1
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Poškaitė G, Wheatley DE, Wells N, Linclau B, Sinnaeve D. Obtaining Pure 1H NMR Spectra of Individual Pyranose and Furanose Anomers of Reducing Deoxyfluorinated Sugars. J Org Chem 2023; 88:13908-13925. [PMID: 37754916 PMCID: PMC10563139 DOI: 10.1021/acs.joc.3c01503] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Indexed: 09/28/2023]
Abstract
Due to tautomeric equilibria, NMR spectra of reducing sugars can be complex with many overlapping resonances. This hampers coupling constant determination, which is required for conformational analysis and configurational assignment of substituents. Given that mixtures of interconverting species are physically inseparable, easy-to-use techniques that enable facile full 1H NMR characterization of sugars are of interest. Here, we show that individual spectra of both pyranoside and furanoside forms of reducing fluorosugars can be obtained using 1D FESTA. We discuss the unique opportunities offered by FESTA over standard sel-TOCSY and show how it allows a more complete characterization. We illustrate the power of FESTA by presenting the first full NMR characterization of many fluorosugars, including of the important fluorosugar 2-deoxy-2-fluoroglucose. We discuss in detail all practical considerations for setting up FESTA experiments for fluorosugars, which can be extended to any mixture of fluorine-containing species interconverting slowly on the NMR frequency-time scale.
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Affiliation(s)
- Gabija Poškaitė
- School
of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, United Kingdom
| | - David E. Wheatley
- School
of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, United Kingdom
| | - Neil Wells
- School
of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, United Kingdom
| | - Bruno Linclau
- School
of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, United Kingdom
- Department
of Organic and Macromolecular Chemistry, Ghent University, Campus
Sterre, Krijgslaan 281-S4, Ghent 9000, Belgium
| | - Davy Sinnaeve
- Univ. Lille, Inserm, CHU Lille, Institut Pasteur de Lille, U1167 RID-AGE - Risk Factors and Molecular Determinants of Aging-Related Diseases, F-59000 Lille, France
- CNRS, EMR9002 Integrative Structural Biology, F-59000 Lille, France
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2
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Council CE, Kilpin KJ, Gusthart JS, Allman SA, Linclau B, Lee SS. Enzymatic glycosylation involving fluorinated carbohydrates. Org Biomol Chem 2021; 18:3423-3451. [PMID: 32319497 DOI: 10.1039/d0ob00436g] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Fluorinated carbohydrates, where one (or more) fluorine atom(s) have been introduced into a carbohydrate structure, typically through deoxyfluorination chemistry, have a wide range of applications in the glycosciences. Fluorinated derivatives of galactose, glucose, N-acetylgalactosamine, N-acetylglucosamine, talose, fucose and sialic acid have been employed as either donor or acceptor substrates in glycosylation reactions. Fluorinated donors can be synthesised by synthetic methods or produced enzymatically from chemically fluorinated sugars. The latter process is mediated by enzymes such as kinases, phosphorylases and nucleotidyltransferases. Fluorinated donors produced by either method can subsequently be used in glycosylation reactions mediated by glycosyltransferases, or phosphorylases yielding fluorinated oligosaccharide or glycoconjugate products. Fluorinated acceptor substrates are typically synthesised chemically. Glycosyltransferases are most commonly used in conjunction with natural donors to further elaborate fluorinated acceptor substrates. Glycoside hydrolases are used with either fluorinated donors or acceptors. The activity of enzymes towards fluorinated sugars is often lower than towards the natural sugar substrates irrespective of donor or acceptor. This may be in part attributed to elimination of the contribution of the hydroxyl group to the binding of the substrate to enzymes. However, in many cases, enzymes still maintain a significant activity, and reactions may be optimised where necessary, enabling enzymes to be used more successfully in the production of fluorinated carbohydrates. This review describes the current state of the art regarding chemoenzymatic production of fluorinated carbohydrates, focusing specifically on examples of the enzymatic production of activated fluorinated donors and enzymatic glycosylation involving fluorinated sugars as either glycosyl donors or acceptors.
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Affiliation(s)
- Claire E Council
- School of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, UK.
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3
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Linclau B, Ardá A, Reichardt NC, Sollogoub M, Unione L, Vincent SP, Jiménez-Barbero J. Fluorinated carbohydrates as chemical probes for molecular recognition studies. Current status and perspectives. Chem Soc Rev 2021; 49:3863-3888. [PMID: 32520059 DOI: 10.1039/c9cs00099b] [Citation(s) in RCA: 63] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
This review provides an extensive summary of the effects of carbohydrate fluorination with regard to changes in physical, chemical and biological properties with respect to regular saccharides. The specific structural, conformational, stability, reactivity and interaction features of fluorinated sugars are described, as well as their applications as probes and in chemical biology.
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Affiliation(s)
- Bruno Linclau
- School of Chemistry, University of Southampton, Highfield, Southampton SO171BJ, UK
| | - Ana Ardá
- CIC bioGUNE, Basque Research and Technology Alliance (BRTA), 48160 Derio, Spain.
| | | | - Matthieu Sollogoub
- Sorbonne Université, CNRS, Institut Parisien de Chimie Moléculaire, UMR 8232, 4 place Jussieu, 75005 Paris, France
| | - Luca Unione
- Department of Chemical Biology and Drug Discovery, Utrecht Institute for Pharmaceutical Science, Utrecht University, Universiteitsweg 99, 3584 CG, Utrecht, The Netherlands
| | - Stéphane P Vincent
- Department of Chemistry, Laboratory of Bio-organic Chemistry, University of Namur (UNamur), B-5000 Namur, Belgium
| | - Jesús Jiménez-Barbero
- CIC bioGUNE, Basque Research and Technology Alliance (BRTA), 48160 Derio, Spain. and Ikerbasque, Basque Foundation for Science, Maria Diaz de Haro 3, 48013 Bilbao, Spain and Department of Organic Chemistry II, Faculty of Science and Technology, UPV/EHU, 48940 Leioa, Spain
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4
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Hevey R. The Role of Fluorine in Glycomimetic Drug Design. Chemistry 2020; 27:2240-2253. [DOI: 10.1002/chem.202003135] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Indexed: 11/10/2022]
Affiliation(s)
- Rachel Hevey
- Department of Pharmaceutical Sciences University of Basel, Pharmazentrum Klingelbergstrasse 50 4056 Basel Switzerland
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5
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Vaugenot J, El Harras A, Tasseau O, Marchal R, Legentil L, Le Guennic B, Benvegnu T, Ferrières V. 6-Deoxy-6-fluoro galactofuranosides: regioselective glycosylation, unexpected reactivity, and anti-leishmanial activity. Org Biomol Chem 2020; 18:1462-1475. [PMID: 32025679 DOI: 10.1039/c9ob02596k] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Selective glycosylation of the C-6 fluorinated galactofuranosyl acceptor 2 was studied with four galactofuranosyl donors. It was highlighted that this electron-withdrawing atom strongly impacted the behavior of the acceptor, thus leading to unprecedented glycosylation pathways. Competition between expected glycosylation of 2, ring expansion of this acceptor and furanosylation, and intermolecular aglycon transfer was observed. Further investigation of the fluorinated synthetic compounds showed that the presence of fluorine atom contributed to increase the inhibition of the growth of Leishmania tarentolae, a non-pathogenic strain of Leishmania.
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Affiliation(s)
- Jeane Vaugenot
- Univ Rennes, Ecole Nationale Supérieure de Chimie de Rennes, CNRS, ISCR-UMR 6226, F-35000 Rennes, France.
| | - Abderrafek El Harras
- Univ Rennes, Ecole Nationale Supérieure de Chimie de Rennes, CNRS, ISCR-UMR 6226, F-35000 Rennes, France.
| | - Olivier Tasseau
- Univ Rennes, Ecole Nationale Supérieure de Chimie de Rennes, CNRS, ISCR-UMR 6226, F-35000 Rennes, France.
| | - Rémi Marchal
- Univ Rennes, Ecole Nationale Supérieure de Chimie de Rennes, CNRS, ISCR-UMR 6226, F-35000 Rennes, France.
| | - Laurent Legentil
- Univ Rennes, Ecole Nationale Supérieure de Chimie de Rennes, CNRS, ISCR-UMR 6226, F-35000 Rennes, France.
| | - Boris Le Guennic
- Univ Rennes, Ecole Nationale Supérieure de Chimie de Rennes, CNRS, ISCR-UMR 6226, F-35000 Rennes, France.
| | - Thierry Benvegnu
- Univ Rennes, Ecole Nationale Supérieure de Chimie de Rennes, CNRS, ISCR-UMR 6226, F-35000 Rennes, France.
| | - Vincent Ferrières
- Univ Rennes, Ecole Nationale Supérieure de Chimie de Rennes, CNRS, ISCR-UMR 6226, F-35000 Rennes, France.
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6
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Kerins L, Byrne S, Gabba A, Murphy PV. Anomer Preferences for Glucuronic and Galacturonic Acid and Derivatives and Influence of Electron-Withdrawing Substituents. J Org Chem 2018; 83:7714-7729. [DOI: 10.1021/acs.joc.8b00610] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Louise Kerins
- School of Chemistry, National University of Ireland Galway, University Road, Galway, Ireland
| | - Sylvester Byrne
- School of Chemistry, National University of Ireland Galway, University Road, Galway, Ireland
| | - Adele Gabba
- School of Chemistry, National University of Ireland Galway, University Road, Galway, Ireland
| | - Paul V. Murphy
- School of Chemistry, National University of Ireland Galway, University Road, Galway, Ireland
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Wetterhorn KM, Newmister SA, Caniza RK, Busman M, McCormick SP, Berthiller F, Adam G, Rayment I. Crystal Structure of Os79 (Os04g0206600) from Oryza sativa: A UDP-glucosyltransferase Involved in the Detoxification of Deoxynivalenol. Biochemistry 2016; 55:6175-6186. [DOI: 10.1021/acs.biochem.6b00709] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Karl M. Wetterhorn
- Department
of Biochemistry, University of Wisconsin—Madison, Madison, Wisconsin 53706, United States
| | - Sean A. Newmister
- Department
of Biochemistry, University of Wisconsin—Madison, Madison, Wisconsin 53706, United States
| | - Rachell K. Caniza
- Department
of Biochemistry, University of Wisconsin—Madison, Madison, Wisconsin 53706, United States
| | - Mark Busman
- Mycotoxin
Prevention and Applied Microbiology Research Unit, USDA/ARS, National Center for Agricultural Utilization Research, Peoria, Illinois 61604, United States
| | - Susan P. McCormick
- Mycotoxin
Prevention and Applied Microbiology Research Unit, USDA/ARS, National Center for Agricultural Utilization Research, Peoria, Illinois 61604, United States
| | - Franz Berthiller
- Christian
Doppler Laboratory for Mycotoxin Metabolism, Center for Analytical
Chemistry, Department of Agrobiotechnology (IFA-Tulln), University of Natural Resources and Life Sciences, Vienna (BOKU), Konrad-Lorenz-Strasse
20, 3430 Tulln, Austria
| | - Gerhard Adam
- Department
of Applied Genetics and Cell Biology, University of Natural Resources and Life Sciences, Vienna (BOKU), Konrad-Lorenz-Strasse 24, 3430 Tulln, Austria
| | - Ivan Rayment
- Department
of Biochemistry, University of Wisconsin—Madison, Madison, Wisconsin 53706, United States
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8
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Eppe G, El Bkassiny S, Vincent SP. Galactofuranose Biosynthesis: Discovery, Mechanisms and Therapeutic Relevance. CARBOHYDRATES IN DRUG DESIGN AND DISCOVERY 2015. [DOI: 10.1039/9781849739993-00209] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Galactofuranose, the atypical and thermodynamically disfavored form of d-galactose, has in reality a very old history in chemistry and biochemistry. The purpose of this book chapter is to give an overview on the fundamental aspects of the galactofuranose biosynthesis, from the biological occurrence to the search of inhibitors.
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Affiliation(s)
- Guillaume Eppe
- University of Namur, Département de Chimie, Laboratoire de Chimie Bio-Organique rue de Bruxelles 61 B-5000 Namur Belgium
| | - Sandy El Bkassiny
- University of Namur, Département de Chimie, Laboratoire de Chimie Bio-Organique rue de Bruxelles 61 B-5000 Namur Belgium
| | - Stéphane P. Vincent
- University of Namur, Département de Chimie, Laboratoire de Chimie Bio-Organique rue de Bruxelles 61 B-5000 Namur Belgium
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9
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van Straaten KE, Kuttiyatveetil JRA, Sevrain CM, Villaume SA, Jiménez-Barbero J, Linclau B, Vincent SP, Sanders DAR. Structural basis of ligand binding to UDP-galactopyranose mutase from Mycobacterium tuberculosis using substrate and tetrafluorinated substrate analogues. J Am Chem Soc 2015; 137:1230-44. [PMID: 25562380 DOI: 10.1021/ja511204p] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
UDP-Galactopyranose mutase (UGM) is a flavin-containing enzyme that catalyzes the reversible conversion of UDP-galactopyranose (UDP-Galp) to UDP-galactofuranose (UDP-Galf) and plays a key role in the biosynthesis of the mycobacterial cell wall galactofuran. A soluble, active form of UGM from Mycobacterium tuberculosis (MtUGM) was obtained from a dual His6-MBP-tagged MtUGM construct. We present the first complex structures of MtUGM with bound substrate UDP-Galp (both oxidized flavin and reduced flavin). In addition, we have determined the complex structures of MtUGM with inhibitors (UDP and the dideoxy-tetrafluorinated analogues of both UDP-Galp (UDP-F4-Galp) and UDP-Galf (UDP-F4-Galf)), which represent the first complex structures of UGM with an analogue in the furanose form, as well as the first structures of dideoxy-tetrafluorinated sugar analogues bound to a protein. These structures provide detailed insight into ligand recognition by MtUGM and show an overall binding mode similar to those reported for other prokaryotic UGMs. The binding of the ligand induces conformational changes in the enzyme, allowing ligand binding and active-site closure. In addition, the complex structure of MtUGM with UDP-F4-Galf reveals the first detailed insight into how the furanose moiety binds to UGM. In particular, this study confirmed that the furanoside adopts a high-energy conformation ((4)E) within the catalytic pocket. Moreover, these investigations provide structural insights into the enhanced binding of the dideoxy-tetrafluorinated sugars compared to unmodified analogues. These results will help in the design of carbohydrate mimetics and drug development, and show the enormous possibilities for the use of polyfluorination in the design of carbohydrate mimetics.
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Affiliation(s)
- Karin E van Straaten
- Department of Chemistry, University of Saskatchewan , 110 Science Place, Saskatoon S7N 5C9, Canada
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10
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Tanner JJ, Boechi L, Andrew McCammon J, Sobrado P. Structure, mechanism, and dynamics of UDP-galactopyranose mutase. Arch Biochem Biophys 2014; 544:128-41. [PMID: 24096172 PMCID: PMC3946560 DOI: 10.1016/j.abb.2013.09.017] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2013] [Revised: 09/25/2013] [Accepted: 09/26/2013] [Indexed: 11/16/2022]
Abstract
The flavoenzyme UDP-galactopyranose mutase (UGM) is a key enzyme in galactofuranose biosynthesis. The enzyme catalyzes the 6-to-5 ring contraction of UDP-galactopyranose to UDP-galactofuranose. Galactofuranose is absent in humans yet is an essential component of bacterial and fungal cell walls and a cell surface virulence factor in protozoan parasites. Thus, inhibition of galactofuranose biosynthesis is a valid strategy for developing new antimicrobials. UGM is an excellent target in this effort because the product of the UGM reaction represents the first appearance of galactofuranose in the biosynthetic pathway. The UGM reaction is redox neutral, which is atypical for flavoenzymes, motivating intense examination of the chemical mechanism and structural features that tune the flavin for its unique role in catalysis. These studies show that the flavin functions as nucleophile, forming a flavin-sugar adduct that facilitates galactose-ring opening and contraction. The 3-dimensional fold is novel and conserved among all UGMs, however the larger eukaryotic enzymes have additional secondary structure elements that lead to significant differences in quaternary structure, substrate conformation, and conformational flexibility. Here we present a comprehensive review of UGM three-dimensional structure, provide an update on recent developments in understanding the mechanism of the enzyme, and summarize computational studies of active site flexibility.
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Affiliation(s)
- John J Tanner
- Departments of Chemistry and Biochemistry, University of Missouri, Columbia, MO, United States.
| | - Leonardo Boechi
- Departments of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA, United States
| | - J Andrew McCammon
- Departments of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA, United States; Howard Hughes Medical Institute, Department of Pharmacology, University of California San Diego, La Jolla, CA, United States
| | - Pablo Sobrado
- Department of Biochemistry, Virginia Tech, Blacksburg, VA, United States; Virginia Tech Center for Drug Discovery, Virginia Tech, Blacksburg, VA, United States.
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11
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N'Go I, Golten S, Ardá A, Cañada J, Jiménez-Barbero J, Linclau B, Vincent SP. Tetrafluorination of sugars as strategy for enhancing protein-carbohydrate affinity: application to UDP-Galp mutase inhibition. Chemistry 2013; 20:106-12. [PMID: 24311368 DOI: 10.1002/chem.201303693] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Indexed: 01/16/2023]
Abstract
Tetrafluorinated analogues of both UDP-galactopyranose and UDP-galactofuranose have been synthesized and assayed against UDP-galactopyranose mutase, a key enzyme for Mycobacterium tuberculosis cell wall biosynthesis. Competition assays and STD-NMR spectroscopy techniques have evidenced not only the first unambiguous case of affinity enhancement through local sugar polyfluorination, but also showed that tetrafluorination can still have a beneficial effect on binding when monofluorination at the same position does not.
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Affiliation(s)
- Inès N'Go
- Department of Chemistry, University of Namur, Rue de Bruxelles 61, 5000 Namur (Belgium)
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12
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Huang W, Gauld JW. Tautomerization in the UDP-galactopyranose mutase mechanism: a DFT-cluster and QM/MM investigation. J Phys Chem B 2012; 116:14040-50. [PMID: 23148701 DOI: 10.1021/jp310952c] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
UDP-galactopyranose mutase (UGM) is a key flavoenzyme involved in cell wall biosynthesis of a variety of pathogenic bacteria and hence, integral to their survival. It catalyzes the interconversion of UDP-galactopyranose (UDP-Galp) and UDP-galactofuranose (UDP-Galf); interconversion of the galactose moieties six- and five-membered ring forms. We have synergistically applied both density functional theory (DFT)-cluster and ONIOM quantum mechanics/molecular mechanics (QM/MM) hybrid calculations to elucidate the mechanism of this important enzyme and to provide insight into its uncommon mechanism. It is shown that the flavin must initially be in its fully reduced form. Furthermore, it requires an N5(FAD)-H proton, which, through a series of tautomerizations, is transferred onto the ring oxygen of the substrate's Galp moiety to facilitate ring-opening with concomitant Schiff base formation. Conversely, Galf formation is achieved via a series of tautomerizations involving proton transfer from the galactose's -O4(Gal)H group ultimately onto the flavin's N5(FAD) center. With the DFT-cluster model, the overall rate-limiting step with a barrier of 120.0 kJ mol(-1) is the interconversion of two Galf-flavin tautomers: one containing a C4(FAD)-OH group and the other a tetrahedral protonated-N5(FAD) center. In contrast, in the QM/MM model a considerably more extensive chemical model was used that included all of the residues surrounding the active site, and modeled both their steric and electrostatic effects. In this approach, the overall rate-limiting step with a barrier of 99.2 kJ mol(-1) occurs during conformational rearrangement of the Schiff base linear galactose-flavin complex. This appears due to the lack of suitable functional groups to facilitate the rearrangement.
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Affiliation(s)
- WenJuan Huang
- Department of Chemistry and Biochemistry, University of Windsor, Ontario, Canada
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13
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Abstract
Enzymes containing flavin cofactors are predominantly involved in redox reactions in numerous cellular processes where the protein environment modulates the chemical reactivity of the flavin to either transfer one or two electrons. Some flavoenzymes catalyze reactions with no net redox change. In these reactions, the protein environment modulates the reactivity of the flavin to perform novel chemistries. Recent mechanistic and structural data supporting novel flavin functionalities in reactions catalyzed by chorismate synthase, type II isopentenyl diphosphate isomerase, UDP-galactopyranose mutase, and alkyl-dihydroxyacetonephosphate synthase are presented in this review. In these enzymes, the flavin plays either a direct role in acid/base reactions or as a nucleophile or electrophile. In addition, the flavin cofactor is proposed to function as a "molecular scaffold" in the formation of UDP-galactofuranose and alkyl-dihydroxyacetonephosphate by forming a covalent adduct with reaction intermediates.
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Affiliation(s)
- Pablo Sobrado
- Department of Biochemistry, Virginia Tech, Blacksburg, VA 24061, USA.
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14
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Ansiaux C, N'Go I, Vincent SP. Reversible and Efficient Inhibition of UDP-Galactopyranose Mutase by Electrophilic, Constrained and Unsaturated UDP-Galactitol Analogues. Chemistry 2012; 18:14860-6. [DOI: 10.1002/chem.201202302] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Indexed: 11/09/2022]
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15
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Durantie E, Bucher C, Gilmour R. Fluorine-directed β-galactosylation: chemical glycosylation development by molecular editing. Chemistry 2012; 18:8208-15. [PMID: 22592962 DOI: 10.1002/chem.201200468] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2012] [Indexed: 11/10/2022]
Abstract
Validation of the 2-fluoro substituent as an inert steering group to control chemical glycosylation is presented. A molecular editing study has revealed that the exceptional levels of diastereocontrol in glycosylation processes by using 2-fluoro-3,4,6-tri-O-benzyl glucopyranosyl trichloroacetimidate (TCA) scaffolds are a consequence of the 2R,3S,4S stereotriad. This study has also revealed that epimerization at C4, results in a substantial enhancement in β-selectivity (up to β/α 300:1).
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Affiliation(s)
- Estelle Durantie
- Laboratory for Organic Chemistry, Swiss Federal Institute of Technology (ETH) Zürich, 8093 Zürich, Switzerland
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16
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Chlubnova I, Legentil L, Dureau R, Pennec A, Almendros M, Daniellou R, Nugier-Chauvin C, Ferrières V. Specific and non-specific enzymes for furanosyl-containing conjugates: biosynthesis, metabolism, and chemo-enzymatic synthesis. Carbohydr Res 2012; 356:44-61. [PMID: 22554502 DOI: 10.1016/j.carres.2012.04.002] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2012] [Revised: 04/02/2012] [Accepted: 04/03/2012] [Indexed: 11/27/2022]
Abstract
There is no doubt now that the synthesis of compounds of varying complexity such as saccharides and derivatives thereof continuously grows with enzymatic methods. This review focuses on recent basic knowledge on enzymes specifically involved in the biosynthesis and degradation of furanosyl-containing polysaccharides and conjugates. Moreover, and when possible, biocatalyzed approaches, alternative to standard synthesis, will be detailed in order to strengthen the high potential of these biocatalysts to go further with the preparation of rare furanosides. Interesting results will be also proposed with chemo-enzymatic processes based on nonfuranosyl-specific enzymes.
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Affiliation(s)
- Ilona Chlubnova
- Ecole Nationale Supérieure de Chimie de Rennes, CNRS, UMR 6226, Avenue du Général Leclerc, CS 50837, 35708 Rennes Cedex 7, France
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17
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Peltier P, Beláňová M, Dianišková P, Zhou R, Zheng RB, Pearcey JA, Joe M, Brennan PJ, Nugier-Chauvin C, Ferrières V, Lowary TL, Daniellou R, Mikušová K. Synthetic UDP-furanoses as potent inhibitors of mycobacterial galactan biogenesis. ACTA ACUST UNITED AC 2011; 17:1356-66. [PMID: 21168771 DOI: 10.1016/j.chembiol.2010.10.014] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2010] [Revised: 10/25/2010] [Accepted: 10/27/2010] [Indexed: 11/29/2022]
Abstract
UDP-galactofuranose (UDP-Galf) is a substrate for two types of enzymes, UDP-galactopyranose mutase and galactofuranosyltransferases, which are present in many pathogenic organisms but absent from mammals. In particular, these enzymes are involved in the biosynthesis of cell wall galactan, a polymer essential for the survival of the causative agent of tuberculosis, Mycobacterium tuberculosis. We describe here the synthesis of derivatives of UDP-Galf modified at C-5 and C-6 using a chemoenzymatic route. In cell-free assays, these compounds prevented the formation of mycobacterial galactan, via the production of short "dead-end" intermediates resulting from their incorporation into the growing oligosaccharide chain. Modified UDP-furanoses thus constitute novel probes for the study of the two classes of enzymes involved in mycobacterial galactan assembly, and studies with these compounds may ultimately facilitate the future development of new therapeutic agents against tuberculosis.
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Affiliation(s)
- Pauline Peltier
- Ecole Nationale Supérieure de Chimie de Rennes, CNRS, UMR 6226, 35708 Rennes, Cedex 7, France
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18
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Ioannou A, Cini E, Timofte RS, Flitsch SL, Turner NJ, Linclau B. Heavily fluorinated carbohydrates as enzyme substrates: oxidation of tetrafluorinated galactose by galactose oxidase. Chem Commun (Camb) 2011; 47:11228-30. [DOI: 10.1039/c1cc13956h] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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19
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Sadeghi-Khomami A, Forcada TJ, Wilson C, Sanders DAR, Thomas NR. The UDP-Galp mutase catalyzed isomerization: synthesis and evaluation of 1,4-anhydro-beta-D-galactopyranose and its [2.2.2] methylene homologue. Org Biomol Chem 2010; 8:1596-602. [PMID: 20237670 DOI: 10.1039/b917409e] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The synthesis of 1,4-anhydro-beta-D-galactopyranose (1,5-anhydro-alpha-D-galactofuranose), a proposed intermediate in the ring contraction isomerisation catalyzed by UDP-galactopyranose mutase, together with its [2.2.2] bicyclic methylene homologue, synthesised as a possible competitive inhibitor or alternative substrate, are reported. Neither compound was found to be an inhibitor or substrate for UDP-galactopyranose mutase from Klebsiella pneumoniae.
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Affiliation(s)
- Ali Sadeghi-Khomami
- School of Chemistry, Centre for Biomolecular Sciences, University of Nottingham, University Park, Nottingham, United Kingdom NG7 2RD
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20
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Richards MR, Lowary TL. Chemistry and biology of galactofuranose-containing polysaccharides. Chembiochem 2009; 10:1920-38. [PMID: 19591187 DOI: 10.1002/cbic.200900208] [Citation(s) in RCA: 170] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The thermodynamically less stable form of galactose-galactofuranose (Galf)-is essential for the viability of several pathogenic species of bacteria and protozoa but absent in this form in mammals, so the biochemical pathways by which Galf-containing glycans are assembled and catabolysed are attractive sites for drug action. This potential has led to increasing interest in the synthesis of molecules containing Galf residues, their subsequent use in studies directed towards understanding the enzymes that process these residues and the identification of potential inhibitors of these pathways. Major achievements of the past several years have included an in-depth understanding of the mechanism of UDP-galactopyranose mutase (UGM), the enzyme that produces UDP-Galf, which is the donor species for galactofuranosyltransferases. A number of methods for the synthesis of galactofuranosides have also been developed, and practitioners in the field now have many options for the initiation of a synthesis of glycoconjugates containing either alpha- or beta-Galf residues. UDP-Galf has also been prepared by a number of approaches, and it appears that a chemoenzymatic approach is currently the most viable method for producing multi-milligram amounts of this important intermediate. Recent advances both in the understanding of the mechanism of UGM and in the synthesis of galactofuranose and its derivatives are highlighted in this review.
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Affiliation(s)
- Michele R Richards
- Alberta Ingenuity Centre for Carbohydrate Science and Department of Chemistry, University of Alberta, Gunning-Lemieux Chemistry Centre, Edmonton, AB T6G 2G2 (Canada)
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21
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Horler RSP, Müller A, Williamson DC, Potts JR, Wilson KS, Thomas GH. Furanose-specific sugar transport: characterization of a bacterial galactofuranose-binding protein. J Biol Chem 2009; 284:31156-63. [PMID: 19744923 PMCID: PMC2781514 DOI: 10.1074/jbc.m109.054296] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2009] [Revised: 09/06/2009] [Indexed: 12/31/2022] Open
Abstract
The widespread utilization of sugars by microbes is reflected in the diversity and multiplicity of cellular transporters used to acquire these compounds from the environment. The model bacterium Escherichia coli has numerous transporters that allow it to take up hexoses and pentoses, which recognize the more abundant pyranose forms of these sugars. Here we report the biochemical and structural characterization of a transporter protein YtfQ from E. coli that forms part of an uncharacterized ABC transporter system. Remarkably the crystal structure of this protein, solved to 1.2 A using x-ray crystallography, revealed that YtfQ binds a single molecule of galactofuranose in its ligand binding pocket. Selective binding of galactofuranose over galactopyranose was also observed using NMR methods that determined the form of the sugar released from the protein. The pattern of expression of the ytfQRTyjfF operon encoding this transporter mirrors that of the high affinity galactopyranose transporter of E. coli, suggesting that this bacterium has evolved complementary transporters that enable it to use all the available galactose present during carbon limiting conditions.
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Affiliation(s)
| | - Axel Müller
- From the Department of Biology
- York Structural Biology Laboratory,and
| | | | - Jennifer R. Potts
- From the Department of Biology
- Department of Chemistry, University of York, York YO10 5YW, United Kingdom
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22
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Partha SK, van Straaten KE, Sanders DAR. Structural basis of substrate binding to UDP-galactopyranose mutase: crystal structures in the reduced and oxidized state complexed with UDP-galactopyranose and UDP. J Mol Biol 2009; 394:864-77. [PMID: 19836401 DOI: 10.1016/j.jmb.2009.10.013] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2009] [Revised: 10/07/2009] [Accepted: 10/08/2009] [Indexed: 11/25/2022]
Abstract
D-Galactofuranose (Galf) residues are found in the cell walls of pathogenic microbes such as Mycobacterium tuberculosis, and are essential for viability. UDP-galactopyranose mutase (UGM) is a unique flavo-enzyme that catalyzes the reversible conversion of UDP-galactopyranose (UDP-Galp) and UDP-galactofuranose (UDP-Galf). UDP-Galf is the active precursor of Galf residues found in cell walls. Despite the wealth of biochemical/mechanistic data generated for UGM, the structural basis of substrate binding is still lacking. Here, we report the crystal structures of UGM from Deinococcus radiodurans (drUGM) in complex with its natural substrate (UDP-Galp) and UDP. Crystal structures of drUGM:UDP-Galp complexes with oxidized and reduced FAD were determined at 2.36 A and 2.50 A resolution, respectively. The substrate is buried in the active site in an unusual folded conformation and the anomeric carbon of the galactose is at a favorable distance (2.8 A) from N5 of FAD to form an FAD-galactose adduct. The mobile loops in the substrate complex structure exist in a closed conformation. The drUGM-UDP complex structure was determined at 2.55 A resolution and its overall structure is identical with that of the oxidized and reduced complexes, including the conformation of the mobile loops. Comparison with the recently reported UGM:UDP-glucose complex structure reveals key differences and the structures reported here are likely to represent the productive/active conformation of UGM. These structures provide valuable insights into substrate recognition and a basis for understanding the mechanism. These complex structures may serve as a platform for structure-guided design of inhibitors of UGM.
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Affiliation(s)
- Sarathy Karunan Partha
- Department of Chemistry, 110 Science Place, University of Saskatchewan, Saskatoon, Canada S7N 5C9
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23
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Guyett P, Glushka J, Gu X, Bar-Peled M. Real-time NMR monitoring of intermediates and labile products of the bifunctional enzyme UDP-apiose/UDP-xylose synthase. Carbohydr Res 2009; 344:1072-8. [PMID: 19375693 DOI: 10.1016/j.carres.2009.03.026] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2009] [Revised: 03/17/2009] [Accepted: 03/23/2009] [Indexed: 11/25/2022]
Abstract
The conversion of UDP-alpha-d-glucuronic acid to UDP-alpha-d-xylose and UDP-alpha-d-apiose by a bifunctional potato enzyme UDP-apiose/UDP-xylose synthase was studied using real-time nuclear magnetic resonance (NMR) spectroscopy. UDP-alpha-d-glucuronic acid is converted via the intermediate uridine 5'-beta-l-threo-pentapyranosyl-4''-ulose diphosphate to UDP-alpha-d-apiose and simultaneously to UDP-alpha-d-xylose. The UDP-alpha-d-apiose that is formed is unstable and is converted to alpha-d-apio-furanosyl-1,2-cyclic phosphate and UMP. High-resolution real-time NMR spectroscopy is a powerful tool for the direct and quantitative characterization of previously undetected transient and labile components formed during a complex enzyme-catalyzed reaction.
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Affiliation(s)
- Paul Guyett
- Complex Carbohydrate Research Center, and BioEnergy Science Center, 315 Riverbend Road, University of Georgia, Athens, GA 30602, USA
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24
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Errey JC, Mann MC, Fairhurst SA, Hill L, McNeil MR, Naismith JH, Percy JM, Whitfield C, Field RA. Sugar nucleotide recognition by Klebsiella pneumoniae UDP-D-galactopyranose mutase: fluorinated substrates, kinetics and equilibria. Org Biomol Chem 2009; 7:1009-16. [PMID: 19225684 PMCID: PMC3326532 DOI: 10.1039/b815549f] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A series of selectively fluorinated and other substituted UDP-D-galactose derivatives have been evaluated as substrates for Klebsiella pneumoniae UDP-D-galactopyranose mutase. This enzyme, which catalyses the interconversion of the pyranose and furanose forms of galactose as its UDP adduct, is a prospective drug target for a variety of microbial infections. We show that none of the 2''-, 3''- or 6''-hydroxyl groups of UDP-D-galactopyranose are essential for substrate binding and turnover. However, steric factors appear to play an important role in limiting the range of substitutions that can be accommodated at C-2'' and C-6'' of the sugar nucleotide substrate. Attempts to invert the C-2'' stereochemistry from equatorial to axial, changing D-galacto- to D-talo-configuration, in an attempt to exploit the higher percentage of furanose at equilibrium in the talo-series, met with no turnover of substrate.
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Affiliation(s)
- James C. Errey
- School of Chemical Sciences and Pharmacy, University of East Anglia, Norwich NR4 7TJ, UK
| | - Maretta C. Mann
- School of Chemical Sciences and Pharmacy, University of East Anglia, Norwich NR4 7TJ, UK
| | | | - Lionel Hill
- Department of Metabolic Biology, John Innes Centre, Norwich NR4 7UH, UK
| | - Michael R. McNeil
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523-1619, USA
| | - James H. Naismith
- School of Chemistry and Centre for Biomolecular Sciences, University of St Andrews, North Haugh, St Andrews KY16 9ST, UK
| | - Jonathan M. Percy
- Department of Pure and Applied Chemistry, University of Strathclyde, Glasgow G1 1XLC, UK
| | - Chris Whitfield
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Robert A. Field
- School of Chemical Sciences and Pharmacy, University of East Anglia, Norwich NR4 7TJ, UK
- Department of Biological Chemistry, John Innes Centre, Norwich NR4 7UH, UK,
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25
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Eppe G, Peltier P, Daniellou R, Nugier-Chauvin C, Ferrières V, Vincent SP. Probing UDP-galactopyranose mutase binding pocket: a dramatic effect on substitution of the 6-position of UDP-galactofuranose. Bioorg Med Chem Lett 2008; 19:814-6. [PMID: 19119008 DOI: 10.1016/j.bmcl.2008.12.014] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2008] [Revised: 12/03/2008] [Accepted: 12/03/2008] [Indexed: 11/16/2022]
Abstract
UDP-galactopyranose mutase (UGM) catalyzes the isomerization of UDP-galactopyranose (UDP-Galp) into UDP-galactofuranose (UDP-Galf), an essential step of the mycobacterial cell wall biosynthesis. UDP-(6-deoxy-6-fluoro)-D-galactofuranose 1 was tested as substrate of UGM. Turnover could be observed by HPLC. The k(cat) (7.4s(-1)) and the K(m) (24 mM) of 1 were thus measured and compared with those of UDP-Galf and other fluorinated analogs. The presence of the fluorine atom at the 6-position had a moderate effect on the rate of the reaction but a huge one on the interactions between the enzyme and its substrate. This result demonstrated that key interactions occur at the vicinity of the 6-position of UDP-galactose in the Michaelis complex.
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Affiliation(s)
- Guillaume Eppe
- University of Namur (FUNDP), Département de Chimie, Laboratoire de Chimie Bio-Organique, rue de Bruxelles 61, B-5000 Namur, Belgium
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26
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Peltier P, Euzen R, Daniellou R, Nugier-Chauvin C, Ferrières V. Recent knowledge and innovations related to hexofuranosides: structure, synthesis and applications. Carbohydr Res 2008; 343:1897-923. [DOI: 10.1016/j.carres.2008.02.010] [Citation(s) in RCA: 123] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2007] [Revised: 02/08/2008] [Accepted: 02/12/2008] [Indexed: 10/22/2022]
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27
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Yuan Y, Bleile DW, Wen X, Sanders DAR, Itoh K, Liu HW, Pinto BM. Investigation of binding of UDP-Galf and UDP-[3-F]Galf to UDP-galactopyranose mutase by STD-NMR spectroscopy, molecular dynamics, and CORCEMA-ST calculations. J Am Chem Soc 2008; 130:3157-68. [PMID: 18278916 DOI: 10.1021/ja7104152] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
UDP-galactopyranose mutase (UGM) is the key enzyme involved in the biosynthesis of Galf. UDP-Galp and UDP-Galf are two natural substrates of UGM. A protocol that combines the use of STD-NMR spectroscopy, molecular modeling, and CORCEMA-ST calculations was applied to the investigation of the binding of UDP-Galf and its C3-fluorinated analogue to UGM from Klebsiella pneumoniae. UDP-Galf and UDP-[3-F]Galf were bound to UGM in a manner similar to that of UDP-Galp. The interconversions of UDP-Galf and UDP-[3-F]Galf to their galactopyranose counterparts were catalyzed by the reduced (active) UGM with different catalytic efficiencies, as observed by NMR spectroscopy. The binding affinities of UDP-Galf and UDP-[3-F]Galf were also compared with those of UDP-Galp and UDP by competition STD-NMR experiments. When UGM was in the oxidized (inactive) state, the binding affinities of UDP-Galf, UDP-Galp, and UDP-[3-F]Galf were of similar magnitudes and were lower than that of UDP. However, when UGM was in the reduced state, UDP-Galp had higher binding affinity compared with UDP. Molecular dynamics (MD) simulations indicated that the "open" mobile loop in UGM "closes" upon binding of the substrates. Combined MD simulations and STD-NMR experiments were used to create models of UGM with UDP-Galf and UDP-[3-F]Galf as bound ligands. Calculated values of saturation-transfer effects with CORCEMA-ST (complete relaxation and conformational exchange matrix analysis of saturation transfer) were compared to the experimental STD effects and permitted differentiation between two main conformational families of the bound ligands. Taken together, these results are used to rationalize the different rates of catalytic turnover of UDP-Galf and UDP-[3-F]Galf and shed light on the mechanism of action of UGM.
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Affiliation(s)
- Yue Yuan
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia, Canada V5A 1S6
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28
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Caravano A, Dohi H, Sinaÿ P, Vincent SP. A new methodology for the synthesis of fluorinated exo-glycals and their time-dependent inhibition of UDP-galactopyranose mutase. Chemistry 2007; 12:3114-23. [PMID: 16429471 DOI: 10.1002/chem.200500991] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Fluorinated carbohydrates constitute a very important class of mechanistic probes for glycosyl-processing enzymes. In this study, we describe the first synthesis of fluorinated and phosphonylated exo-glycals and their corresponding nucleotide sugars in the galactofuranose series. The synthetic protocol that we have developed is a Selectfluor-mediated fluorination/elimination sequence on phosphonylated exo-glycals, and it offers a new entry into fluorinated carbohydrate chemistry. The challenging E/Z stereochemical assignment of the resulting tetrasubstituted alkenes, which bear an alkoxy, an alkyl, a fluoro, and a phosphonyl group, has been achieved through NMR experiments. The corresponding (E)- and (Z)-nucleotide fluorosugars have been prepared and tested as inhibitors of UDP-galactopyranose mutase (UGM). UGM is a flavoenzyme that catalyzes the isomerization of uridine diphosphate(UDP)-galactopyranose into UDP-galactofuranose, a key step of the biosynthesis of important mycobacterial cell-wall glycoconjugates. The two diastereomeric molecules were found to display time-dependent inactivation of UGM, as expected from preliminary results using non-fluorinated exo-glycal nucleotides. The inhibitory properties of the two fluorinated molecules led us to suggest that the inactivation mechanism proceeds through two-electron processes, despite the presence of the flavin cofactor within the UGM catalytic site.
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Affiliation(s)
- Audrey Caravano
- Ecole Normale Supérieure, Département de Chimie, Institut de Chimie Moléculaire (FR 2769), UMR 8642: CNRS-ENS-UPMC Paris 6, 24 rue Lhomond, 75231 Paris Cedex 05, France
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29
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Synthesis of acyclic galactitol- and lyxitol-aminophosphonates as inhibitors of UDP-galactopyranose mutase. Tetrahedron Lett 2007. [DOI: 10.1016/j.tetlet.2007.04.113] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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30
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Liautard V, Desvergnes V, Martin OR. Stereoselective synthesis of alpha-C-Substituted 1,4-dideoxy-1,4-imino-D-galactitols. Toward original UDP-Galf mimics via cross-metathesis. Org Lett 2006; 8:1299-302. [PMID: 16562876 DOI: 10.1021/ol053078z] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
[reaction: see text] Various alpha-C-substituted 1,4-dideoxy-1,4-imino-d-galactitols were prepared efficiently from 1-O-acetyl-2,3,5,6-tetra-O-benzyl-d-glucofuranose by a four-step sequence involving as the key step the highly syn-selective TMSOTf-catalyzed addition of silylated nucleophiles to a glycofuranosylamine. Cross-metathesis of the alpha-C-allylated iminogalactofuranose derivative with an original uridin-5'-yl vinylphosphonate led to novel UDP-galactofuranose mimics. Such compounds are of interest as potential inhibitors of the mycobacterial galactan biosynthesis pathway.
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Affiliation(s)
- Virginie Liautard
- Institut de Chimie Organique et Analytique, UMR 6005, Université d'Orléans-CNRS Rue de Chartres, BP 6759, F-45067 Orléans Cedex 2, France
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31
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Caravano A, Sinaÿ P, Vincent SP. 1,4-Anhydrogalactopyranose is not an intermediate of the mutase catalyzed UDP-galactopyranose/furanose interconversion. Bioorg Med Chem Lett 2006; 16:1123-5. [PMID: 16377186 DOI: 10.1016/j.bmcl.2005.11.106] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2005] [Revised: 11/24/2005] [Accepted: 11/28/2005] [Indexed: 11/16/2022]
Abstract
UDP-galactopyranose mutase (UGM) catalyzes the isomerization of UDP-galactopyranose (UDP-Galp) into UDP-galactofuranose (UDP-Galf), an essential step of the mycobacterial cell wall biosynthesis. The first mechanistic assumption proposed in the literature was the involvement of 1,4-anhydrogalactose 1 as intermediate of this ring contraction. To confirm or rule out this hypothesis, we synthesized 1 and engaged it in reactions with UGM. The expected formations of UDP-Galf and UDP-Galp were never observed, thus showing that 1 is not, in fact, a low energy intermediate of this enzymatic contraction.
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Affiliation(s)
- Audrey Caravano
- Ecole Normale Supérieure, Département de Chimie, Institut de Chimie Moléculaire (FR 2769), UMR 8642: CNRS-ENS-UPMC Paris 6, 24 rue Lhomond, 75231 Paris Cedex 05, France
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32
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Sadeghi-Khomami A, Blake AJ, Wilson C, Thomas NR. Synthesis of a Carbasugar Analogue of a Putative Intermediate in the UDP-Galp-Mutase Catalyzed Isomerization. Org Lett 2005; 7:4891-4. [PMID: 16235915 DOI: 10.1021/ol0517877] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
[reaction: see text] The synthesis of the carbasugar analogue of 1,4-anhydro-beta-d-galactopyranose, a proposed intermediate in the reaction catalyzed by uridine diphosphate-alpha-d-Galp mutase, in racemic form via Diels-Alder and Barton decarboxylation chemistry is reported. This compound was found not to inhibit the mutase from Mycobacterium tuberculosis, indicating that the enzyme does not possess a 1,4-anhydro-beta-d-galactopyranose binding pocket.
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Affiliation(s)
- Ali Sadeghi-Khomami
- School of Chemistry, Centre for Biomolecular Sciences, University of Nottingham, University Park, UK
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33
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Euzen R, Ferrières V, Plusquellec D. General one-step synthesis of free hexofuranosyl 1-phosphates using unprotected 1-thioimidoyl hexofuranosides. J Org Chem 2005; 70:847-55. [PMID: 15675842 DOI: 10.1021/jo0484934] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A general one-step strategy is developed for the synthesis of hexofuranosyl 1-phosphates starting from new unprotected glycofuranosyl donors. It required first the preparation of new 1-thiohexofuranosides bearing a thioimidoyl heterocycle as a leaving group. The presence of sulfur and/or nitrogen atom(s) on the aglycon allowed remote activation of these thioglycofuranosides by anhydrous phosphoric acid and led to the target phosphates 9, 27, 29, and 30 in good to excellent selectivities and, more importantly, with very limited or no ring expansion. Moreover, this one-step phosphorylation reaction could be significantly improved by avoiding any tedious protecting group manipulations on negatively charged compounds and by focusing on a simple but general procedure of purification. This approach was applied to the diastereocontrolled synthesis of d-galacto- and d-glucofuranosyl 1-phosphates and also to the preparation of rare epimer and/or deoxy counterparts, that is, d-manno- and d-fucofuranosyl derivatives.
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Affiliation(s)
- Ronan Euzen
- Ecole Nationale Supérieure de Chimie de Rennes, UMR CNRS 6052 Synthèses et Activations de Biomolécules, Institut de Chimie de Rennes, Avenue du Général Leclerc, F-35700 Rennes, France
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34
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Veerapen N, Yuan Y, Sanders DAR, Pinto BM. Synthesis of novel ammonium and selenonium ions and their evaluation as inhibitors of UDP-galactopyranose mutase. Carbohydr Res 2004; 339:2205-17. [PMID: 15337448 DOI: 10.1016/j.carres.2004.07.012] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2004] [Accepted: 07/12/2004] [Indexed: 11/26/2022]
Abstract
The syntheses of two ammonium salts of 1,4-dideoxy-1,4-imino-d-galactitol containing erythritol sulfate side chains are described. The parent compound is a known inhibitor of the enzyme UDP-galactopyranose mutase (UDP-galactopyranose furanomutase, E.C. 5.4.99.9), which is responsible for the conversion of UDP-galactopyranose into UDP-galactofuranose and is presumably protonated in its active form. The side chain was chosen because it is present in a known sulfonium ion alpha-glucosidase inhibitor, salacinol. The syntheses of the selenonium analogues derived from 1,4-dideoxy-1,4-seleno-d-galactitol are also described. The synthetic strategy in the syntheses of all four salts involved the nucleophilic attack of a protected derivative of the alditol at the least hindered carbon of 2,4-O-benzylidene d- or l-erythritol-1,3-cyclic sulfate to give adducts that were subsequently deprotected. The importance of different protecting groups used in the various syntheses is also highlighted. Enzyme inhibition assays carried out on these compounds, and the corresponding sulfonium ions synthesized previously, show that they are poor inhibitors of UDP-galactopyranose mutase.
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Affiliation(s)
- Natacha Veerapen
- Simon Fraser University, Burnaby, British Columbia, Canada V5A 1S6
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35
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Huang Z, Zhang Q, Liu HW. Reconstitution of UDP-galactopyranose mutase with 1-deaza-FAD and 5-deaza-FAD: analysis and mechanistic implications. Bioorg Chem 2004; 31:494-502. [PMID: 14613770 DOI: 10.1016/j.bioorg.2003.08.002] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The galactofuranose moiety found in many surface constituents of microorganisms is derived from UDP-D-galactopyranose (UDP-Galp) via a unique ring contraction reaction catalyzed by a FAD-dependent UDP-Galp mutase. When the enzyme is reduced by sodium dithionite, its catalytic efficiency increases significantly. Since the overall transformation exhibits no net change in the redox state of the parties involved, how the enzyme-bound FAD plays an active role in the reaction mechanism is puzzling. In this paper, we report our study of the catalytic properties of UDP-Galp mutase reconstituted with deaza-FADs. It was found that the mutase reconstituted with FAD or 1-deazaFAD has comparable activity, while that reconstituted with 5-deazaFAD is catalytically inactive. Because 5-deazaFAD is restricted to net two-electron process, yet FAD and 1-deazaFAD can undergo concerted two-electron as well as stepwise one-electron redox reactions, the above results support a radical mechanism for the mutase catalyzed reaction. In addition, the activity of the mutase reconstituted with FAD was found to increase considerably at high pHs. These observations have allowed us to propose a new mechanism involving one-electron transfer from the reduced FAD to an oxocarbenium intermediate generated by C-1 elimination of UDP to give a hexose radical and a flavin semiquinone. Subsequent radical recombination leads to a coenzyme-substrate adduct which may play a central role to facilitate the opening and recyclization of the galactose ring. A deprotonation step, accompanied or followed the electron transfer step, to increase the nucleophilicity of the flavin radical anion may account for the activity enhancement at pH > 8.
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Affiliation(s)
- Zhishu Huang
- Division of Medicinal Chemistry, College of Pharmacy, University of Texas, Austin, TX 78712, USA
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36
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37
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Soltero-Higgin M, Carlson EE, Gruber TD, Kiessling LL. A unique catalytic mechanism for UDP-galactopyranose mutase. Nat Struct Mol Biol 2004; 11:539-43. [PMID: 15133501 DOI: 10.1038/nsmb772] [Citation(s) in RCA: 116] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2003] [Accepted: 04/08/2004] [Indexed: 11/08/2022]
Abstract
The flavoenzyme uridine 5'-diphosphate (UDP)-galactopyranose mutase (UGM) catalyzes the interconversion of UDP-galactopyranose (UDP-Galp) and UDP-galactofuranose (UDP-Galf). The latter is an essential precursor to the cell wall arabinogalactan of Mycobacterium tuberculosis. The catalytic mechanism for this enzyme had not been elucidated. Here, we provide evidence for a mechanism in which the flavin cofactor assumes a new role. Specifically, the N5 of the reduced anionic flavin cofactor captures the anomeric position of the galactose residue with release of UDP. Interconversion of the isomers occurs via a flavin-derived iminium ion. To trap this putative intermediate, we treated UGM with radiolabeled UDP-Galp and sodium cyanoborohydride; a radiolabeled flavin-galactose adduct was obtained. Ultraviolet-visible spectroscopy and mass spectrometry indicate that this product is an N5-alkyl flavin. We anticipate that the clarification of the catalytic mechanism for UGM will facilitate the development of anti-mycobacterial agents.
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Ghavami A, Chen JJW, Mario Pinto B. Synthesis of a novel class of sulfonium ions as potential inhibitors of UDP-galactopyranose mutase. Carbohydr Res 2004; 339:401-7. [PMID: 14698899 DOI: 10.1016/j.carres.2003.09.036] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Two sulfonium salts of 1,4-anhydro-4-thio-D-galactitol, with structures related to the known sulfonium salt glycosidase inhibitor, salacinol, have been synthesized as potential inhibitors of UDP-galactopyranose mutase. The synthetic strategy relies on the alkylation reaction of 1,4-anhydro-2,3,5,6-tetra-O-benzyl-4-thio-D-galactitol at the sulfur atom with 2,4-O-benzylidene-D- or -L-erythritol-1,3-cyclic sulfate. In each case, the reaction proceeded stereoselectively to yield only one stereoisomer at the stereogenic sulfur atom. The effect of the polar solvent, 1,1,1,3,3,3-hexafluoroisopropanol (HFIP), in promoting high-yielding reactions is highlighted. The target compounds are then obtained by hydrogenolysis.
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Affiliation(s)
- Ahmad Ghavami
- Department of Chemistry, Simon Fraser University, British Columbia, V5A 1S6, Burnaby, Canada
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39
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Kroutil J, Karban J, Budesínský M. Utilization of nosylepimines of 1,6-anhydro-β-d-hexopyranoses for the preparation of halogenated aminosaccharides. Carbohydr Res 2003; 338:2825-33. [PMID: 14667703 DOI: 10.1016/j.carres.2003.07.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The aziridine ring cleavage of N-nosylepimines 3 and 7 having D-allo and D-manno configurations with halides led regioselectively to N-o-nitrobenzenesulfonylated 2-halo-3-amino- and 3-halo-2-amino-2,3-dideoxy derivatives of 1,6-anhydro-beta-D-glucopyranose 8-14 in 59-81% yields. Removal of o-nitrobenzenesulfonyl protecting group with benzenethiol afforded aminosaccharides, which were converted into more stable hydrochlorides 15-18.
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Affiliation(s)
- Jirí Kroutil
- Department of Organic Chemistry, Charles University, 128 43 Prague 2, Czech Republic.
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40
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Ferrières V, Blanchard S, Fischer D, Plusquellec D. A novel synthesis of D-galactofuranosyl, D-glucofuranosyl and D-mannofuranosyl 1-phosphates based on remote activation of new and free hexofuranosyl donors. Bioorg Med Chem Lett 2002; 12:3515-8. [PMID: 12443765 DOI: 10.1016/s0960-894x(02)00822-3] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
The selective synthesis of 1,2-cis-hexofuranosyl 1-phosphates was readily accomplished according to a procedure based on the 'Remote Activation Concept'. This approach required (i) the preparation of suitable 1,2-trans-hexofuranosyl donors, so that new heterocyclic thiofuranosides were designed and synthesized, (ii) the stereocontrolled phosphorylation of the corresponding unprotected donors and (iii) the simple and fast purification of the resulting anomeric phosphates. This approach showed to be equally efficient in the galactose, glucose and mannose series.
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Affiliation(s)
- Vincent Ferrières
- Ecole Nationale Supérieure de Chimie de Rennes, UMR CNRS 6052 Synthèses et Activations de Biomolécules, Institut de Chimie de Rennes, Avenue du Général Leclerc, France.
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41
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Houseknecht JB, Lowary TL. Chemistry and biology of arabinofuranosyl- and galactofuranosyl-containing polysaccharides. Curr Opin Chem Biol 2001; 5:677-82. [PMID: 11738178 DOI: 10.1016/s1367-5931(01)00265-4] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Polysaccharides containing galactofuranosyl and arabinofuranosyl residues are key components of many microorganisms. Recent investigations have provided a greater understanding of the biosynthetic pathways by which these glycans are assembled. Concomitant with these biochemical studies, an increasing number of chemical syntheses of oligofuranosides have been reported and new methods for their assembly have been developed.
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Affiliation(s)
- J B Houseknecht
- Department of Chemistry, The Ohio State University, 100 West 18th Avenue, Columbus, OH 43210, USA
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42
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Zhang Q, Liu H. Mechanistic investigation of UDP-galactopyranose mutase from Escherichia coli using 2- and 3-fluorinated UDP-galactofuranose as probes. J Am Chem Soc 2001; 123:6756-66. [PMID: 11448178 DOI: 10.1021/ja010473l] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The galactofuranose moiety found in many surface constituents of microorganisms is derived from UDP-D-galactopyranose (UDP-Galp) via a unique ring contraction reaction catalyzed by UDP-Galp mutase. This enzyme, which has been isolated from several bacterial sources, is a flavoprotein. To study this catalysis, the cloned Escherichia coli mutase was purified and two fluorinated analogues, UDP-[2-F]Galf (9) and UDP-[3-F]Galf (10), were chemically synthesized. These two compounds were found to be substrates for the reduced UDP-Galp mutase with the Km values determined to be 65 and 861 microM for 9 and 10, respectively, and the corresponding kcat values estimated to be 0.033 and 5.7 s(-1). Since the fluorine substituent is redox inert, a mechanism initiated by the oxidation of 2-OH or 3-OH on the galactose moiety can thus be firmly ruled out. Furthermore, both 9 and 10 are poorer substrates than UDP-Galf, and the rate reduction for 9 is especially significant. This finding may be ascribed to the inductive effect of the 2-F substituent that is immediately adjacent to the anomeric center, and is consistent with a mechanism involving formation of oxocarbenium intermediates or transition states during turnover. Interestingly, under nonreducing conditions, compounds 9 and 10 are not substrates, but instead are inhibitors for the mutase. The inactivation by 10 is time-dependent, active-site-directed, and irreversible with a K(I) of 270 microM and a k(inact) of 0.19 min(-1). Since the K(I) value is similar to Km, the observed inactivation is unlikely a result of tight binding. To our surprise, the inactivated enzyme could be regenerated in the presence of dithionite, and the reduced enzyme is resistant to inactivation by these fluorinated analogues. It is possible that reduction of the enzyme-bound FAD may induce a conformational change that facilitates the breakdown of the putative covalent enzyme-inhibitor adduct to reactivate the enzyme. It is also conceivable that the reduced flavin bears a higher electron density at N-1, which may play a role in preventing the formation of the covalent adduct or facilitating its breakdown by charge stabilization of the oxocarbenium intermediates/transition states. Clearly, this study has led to the identification of a potent inactivator (10) for this enzyme, and study of its inactivation has also shed light on the possible mechanism of this mutase.
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Affiliation(s)
- Q Zhang
- Division of Medicinal Chemistry, College of Pharmacy, University of Texas, Austin, Texas 78712, USA
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Kremer L, Dover LG, Morehouse C, Hitchin P, Everett M, Morris HR, Dell A, Brennan PJ, McNeil MR, Flaherty C, Duncan K, Besra GS. Galactan biosynthesis in Mycobacterium tuberculosis. Identification of a bifunctional UDP-galactofuranosyltransferase. J Biol Chem 2001; 276:26430-40. [PMID: 11304545 DOI: 10.1074/jbc.m102022200] [Citation(s) in RCA: 121] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The cell wall of Mycobacterium tuberculosis and related genera is unique among prokaryotes, consisting of a covalently bound complex of mycolic acids, D-arabinan and D-galactan, which is linked to peptidoglycan via a special linkage unit consisting of Rhap-(1-->3)-GlcNAc-P. Information concerning the biosynthesis of this entire polymer is now emerging with the promise of new drug targets against tuberculosis. Accordingly, we have developed a galactosyltransferase assay that utilizes the disaccharide neoglycolipid acceptors beta-d-Galf-(1-->5)-beta-D-Galf-O-C(10:1) and beta-D-Galf-(1-->6)-beta-D-Galf-O-C(10:1), with UDP-Gal in conjunction with isolated membranes. Chemical analysis of the subsequent reaction products established that the enzymatically synthesized products contained both beta-D-Galf linkages ((1-->5) and (1-->6)) found within the mycobacterial cell, as well as in an alternating (1-->5) and (1-->6) fashion consistent with the established structure of the cell wall. Furthermore, through a detailed examination of the M. tuberculosis genome, we have shown that the gene product of Rv3808c, now termed glfT, is a novel UDP-galactofuranosyltransferase. This enzyme possesses dual functionality in performing both (1-->5) and (1-->6) galactofuranosyltransferase reactions with the above neoglycolipid acceptors, using membranes isolated from the heterologous host Escherichia coli expressing Rv3808c. Thus, at a biochemical and genetic level, the polymerization of the galactan region of the mycolyl-arabinogalactan complex has been defined, allowing the possibility of further studies toward substrate recognition and catalysis and assay development. Ultimately, this may also lead to a more rational approach to drug design to be explored in the context of mycobacterial infections.
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Affiliation(s)
- L Kremer
- Department of Microbiology and Immunology, University of Newcastle upon Tyne, Newcastle upon Tyne, NE2 4HH, United Kingdom
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