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Zhong C, Nidetzky B. Bottom-Up Synthesized Glucan Materials: Opportunities from Applied Biocatalysis. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2024; 36:e2400436. [PMID: 38514194 DOI: 10.1002/adma.202400436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2024] [Revised: 03/05/2024] [Indexed: 03/23/2024]
Abstract
Linear d-glucans are natural polysaccharides of simple chemical structure. They are comprised of d-glucosyl units linked by a single type of glycosidic bond. Noncovalent interactions within, and between, the d-glucan chains give rise to a broad variety of macromolecular nanostructures that can assemble into crystalline-organized materials of tunable morphology. Structure design and functionalization of d-glucans for diverse material applications largely relies on top-down processing and chemical derivatization of naturally derived starting materials. The top-down approach encounters critical limitations in efficiency, selectivity, and flexibility. Bottom-up approaches of d-glucan synthesis offer different, and often more precise, ways of polymer structure control and provide means of functional diversification widely inaccessible to top-down routes of polysaccharide material processing. Here the natural and engineered enzymes (glycosyltransferases, glycoside hydrolases and phosphorylases, glycosynthases) for d-glucan polymerization are described and the use of applied biocatalysis for the bottom-up assembly of specific d-glucan structures is shown. Advanced material applications of the resulting polymeric products are further shown and their important role in the development of sustainable macromolecular materials in a bio-based circular economy is discussed.
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Affiliation(s)
- Chao Zhong
- Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, NAWI Graz, Petersgasse 12, Graz, 8010, Austria
| | - Bernd Nidetzky
- Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, NAWI Graz, Petersgasse 12, Graz, 8010, Austria
- Austrian Centre of Industrial Biotechnology (acib), Krenngasse 37, Graz, 8010, Austria
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Stratilová B, Šesták S, Stratilová E, Vadinová K, Kozmon S, Hrmova M. Engineering of substrate specificity in a plant cell-wall modifying enzyme through alterations of carboxyl-terminal amino acid residues. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2023; 116:1529-1544. [PMID: 37658783 DOI: 10.1111/tpj.16435] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Revised: 08/07/2023] [Accepted: 08/12/2023] [Indexed: 09/05/2023]
Abstract
Structural determinants of substrate recognition remain inadequately defined in broad specific cell-wall modifying enzymes, termed xyloglucan xyloglucosyl transferases (XETs). Here, we investigate the Tropaeolum majus seed TmXET6.3 isoform, a member of the GH16_20 subfamily of the GH16 network. This enzyme recognises xyloglucan (XG)-derived donors and acceptors, and a wide spectrum of other chiefly saccharide substrates, although it lacks the activity with homogalacturonan (pectin) fragments. We focus on defining the functionality of carboxyl-terminal residues in TmXET6.3, which extend acceptor binding regions in the GH16_20 subfamily but are absent in the related GH16_21 subfamily. Site-directed mutagenesis using double to quintuple mutants in the carboxyl-terminal region - substitutions emulated on barley XETs recognising the XG/penta-galacturonide acceptor substrate pair - demonstrated that this activity could be gained in TmXET6.3. We demonstrate the roles of semi-conserved Arg238 and Lys237 residues, introducing a net positive charge in the carboxyl-terminal region (which complements a negative charge of the acidic penta-galacturonide) for the transfer of xyloglucan fragments. Experimental data, supported by molecular modelling of TmXET6.3 with the XG oligosaccharide donor and penta-galacturonide acceptor substrates, indicated that they could be accommodated in the active site. Our findings support the conclusion on the significance of positively charged residues at the carboxyl terminus of TmXET6.3 and suggest that a broad specificity could be engineered via modifications of an acceptor binding site. The definition of substrate specificity in XETs should prove invaluable for defining the structure, dynamics, and function of plant cell walls, and their metabolism; these data could be applicable in various biotechnologies.
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Affiliation(s)
- Barbora Stratilová
- Institute of Chemistry, Slovak Academy of Sciences, SK-84538, Bratislava, Slovakia
| | - Sergej Šesták
- Institute of Chemistry, Slovak Academy of Sciences, SK-84538, Bratislava, Slovakia
| | - Eva Stratilová
- Institute of Chemistry, Slovak Academy of Sciences, SK-84538, Bratislava, Slovakia
| | - Kristína Vadinová
- Institute of Chemistry, Slovak Academy of Sciences, SK-84538, Bratislava, Slovakia
| | - Stanislav Kozmon
- Institute of Chemistry, Slovak Academy of Sciences, SK-84538, Bratislava, Slovakia
| | - Maria Hrmova
- School of Agriculture, Food and Wine & Waite Research Institute, University of Adelaide, Waite Research Precinct, Glen Osmond, South Australia, 5064, Australia
- Jiangsu Collaborative Innovation Centre for Regional Modern Agriculture and Environmental Protection, School of Life Science, Huaiyin Normal University, Huai'an, 223300, China
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Sun Y, Wu Y, Ma D, Li JJ, Liu X, You Y, Lu J, Liu Z, Cheng X, Du Y. Digital microfluidics-engaged automated enzymatic degradation and synthesis of oligosaccharides. Front Bioeng Biotechnol 2023; 11:1201300. [PMID: 37415787 PMCID: PMC10320006 DOI: 10.3389/fbioe.2023.1201300] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2023] [Accepted: 06/08/2023] [Indexed: 07/08/2023] Open
Abstract
Glycans are an important group of natural biopolymers, which not only play the role of a major biological energy resource but also as signaling molecules. As a result, structural characterization or sequencing of glycans, as well as targeted synthesis of glycans, is of great interest for understanding their structure-function relationship. However, this generally involves tedious manual operations and high reagent consumptions, which are the main technical bottlenecks retarding the advances of both automatic glycan sequencing and synthesis. Until now, automated enzymatic glycan sequencers or synthesizers are still not available on the market. In this study, to promote the development of automation in glycan sequencing or synthesis, first, programmed degradation and synthesis of glycans catalyzed by enzymes were successfully conducted on a digital microfluidic (DMF) device by using microdroplets as microreactors. In order to develop automatic glycan synthesizers and sequencers, a strategy integrating enzymatic oligosaccharide degradation or synthesis and magnetic manipulation to realize the separation and purification process after enzymatic reactions was designed and performed on DMF. An automatic process for enzymatic degradation of tetra-N-acetyl chitotetraose was achieved. Furthermore, the two-step enzymatic synthesis of lacto-N-tetraose was successfully and efficiently completed on the DMF platform. This work demonstrated here would open the door to further develop automatic enzymatic glycan synthesizers or sequencers based on DMF.
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Affiliation(s)
- Yunze Sun
- School of Chemical Engineering, University of Chinese Academy of Sciences, Beijing, China
- State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, China
| | - Yiran Wu
- School of Chemical Engineering, University of Chinese Academy of Sciences, Beijing, China
- State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, China
| | - Dachuan Ma
- Department of Biotechnology, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning, China
| | - Jian-Jun Li
- State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, China
| | - Xianming Liu
- Department of Biotechnology, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning, China
| | - Yuanjiang You
- State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, China
| | - Jun Lu
- Institute of Physics, Chinese Academy of Sciences, Beijing, China
| | - Zhen Liu
- Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen, China
| | - Xin Cheng
- Department of Materials Science and Engineering, Southern University of Science and Technology, Shenzhen, China
| | - Yuguang Du
- State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, China
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4
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Hrmova M, Stratilová B, Stratilová E. Broad Specific Xyloglucan:Xyloglucosyl Transferases Are Formidable Players in the Re-Modelling of Plant Cell Wall Structures. Int J Mol Sci 2022; 23:ijms23031656. [PMID: 35163576 PMCID: PMC8836008 DOI: 10.3390/ijms23031656] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 01/25/2022] [Accepted: 01/26/2022] [Indexed: 01/27/2023] Open
Abstract
Plant xyloglucan:xyloglucosyl transferases, known as xyloglucan endo-transglycosylases (XETs) are the key players that underlie plant cell wall dynamics and mechanics. These fundamental roles are central for the assembly and modifications of cell walls during embryogenesis, vegetative and reproductive growth, and adaptations to living environments under biotic and abiotic (environmental) stresses. XET enzymes (EC 2.4.1.207) have the β-sandwich architecture and the β-jelly-roll topology, and are classified in the glycoside hydrolase family 16 based on their evolutionary history. XET enzymes catalyse transglycosylation reactions with xyloglucan (XG)-derived and other than XG-derived donors and acceptors, and this poly-specificity originates from the structural plasticity and evolutionary diversification that has evolved through expansion and duplication. In phyletic groups, XETs form the gene families that are differentially expressed in organs and tissues in time- and space-dependent manners, and in response to environmental conditions. Here, we examine higher plant XET enzymes and dissect how their exclusively carbohydrate-linked transglycosylation catalytic function inter-connects complex plant cell wall components. Further, we discuss progress in technologies that advance the knowledge of plant cell walls and how this knowledge defines the roles of XETs. We construe that the broad specificity of the plant XETs underscores their roles in continuous cell wall restructuring and re-modelling.
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Affiliation(s)
- Maria Hrmova
- Jiangsu Collaborative Innovation Centre for Regional Modern Agriculture and Environmental Protection, School of Life Science, Huaiyin Normal University, Huai’an 223300, China
- School of Agriculture, Food and Wine & Waite Research Institute, University of Adelaide, Glen Osmond, SA 5064, Australia
- Correspondence: ; Tel.: +61-8-8313-0775
| | - Barbora Stratilová
- Institute of Chemistry, Centre for Glycomics, Slovak Academy of Sciences, SK-84538 Bratislava, Slovakia; (B.S.); (E.S.)
- Faculty of Natural Sciences, Department of Physical and Theoretical Chemistry, Comenius University, SK-84215 Bratislava, Slovakia
| | - Eva Stratilová
- Institute of Chemistry, Centre for Glycomics, Slovak Academy of Sciences, SK-84538 Bratislava, Slovakia; (B.S.); (E.S.)
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Ruprecht C, Pfrengle F. Synthetic Plant Glycan Microarrays as Tools for Plant Biology. Methods Mol Biol 2022; 2460:115-125. [PMID: 34972933 DOI: 10.1007/978-1-0716-2148-6_7] [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] [Indexed: 06/14/2023]
Abstract
Chemically synthesized plant oligosaccharides have recently evolved as powerful molecular tools for plant cell wall biology. Synthetic plant glycan microarrays equipped with these oligosaccharides enable high-throughput analyses of glycan-binding proteins and carbohydrate-active enzymes. To produce these glycan microarrays, small amounts of glycan solution are printed on suitable surfaces for covalent or non-covalent immobilization. Synthetic plant glycan microarrays have been used for example to map the epitopes of plant cell wall-directed antibodies, to characterize glycosyl hydrolases and glycosyl transferases, and to analyze lectin binding. In this chapter, detailed experimental procedures for the production of synthetic glycan microarrays and their use for the characterization of cell wall glycan-directed antibodies are described.
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Affiliation(s)
- Colin Ruprecht
- Department of Biomolecular Systems, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany
- Department of Chemistry, University of Natural Resources and Life Sciences Vienna, Vienna, Austria
| | - Fabian Pfrengle
- Department of Biomolecular Systems, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany.
- Department of Chemistry, University of Natural Resources and Life Sciences Vienna, Vienna, Austria.
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6
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Stratilová B, Kozmon S, Stratilová E, Hrmova M. Plant Xyloglucan Xyloglucosyl Transferases and the Cell Wall Structure: Subtle but Significant. Molecules 2020; 25:E5619. [PMID: 33260399 PMCID: PMC7729885 DOI: 10.3390/molecules25235619] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2020] [Revised: 11/25/2020] [Accepted: 11/26/2020] [Indexed: 12/16/2022] Open
Abstract
Plant xyloglucan xyloglucosyl transferases or xyloglucan endo-transglycosylases (XET; EC 2.4.1.207) catalogued in the glycoside hydrolase family 16 constitute cell wall-modifying enzymes that play a fundamental role in the cell wall expansion and re-modelling. Over the past thirty years, it has been established that XET enzymes catalyse homo-transglycosylation reactions with xyloglucan (XG)-derived substrates and hetero-transglycosylation reactions with neutral and charged donor and acceptor substrates other than XG-derived. This broad specificity in XET isoforms is credited to a high degree of structural and catalytic plasticity that has evolved ubiquitously in algal, moss, fern, basic Angiosperm, monocot, and eudicot enzymes. These XET isoforms constitute gene families that are differentially expressed in tissues in time- and space-dependent manners during plant growth and development, and in response to biotic and abiotic stresses. Here, we discuss the current state of knowledge of broad specific plant XET enzymes and how their inherently carbohydrate-based transglycosylation reactions tightly link with structural diversity that underlies the complexity of plant cell walls and their mechanics. Based on this knowledge, we conclude that multi- or poly-specific XET enzymes are widespread in plants to allow for modifications of the cell wall structure in muro, a feature that implements the multifaceted roles in plant cells.
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Affiliation(s)
- Barbora Stratilová
- Institute of Chemistry, Centre for Glycomics, Slovak Academy of Sciences, Dúbravská cesta 9, SK-84538 Bratislava, Slovakia; (B.S.); (S.K.); (E.S.)
- Faculty of Natural Sciences, Department of Physical and Theoretical Chemistry, Comenius University, Mlynská Dolina, SK-84215 Bratislava, Slovakia
| | - Stanislav Kozmon
- Institute of Chemistry, Centre for Glycomics, Slovak Academy of Sciences, Dúbravská cesta 9, SK-84538 Bratislava, Slovakia; (B.S.); (S.K.); (E.S.)
| | - Eva Stratilová
- Institute of Chemistry, Centre for Glycomics, Slovak Academy of Sciences, Dúbravská cesta 9, SK-84538 Bratislava, Slovakia; (B.S.); (S.K.); (E.S.)
| | - Maria Hrmova
- School of Life Science, Huaiyin Normal University, Huai’an 223300, China
- School of Agriculture, Food and Wine, University of Adelaide, Glen Osmond, SA 5064, Australia
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7
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Stratilová B, Šesták S, Mravec J, Garajová S, Pakanová Z, Vadinová K, Kučerová D, Kozmon S, Schwerdt JG, Shirley N, Stratilová E, Hrmova M. Another building block in the plant cell wall: Barley xyloglucan xyloglucosyl transferases link covalently xyloglucan and anionic oligosaccharides derived from pectin. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2020; 104:752-767. [PMID: 32799357 DOI: 10.1111/tpj.14964] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Revised: 07/17/2020] [Accepted: 07/29/2020] [Indexed: 05/27/2023]
Abstract
We report on the homo- and hetero-transglycosylation activities of the HvXET3 and HvXET4 xyloglucan xyloglucosyl transferases (XET; EC 2.4.1.207) from barley (Hordeum vulgare L.), and the visualisation of these activities in young barley roots using Alexa Fluor 488-labelled oligosaccharides. We discover that these isozymes catalyse the transglycosylation reactions with the chemically defined donor and acceptor substrates, specifically with the xyloglucan donor and the penta-galacturonide [α(1-4)GalAp]5 acceptor - the homogalacturonan (pectin) fragment. This activity is supported by 3D molecular models of HvXET3 and HvXET4 with the docked XXXG donor and [α(1-4)GalAp]5 acceptor substrates at the -4 to +5 subsites in the active sites. Comparative sequence analyses of barley isoforms and seed-localised TmXET6.3 from nasturtium (Tropaeolum majus L.) permitted the engineering of mutants of TmXET6.3 that could catalyse the hetero-transglycosylation reaction with the xyloglucan/[α(1-4)GalAp]5 substrate pair, while wild-type TmXET6.3 lacked this activity. Expression data obtained by real-time quantitative polymerase chain reaction of HvXET transcripts and a clustered heatmap of expression profiles of the gene family revealed that HvXET3 and HvXET6 co-expressed but did not share the monophyletic origin. Conversely, HvXET3 and HvXET4 shared this relationship, when we examined the evolutionary history of 419 glycoside hydrolase 16 family members, spanning monocots, eudicots and a basal Angiosperm. The discovered hetero-transglycosylation activity in HvXET3 and HvXET4 with the xyloglucan/[α(1-4)GalAp]5 substrate pair is discussed against the background of roles of xyloglucan-pectin heteropolymers and how they may participate in spatial patterns of cell wall formation and re-modelling, and affect the structural features of walls.
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Affiliation(s)
- Barbora Stratilová
- Institute of Chemistry, Centre for Glycomics, Slovak Academy of Sciences, Dúbravská cesta 9, Bratislava, SK-84538, Slovakia
- Faculty of Natural Sciences, Department of Physical and Theoretical Chemistry, Comenius University, Mlynská dolina, Bratislava, SK-842 15, Slovakia
| | - Sergej Šesták
- Institute of Chemistry, Centre for Glycomics, Slovak Academy of Sciences, Dúbravská cesta 9, Bratislava, SK-84538, Slovakia
| | - Jozef Mravec
- Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, Frederiksberg-C, 1871, Denmark
| | - Soňa Garajová
- Institute of Chemistry, Centre for Glycomics, Slovak Academy of Sciences, Dúbravská cesta 9, Bratislava, SK-84538, Slovakia
- School of Agriculture, Food and Wine, University of Adelaide, Glen Osmond, SA, 5064, Australia
| | - Zuzana Pakanová
- Institute of Chemistry, Centre for Glycomics, Slovak Academy of Sciences, Dúbravská cesta 9, Bratislava, SK-84538, Slovakia
| | - Kristína Vadinová
- Institute of Chemistry, Centre for Glycomics, Slovak Academy of Sciences, Dúbravská cesta 9, Bratislava, SK-84538, Slovakia
| | - Danica Kučerová
- Institute of Chemistry, Centre for Glycomics, Slovak Academy of Sciences, Dúbravská cesta 9, Bratislava, SK-84538, Slovakia
| | - Stanislav Kozmon
- Institute of Chemistry, Centre for Glycomics, Slovak Academy of Sciences, Dúbravská cesta 9, Bratislava, SK-84538, Slovakia
| | - Julian G Schwerdt
- School of Agriculture, Food and Wine, University of Adelaide, Glen Osmond, SA, 5064, Australia
| | - Neil Shirley
- School of Agriculture, Food and Wine, University of Adelaide, Glen Osmond, SA, 5064, Australia
| | - Eva Stratilová
- Institute of Chemistry, Centre for Glycomics, Slovak Academy of Sciences, Dúbravská cesta 9, Bratislava, SK-84538, Slovakia
| | - Maria Hrmova
- School of Agriculture, Food and Wine, University of Adelaide, Glen Osmond, SA, 5064, Australia
- School of Life Sciences, Huaiyin Normal University, Huai'an, 223300, China
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Holland C, Simmons TJ, Meulewaeter F, Hudson A, Fry SC. Three highly acidic Equisetum XTHs differ from hetero-trans-β-glucanase in donor substrate specificity and are predominantly xyloglucan homo-transglucosylases. JOURNAL OF PLANT PHYSIOLOGY 2020; 251:153210. [PMID: 32544741 DOI: 10.1016/j.jplph.2020.153210] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Revised: 05/20/2020] [Accepted: 05/24/2020] [Indexed: 05/27/2023]
Abstract
Transglycanases are enzymes that remodel the primary cell wall in plants, potentially loosening and/or strengthening it. Xyloglucan endotransglucosylase (XET; EC 2.4.1.207), ubiquitous in land plants, is a homo-transglucanase activity (donor, xyloglucan; acceptor, xyloglucan) exhibited by XTH (xyloglucan endotransglucosylase/hydrolase) proteins. By contrast, hetero-trans-β-glucanase (HTG) is the only known enzyme that is preferentially a hetero-transglucanase. Its two main hetero-transglucanase activities are MLG : xyloglucan endotransglucosylase (MXE) and cellulose : xyloglucan endotransglucosylase (CXE). HTG is highly acidic and found only in the evolutionarily isolated genus of fern-allies, Equisetum. We now report genes for three new highly acidic HTG-related XTHs in E. fluviatile (EfXTH-A, EfXTH-H and EfXTH-I). We expressed them heterologously in Pichia and tested the encoded proteins' enzymic activities to determine whether their acidity and/or their Equisetum-specific sequences might confer high hetero-transglucanase activity. Untransformed Pichia was found to secrete MLG-degrading enzyme(s), which had to be removed for reliable MXE assays. All three acidic EfXTHs exhibited very predominantly XET activity, although low but measurable hetero-transglucanase activities (MXE and CXE) were also detected in EfXTH-H and EfXTH-I. We conclude that the extremely high hetero-transglucanase activities of Equisetum HTG are not emulated by similarly acidic Equisetum XTHs that share up to 55.5% sequence identity with HTG.
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Affiliation(s)
- Claire Holland
- The Edinburgh Cell Wall Group, Institute of Molecular Plant Sciences, The University of Edinburgh, Daniel Rutherford Building, The King's Buildings, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Thomas J Simmons
- The Edinburgh Cell Wall Group, Institute of Molecular Plant Sciences, The University of Edinburgh, Daniel Rutherford Building, The King's Buildings, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Frank Meulewaeter
- BASF Innovation Center Gent- Trait Research, Technologiepark-Zwijnaarde, 9052 Gent, Belgium
| | - Andrew Hudson
- Institute of Molecular Plant Sciences, The University of Edinburgh, Daniel Rutherford Building, The King's Buildings, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Stephen C Fry
- The Edinburgh Cell Wall Group, Institute of Molecular Plant Sciences, The University of Edinburgh, Daniel Rutherford Building, The King's Buildings, Max Born Crescent, Edinburgh EH9 3BF, UK.
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9
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Abstract
Transglycanases (endotransglycosylases) are enzymes that "cut and paste" polysaccharide chains. Several transglycanase activities have been discovered which can cut (i.e., use as donor substrate) each of the major hemicelluloses [xyloglucan, mannans, xylans, and mixed-linkage β-glucan (MLG)], and, as a recent addition, cellulose. These enzymes may play interesting roles in adjusting the wall's physical properties, influencing cell expansion, stem strengthening, and fruit softening.Activities discussed include the homotransglycanases XET (xyloglucan endotransglucosylase, i.e., xyloglucan-xyloglucan endotransglycosylase), trans-β-mannanase (mannan -mannan endotransglycosylase), and trans-β-xylanase (xylan -xylan endotransglucosylase), plus the heterotransglycanases MXE (MLG -xyloglucan endotransglucosylase) and CXE (cellulose -xyloglucan endotransglucosylase).Transglycanases acting on polysaccharide donor substrates can utilize small, labeled oligosaccharides as acceptor substrates, generating easily recognizable polymeric labeled products. We present methods for extracting transglycanases from plant tissues and assaying them in vitro, either quantitatively in solution assays or by high-throughput dot-blot screens. Both radioactively and fluorescently labeled substrates are mentioned. A general procedure (glass-fiber blotting) is illustrated by which proposed novel transglycanase activities can be tested for.In addition, we describe strategies for detecting transglycanase action in vivo. These methods enable the quantification of, separately, XET and MXE action in Equisetum stems. Related methods enable the tissue distribution of transglycanase action to be visualized cytologically.
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Affiliation(s)
- Lenka Franková
- The Edinburgh Cell Wall Group, Institute of Molecular Plant Sciences, The University of Edinburgh, Edinburgh, UK
| | - Stephen C Fry
- The Edinburgh Cell Wall Group, Institute of Molecular Plant Sciences, The University of Edinburgh, Edinburgh, UK.
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10
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Stratilová B, Firáková Z, Klaudiny J, Šesták S, Kozmon S, Strouhalová D, Garajová S, Ait-Mohand F, Horváthová Á, Farkaš V, Stratilová E, Hrmova M. Engineering the acceptor substrate specificity in the xyloglucan endotransglycosylase TmXET6.3 from nasturtium seeds (Tropaeolum majus L.). PLANT MOLECULAR BIOLOGY 2019; 100:181-197. [PMID: 30868545 DOI: 10.1007/s11103-019-00852-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2018] [Accepted: 02/28/2019] [Indexed: 06/09/2023]
Abstract
The knowledge of substrate specificity of XET enzymes is important for the general understanding of metabolic pathways to challenge the established notion that these enzymes operate uniquely on cellulose-xyloglucan networks. Xyloglucan xyloglucosyl transferases (XETs) (EC 2.4.1.207) play a central role in loosening and re-arranging the cellulose-xyloglucan network, which is assumed to be the primary load-bearing structural component of plant cell walls. The sequence of mature TmXET6.3 from Tropaeolum majus (280 residues) was deduced by the nucleotide sequence analysis of complete cDNA by Rapid Amplification of cDNA Ends, based on tryptic and chymotryptic peptide sequences. Partly purified TmXET6.3, expressed in Pichia occurred in N-glycosylated and unglycosylated forms. The quantification of hetero-transglycosylation activities of TmXET6.3 revealed that (1,3;1,4)-, (1,6)- and (1,4)-β-D-glucooligosaccharides were the preferred acceptor substrates, while (1,4)-β-D-xylooligosaccharides, and arabinoxylo- and glucomanno-oligosaccharides were less preferred. The 3D model of TmXET6.3, and bioinformatics analyses of identified and putative plant xyloglucan endotransglycosylases (XETs)/hydrolases (XEHs) of the GH16 family revealed that H94, A104, Q108, K234 and K237 were the key residues that underpinned the acceptor substrate specificity of TmXET6.3. Compared to the wild-type enzyme, the single Q108R and K237T, and double-K234T/K237T and triple-H94Q/A104D/Q108R variants exhibited enhanced hetero-transglycosylation activities with xyloglucan and (1,4)-β-D-glucooligosaccharides, while those with (1,3;1,4)- and (1,6)-β-D-glucooligosaccharides were suppressed; the incorporation of xyloglucan to (1,4)-β-D-glucooligosaccharides by the H94Q variant was influenced most extensively. Structural and biochemical data of non-specific TmXET6.3 presented here extend the classic XET reaction mechanism by which these enzymes operate in plant cell walls. The evaluations of TmXET6.3 transglycosylation activities and the incidence of investigated residues in other members of the GH16 family suggest that a broad acceptor substrate specificity in plant XET enzymes could be more widespread than previously anticipated.
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Affiliation(s)
- Barbora Stratilová
- Centre for Glycomics, Institute of Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, 84538, Bratislava, Slovakia
- Department of Physical and Theoretical Chemistry, Faculty of Natural Sciences, Comenius University, Mlynská dolina, 842 15, Bratislava, Slovakia
| | - Zuzana Firáková
- Centre for Glycomics, Institute of Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, 84538, Bratislava, Slovakia
| | - Jaroslav Klaudiny
- Centre for Glycomics, Institute of Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, 84538, Bratislava, Slovakia
| | - Sergej Šesták
- Centre for Glycomics, Institute of Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, 84538, Bratislava, Slovakia
| | - Stanislav Kozmon
- Centre for Glycomics, Institute of Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, 84538, Bratislava, Slovakia
| | - Dana Strouhalová
- Institute of Analytical Chemistry, Czech Academy of Sciences, v.v.i. Veveří, 60200, Brno, Czech Republic
| | - Soňa Garajová
- Centre for Glycomics, Institute of Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, 84538, Bratislava, Slovakia
| | - Fairouz Ait-Mohand
- Centre for Glycomics, Institute of Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, 84538, Bratislava, Slovakia
| | - Ágnes Horváthová
- Centre for Glycomics, Institute of Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, 84538, Bratislava, Slovakia
| | - Vladimír Farkaš
- Centre for Glycomics, Institute of Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, 84538, Bratislava, Slovakia
| | - Eva Stratilová
- Centre for Glycomics, Institute of Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, 84538, Bratislava, Slovakia
| | - Maria Hrmova
- School of Life Sciences, Huaiyin Normal University, Huai'an, 223300, China.
- School of Agriculture, Food and Wine, and Waite Research Institute, Waite Research Precinct, University of Adelaide, Glen Osmond, SA, 5064, Australia.
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11
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Wen L, Edmunds G, Gibbons C, Zhang J, Gadi MR, Zhu H, Fang J, Liu X, Kong Y, Wang PG. Toward Automated Enzymatic Synthesis of Oligosaccharides. Chem Rev 2018; 118:8151-8187. [DOI: 10.1021/acs.chemrev.8b00066] [Citation(s) in RCA: 112] [Impact Index Per Article: 18.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Liuqing Wen
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30303, United States
| | - Garrett Edmunds
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30303, United States
| | - Christopher Gibbons
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30303, United States
| | - Jiabin Zhang
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30303, United States
| | - Madhusudhan Reddy Gadi
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30303, United States
| | - Hailiang Zhu
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30303, United States
| | - Junqiang Fang
- National Glycoengineering Research Center and State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100, China
| | - Xianwei Liu
- National Glycoengineering Research Center and State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100, China
| | - Yun Kong
- National Glycoengineering Research Center and State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100, China
| | - Peng George Wang
- Department of Chemistry, Georgia State University, Atlanta, Georgia 30303, United States
- National Glycoengineering Research Center and State Key Laboratory of Microbial Technology, Shandong University, Jinan 250100, China
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12
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Ruprecht C, Dallabernardina P, Smith PJ, Urbanowicz BR, Pfrengle F. Analyzing Xyloglucan Endotransglycosylases by Incorporating Synthetic Oligosaccharides into Plant Cell Walls. Chembiochem 2018; 19:793-798. [PMID: 29384258 DOI: 10.1002/cbic.201700638] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2017] [Indexed: 12/29/2022]
Abstract
The plant cell wall is a cellular exoskeleton consisting predominantly of a complex polysaccharide network that defines the shape of cells. During growth, this network can be loosened through the action of xyloglucan endotransglycosylases (XETs), glycoside hydrolases that "cut and paste" xyloglucan polysaccharides through a transglycosylation process. We have analyzed cohorts of XETs in different plant species to evaluate the substrate specificities of xyloglucan acceptors by using a set of synthetic oligosaccharides obtained by automated glycan assembly. The ability of XETs to incorporate the oligosaccharides into polysaccharides printed as microarrays and into stem sections of Arabidopsis thaliana, beans, and peas was assessed. We found that single xylose substitutions are sufficient for transfer, and xylosylation of the terminal glucose residue is not required by XETs, independent of plant species. To obtain information on the potential xylosylation pattern of the natural acceptor of XETs, that is, the nonreducing end of xyloglucan, we further tested the activity of xyloglucan xylosyl transferase (XXT) 2 on the synthetic xyloglucan oligosaccharides. These data shed light on inconsistencies between previous studies towards determining the acceptor substrate specificities of XETs and have important implications for further understanding plant cell wall polysaccharide synthesis and remodeling.
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Affiliation(s)
- Colin Ruprecht
- Department of Biomolecular Systems, Max Planck Institute of Colloids and Interfaces, Am Mühlenberg 1, 14476, Potsdam, Germany.,Freie Universität Berlin, Institute of Chemistry and Biochemistry, Arnimallee 22, 14195, Berlin, Germany
| | - Pietro Dallabernardina
- Department of Biomolecular Systems, Max Planck Institute of Colloids and Interfaces, Am Mühlenberg 1, 14476, Potsdam, Germany.,Freie Universität Berlin, Institute of Chemistry and Biochemistry, Arnimallee 22, 14195, Berlin, Germany
| | - Peter J Smith
- Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA, 30602, USA
| | - Breeanna R Urbanowicz
- Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA, 30602, USA
| | - Fabian Pfrengle
- Department of Biomolecular Systems, Max Planck Institute of Colloids and Interfaces, Am Mühlenberg 1, 14476, Potsdam, Germany.,Freie Universität Berlin, Institute of Chemistry and Biochemistry, Arnimallee 22, 14195, Berlin, Germany
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13
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Two Variants of a High-Throughput Fluorescent Microplate Assay of Polysaccharide Endotransglycosylases. Appl Biochem Biotechnol 2016; 178:1652-65. [DOI: 10.1007/s12010-015-1973-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Accepted: 12/28/2015] [Indexed: 10/22/2022]
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14
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Simmons TJ, Mohler KE, Holland C, Goubet F, Franková L, Houston DR, Hudson AD, Meulewaeter F, Fry SC. Hetero-trans-β-glucanase, an enzyme unique to Equisetum plants, functionalizes cellulose. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2015; 83:753-69. [PMID: 26185964 PMCID: PMC4950035 DOI: 10.1111/tpj.12935] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Revised: 06/12/2015] [Accepted: 06/24/2015] [Indexed: 05/18/2023]
Abstract
Cell walls are metabolically active components of plant cells. They contain diverse enzymes, including transglycanases (endotransglycosylases), enzymes that 'cut and paste' certain structural polysaccharide molecules and thus potentially remodel the wall during growth and development. Known transglycanase activities modify several cell-wall polysaccharides (xyloglucan, mannans, mixed-linkage β-glucan and xylans); however, no transglycanases were known to act on cellulose, the principal polysaccharide of biomass. We now report the discovery and characterization of hetero-trans-β-glucanase (HTG), a transglycanase that targets cellulose, in horsetails (Equisetum spp., an early-diverging genus of monilophytes). HTG is also remarkable in predominantly catalysing hetero-transglycosylation: its preferred donor substrates (cellulose or mixed-linkage β-glucan) differ qualitatively from its acceptor substrate (xyloglucan). HTG thus generates stable cellulose-xyloglucan and mixed-linkage β-glucan-xyloglucan covalent bonds, and may therefore strengthen ageing Equisetum tissues by inter-linking different structural polysaccharides of the cell wall. 3D modelling suggests that only three key amino acid substitutions (Trp → Pro, Gly → Ser and Arg → Leu) are responsible for the evolution of HTG's unique specificity from the better-known xyloglucan-acting homo-transglycanases (xyloglucan endotransglucosylase/hydrolases; XTH). Among land plants, HTG appears to be confined to Equisetum, but its target polysaccharides are widespread, potentially offering opportunities for enhancing crop mechanical properties, such as wind resistance. In addition, by linking cellulose to xyloglucan fragments previously tagged with compounds such as dyes or indicators, HTG may be useful biotechnologically for manufacturing stably functionalized celluloses, thereby potentially offering a commercially valuable 'green' technology for industrially manipulating biomass.
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Affiliation(s)
- Thomas J Simmons
- The Edinburgh Cell Wall Group, Institute of Molecular Plant Sciences, The University of Edinburgh, Edinburgh, EH9 3BF, UK
| | - Kyle E Mohler
- The Edinburgh Cell Wall Group, Institute of Molecular Plant Sciences, The University of Edinburgh, Edinburgh, EH9 3BF, UK
| | - Claire Holland
- The Edinburgh Cell Wall Group, Institute of Molecular Plant Sciences, The University of Edinburgh, Edinburgh, EH9 3BF, UK
| | - Florence Goubet
- Bayer CropScience NV, Innovation Center, Technologiepark 38, 9052, Gent, Belgium
| | - Lenka Franková
- The Edinburgh Cell Wall Group, Institute of Molecular Plant Sciences, The University of Edinburgh, Edinburgh, EH9 3BF, UK
| | - Douglas R Houston
- Institute of Structural and Molecular Biology, The University of Edinburgh, The King's Buildings, Edinburgh, EH9 3JR, UK
| | - Andrew D Hudson
- Institute of Molecular Plant Sciences, The University of Edinburgh, Edinburgh, EH9 3BF, UK
| | - Frank Meulewaeter
- Bayer CropScience NV, Innovation Center, Technologiepark 38, 9052, Gent, Belgium
| | - Stephen C Fry
- The Edinburgh Cell Wall Group, Institute of Molecular Plant Sciences, The University of Edinburgh, Edinburgh, EH9 3BF, UK
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15
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Harvey DJ. Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: an update for 2009-2010. MASS SPECTROMETRY REVIEWS 2015; 34:268-422. [PMID: 24863367 PMCID: PMC7168572 DOI: 10.1002/mas.21411] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2013] [Revised: 07/16/2013] [Accepted: 07/16/2013] [Indexed: 05/07/2023]
Abstract
This review is the sixth update of the original article published in 1999 on the application of MALDI mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2010. General aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, arrays and fragmentation are covered in the first part of the review and applications to various structural typed constitutes the remainder. The main groups of compound that are discussed in this section are oligo and polysaccharides, glycoproteins, glycolipids, glycosides and biopharmaceuticals. Many of these applications are presented in tabular form. Also discussed are medical and industrial applications of the technique, studies of enzyme reactions and applications to chemical synthesis.
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Affiliation(s)
- David J. Harvey
- Department of BiochemistryOxford Glycobiology InstituteUniversity of OxfordOxfordOX1 3QUUK
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16
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Franková L, Fry SC. A general method for assaying homo- and hetero-transglycanase activities that act on plant cell-wall polysaccharides. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2015; 57:411-428. [PMID: 25641334 DOI: 10.1111/jipb.12337] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2014] [Accepted: 01/26/2015] [Indexed: 06/04/2023]
Abstract
Transglycanases (endotransglycosylases) cleave a polysaccharide (donor-substrate) in mid-chain, and then transfer a portion onto another poly- or oligosaccharide (acceptor-substrate). Such enzymes contribute to plant cell-wall assembly and/or re-structuring. We sought a general method for revealing novel homo- and hetero-transglycanases, applicable to diverse polysaccharides and oligosaccharides, separating transglycanase-generated (3)H-polysaccharides from unreacted (3)H-oligosaccharides--the former immobilized (on filter-paper, silica-gel or glass-fiber), the latter eluted. On filter-paper, certain polysaccharides [e.g. (1→3, 1→4)-β-D-glucans] remained satisfactorily adsorbed when water-washed; others (e.g. pectins) were partially lost. Many oligosaccharides (e.g. arabinan-, galactan-, xyloglucan-based) were successfully eluted in appropriate solvents, but others (e.g. [(3)H]xylohexaitol, [(3)H]mannohexaitol [(3)H]cellohexaitol) remained immobile. On silica-gel, all (3)H-oligosaccharides left an immobile 'ghost' spot (contaminating any (3)H-polysaccharides), which was diminished but not prevented by additives e.g. sucrose or Triton X-100. The best stratum was glass-fiber (GF), onto which the reaction-mixture was dried then washed in 75% ethanol. Washing led to minimal loss or lateral migration of (3)H-polysaccharides if conducted by slow percolation of acidified ethanol. The effectiveness of GF-blotting was well demonstrated for Chara vulgaris trans-β-mannanase. In conclusion, our novel GF-blotting technique efficiently frees transglycanase-generated (3)H-polysaccharides from unreacted (3)H-oligosaccharides, enabling high-throughput screening of multiple postulated transglycanase activities utilising chemically diverse donor- and acceptor-substrates.
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Affiliation(s)
- Lenka Franková
- The Edinburgh Cell Wall Group, Institute of Molecular Plant Sciences, The University of Edinburgh, Daniel Rutherford Building, The King's Buildings, Max Born Crescent, Edinburgh EH9 3BF, UK
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Gray CJ, Weissenborn MJ, Eyers CE, Flitsch SL. Enzymatic reactions on immobilised substrates. Chem Soc Rev 2014; 42:6378-405. [PMID: 23579870 DOI: 10.1039/c3cs60018a] [Citation(s) in RCA: 69] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
This review gives an overview of enzymatic reactions that have been conducted on substrates attached to solid surfaces. Such biochemical reactions have become more important with the drive to miniaturisation and automation in chemistry, biology and medicine. Technical aspects such as choice of solid surface and analytical methods are discussed and examples of enzyme reactions that have been successful on these surfaces are provided.
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Affiliation(s)
- Christopher J Gray
- School of Chemistry & Manchester Institute of Biotechnology, The University of Manchester, 131 Princess Road, Manchester, M1 7DN, UK
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18
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Franková L, Fry SC. Biochemistry and physiological roles of enzymes that 'cut and paste' plant cell-wall polysaccharides. JOURNAL OF EXPERIMENTAL BOTANY 2013; 64:3519-50. [PMID: 23956409 DOI: 10.1093/jxb/ert201] [Citation(s) in RCA: 137] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
The plant cell-wall matrix is equipped with more than 20 glycosylhydrolase activities, including both glycosidases and glycanases (exo- and endo-hydrolases, respectively), which between them are in principle capable of hydrolysing most of the major glycosidic bonds in wall polysaccharides. Some of these enzymes also participate in the 'cutting and pasting' (transglycosylation) of sugar residues-enzyme activities known as transglycosidases and transglycanases. Their action and biological functions differ from those of the UDP-dependent glycosyltransferases (polysaccharide synthases) that catalyse irreversible glycosyl transfer. Based on the nature of the substrates, two types of reaction can be distinguished: homo-transglycosylation (occurring between chemically similar polymers) and hetero-transglycosylation (between chemically different polymers). This review focuses on plant cell-wall-localized glycosylhydrolases and the transglycosylase activities exhibited by some of these enzymes and considers the physiological need for wall polysaccharide modification in vivo. It describes the mechanism of transglycosylase action and the classification and phylogenetic variation of the enzymes. It discusses the modulation of their expression in plants at the transcriptional and translational levels, and methods for their detection. It also critically evaluates the evidence that the enzyme proteins under consideration exhibit their predicted activity in vitro and their predicted action in vivo. Finally, this review suggests that wall-localized glycosylhydrolases with transglycosidase and transglycanase abilities are widespread in plants and play important roles in the mechanism and control of plant cell expansion, differentiation, maturation, and wall repair.
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Affiliation(s)
- Lenka Franková
- Edinburgh Cell Wall Group, Institute of Molecular Plant Sciences, School of Biological Sciences, The University of Edinburgh, The King's Buildings, Mayfield Road, Edinburgh EH9 3JH, UK
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19
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Simmons TJ. Considerations in the search for mixed-linkage (1→3),(1→4)-β-D-glucan-active endotransglycosylases. PLANT SIGNALING & BEHAVIOR 2013; 8:e23835. [PMID: 23425852 PMCID: PMC7030212 DOI: 10.4161/psb.23835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Xyloglucan endotransglucosylase, catalyzed by XTH subfamily members, is thought to play crucial roles in plant cell wall physiology. Recent discovery of endotransglycosylases active on other hemicelluloses extend our understanding of the physiological scope of endotransglycosylation in general. Discovery in Poaceaen XTHs of endotransglycosylases which act on Poaceaen-prevalent hemicelluloses, such as MLG, could reconcile the apparent incongruence between the large size of Poaceaen putative XTH families and the low xyloglucan content of their cell walls. Here, I speculate on hypothetical MLG-active endotransglycosylases and highlight potential hindrances to their discovery. It is suggested that because the location of β-(1→3) bonds within MLG oligosaccharides (MLGOs) could define their ability to act as endotranglycosylase acceptor substrates: a) thorough probing of substrate specificities necessitates the use of MLGOs created using different endo-glycanases; and b) endogenous plant exo-glycosidases, which can hinder endotranglycosylase assays by degrading acceptor substrates, might prove particularly troublesome where MLGOs are concerned.
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Affiliation(s)
- Thomas J. Simmons
- The Edinburgh Cell Wall Group; Institute of Molecular Plant Sciences; School of Biological Sciences; The University of Edinburgh; Edinburgh, U.K
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20
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Mohler KE, Simmons TJ, Fry SC. Mixed-linkage glucan:xyloglucan endotransglucosylase (MXE) re-models hemicelluloses in Equisetum shoots but not in barley shoots or Equisetum callus. THE NEW PHYTOLOGIST 2013; 197:111-122. [PMID: 23078260 DOI: 10.1111/j.1469-8137.2012.04371.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Accepted: 08/31/2012] [Indexed: 05/09/2023]
Abstract
Among land-plant hemicelluloses, xyloglucan is ubiquitous, whereas mixed-linkage (1→3),(1→4)-β-D-glucan (MLG) is confined to the Poales (e.g. cereals) and Equisetales (horsetails). The enzyme MLG:xyloglucan endotransglucosylase (MXE) grafts MLG to xyloglucan. In Equisetum, MXE often exceeds extractable xyloglucan endotransglucosylase (XET) activity; curiously, cereals lack extractable MXE. We investigated whether barley possesses inextractable MXE. Grafting of endogenous MLG or xyloglucan onto exogenous [(3)H]xyloglucan oligosaccharides in vivo indicated MXE and XET action, respectively. Extractable MXE and XET activities were assayed in vitro. MXE and XET actions were both detectable in living Equisetum fluviatile shoots, the MXE : XET ratio increasing with age. However, only XET action was observed in barley coleoptiles, leaves and roots (which all contained MLG) and in E. fluviatile intercalary meristems and callus (which lacked MLG). In E. fluviatile, extractable MXE activity was high in mature shoots, but extremely low in callus and young shoots; in E. arvense strobili, it was undetectable. Barley possesses neither extractable nor inextractable MXE, despite containing both of its substrates and high XET activity. As the Poales are xyloglucan-poor, the role of their abundant endotransglucosylases remains enigmatic. The distribution of MXE action and activity within Equisetum suggests a strengthening role in ageing tissues.
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Affiliation(s)
- Kyle E Mohler
- The Edinburgh Cell Wall Group, Institute of Molecular Plant Sciences, School of Biological Sciences, The University of Edinburgh, The King's Buildings, Edinburgh, EH9 3JH, UK
| | - Thomas J Simmons
- The Edinburgh Cell Wall Group, Institute of Molecular Plant Sciences, School of Biological Sciences, The University of Edinburgh, The King's Buildings, Edinburgh, EH9 3JH, UK
| | - Stephen C Fry
- The Edinburgh Cell Wall Group, Institute of Molecular Plant Sciences, School of Biological Sciences, The University of Edinburgh, The King's Buildings, Edinburgh, EH9 3JH, UK
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21
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Bojarová P, Rosencrantz RR, Elling L, Křen V. Enzymatic glycosylation of multivalent scaffolds. Chem Soc Rev 2013; 42:4774-97. [DOI: 10.1039/c2cs35395d] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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22
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Abstract
Almost all plant cells are surrounded by glycan-rich cell walls, which form much of the plant body and collectively are the largest source of biomass on earth. Plants use polysaccharides for support, defense, signaling, cell adhesion, and as energy storage, and many plant glycans are also important industrially and nutritionally. Understanding the biological roles of plant glycans and the effective exploitation of their useful properties requires a detailed understanding of their structures, occurrence, and molecular interactions. Microarray technology has revolutionized the massively high-throughput analysis of nucleotides, proteins, and increasingly carbohydrates. Using microarrays, the abundance of and interactions between hundreds and thousands of molecules can be assessed simultaneously using very small amounts of analytes. Here we show that carbohydrate microarrays are multifunctional tools for plant research and can be used to map glycan populations across large numbers of samples to screen antibodies, carbohydrate binding proteins, and carbohydrate binding modules and to investigate enzyme activities.
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23
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Pedersen HL, Fangel JU, McCleary B, Ruzanski C, Rydahl MG, Ralet MC, Farkas V, von Schantz L, Marcus SE, Andersen MCF, Field R, Ohlin M, Knox JP, Clausen MH, Willats WGT. Versatile high resolution oligosaccharide microarrays for plant glycobiology and cell wall research. J Biol Chem 2012; 287:39429-38. [PMID: 22988248 PMCID: PMC3501085 DOI: 10.1074/jbc.m112.396598] [Citation(s) in RCA: 175] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2012] [Revised: 09/10/2012] [Indexed: 12/13/2022] Open
Abstract
Microarrays are powerful tools for high throughput analysis, and hundreds or thousands of molecular interactions can be assessed simultaneously using very small amounts of analytes. Nucleotide microarrays are well established in plant research, but carbohydrate microarrays are much less established, and one reason for this is a lack of suitable glycans with which to populate arrays. Polysaccharide microarrays are relatively easy to produce because of the ease of immobilizing large polymers noncovalently onto a variety of microarray surfaces, but they lack analytical resolution because polysaccharides often contain multiple distinct carbohydrate substructures. Microarrays of defined oligosaccharides potentially overcome this problem but are harder to produce because oligosaccharides usually require coupling prior to immobilization. We have assembled a library of well characterized plant oligosaccharides produced either by partial hydrolysis from polysaccharides or by de novo chemical synthesis. Once coupled to protein, these neoglycoconjugates are versatile reagents that can be printed as microarrays onto a variety of slide types and membranes. We show that these microarrays are suitable for the high throughput characterization of the recognition capabilities of monoclonal antibodies, carbohydrate-binding modules, and other oligosaccharide-binding proteins of biological significance and also that they have potential for the characterization of carbohydrate-active enzymes.
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Affiliation(s)
- Henriette L. Pedersen
- From the Department of Plant Biology and Biotechnology, University of Copenhagen, 1871 Frederiksberg, Denmark
| | - Jonatan U. Fangel
- From the Department of Plant Biology and Biotechnology, University of Copenhagen, 1871 Frederiksberg, Denmark
| | - Barry McCleary
- Megazyme International Ireland Ltd., Bray Business Park, Bray, County Wicklow, Ireland
| | - Christian Ruzanski
- the John Innes Centre, Norwich Research Park, Colney, Norwich NR4 7UH, United Kingdom
| | - Maja G. Rydahl
- From the Department of Plant Biology and Biotechnology, University of Copenhagen, 1871 Frederiksberg, Denmark
| | | | - Vladimir Farkas
- the Institute of Chemistry, Centre for Glycobiology, Slovak Academy of Sciences, SK-84538, Bratislava, Slovakia
| | - Laura von Schantz
- the Department of Immunotechnology, Lund University, BMC D13, S-22184 Lund, Sweden
| | - Susan E. Marcus
- the Centre for Plant Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom, and
| | - Mathias C. F. Andersen
- the Center for Nanomedicine and Theranostics and Department of Chemistry, Technical University of Denmark, Building 201, 2800 Kongens Lyngby, Denmark
| | - Rob Field
- the John Innes Centre, Norwich Research Park, Colney, Norwich NR4 7UH, United Kingdom
| | - Mats Ohlin
- the Department of Immunotechnology, Lund University, BMC D13, S-22184 Lund, Sweden
| | - J. Paul Knox
- the Centre for Plant Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, United Kingdom, and
| | - Mads H. Clausen
- the Center for Nanomedicine and Theranostics and Department of Chemistry, Technical University of Denmark, Building 201, 2800 Kongens Lyngby, Denmark
| | - William G. T. Willats
- From the Department of Plant Biology and Biotechnology, University of Copenhagen, 1871 Frederiksberg, Denmark
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24
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Modern Carbohydrate Microarray Biochip Technologies. CHINESE JOURNAL OF ANALYTICAL CHEMISTRY 2012. [DOI: 10.1016/s1872-2040(11)60584-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Ban L, Pettit N, Li L, Stuparu AD, Cai L, Chen W, Guan W, Han W, Wang PG, Mrksich M. Discovery of glycosyltransferases using carbohydrate arrays and mass spectrometry. Nat Chem Biol 2012; 8:769-73. [PMID: 22820418 PMCID: PMC3471075 DOI: 10.1038/nchembio.1022] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2010] [Accepted: 06/08/2012] [Indexed: 01/23/2023]
Abstract
Glycosyltransferases (GTs) catalyze the reaction between an activated sugar donor and an acceptor to form a new glycosidic linkage. GTs are responsible for the assembly of oligosaccharides in vivo and are also important for the in vitro synthesis of these biomolecules. However, the functional identification and characterization of new GTs are both difficult and tedious. This paper describes an approach that combines arrays of reactions on an immobilized array of acceptors with analysis by mass spectrometry to screen putative GTs. A total of 14,280 combinations of GT, acceptor and donor in four buffer conditions were screened and led to the identification and characterization of four new GTs. This work is significant because it provides a label-free method for the rapid functional annotation of putative enzymes.
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Affiliation(s)
- Lan Ban
- Howard Hughes Medical Institute, Northwestern University, Evanston, IL, USA
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Franková L, Fry SC. Trans-α-xylosidase and trans-β-galactosidase activities, widespread in plants, modify and stabilize xyloglucan structures. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2012; 71:45-60. [PMID: 22360414 DOI: 10.1111/j.1365-313x.2012.04966.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Cell-wall components are hydrolysed by numerous plant glycosidase and glycanase activities. We investigated whether plant enzymes also modify xyloglucan structures by transglycosidase activities. Diverse angiosperm extracts exhibited transglycosidase activities that progressively transferred single sugar residues between xyloglucan heptasaccharide (XXXG or its reduced form, XXXGol) molecules, at 16 μM and above, creating octa- to decasaccharides plus smaller products. We measured remarkably high transglycosylation:hydrolysis ratios under optimized conditions. To identify the transferred monosaccharide(s), we devised a dual-labelling strategy in which a neutral radiolabelled oligosaccharide (donor substrate) reacted with an amino-labelled non-radioactive oligosaccharide (acceptor substrate), generating radioactive cationic products. For example, 37 μM [Xyl-³H]XXXG plus 1 mM XXLG-NH₂ generated ³H-labelled cations, demonstrating xylosyl transfer, which exceeded xylosyl hydrolysis 1.6- to 7.3-fold, implying the presence of enzymes that favour transglycosylation. The transferred xylose residues remained α-linked but were relatively resistant to hydrolysis by plant enzymes. Driselase digestion of the products released a trisaccharide (α-[³H]xylosyl-isoprimeverose), indicating that a new xyloglucan repeat unit had been formed. In similar assays, [Gal-³H]XXLG and [Gal-³H]XLLG (but not [Fuc-³H]XXFG) yielded radioactive cations. Thus plants exhibit trans-α-xylosidase and trans-β-galactosidase (but not trans-α-fucosidase) activities that graft sugar residues from one xyloglucan oligosaccharide to another. Reconstructing xyloglucan oligosaccharides in this way may alter oligosaccharin activities or increase their longevity in vivo. Trans-α-xylosidase activity also transferred xylose residues from xyloglucan oligosaccharides to long-chain hemicelluloses (xyloglucan, water-soluble cellulose acetate, mixed-linkage β-glucan, glucomannan and arabinoxylan). With xyloglucan as acceptor substrate, such an activity potentially affects the polysaccharide's suitability as a substrate for xyloglucan endotransglucosylase action and thereby modulates cell expansion. We conclude that certain proteins annotated as glycosidases can function as transglycosidases.
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Affiliation(s)
- Lenka Franková
- Institute of Molecular Plant Sciences, School of Biological Sciences, The University of Edinburgh, The King's Buildings, Mayfield Road, Edinburgh EH9 3JH, UK
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Franková L, Fry SC. Trans-α-xylosidase, a widespread enzyme activity in plants, introduces (1→4)-α-d-xylobiose side-chains into xyloglucan structures. PHYTOCHEMISTRY 2012; 78:29-43. [PMID: 22425285 DOI: 10.1016/j.phytochem.2012.02.003] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2011] [Revised: 02/02/2012] [Accepted: 02/03/2012] [Indexed: 05/31/2023]
Abstract
Angiosperms possess a retaining trans-α-xylosidase activity that catalyses the inter-molecular transfer of xylose residues between xyloglucan structures. To identify the linkage of the newly transferred α-xylose residue, we used [Xyl-(3)H]XXXG (xyloglucan heptasaccharide) as donor substrate and reductively-aminated xyloglucan oligosaccharides (XGO-NH(2)) as acceptor. Asparagus officinalis enzyme extracts generated cationic radioactive products ([(3)H]Xyl·XGO-NH(2)) that were Driselase-digestible to a neutral trisaccharide containing an α-[(3)H]xylose residue. After borohydride reduction, the trimer exhibited high molybdate-affinity, indicating xylobiosyl-(1→6)-glucitol rather than a di-xylosylated glucitol. Thus the trans-α-xylosidase had grafted an additional α-[(3)H]xylose residue onto the xylose of an isoprimeverose unit. The trisaccharide was rapidly acetolysed to an α-[(3)H]xylobiose, confirming the presence of an acetolysis-labile (1→6)-bond. The α-[(3)H]xylobiitol formed by reduction of this α-[(3)H]xylobiose had low molybdate-affinity, indicating a (1→2) or (1→4) linkage. In NaOH, the α-[(3)H]xylobiose underwent alkaline peeling at the moderate rate characteristic of a (1→4)-disaccharide. Finally, we synthesised eight non-radioactive xylobioses [α and β; (1↔1), (1→2), (1→3) and (1→4)] and found that the [(3)H]xylobiose co-chromatographed only with (1→4)-α-xylobiose. We conclude that Asparagus trans-α-xylosidase activity generates a novel xyloglucan building block, α-d-Xylp-(1→4)-α-d-Xylp-(1→6)-d-Glc (abbreviation: 'V'). Modifying xyloglucan structures in this way may alter oligosaccharin activities, or change their suitability as acceptor substrates for xyloglucan endotransglucosylase (XET) activity.
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Affiliation(s)
- Lenka Franková
- The Edinburgh Cell Wall Group, Institute of Molecular Plant Sciences, School of Biological Sciences, The University of Edinburgh, The King's Buildings, Mayfield Road, Edinburgh EH9 3JH, UK
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Abstract
Plant cell walls have the remarkable property of combining extreme tensile strength with extensibility. The maintenance of such an exoskeleton creates nontrivial challenges for the plant cell: How can it control cell wall assembly and remodeling during growth while maintaining mechanical integrity? How can it deal with cell wall damage inflicted by herbivores, pathogens, or abiotic stresses? These processes likely require mechanisms to keep the cell informed about the status of the cell wall. In yeast, a cell wall integrity (CWI) signaling pathway has been described in great detail; in plants, the existence of CWI signaling has been demonstrated, but little is known about the signaling pathways involved. In this review, we first describe cell wall-related processes that may require or can be targets of CWI signaling and then discuss our current understanding of CWI signaling pathways and future prospects in this emerging field of plant biology.
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Affiliation(s)
- Sebastian Wolf
- Institut Jean-Pierre Bourgin, UMR 1318 INRA/AgroParisTech, Versailles Cedex, France.
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Abstract
In the last decade, glycan microarrays have revolutionized the analysis of the specificity of glycan-binding proteins (GBPs), providing information that simultaneously illuminates the biology mediated by them and decodes the informational content of the glycome. Numerous methods have emerged for arraying glycans in a "chip" format, and glycan libraries have been assembled that address the diversity of the human glycome. Such arrays have been successfully used for analysis of GBPs, which mediate mammalian biology, host-pathogen interactions, and immune recognition of glycans relevant to vaccine production and cancer antigens. This review covers the development of glycan microarrays and applications that have provided insights into the roles of mammalian and microbial GBPs.
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Affiliation(s)
- Cory D Rillahan
- Department of Chemical Physiology, The Scripps Research Institute, La Jolla, California 92037, USA.
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Catalytic properties of the Gas family β-(1,3)-glucanosyltransferases active in fungal cell-wall biogenesis as determined by a novel fluorescent assay. Biochem J 2011; 438:275-82. [DOI: 10.1042/bj20110405] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
BGTs [β-(1,3)-glucanosyltransglycosylases; EC 2.4.1.-] of the GH72 (family 72 of glycosylhydrolases) are GPI (glycosylphosphatidylinositol)-anchored proteins that play an important role in the biogenesis of fungal cell walls. They randomly cleave glycosidic linkages in β-(1,3)-glucan chains and ligate the polysaccharide portions containing newly formed reducing ends to C3(OH) at non-reducing ends of other β-(1,3)-glucan molecules. We have developed a sensitive fluorescence-based method for the assay of transglycosylating activity of GH72 enzymes. In the new assay, laminarin [β-(1,3)-glucan] is used as the glucanosyl donor and LamOS (laminarioligosaccharides) fluorescently labelled with SR (sulforhodamine) serve as the acceptors. The new fluorescent assay was employed for partial biochemical characterization of the heterologously expressed Gas family proteins from the yeast Saccharomyces cerevisiae. All the Gas enzymes specifically used laminarin as the glucanosyl donor and a SR–LamOS of DP (degree of polymerization) ≥5 as the acceptors. Gas proteins expressed in distinct stages of the yeast life cycle showed differences in their pH optima. Gas1p and Gas5p, which are expressed during vegetative growth, had the highest activity at pH 4.5 and 3.5 respectively, whereas the sporulation-specific Gas2p and Gas4p were most active between pH 5 and 6. The novel fluorescent assay provides a suitable tool for the screening of potential glucanosyltransferases or their inhibitors.
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Franková L, Fry SC. Phylogenetic variation in glycosidases and glycanases acting on plant cell wall polysaccharides, and the detection of transglycosidase and trans-β-xylanase activities. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2011; 67:662-81. [PMID: 21554451 DOI: 10.1111/j.1365-313x.2011.04625.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Wall polysaccharide chemistry varies phylogenetically, suggesting a need for variation in wall enzymes. Although plants possess the genes for numerous putative enzymes acting on wall carbohydrates, the activities of the encoded proteins often remain conjectural. To explore phylogenetic differences in demonstrable enzyme activities, we extracted proteins from 57 rapidly growing plant organs with three extractants, and assayed their ability to act on six oligosaccharides 'modelling' selected cell-wall polysaccharides. Based on reaction products, we successfully distinguished exo- and endo-hydrolases and found high taxonomic variation in all hydrolases screened: β-D-xylosidase, endo-(1→4)-β-D-xylanase, β-D-mannosidase, endo-(1→4)-β-D-mannanase, α-D-xylosidase, β-D-galactosidase, α-L-arabinosidase and α-L-fucosidase. The results, as GHATAbase, a searchable compendium in Excel format, also provide a compilation for selecting rich sources of enzymes acting on wall carbohydrates. Four of the hydrolases were accompanied, sometimes exceeded, by transglycosylase activities, generating products larger than the substrate. For example, during β-xylosidase assays on (1→4)-β-D-xylohexaose (Xyl₆), Marchantia, Selaginella and Equisetum extracts gave negligible free xylose but approximately equimolar Xyl₅ and Xyl₇, indicating trans-β-xylosidase activity, also found in onion, cereals, legumes and rape. The yield of Xyl₉ often exceeded that of Xyl₇₋₈, indicating that β-xylanase was accompanied by an endotransglycosylase activity, here called trans-β-xylanase, catalysing the reaction 2Xyl₆ → Xyl₃ + Xyl₉. Similar evidence also revealed trans-α-xylosidase, trans-α-arabinosidase and trans-α-arabinanase activities acting on xyloglucan oligosaccharides and (1→5)-α-L-arabino-oligosaccharides. In conclusion, diverse plants differ dramatically in extractable enzymes acting on wall carbohydrate, reflecting differences in wall polysaccharide composition. Besides glycosidase and glycanase activities, five new transglycosylase activities were detected. We propose that such activities function in the assembly and re-structuring of the wall matrix.
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Affiliation(s)
- Lenka Franková
- The Edinburgh Cell Wall Group, Institute of Molecular Plant Sciences, School of Biological Sciences, The University of Edinburgh, The King's Buildings, Mayfield Road, Edinburgh EH93JH, UK
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Effect of the label of oligosaccharide acceptors on the kinetic parameters of nasturtium seed xyloglucan endotransglycosylase (XET). Carbohydr Res 2011; 346:357-61. [DOI: 10.1016/j.carres.2010.09.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2010] [Revised: 08/19/2010] [Accepted: 09/02/2010] [Indexed: 11/20/2022]
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Stratilová E, Ait-Mohand F, Rehulka P, Garajová S, Flodrová D, Rehulková H, Farkas V. Xyloglucan endotransglycosylases (XETs) from germinating nasturtium (Tropaeolum majus) seeds: isolation and characterization of the major form. PLANT PHYSIOLOGY AND BIOCHEMISTRY : PPB 2010; 48:207-215. [PMID: 20153658 DOI: 10.1016/j.plaphy.2010.01.016] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2009] [Revised: 01/13/2010] [Accepted: 01/16/2010] [Indexed: 05/28/2023]
Abstract
Five forms of xyloglucan endotransglycosylase/hydrolase (XTH) differing in their isoelectric points (pI) were detected in crude extracts from germinating nasturtium seeds. Without further fractionation, all five forms behaved as typical endotransglycosylases since they exhibited only transglycosylating (XET) activity and no xyloglucan-hydrolysing (XEH) activity. They all were glycoproteins with identical molecular mass, and deglycosylation led to a decrease in molecular mass from approximately 29 to 26.5 kDa. The major enzyme form having pI 6.3, temporarily designated as TmXET(6.3), was isolated and characterized. Molecular and biochemical properties of TmXET(6.3) confirmed its distinction from the XTHs described previously from nasturtium. The enzyme exhibited broad substrate specificity by transferring xyloglucan or hydroxyethylcellulose fragments not only to oligoxyloglucosides and cello-oligosaccharides but also to oligosaccharides derived from beta-(1,4)-d-glucuronoxylan, beta-(1,6)-d-glucan, mixed-linkage beta-(1,3; 1,4)-d-glucan and at a relatively low rate also to beta-(1,3)-gluco-oligosaccharides. The transglycosylating activity with xyloglucan as donor and cello-oligosaccharides as acceptors represented 4.6%, with laminarioligosaccharides 0.23%, with mixed-linkage beta-(1,3; 1,4)-d-gluco-oligosaccharides 2.06%, with beta-(1,4)-d-glucuronoxylo-oligosaccharides 0.31% and with beta-(1,6)-d-gluco-oligosaccharides 0.69% of that determined with xyloglucan oligosaccharides as acceptors. Based on the sequence homology of tryptic fragments with the sequences of known XTHs, the TmXET(6.3) was classified into group II of the XTH phylogeny of glycoside hydrolase family GH16.
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Affiliation(s)
- Eva Stratilová
- Institute of Chemistry, Center for Glycomics, Slovak Academy of Sciences, Dúbravská cesta 9, SK-84538 Bratislava, Slovakia
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