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Synthesis and evaluation of inhibitors of Mycobacterium tuberculosis UGM using bioisosteric replacement. Bioorg Med Chem 2022; 69:116896. [DOI: 10.1016/j.bmc.2022.116896] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 06/08/2022] [Accepted: 06/20/2022] [Indexed: 11/22/2022]
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2
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Biosynthesis of β-(1→5)-Galactofuranosyl Chains of Fungal-Type and O-Mannose-Type Galactomannans within the Invasive Pathogen Aspergillus fumigatus. mSphere 2020; 5:5/1/e00770-19. [PMID: 31941812 PMCID: PMC6968653 DOI: 10.1128/msphere.00770-19] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
β-(1→5)-Galactofuranosyl residues are widely distributed in the subphylum Pezizomycotina of the phylum Ascomycota. Pezizomycotina includes many plant and animal pathogens. Although the structure of β-(1→5)-galactofuranosyl residues of galactomannans in filamentous fungi was discovered long ago, it remains unclear which enzyme is responsible for biosynthesis of this glycan. Fungal cell wall formation processes are complicated, and information concerning glycosyltransferases is essential for understanding them. In this study, we showed that GfsA and GfsC are responsible for the biosynthesis of all β-(1→5)-galactofuranosyl residues of fungal-type and O-mannose-type galactomannans. The data presented here indicate that β-(1→5)-galactofuranosyl residues are involved in cell growth, conidiation, polarity, and cell surface hydrophobicity. Our new understanding of β-(1→5)-galactofuranosyl residue biosynthesis provides important novel insights into the formation of the complex cell wall structure and the virulence of the members of the subphylum Pezizomycotina. The pathogenic fungus Aspergillus fumigatus contains galactomannans localized on the surface layer of its cell walls, which are involved in various biological processes. Galactomannans comprise α-(1→2)-/α-(1→6)-mannan and β-(1→5)-/β-(1→6)-galactofuranosyl chains. We previously revealed that GfsA is a β-galactofuranoside β-(1→5)-galactofuranosyltransferase involved in the biosynthesis of β-(1→5)-galactofuranosyl chains. In this study, we clarified the biosynthesis of β-(1→5)-galactofuranosyl chains in A. fumigatus. Two paralogs exist within A. fumigatus: GfsB and GfsC. We show that GfsB and GfsC, in addition to GfsA, are β-galactofuranoside β-(1→5)-galactofuranosyltransferases by biochemical and genetic analyses. GfsA, GfsB, and GfsC can synthesize β-(1→5)-galactofuranosyl oligomers at up to lengths of 7, 3, and 5 galactofuranoses within an established in vitro highly efficient assay of galactofuranosyltransferase activity. Structural analyses of galactomannans extracted from ΔgfsB, ΔgfsC, ΔgfsAC, and ΔgfsABC strains revealed that GfsA and GfsC synthesized all β-(1→5)-galactofuranosyl residues of fungal-type and O-mannose-type galactomannans and that GfsB exhibited limited function in A. fumigatus. The loss of β-(1→5)-galactofuranosyl residues decreased the hyphal growth rate and conidium formation ability and increased the abnormal hyphal branching structure and cell surface hydrophobicity, but this loss is dispensable for sensitivity to antifungal agents and virulence toward immunocompromised mice. IMPORTANCE β-(1→5)-Galactofuranosyl residues are widely distributed in the subphylum Pezizomycotina of the phylum Ascomycota. Pezizomycotina includes many plant and animal pathogens. Although the structure of β-(1→5)-galactofuranosyl residues of galactomannans in filamentous fungi was discovered long ago, it remains unclear which enzyme is responsible for biosynthesis of this glycan. Fungal cell wall formation processes are complicated, and information concerning glycosyltransferases is essential for understanding them. In this study, we showed that GfsA and GfsC are responsible for the biosynthesis of all β-(1→5)-galactofuranosyl residues of fungal-type and O-mannose-type galactomannans. The data presented here indicate that β-(1→5)-galactofuranosyl residues are involved in cell growth, conidiation, polarity, and cell surface hydrophobicity. Our new understanding of β-(1→5)-galactofuranosyl residue biosynthesis provides important novel insights into the formation of the complex cell wall structure and the virulence of the members of the subphylum Pezizomycotina.
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3
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Biosynthesis of Galactan in Mycobacterium tuberculosis as a Viable TB Drug Target? Antibiotics (Basel) 2020; 9:antibiotics9010020. [PMID: 31935842 PMCID: PMC7168186 DOI: 10.3390/antibiotics9010020] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 12/27/2019] [Accepted: 01/02/2020] [Indexed: 12/21/2022] Open
Abstract
While target-based drug design has proved successful in several therapeutic areas, this approach has not yet provided compelling outcomes in the field of antibacterial agents. This statement remains especially true for the development of novel therapeutic interventions against tuberculosis, an infectious disease that is among the top ten leading causes of death globally. Mycobacterial galactan is an important component of the protective cell wall core of the tuberculosis pathogen and it could provide a promising target for the design of new drugs. In this review, we summarize the current knowledge on galactan biosynthesis in Mycobacterium tuberculosis, including landmark findings that led to the discovery and understanding of three key enzymes in this pathway: UDP-galactose mutase, and galactofuranosyl transferases GlfT1 and GlfT2. Moreover, we recapitulate the efforts aimed at their inhibition. The predicted common transition states of the three enzymes provide the lucrative possibility of multitargeting in pharmaceutical development, a favourable property in the mitigation of drug resistance. We believe that a tight interplay between target-based computational approaches and experimental methods will result in the development of original inhibitors that could serve as the basis of a new generation of drugs against tuberculosis.
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Chen WJ, Han SB, Xie ZB, Huang HS, Jiang DH, Gong SS, Sun Q. Efficient Synthesis of UDP-Furanoses via 4,5-Dicyanoimidazole(DCI)-Promoted Coupling of Furanosyl-1-Phosphates with Uridine Phosphoropiperidate. Molecules 2019; 24:molecules24040655. [PMID: 30781738 PMCID: PMC6412210 DOI: 10.3390/molecules24040655] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 02/10/2019] [Accepted: 02/11/2019] [Indexed: 11/16/2022] Open
Abstract
A P(V)-N activation method based on nucleoside phosphoropiperidate/DCI system has been developed for improved synthesis of diverse UDP-furanoses. The reaction conditions including temperature, amount of activator, and reaction time were optimized to alleviate the degradation of UDP-furanoses to cyclic phosphates. In addition, an efficient and facile phosphoramidite route was employed for the preparation of furanosyl-1-phosphates.
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Affiliation(s)
- Wei-Jie Chen
- Jiangxi Key Laboratory of Organic Chemistry, Jiangxi Science and Technology Normal University, 605 Fenglin Avenue, Nanchang 330013, China.
| | - Shuai-Bo Han
- Jiangxi Key Laboratory of Organic Chemistry, Jiangxi Science and Technology Normal University, 605 Fenglin Avenue, Nanchang 330013, China.
| | - Zhen-Biao Xie
- Jiangxi Key Laboratory of Organic Chemistry, Jiangxi Science and Technology Normal University, 605 Fenglin Avenue, Nanchang 330013, China.
| | - Hua-Shan Huang
- Jiangxi Key Laboratory of Organic Chemistry, Jiangxi Science and Technology Normal University, 605 Fenglin Avenue, Nanchang 330013, China.
| | - Duo-Hua Jiang
- Jiangxi Key Laboratory of Organic Chemistry, Jiangxi Science and Technology Normal University, 605 Fenglin Avenue, Nanchang 330013, China.
| | - Shan-Shan Gong
- Jiangxi Key Laboratory of Organic Chemistry, Jiangxi Science and Technology Normal University, 605 Fenglin Avenue, Nanchang 330013, China.
| | - Qi Sun
- Jiangxi Key Laboratory of Organic Chemistry, Jiangxi Science and Technology Normal University, 605 Fenglin Avenue, Nanchang 330013, China.
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5
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Li LX, Rautengarten C, Heazlewood JL, Doering TL. Xylose donor transport is critical for fungal virulence. PLoS Pathog 2018; 14:e1006765. [PMID: 29346417 PMCID: PMC5773217 DOI: 10.1371/journal.ppat.1006765] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Accepted: 11/22/2017] [Indexed: 12/22/2022] Open
Abstract
Cryptococcus neoformans, an AIDS-defining opportunistic pathogen, is the leading cause of fungal meningitis worldwide and is responsible for hundreds of thousands of deaths annually. Cryptococcal glycans are required for fungal survival in the host and for pathogenesis. Most glycans are made in the secretory pathway, although the activated precursors for their synthesis, nucleotide sugars, are made primarily in the cytosol. Nucleotide sugar transporters are membrane proteins that solve this topological problem, by exchanging nucleotide sugars for the corresponding nucleoside phosphates. The major virulence factor of C. neoformans is an anti-phagocytic polysaccharide capsule that is displayed on the cell surface; capsule polysaccharides are also shed from the cell and impede the host immune response. Xylose, a neutral monosaccharide that is absent from model yeast, is a significant capsule component. Here we show that Uxt1 and Uxt2 are both transporters specific for the xylose donor, UDP-xylose, although they exhibit distinct subcellular localization, expression patterns, and kinetic parameters. Both proteins also transport the galactofuranose donor, UDP-galactofuranose. We further show that Uxt1 and Uxt2 are required for xylose incorporation into capsule and protein; they are also necessary for C. neoformans to cause disease in mice, although surprisingly not for fungal viability in the context of infection. These findings provide a starting point for deciphering the substrate specificity of an important class of transporters, elucidate a synthetic pathway that may be productively targeted for therapy, and contribute to our understanding of fundamental glycobiology.
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Affiliation(s)
- Lucy X. Li
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | | | | | - Tamara L. Doering
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, United States of America
- * E-mail:
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6
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Sharma S, Erickson KM, Troutman JM. Complete Tetrasaccharide Repeat Unit Biosynthesis of the Immunomodulatory Bacteroides fragilis Capsular Polysaccharide A. ACS Chem Biol 2017; 12:92-101. [PMID: 28103676 DOI: 10.1021/acschembio.6b00931] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Capsular polysaccharide A (CPSA) is a four-sugar repeating unit polymer found on the surface of the gut symbiont Bacteroides fragilis that has therapeutic potential in animal models of autoimmune disorders. This therapeutic potential has been credited to its zwitterionic character derived from a positively charged N-acetyl-4-aminogalactosamine (AADGal) and a negatively charged 4,6-O-pyruvylated galactose (PyrGal). In this report, using a fluorescent polyisoprenoid chemical probe, the complete enzymatic assembly of the CPSA tetrasaccharide repeat unit is achieved. The proposed pyruvyltransferase, WcfO; galactopyranose mutase, WcfM; and glycosyltransferases, WcfP and WcfN, encoded by the CPSA biosynthesis gene cluster were heterologously expressed and functionally characterized. Pyruvate modification, catalyzed by WcfO, was found to occur on galactose of the polyisoprenoid-linked disaccharide (AADGal-Gal), and did not occur on galactose linked to uridine diphosphate (UDP) or a set of nitrophenyl-galactose analogues. This pyruvate modification was also found to be required for the incorporation of the next sugar in the pathway N-acetylgalactosamine (GalNAc) by the glycosyltransferase WcfP. The pyruvate acetal modification of a galactose has not been previously explored in the context of a polysaccharide biosynthesis pathway, and this work demonstrates the importance of this modification to repeat unit assembly. Upon production of the polyisoprenoid-linked AADGal-PyrGal-GalNAc, the proteins WcfM and WcfN were found to work in concert to form the final tetrasaccharide, where WcfM formed UDP-galactofuranose (Galf) and WcfN transfers Galf to the AADGal-PyrGal-GalNAc. This work demonstrates the first enzymatic assembly of the tetrasaccharide repeat unit of CPSA in a sequential single pot reaction.
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Affiliation(s)
- Sunita Sharma
- Department
of Chemistry, ‡The Center for Biomedical Engineering and Science, §Department of Biological Sciences, ∥Nanoscale Science
Program, University of North Carolina at Charlotte, 9201 University
City Blvd., Charlotte, North
Carolina 28223, United States
| | - Katelyn M. Erickson
- Department
of Chemistry, ‡The Center for Biomedical Engineering and Science, §Department of Biological Sciences, ∥Nanoscale Science
Program, University of North Carolina at Charlotte, 9201 University
City Blvd., Charlotte, North
Carolina 28223, United States
| | - Jerry M. Troutman
- Department
of Chemistry, ‡The Center for Biomedical Engineering and Science, §Department of Biological Sciences, ∥Nanoscale Science
Program, University of North Carolina at Charlotte, 9201 University
City Blvd., Charlotte, North
Carolina 28223, United States
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7
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Wesener DA, Levengood MR, Kiessling LL. Comparing Galactan Biosynthesis in Mycobacterium tuberculosis and Corynebacterium diphtheriae. J Biol Chem 2016; 292:2944-2955. [PMID: 28039359 DOI: 10.1074/jbc.m116.759340] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2016] [Revised: 12/28/2016] [Indexed: 11/06/2022] Open
Abstract
The suborder Corynebacterineae encompasses species like Corynebacterium glutamicum, which has been harnessed for industrial production of amino acids, as well as Corynebacterium diphtheriae and Mycobacterium tuberculosis, which cause devastating human diseases. A distinctive component of the Corynebacterineae cell envelope is the mycolyl-arabinogalactan (mAG) complex. The mAG is composed of lipid mycolic acids, and arabinofuranose (Araf) and galactofuranose (Galf) carbohydrate residues. Elucidating microbe-specific differences in mAG composition could advance biotechnological applications and lead to new antimicrobial targets. To this end, we compare and contrast galactan biosynthesis in C. diphtheriae and M. tuberculosis In each species, the galactan is constructed from uridine 5'-diphosphate-α-d-galactofuranose (UDP-Galf), which is generated by the enzyme UDP-galactopyranose mutase (UGM or Glf). UGM and the galactan are essential in M. tuberculosis, but their importance in Corynebacterium species was not known. We show that small molecule inhibitors of UGM impede C. glutamicum growth, suggesting that the galactan is critical in corynebacteria. Previous cell wall analysis data suggest the galactan polymer is longer in mycobacterial species than corynebacterial species. To explore the source of galactan length variation, a C. diphtheriae ortholog of the M. tuberculosis carbohydrate polymerase responsible for the bulk of galactan polymerization, GlfT2, was produced, and its catalytic activity was evaluated. The C. diphtheriae GlfT2 gave rise to shorter polysaccharides than those obtained with the M. tuberculosis GlfT2. These data suggest that GlfT2 alone can influence galactan length. Our results provide tools, both small molecule and genetic, for probing and perturbing the assembly of the Corynebacterineae cell envelope.
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Affiliation(s)
| | - Matthew R Levengood
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706
| | - Laura L Kiessling
- From the Department of Biochemistry and .,Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706
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8
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Misra S, Valicherla GR, Mohd Shahab, Gupta J, Gayen JR, Misra-Bhattacharya S. UDP-galactopyranose mutase, a potential drug target against human pathogenic nematodeBrugia malayi. Pathog Dis 2016; 74:ftw072. [DOI: 10.1093/femspd/ftw072] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/13/2016] [Indexed: 01/02/2023] Open
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9
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Genetic analysis of capsular polysaccharide synthesis gene clusters in 79 capsular types of Klebsiella spp. Sci Rep 2015; 5:15573. [PMID: 26493302 PMCID: PMC4616057 DOI: 10.1038/srep15573] [Citation(s) in RCA: 157] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Accepted: 09/28/2015] [Indexed: 11/15/2022] Open
Abstract
A total of 79 capsular types have been reported in Klebsiella spp., whereas capsular polysaccharide synthesis (cps) regions were available in only 22 types. Due to the limitations of serotyping, complete repertoire of cps will be helpful for capsular genotyping. We therefore resolved the rest 57 cps and conducted comparative analysis. Clustering results of 1,515 predicted proteins from cps loci categorized proteins which share similarity into homology groups (HGs) revealing that 77 Wzy polymerases were classified into 56 HGs, which indicate the high specificity of wzy between different types. Accordingly, wzy-based capsular genotyping could differentiate capsule types except for those lacking wzy (K29 and K50), those sharing identical wzy (K22 vs. K37); and should be carefully applied in those exhibited high similarity (K12 vs. K41, K2 vs. K13, K74 vs. K80, K79 vs. KN1 and K30 vs. K69). Comparison of CPS structures in several capsular types that shared similarity in their gene contents implies possible functions of glycosyltransferases. Therefore, our results provide complete set of cps in various types of Klebsiella spp., which enable the understandings of relationship between genes and CPS structures and are useful for identification of documented or new capsular types.
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10
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Kincaid VA, London N, Wangkanont K, Wesener DA, Marcus SA, Héroux A, Nedyalkova L, Talaat AM, Forest KT, Shoichet BK, Kiessling LL. Virtual Screening for UDP-Galactopyranose Mutase Ligands Identifies a New Class of Antimycobacterial Agents. ACS Chem Biol 2015. [PMID: 26214585 DOI: 10.1021/acschembio.5b00370] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Galactofuranose (Galf) is present in glycans critical for the virulence and viability of several pathogenic microbes, including Mycobacterium tuberculosis, yet the monosaccharide is absent from mammalian glycans. Uridine 5'-diphosphate-galactopyranose mutase (UGM) catalyzes the formation of UDP-Galf, which is required to produce Galf-containing glycoconjugates. Inhibitors of UGM have therefore been sought, both as antimicrobial leads and as tools to delineate the roles of Galf in cells. Obtaining cell permeable UGM probes by either design or high throughput screens has been difficult, as has elucidating how UGM binds small molecule, noncarbohydrate inhibitors. To address these issues, we employed structure-based virtual screening to uncover new inhibitor chemotypes, including a triazolothiadiazine series. These compounds are among the most potent antimycobacterial UGM inhibitors described. They also facilitated determination of a UGM-small molecule inhibitor structure, which can guide optimization. A comparison of results from the computational screen and a high-throughput fluorescence polarization (FP) screen indicated that the scaffold hits from the former had been evaluated in the FP screen but missed. By focusing on promising compounds, the virtual screen rescued false negatives, providing a blueprint for generating new UGM probes and therapeutic leads.
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Affiliation(s)
- Virginia A. Kincaid
- Department
of Biochemistry, University of Wisconsin—Madison, Madison, Wisconsin 53706, United States
| | - Nir London
- Department
of Pharmaceutical Chemistry, University of California—San Francisco, San Francisco, California 94158, United States
| | - Kittikhun Wangkanont
- Department
of Chemistry, University of Wisconsin—Madison, Madison, Wisconsin 53706, United States
| | - Darryl A. Wesener
- Department
of Biochemistry, University of Wisconsin—Madison, Madison, Wisconsin 53706, United States
| | - Sarah A. Marcus
- Department
of Pathobiological Sciences, University of Wisconsin—Madison, Madison, Wisconsin 53706, United States
| | - Annie Héroux
- Photon
Sciences Directorate, Brookhaven National Laboratories, Upton, New York 11973, United States
| | - Lyudmila Nedyalkova
- Ontario Institute
of Cancer Research and Faculty of Pharmacy, University of Toronto, Toronto, Canada
| | - Adel M. Talaat
- Department
of Pathobiological Sciences, University of Wisconsin—Madison, Madison, Wisconsin 53706, United States
| | - Katrina T. Forest
- Department
of Bacteriology, University of Wisconsin—Madison, Madison, Wisconsin 53706, United States
| | - Brian K. Shoichet
- Department
of Pharmaceutical Chemistry, University of California—San Francisco, San Francisco, California 94158, United States
- Ontario Institute
of Cancer Research and Faculty of Pharmacy, University of Toronto, Toronto, Canada
| | - Laura L. Kiessling
- Department
of Biochemistry, University of Wisconsin—Madison, Madison, Wisconsin 53706, United States
- Department
of Chemistry, University of Wisconsin—Madison, Madison, Wisconsin 53706, United States
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11
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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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12
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Abstract
Nematodes represent a diverse phylum of both free living and parasitic species. While the species Caenorhabditis elegans is a valuable model organism, parasitic nematodes or helminths pose a serious threat to human health. Indeed, helminths cause many neglected tropical diseases that afflict humans. Nematode glycoconjugates have been implicated in evasive immunomodulation, a hallmark of nematode infections. One monosaccharide residue present in the glycoconjugates of several human pathogens is galactofuranose (Galf). This five-membered ring isomer of galactose has not been detected in mammals, making Galf metabolic enzymes attractive therapeutic targets. The only known pathway for biosynthetic incorporation of Galf into glycoconjugates depends upon generation of the glycosyl donor UDP-Galf by the flavoenzyme uridine 5'-diphosphate (UDP) galactopyranose mutase (UGM or Glf). A putative UGM encoding gene (glf-1) was recently identified in C. elegans. We sought to assess the catalytic activity of the corresponding gene product (CeUGM). CeUGM catalyzes the isomerization of UDP-Galf and UDP-galactopyranose (UDP-Galp). In the presence of enzyme, substrate, and a hydride source, a galactose-N5-FAD adduct was isolated, suggesting the CeUGM flavin adenine dinucleotide (FAD) cofactor serves as a nucleophile in covalent catalysis. Homology modeling and protein variants indicate that CeUGM possesses an active site similar to that of prokaryotic enzymes, despite the low sequence identity (∼15%) between eukaryotic and prokaryotic UGM proteins. Even with the primary sequence differences, heterocyclic UGM inhibitors developed against prokaryotic proteins also inhibit CeUGM activity. We postulate that inhibitors of CeUGM can serve as chemical probes of Galf in nematodes and as anthelmintic leads. The available data suggest that CeUGM facilitates the biosynthetic incorporation of Galf into nematode glycoconjugates through generation of the glycosyl donor UDP-Galf.
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Affiliation(s)
- Darryl A. Wesener
- Department of Biochemistry, University of Wisconsin–Madison, 433 Babcock Drive, Madison, WI 53706-1544 USA
| | - John F. May
- Department of Biochemistry, University of Wisconsin–Madison, 433 Babcock Drive, Madison, WI 53706-1544 USA
| | - Elizabeth M. Huffman
- Department of Chemistry, University of Wisconsin–Madison, 1101 University Avenue, Madison, WI 53706-1322 USA
| | - Laura L. Kiessling
- Department of Biochemistry, University of Wisconsin–Madison, 433 Babcock Drive, Madison, WI 53706-1544 USA
- Department of Chemistry, University of Wisconsin–Madison, 1101 University Avenue, Madison, WI 53706-1322 USA
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13
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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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14
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Tefsen B, Ram AF, van Die I, Routier FH. Galactofuranose in eukaryotes: aspects of biosynthesis and functional impact. Glycobiology 2011; 22:456-69. [DOI: 10.1093/glycob/cwr144] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
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15
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Abstract
Carbohydrates in the thermodynamically disfavored furanose ring conformation are not present in mammalian glycoconjugates, but are widespread in the glycans produced by many bacterial pathogens. In bacteria, these furanose sugars are often found in cell surface glycoconjugates, and are essential for the viability or virulence of the organisms. As a result, the enzymes involved in the biosynthesis of bacterial furanosides are attractive targets as potential selective antimicrobial chemotherapeutics. However, before such chemotherapeutics can be designed, synthesized, and evaluated, more information about the activity and specificity of these enzymes is required. This chapter describes assays that have been used to study enzymes involved in the biosynthesis of one of the most abundant naturally occurring furanose residues, galactofuranose (Galf). In particular, the focus is on UDP-galactopyranose mutase and galactofuranosyltransferases. The assays described in this chapter require UDP-galactofuranose (UDP-Galf); therefore, a procedure for the preparation of UDP-Galf, as well as various UDP-Galf derivatives, using a three-enzyme chemoenzymatic procedure, is also described.
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Affiliation(s)
- Myles B Poulin
- The Alberta Ingenuity Centre for Carbohydrate Science, Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada
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16
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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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Poulin MB, Nothaft H, Hug I, Feldman MF, Szymanski CM, Lowary TL. Characterization of a bifunctional pyranose-furanose mutase from Campylobacter jejuni 11168. J Biol Chem 2009; 285:493-501. [PMID: 19887444 DOI: 10.1074/jbc.m109.072157] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
UDP-galactopyranose mutases (UGM) are the enzymes responsible for the synthesis of UDP-galactofuranose (UDP-Galf) from UDP-galactopyranose (UDP-Galp). The enzyme, encoded by the glf gene, is present in bacteria, parasites, and fungi that express Galf in their glycoconjugates. Recently, a UGM homologue encoded by the cj1439 gene has been identified in Campylobacter jejuni 11168, an organism possessing no Galf-containing glycoconjugates. However, the capsular polysaccharide from this strain contains a 2-acetamido-2-deoxy-d-galactofuranose (GalfNAc) moiety. Using an in vitro high performance liquid chromatography assay and complementation studies, we characterized the activity of this UGM homologue. The enzyme, which we have renamed UDP-N-acetylgalactopyranose mutase (UNGM), has relaxed specificity and can use either UDP-Gal or UDP-GalNAc as a substrate. Complementation studies of mutase knock-outs in C. jejuni 11168 and Escherichia coli W3110, the latter containing Galf residues in its lipopolysaccharide, demonstrated that the enzyme recognizes both UDP-Gal and UDP-GalNAc in vivo. A homology model of UNGM and site-directed mutagenesis led to the identification of two active site amino acid residues involved in the recognition of the UDP-GalNAc substrate. The specificity of UNGM was characterized using a two-substrate co-incubation assay, which demonstrated, surprisingly, that UDP-Gal is a better substrate than UDP-GalNAc.
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Affiliation(s)
- Myles B Poulin
- Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2R3, Canada
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18
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Engel J, Schmalhorst PS, Dörk-Bousset T, Ferrières V, Routier FH. A single UDP-galactofuranose transporter is required for galactofuranosylation in Aspergillus fumigatus. J Biol Chem 2009; 284:33859-68. [PMID: 19840949 DOI: 10.1074/jbc.m109.070219] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Galactofuranose (Galf) containing molecules have been described at the cell surface of several eukaryotes and shown to contribute to the virulence of the parasite Leishmania major and the fungus Aspergillus fumigatus. It is anticipated that a number of the surface glycoconjugates such as N-glycans or glycolipids are galactofuranosylated in the Golgi apparatus. This raises the question of how the substrate for galactofuranosylation reactions, UDP-Galf, which is synthesized in the cytosol, translocates into the organelles of the secretory pathway. Here we report the first identification of a Golgi-localized nucleotide sugar transporter, named GlfB, with specificity for a UDP-Galf. In vitro transport assays established binding of UDP-Galf to GlfB and excluded transport of several other nucleotide sugars. Furthermore, the implication of glfB in the galactofuranosylation of A. fumigatus glycoconjugates and galactomannan was demonstrated by a targeted gene deletion approach. Our data reveal a direct connection between galactomannan and the organelles of the secretory pathway that strongly suggests that the cell wall-bound polysaccharide originates from its glycosylphosphatidylinositol-anchored form.
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Affiliation(s)
- Jakob Engel
- Institute for Cellular Chemistry, Hannover Medical School, 30625 Hannover, Germany
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Shu HY, Fung CP, Liu YM, Wu KM, Chen YT, Li LH, Liu TT, Kirby R, Tsai SF. Genetic diversity of capsular polysaccharide biosynthesis in Klebsiella pneumoniae clinical isolates. MICROBIOLOGY-SGM 2009; 155:4170-4183. [PMID: 19744990 DOI: 10.1099/mic.0.029017-0] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Klebsiella pneumoniae is an enteric pathogen causing community-acquired and hospital-acquired infections in humans. Epidemiological studies have revealed significant diversity in capsular polysaccharide (CPS) type and clinical manifestation of K. pneumoniae infection in different geographical areas of the world. We have sequenced the capsular polysaccharide synthesis (cps) region of seven clinical isolates and compared the sequences with the publicly available cps sequence data of five strains: NTUH-K2044 (K1 serotype), Chedid (K2 serotype), MGH78578 (K52 serotype), A1142 (K57 serotype) and A1517. Among all strains, six genes at the 5' end of the cps clusters that encode proteins for CPS transportation and processing at the bacterial surface are highly similar to each other. The central region of the cps gene clusters, which encodes proteins for polymerization and assembly of the CPS subunits, is highly divergent. Based on the collected sequence, we found that either the wbaP gene or the wcaJ gene exists in a given K. pneumoniae strain, suggesting that there is a major difference in the CPS biosynthesis pathway and that the K. pneumoniae strains can be classified into at least two distinct groups. All isolates contain gnd, encoding gluconate-6-phosphate dehydrogenase, at the 3' end of the cps gene clusters. The rmlBADC genes were found in CPS K9-positive, K14-positive and K52-positive strains, while manC and manB were found in K1, K2, K5, K14, K62 and two undefined strains. Our data indicate that, while overall genomic organization is similar between different pathogenic K. pneumoniae strains, the genetic variation of the sugar moiety and polysaccharide linkage generate the diversity in CPS molecules that could help evade host immune attack.
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Affiliation(s)
- Hung-Yu Shu
- Genome Research Center, National Yang-Ming University, Taipei, Taiwan, ROC.,Department of Bioscience Technology, Chang Jung Christian University, Tainan County, Taiwan, ROC
| | - Chang-Phone Fung
- Institute of Tropical Medicine, School of Medicine, National Yang-Ming University, Taipei, Taiwan, ROC.,Division of Infectious Diseases, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan, ROC
| | - Yen-Ming Liu
- Division of Molecular and Genomic Medicine, National Health Research Institutes, Zhunan, Miaoli County, Taiwan, ROC
| | - Keh-Ming Wu
- Institute of Biomedical Informatics, National Yang-Ming University, Taipei, Taiwan, ROC.,Division of Molecular and Genomic Medicine, National Health Research Institutes, Zhunan, Miaoli County, Taiwan, ROC
| | - Ying-Tsong Chen
- Division of Molecular and Genomic Medicine, National Health Research Institutes, Zhunan, Miaoli County, Taiwan, ROC
| | - Ling-Hui Li
- Division of Molecular and Genomic Medicine, National Health Research Institutes, Zhunan, Miaoli County, Taiwan, ROC
| | - Tze-Tze Liu
- Genome Research Center, National Yang-Ming University, Taipei, Taiwan, ROC
| | - Ralph Kirby
- Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, Taipei, Taiwan, ROC
| | - Shih-Feng Tsai
- Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, Taipei, Taiwan, ROC.,Division of Molecular and Genomic Medicine, National Health Research Institutes, Zhunan, Miaoli County, Taiwan, ROC.,Genome Research Center, National Yang-Ming University, Taipei, Taiwan, ROC.,Institute of Biomedical Informatics, National Yang-Ming University, Taipei, Taiwan, ROC
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Ligand binding and substrate discrimination by UDP-galactopyranose mutase. J Mol Biol 2009; 391:327-40. [PMID: 19500588 DOI: 10.1016/j.jmb.2009.05.081] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2009] [Revised: 05/20/2009] [Accepted: 05/27/2009] [Indexed: 11/23/2022]
Abstract
Galactofuranose (Galf) residues are present in cell wall glycoconjugates of numerous pathogenic microbes. Uridine 5'-diphosphate (UDP) Galf, the biosynthetic precursor of Galf-containing glycoconjugates, is produced from UDP-galactopyranose (UDP-Galp) by the flavoenzyme UDP-galactopyranose mutase (UGM). The gene encoding UGM (glf) is essential for the viability of pathogens, including Mycobacterium tuberculosis, and this finding underscores the need to understand how UGM functions. Considerable effort has been devoted to elucidating the catalytic mechanism of UGM, but progress has been hindered by a lack of structural data for an enzyme-substrate complex. Such data could reveal not only substrate binding interactions but how UGM can act preferentially on two very different substrates, UDP-Galp and UDP-Galf, yet avoid other structurally related UDP sugars present in the cell. Herein, we describe the first structure of a UGM-ligand complex, which provides insight into the catalytic mechanism and molecular basis for substrate selectivity. The structure of UGM from Klebsiella pneumoniae bound to the substrate analog UDP-glucose (UDP-Glc) was solved by X-ray crystallographic methods and refined to 2.5 A resolution. The ligand is proximal to the cofactor, a finding that is consistent with a proposed mechanism in which the reduced flavin engages in covalent catalysis. Despite this proximity, the glucose ring of the substrate analog is positioned such that it disfavors covalent catalysis. This orientation is consistent with data indicating that UDP-Glc is not a substrate for UGM. The relative binding orientations of UDP-Galp and UDP-Glc were compared using saturation transfer difference NMR. The results indicate that the uridine moiety occupies a similar location in both ligand complexes, and this relevant binding mode is defined by our structural data. In contrast, the orientations of the glucose and galactose sugar moieties differ. To understand the consequences of these differences, we derived a model for the productive UGM-substrate complex that highlights interactions that can contribute to catalysis and substrate discrimination.
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Peltier P, Guégan JP, Daniellou R, Nugier-Chauvin C, Ferrières V. Stereoselective Chemoenzymatic Synthesis of UDP-1,2-cis-furanoses from α,β-Furanosyl 1-Phosphates. European J Org Chem 2008. [DOI: 10.1002/ejoc.200800742] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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22
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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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Development of a coupled spectrophotometric assay for GlfT2, a bifunctional mycobacterial galactofuranosyltransferase. Carbohydr Res 2008; 343:2130-9. [PMID: 18423586 DOI: 10.1016/j.carres.2008.03.023] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2008] [Revised: 03/13/2008] [Accepted: 03/17/2008] [Indexed: 11/22/2022]
Abstract
As a key constituent of their protective cell wall all mycobacteria produce a large structural component, the mycolyl-arabinogalactan (mAG) complex, which has at its core a galactan moiety of alternating beta-(1-->5) and beta-(1-->6) galactofuranosyl residues. Galactan biosynthesis is essential for mycobacterial viability and thus inhibitors of the enzymes involved in its assembly are potential drugs for the treatment of mycobacterial diseases, including tuberculosis. Only two galactofuranosyltransferases, GlfT1 and GlfT2, are responsible for the biosynthesis of the entire galactan domain of the mAG and we report here the first high-throughput assay for GlfT2. Successful implementation of the assay required the synthesis of multi-milligram amounts of the donor for the enzyme, UDP-Galf, 1, which was achieved using a chemoenzymatic approach. We also describe an improved expression system for GlfT2, which provides a larger amount of active protein for the assay. Kinetic analysis of 1 and a known trisaccharide acceptor for the enzyme, 2, have been carried out and the apparent K(m) and k(cat) values obtained for the latter are in agreement with those obtained using a previously reported radiochemical assay. The assay has been implemented in 384-well microtiter plates, which will facilitate the screening of large numbers of potential GlfT2 inhibitors, with possible utility as novel anti-TB drugs.
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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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25
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Lopez G, Nugier-Chauvin C, Rémond C, O'Donohue M. Investigation of the specificity of an α-l-arabinofuranosidase using C-2 and C-5 modified α-l-arabinofuranosides. Carbohydr Res 2007; 342:2202-11. [PMID: 17601513 DOI: 10.1016/j.carres.2007.06.001] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2007] [Revised: 05/25/2007] [Accepted: 06/02/2007] [Indexed: 10/23/2022]
Abstract
The synthesis of three novel glycosyl donors presenting the same scaffold as alpha-L-arabinofuranose but modified at the C-2 or C-5 positions has been achieved. Furthermore, chemoenzymatic syntheses using the alpha-L-arabinofuranosidase AbfD3 and these unnatural furanosides were investigated. The use of the novel p-nitrophenyl furanoside donors revealed that AbfD3 can perform transglycosylation with the C-5 deoxygenated donor but not with the C-2 modified one. These results emphasize the vital role for OH-2 in AbfD3 substrate recognition.
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Affiliation(s)
- Gérald Lopez
- Ecole Nationale Supérieure de Chimie de Rennes, UMR CNRS 6226 Sciences Chimiques de Rennes, Equipe Synthèse Organique et Systèmes Organisés, Avenue du Général Leclerc, F-35700 Rennes, France
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26
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Desvergnes S, Desvergnes V, Martin OR, Itoh K, Liu HW, Py S. Stereoselective synthesis of β-1-C-substituted 1,4-dideoxy-1,4-imino-d-galactitols and evaluation as UDP-galactopyranose mutase inhibitors. Bioorg Med Chem 2007; 15:6443-9. [PMID: 17662609 DOI: 10.1016/j.bmc.2007.06.059] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2007] [Revised: 06/19/2007] [Accepted: 06/26/2007] [Indexed: 10/23/2022]
Abstract
The synthesis of 1-C-substituted 1,4-dideoxy-1,4-imino-D-galactitols involving nitrone umpolung is described. The SmI(2)-induced key coupling proved highly stereoselective in favor of the beta-C-substituted products bearing a three-carbon chain at the pseudoanomeric position. Pyrrolidines 9 and 10, as well as the bicyclic compounds 8 and 11, exhibit weak inhibition of the activity of the UDP-galactopyranose mutase from Escherichia coli.
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Affiliation(s)
- Stéphanie Desvergnes
- Département de Chimie Moléculaire (SERCO) UMR-5250, ICMG FR-2607, CNRS--Université Joseph Fourier, BP 53, F-38041 Grenoble Cedex 9, France
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27
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Barry CE, Crick DC, McNeil MR. Targeting the formation of the cell wall core of M. tuberculosis. Infect Disord Drug Targets 2007; 7:182-202. [PMID: 17970228 PMCID: PMC4747060 DOI: 10.2174/187152607781001808] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Mycobacteria have a unique cell wall, which is rich in drug targets. The cell wall core consists of a peptidoglycan layer, a mycolic acid layer, and an arabinogalactan polysaccharide connecting them. The detailed structure of the cell wall core is largely, although not completely, understood and will be presented. The biosynthetic pathways of all three components reveal significant drug targets that are the basis of present drugs and/or have potential for new drugs. These pathways will be reviewed and include enzymes involved in polyisoprene biosynthesis, soluble arabinogalactan precursor production, arabinogalactan polymerization, fatty acid synthesis, mycolate maturation, and soluble peptidoglycan precursor formation. Information relevant to targeting all these enzymes will be presented in tabular form. Selected enzymes will then be discussed in more detail. It is thus hoped this chapter will aid in the selection of targets for new drugs to combat tuberculosis.
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Affiliation(s)
- Clifton E. Barry
- Tuberculosis Research Section, Laboratory of Host Defense, NIAID, NIH, Twinbrook 2, Room 239, 12441 Parklawn Drive, Rockville, MD 20852
| | - Dean C. Crick
- Mycobacterial Research Laboratories, Dept. of Microbiology, Immunology, and Pathology, 1682 Campus Delivery, Colorado State University, Fort Collins, CO 80523-1682
| | - Michael R. McNeil
- Mycobacterial Research Laboratories, Dept. of Microbiology, Immunology, and Pathology, 1682 Campus Delivery, Colorado State University, Fort Collins, CO 80523-1682
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Mikusová K, Belánová M, Korduláková J, Honda K, McNeil MR, Mahapatra S, Crick DC, Brennan PJ. Identification of a novel galactosyl transferase involved in biosynthesis of the mycobacterial cell wall. J Bacteriol 2006; 188:6592-8. [PMID: 16952951 PMCID: PMC1595490 DOI: 10.1128/jb.00489-06] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The possibility of the Rv3782 protein of Mycobacterium tuberculosis being a putative galactosyl transferase (GalTr) implicated in galactan synthesis arose from its similarity to the known GalTr Rv3808c, its classification as a nucleotide sugar-requiring inverting glycosyltransferase (GT-2 family), and its location within the "possible arabinogalactan biosynthetic gene cluster" of M. tuberculosis. In order to study the function of the enzyme, active membrane and cell wall fractions from Mycobacterium smegmatis containing the overexpressed Rv3782 protein were incubated with endogenous decaprenyldiphosphoryl-N-acetylglucosaminyl-rhamnose (C(50)-P-P-GlcNAc-Rha) as the primary substrate for galactan synthesis and UDP-[(14)C]galactopyranose as the immediate precursor of UDP-[(14)C]galactofuranose, the ultimate source of all of the galactofuranose (Galf) units of galactan. Obvious increased and selective synthesis of C(50)-P-P-GlcNAc-Rha-Galf-Galf, the earliest product in the pathway leading to the fully polymerized galactan, was observed, suggesting that Rv3782 encodes a GalTr involved in the first stages of galactan synthesis. Time course experiments pointed to a possible bifunctional enzyme responsible for the initial synthesis of C(50)-P-P-GlcNAc-Rha-Galf, followed by immediate conversion to C(50)-P-P-GlcNAc-Rha-Galf-Galf. Thus, Rv3782 appears to be the initiator of galactan synthesis, while Rv3808c continues with the subsequent polymerization events.
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Affiliation(s)
- Katarína Mikusová
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO 80523, USA
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29
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Euzen R, Lopez G, Nugier-Chauvin C, Ferrières V, Plusquellec D, Rémond C, O’Donohue M. A Chemoenzymatic Approach for the Synthesis of Unnatural Disaccharides ContainingD-Galacto- orD-Fucofuranosides. European J Org Chem 2005. [DOI: 10.1002/ejoc.200500525] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Beverley SM, Owens KL, Showalter M, Griffith CL, Doering TL, Jones VC, McNeil MR. Eukaryotic UDP-galactopyranose mutase (GLF gene) in microbial and metazoal pathogens. EUKARYOTIC CELL 2005; 4:1147-54. [PMID: 15947206 PMCID: PMC1151986 DOI: 10.1128/ec.4.6.1147-1154.2005] [Citation(s) in RCA: 112] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Galactofuranose (Gal(f)) is a novel sugar absent in mammals but present in a variety of pathogenic microbes, often within glycoconjugates that play critical roles in cell surface formation and the infectious cycle. In prokaryotes, Gal(f) is synthesized as the nucleotide sugar UDP-Gal(f) by UDP-galactopyranose mutase (UGM) (gene GLF). Here we used a combinatorial bioinformatics screen to identify a family of candidate eukaryotic GLFs that had previously escaped detection. GLFs from three pathogens, two protozoa (Leishmania major and Trypanosoma cruzi) and one fungus (Cryptococcus neoformans), had UGM activity when expressed in Escherichia coli and assayed in vivo and/or in vitro. Eukaryotic GLFs are closely related to each other but distantly related to prokaryotic GLFs, showing limited conservation of core residues around the substrate-binding site and flavin adenine dinucleotide binding domain. Several eukaryotes not previously investigated for Gal(f) synthesis also showed strong GLF homologs with conservation of key residues. These included other fungi, the alga Chlamydomonas and the algal phleovirus Feldmannia irregularis, parasitic nematodes (Brugia, Onchocerca, and Strongyloides) and Caenorhabditis elegans, and the urochordates Halocynthia and Cionia. The C. elegans open reading frame was shown to encode UGM activity. The GLF phylogenetic distribution suggests that Gal(f) synthesis may occur more broadly in eukaryotes than previously supposed. Overall, GLF/Gal(f) synthesis in eukaryotes appears to occur with a disjunct distribution and often in pathogenic species, similar to what is seen in prokaryotes. Thus, UGM inhibition may provide an attractive drug target in those eukaryotes where Gal(f) plays critical roles in cellular viability and virulence.
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Affiliation(s)
- Stephen M Beverley
- Department of Molecular Microbiology, Washington University Medical School, 660 S. Euclid Ave., St. Louis, MO 63110, USA.
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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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Mariño K, Marino C, Lima C, Baldoni L, de Lederkremer RM. The First Chemical Synthesis of UDP[6-3H]-α-D-galactofuranose. European J Org Chem 2005. [DOI: 10.1002/ejoc.200500056] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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33
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Moyrand F, Janbon G. UGD1, encoding the Cryptococcus neoformans UDP-glucose dehydrogenase, is essential for growth at 37 degrees C and for capsule biosynthesis. EUKARYOTIC CELL 2005; 3:1601-8. [PMID: 15590833 PMCID: PMC539039 DOI: 10.1128/ec.3.6.1601-1608.2004] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We report the identification and disruption of the Cryptococcus neoformans var. grubii UGD1 gene encoding the UDP-glucose dehydrogenase, which catalyzes the conversion of UDP-glucose into UDP-glucuronic acid. Deletion of UGD1 led to modifications in the cell wall, as revealed by changes in the sensitivity of ugd1Delta cells to sodium dodecyl sulfate, NaCl, and sorbitol. Moreover, two of the yeast's major virulence factors-capsule biosynthesis and the ability to grow at 37 degrees C-were impaired in ugd1Delta strains. These results suggest that the UDP-dehydrogenase represents the major, and maybe only, biosynthetic pathway for UDP-glucuronic acid in C. neoformans. Consequently, deletion of UGD1 blocked not only the synthesis of UDP-glucuronic acid but also that of UDP-xylose. To differentiate the phenotype(s) associated with the UDP-glucuronic acid defect alone from those linked to the UDP-xylose defect, ugd1Delta mutants were phenotypically compared to strains from which the gene encoding UDP-xylose synthase (i.e., that required for synthesis of UDP-xylose) had been deleted. Finally, studies of strains from which one of the four CAP genes (CAP10, CAP59, CAP60, or CAP64) had been deleted revealed common cell wall phenotypes associated with the acapsular state.
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Affiliation(s)
- Frédérique Moyrand
- Unité de Mycologie Moléculaire, Institut Pasteur, 25 rue du Dr-Roux, F-75724 Paris Cedex 15, France
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34
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Ballell L, Field RA, Duncan K, Young RJ. New small-molecule synthetic antimycobacterials. Antimicrob Agents Chemother 2005; 49:2153-63. [PMID: 15917508 PMCID: PMC1140552 DOI: 10.1128/aac.49.6.2153-2163.2005] [Citation(s) in RCA: 133] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Affiliation(s)
- Lluis Ballell
- Pharmaceutical Sciences Faculty, Medicinal Chemistry Group, Sorbonnelaan 16, Utrecht University, Utrecht 3584 CA, The Netherlands.
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35
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Feng L, Senchenkova SN, Yang J, Shashkov AS, Tao J, Guo H, Cheng J, Ren Y, Knirel YA, Reeves PR, Wang L. Synthesis of the heteropolysaccharide O antigen of Escherichia coli O52 requires an ABC transporter: structural and genetic evidence. J Bacteriol 2004; 186:4510-9. [PMID: 15231783 PMCID: PMC438562 DOI: 10.1128/jb.186.14.4510-4519.2004] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The structural and genetic organization of the Escherichia coli O52 O antigen was studied. As identified by sugar and methylation analysis and nuclear magnetic resonance spectroscopy, the O antigen of E. coli O52 has a partially O-acetylated disaccharide repeating unit (O unit) containing D-fucofuranose and 6-deoxy-D-manno-heptopyranose, as well as a minor 6-deoxy-3-O-methylhexose (most likely, 3-O-methylfucose). The O-antigen gene cluster of E. coli O52, which is located between the galF and gnd genes, was found to contain putative genes for the synthesis of the O-antigen constituents, sugar transferase genes, and ABC-2 transporter genes. Further analysis confirmed that O52 employs an ATP-binding cassette (ABC) transporter-dependent pathway for translocation and polymerization of the O unit. This is the first report of an ABC transporter being involved in translocation of a heteropolysaccharide O antigen in E. coli. Genes specific for E. coli O52 were also identified.
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Affiliation(s)
- Lu Feng
- TEDA School of Biological Sciences and Biotechnology, Nankai University, Tianjin Biochip Technology Corporation, Tianjin, People's Republic of China
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Yagi T, Mahapatra S, Mikusova K, Crick DC, Brennan PJ. Polymerization of mycobacterial arabinogalactan and ligation to peptidoglycan. J Biol Chem 2003; 278:26497-504. [PMID: 12719430 DOI: 10.1074/jbc.m302216200] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [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 spp. consists predominately of arabinogalactan chains linked at the reducing ends to peptidoglycan via a P-GlcNAc-(alpha1-3)-Rha linkage unit (LU) and esterified to a variety of mycolic acids at the nonreducing ends. Several aspects of the biosynthesis of this complex have been defined, including the initial formation of the LU on a polyprenyl phosphate (Pol-P) molecule followed by the sequential addition of galactofuranosyl (Galf) units to generate Pol-P-P-LU-(Galf)1,2,3, etc. and Pol-P-P-LU-galactan, catalyzed by a bifunctional galactosyltransferase (Rv3808c) capable of adding alternating 5- and 6-linked Galf units. By applying cell-free extracts of Mycobacterium smegmatis, containing cell wall and membrane fragments, and differential labeling with UDP-[14C]Galp and recombinant UDP-Galp mutase as the source of [14C]Galf for galactan biosynthesis and 5-P-[14C]ribosyl-P-P as a donor of [14C]Araf for arabinan synthesis, we now demonstrate sequential synthesis of the simpler Pol-P-P-LU-(Galf)n glycolipid intermediates followed by the Pol-P-P-LU-arabinogalactan and, finally, ligation of the P-LU-arabinogalactan to peptidoglycan. This first time demonstration of in vitro ligation of newly synthesized P-LU-arabinogalactan to newly synthesized peptidoglycan is a necessary forerunner to defining the genetics and enzymology of cell wall polymer-peptidoglycan ligation in Mycobacterium spp. and examining this step as a target for new antibacterial drugs.
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Affiliation(s)
- Tetsuya Yagi
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, Colorado 80523-1682, USA
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37
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Scherman MS, Winans KA, Stern RJ, Jones V, Bertozzi CR, McNeil MR. Drug targeting Mycobacterium tuberculosis cell wall synthesis: development of a microtiter plate-based screen for UDP-galactopyranose mutase and identification of an inhibitor from a uridine-based library. Antimicrob Agents Chemother 2003; 47:378-82. [PMID: 12499218 PMCID: PMC148999 DOI: 10.1128/aac.47.1.378-382.2003] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A microtiter plate assay for UDP-galactopyranose mutase, an essential cell wall biosynthetic enzyme of Mycobacterium tuberculosis, was developed. The assay is based on the release of tritiated formaldehyde from UDP-galactofuranose but not UDP-galactopyranose by periodate and was used to identify a uridine-based enzyme inhibitor from a chemical library.
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Affiliation(s)
- Michael S Scherman
- Department of Microbiology, Colorado State University, Fort Collins, Colorado 80523, USA
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38
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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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39
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Mariño K, Lima C, Maldonado S, Marino C, de Lederkremer RM. Influence of exo beta-D-galactofuranosidase inhibitors in cultures of Penicillium fellutanum and modifications in hyphal cell structure. Carbohydr Res 2002; 337:891-7. [PMID: 12007471 DOI: 10.1016/s0008-6215(02)00073-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We have examined beta-D-galactofuranosidase production by Penicillium fellutanum in the presence of D-galactono-1,4-lactone or 4-aminophenyl 1-thio-beta-D-galactofuranoside, two potent in vitro inhibitors of the enzyme. Activity of the enzyme in the culture filtrate was increased by 35% when glucose was replaced by D-galactose as the carbon source, and the activity diminished 80% of the control value when the inhibitors were added. Significant alterations of the culture were observed: (a) the medium became increasingly opalescent due to the secretion of a protein aggregate (PA) which contained 15% neutral sugar, mainly ribose; (b) the peptidophosphogalactomannan (pPGM) containing galactofuranose, normally produced by P. fellutanum, could not be obtained from the culture medium in the presence of the inhibitors; (c) the content of galactofuranose in the cell wall was significantly decreased in the presence of D-galactono-1,4-lactone. The influence on the mycelia growth was investigated by light microscopy (LM) and transmission electron microscopy (TEM) showing important alterations.
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Affiliation(s)
- Karina Mariño
- CIHIDECAR, Departamento de Química Orgánica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Pabellón II, Ciudad Universitaria, 1428, Buenos Aires, Argentina
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40
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Pathak AK, Pathak V, Seitz L, Maddry JA, Gurcha SS, Besra GS, Suling WJ, Reynolds RC. Studies on (beta,1-->5) and (beta,1-->6) linked octyl Gal(f) disaccharides as substrates for mycobacterial galactosyltransferase activity. Bioorg Med Chem 2001; 9:3129-43. [PMID: 11711288 DOI: 10.1016/s0968-0896(01)00179-1] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The emergence of multi-drug resistant (MDR) strains of Mycobacterium tuberculosis (MTB) and the continuing pandemic of tuberculosis emphasizes the urgent need for the development of new anti-tubercular agents with novel drug targets. The recent structural elucidation of the mycobacterial cell wall highlights a large variety of structurally unique components that may be a basis for new drug development. This publication describes the synthesis, characterization, and screening of several octyl Galf(beta,1-->5)Galf and octyl Galf(beta,1-->6)Galf derivatives. A cell-free assay system has been utilized for galactosyltransferase activity using UDP[14C]Galf as the glycosyl donor, and in vitro inhibitory activity has been determined in a colorimetric broth microdilution assay system against MTB H37Ra and three clinical isolates of Mycobacterium avium complex (MAC). Certain derivatives showed moderate activities against MTB and MAC. The biological evaluation of these disaccharides suggests that more hydrophobic analogues with a blocked reducing end showed better activity as compared to totally deprotected disaccharides that more closely resemble the natural substrates in cell wall biosynthesis.
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Affiliation(s)
- A K Pathak
- Department of Organic Chemistry, Southern Research Institute, PO Box 55305, Birmingham, AL 35255-5305, USA
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41
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Abstract
[reaction: see text] A reliable and efficient synthetic route to UDP-alpha-D-galactofuranose (UDP-Galf) has been developed. Reaction of UMP-N-methylimidazolide with Galf 1-phosphate proceeds rapidly to provide UDP-Galf with excellent reproducibility and in a yield approximately twice as high as those reported previously.
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Affiliation(s)
- A L Marlow
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI 53706, USA
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42
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Pan F, Jackson M, Ma Y, McNeil M. Cell wall core galactofuran synthesis is essential for growth of mycobacteria. J Bacteriol 2001; 183:3991-8. [PMID: 11395463 PMCID: PMC95282 DOI: 10.1128/jb.183.13.3991-3998.2001] [Citation(s) in RCA: 189] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The mycobacterial cell wall core consists of an outer lipid (mycolic acid) layer attached to peptidoglycan via a galactofuranosyl-containing polysaccharide, arabinogalactan. This structural arrangement strongly suggests that galactofuranosyl residues are essential for the growth and viability of mycobacteria. Galactofuranosyl residues are formed in nature by a ring contraction of UDP-galactopyranose to UDP-galactofuranose catalyzed by the enzyme UDP-galactopyranose mutase (Glf). In Mycobacterium tuberculosis the glf gene overlaps, by 1 nucleotide, a gene, Rv3808c, that has been shown to encode a galactofuranosyl transferase. We demonstrate here that glf can be knocked out in Mycobacterium smegmatis by allelic replacement only in the presence of two rescue plasmids carrying functional copies of glf and Rv3808c. The glf rescue plasmid was designed with a temperature-sensitive origin of replication and the M. smegmatis glf knockout mutant is unable to grow at the higher temperature at which the glf-containing rescue plasmid is lost. In a separate experiment, the Rv3808c rescue plasmid was designed with a temperature-sensitive origin of replication and the glf-bearing plasmid was designed with a normal original of replication; this strain was also unable to grow at the nonpermissive temperature. Thus, both glf and Rv3808c are essential for growth. These findings and the fact that galactofuranosyl residues are not found in humans supports the development of UDP-galactopyranose mutase and galactofuranosyl transferase as important targets for the development of new antituberculosis drugs.
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Affiliation(s)
- F Pan
- Department of Microbiology, Colorado State University, Fort Collins, Colorado 80523, USA
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43
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Guan S, Clarke AJ, Whitfield C. Functional analysis of the galactosyltransferases required for biosynthesis of D-galactan I, a component of the lipopolysaccharide O1 antigen of Klebsiella pneumoniae. J Bacteriol 2001; 183:3318-27. [PMID: 11344139 PMCID: PMC99629 DOI: 10.1128/jb.183.11.3318-3327.2001] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
D-Galactan I is an O-antigenic polymer with the repeat unit structure [-->3)-beta-D-Galf-(1-->3)-alpha-D-Galp-(1-->], that is found in the lipopolysaccharide of Klebsiella pneumoniae O1 and other gram-negative bacteria. A genetic locus containing six genes is responsible for the synthesis and assembly of D-galactan I via an ATP-binding cassette (ABC) transporter-dependent pathway. The galactosyltransferase activities that are required for the processive polymerization of D-galactan I were identified by using in vitro reactions. The activities were determined with endogenous lipid acceptors in membrane preparations from Escherichia coli K-12 expressing individual enzymes (or combinations of enzymes) or in membranes reconstituted with specific lipid acceptors. The D-galactan I polymer is built on a lipid acceptor, undecaprenyl pyrophosphoryl-GlcpNAc, a product of the WecA enzyme that participates in the biosynthesis of enterobacterial common antigen and O-antigenic polysaccharide (O-PS) biosynthesis pathways. This intermediate is directed into D-galactan I biosynthesis by the bifunctional wbbO gene product, which sequentially adds one Galp and one Galf residue from the corresponding UDP-sugars to form a lipid-linked trisaccharide. The two galactosyltransferase activities of WbbO are separable by limiting the UDP-Galf precursor. Galactosyltransferase activity in membranes reconstituted with exogenous lipid-linked trisaccharide acceptor and the known structure of D-galactan I indicate that WbbM catalyzes the subsequent transfer of a single Galp residue to form a lipid-linked tetrasaccharide. Chain extension of the D-galactan I polymer requires WbbM for Galp transferase, together with Galf transferase activity provided by WbbO. Comparison of the biosynthetic pathways for D-galactan I and the polymannose E. coli O9a antigen reveals some interesting features that may reflect a common theme in ABC transporter-dependent O-PS assembly systems.
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Affiliation(s)
- S Guan
- Department of Microbiology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
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44
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Zhang Q, Liu HW. Chemical synthesis of UDP-beta-L-arabinofuranose and its turnover to UDP-beta-L-arabinopyranose by UDP-galactopyranose mutase. Bioorg Med Chem Lett 2001; 11:145-9. [PMID: 11206446 DOI: 10.1016/s0960-894x(00)00616-8] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Uridine-5'-diphospho-beta-L-arabinofuranose, a possible donor of L-arabinofuranose residues in plants, was synthesized. This compound, in the presence of UDP-galactopyranose mutase, underwent interconversion with UDP-beta-L-arabinopyranose that is a likely precursor of L-arabinofuranose in vivo. This result provided a working model for the biogenesis of arabinofuranose in plants.
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Affiliation(s)
- Q Zhang
- Department of Chemistry, University of Minnesota, Minneapolis 55455, USA
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45
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Kovensky J, Sinaÿ P. Synthesis of Galactofuranosides by Regioselective Ring Opening of a 1,4-Anhydrogalactopyranose Derivative: A Possible Chemical Model for an Unprecedented Enzymatic Reaction. European J Org Chem 2000. [DOI: 10.1002/1099-0690(200011)2000:21<3523::aid-ejoc3523>3.0.co;2-c] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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46
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Mikusová K, Yagi T, Stern R, McNeil MR, Besra GS, Crick DC, Brennan PJ. Biosynthesis of the galactan component of the mycobacterial cell wall. J Biol Chem 2000; 275:33890-7. [PMID: 10934214 DOI: 10.1074/jbc.m006875200] [Citation(s) in RCA: 96] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The structural core of the cell walls of Mycobacterium spp. consists of peptidoglycan bound by a linker unit (-alpha-L-Rhap-(1-->3)-D-GlcNAc-P-) to a galactofuran, which in turn is attached to arabinofuran and mycolic acids. The sequence of reactions leading to the biogenesis of this complex starts with the formation of the linker unit on a polyprenyl-P to produce polyprenyl-P-P-GlcNAc-Rha (Mikusová, K., Mikus, M., Besra, G. S., Hancock, I., and Brennan, P. J. (1996) J. Biol. Chem. 271, 7820-7828). We now establish that formation of the galactofuran takes place on this intermediate with UDP-Galf as the Galf donor presented in the form of UDP-Galp and UDP-Galp mutase (the glf gene product) and is catalyzed by galactofuranosyl transferases, one of which, the Mycobacterium tuberculosis H37Rv3808c gene product, has been identified. Evidence is also presented for the growth of the arabinofuran on this polyprenyl-P-P-linker unit-galactan intermediate catalyzed by unidentified arabinosyl transferases, with decaprenyl-P-Araf or 5-P-ribosyl-PP as the Araf donor. The product of these steps, the lipid-linked-LU-galactan-arabinan has been partially characterized in terms of its heterogeneity, size, and composition. Biosynthesis of the major components of mycobacterial cell walls is proving to be extremely complex. However, partial definition of arabinogalactan synthesis, the site of action of several major anti-tuberculosis drugs, facilitates the present day thrust for new drugs to counteract multiple drug-resistant tuberculosis.
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Affiliation(s)
- K Mikusová
- Department of Microbiology, Colorado State University, Fort Collins, Colorado 80523-1677, USA
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47
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Barlow JN, Blanchard JS. Enzymatic synthesis of UDP-(3-deoxy-3-fluoro)-D-galactose and UDP-(2-deoxy-2-fluoro)-D-galactose and substrate activity with UDP-galactopyranose mutase. Carbohydr Res 2000; 328:473-80. [PMID: 11093703 DOI: 10.1016/s0008-6215(00)00135-x] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The novel UDP-sugar uridine 5'-(3-deoxy-3-fluoro-D-galactopyranosyl diphosphate) (1) and UDP-(2-deoxy-2-fluoro)-D-galactose (2) have been prepared enzymatically and tested as substrate analogues for the enzyme UDP-galactopyranose mutase (UDP-Galp mutase EC 5.4.99.9). Turnover of both 1 and 2 by UDP-Galp mutase was observed by HPLC and 19F NMR. The HPLC elution profile and 19F chemical shift of the products are consistent with the formation of the predicted furanose forms of 1 and 2. The Km values for compounds 1 and 2 were similar to those of the natural substrate UDP-Galp (0.26 mM for 1, 0.2 mM for 2, and 0.6 mM for UDP-Galp), but the values for kcat were substantially different (1.6/min for 1, 0.02/min for 2, and 1364/min for UDP-Galp). A correlation was also observed between the equilibrium yield of product formed during turnover of UDP-sugar by UDP-Galp mutase (UDP-Galp, compound 1 or compound 2), and the amount of furanose present for the free sugar at thermal equilibrium in aqueous solution, using 1H and 19F NMR spectroscopy. The implications of these results to the mechanism of the unusual enzymatic reaction are discussed.
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Affiliation(s)
- J N Barlow
- Department of Biochemistry, Albert Einstein College of Medicine, Bronx, NY 10461, USA
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48
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Hemming FW, Wallis GL, Peberdy JF. An unambiguous microassay of galactofuranose residues in glycoconjugates using mild methanolysis and high pH anion-exchange chromatography. Anal Biochem 2000; 279:136-41. [PMID: 10706782 DOI: 10.1006/abio.1999.4415] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
An original, unambiguous microassay of galactofuranose (Galf) residues in glycoconjugates is described. The method involves mild acid methanolysis (5 mM HCl) for 3 h at 84 degrees C followed by high pH anion-exchange chromatography using a routine monosaccharide system. The methanolysis products Mealpha-Galf and Mebeta-Galf were characterized chromatographically by comparison with the authentic compounds and by their response to treatment with mild acid and with beta-galactofuranosidase. Testing against p-nitrophenyl-beta-Galf and UDPalpha-Galf showed the method to be applicable to both alpha- and beta- galactofuranosides over the range 10-200 pmol. The results of partial mild methanolysis over shorter periods were consistent with initial inversion of anomeric configuration at methylation followed by anomerization to an equilibrium mixture of alpha- and beta-forms. When applied to a sample of invertase from Aspergillus nidulans, the method indicated that all of the mild acid-labile galactose (78% of the total galactose present) was in the form of a galactofuranoside and that much of this was in the beta-configuration. As expected, when applied to asialofetuin (known to contain galactose only in the pyranoside form, Galp), NPalpha-Galp, NPbeta-Galp, or UDPalpha-Galp, mild acid methanolysis failed to produce any galactofuranoside.
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Affiliation(s)
- F W Hemming
- School of Biomedical Sciences, Medical School, University of Nottingham, Nottingham, NG7 2UH, United Kingdom.
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49
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Häusler H, Kawakami RP, Mlaker E, Severn WB, Wrodnigg TM, Stütz AE. Sugar Analogues with Basic Nitrogen in The Ring as Anti-Infectives. J Carbohydr Chem 2000. [DOI: 10.1080/07328300008544092] [Citation(s) in RCA: 12] [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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50
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Lee RE, Smith MD, Pickering L, Fleet GW. An approach to combinatorial library generation of galactofuranose mimics as potential inhibitors of mycobacterial cell wall biosynthesis: Synthesis of a peptidomimetic of uridine 5′-diphosphogalactofuranose (UDP-Galf). Tetrahedron Lett 1999. [DOI: 10.1016/s0040-4039(99)01844-4] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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