inhibition of the NPC1 protein, and subsequently induce altered acidic store Ca2+ homeostasis. Reduced lysosomal calcium levels may provide a mechanistic explanation for the reduced levels of phagosome-lysosome fusion in mycobacterial infection. Treatments capable of correcting defects in NPC mutant cells via modulation of host cell calcium were of benefit in promoting clearance of mycobacteria from infected host cells. CONCLUSION These findings provide a novel mechanistic explanation for mycobacterial intracellular persistence, and suggest that targeting interactions between the mycobacteria and host cell pathways may provide a novel avenue for development of anti-TB therapies.
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Affiliation(s)
- Paul Fineran
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - Emyr Lloyd-Evans
- Department of Pharmacology, University of Oxford, Oxford, UK
- School of Biosciences, Cardiff University, Cardiff, UK
| | - Nathan A. Lack
- Department of Pharmacology, University of Oxford, Oxford, UK
- School of Medicine, Koç University, Istanbul, Turkey
| | - Nick Platt
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - Lianne C. Davis
- Department of Pharmacology, University of Oxford, Oxford, UK
| | | | - Doris Höglinger
- Department of Pharmacology, University of Oxford, Oxford, UK
| | | | | | - Ian M. Williams
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - Patricia Tynan
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - Nada Al Eisa
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - Evgeniya Nazarova
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, USA
| | | | - Antony Galione
- Department of Pharmacology, University of Oxford, Oxford, UK
| | - Daniel S. Ory
- Diabetic Cardiovascular Disease Center, Washington University School of Medicine, St. Louis, USA
| | | | - David G. Russell
- Department of Microbiology and Immunology, College of Veterinary Medicine, Cornell University, Ithaca, USA
| | - Michael B. Brenner
- Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, USA
| | - Edith Sim
- Department of Pharmacology, University of Oxford, Oxford, UK
- Faculty of Science Engineering and Computing, Kingston University, Kingston upon Thames, UK
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12
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F420H2 Is Required for Phthiocerol Dimycocerosate Synthesis in Mycobacteria. J Bacteriol 2016; 198:2020-8. [PMID: 27185825 DOI: 10.1128/jb.01035-15] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Accepted: 05/06/2016] [Indexed: 12/17/2022] Open
Abstract
UNLABELLED Phthiocerol dimycocerosates (PDIM) are a group of cell surface-associated apolar lipids of Mycobacterium tuberculosis and closely related mycobacteria, such as Mycobacterium bovis and Mycobacterium leprae A characteristic methoxy group of these lipids is generated from the methylation of a hydroxyl group of the direct precursors, the phthiotriols. The precursors arise from the reduction of phthiodiolones, the keto intermediates, by a ketoreductase. The putative phthiodiolone ketoreductase (PKR) is encoded by Rv2951c in M. tuberculosis and BCG_2972c in M. bovis BCG, and these open reading frames (ORFs) encode identical amino acid sequences. We investigated the cofactor requirement of the BCG_2972c protein. A comparative analysis based on the crystallographic structures of similar enzymes identified structural elements for binding of coenzyme F420 and hydrophobic phthiodiolones in PKR. Coenzyme F420 is a deazaflavin coenzyme that serves several key functions in pathogenic and nonpathogenic mycobacteria. We found that an M. bovis BCG mutant lacking F420-dependent glucose-6-phosphate dehydrogenase (Fgd), which generates F420H2 (glucose-6-phosphate + F420 → 6-phosphogluconate + F420H2), was devoid of phthiocerols and accumulated phthiodiolones. When the mutant was provided with F420H2, a broken-cell slurry of the mutant converted accumulated phthiodiolones to phthiocerols; F420H2 was generated in situ from F420 and glucose-6-phosphate by the action of Fgd. Thus, the reaction mixture was competent in reducing phthiodiolones to phthiotriols (phthiodiolones + F420H2 → phthiotriols + F420), which were then methylated to phthiocerols. These results established the mycobacterial phthiodiolone ketoreductase as an F420H2-dependent enzyme (fPKR). A phylogenetic analysis of close homologs of fPKR revealed potential F420-dependent lipid-modifying enzymes in a broad range of mycobacteria. IMPORTANCE Mycobacterium tuberculosis is the causative agent of tuberculosis, and phthiocerol dimycocerosates (PDIM) protect this pathogen from the early innate immune response of an infected host. Thus, the PDIM synthesis system is a potential target for the development of effective treatments for tuberculosis. The current study shows that a PDIM synthesis enzyme is dependent on the coenzyme F420 F420 is universally present in mycobacteria and absent in humans. This finding expands the number of experimentally validated F420-dependent enzymes in M. tuberculosis to six, each of which helps the pathogen to evade killing by the host immune system, and one of which activates an antituberculosis drug, PA-824. This work also has relevance to leprosy, since similar waxy lipids are found in Mycobacterium leprae.
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Mohammed MO, Baird MS, Al Dulayymi JR, Jones A, Gwenin CD. Arabino mycolates from synthetic mycolic acids. Tetrahedron 2016. [DOI: 10.1016/j.tet.2016.03.083] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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14
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Ndlandla FL, Ejoh V, Stoltz AC, Naicker B, Cromarty AD, van Wyngaardt S, Khati M, Rotherham LS, Lemmer Y, Niebuhr J, Baumeister CR, Al Dulayymi JR, Swai H, Baird MS, Verschoor JA. Standardization of natural mycolic acid antigen composition and production for use in biomarker antibody detection to diagnose active tuberculosis. J Immunol Methods 2016; 435:50-9. [PMID: 27247168 DOI: 10.1016/j.jim.2016.05.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Revised: 04/21/2016] [Accepted: 05/24/2016] [Indexed: 10/21/2022]
Abstract
Mycobacterium tuberculosis, the causative agent of tuberculosis, is characterized by the abundance of species specific, antigenic cell wall lipids called mycolic acids. These wax-like molecules all share an identical, amphiphilic mycolic motif, but have different functional groups in a long hydrophobic hydrocarbon mero-chain that divide them into three main classes: alpha-, keto- and methoxy-mycolic acids. Whereas alpha-mycolic acids constitutively maintain an abundance of around 50%, the ratio of methoxy- to keto-mycolic acid types may vary depending on, among other things, the growth stage of M. tuberculosis. In human patients, antibodies to mycolic acids have shown potential as diagnostic serum biomarkers for active TB. Variations in mycolic acid composition affect the antigenic properties and can potentially compromise the precision of detection of anti-mycolic acids antibodies in patient sera to natural mixtures. We demonstrate this here with combinations of synthetic mycolic acid antigens, tested against TB patient and control sera. Combinations of methoxy- and α-mycolic acids are more antigenic than combinations of keto- and α-mycolic acids, showing the former to give a more sensitive test for TB biomarker antibodies. Natural mixtures of mycolic acids isolated from mature cultures of M. tuberculosis H37Rv give the same sensitivity as that with synthetic methoxy- and α-mycolic acids in combination, in a surface plasmon resonance inhibition biosensor test. To ensure that the antigenic activity of isolates of natural mycolic acids is reproducible, we cultured M. tuberculosis H37Rv on Middlebrook 7H10 solid agar plates to stationary growth phase in a standardized, optimal way. The proportions of mycolic acid classes in various batches of the isolates prepared from these cultures were compared to a commercially available natural mycolic acid isolate. LC-MS/MS and NMR data for quantitation of mycolic acids class compositions show that the variation in batches is small, suggesting that the quality of the results for anti-mycolic acid antibody detection in the TB patients should not be affected by different batches of natural mycolic acid antigens if prepared in a standard way.
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Affiliation(s)
- F L Ndlandla
- Polymers and Composites, Council for Scientific and Industrial Research, Pretoria, South Africa; Department of Biochemistry, University of Pretoria, South Africa
| | - V Ejoh
- Department of Biochemistry, University of Pretoria, South Africa
| | - A C Stoltz
- Division of Infectious Diseases, Faculty of Health Sciences, University of Pretoria, South Africa
| | - B Naicker
- Polymers and Composites, Council for Scientific and Industrial Research, Pretoria, South Africa; Department of Pharmacology, Faculty of Health Sciences, University of Pretoria, South Africa
| | - A D Cromarty
- Department of Pharmacology, Faculty of Health Sciences, University of Pretoria, South Africa
| | - S van Wyngaardt
- Department of Biochemistry, University of Pretoria, South Africa
| | - M Khati
- Biosciences, Council for Scientific and Industrial Research, Pretoria, South Africa
| | - L S Rotherham
- Biosciences, Council for Scientific and Industrial Research, Pretoria, South Africa
| | - Y Lemmer
- Polymers and Composites, Council for Scientific and Industrial Research, Pretoria, South Africa
| | - J Niebuhr
- Department of Biochemistry, University of Pretoria, South Africa
| | - C R Baumeister
- Department of Biochemistry, University of Pretoria, South Africa
| | | | - H Swai
- Polymers and Composites, Council for Scientific and Industrial Research, Pretoria, South Africa
| | - M S Baird
- School of Chemistry, Bangor University, Wales, UK
| | - J A Verschoor
- Department of Biochemistry, University of Pretoria, South Africa
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Taniguchi K, Miyatake Y, Hayashi D, Takami A, Itoh S, Yamamoto S, Hida S, Onozaki K, Takii T. Early-shared Mycobacterium bovis bacillus Calmette-Guérin sub-strains induce Th1 cytokine production in vivo. Microbiol Immunol 2015; 59:684-9. [PMID: 26399380 DOI: 10.1111/1348-0421.12326] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Revised: 09/11/2015] [Accepted: 09/17/2015] [Indexed: 01/20/2023]
Abstract
Interleukin-12 is one of the cytokines that induce acquired immunity by progressing the differentiation of T cells. When antigens are presented by APCs, including macrophages and DCs, T cells are activated and produce the Th1 cytokines IL-2 and IFN-γ. We have previously reported greater IL-12 production from macrophages infected with early-shared BCG sub-strains (ex. BCG-Japan, -Sweden) than from those infected with late-shared BCG (ex. BCG-Pasteur and -Connaught) . In this study, we investigated the Th1 cytokine-inducing activity of splenocytes co-cultured with BCG-infected DCs. Early-shared BCG-infected DCs produced IL-12 and TNF-α⋅ Furthermore, when they were co-cultured with purified protein derivative-stimulated DCs, the splenocytes of mice immunized with BCG-Tokyo/Japan produced more Th1 cytokine than did those of mice immunized with BCG-Connaught. In conclusion, early-shared BCG sub-strains more strongly induce Th1 cytokine production in vivo. This study provides basic information to inform the selection of candidates for primary vaccination.
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Affiliation(s)
- Keiichi Taniguchi
- Department of Molecular Health Sciences, Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe, Mizuho-ku, Nagoya 467-8603
| | - Yuuji Miyatake
- Department of Molecular Health Sciences, Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe, Mizuho-ku, Nagoya 467-8603
| | - Daisuke Hayashi
- Japan BCG Laboratory, 3-1-5 Matsuyama, Kiyose, Tokyo 204-0022, Japan
| | - Atsuro Takami
- Department of Molecular Health Sciences, Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe, Mizuho-ku, Nagoya 467-8603
| | - Saotomo Itoh
- Department of Molecular Health Sciences, Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe, Mizuho-ku, Nagoya 467-8603
| | - Saburo Yamamoto
- Japan BCG Laboratory, 3-1-5 Matsuyama, Kiyose, Tokyo 204-0022, Japan
| | - Shigeaki Hida
- Department of Molecular Health Sciences, Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe, Mizuho-ku, Nagoya 467-8603
| | - Kikuo Onozaki
- Department of Molecular Health Sciences, Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe, Mizuho-ku, Nagoya 467-8603
| | - Takemasa Takii
- Department of Molecular Health Sciences, Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe, Mizuho-ku, Nagoya 467-8603
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Lemmer Y, Kalombo L, Pietersen RD, Jones AT, Semete-Makokotlela B, Van Wyngaardt S, Ramalapa B, Stoltz AC, Baker B, Verschoor JA, Swai HS, de Chastellier C. Mycolic acids, a promising mycobacterial ligand for targeting of nanoencapsulated drugs in tuberculosis. J Control Release 2015; 211:94-104. [PMID: 26055640 DOI: 10.1016/j.jconrel.2015.06.005] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Revised: 06/02/2015] [Accepted: 06/04/2015] [Indexed: 12/23/2022]
Abstract
The appearance of drug-resistant strains of Mycobacterium tuberculosis (Mtb) poses a great challenge to the development of novel treatment programmes to combat tuberculosis. Since innovative nanotechnologies might alleviate the limitations of current therapies, we have designed a new nanoformulation for use as an anti-TB drug delivery system. It consists of incorporating mycobacterial cell wall mycolic acids (MA) as targeting ligands into a drug-encapsulating Poly dl-lactic-co-glycolic acid polymer (PLGA), via a double emulsion solvent evaporation technique. Bone marrow-derived mouse macrophages, either uninfected or infected with different mycobacterial strains (Mycobacterium avium, Mycobacterium bovis BCG or Mtb), were exposed to encapsulated isoniazid-PLGA nanoparticles (NPs) using MA as a targeting ligand. The fate of the NPs was monitored by electron microscopy. Our study showed that i) the inclusion of MA in the nanoformulations resulted in their expression on the outer surface and a significant increase in phagocytic uptake of the NPs; ii) nanoparticle-containing phagosomes were rapidly processed into phagolysosomes, whether MA had been included or not; and iii) nanoparticle-containing phagolysosomes did not fuse with non-matured mycobacterium-containing phagosomes, but fusion events with mycobacterium-containing phagolysosomes were clearly observed.
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Affiliation(s)
- Yolandy Lemmer
- Polymers and Composites, Council for Scientific and Industrial Research, Pretoria, South Africa.
| | - Lonji Kalombo
- Polymers and Composites, Council for Scientific and Industrial Research, Pretoria, South Africa
| | - Ray-Dean Pietersen
- DST-CBTBR Department Molecular Biology and Human Genetics, Stellenbosch University, Cape Town, South Africa
| | - Arwyn T Jones
- Cardiff School of Pharmacy and Pharmaceutical Sciences, Cardiff University, Wales, UK
| | | | | | - Bathabile Ramalapa
- Polymers and Composites, Council for Scientific and Industrial Research, Pretoria, South Africa
| | - Anton C Stoltz
- Department of Infectious Diseases, University of Pretoria, Pretoria, South Africa
| | - Bienyameen Baker
- DST-CBTBR Department Molecular Biology and Human Genetics, Stellenbosch University, Cape Town, South Africa
| | - Jan A Verschoor
- Department of Biochemistry, University of Pretoria, Pretoria, South Africa
| | - Hulda S Swai
- Polymers and Composites, Council for Scientific and Industrial Research, Pretoria, South Africa
| | - Chantal de Chastellier
- Centre d'Immunologie de Marseille-Luminy (CIML), Aix Marseille University, UM 2, INSERM UMR 1104, CNRS UMR 7280, 163 avenue de Luminy, 13288 Marseille Cedex 09, France
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Groenewald W, Baird MS, Verschoor JA, Minnikin DE, Croft AK. Differential spontaneous folding of mycolic acids from Mycobacterium tuberculosis. Chem Phys Lipids 2014; 180:15-22. [DOI: 10.1016/j.chemphyslip.2013.12.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2013] [Revised: 12/06/2013] [Accepted: 12/09/2013] [Indexed: 10/25/2022]
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Purwantini E, Mukhopadhyay B. Rv0132c of Mycobacterium tuberculosis encodes a coenzyme F420-dependent hydroxymycolic acid dehydrogenase. PLoS One 2013; 8:e81985. [PMID: 24349169 PMCID: PMC3859598 DOI: 10.1371/journal.pone.0081985] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Accepted: 10/19/2013] [Indexed: 11/19/2022] Open
Abstract
The ability of Mycobacterium tuberculosis to manipulate and evade human immune system is in part due to its extraordinarily complex cell wall. One of the key components of this cell wall is a family of lipids called mycolic acids. Oxygenation of mycolic acids generating methoxy- and ketomycolic acids enhances the pathogenic attributes of M. tuberculosis. Thus, the respective enzymes are of interest in the research on mycobacteria. The generation of methoxy- and ketomycolic acids proceeds through intermediary formation of hydroxymycolic acids. While the methyl transferase that generates methoxymycolic acids from hydroxymycolic acids is known, hydroxymycolic acids dehydrogenase that oxidizes hydroxymycolic acids to ketomycolic acids has been elusive. We found that hydroxymycolic acid dehydrogenase is encoded by the rv0132c gene and the enzyme utilizes F420, a deazaflavin coenzyme, as electron carrier, and accordingly we called it F420-dependent hydroxymycolic acid dehydrogenase. This is the first report on the involvement of F420 in the synthesis of a mycobacterial cell envelope. Also, F420-dependent hydroxymycolic acid dehydrogenase was inhibited by PA-824, and therefore, it is a previously unknown target for this new tuberculosis drug.
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Affiliation(s)
- Endang Purwantini
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia, United States of America
- Virginia Bioinformatics Institute, Virginia Tech, Blacksburg, Virginia, United States of America
| | - Biswarup Mukhopadhyay
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia, United States of America
- Virginia Bioinformatics Institute, Virginia Tech, Blacksburg, Virginia, United States of America
- Departments of Biological Sciences, Virginia Tech, Blacksburg, Virginia, United States of America
- Virginia Tech Carilion School of Medicine, Virginia Tech, Blacksburg, Virginia, United States of America
- * E-mail:
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Evidence for a unique species-specific hypersensitive epitope in Mycobacterium tuberculosis derived cord factor. Tuberculosis (Edinb) 2013; 93 Suppl:S88-93. [DOI: 10.1016/s1472-9792(13)70017-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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20
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Rapid method for Mycobacterium tuberculosis identification using electrospray ionization tandem mass spectrometry analysis of mycolic acids. Diagn Microbiol Infect Dis 2013; 76:298-305. [DOI: 10.1016/j.diagmicrobio.2013.03.025] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2012] [Revised: 03/15/2013] [Accepted: 03/26/2013] [Indexed: 11/21/2022]
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21
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Chan CE, Zhao BZ, Cazenave-Gassiot A, Pang SW, Bendt AK, Wenk MR, MacAry PA, Hanson BJ. Novel phage display-derived mycolic acid-specific antibodies with potential for tuberculosis diagnosis. J Lipid Res 2013; 54:2924-32. [PMID: 23797850 DOI: 10.1194/jlr.d036137] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Tuberculosis is a major cause of mortality and morbidity due to infectious disease. However, current clinical diagnostic methodologies such as PCR, sputum culture, or smear microscopy are not ideal. Antibody-based assays are a suitable alternative but require specific antibodies against a suitable biomarker. Mycolic acid, which has been found in patient sputum samples and comprises a large portion of the mycobacterial cell wall, is an ideal target. However, generating anti-lipid antibodies using traditional hybridoma methodologies is challenging and has limited the exploitation of this lipid as a diagnostic marker. We describe here the isolation and characterization of four anti-mycolic acid antibodies from a nonimmune antibody phage display library that can detect mycolic acids down to a limit of 4.5ng. All antibodies were specific for the methoxy subclass of mycolic acid with weak binding for α mycolic acid and did not show any binding to closely related lipids or other Mycobacterium tuberculosis (Mtb) derived lipids. We also determined the clinical utility of these antibodies based on their limit of detection for mycobacteria colony forming units (CFU). In combination with an optimized alkaline hydrolysis method for rapid lipid extraction, these antibodies can detect 10(5) CFU of Mycobacterium bovis BCG, a close relative of Mtb and therefore represent a novel approach for the development of diagnostic assays for lipid biomarkers.
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Affiliation(s)
- Conrad E Chan
- Department of Microbiology, National University of Singapore, Singapore, 117545 Singapore
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Verschoor JA, Baird MS, Grooten J. Towards understanding the functional diversity of cell wall mycolic acids of Mycobacterium tuberculosis. Prog Lipid Res 2012; 51:325-39. [PMID: 22659327 DOI: 10.1016/j.plipres.2012.05.002] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2011] [Revised: 03/05/2012] [Accepted: 05/23/2012] [Indexed: 01/08/2023]
Abstract
Mycolic acids constitute the waxy layer of the outer cell wall of Mycobacterium spp. and a few other genera. They are diverse in structure, providing a unique chromatographic foot-print for almost each of the more than 70 Mycobacterium species. Although mainly esterified to cell wall arabinogalactan, trehalose or glucose, some free mycolic acid is secreted during in vitro growth of Mycobacterium tuberculosis. In M. tuberculosis, α-, keto- and methoxy-mycolic acids are the main classes, each differing in their ability to attract neutrophils, induce foamy macrophages or adopt an antigenic structure for antibody recognition. Of interest is their particular relationship to cholesterol, discovered by their ability to attract cholesterol, to bind Amphotericin B or to be recognised by monoclonal antibodies that cross-react with cholesterol. The structural elements that determine this diverse functionality include the carboxylic acid in the mycolic motif, as well as the nature and stereochemistry of the two functional groups in the merochain. The functional diversity of mycolic acid classes implies that much information may be contained in the selective expression and secretion of mycolic acids to establish tuberculosis after infection of the host. Their cholesteroid nature may relate to how they utilize host cholesterol for their persistent survival.
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Affiliation(s)
- Jan A Verschoor
- Department Biochemistry, University of Pretoria, Pretoria 0002, South Africa.
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Khan AA, Chee SH, Stocker BL, Timmer MSM. The Synthesis of Long-Chain α-Alkyl-β-Hydroxy Esters Using Allylic Halides in a Fráter-Seebach Alkylation. European J Org Chem 2011. [DOI: 10.1002/ejoc.201101472] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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