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Petitpoisson L, Pichette A, Alsarraf J. Towards better syntheses of partially methylated carbohydrates? Org Chem Front 2022. [DOI: 10.1039/d2qo00893a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We give an overview of the reported synthetic strategies towards partially methylated glycosides and discuss how better protocols could stem from catalytic site-selective transformations of carbohydrates and cleaner methylation reagents.
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Affiliation(s)
- Lucas Petitpoisson
- Centre de recherche sur la boréalie (CREB), Laboratoire d'analyse et de séparation des essences végétales (LASEVE), Université du Québec à Chicoutimi, 555 boulevard de l'Université, Chicoutimi G7H 2B1, Québec, Canada
| | - André Pichette
- Centre de recherche sur la boréalie (CREB), Laboratoire d'analyse et de séparation des essences végétales (LASEVE), Université du Québec à Chicoutimi, 555 boulevard de l'Université, Chicoutimi G7H 2B1, Québec, Canada
| | - Jérôme Alsarraf
- Centre de recherche sur la boréalie (CREB), Laboratoire d'analyse et de séparation des essences végétales (LASEVE), Université du Québec à Chicoutimi, 555 boulevard de l'Université, Chicoutimi G7H 2B1, Québec, Canada
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Biosynthesis of mycobacterial methylmannose polysaccharides requires a unique 1- O-methyltransferase specific for 3- O-methylated mannosides. Proc Natl Acad Sci U S A 2019; 116:835-844. [PMID: 30606802 DOI: 10.1073/pnas.1813450116] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Mycobacteria are a wide group of organisms that includes strict pathogens, such as Mycobacterium tuberculosis, as well as environmental species known as nontuberculous mycobacteria (NTM), some of which-namely Mycobacterium avium-are important opportunistic pathogens. In addition to a distinctive cell envelope mediating critical interactions with the host immune system and largely responsible for their formidable resistance to antimicrobials, mycobacteria synthesize rare intracellular polymethylated polysaccharides implicated in the modulation of fatty acid metabolism, thus critical players in cell envelope assembly. These are the 6-O-methylglucose lipopolysaccharides (MGLP) ubiquitously detected across the Mycobacterium genus, and the 3-O-methylmannose polysaccharides (MMP) identified only in NTM. The polymethylated nature of these polysaccharides renders the intervening methyltransferases essential for their optimal function. Although the knowledge of MGLP biogenesis is greater than that of MMP biosynthesis, the methyltransferases of both pathways remain uncharacterized. Here, we report the identification and characterization of a unique S-adenosyl-l-methionine-dependent sugar 1-O-methyltransferase (MeT1) from Mycobacterium hassiacum that specifically blocks the 1-OH position of 3,3'-di-O-methyl-4α-mannobiose, a probable early precursor of MMP, which we chemically synthesized. The high-resolution 3D structure of MeT1 in complex with its exhausted cofactor, S-adenosyl-l-homocysteine, together with mutagenesis studies and molecular docking simulations, unveiled the enzyme's reaction mechanism. The functional and structural properties of this unique sugar methyltransferase further our knowledge of MMP biosynthesis and provide important tools to dissect the role of MMP in NTM physiology and resilience.
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Liu L, Siuda I, Richards MR, Renaud J, Kitova EN, Mayer PM, Tieleman DP, Lowary TL, Klassen JS. Structure and Stability of Carbohydrate-Lipid Interactions. Methylmannose Polysaccharide-Fatty Acid Complexes. Chembiochem 2016; 17:1571-8. [PMID: 27253157 DOI: 10.1002/cbic.201600123] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Indexed: 11/07/2022]
Abstract
We report a detailed study of the structure and stability of carbohydrate-lipid interactions. Complexes of a methylmannose polysaccharide (MMP) derivative and fatty acids (FAs) served as model systems. The dependence of solution affinities and gas-phase dissociation activation energies (Ea ) on FA length indicates a dominant role of carbohydrate-lipid interactions in stabilizing (MMP+FA) complexes. Solution (1) H NMR results reveal weak interactions between MMP methyl groups and FA acyl chain; MD simulations suggest the complexes are disordered. The contribution of FA methylene groups to the Ea is similar to that of heats of transfer of n-alkanes from the gas phase to polar solvents, thus suggesting that MMP binds lipids through dipole-induced dipole interactions. The MD results point to hydrophobic interactions and H-bonds with the FA carboxyl group. Comparison of collision cross sections of deprotonated (MMP+FA) ions with MD structures suggests that the gaseous complexes are disordered.
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Affiliation(s)
- Lan Liu
- Alberta Glycomics Centre, Department of Chemistry, University of Alberta, Edmonton, Alberta, T6G 2G2, Canada
| | - Iwona Siuda
- Centre for Molecular Simulation, Department of Biological Sciences, University of Calgary, Calgary, Alberta, T2N 1N4, Canada
| | - Michele R Richards
- Alberta Glycomics Centre, Department of Chemistry, University of Alberta, Edmonton, Alberta, T6G 2G2, Canada
| | - Justin Renaud
- Chemistry Department, University of Ottawa, Ottawa, Ontario, K1N 6N5, Canada
| | - Elena N Kitova
- Alberta Glycomics Centre, Department of Chemistry, University of Alberta, Edmonton, Alberta, T6G 2G2, Canada
| | - Paul M Mayer
- Chemistry Department, University of Ottawa, Ottawa, Ontario, K1N 6N5, Canada
| | - D Peter Tieleman
- Centre for Molecular Simulation, Department of Biological Sciences, University of Calgary, Calgary, Alberta, T2N 1N4, Canada
| | - Todd L Lowary
- Alberta Glycomics Centre, Department of Chemistry, University of Alberta, Edmonton, Alberta, T6G 2G2, Canada
| | - John S Klassen
- Alberta Glycomics Centre, Department of Chemistry, University of Alberta, Edmonton, Alberta, T6G 2G2, Canada.
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