1
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Kelly SD, Ovchinnikova OG, Müller F, Steffen M, Braun M, Sweeney RP, Kowarik M, Follador R, Lowary TL, Serventi F, Whitfield C. Identification of a second glycoform of the clinically prevalent O1 antigen from Klebsiella pneumoniae. Proc Natl Acad Sci U S A 2023; 120:e2301302120. [PMID: 37428935 PMCID: PMC10629545 DOI: 10.1073/pnas.2301302120] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2023] [Accepted: 05/15/2023] [Indexed: 07/12/2023] Open
Abstract
Carbapenemase and extended β-lactamase-producing Klebsiella pneumoniae isolates represent a major health threat, stimulating increasing interest in immunotherapeutic approaches for combating Klebsiella infections. Lipopolysaccharide O antigen polysaccharides offer viable targets for immunotherapeutic development, and several studies have described protection with O-specific antibodies in animal models of infection. O1 antigen is produced by almost half of clinical Klebsiella isolates. The O1 polysaccharide backbone structure is known, but monoclonal antibodies raised against the O1 antigen showed varying reactivity against different isolates that could not be explained by the known structure. Reinvestigation of the structure by NMR spectroscopy revealed the presence of the reported polysaccharide backbone (glycoform O1a), as well as a previously unknown O1b glycoform composed of the O1a backbone modified with a terminal pyruvate group. The activity of the responsible pyruvyltransferase (WbbZ) was confirmed by western immunoblotting and in vitro chemoenzymatic synthesis of the O1b terminus. Bioinformatic data indicate that almost all O1 isolates possess genes required to produce both glycoforms. We describe the presence of O1ab-biosynthesis genes in other bacterial species and report a functional O1 locus on a bacteriophage genome. Homologs of wbbZ are widespread in genetic loci for the assembly of unrelated glycostructures in bacteria and yeast. In K. pneumoniae, simultaneous production of both O1 glycoforms is enabled by the lack of specificity of the ABC transporter that exports the nascent glycan, and the data reported here provide mechanistic understanding of the capacity for evolution of antigenic diversity within an important class of biomolecules produced by many bacteria.
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Affiliation(s)
- Steven D. Kelly
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ONN1G 2W1, Canada
| | - Olga G. Ovchinnikova
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ONN1G 2W1, Canada
| | | | | | - Martin Braun
- LimmaTech Biologics AG, Schlieren8952, Switzerland
| | - Ryan P. Sweeney
- Department of Chemistry, University of Alberta, Edmonton, ABT6G 2G2, Canada
| | | | | | - Todd L. Lowary
- Department of Chemistry, University of Alberta, Edmonton, ABT6G 2G2, Canada
- Institute of Biological Chemistry, Academia Sinica, Taipei, Nangang11529, Taiwan
- Institute of Biochemical Sciences, National Taiwan University, Taipei10617, Taiwan
| | | | - Chris Whitfield
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, ONN1G 2W1, Canada
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2
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Stephens Z, Wilson LFL, Zimmer J. Diverse mechanisms of polysaccharide biosynthesis, assembly and secretion across kingdoms. Curr Opin Struct Biol 2023; 79:102564. [PMID: 36870276 DOI: 10.1016/j.sbi.2023.102564] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Revised: 01/16/2023] [Accepted: 01/28/2023] [Indexed: 03/06/2023]
Abstract
Polysaccharides are essential biopolymers produced in all kingdoms of life. On the cell surface, they represent versatile architectural components, forming protective capsules and coats, cell walls, or adhesives. Extracellular polysaccharide (EPS) biosynthesis mechanisms differ based on the cellular localization of polymer assembly. Some polysaccharides are first synthesized in the cytosol and then extruded by ATP powered transporters [1]. In other cases, the polymers are assembled outside the cell [2], synthesized and secreted in a single step [3], or deposited on the cell surface via vesicular trafficking [4]. This review focuses on recent insights into the biosynthesis, secretion, and assembly of EPS in microbes, plants and vertebrates. We focus on comparing the sites of biosynthesis, secretion mechanisms, and higher-order EPS assemblies.
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Affiliation(s)
- Zachery Stephens
- Howard Hughes Medical Institute, University of Virginia School of Medicine, Charlottesville, VA, USA; Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, 480 Ray C. Hunt Dr., Charlottesville, VA 22908, USA
| | - Louis F L Wilson
- Howard Hughes Medical Institute, University of Virginia School of Medicine, Charlottesville, VA, USA; Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, 480 Ray C. Hunt Dr., Charlottesville, VA 22908, USA
| | - Jochen Zimmer
- Howard Hughes Medical Institute, University of Virginia School of Medicine, Charlottesville, VA, USA; Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, 480 Ray C. Hunt Dr., Charlottesville, VA 22908, USA.
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3
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Abstract
Glycans, carbohydrate molecules in the realm of biology, are present as biomedically important glycoconjugates and a characteristic aspect is that their structures in many instances are branched. In determining the primary structure of a glycan, the sugar components including the absolute configuration and ring form, anomeric configuration, linkage(s), sequence, and substituents should be elucidated. Solution state NMR spectroscopy offers a unique opportunity to resolve all these aspects at atomic resolution. During the last two decades, advancement of both NMR experiments and spectrometer hardware have made it possible to unravel carbohydrate structure more efficiently. These developments applicable to glycans include, inter alia, NMR experiments that reduce spectral overlap, use selective excitations, record tilted projections of multidimensional spectra, acquire spectra by multiple receivers, utilize polarization by fast-pulsing techniques, concatenate pulse-sequence modules to acquire several spectra in a single measurement, acquire pure shift correlated spectra devoid of scalar couplings, employ stable isotope labeling to efficiently obtain homo- and/or heteronuclear correlations, as well as those that rely on dipolar cross-correlated interactions for sequential information. Refined computer programs for NMR spin simulation and chemical shift prediction aid the structural elucidation of glycans, which are notorious for their limited spectral dispersion. Hardware developments include cryogenically cold probes and dynamic nuclear polarization techniques, both resulting in enhanced sensitivity as well as ultrahigh field NMR spectrometers with a 1H NMR resonance frequency higher than 1 GHz, thus improving resolution of resonances. Taken together, the developments have made and will in the future make it possible to elucidate carbohydrate structure in great detail, thereby forming the basis for understanding of how glycans interact with other molecules.
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Affiliation(s)
- Carolina Fontana
- Departamento
de Química del Litoral, CENUR Litoral Norte, Universidad de la República, Paysandú 60000, Uruguay
| | - Göran Widmalm
- Department
of Organic Chemistry, Arrhenius Laboratory, Stockholm University, S-106 91 Stockholm, Sweden,
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4
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Mann E, Kimber MS, Whitfield C. Bioinformatics analysis of diversity in bacterial glycan chain-termination chemistry and organization of carbohydrate-binding modules linked to ABC transporters. Glycobiology 2020; 29:822-838. [PMID: 31504498 DOI: 10.1093/glycob/cwz066] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2019] [Revised: 08/19/2019] [Accepted: 08/19/2019] [Indexed: 12/22/2022] Open
Abstract
The structures of bacterial cell surface glycans are remarkably diverse. In spite of this diversity, the general strategies used for their assembly are limited. In one of the major processes, found in both Gram-positive and Gram-negative bacteria, the glycan is polymerized in the cytoplasm on a polyprenol lipid carrier and exported from the cytoplasm by an ATP-binding cassette (ABC) transporter. The ABC transporter actively participates in determining the chain length of the glycan substrate, which impacts functional properties of the glycoconjugate products. A subset of these systems employs an additional elaborate glycan capping strategy that dictates the size distribution of the products. The hallmarks of prototypical capped glycan systems are a chain-terminating enzyme possessing a coiled-coil molecular ruler and an ABC transporter possessing a carbohydrate-binding module, which recognizes the glycan cap. To date, detailed investigations are limited to a small number of prototypes, and here, we used our current understanding of these processes for a bioinformatics census of other examples in available genome sequences. This study not only revealed additional instances of existing terminators but also predicted new chemistries as well as systems that diverge from the established prototypes. These analyses enable some new functional hypotheses and offer a roadmap for future research.
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Affiliation(s)
- Evan Mann
- Department of Molecular and Cellular Biology, University of Guelph, 50 Stone Rd. East, Guelph, Ontario N1G 2W1, Canada
| | - Matthew S Kimber
- Department of Molecular and Cellular Biology, University of Guelph, 50 Stone Rd. East, Guelph, Ontario N1G 2W1, Canada
| | - Chris Whitfield
- Department of Molecular and Cellular Biology, University of Guelph, 50 Stone Rd. East, Guelph, Ontario N1G 2W1, Canada
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5
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Kokoulin M, Lizanov IN, Romanenko LA, Chikalovets IV. Structure of phosphorylated and sulfated polysaccharides from lipopolysaccharide of marine bacterium Marinicella litoralis KMM 3900T. Carbohydr Res 2020; 490:107961. [DOI: 10.1016/j.carres.2020.107961] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2020] [Revised: 02/11/2020] [Accepted: 02/20/2020] [Indexed: 10/24/2022]
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6
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Mann E, Kelly SD, Al-Abdul-Wahid MS, Clarke BR, Ovchinnikova OG, Liu B, Whitfield C. Substrate recognition by a carbohydrate-binding module in the prototypical ABC transporter for lipopolysaccharide O-antigen from Escherichia coli O9a. J Biol Chem 2019; 294:14978-14990. [PMID: 31416837 DOI: 10.1074/jbc.ra119.010323] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 08/14/2019] [Indexed: 11/06/2022] Open
Abstract
Escherichia coli serotype O9a provides a model for export of lipopolysaccharide (LPS) O-antigen polysaccharide (O-PS) via ABC transporters. In O9a biosynthesis, a chain-terminator enzyme, WbdD, caps the nonreducing end of the glycan with a methylphosphate moiety and thereby establishes chain-length distribution. A carbohydrate-binding module (CBM) in the ABC transporter recognizes terminated glycans, ensuring that only mature O-PS is exported and incorporated into LPS. Here, we addressed two questions arising from this model. Are both residues in the binary terminator necessary for termination and export? And is a terminal methylphosphate moiety sufficient for export of heterologous glycans? To answer the first question, we uncoupled WbdD kinase and methyltransferase activities. WbdD mutants revealed that although the kinase activity is solely responsible for chain-length regulation, both activities are essential for CBM recognition and export. Consistent with this observation, a saturation transfer difference NMR experiment revealed a direct interaction between the CBM and the terminal methyl group. To determine whether methylphosphate is the sole determinant of substrate recognition by the CBM, we exploited Klebsiella pneumoniae O7, whose O-PS repeat-unit structure differs from O9a, but, as shown here, offers the second confirmed example of a terminal methylphosphate serving in substrate recognition. In vitro and in vivo experiments indicated that each CBM can bind the O-PS only with the native repeat unit, revealing that methylphosphate is essential but not sufficient for substrate recognition and export. Our findings provide important new insight into the structural determinants in a prototypical quality control system for glycan assembly and export.
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Affiliation(s)
- Evan Mann
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Steven D Kelly
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | | | - Bradley R Clarke
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Olga G Ovchinnikova
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Bin Liu
- TEDA Institute of Biological Sciences and Biotechnology, Nankai University, 3 Hongda St. TEDA, Tianjin 300457, China
| | - Chris Whitfield
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
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7
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Caffalette CA, Corey RA, Sansom MSP, Stansfeld PJ, Zimmer J. A lipid gating mechanism for the channel-forming O antigen ABC transporter. Nat Commun 2019; 10:824. [PMID: 30778065 PMCID: PMC6379404 DOI: 10.1038/s41467-019-08646-8] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2018] [Accepted: 01/23/2019] [Indexed: 12/15/2022] Open
Abstract
Extracellular glycan biosynthesis is a widespread microbial protection mechanism. In Gram-negative bacteria, the O antigen polysaccharide represents the variable region of outer membrane lipopolysaccharides. Fully assembled lipid-linked O antigens are translocated across the inner membrane by the WzmWzt ABC transporter for ligation to the lipopolysaccharide core, with the transporter forming a continuous transmembrane channel in a nucleotide-free state. Here, we report its structure in an ATP-bound conformation. Large structural changes within the nucleotide-binding and transmembrane regions push conserved hydrophobic residues at the substrate entry site towards the periplasm and provide a model for polysaccharide translocation. With ATP bound, the transporter forms a large transmembrane channel with openings toward the membrane and periplasm. The channel's periplasmic exit is sealed by detergent molecules that block solvent permeation. Molecular dynamics simulation data suggest that, in a biological membrane, lipid molecules occupy this periplasmic exit and prevent water flux in the transporter's resting state.
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Affiliation(s)
- Christopher A Caffalette
- Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
| | - Robin A Corey
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
| | - Mark S P Sansom
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
| | | | - Jochen Zimmer
- Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA.
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8
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Discovery of monoclonal antibodies cross-reactive to novel subserotypes of K. pneumoniae O3. Sci Rep 2017; 7:6635. [PMID: 28747785 PMCID: PMC5529442 DOI: 10.1038/s41598-017-06682-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2017] [Accepted: 06/16/2017] [Indexed: 01/15/2023] Open
Abstract
Klebsiella pneumoniae is responsible for nosocomial infections causing significant morbidity and mortality. Treatment of newly emerging multi-drug resistant strains is hampered due to severely limited antibiotic choices. Passive immunization targeting LPS O-antigens has been proposed as an alternative therapeutic option, given the limited variability of Klebsiella O-antigens. Here we report that the O3 serogroup, previously considered to have uniform O-antigen built of mannan, represents three different subtypes differing in the number of mannose residues within the O-antigen repeating units. Genetic analysis of the genes encoding mannose polymerization revealed differences that underline the observed structural alterations. The O3 variants represent antigenically different types based on the different reactivity pattern of murine monoclonal antibodies raised against a K. pneumoniae O3 strain. Typing of a collection of K. pneumoniae O3 clinical isolates showed that strains expressing the novel O3b antigen, the tri-mannose form, were more prevalent than those having the penta-mannose form, traditionally called O3, while the tetra-mannose variant, termed here O3a, seems to be rare. A monoclonal antibody cross-reacting with all three O3 sub-serogroups was also selected and shown to bind to the surface of various K. pneumoniae strains expressing different O3 subtypes and capsular antigens.
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9
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Wittmann A, Lamprinaki D, Bowles KM, Katzenellenbogen E, Knirel YA, Whitfield C, Nishimura T, Matsumoto N, Yamamoto K, Iwakura Y, Saijo S, Kawasaki N. Dectin-2 Recognizes Mannosylated O-antigens of Human Opportunistic Pathogens and Augments Lipopolysaccharide Activation of Myeloid Cells. J Biol Chem 2016; 291:17629-38. [PMID: 27358401 PMCID: PMC5016159 DOI: 10.1074/jbc.m116.741256] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Indexed: 12/20/2022] Open
Abstract
LPS consists of a relatively conserved region of lipid A and core oligosaccharide and a highly variable region of O-antigen polysaccharide. Whereas lipid A is known to bind to the Toll-like receptor 4 (TLR4)-myeloid differentiation factor 2 (MD2) complex, the role of the O-antigen remains unclear. Here we report a novel molecular interaction between dendritic cell-associated C-type lectin-2 (Dectin-2) and mannosylated O-antigen found in a human opportunistic pathogen, Hafnia alvei PCM 1223, which has a repeating unit of [-Man-α1,3-Man-α1,2-Man-α1,2-Man-α1,2-Man-α1,3-]. H. alvei LPS induced higher levels of TNFα and IL-10 from mouse bone marrow-derived dendritic cells (BM-DCs), when compared with Salmonella enterica O66 LPS, which has a repeat of [-Gal-α1,6-Gal-α1,4-[Glc-β1,3]GalNAc-α1,3-GalNAc-β1,3-]. In a cell-based reporter assay, Dectin-2 was shown to recognize H. alvei LPS. This binding was inhibited by mannosidase treatment of H. alvei LPS and by mutations in the carbohydrate-binding domain of Dectin-2, demonstrating that H. alvei LPS is a novel glycan ligand of Dectin-2. The enhanced cytokine production by H. alvei LPS was Dectin-2-dependent, because Dectin-2 knock-out BM-DCs failed to do so. This receptor cross-talk between Dectin-2 and TLR4 involved events including spleen tyrosine kinase (Syk) activation and receptor juxtaposition. Furthermore, another mannosylated LPS from Escherichia coli O9a also bound to Dectin-2 and augmented TLR4 activation of BM-DCs. Taken together, these data indicate that mannosylated O-antigens from several Gram-negative bacteria augment TLR4 responses through interaction with Dectin-2.
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Affiliation(s)
- Alexandra Wittmann
- From the Food and Health Institute Strategic Programme, Institute of Food Research, Norwich NR4 7UA, United Kingdom
| | - Dimitra Lamprinaki
- From the Food and Health Institute Strategic Programme, Institute of Food Research, Norwich NR4 7UA, United Kingdom
| | - Kristian M Bowles
- Norwich Medical School, University of East Anglia, Norwich NR4 7TJ, United Kingdom
| | - Ewa Katzenellenbogen
- the Ludwik Hirszfeld Institute of Immunology and Experimental Therapy, Wroclaw 53-114, Poland
| | - Yuriy A Knirel
- the N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow 119991, Russia
| | - Chris Whitfield
- the Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Takashi Nishimura
- the Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Chiba 277-8562, Japan
| | - Naoki Matsumoto
- the Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Chiba 277-8562, Japan
| | - Kazuo Yamamoto
- the Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Chiba 277-8562, Japan
| | - Yoichiro Iwakura
- the Center for Animal Disease Models, Research Institute for Biomedical Sciences, Tokyo University of Science, Chiba 278-0022, Japan, and
| | - Shinobu Saijo
- the Department of Molecular Immunology, Medical Mycology Research Center, Chiba University, Chiba 260-8673, Japan
| | - Norihito Kawasaki
- From the Food and Health Institute Strategic Programme, Institute of Food Research, Norwich NR4 7UA, United Kingdom, the Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Chiba 277-8562, Japan,
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10
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Hagelueken G, Clarke BR, Huang H, Tuukkanen A, Danciu I, Svergun DI, Hussain R, Liu H, Whitfield C, Naismith JH. A coiled-coil domain acts as a molecular ruler to regulate O-antigen chain length in lipopolysaccharide. Nat Struct Mol Biol 2015; 22:50-56. [PMID: 25504321 PMCID: PMC4650267 DOI: 10.1038/nsmb.2935] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2014] [Accepted: 11/20/2014] [Indexed: 11/22/2022]
Abstract
Long-chain bacterial polysaccharides have important roles in pathogenicity. In Escherichia coli O9a, a model for ABC transporter-dependent polysaccharide assembly, a large extracellular carbohydrate with a narrow size distribution is polymerized from monosaccharides by a complex of two proteins, WbdA (polymerase) and WbdD (terminating protein). Combining crystallography and small-angle X-ray scattering, we found that the C-terminal domain of WbdD contains an extended coiled-coil that physically separates WbdA from the catalytic domain of WbdD. The effects of insertions and deletions in the coiled-coil region were analyzed in vivo, revealing that polymer size is controlled by varying the length of the coiled-coil domain. Thus, the coiled-coil domain of WbdD functions as a molecular ruler that, along with WbdA:WbdD stoichiometry, controls the chain length of a model bacterial polysaccharide.
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Affiliation(s)
- Gregor Hagelueken
- Biomedical Sciences Research Complex, University of St Andrews, St Andrews, Fife, KY16 9ST, UK
- Institute for Physical and Theoretical Chemistry, University of Bonn, Wegelerstr. 12, 53115 Bonn, Germany
| | - Bradley R. Clarke
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, N1G 2W1, Canada
| | - Hexian Huang
- Biomedical Sciences Research Complex, University of St Andrews, St Andrews, Fife, KY16 9ST, UK
| | - Anne Tuukkanen
- European Molecular Biology Laboratory, Hamburg Outstation, Notkestraße 85, 22603 Hamburg, Germany
| | - Iulia Danciu
- European Molecular Biology Laboratory, Hamburg Outstation, Notkestraße 85, 22603 Hamburg, Germany
| | - Dmitri I. Svergun
- European Molecular Biology Laboratory, Hamburg Outstation, Notkestraße 85, 22603 Hamburg, Germany
| | | | - Huanting Liu
- Biomedical Sciences Research Complex, University of St Andrews, St Andrews, Fife, KY16 9ST, UK
| | - Chris Whitfield
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, N1G 2W1, Canada
| | - James H. Naismith
- Biomedical Sciences Research Complex, University of St Andrews, St Andrews, Fife, KY16 9ST, UK
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11
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Das R, Mahanti M, Mukhopadhyay B. Concise synthesis of the tetrasaccharide repeating unit of the O-polysaccharide isolated from Edwardsiella tarda PCM 1156 strain. Carbohydr Res 2014; 399:15-20. [DOI: 10.1016/j.carres.2014.08.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Revised: 07/24/2014] [Accepted: 08/04/2014] [Indexed: 10/24/2022]
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12
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Structural characterization and bioactivity of released exopolysaccharides from Lactobacillus plantarum 70810. Int J Biol Macromol 2014; 67:71-8. [DOI: 10.1016/j.ijbiomac.2014.02.056] [Citation(s) in RCA: 95] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Revised: 02/19/2014] [Accepted: 02/24/2014] [Indexed: 11/18/2022]
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13
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Lipopolysaccharide O antigen size distribution is determined by a chain extension complex of variable stoichiometry in Escherichia coli O9a. Proc Natl Acad Sci U S A 2014; 111:6407-12. [PMID: 24733938 DOI: 10.1073/pnas.1400814111] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The lengths of bacterial polysaccharides can be critical for their biological function. Unlike DNA or protein synthesis, where polymer length is implicit in the nucleic acid template, the molecular mechanisms for regulating polysaccharide length are poorly understood. Two models are commonly cited: a "molecular clock" regulates length by controlling the duration of the polymer extension process, whereas a "molecular ruler" determines length by measurement against a physical structure in the biosynthetic complex. Escherichia coli O9a is a prototype for the biosynthesis of O polysaccharides by ATP-binding cassette transporter-dependent processes. The length of the O9a polysaccharide is determined by two proteins: an extension enzyme, WbdA, and a termination enzyme, WbdD. WbdD is known to self-oligomerize and also to interact with WbdA. Changing either enzyme's concentration can alter the polysaccharide length. We quantified the O9a polysaccharide length distribution and the enzyme concentration dependence in vivo, then made mathematical models to predict the polymer length distributions resulting from hypothetical length-regulation mechanisms. Our data show qualitative features that cannot be explained by either a molecular clock or a molecular ruler model. Therefore, we propose a "variable geometry" model, in which a postulated biosynthetic WbdA-WbdD complex assembles with variable stoichiometry dependent on relative enzyme concentration. Each stoichiometry produces polymers with a distinct, geometrically determined, modal length. This model reproduces the enzyme concentration dependence and modality of the observed polysaccharide length distributions. Our work highlights limitations of previous models and provides new insight into the mechanisms of length control in polysaccharide biosynthesis.
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14
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Tian CC, Zha XQ, Pan LH, Luo JP. Structural characterization and antioxidant activity of a low-molecular polysaccharide from Dendrobium huoshanense. Fitoterapia 2013; 91:247-255. [PMID: 24096144 DOI: 10.1016/j.fitote.2013.09.018] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2013] [Revised: 09/24/2013] [Accepted: 09/25/2013] [Indexed: 12/15/2022]
Abstract
The present study aimed at investigating the structural features and antioxidant activities of a polysaccharide fraction (DHP1A) obtained from Dendrobium huoshanense, a precious herb medicine in China. DHP1A mainly consisted of mannose (Man), glucose (Glc) and a trace of galactose (Gal), with a molecular weight of 6700Da. Its backbone contained (1→4)-linked α-D-Glcp, (1→6)-linked α-D-Glcp and (1→4)-linked β-D-Manp, with a branch of terminal β-D-Galp. The in vitro antioxidant evaluation revealed that DHP1A had a remarkable inhibition effect on the FeCl2-induced lipid peroxidation. Furthermore, DHP1A pretreatment decreased the production of malondialdehyde (MDA), and restored the activities of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx), as well as the level of glutathione (GSH) in the livers of CCl4-treated mice. These results suggested that DHP1A was a potential antioxidant component in D. huoshanense.
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Affiliation(s)
- Chang-Cheng Tian
- School of Biotechnology and Food Engineering, Hefei University of Technology, Hefei 230009, PR China
| | - Xue-Qiang Zha
- School of Biotechnology and Food Engineering, Hefei University of Technology, Hefei 230009, PR China
| | - Li-Hua Pan
- School of Biotechnology and Food Engineering, Hefei University of Technology, Hefei 230009, PR China
| | - Jian-Ping Luo
- School of Biotechnology and Food Engineering, Hefei University of Technology, Hefei 230009, PR China.
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15
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Katzenellenbogen E, Kocharova NA, Shashkov AS, Górska-Frączek S, Gamian A, Knirel YA. Structure of the O-polysaccharide of Edwardsiella tarda PCM 1156. Carbohydr Res 2013; 374:45-8. [PMID: 23623959 DOI: 10.1016/j.carres.2013.03.025] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Revised: 03/22/2013] [Accepted: 03/24/2013] [Indexed: 10/27/2022]
Abstract
Mild acid degradation of the lipopolysaccharide of Edwardsiella tarda PCM 1156 afforded an O-polysaccharide, which was isolated by gel-permeation chromatography on Sephadex G-50 and studied by sugar and methylation analyses along with (1)H NMR and (13)C NMR spectroscopy, including 2D (1)H,(1)H COSY, TOCSY, ROESY, (1)H,(13)C HSQC, and HMBC experiments. The following structure of the linear tetrasaccharide repeating unit of the O-polysaccharide was established: [structure: see text].
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Affiliation(s)
- Ewa Katzenellenbogen
- L. Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Wrocław, Poland.
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16
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Staudacher E. Methylation--an uncommon modification of glycans. Biol Chem 2013; 393:675-85. [PMID: 22944672 DOI: 10.1515/hsz-2012-0132] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Accepted: 03/27/2012] [Indexed: 11/15/2022]
Abstract
A methyl (Me) group on a sugar residue is a rarely reported event. Until now, this type of modification has been found in the animal kingdom only in worms and molluscs, whereas it is more frequently present in some species of bacteria, fungi, algae and plants, but not in mammals. The monosaccharides involved as well as the positions of the Me groups on the sugar vary with species. Methylation appears to play a role in some recognition events, but details are still unknown. This review summarises the current knowledge on methylation of sugars in all types of organism.
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Affiliation(s)
- Erika Staudacher
- Department of Chemistry, University of Natural Resources and Life Sciences, Muthgasse 18, A-1190 Vienna, Austria.
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17
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Katzenellenbogen E, Kocharova NA, Shashkov AS, Górska-Frączek S, Bogulska M, Gamian A, Knirel YA. Structure of the O-polysaccharide of Edwardsiella tarda PCM 1150 containing an amide of D-glucuronic acid with L-alanine. Carbohydr Res 2012; 368:84-8. [PMID: 23348241 DOI: 10.1016/j.carres.2012.12.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2012] [Revised: 12/12/2012] [Accepted: 12/14/2012] [Indexed: 10/27/2022]
Abstract
Mild acid degradation of the lipopolysaccharide of Edwardsiella tarda PCM 1150 afforded an O-polysaccharide, which was isolated by GPC on Sephadex G-50 and studied by sugar and methylation analyses along with 1D and 2D 1H and 13C NMR spectroscopies, including experiments performed in a 9:1 H2O/D2O mixture to detect NH protons and their correlations with CH protons. The O-polysaccharide was found to contain an amide of d-glucuronic acid with l-alanine (d-GlcA6Ala) and the following structure of the branched hexasaccharide repeating unit was established: -->4)-β-D-GlepA6Ala-(1-->4)-α-L-Fucp-(1-->4)-α-D-Glcp-(1-->4)-α-D-Quip-(1-->3)-β-D-GlcpNAc-(1-->3<--1α-D-GalpNAc.
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Affiliation(s)
- Ewa Katzenellenbogen
- L. Hirszfeld Institute of Immunology and Experimental Therapy, Polish Academy of Sciences, Weigla 12, 53-114 Wrocław, Poland.
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18
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Greenfield LK, Richards MR, Vinogradov E, Wakarchuk WW, Lowary TL, Whitfield C. Domain organization of the polymerizing mannosyltransferases involved in synthesis of the Escherichia coli O8 and O9a lipopolysaccharide O-antigens. J Biol Chem 2012; 287:38135-49. [PMID: 22989876 PMCID: PMC3488083 DOI: 10.1074/jbc.m112.412577] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2012] [Revised: 09/16/2012] [Indexed: 11/06/2022] Open
Abstract
The Escherichia coli O9a and O8 polymannose O-polysaccharides (O-PSs) serve as model systems for the biosynthesis of bacterial polysaccharides by ATP-binding cassette transporter-dependent pathways. Both O-PSs contain a conserved primer-adaptor domain at the reducing terminus and a serotype-specific repeat unit domain. The repeat unit domain is polymerized by the serotype-specific WbdA mannosyltransferase. In serotype O9a, WbdA is a bifunctional α-(1→2)-, α-(1→3)-mannosyltransferase, and its counterpart in serotype O8 is trifunctional (α-(1→2), α-(1→3), and β-(1→2)). Little is known about the detailed structures or mechanisms of action of the WbdA polymerases, and here we establish that they are multidomain enzymes. WbdA(O9a) contains two separable and functionally active domains, whereas WbdA(O8) possesses three. In WbdC(O9a) and WbdB(O9a), substitution of the first Glu of the EX(7)E motif had detrimental effects on the enzyme activity, whereas substitution of the second had no significant effect on activity in vivo. Mutation of the Glu residues in the EX(7)E motif of the N-terminal WbdA(O9a) domain resulted in WbdA variants unable to synthesize O-PS. In contrast, mutation of the Glu residues in the motif of the C-terminal WbdA(O9a) domain generated an enzyme capable of synthesizing an altered O-PS repeat unit consisting of only α-(1→2) linkages. In vitro assays with synthetic acceptors unequivocally confirmed that the N-terminal domain of WbdA(O9a) possesses α-(1→2)-mannosyltransferase activity. Together, these studies form a framework for detailed structure-function studies on individual domains and a strategy applicable for dissection and analysis of other multidomain glycosyltransferases.
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Affiliation(s)
- Laura K. Greenfield
- From the Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1
| | - Michele R. Richards
- the Alberta Glycomics Centre and Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, and
| | - Evgeny Vinogradov
- the Institute for Biological Sciences, National Research Council of Canada, Ottawa, Ontario K1A 0R6, Canada
| | - Warren W. Wakarchuk
- the Institute for Biological Sciences, National Research Council of Canada, Ottawa, Ontario K1A 0R6, Canada
| | - Todd L. Lowary
- the Alberta Glycomics Centre and Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, and
| | - Chris Whitfield
- From the Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1
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19
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Hagelueken G, Huang H, Clarke BR, Lebl T, Whitfield C, Naismith JH. Structure of WbdD: a bifunctional kinase and methyltransferase that regulates the chain length of the O antigen in Escherichia coli O9a. Mol Microbiol 2012; 86:730-42. [PMID: 22970759 PMCID: PMC3482155 DOI: 10.1111/mmi.12014] [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] [Accepted: 08/24/2012] [Indexed: 02/05/2023]
Abstract
The Escherichia coli serotype O9a O-antigen polysaccharide (O-PS) is a model for glycan biosynthesis and export by the ATP-binding cassette transporter-dependent pathway. The polymannose O9a O-PS is synthesized as a polyprenol-linked glycan by mannosyltransferase enzymes located at the cytoplasmic membrane. The chain length of the O9a O-PS is tightly regulated by the WbdD enzyme. WbdD first phosphorylates the terminal non-reducing mannose of the O-PS and then methylates the phosphate, stopping polymerization. The 2.2 Å resolution structure of WbdD reveals a bacterial methyltransferase domain joined to a eukaryotic kinase domain. The kinase domain is again fused to an extended C-terminal coiled-coil domain reminiscent of eukaryotic DMPK (Myotonic Dystrophy Protein Kinase) family kinases such as Rho-associated protein kinase (ROCK). WbdD phosphorylates 2-α-d-mannosyl-d-mannose (2α-MB), a short mimic of the O9a polymer. Mutagenesis identifies those residues important in catalysis and substrate recognition and the in vivo phenotypes of these mutants are used to dissect the termination reaction. We have determined the structures of co-complexes of WbdD with two known eukaryotic protein kinase inhibitors. Although these are potent inhibitors in vitro, they do not show any in vivo activity. The structures reveal new insight into O-PS chain-length regulation in this important model system.
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Affiliation(s)
- Gregor Hagelueken
- Biomedical Sciences Research Complex, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9ST, UK
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20
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Greenfield LK, Richards MR, Li J, Wakarchuk WW, Lowary TL, Whitfield C. Biosynthesis of the polymannose lipopolysaccharide O-antigens from Escherichia coli serotypes O8 and O9a requires a unique combination of single- and multiple-active site mannosyltransferases. J Biol Chem 2012; 287:35078-35091. [PMID: 22875852 DOI: 10.1074/jbc.m112.401000] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Escherichia coli O9a and O8 O-antigen serotypes represent model systems for the ABC transporter-dependent synthesis of bacterial polysaccharides. The O9a and O8 antigens are linear mannose homopolymers containing conserved reducing termini (the primer-adaptor), a serotype-specific repeat unit domain, and a terminator. Synthesis of these glycans occurs on the polyisoprenoid lipid-linked primer, undecaprenol pyrophosphoryl-GlcpNAc, by two conserved mannosyltransferases, WbdC and WbdB, and a serotype-specific mannosyltransferase, WbdA. The glycan structure and pattern of conservation in the O9a and O8 mannosyltransferases are not consistent with the existing model of O9a biosynthesis. Here we establish a revised pathway using a combination of in vivo (mutant complementation) experiments and in vitro strategies with purified enzymes and synthetic acceptors. WbdC and WbdB synthesize the adaptor region, where they transfer one and two α-(1→3)-linked mannose residues, respectively. The WbdA enzymes are solely responsible for forming the repeat unit domains of these O-antigens. WbdA(O9a) has two predicted active sites and polymerizes a tetrasaccharide repeat unit containing two α-(1→3)- and two α-(1→2)-linked mannopyranose residues. In contrast, WbdA(O8) polymerizes trisaccharide repeat units containing single α-(1→3)-, α-(1→2)-, and β-(1→2)-mannopyranoses. These studies illustrate assembly systems exploiting several mannosyltransferases with flexible active sites, arranged in single- and multiple-domain formats.
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Affiliation(s)
- Laura K Greenfield
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario N1G 2W1, Canada
| | - Michele R Richards
- Alberta Glycomics Centre and Department of Chemistry, University of Alberta, Edmonton, Alberta T6G 2G2, Canada
| | - Jianjun Li
- Institute for Biological Sciences, National Research Council of Canada, Ottawa, Ontario K1A 0R6, Canada
| | - Warren W Wakarchuk
- Institute for Biological Sciences, National Research Council of Canada, Ottawa, Ontario K1A 0R6, Canada
| | - 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, Guelph, Ontario N1G 2W1, Canada.
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