1
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Kelly SD, Allas MJ, Goodridge LD, Lowary TL, Whitfield C. Structure, biosynthesis and regulation of the T1 antigen, a phase-variable surface polysaccharide conserved in many Salmonella serovars. Nat Commun 2024; 15:6504. [PMID: 39090110 PMCID: PMC11294581 DOI: 10.1038/s41467-024-50957-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2024] [Accepted: 07/22/2024] [Indexed: 08/04/2024] Open
Abstract
The bacterial genus Salmonella includes diverse isolates with multiple variations in the structure of the main polysaccharide component (O antigen) of membrane lipopolysaccharides. In addition, some isolates produce a transient (T) antigen, such as the T1 polysaccharide identified in the 1960s in an isolate of Salmonella enterica Paratyphi B. The structure and biosynthesis of the T1 antigen have remained enigmatic. Here, we use biophysical, biochemical and genetic methods to show that the T1 antigen is a complex linear glycan containing tandem homopolymeric domains of galactofuranose and ribofuranose, linked to lipid A-core, like a typical O antigen. T1 is a phase-variable antigen, regulated by recombinational inversion of the promoter upstream of the T1 genetic locus through a mechanism not observed for other bacterial O antigens. The T1 locus is conserved across many Salmonella isolates, but is mutated or absent in most typhoidal serovars and in serovar Enteritidis.
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Affiliation(s)
- Steven D Kelly
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada
| | - Mikel Jason Allas
- Department of Chemistry, University of Alberta, Edmonton, AB, Canada
- Institute of Biological Chemistry, Academia Sinica, Nangang, Taipei, Taiwan
| | | | - Todd L Lowary
- Department of Chemistry, University of Alberta, Edmonton, AB, Canada.
- Institute of Biological Chemistry, Academia Sinica, Nangang, Taipei, Taiwan.
- Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan.
| | - Chris Whitfield
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ON, Canada.
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2
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Kelly SD, Williams DM, Zhu S, Kim T, Jana M, Nothof J, Thota VN, Lowary TL, Whitfield C. Klebsiella pneumoniae O-polysaccharide biosynthesis highlights the diverse organization of catalytic modules in ABC transporter-dependent glycan assembly. J Biol Chem 2024; 300:107420. [PMID: 38815868 PMCID: PMC11231755 DOI: 10.1016/j.jbc.2024.107420] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2024] [Revised: 05/10/2024] [Accepted: 05/19/2024] [Indexed: 06/01/2024] Open
Abstract
Klebsiella pneumoniae provides influential prototypes for lipopolysaccharide O antigen (OPS) biosynthesis in Gram-negative bacteria. Sequences of OPS-biosynthesis gene clusters in serotypes O4 and O7 suggest fundamental differences in the organization of required enzyme modules compared to other serotypes. Furthermore, some required activities were not assigned by homology shared with characterized enzymes. The goal of this study was therefore to resolve the serotype O4 and O7 pathways to expand our broader understanding of glycan polymerization and chain termination processes. The O4 and O7 antigens were produced from cloned genetic loci in recombinant Escherichia coli. Systematic in vivo and in vitro approaches were then applied to assign each enzyme in each of the pathways, defining the necessary components for polymerization and chain termination. OPS assembly is accomplished by multiprotein complexes formed by interactions between polymerase components variably distributed in single and multimodule proteins. In each complex, a terminator function is present in a protein containing a characteristic coiled-coil molecular ruler, which determines glycan chain length. In serotype O4, we discovered a CMP-α-3-deoxy-ᴅ-manno-octulosonic acid-dependent chain-terminating glycosyltransferase that is the founding member of a new glycosyltransferase family (GT137) and potentially identifies a new glycosyltransferase fold. The O7 OPS is terminated by a methylphosphate moiety, like the K. pneumoniae O3 antigen, but the methyltransferase-kinase enzyme pairs responsible for termination in these serotypes differ in sequence and predicted structures. Together, the characterization of O4 and O7 has established unique enzyme activities and provided new insight into glycan-assembly strategies that are widely distributed in bacteria.
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Affiliation(s)
- Steven D Kelly
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Danielle M Williams
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Shawna Zhu
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Taeok Kim
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada
| | - Manas Jana
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada
| | - Jeremy Nothof
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada
| | | | - Todd L Lowary
- Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada; Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan; Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan.
| | - Chris Whitfield
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada.
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3
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Lu K, Wang X, Zhou Y, Zhu Q. Genomic characterization and probiotic potential assessment of an exopolysaccharide-producing strain Pediococcus pentosaceus LL-07 isolated from fermented meat. BMC Microbiol 2024; 24:142. [PMID: 38664612 PMCID: PMC11044368 DOI: 10.1186/s12866-024-03304-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Accepted: 04/12/2024] [Indexed: 04/29/2024] Open
Abstract
BACKGROUND The genomic information available for Pediococcus pentosaceus is primarily derived from fermented fruits and vegetables, with less information available from fermented meat. P. pentosaceus LL-07, a strain isolated from fermented meat, has the capability of producing exopolysaccharides (EPS). To assess the probiotic attributes of P. pentosaceus LL-07, we conducted whole-genome sequencing (WGS) using the PacBio SequelIIe and Illumina MiSeq platforms, followed by in vitro experiments to explore its probiotic potential. RESULTS The genome size of P. pentosaceus LL-07 is 1,782,685 bp, comprising a circular chromosome and a circular plasmid. Our investigation revealed the absence of a CRISPR/Cas system. Sugar fermentation experiments demonstrated the characteristics of carbohydrate metabolism. P. pentosaceus LL-07 contains an EPS synthesis gene cluster consisting of 13 genes, which is different from the currently known gene cluster structure. NO genes associated with hemolysis or toxin synthesis were detected. Additionally, eighty-six genes related to antibiotic resistance were identified but not present in the prophage, transposon or plasmid. In vitro experiments demonstrated that P. pentosaceus LL-07 was comparable to the reference strain P. pentosaceus ATCC25745 in terms of tolerance to artificial digestive juice and bile, autoaggregation and antioxidation, and provided corresponding genomic evidence. CONCLUSION This study confirmed the safety and probiotic properties of P. pentosaceus LL-07 via complete genome and phenotype analysis, supporting its characterization as a potential probiotic candidate.
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Affiliation(s)
- Kuan Lu
- Key Laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), College of Life Sciences/Institute of Agro-Bioengineering, Guizhou University, Guizhou Province, Guiyang, 550025, China
- Guizhou Province Key Laboratory of Agricultural and Animal Products Storage and Processing, School of Liquor and Food Engineering, Guizhou University, Guizhou, Guiyang, 550025, China
| | - Xueya Wang
- Chili Pepper Research Institute, Guizhou Provincial Academy of Agricultural Sciences, Guizhou, Guiyang, 550006, China
| | - Ying Zhou
- Guizhou Province Key Laboratory of Agricultural and Animal Products Storage and Processing, School of Liquor and Food Engineering, Guizhou University, Guizhou, Guiyang, 550025, China
| | - Qiujin Zhu
- Key Laboratory of Plant Resource Conservation and Germplasm Innovation in Mountainous Region (Ministry of Education), College of Life Sciences/Institute of Agro-Bioengineering, Guizhou University, Guizhou Province, Guiyang, 550025, China.
- Guizhou Province Key Laboratory of Agricultural and Animal Products Storage and Processing, School of Liquor and Food Engineering, Guizhou University, Guizhou, Guiyang, 550025, China.
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4
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Chi C, Xu R, Chen Q, Zhang X, Shi X, Jin H, Yin F, Jia H, Zhang L, Yang D, Ju J, Li Q, Ma M. Structural Insight into a Metal-Dependent Mutase Revealing an Arginine Residue-Covalently Mediated Interconversion between Nucleotide-Based Pyranose and Furanose. ACS Catal 2023. [DOI: 10.1021/acscatal.2c04907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Changbiao Chi
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, 38 Xueyuan Road, Haidian District, Beijing 100191, China
| | - Run Xu
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, RNAM Center for Marine Microbiology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, China
| | - Qianqian Chen
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, 38 Xueyuan Road, Haidian District, Beijing 100191, China
| | - Xiaohui Zhang
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, 38 Xueyuan Road, Haidian District, Beijing 100191, China
| | - Xiaomeng Shi
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, 38 Xueyuan Road, Haidian District, Beijing 100191, China
| | - Hongwei Jin
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, 38 Xueyuan Road, Haidian District, Beijing 100191, China
| | - Fuling Yin
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, 38 Xueyuan Road, Haidian District, Beijing 100191, China
| | - Hongli Jia
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, 38 Xueyuan Road, Haidian District, Beijing 100191, China
| | - Liangren Zhang
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, 38 Xueyuan Road, Haidian District, Beijing 100191, China
| | - Donghui Yang
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, 38 Xueyuan Road, Haidian District, Beijing 100191, China
| | - Jianhua Ju
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, RNAM Center for Marine Microbiology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, China
| | - Qinglian Li
- CAS Key Laboratory of Tropical Marine Bio-Resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, RNAM Center for Marine Microbiology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, China
| | - Ming Ma
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, 38 Xueyuan Road, Haidian District, Beijing 100191, China
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5
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Beaupre BA, Moran GR. N5 Is the New C4a: Biochemical Functionalization of Reduced Flavins at the N5 Position. Front Mol Biosci 2020; 7:598912. [PMID: 33195440 PMCID: PMC7662398 DOI: 10.3389/fmolb.2020.598912] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Accepted: 10/05/2020] [Indexed: 12/31/2022] Open
Abstract
For three decades the C4a-position of reduced flavins was the known site for covalency within flavoenzymes. The reactivity of this position of the reduced isoalloxazine ring with the dioxygen ground-state triplet established the C4a as a site capable of one-electron chemistry. Within the last two decades new types of reduced flavin reactivity have been documented. These studies reveal that the N5 position is also a protean site of reactivity, that is capable of nucleophilic attack to form covalent bonds with substrates. In addition, though the precise mechanism of dioxygen reactivity is yet to be definitively demonstrated, it is clear that the N5 position is directly involved in substrate oxygenation in some enzymes. In this review we document the lineage of discoveries that identified five unique modes of N5 reactivity that collectively illustrate the versatility of this position of the reduced isoalloxazine ring.
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Affiliation(s)
- Brett A Beaupre
- Department of Chemistry and Biochemistry, Loyola University Chicago, Chicago, IL, United States
| | - Graham R Moran
- Department of Chemistry and Biochemistry, Loyola University Chicago, Chicago, IL, United States
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6
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Comparative genome analysis and characterization of a MDR Klebsiella variicola. Genomics 2020; 112:3179-3190. [PMID: 32504650 DOI: 10.1016/j.ygeno.2020.06.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 05/17/2020] [Accepted: 06/02/2020] [Indexed: 12/12/2022]
Abstract
Klebsiella variicola is an emerging pathogen responsible for causing blood-stream infections, urinary and respiratory tract related diseases in humans. In this report, we describe the genome sequence data and phenotypic characterization of K. variicola strain KV093 isolated from India. Comparative genome sequence analysis revealed the presence of genes linked with virulence, iron acquisition and transport, type 1 and type 3 pili, secretion systems including the capsular gene cluster. The plant-associated genes such as nitrogen fixation, growth and defense mechanisms against oxidative stress were also identified. On performing antibiotic susceptibility testing, growth inhibition, and stress challenge assays it was observed that the drug resistant K. variicola KV093 exhibited cross resistance to various antibiotics, antiseptics, including disinfectants. This report highlights the arsenal of virulence and antibiotic resistance determinants in K. variicola KV093, an effort emphasizing the current pressing need for regular surveillance of K. variicola strains especially in India.
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7
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A bifunctional O-antigen polymerase structure reveals a new glycosyltransferase family. Nat Chem Biol 2020; 16:450-457. [DOI: 10.1038/s41589-020-0494-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 02/05/2020] [Indexed: 02/07/2023]
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8
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Kelly SD, Clarke BR, Ovchinnikova OG, Sweeney RP, Williamson ML, Lowary TL, Whitfield C. Klebsiella pneumoniae O1 and O2ac antigens provide prototypes for an unusual strategy for polysaccharide antigen diversification. J Biol Chem 2019; 294:10863-10876. [PMID: 31138653 DOI: 10.1074/jbc.ra119.008969] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2019] [Revised: 05/21/2019] [Indexed: 12/17/2022] Open
Abstract
A limited range of different structures is observed in O-antigenic polysaccharides (OPSs) from Klebsiella pneumoniae lipopolysaccharides. Among these, several are based on modifications of a conserved core element of serotype O2a OPS, which has a disaccharide repeat structure [→3)-α-d-Galp-(1→3)-β-d-Galf-(1→]. Here, we describe the enzymatic pathways for a highly unusual modification strategy involving the attachment of a second glycan repeat-unit structure to the nonreducing terminus of O2a. This occurs by the addition of the O1 [→3)-α-d-Galp-(1→3)-β-d-Galp-(1→] or O2c [→3)-β-d-GlcpNAc-(1→5)-β-d-Galf-(1→] antigens. The organization of the enzyme activities performing these modifications differs, with the enzyme WbbY possessing two glycosyltransferase catalytic sites solely responsible for O1 antigen polymerization and forming a complex with the O2a glycosyltransferase WbbM. In contrast, O2c polymerization requires glycosyltransferases WbmV and WbmW, which interact with one another but apparently not with WbbM. Using defined synthetic acceptors and site-directed mutants to assign the activities of the WbbY catalytic sites, we found that the C-terminal WbbY domain is a UDP-Galp-dependent GT-A galactosyltransferase adding β-(1→3)-linked d-Galp, whereas the WbbY N terminus includes a GT-B enzyme adding α-(1→3)-linked d-Galp These activities build the O1 antigen on a terminal Galp in the O2a domain. Using similar approaches, we identified WbmV as the UDP-GlcNAc transferase and noted that WbmW represents a UDP-Galf-dependent enzyme and that both are GT-A members. WbmVW polymerizes the O2c antigen on a terminal Galf. Our results provide mechanistic and conceptual insights into an important strategy for polysaccharide antigen diversification in bacteria.
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Affiliation(s)
- Steven D Kelly
- Department of Molecular and Cellular Biology, University of Guelph, Ontario N1G 2W1 and
| | - Bradley R Clarke
- Department of Molecular and Cellular Biology, University of Guelph, Ontario N1G 2W1 and
| | - Olga G Ovchinnikova
- Department of Molecular and Cellular Biology, University of Guelph, Ontario N1G 2W1 and
| | - Ryan P Sweeney
- Alberta Glycomics Centre and Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - Monica L Williamson
- Department of Molecular and Cellular Biology, University of Guelph, Ontario N1G 2W1 and
| | - Todd L Lowary
- Alberta Glycomics Centre and Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - Chris Whitfield
- Department of Molecular and Cellular Biology, University of Guelph, Ontario N1G 2W1 and.
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9
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Clarke BR, Ovchinnikova OG, Kelly SD, Williamson ML, Butler JE, Liu B, Wang L, Gou X, Follador R, Lowary TL, Whitfield C. Molecular basis for the structural diversity in serogroup O2-antigen polysaccharides in Klebsiella pneumoniae. J Biol Chem 2018; 293:4666-4679. [PMID: 29602878 DOI: 10.1074/jbc.ra117.000646] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Revised: 01/23/2018] [Indexed: 12/17/2022] Open
Abstract
Klebsiella pneumoniae is a major health threat. Vaccination and passive immunization are considered as alternative therapeutic strategies for managing Klebsiella infections. Lipopolysaccharide O antigens are attractive candidates because of the relatively small range of known O-antigen polysaccharide structures, but immunotherapeutic applications require a complete understanding of the structures found in clinical settings. Currently, the precise number of Klebsiella O antigens is unknown because available serological tests have limited resolution, and their association with defined chemical structures is sometimes uncertain. Molecular serotyping methods can evaluate clinical prevalence of O serotypes but require a full understanding of the genetic determinants for each O-antigen structure. This is problematic with Klebsiella pneumoniae because genes outside the main rfb (O-antigen biosynthesis) locus can have profound effects on the final structure. Here, we report two new loci encoding enzymes that modify a conserved polysaccharide backbone comprising disaccharide repeat units [→3)-α-d-Galp-(1→3)-β-d-Galf-(1→] (O2a antigen). We identified in serotype O2aeh a three-component system that modifies completed O2a glycan in the periplasm by adding 1,2-linked α-Galp side-group residues. In serotype O2ac, a polysaccharide comprising disaccharide repeat units [→5)-β-d-Galf-(1→3)-β-d-GlcpNAc-(1→] (O2c antigen) is attached to the non-reducing termini of O2a-antigen chains. O2c-polysaccharide synthesis is dependent on a locus encoding three glycosyltransferase enzymes. The authentic O2aeh and O2c antigens were recapitulated in recombinant Escherichia coli hosts to establish the essential gene set for their synthesis. These findings now provide a complete understanding of the molecular genetic basis for the known variations in Klebsiella O-antigen carbohydrate structures based on the O2a backbone.
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Affiliation(s)
- Bradley R Clarke
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
| | - Olga G Ovchinnikova
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
| | - Steven D Kelly
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
| | - Monica L Williamson
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
| | - Jennifer E Butler
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
| | - Bin Liu
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda St. TEDA, Tianjin 300457, China
| | - Lu Wang
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda St. TEDA, Tianjin 300457, China
| | - Xi Gou
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 23 Hongda St. TEDA, Tianjin 300457, China
| | | | - Todd L Lowary
- Department of Chemistry and Alberta Glycomics Centre, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - Chris Whitfield
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1.
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10
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Ivin M, Dumigan A, de Vasconcelos FN, Ebner F, Borroni M, Kavirayani A, Przybyszewska KN, Ingram RJ, Lienenklaus S, Kalinke U, Stoiber D, Bengoechea JA, Kovarik P. Natural killer cell-intrinsic type I IFN signaling controls Klebsiella pneumoniae growth during lung infection. PLoS Pathog 2017; 13:e1006696. [PMID: 29112952 PMCID: PMC5675380 DOI: 10.1371/journal.ppat.1006696] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2017] [Accepted: 10/16/2017] [Indexed: 12/20/2022] Open
Abstract
Klebsiella pneumoniae is a significant cause of nosocomial pneumonia and an alarming pathogen owing to the recent isolation of multidrug resistant strains. Understanding of immune responses orchestrating K. pneumoniae clearance by the host is of utmost importance. Here we show that type I interferon (IFN) signaling protects against lung infection with K. pneumoniae by launching bacterial growth-controlling interactions between alveolar macrophages and natural killer (NK) cells. Type I IFNs are important but disparate and incompletely understood regulators of defense against bacterial infections. Type I IFN receptor 1 (Ifnar1)-deficient mice infected with K. pneumoniae failed to activate NK cell-derived IFN-γ production. IFN-γ was required for bactericidal action and the production of the NK cell response-amplifying IL-12 and CXCL10 by alveolar macrophages. Bacterial clearance and NK cell IFN-γ were rescued in Ifnar1-deficient hosts by Ifnar1-proficient NK cells. Consistently, type I IFN signaling in myeloid cells including alveolar macrophages, monocytes and neutrophils was dispensable for host defense and IFN-γ activation. The failure of Ifnar1-deficient hosts to initiate a defense-promoting crosstalk between alveolar macrophages and NK cell was circumvented by administration of exogenous IFN-γ which restored endogenous IFN-γ production and restricted bacterial growth. These data identify NK cell-intrinsic type I IFN signaling as essential driver of K. pneumoniae clearance, and reveal specific targets for future therapeutic exploitations.
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Affiliation(s)
- Masa Ivin
- Max F. Perutz Laboratories, University of Vienna, Vienna Biocenter (VBC), Vienna, Austria
| | - Amy Dumigan
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, Belfast, United Kingdom
| | - Filipe N. de Vasconcelos
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, Belfast, United Kingdom
| | - Florian Ebner
- Max F. Perutz Laboratories, University of Vienna, Vienna Biocenter (VBC), Vienna, Austria
| | - Martina Borroni
- Max F. Perutz Laboratories, University of Vienna, Vienna Biocenter (VBC), Vienna, Austria
| | - Anoop Kavirayani
- Vienna Biocenter Core Facilities, Histopathology Facility, Dr. Bohr-Gasse 3, Vienna, Austria
| | - Kornelia N. Przybyszewska
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, Belfast, United Kingdom
| | - Rebecca J. Ingram
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, Belfast, United Kingdom
| | - Stefan Lienenklaus
- Institute for Experimental Infection Research, TWINCORE, Centre for Experimental and Clinical Infection Research, a joint venture between the Hannover Medical School and the Helmholtz Centre for Infection Research, Hannover, Germany
| | - Ulrich Kalinke
- Institute for Experimental Infection Research, TWINCORE, Centre for Experimental and Clinical Infection Research, a joint venture between the Hannover Medical School and the Helmholtz Centre for Infection Research, Hannover, Germany
| | - Dagmar Stoiber
- Institute of Pharmacology, Medical University of Vienna, Vienna, Austria
- Ludwig Boltzmann Institute for Cancer Research, Vienna, Austria
| | - Jose A. Bengoechea
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, Belfast, United Kingdom
| | - Pavel Kovarik
- Max F. Perutz Laboratories, University of Vienna, Vienna Biocenter (VBC), Vienna, Austria
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11
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Zamora CY, Schocker NS, Chang MM, Imperiali B. Chemoenzymatic Synthesis and Applications of Prokaryote-Specific UDP-Sugars. Methods Enzymol 2017; 597:145-186. [PMID: 28935101 DOI: 10.1016/bs.mie.2017.06.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
This method describes the chemoenzymatic synthesis of several nucleotide sugars, which are essential substrates in the biosynthesis of prokaryotic N- and O-linked glycoproteins. Protein glycosylation is now known to be widespread in prokaryotes and proceeds via sequential action of several enzymes, utilizing both common and modified prokaryote-specific sugar nucleotides. The latter, which include UDP-hexoses such as UDP-diNAc-bacillosamine (UDP-diNAcBac), UDP-diNAcAlt, and UDP-2,3-diNAcManA, are also important components of other bacterial and archaeal glycoconjugates. The ready availability of these "high-value" intermediates will enable courses of study into inhibitor screening, glycoconjugate biosynthesis pathway discovery, and unnatural carbohydrate incorporation toward metabolic engineering.
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Affiliation(s)
| | | | - Michelle M Chang
- Massachusetts Institute of Technology, Cambridge, MA, United States
| | - Barbara Imperiali
- Massachusetts Institute of Technology, Cambridge, MA, United States.
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12
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Kuttiyatveetil JRA, Sanders DAR. Analysis of plant UDP-arabinopyranose mutase (UAM): Role of divalent metals and structure prediction. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2017; 1865:510-519. [PMID: 28192204 DOI: 10.1016/j.bbapap.2017.02.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 09/24/2016] [Revised: 01/16/2017] [Accepted: 02/03/2017] [Indexed: 11/16/2022]
Abstract
UDP-arabinopyranose mutase (UAM) is a plant enzyme which interconverts UDP-arabinopyranose (UDP-Arap; a six-membered sugar) to UDP-arabinofuranose (UDP-Araf; a five-membered sugar). Plant mutases belong to a small gene family called Reversibly Glycosylated Proteins (RGPs). So far, UAM has been identified in Oryza sativa (Rice), Arabidopsis thaliana and Hordeum vulgare (Barley). The enzyme requires divalent metal ions for catalytic activity. Here, the divalent metal ion dependency of UAMs from O. sativa (rice) and A. thaliana have been studied using HPLC-based kinetic assays. It was determined that UAM from these species had the highest relative activity in a range of 40-80μM Mn2+. Excess Mn2+ ion concentration decreased the enzyme activity. This trend was observed when other divalent metal ions were used to test activity. To gain a perspective of the role played by the metal ion in activity, an ab initio structural model was generated based on the UAM amino acid sequence and a potential metal binding region was identified. Based on our results, we propose that the probable role of the metal in UAM is stabilizing the diphosphate of the substrate, UDP-Arap.
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Affiliation(s)
- Jijin R A Kuttiyatveetil
- Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, Saskatchewan, S7N 5C9, Canada
| | - David A R Sanders
- Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, Saskatchewan, S7N 5C9, Canada.
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13
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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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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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15
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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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16
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Tomás A, Lery L, Regueiro V, Pérez-Gutiérrez C, Martínez V, Moranta D, Llobet E, González-Nicolau M, Insua JL, Tomas JM, Sansonetti PJ, Tournebize R, Bengoechea JA. Functional Genomic Screen Identifies Klebsiella pneumoniae Factors Implicated in Blocking Nuclear Factor κB (NF-κB) Signaling. J Biol Chem 2015; 290:16678-97. [PMID: 25971969 PMCID: PMC4505419 DOI: 10.1074/jbc.m114.621292] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2014] [Indexed: 01/01/2023] Open
Abstract
Klebsiella pneumoniae is an etiologic agent of community-acquired and nosocomial pneumonia. It has been shown that K. pneumoniae infections are characterized by reduced early inflammatory response. Recently our group has shown that K. pneumoniae dampens the activation of inflammatory responses by antagonizing the activation of the NF-κB canonical pathway. Our results revealed that K. pneumoniae capsule polysaccharide (CPS) was necessary but not sufficient to attenuate inflammation. To identify additional Klebsiella factors required to dampen inflammation, we standardized and applied a high-throughput gain-of-function screen to examine a Klebsiella transposon mutant library. We identified 114 mutants that triggered the activation of NF-κB. Two gene ontology categories accounted for half of the loci identified in the screening: metabolism and transport genes (32% of the mutants) and envelope-related genes (17%). Characterization of the mutants revealed that the lack of the enterobactin siderophore was linked to a reduced CPS expression, which in turn underlined the NF-κB activation induced by the mutant. The lipopolysaccharide (LPS) O-polysaccharide and the pullulanase (PulA) type 2 secretion system (T2SS) are required for full effectiveness of the immune evasion. Importantly, these factors do not play a redundant role. The fact that LPS O-polysaccharide and T2SS mutant-induced responses were dependent on TLR2-TLR4-MyD88 activation suggested that LPS O-polysaccharide and PulA perturbed Toll-like receptor (TLR)-dependent recognition of K. pneumoniae. Finally, we demonstrate that LPS O-polysaccharide and pulA mutants are attenuated in the pneumonia mouse model. We propose that LPS O-polysaccharide and PulA T2SS could be new targets for the design of new antimicrobials. Increasing TLR-governed defense responses might provide also selective alternatives for the management of K. pneumoniae pneumonia.
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Affiliation(s)
- Anna Tomás
- From the Infection and Immunity Program, Fundación de Investigación Sanitaria de las Islas Baleares (FISIB), 07110 Mallorca, Spain, the Instituto de Investigación Sanitaria de Palma (IdisPa), 07120 Mallorca, Spain, the Centro de Investigación Biomédica en Red Enfermedades Respiratorias (CIBERES), 28029 Madrid, Spain
| | - Leticia Lery
- the Unité de Pathogénie Microbienne Moléculaire, Institut Pasteur, 75724 Paris, France, INSERM U786, 75724 Paris, France
| | - Verónica Regueiro
- From the Infection and Immunity Program, Fundación de Investigación Sanitaria de las Islas Baleares (FISIB), 07110 Mallorca, Spain, the Instituto de Investigación Sanitaria de Palma (IdisPa), 07120 Mallorca, Spain, the Centro de Investigación Biomédica en Red Enfermedades Respiratorias (CIBERES), 28029 Madrid, Spain
| | - Camino Pérez-Gutiérrez
- From the Infection and Immunity Program, Fundación de Investigación Sanitaria de las Islas Baleares (FISIB), 07110 Mallorca, Spain, the Instituto de Investigación Sanitaria de Palma (IdisPa), 07120 Mallorca, Spain, the Centro de Investigación Biomédica en Red Enfermedades Respiratorias (CIBERES), 28029 Madrid, Spain
| | - Verónica Martínez
- From the Infection and Immunity Program, Fundación de Investigación Sanitaria de las Islas Baleares (FISIB), 07110 Mallorca, Spain, the Instituto de Investigación Sanitaria de Palma (IdisPa), 07120 Mallorca, Spain, the Centro de Investigación Biomédica en Red Enfermedades Respiratorias (CIBERES), 28029 Madrid, Spain
| | - David Moranta
- From the Infection and Immunity Program, Fundación de Investigación Sanitaria de las Islas Baleares (FISIB), 07110 Mallorca, Spain, the Instituto de Investigación Sanitaria de Palma (IdisPa), 07120 Mallorca, Spain, the Centro de Investigación Biomédica en Red Enfermedades Respiratorias (CIBERES), 28029 Madrid, Spain
| | - Enrique Llobet
- From the Infection and Immunity Program, Fundación de Investigación Sanitaria de las Islas Baleares (FISIB), 07110 Mallorca, Spain, the Instituto de Investigación Sanitaria de Palma (IdisPa), 07120 Mallorca, Spain, the Centro de Investigación Biomédica en Red Enfermedades Respiratorias (CIBERES), 28029 Madrid, Spain
| | - Mar González-Nicolau
- From the Infection and Immunity Program, Fundación de Investigación Sanitaria de las Islas Baleares (FISIB), 07110 Mallorca, Spain, the Instituto de Investigación Sanitaria de Palma (IdisPa), 07120 Mallorca, Spain, the Centro de Investigación Biomédica en Red Enfermedades Respiratorias (CIBERES), 28029 Madrid, Spain
| | - Jose L Insua
- the Centre for Infection and Immunity, Queen's University Belfast, Belfast BT9 7AE, United Kingdom
| | - Juan M Tomas
- the Departamento de Microbiología, Facultad de Biología, Universidad de Barcelona, 08028 Barcelona, Spain
| | - Philippe J Sansonetti
- the Unité de Pathogénie Microbienne Moléculaire, Institut Pasteur, 75724 Paris, France, INSERM U786, 75724 Paris, France, Chaire de Microbiologie et Maladies Infectieuses, Collège de France, 75231 Paris, France
| | - Régis Tournebize
- the Unité de Pathogénie Microbienne Moléculaire, Institut Pasteur, 75724 Paris, France, INSERM U786, 75724 Paris, France, Imagopole, Plateforme d'Imagerie Dynamique, Institut Pasteur, 75724 Paris, France, and
| | - José A Bengoechea
- the Centre for Infection and Immunity, Queen's University Belfast, Belfast BT9 7AE, United Kingdom, the Consejo Superior de Investigaciones Científicas (CSIC), 28008 Madrid, Spain
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17
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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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18
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Differential single nucleotide polymorphism-based analysis of an outbreak caused by Salmonella enterica serovar Manhattan reveals epidemiological details missed by standard pulsed-field gel electrophoresis. J Clin Microbiol 2015; 53:1227-38. [PMID: 25653407 DOI: 10.1128/jcm.02930-14] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
We retrospectively analyzed a rare Salmonella enterica serovar Manhattan outbreak that occurred in Italy in 2009 to evaluate the potential of new genomic tools based on differential single nucleotide polymorphism (SNP) analysis in comparison with the gold standard genotyping method, pulsed-field gel electrophoresis. A total of 39 isolates were analyzed from patients (n=15) and food, feed, animal, and environmental sources (n=24), resulting in five different pulsed-field gel electrophoresis (PFGE) profiles. Isolates epidemiologically related to the outbreak clustered within the same pulsotype, SXB_BS.0003, without any further differentiation. Thirty-three isolates were considered for genomic analysis based on different sets of SNPs, core, synonymous, nonsynonymous, as well as SNPs in different codon positions, by Bayesian and maximum likelihood algorithms. Trees generated from core and nonsynonymous SNPs, as well as SNPs at the second and first plus second codon positions detailed four distinct groups of isolates within the outbreak pulsotype, discriminating outbreak-related isolates of human and food origins. Conversely, the trees derived from synonymous and third-codon-position SNPs clustered food and human isolates together, indicating that all outbreak-related isolates constituted a single clone, which was in line with the epidemiological evidence. Further experiments are in place to extend this approach within our regional enteropathogen surveillance system.
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19
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Variation in the OC locus of Acinetobacter baumannii genomes predicts extensive structural diversity in the lipooligosaccharide. PLoS One 2014; 9:e107833. [PMID: 25247305 PMCID: PMC4172580 DOI: 10.1371/journal.pone.0107833] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2013] [Accepted: 08/06/2014] [Indexed: 11/27/2022] Open
Abstract
Lipooligosaccharide (LOS) is a complex surface structure that is linked to many pathogenic properties of Acinetobacter baumannii. In A. baumannii, the genes responsible for the synthesis of the outer core (OC) component of the LOS are located between ilvE and aspS. The content of the OC locus is usually variable within a species, and examination of 6 complete and 227 draft A. baumannii genome sequences available in GenBank non-redundant and Whole Genome Shotgun databases revealed nine distinct new types, OCL4-OCL12, in addition to the three known ones. The twelve gene clusters fell into two distinct groups, designated Group A and Group B, based on similarities in the genes present. OCL6 (Group B) was unique in that it included genes for the synthesis of L-Rhamnosep. Genetic exchange of the different configurations between strains has occurred as some OC forms were found in several different sequence types (STs). OCL1 (Group A) was the most widely distributed being present in 18 STs, and OCL6 was found in 16 STs. Variation within clones was also observed, with more than one OC locus type found in the two globally disseminated clones, GC1 and GC2, that include the majority of multiply antibiotic resistant isolates. OCL1 was the most abundant gene cluster in both GC1 and GC2 genomes but GC1 isolates also carried OCL2, OCL3 or OCL5, and OCL3 was also present in GC2. As replacement of the OC locus in the major global clones indicates the presence of sub-lineages, a PCR typing scheme was developed to rapidly distinguish Group A and Group B types, and to distinguish the specific forms found in GC1 and GC2 isolates.
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20
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Chlubnová I, Králová B, Dvořáková H, Hošek P, Spiwok V, Filipp D, Nugier-Chauvin C, Daniellou R, Ferrières V. The versatile enzyme Araf51 allowed efficient synthesis of rare pathogen-related β-d-galactofuranosyl-pyranoside disaccharides. Org Biomol Chem 2014; 12:3080-9. [DOI: 10.1039/c3ob42519c] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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21
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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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22
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Marino C, Baldoni L. Synthesis of D-galactofuranose-containing molecules: design of galactofuranosyl acceptors. Chembiochem 2014; 15:188-204. [PMID: 24420700 DOI: 10.1002/cbic.201300638] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2013] [Indexed: 11/11/2022]
Abstract
D-Galactofuranose (D-Galf) is present in glycoconjugates of several pathogenic microorganisms but is absent in mammals, so it is a good target for the development of chemotherapeutic agents for the treatment of microbial infections. This fact has increased interest in the synthesis of D-Galf-containing molecules for corresponding glycobiological studies. The synthesis of oligosaccharides, glycoconjugates, and mimetics of D-Galf requires specific methods for the preparation of galactose derivatives in the furanosic configuration, the synthesis of appropriate acceptors, and efficient glycosylation methods for the construction of α- and β-D-Galf linkages. This review summarizes the different strategies developed for the preparation of partially protected derivatives of D-Galf, suitable as acceptors for the construction of (1→2), (1→3), (1→5), and (1→6) link- ages, and describes recent applications.
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Affiliation(s)
- Carla Marino
- CIHIDECAR-CONICET-UBA, 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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23
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Alteration of the exopolysaccharide production and the transcriptional profile of free-living Frankia strain CcI3 under nitrogen-fixing conditions. Appl Microbiol Biotechnol 2013; 97:10499-509. [PMID: 24097014 DOI: 10.1007/s00253-013-5277-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2013] [Revised: 09/09/2013] [Accepted: 09/10/2013] [Indexed: 10/26/2022]
Abstract
We investigated the effect of different nitrogen (N) sources on exopolysaccharide (EPS) production and composition by Frankia strain CcI3, a N2-fixing actinomycete that forms root nodules with Casuarina species. Frankia cells grown in the absence of NH4Cl (i.e., under N2-fixing conditions) produced 1.7-fold more EPS, with lower galactose (45.1 vs. 54.7 mol%) and higher mannose (17.3 vs. 9.7 mol%) contents than those grown in the presence of NH4Cl as a combined N-source. In the absence of the combined N-source, terminally linked and branched residue contents were nearly twice as high with 32.8 vs. 15.1 mol% and 15.1 vs. 8.7 mol%, respectively, than in its presence, while the content of linearly linked residues was lower with 52.1 mol% compared to 76.2 mol%. To find out clues for the altered EPS production at the transcriptional level, we performed whole-gene expression profiling using quantitative reverse transcription PCR and microarray technology. The transcription profiles of Frankia strain CcI3 grown in the absence of NH4Cl revealed up to 2 orders of magnitude higher transcription of nitrogen fixation-related genes compared to those of CcI3 cells grown in the presence of NH4Cl. Unexpectedly, microarray data did not provide evidence for transcriptional regulation as a mechanism for differences in EPS production. These findings indicate effects of nitrogen fixation on the production and composition of EPS in Frankia strain CcI3 and suggest posttranscriptional regulation of enhanced EPS production in the absence of the combined N-source.
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24
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Comparative genomics of closely related strains of Klebsiella pneumoniae reveals genes possibly involved in colistin resistance. ANN MICROBIOL 2013. [DOI: 10.1007/s13213-013-0727-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
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25
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Kizjakina K, Tanner JJ, Sobrado P. Targeting UDP-galactopyranose mutases from eukaryotic human pathogens. Curr Pharm Des 2013; 19:2561-73. [PMID: 23116395 PMCID: PMC3624792 DOI: 10.2174/1381612811319140007] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2012] [Accepted: 10/30/2012] [Indexed: 12/19/2022]
Abstract
UDP-Galactopyranose mutase (UGM) is a unique flavin-dependent enzyme that catalyzes the conversion of UDP-galactopyranose(UDP-Galp) to UDP-galactofuranose (UDP-Galf). The product of this reaction is the precursor to Galf, a major component of the cell wall and of cell surface glycoproteins and glycolipids in many eukaryotic and prokaryotic human pathogens. The function of UGM is important in the virulence of fungi, parasites, and bacteria. Its role in virulence and its absence in humans suggest that UGM is an ideal drug target. Significant structural and mechanistic information has been accumulated on the prokaryotic UGMs; however, in the past few years the research interest has shifted to UGMs from eukaryotic human pathogens such as fungi and protozoan parasites. It has become clear that UGMs from prokaryotic and eukaryotic organisms have different structural and mechanistic features. The amino acid sequence identity between these two classes of enzymes is low, resulting in differences in oligomeric states, substrate binding, active site flexibility, and interaction with redox partners. However, the unique role of the flavin cofactor in catalysis is conserved among this enzyme family. In this review, recent findings on eukaryotic UGMs are discussed and presented in comparison with prokaryotic UGMs.
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Affiliation(s)
- Karina Kizjakina
- Department of Biochemistry, Virginia Tech, Blacksburg, VA 24061, USA
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26
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Characterization of free exopolysaccharides secreted by Mycoplasma mycoides subsp. mycoides. PLoS One 2013; 8:e68373. [PMID: 23869216 PMCID: PMC3711806 DOI: 10.1371/journal.pone.0068373] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2013] [Accepted: 05/29/2013] [Indexed: 12/25/2022] Open
Abstract
Contagious bovine pleuropneumonia is a severe respiratory disease of cattle that is caused by a bacterium of the Mycoplasma genus, namely Mycoplasma mycoides subsp. mycoides (Mmm). In the absence of classical virulence determinants, the pathogenicity of Mmm is thought to rely on intrinsic metabolic functions and specific components of the outer cell surface. One of these latter, the capsular polysaccharide galactan has been notably demonstrated to play a role in Mmm persistence and dissemination. The free exopolysaccharides (EPS), also produced by Mmm and shown to circulate in the blood stream of infected cattle, have received little attention so far. Indeed, their characterization has been hindered by the presence of polysaccharide contaminants in the complex mycoplasma culture medium. In this study, we developed a method to produce large quantities of EPS by transfer of mycoplasma cells from their complex broth to a chemically defined medium and subsequent purification. NMR analyses revealed that the purified, free EPS had an identical β(1−>6)-galactofuranosyl structure to that of capsular galactan. We then analyzed intraclonal Mmm variants that produce opaque/translucent colonies on agar. First, we demonstrated that colony opacity was related to the production of a capsule, as observed by electron microscopy. We then compared the EPS extracts and showed that the non-capsulated, translucent colony variants produced higher amounts of free EPS than the capsulated, opaque colony variants. This phenotypic variation was associated with an antigenic variation of a specific glucose phosphotransferase permease. Finally, we conducted in silico analyses of candidate polysaccharide biosynthetic pathways in order to decipher the potential link between glucose phosphotransferase permease activity and attachment/release of galactan. The co-existence of variants producing alternative forms of galactan (capsular versus free extracellular galactan) and associated with an antigenic switch constitutes a finely tuned mechanism that may be involved in virulence.
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27
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Heiss C, Skowyra ML, Liu H, Klutts JS, Wang Z, Williams M, Srikanta D, Beverley SM, Azadi P, Doering TL. Unusual galactofuranose modification of a capsule polysaccharide in the pathogenic yeast Cryptococcus neoformans. J Biol Chem 2013; 288:10994-1003. [PMID: 23408430 DOI: 10.1074/jbc.m112.441998] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Galactofuranose (Galf) is the five-membered ring form of galactose. Although it is absent from mammalian glycans, it occurs as a structural and antigenic component of important cell surface molecules in a variety of microbes, ranging from bacteria to parasites and fungi. One such organism is Cryptococcus neoformans, a pathogenic yeast that causes lethal meningoencephalitis in immunocompromised individuals, particularly AIDS patients. C. neoformans is unique among fungal pathogens in bearing a complex polysaccharide capsule, a critical virulence factor reported to include Galf. Notably, how Galf modification contributes to the structure and function of the cryptococcal capsule is not known. We have determined that Galf is β1,2-linked to an unusual tetrasubstituted galactopyranose of the glucuronoxylomannogalactan (GXMGal) capsule polysaccharide. This discovery fills a longstanding gap in our understanding of a major polymer of the cryptococcal capsule. We also engineered a C. neoformans strain that lacks UDP-galactopyranose mutase; this enzyme forms UDP-Galf, the nucleotide sugar donor required for Galf addition. Mutase activity was required for the incorporation of Galf into glucuronoxylomannogalactan but was dispensable for vegetative growth, cell integrity, and virulence in a mouse model.
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Affiliation(s)
- Christian Heiss
- Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia 30602, USA
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28
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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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29
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Dhatwalia R, Singh H, Solano LM, Oppenheimer M, Robinson RM, Ellerbrock JF, Sobrado P, Tanner JJ. Identification of the NAD(P)H binding site of eukaryotic UDP-galactopyranose mutase. J Am Chem Soc 2012; 134:18132-8. [PMID: 23036087 PMCID: PMC3493617 DOI: 10.1021/ja308188z] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
UDP-galactopyranose mutase (UGM) plays an essential role in galactofuranose biosynthesis in microorganisms by catalyzing the conversion of UDP-galactopyranose to UDP-galactofuranose. The enzyme has gained attention recently as a promising target for the design of new antifungal, antitrypanosomal, and antileishmanial agents. Here we report the first crystal structure of UGM complexed with its redox partner NAD(P)H. Kinetic protein crystallography was used to obtain structures of oxidized Aspergillus fumigatus UGM (AfUGM) complexed with NADPH and NADH, as well as reduced AfUGM after dissociation of NADP(+). NAD(P)H binds with the nicotinamide near the FAD isoalloxazine and the ADP moiety extending toward the mobile 200s active site flap. The nicotinamide riboside binding site overlaps that of the substrate galactopyranose moiety, and thus NADPH and substrate binding are mutually exclusive. On the other hand, the pockets for the adenine of NADPH and uracil of the substrate are distinct and separated by only 6 Å, which raises the possibility of designing novel inhibitors that bind both sites. All 12 residues that contact NADP(H) are conserved among eukaryotic UGMs. Residues that form the AMP pocket are absent in bacterial UGMs, which suggests that eukaryotic and bacterial UGMs have different NADP(H) binding sites. The structures address the longstanding question of how UGM binds NAD(P)H and provide new opportunities for drug discovery.
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Affiliation(s)
- Richa Dhatwalia
- Department of Chemistry, University of Missouri-Columbia, Columbia, MO 65211, USA
| | - Harkewal Singh
- Department of Chemistry, University of Missouri-Columbia, Columbia, MO 65211, USA
| | - Luis M. Solano
- Department of Biology, Costa Rica Institute of Technology, Cartago, Costa Rica
| | | | | | | | - Pablo Sobrado
- Department of Biochemistry, Virginia Tech, Blacksburg, VA 24061, USA
| | - John J. Tanner
- Department of Chemistry, University of Missouri-Columbia, Columbia, MO 65211, USA
- Department of Biochemistry, University of Missouri-Columbia, Columbia, MO 65211, USA
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30
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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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31
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van Straaten KE, Routier FH, Sanders DAR. Towards the crystal structure elucidation of eukaryotic UDP-galactopyranose mutase. Acta Crystallogr Sect F Struct Biol Cryst Commun 2012; 68:455-9. [PMID: 22505419 PMCID: PMC3325819 DOI: 10.1107/s1744309112006914] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2011] [Accepted: 02/15/2012] [Indexed: 11/10/2022]
Abstract
UDP-galactopyranose mutase (UGM) catalyzes the interconversion of UDP-galactopyranose and UDP-galactofuranose. Eukaryotic UGMs from Aspergillus fumigatus and Leishmania major have been purified to homogeneity by means of Ni(2+)-affinity chromatography and crystallized. Eukaryotic UGM structure elucidation was not straightforward owing to high pseudo-symmetry, twinning and very low anomalous signal. Phasing to 2.8 Å resolution using SAD was successful for L. major UGM. However, the maps could only be improved by iterative density modification and manual model building. High pseudo-symmetry and twinning prevented correct space-group assignment and the completion of structure refinement. The structure of A. fumigatus UGM to 2.52 Å resolution was determined by molecular replacement using the incomplete 2.8 Å resolution L. major UGM model.
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Affiliation(s)
- Karin E. van Straaten
- Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, Saskatchewan S7N 5C9, Canada
| | - Francoise H. Routier
- Medizinische Hochschule Hannover, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany
| | - David A. R. Sanders
- Department of Chemistry, University of Saskatchewan, 110 Science Place, Saskatoon, Saskatchewan S7N 5C9, Canada
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32
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Hsieh PF, Lin TL, Yang FL, Wu MC, Pan YJ, Wu SH, Wang JT. Lipopolysaccharide O1 antigen contributes to the virulence in Klebsiella pneumoniae causing pyogenic liver abscess. PLoS One 2012; 7:e33155. [PMID: 22427976 PMCID: PMC3299736 DOI: 10.1371/journal.pone.0033155] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2011] [Accepted: 02/10/2012] [Indexed: 12/17/2022] Open
Abstract
Klebsiella pneumoniae is the common cause of a global emerging infectious disease, community-acquired pyogenic liver abscess (PLA). Capsular polysaccharide (CPS) and lipopolysaccharide (LPS) are critical for this microorganism's ability to spread through the blood and to cause sepsis. While CPS type K1 is an important virulence factor in K. pneumoniae causing PLA, the role of LPS in PLA is not clear. Here, we characterize the role of LPS O antigen in the pathogenesis of K. pneumoniae causing PLA. NTUH-K2044 is a LPS O1 clinical strain; the presence of the O antigen was shown via the presence of 1,3-galactan in the LPS, and of sequences that align with the wb gene cluster, known to produce O-antigen. Serologic analysis of K. pneumoniae clinical isolates demonstrated that the O1 serotype was more prevalent in PLA strains than that in non-tissue-invasive strains (38/42 vs. 9/32, P<0.0001). O1 serotype isolates had a higher frequency of serum resistance, and mutation of the O1 antigen changed serum resistance in K. pneumoniae. A PLA-causing strain of CPS capsular type K2 and LPS serotype O1 (i.e., O1:K2 PLA strain) deleted for the O1 synthesizing genes was profoundly attenuated in virulence, as demonstrated in separate mouse models of septicemia and liver abscess. Immunization of mice with the K2044 magA-mutant (K(1) (-) O(1)) against LPS O1 provided protection against infection with an O1:K2 PLA strain, but not against infection with an O1:K1 PLA strain. Our findings indicate that the O1 antigen of PLA-associated K. pneumoniae contributes to virulence by conveying resistance to serum killing, promoting bacterial dissemination to and colonization of internal organs after the onset of bacteremia, and could be a useful vaccine candidate against infection by an O1:K2 PLA strain.
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Affiliation(s)
- Pei-Fang Hsieh
- Department of Microbiology, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Tzu-Lung Lin
- Department of Microbiology, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Feng-Ling Yang
- The Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Meng-Chuan Wu
- Department of Microbiology, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Yi-Jiun Pan
- Department of Microbiology, National Taiwan University College of Medicine, Taipei, Taiwan
| | - Shih-Hsiung Wu
- The Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Jin-Town Wang
- Department of Microbiology, National Taiwan University College of Medicine, Taipei, Taiwan
- Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan
- * E-mail:
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33
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Greenfield LK, Whitfield C. Synthesis of lipopolysaccharide O-antigens by ABC transporter-dependent pathways. Carbohydr Res 2012; 356:12-24. [PMID: 22475157 DOI: 10.1016/j.carres.2012.02.027] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2012] [Revised: 02/23/2012] [Accepted: 02/24/2012] [Indexed: 01/10/2023]
Abstract
The O-polysaccharide (O-PS; O-antigen) of bacterial lipopolysaccharides is made up of repeating units of one or more sugar residues and displays remarkable structural diversity. Despite the structural variations, there are only three strategies for O-PS assembly. The ATP-binding cassette (ABC)-transporter-dependent mechanism of O-PS biosynthesis is widespread. The Escherichia coli O9a and Klebsiella pneumoniae O2a antigens provide prototypes, which are distinguished by the fine details that link glycan polymerization and chain termination at the cytoplasmic face of the inner membrane to its export via the ABC transporter. Here, we describe the current understanding of these processes. Since glycoconjugate assembly complexes that utilize an ABC transporter-dependent pathway are widespread among the bacterial kingdom, the models described here are expected to extend beyond O-PS biosynthesis systems.
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Affiliation(s)
- Laura K Greenfield
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada N1G 2W1
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34
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van Straaten KE, Routier FH, Sanders DAR. Structural insight into the unique substrate binding mechanism and flavin redox state of UDP-galactopyranose mutase from Aspergillus fumigatus. J Biol Chem 2012; 287:10780-90. [PMID: 22334662 PMCID: PMC3322874 DOI: 10.1074/jbc.m111.322974] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
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). As in prokaryotic UGMs, the flavin needs to be reduced for the enzyme to be active. Here we present the first eukaryotic UGM structures from Aspergillus fumigatus (AfUGM). The structures are of UGM alone, with the substrate UDP-Galp and with the inhibitor UDP. Additionally, we report the structures of AfUGM bound to substrate with oxidized and reduced flavin. These structures provide insight into substrate recognition and structural changes observed upon substrate binding involving the mobile loops and the critical arginine residues Arg-182 and Arg-327. Comparison with prokaryotic UGM reveals that despite low sequence identity with known prokaryotic UGMs the overall fold is largely conserved. Structural differences between prokaryotic UGM and AfUGM result from inserts in AfUGM. A notable difference from prokaryotic UGMs is that AfUGM contains a third flexible loop (loop III) above the si-face of the isoalloxazine ring that changes position depending on the redox state of the flavin cofactor. This loop flipping has not been observed in prokaryotic UGMs. In addition we have determined the crystals structures and steady-state kinetic constants of the reaction catalyzed by mutants R182K, R327K, R182A, and R327A. These results support our hypothesis that Arg-182 and Arg-327 play important roles in stabilizing the position of the diphosphates of the nucleotide sugar and help to facilitate the positioning of the galactose moiety for catalysis.
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Affiliation(s)
- Karin E van Straaten
- Department of Chemistry, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5C9, Canada
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35
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Karunan Partha S, Sadeghi-Khomami A, Cren S, Robinson RI, Woodward S, Slowski K, Berast L, Zheng B, Thomas NR, Sanders DAR. Identification of Novel Inhibitors of UDP-Galactopyranose Mutase by Structure-Based Virtual Screening. Mol Inform 2011; 30:873-83. [PMID: 27468107 DOI: 10.1002/minf.201100085] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2011] [Accepted: 07/25/2010] [Indexed: 11/08/2022]
Abstract
UDP-galactopyranose mutase (UGM) is a flavo-enzyme involved in the bacterial cell wall biosynthesis. UGM catalyzes the reversible isomerization of UDP-galactopyranose (UDP-Galp) to UDP-galactofuranose (UDP-Galf). UDP-Galf is the activated precursor of galactofuranose (Galf) residues that are essential components of the cell wall of certain pathogenic bacteria such as Klebsiella pneumoniae and Mycobacterium tuberculosis. Neither UGM nor Galf residues are found in humans, making Galf biosynthesis a potential drug target for developing antibacterial agents. We report the identification of novel inhibitors of UGM by in silico docking of the LeadQuest compound database against UGM from Escherichia coli. The 13 most promising inhibitors were then evaluated against K. pneumonia and M. tuberculosis UGMs by enzyme inhibition studies. Two inhibitors were identified with IC50 values of ∼1 µM and subsequently these compounds were docked into the recently solved X-ray structure of Deinococcus radiodurans UGM. The structure-activity relationships of the initial 13 compounds evaluated as inhibitors are discussed.
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Affiliation(s)
- Sarathy Karunan Partha
- Department of Chemistry, University of Saskatchewa, 110 Science Place, Saskatoon, SK, Canada S7N 5C9
| | - Ali Sadeghi-Khomami
- Centre for Biomolecular Sciences, School of Chemistry, The University of Nottingham, University Park, Nottingham, UK
| | - Sylvaine Cren
- Centre for Biomolecular Sciences, School of Chemistry, The University of Nottingham, University Park, Nottingham, UK
| | - Richard I Robinson
- Centre for Biomolecular Sciences, School of Chemistry, The University of Nottingham, University Park, Nottingham, UK
| | - Simon Woodward
- Centre for Biomolecular Sciences, School of Chemistry, The University of Nottingham, University Park, Nottingham, UK
| | - Kate Slowski
- Department of Chemistry, University of Saskatchewa, 110 Science Place, Saskatoon, SK, Canada S7N 5C9
| | - Lindsey Berast
- Department of Chemistry, University of Saskatchewa, 110 Science Place, Saskatoon, SK, Canada S7N 5C9
| | - Blake Zheng
- Department of Chemistry, University of Alberta, Edmonton, AB, Canada
| | - Neil R Thomas
- Centre for Biomolecular Sciences, School of Chemistry, The University of Nottingham, University Park, Nottingham, UK.
| | - David A R Sanders
- Department of Chemistry, University of Saskatchewa, 110 Science Place, Saskatoon, SK, Canada S7N 5C9.
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36
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Oppenheimer M, Valenciano AL, Sobrado P. Biosynthesis of galactofuranose in kinetoplastids: novel therapeutic targets for treating leishmaniasis and chagas' disease. Enzyme Res 2011; 2011:415976. [PMID: 21687654 PMCID: PMC3112513 DOI: 10.4061/2011/415976] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Revised: 03/02/2011] [Accepted: 03/14/2011] [Indexed: 12/14/2022] Open
Abstract
Cell surface proteins of parasites play a role in pathogenesis by modulating mammalian cell recognition and cell adhesion during infection. β-Galactofuranose (Galf) is an important component of glycoproteins and glycolipids found on the cell surface of Leishmania spp. and Trypanosoma cruzi. β-Galf-containing glycans have been shown to be important in parasite-cell interaction and protection against oxidative stress. Here, we discuss the role of β-Galf in pathogenesis and recent studies on the Galf-biosynthetic enzymes: UDP-galactose 4′ epimerase (GalE), UDP-galactopyranose mutase (UGM), and UDP-galactofuranosyl transferase (GalfT). The central role in Galf formation, its unique chemical mechanism, and the absence of a homologous enzyme in humans identify UGM as the most attractive drug target in the β-Galf-biosynthetic pathway in protozoan parasites.
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37
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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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38
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Leone MR, Lackner G, Silipo A, Lanzetta R, Molinaro A, Hertweck C. An unusual galactofuranose lipopolysaccharide that ensures the intracellular survival of toxin-producing bacteria in their fungal host. Angew Chem Int Ed Engl 2011; 49:7476-80. [PMID: 20718018 DOI: 10.1002/anie.201003301] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Affiliation(s)
- Maria R Leone
- Dipartimento di Chimica Organica e Biochimica, Università di Napoli Federico II, via Cintia 4, 80126 Napoli, Italy
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39
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Abstract
Complex glycoconjugates play critical roles in the biology of microorganisms. Despite the remarkable diversity in glycan structures and the bacteria that produce them, conserved themes are evident in the biosynthesis-export pathways. One of the primary pathways involves representatives of the ATP-binding cassette (ABC) transporter superfamily. These proteins are responsible for the export of a wide variety of cell surface oligo- and polysaccharides in both Gram-positive and Gram-negative bacteria. Recent investigations of the structure and function of ABC transporters involved in the export of lipopolysaccharide O antigens have revealed two fundamentally different strategies for coupling glycan polymerization to export. These mechanisms are distinguished by the presence (or absence) of characteristic nonreducing terminal modifications on the export substrates, which serve as chain termination and/or export signals, and by the presence (or absence) of a discrete substrate-binding domain in the nucleotide-binding domain polypeptide of the ABC transporter. A bioinformatic survey examining ABC exporters from known oligo- and polysaccharide biosynthesis loci identifies conserved nucleotide-binding domain protein families that correlate well with themes in the structures and assembly of glycans. The familial relationships among the ABC exporters generate hypotheses concerning the biosynthesis of structurally diverse oligo- and polysaccharides, which play important roles in the biology of bacteria with different lifestyles.
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40
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Leone MR, Lackner G, Silipo A, Lanzetta R, Molinaro A, Hertweck C. An Unusual Galactofuranose Lipopolysaccharide That Ensures the Intracellular Survival of Toxin-Producing Bacteria in Their Fungal Host. Angew Chem Int Ed Engl 2010. [DOI: 10.1002/ange.201003301] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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41
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Perepelov AV, Dan Li, Bin Liu, Senchenkova SN, Dan Guo, Shashkov AS, Lu Feng, Knirel YA, Lei Wang. Structural and genetic characterization of the closely related O-antigens of Escherichia coli O85 and Salmonella enterica O17. Innate Immun 2010; 17:164-73. [DOI: 10.1177/1753425910369270] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
O-Antigen is a part of the lipopolysaccharide present in the outer membrane of Gram-negative bacteria, which confers major antigenic variability to the cell surface. In this study, we report on a previously undefined pair of Escherichia coli and Salmonella enterica with closely related O-antigens. The O-polysaccharides were isolated from the lipopolysaccharides of E. coli O85 and S. enterica O17 by mild acid degradation and studied by sugar analysis and NMR spectroscopy. The following structure was established for the O-unit of the E. coli O85-polysaccharide: The S. enterica O17-polysaccharide has the same carbohydrate backbone and, in addition, contains an O-acetyl group at position 2 of ~80% β-Galf residues. The O-antigen gene cluster of E. coli O85 was found to be closely related to that of S. enterica O17. Screening of type strains of all E. coli and S. enterica O-serogroups revealed two genes specific to the E. coli O85 O-antigen gene cluster, which can be used for development of PCR-based assays for identification and detection of E. coli O85 strains.
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Affiliation(s)
- Andrei V. Perepelov
- N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russian Federation,
| | - Dan Li
- TEDA School of Biological Sciences and Biotechnology, Nankai University, Tianjin, P. R. China, Tianjin Key Laboratory of Microbial Functional Genomics, Tianjin, P. R. China
| | - Bin Liu
- TEDA School of Biological Sciences and Biotechnology, Nankai University, Tianjin, P. R. China, Tianjin Key Laboratory of Microbial Functional Genomics, Tianjin, P. R. China
| | - Sof'ya N. Senchenkova
- N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russian Federation
| | - Dan Guo
- TEDA School of Biological Sciences and Biotechnology, Nankai University, Tianjin, P. R. China, Tianjin Key Laboratory of Microbial Functional Genomics, Tianjin, P. R. China
| | - Alexander S. Shashkov
- N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russian Federation
| | - Lu Feng
- TEDA School of Biological Sciences and Biotechnology, Nankai University, Tianjin, P. R. China, Tianjin Key Laboratory of Microbial Functional Genomics, Tianjin, P. R. China, Tianjin Research Center for Functional Genomics and Biochip, Tianjin, P. R. China
| | - Yuriy A. Knirel
- N.D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow, Russian Federation
| | - Lei Wang
- TEDA School of Biological Sciences and Biotechnology, Nankai University, Tianjin, P. R. China, Tianjin Key Laboratory of Microbial Functional Genomics, Tianjin, P. R. China, Tianjin Research Center for Functional Genomics and Biochip, Tianjin, P. R. China, The Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, P. R. China
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42
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Kos V, Whitfield C. A membrane-located glycosyltransferase complex required for biosynthesis of the D-galactan I lipopolysaccharide O antigen in Klebsiella pneumoniae. J Biol Chem 2010; 285:19668-87. [PMID: 20410291 DOI: 10.1074/jbc.m110.122598] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
D-galactan I is a polysaccharide with the disaccharide repeat unit structure [-->3-beta-D-Galf-(1-->3)-alpha-D-Galp-(1-->]. This glycan represents the lipopolysaccharide O antigen found in many Gram-negative bacteria, including several Klebsiella pneumoniae O serotypes. The polysaccharide is synthesized in the cytoplasm prior to its export via an ATP-binding cassette transporter. Sequence analysis predicts three galactosyltransferases in the D-galactan I genetic locus. They are WbbO (belonging to glycosyltransferase (GT) family 4), WbbM (GT-family 8), and WbbN (GT-family 2). The WbbO and WbbM proteins are each predicted to contain two domains, with the GT modules located toward their C termini. The N-terminal domains of WbbO and WbbM exhibit no similarity to proteins with known function. In vivo complementation assays suggest that all three glycosyltransferases are required for D-galactan I biosynthesis. Using a bacterial two-hybrid system and confirmatory co-purification strategies, evidence is provided for protein-protein interactions among the glycosyltransferases, creating a membrane-located enzyme complex dedicated to d-galactan I biosynthesis.
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Affiliation(s)
- Veronica Kos
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
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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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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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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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Novelli JF, Chaudhary K, Canovas J, Benner JS, Madinger CL, Kelly P, Hodgkin J, Carlow CKS. Characterization of the Caenorhabditis elegans UDP-galactopyranose mutase homolog glf-1 reveals an essential role for galactofuranose metabolism in nematode surface coat synthesis. Dev Biol 2009; 335:340-55. [PMID: 19751718 DOI: 10.1016/j.ydbio.2009.09.010] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2009] [Revised: 08/15/2009] [Accepted: 09/07/2009] [Indexed: 01/08/2023]
Abstract
Galactofuranose (Gal(f)), the furanoic form of d-galactose produced by UDP-galactopyranose mutases (UGMs), is present in surface glycans of some prokaryotes and lower eukaryotes. Absence of the Gal(f) biosynthetic pathway in vertebrates and its importance in several pathogens make UGMs attractive drug targets. Since the existence of Gal(f) in nematodes has not been established, we investigated the role of the Caenorhabditis elegans UGM homolog glf-1 in worm development. glf-1 mutants display significant late embryonic and larval lethality, and other phenotypes indicative of defective surface coat synthesis, the glycan-rich outermost layer of the nematode cuticle. The glf homolog from the protozoan Leishmania major partially complements C. elegans glf-1. glf-1 mutants rescued by L. major glf, which behave as glf-1 hypomorphs, display resistance to infection by Microbacterium nematophilum, a pathogen of rhabditid nematodes thought to bind to surface coat glycans. To confirm the presence of Gal(f) in C. elegans, we analyzed C. elegans nucleotide sugar pools using online electrospray ionization-mass spectrometry (ESI-MS). UDP-Gal(f) was detected in wild-type animals while absent in glf-1 deletion mutants. Our data indicate that Gal(f) likely has a pivotal role in maintenance of surface integrity in nematodes, supporting investigation of UGM as a drug target in parasitic species.
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Lamarre C, Beau R, Balloy V, Fontaine T, Wong Sak Hoi J, Guadagnini S, Berkova N, Chignard M, Beauvais A, Latgé JP. Galactofuranose attenuates cellular adhesion of Aspergillus fumigatus. Cell Microbiol 2009; 11:1612-23. [PMID: 19563461 DOI: 10.1111/j.1462-5822.2009.01352.x] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Galactofuranose (Galf) is a major molecule found in cell wall polysaccharides, secreted glycoproteins, membrane lipophosphoglycans and sphingolipids of Aspergillus fumigatus. The initial step in the Galf synthetic pathway is the re-arrangement of UDP-galactopyranose to UDP-Galf through the action of UDP-galactopyranose mutase. A mutant lacking the AfUGM1 gene encoding the UDP-galactopyranose mutase has been constructed. In the mutant, though there is a moderate reduction in the mycelial growth associated with an increased branching, it remains as pathogenic and as resistant to cell wall inhibitors and phagocytes as the wild-type parental strain. The major phenotype seen is a modification of the cell wall surface that results in an increase in adhesion of the mutants to different inert surfaces (glass and plastic) and epithelial respiratory cells. The adhesive phenotype is due to the unmasking of the mannan consecutive to the removal of galactofuran by the ugm1 mutation. Removal of the mannan layer from the mutant surface by a mannosidase treatment abolishes mycelial adhesion to surfaces.
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Affiliation(s)
- Claude Lamarre
- Unité des Aspergillus, Institut Pasteur, 25 rue du Docteur Roux, 75724 Paris Cedex 15, France
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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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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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