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Xiao Y, Dong S, Liu YJ, You C, Feng Y, Cui Q. Key roles of β-glucosidase BglA for the catabolism of both laminaribiose and cellobiose in the lignocellulolytic bacterium Clostridium thermocellum. Int J Biol Macromol 2023; 250:126226. [PMID: 37558019 DOI: 10.1016/j.ijbiomac.2023.126226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Revised: 07/31/2023] [Accepted: 08/06/2023] [Indexed: 08/11/2023]
Abstract
The thermophilic bacterium Clostridium thermocellum efficiently degrades polysaccharides into oligosaccharides. The metabolism of β-1,4-linked cello-oligosaccharides is initiated by three enzymes, i.e., the cellodextrin phosphorylase (Cdp), the cellobiose phosphorylase (Cbp), and the β-glucosidase A (BglA), in C. thermocellum. In comparison, how the oligosaccharides containing other kinds of linkage are utilized is rarely understood. In this study, we found that BglA could hydrolyze the β-1,3-disaccharide laminaribiose with much higher activity than that against the β-1,4-disaccharide cellobiose. The structural basis of the substrate specificity was analyzed by crystal structure determination and molecular docking. Genetic deletions of BglA and Cbp, respectively, and enzymatic analysis of cell extracts demonstrated that BglA is the key enzyme responsible for laminaribiose metabolism. Furthermore, the deletion of BglA can suppress the expression of Cbp and the deletion of Cbp can up-regulate the expression of BglA, indicating that BglA and Cbp have cross-regulation and BglA is also critical for cellobiose metabolism. These insights pave the way for both a fundamental understanding of metabolism and regulation in C. thermocellum and emphasize the importance of the degradation and utilization of polysaccharides containing β-1,3-linked glycosidic bonds in lignocellulose biorefinery.
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Affiliation(s)
- Yan Xiao
- CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic Biology, Shandong Engineering Laboratory of Single Cell Oil, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China; Shandong Energy Institute, Qingdao, China; Qingdao New Energy Shandong Laboratory, Qingdao, China; Dalian National Laboratory for Clean Energy, Qingdao, China; University of Chinese Academy of Sciences, Beijing, China
| | - Sheng Dong
- CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic Biology, Shandong Engineering Laboratory of Single Cell Oil, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China; Shandong Energy Institute, Qingdao, China; Qingdao New Energy Shandong Laboratory, Qingdao, China; Dalian National Laboratory for Clean Energy, Qingdao, China; University of Chinese Academy of Sciences, Beijing, China
| | - Ya-Jun Liu
- CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic Biology, Shandong Engineering Laboratory of Single Cell Oil, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China; Shandong Energy Institute, Qingdao, China; Qingdao New Energy Shandong Laboratory, Qingdao, China; Dalian National Laboratory for Clean Energy, Qingdao, China; University of Chinese Academy of Sciences, Beijing, China
| | - Chun You
- Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, China
| | - Yingang Feng
- CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic Biology, Shandong Engineering Laboratory of Single Cell Oil, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China; Shandong Energy Institute, Qingdao, China; Qingdao New Energy Shandong Laboratory, Qingdao, China; Dalian National Laboratory for Clean Energy, Qingdao, China; University of Chinese Academy of Sciences, Beijing, China.
| | - Qiu Cui
- CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic Biology, Shandong Engineering Laboratory of Single Cell Oil, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, China; Shandong Energy Institute, Qingdao, China; Qingdao New Energy Shandong Laboratory, Qingdao, China; Dalian National Laboratory for Clean Energy, Qingdao, China; University of Chinese Academy of Sciences, Beijing, China.
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2
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Kido Y, Saburi W, Nagura T, Mori H. Hydrolysis-transglycosylation of sucrose and production of β-(2→1)-fructan by inulosucrase from Neobacillus drentensis 57N. Biosci Biotechnol Biochem 2023; 87:1169-1182. [PMID: 37491698 DOI: 10.1093/bbb/zbad100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Accepted: 07/19/2023] [Indexed: 07/27/2023]
Abstract
Inulin, β-(2→1)-fructan, is a beneficial polysaccharide used as a functional food ingredient. Microbial inulosucrases (ISs), catalyzing β-(2→1)-transfructosylation, produce β-(2→1)-fructan from sucrose. In this study, we identified a new IS (NdIS) from the soil isolate, Neobacillus drentensis 57N. Sequence analysis revealed that, like other Bacillaceae ISs, NdIS consists of a glycoside hydrolase family 68 domain and shares most of the 1-kestose-binding residues of the archaeal IS, InuHj. Native and recombinant NdIS were characterized. NdIS is a homotetramer. It does not require calcium for activity. High performance liquid chromatography and 13C-nuclear magnetic resonance indicated that NdIS catalyzed the hydrolysis and β-(2→1)-transfructosylation of sucrose to synthesize β-(2→1)-fructan with chain lengths of 42 or more residues. The rate dependence on sucrose concentration followed hydrolysis-transglycosylation kinetics, and a 50% transglycosylation ratio was obtained at 344 m m sucrose. These results suggest that transfructosylation from sucrose to β-(2→1)-fructan occurs predominantly to elongate the fructan chain because sucrose is an unfavorable acceptor.
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Affiliation(s)
- Yusuke Kido
- Research Center, Nippon Beet Sugar Mfg. Co., Ltd., Obihiro, Hokkaido, Japan
- Research Faculty of Agriculture, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Wataru Saburi
- Research Faculty of Agriculture, Hokkaido University, Sapporo, Hokkaido, Japan
| | - Taizo Nagura
- Research Center, Nippon Beet Sugar Mfg. Co., Ltd., Obihiro, Hokkaido, Japan
| | - Haruhide Mori
- Research Faculty of Agriculture, Hokkaido University, Sapporo, Hokkaido, Japan
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3
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Ota T, Saburi W, Komba S, Mori H. Chemical synthesis of oligosaccharide derivatives with partial structure of β1-3/1-6 glucan, using monomeric units for the formation of β1-3 and β1-6 glucosidic linkages. Biosci Biotechnol Biochem 2023; 87:1111-1121. [PMID: 37407435 DOI: 10.1093/bbb/zbad093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2023] [Accepted: 06/29/2023] [Indexed: 07/07/2023]
Abstract
β1-3/1-6 Glucans, known for their diverse structures, comprise a β1-3-linked main chain and β1-6-linked short branches. Laminarin, a β1-3/1-6 glucan extracted from brown seaweed, for instance, includes β1-6 linkages even in the main chain. The diverse structures provide various beneficial functions for the glucan. To investigate the relationship between structure and functionality, and to enable the characterization of β1-3/1-6 glucan-metabolizing enzymes, oligosaccharides containing the exact structures of β1-3/1-6 glucans are required. We synthesized the monomeric units for the synthesis of β1-3/1-6 mixed-linked glucooligosaccharides. 2-(Trimethylsilyl)ethyl 2-O-benzoyl-4,6-O-benzylidene-β-d-glucopyranoside served as an acceptor in the formation of β1-3 linkages. Phenyl 2-O-benzoyl-4,6-O-benzylidene-3-O-(tert-butyldiphenylsilyl)-1-thio-β-d-glucopyranoside and phenyl 2,3-di-O-benzoyl-4,6-di-O-levulinyl-1-thio-β-d-glucopyranoside acted as donors, synthesizing acceptors suitable for the formation of β1-3- and β1-6-linkages, respectively. These were used to synthesize a derivative of Glcβ1-6Glcβ1-3Glcβ1-3Glc, demonstrating that the proposed route can be applied to synthesize the main chain of β-glucan, with the inclusion of both β1-3 and β1-6 linkages.
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Affiliation(s)
- Tomoya Ota
- Research Faculty of Agriculture, Hokkaido University, Sapporo, Japan
| | - Wataru Saburi
- Research Faculty of Agriculture, Hokkaido University, Sapporo, Japan
| | - Shiro Komba
- Institute of Food Research, National Agriculture and Food Research Organization, Tsukuba, Japan
| | - Haruhide Mori
- Research Faculty of Agriculture, Hokkaido University, Sapporo, Japan
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Kojima K, Sunagawa N, Mikkelsen NE, Hansson H, Karkehabadi S, Samejima M, Sandgren M, Igarashi K. Comparison of Glycoside Hydrolase family 3 β-xylosidases from basidiomycetes and ascomycetes reveals evolutionarily distinct xylan degradation systems. J Biol Chem 2022; 298:101670. [PMID: 35120929 PMCID: PMC8913315 DOI: 10.1016/j.jbc.2022.101670] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 01/27/2022] [Accepted: 01/28/2022] [Indexed: 11/28/2022] Open
Abstract
Xylan is the most common hemicellulose in plant cell walls, though the structure of xylan polymers differs between plant species. Here, to gain a better understanding of fungal xylan degradation systems, which can enhance enzymatic saccharification of plant cell walls in industrial processes, we conducted a comparative study of two glycoside hydrolase family 3 (GH3) β-xylosidases (Bxls), one from the basidiomycete Phanerochaete chrysosporium (PcBxl3), and the other from the ascomycete Trichoderma reesei (TrXyl3A). A comparison of the crystal structures of the two enzymes, both with saccharide bound at the catalytic center, provided insight into the basis of substrate binding at each subsite. PcBxl3 has a substrate-binding pocket at subsite -1, while TrXyl3A has an extra loop that contains additional binding subsites. Furthermore, kinetic experiments revealed that PcBxl3 degraded xylooligosaccharides faster than TrXyl3A, while the KM values of TrXyl3A were lower than those of PcBxl3. The relationship between substrate specificity and degree of polymerization of substrates suggested that PcBxl3 preferentially degrades xylobiose (X2), while TrXyl3A degrades longer xylooligosaccharides. Moreover, docking simulation supported the existence of extended positive subsites of TrXyl3A in the extra loop located at the N-terminus of the protein. Finally, phylogenetic analysis suggests that wood-decaying basidiomycetes use Bxls such as PcBxl3 that act efficiently on xylan structures from woody plants, whereas molds use instead Bxls that efficiently degrade xylan from grass. Our results provide added insights into fungal efficient xylan degradation systems.
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Affiliation(s)
- Keisuke Kojima
- Department of Biomaterial Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Naoki Sunagawa
- Department of Biomaterial Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Nils Egil Mikkelsen
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, Uppsala SE-750 07, Sweden
| | - Henrik Hansson
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, Uppsala SE-750 07, Sweden
| | - Saeid Karkehabadi
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, Uppsala SE-750 07, Sweden
| | - Masahiro Samejima
- Department of Biomaterial Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan; Faculty of Engineering, Shinshu University, 4-17-1, Wakasato, Nagano 380-8533, Japan
| | - Mats Sandgren
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, Uppsala SE-750 07, Sweden
| | - Kiyohiko Igarashi
- Department of Biomaterial Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan; VTT Technical Research Centre of Finland, PO Box 1000, Tietotie 2, Espoo FI-02044 VTT, Finland.
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Berrocal C, Chico H, Carranza E, Vega R. Desirability function for optimization of the synthesis of high-panose isomaltooligosaccharides from maltose catalyzed by a novel commercial enzyme preparation from Aspergillus niger. Biochem Eng J 2021. [DOI: 10.1016/j.bej.2021.108003] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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Nidetzky B, Zhong C. Phosphorylase-catalyzed bottom-up synthesis of short-chain soluble cello-oligosaccharides and property-tunable cellulosic materials. Biotechnol Adv 2020; 51:107633. [PMID: 32966861 DOI: 10.1016/j.biotechadv.2020.107633] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2020] [Revised: 08/23/2020] [Accepted: 09/06/2020] [Indexed: 12/13/2022]
Abstract
Cellulose-based materials are produced industrially in countless varieties via top-down processing of natural lignocellulose substrates. By contrast, cellulosic materials are only rarely prepared via bottom up synthesis and oligomerization-induced self-assembly of cellulose chains. Building up a cellulose chain via precision polymerization is promising, however, for it offers tunability and control of the final chemical structure. Synthetic cellulose derivatives with programmable material properties might thus be obtained. Cellodextrin phosphorylase (CdP; EC 2.4.1.49) catalyzes iterative β-1,4-glycosylation from α-d-glucose 1-phosphate, with the ability to elongate a diversity of acceptor substrates, including cellobiose, d-glucose and a range of synthetic glycosides having non-sugar aglycons. Depending on the reaction conditions leading to different degrees of polymerization (DP), short-chain soluble cello-oligosaccharides (COS) or insoluble cellulosic materials are formed. Here, we review the characteristics of CdP as bio-catalyst for synthetic applications and show advances in the enzymatic production of COS and reducing end-modified, tailored cellulose materials. Recent studies reveal COS as interesting dietary fibers that could provide a selective prebiotic effect. The bottom-up synthesized celluloses involve chains of DP ≥ 9, as precipitated in solution, and they form ~5 nm thick sheet-like crystalline structures of cellulose allomorph II. Solvent conditions and aglycon structures can direct the cellulose chain self-assembly towards a range of material architectures, including hierarchically organized networks of nanoribbons, or nanorods as well as distorted nanosheets. Composite materials are also formed. The resulting materials can be useful as property-tunable hydrogels and feature site-specific introduction of functional and chemically reactive groups. Therefore, COS and cellulose obtained via bottom-up synthesis can expand cellulose applications towards product classes that are difficult to access via top-down processing of natural materials.
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Affiliation(s)
- 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.
| | - Chao Zhong
- Institute of Biotechnology and Biochemical Engineering, Graz University of Technology, NAWI Graz, Petersgasse 12, Graz 8010, Austria
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Prawisut A, Choknud S, Ketudat Cairns JR. Expression of rice β-exoglucanase II (OsExoII) in Escherichia coli, purification, and characterization. Protein Expr Purif 2020; 175:105708. [PMID: 32738438 DOI: 10.1016/j.pep.2020.105708] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 06/10/2020] [Accepted: 07/10/2020] [Indexed: 11/15/2022]
Abstract
Enzymes involved in β-glucan breakdown in plants include endoglucanases, exoglucanases and β-glucosidases. Glycoside hydrolase family 3 (GH3) exoglucanases from barley and maize and a few plant GH3 β-glucosidases have been characterized, but none from rice. A few of these enzymes have been expressed in recombinant yeast and plant systems, but bacterial expression of plant GH3 enzymes has not been successful. We expressed the rice GH3 exoglucanase OsExo2 in Escherichia coli as a thioredoxin fusion protein, while other active plant GH3 enzymes could not be produced in this system. The protein was purified over 2000-fold in three chromatographic steps. The enzyme hydrolyzed β-1,3- and β-1,4-linked oligosaccharides and polysaccharides, consistent with a role in cell wall remodeling. Of the oligosaccharides tested, it had highest catalytic efficiency toward laminaritriose, (apparent kcat/Km = 37.7 mM-1s-1). Among polysaccharides, OsExoII hydrolyzed barley mixed β-glucan and laminarin with similar efficiencies (apparent kcat/Km = 3.7 and 3.4 mL mg-1 s-1, respectively), but achieved its highest apparent kcat with lichenan (2.9 s-1). OsExoII was found to be stimulated by ethylene glycol, which increased the apparent kcat and decreased the Km and was transglycosylated. These results imply that E. coli expression may be successful for certain plant GH3 enzymes and OsExoII may be a useful enzyme for application to glycoside production.
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Affiliation(s)
- Akkarawit Prawisut
- School of Chemistry, Institute of Science and Center for Biomolecular Structure, Function and Application, Suranaree University of Technology, 111 University Avenue, Muang District, Nakhon Ratchasima, 30000, Thailand
| | - Sunaree Choknud
- School of Chemistry, Institute of Science and Center for Biomolecular Structure, Function and Application, Suranaree University of Technology, 111 University Avenue, Muang District, Nakhon Ratchasima, 30000, Thailand
| | - James R Ketudat Cairns
- School of Chemistry, Institute of Science and Center for Biomolecular Structure, Function and Application, Suranaree University of Technology, 111 University Avenue, Muang District, Nakhon Ratchasima, 30000, Thailand.
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Pauchet Y, Ruprecht C, Pfrengle F. Analyzing the Substrate Specificity of a Class of Long-Horned-Beetle-Derived Xylanases by Using Synthetic Arabinoxylan Oligo- and Polysaccharides. Chembiochem 2020; 21:1517-1525. [PMID: 31850611 PMCID: PMC7317733 DOI: 10.1002/cbic.201900687] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Indexed: 12/23/2022]
Abstract
Xylophagous long-horned beetles thrive in challenging environments. To access nutrients, they secrete plant-cell-wall-degrading enzymes in their gut fluid; among them are cellulases of the subfamily 2 of glycoside hydrolase family 5 (GH5_2). Recently, we discovered that several beetle-derived GH5_2s use xylan as a substrate instead of cellulose, which is unusual for this family of enzymes. Here, we analyze the substrate specificity of a GH5_2 xylanase from the beetle Apriona japonica (AJAGH5_2-1) using commercially available substrates and synthetic arabinoxylan oligo- and polysaccharides. We demonstrate that AJAGH5_2-1 processes arabinoxylan polysaccharides in a manner distinct from classical xylanase families such as GH10 and GH11. AJAGH5_2-1 is active on long oligosaccharides and cleaves at the non-reducing end of a substituted xylose residue (position +1) only if: 1) three xylose residues are present upstream and downstream of the cleavage site, and 2) xylose residues at positions -1, -2, +2 and +3 are not substituted.
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Affiliation(s)
- Yannick Pauchet
- Department of Entomology, Max Planck Institute for Chemical Ecology, Hans-Knoell-Strasse 8, 07745, Jena, Germany
| | - Colin Ruprecht
- Department of Biomolecular Systems, Max Planck Institute of Colloids and Interfaces, Am Mühlenberg 1, 14476, Potsdam, Germany
| | - Fabian Pfrengle
- Department of Biomolecular Systems, Max Planck Institute of Colloids and Interfaces, Am Mühlenberg 1, 14476, Potsdam, Germany.,Institute of Chemistry and Biochemistry, Freie Universität Berlin, Takustrasse 3, 14195, Berlin, Germany
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Jeon BM, Baek JI, Kim MS, Kim SC, Cui CH. Characterization of a Novel Ginsenoside MT1 Produced by an Enzymatic Transrhamnosylation of Protopanaxatriol-Type Ginsenosides Re. Biomolecules 2020; 10:E525. [PMID: 32244263 PMCID: PMC7226242 DOI: 10.3390/biom10040525] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2020] [Revised: 03/25/2020] [Accepted: 03/26/2020] [Indexed: 12/13/2022] Open
Abstract
BACKGROUND Ginsenosides, triterpene saponins of Panax species, are considered the main active ingredients responsible for various pharmacological activities. Herein, a new protopanaxatriol-type ginsenoside called "ginsenoside MT1" is described; it was accidentally found among the enzymatic conversion products of ginsenoside Re. METHOD We analyzed the conversion mechanism and found that recombinant β-glucosidase (MT619) transglycosylated the outer rhamnopyranoside of Re at the C-6 position to glucopyranoside at C-20. The production of MT1 by trans-rhamnosylation was optimized and pure MT1 was obtained through various chromatographic processes. RESULTS The structure of MT1 was elucidated based on spectral data: (20S)-3β,6α,12β,20-tetrahydroxydammarene-20-O-[α-L-rhamnopyranosyl(1→2)-β-D-glucopyranoside]. This dammarane-type triterpene saponin was confirmed as a novel compound. CONCLUSION Based on the functions of ginsenosides with similar structures, we believe that this ginsenoside MT1 may have great potential in the development of nutraceutical, pharmaceutical or cosmeceutical products.
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Affiliation(s)
- Byeong-Min Jeon
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, 291 Daehak-Ro, Yuseong-Gu, Daejeon 305-701, Korea
| | - Jong-In Baek
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, 291 Daehak-Ro, Yuseong-Gu, Daejeon 305-701, Korea
| | - Min-Sung Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, 291 Daehak-Ro, Yuseong-Gu, Daejeon 305-701, Korea
| | - Sun-Chang Kim
- Department of Biological Sciences, Korea Advanced Institute of Science and Technology, 291 Daehak-Ro, Yuseong-Gu, Daejeon 305-701, Korea
- Intelligent Synthetic Biology Center, 291 Daehak-Ro, Yuseong-Gu, Daejeon 305-701, Korea
- KAIST Institute for Biocentury, Korea Advanced Institute of Science and Technology, 291 Daehak-Ro, Yuseong-Gu, Daejeon 305-701, Korea
| | - Chang-Hao Cui
- Intelligent Synthetic Biology Center, 291 Daehak-Ro, Yuseong-Gu, Daejeon 305-701, Korea
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Kang L, Zhang X, Wang R, Liu C, Yi L, Liu Z, Zhang Z, Yuan S. β-Glucosidase BGL1 from Coprinopsis cinerea Exhibits a Distinctive Hydrolysis and Transglycosylation Activity for Application in the Production of 3-O-β-d-Gentiobiosyl-d-laminarioligosaccharides. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2019; 67:10744-10755. [PMID: 31525900 DOI: 10.1021/acs.jafc.9b04488] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We previously reported that β-glucosidase BGL1 at low concentration (15 μg mL-1) from Coprinopsis cinerea exhibited hydrolytic activity only toward laminarioligosaccharides but not toward cellooligosaccharides and gentiobiose. This study shows that BGL1 at high concentration (200 μg mL-1) also hydrolyzed cellobiose and gentiobiose, which accounted for only 0.83 and 2.05% of its activity toward laminaribiose, respectively. Interestingly, BGL1 at low concentration (1.5 μg mL-1) showed transglycosylation but BGL1 at high concentration (200 μg mL-1) did not. BGL1 utilizes only laminarioligosaccharides but not glucose, gentiobiose, and cellobiose to synthesize the higher oligosaccharides. BGL1 transferred one glucosyl residue from substrate laminarioligosaccharide to another laminarioligosaccharide as an acceptor in a β(1 → 3) or β(1 → 6) fashion to produce higher laminarioligosaccharides or 3-O-β-d-gentiobiosyl-d-laminarioligosaccharides. The BGL1-digested laminaritriose exhibited approximately 90% enhancement in the anti-oxidant activity compared to that of untreated laminaritriose, implying a potential application of BGL1-based transglycosylation for the production of high value-added rare oligosaccharides.
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Affiliation(s)
- Liqin Kang
- Jiangsu Key Laboratory for Microbes and Microbial Functional Genomics, Jiangsu Engineering and Technology Research Center for Industrialization of Microbial Resources, College of Life Science , Nanjing Normal University , Nanjing 210023 , PR China
| | - Xingwei Zhang
- Jiangsu Key Laboratory for Microbes and Microbial Functional Genomics, Jiangsu Engineering and Technology Research Center for Industrialization of Microbial Resources, College of Life Science , Nanjing Normal University , Nanjing 210023 , PR China
| | - Rui Wang
- Jiangsu Key Laboratory for Microbes and Microbial Functional Genomics, Jiangsu Engineering and Technology Research Center for Industrialization of Microbial Resources, College of Life Science , Nanjing Normal University , Nanjing 210023 , PR China
| | - Cuicui Liu
- Jiangsu Key Laboratory for Microbes and Microbial Functional Genomics, Jiangsu Engineering and Technology Research Center for Industrialization of Microbial Resources, College of Life Science , Nanjing Normal University , Nanjing 210023 , PR China
| | - Lin Yi
- Jiangsu Key Laboratory of Translational Research and Therapy for Neuro-Psycho-Diseases and College of Pharmaceutical Sciences , Soochow University , Suzhou , Jiangsu , 215021 , China
| | - Zhonghua Liu
- Jiangsu Key Laboratory for Microbes and Microbial Functional Genomics, Jiangsu Engineering and Technology Research Center for Industrialization of Microbial Resources, College of Life Science , Nanjing Normal University , Nanjing 210023 , PR China
| | - Zhenqing Zhang
- Jiangsu Key Laboratory of Translational Research and Therapy for Neuro-Psycho-Diseases and College of Pharmaceutical Sciences , Soochow University , Suzhou , Jiangsu , 215021 , China
| | - Sheng Yuan
- Jiangsu Key Laboratory for Microbes and Microbial Functional Genomics, Jiangsu Engineering and Technology Research Center for Industrialization of Microbial Resources, College of Life Science , Nanjing Normal University , Nanjing 210023 , PR China
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Kovalová T, Koval T, Benešová E, Vodicková P, Spiwok V, Lipovová P, Dohnálek J. Active site complementation and hexameric arrangement in the GH family 29; a structure-function study of α-l-fucosidase isoenzyme 1 from Paenibacillus thiaminolyticus. Glycobiology 2019; 29:59-73. [PMID: 30544181 DOI: 10.1093/glycob/cwy078] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Accepted: 08/22/2018] [Indexed: 12/12/2022] Open
Abstract
α-l-Fucosidase isoenzyme 1 from bacterium Paenibacillus thiaminolyticus is a member of the glycoside hydrolase family GH29 capable of cleaving l-fucose from nonreducing termini of oligosaccharides and glycoconjugates. Here we present the first crystal structure of this protein revealing a novel quaternary state within this family. The protein is in a unique hexameric assembly revealing the first observed case of active site complementation by a residue from an adjacent monomer in this family. Mutation of the complementing tryptophan residue caused changes in the catalytic properties including a shift of the pH optimum, a change of affinity to an artificial chromogenic substrate and a decreased reaction rate for a natural substrate. The wild-type enzyme was active on most of the tested naturally occurring oligosaccharides and capable of transglycosylation on a variety of acceptor molecules, including saccharides, alcohols or chromogenic substrates. Mutation of the complementing residue changed neither substrate specificity nor the preference for the type of transglycosylation acceptor molecule; however, the yields of the reactions were lower in both cases. Maltose molecules bound to the enzyme in the crystal structure identified surface carbohydrate-binding sites, possibly participating in binding of larger oligosaccharides.
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Affiliation(s)
- Terézia Kovalová
- Laboratory of Structure and Function of Biomolecules, Institute of Biotechnology of the Czech Academy of Sciences, v.v.i., Biocev, Vestec, Czech Republic.,Department of Biochemistry and Microbiology, University of Chemistry and Technology, Prague, Czech Republic
| | - Tomáš Koval
- Laboratory of Structure and Function of Biomolecules, Institute of Biotechnology of the Czech Academy of Sciences, v.v.i., Biocev, Vestec, Czech Republic
| | - Eva Benešová
- Department of Biochemistry and Microbiology, University of Chemistry and Technology, Prague, Czech Republic
| | - Patricie Vodicková
- Department of Biochemistry and Microbiology, University of Chemistry and Technology, Prague, Czech Republic
| | - Vojtech Spiwok
- Department of Biochemistry and Microbiology, University of Chemistry and Technology, Prague, Czech Republic
| | - Petra Lipovová
- Department of Biochemistry and Microbiology, University of Chemistry and Technology, Prague, Czech Republic
| | - Jan Dohnálek
- Laboratory of Structure and Function of Biomolecules, Institute of Biotechnology of the Czech Academy of Sciences, v.v.i., Biocev, Vestec, Czech Republic
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Geronimo I, Ntarima P, Piens K, Gudmundsson M, Hansson H, Sandgren M, Payne CM. Kinetic and molecular dynamics study of inhibition and transglycosylation in Hypocrea jecorina family 3 β-glucosidases. J Biol Chem 2019; 294:3169-3180. [PMID: 30602567 DOI: 10.1074/jbc.ra118.007027] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2018] [Indexed: 01/09/2023] Open
Abstract
β-Glucosidases enhance enzymatic biomass conversion by relieving cellobiose inhibition of endoglucanases and cellobiohydrolases. However, the susceptibility of these enzymes to inhibition and transglycosylation at high glucose or cellobiose concentrations severely limits their activity and, consequently, the overall efficiency of enzyme mixtures. We determined the impact of these two processes on the hydrolytic activity of the industrially relevant family 3 β-glucosidases from Hypocrea jecorina, HjCel3A and HjCel3B, and investigated the underlying molecular mechanisms through kinetic studies, binding free energy calculations, and molecular dynamics (MD) simulations. HjCel3B had a 7-fold higher specificity for cellobiose than HjCel3A but greater tendency for glucose inhibition. Energy decomposition analysis indicated that cellobiose has relatively weak electrostatic interactions with binding site residues, allowing it to be easily displaced by glucose and free to inhibit other hydrolytic enzymes. HjCel3A is, thus, preferable as an industrial β-glucosidase despite its lower activity caused by transglycosylation. This competing pathway to hydrolysis arises from binding of glucose or cellobiose at the product site after formation of the glycosyl-enzyme intermediate. MD simulations revealed that binding is facilitated by hydrophobic interactions with Trp-37, Phe-260, and Tyr-443. Targeting these aromatic residues for mutation to reduce substrate affinity at the product site would therefore potentially mitigate transglycosidic activity. Engineering improved variants of HjCel3A and other structurally similar β-glucosidases would have a significant economic effect on enzymatic biomass conversion in terms of yield and production cost as the process can be consequently conducted at higher substrate loadings.
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Affiliation(s)
- Inacrist Geronimo
- From the Department of Chemical and Materials Engineering, University of Kentucky, Lexington, Kentucky 40506-0046
| | - Patricia Ntarima
- the Department of Biochemistry and Microbiology, Ghent University, Ghent 9000, Belgium, and
| | - Kathleen Piens
- the Department of Biochemistry and Microbiology, Ghent University, Ghent 9000, Belgium, and
| | - Mikael Gudmundsson
- the Department of Molecular Sciences, Swedish University of Agricultural Sciences, Box 7015, 750 07 Uppsala, Sweden
| | - Henrik Hansson
- the Department of Molecular Sciences, Swedish University of Agricultural Sciences, Box 7015, 750 07 Uppsala, Sweden
| | - Mats Sandgren
- the Department of Molecular Sciences, Swedish University of Agricultural Sciences, Box 7015, 750 07 Uppsala, Sweden
| | - Christina M Payne
- From the Department of Chemical and Materials Engineering, University of Kentucky, Lexington, Kentucky 40506-0046, .,the Department of Molecular Sciences, Swedish University of Agricultural Sciences, Box 7015, 750 07 Uppsala, Sweden
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Zhu X, Soliman A, Islam MR, Adam LR, Daayf F. Verticillium dahliae's Isochorismatase Hydrolase Is a Virulence Factor That Contributes to Interference With Potato's Salicylate and Jasmonate Defense Signaling. FRONTIERS IN PLANT SCIENCE 2017; 8:399. [PMID: 28400778 PMCID: PMC5368275 DOI: 10.3389/fpls.2017.00399] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2016] [Accepted: 03/08/2017] [Indexed: 05/05/2023]
Abstract
This study aimed to dissect the function of the Isochorismatase Hydrolase (ICSH1) gene in Verticillium dahliae's pathogenesis on potato. VdICSH1 was up-regulated in V. dahliae after induction with extracts from potato tissues. Its expression increased more in response to root extracts than to leaf and stem extracts. However, such expression in response to root extracts was not significantly different in the highly and weakly aggressive isolates tested. During infection of detached potato leaves, VdICSH1 expression increased significantly in the highly aggressive isolate compared to the weakly aggressive one. We generated icsh1 mutants from a highly aggressive isolate of V. dahliae and compared their pathogenicity with that of the original wild type strain. The analysis showed that this gene is required for full virulence of V. dahliae on potatoes. When we previously found differential accumulation of ICSH1 protein in favor of the highly aggressive isolate, as opposed to the weakly aggressive one, we had hypothesized that ICSH would interfere with the host's defense SA-based signaling. Here, we measured the accumulation of both salicylic acid (SA) and jasmonic acid (JA) in potato plants inoculated with an icsh1 mutant in comparison with the wild type strain. The higher accumulation of bound SA in the leaves in response to the icsh1 mutant compared to the wild type confirms the hypothesis that ICSH1 interferes with SA. However, the different trends in SA and JA accumulation in potato in the roots and in the stems at the early infection stages compared to the leaves at later stages indicate that they are both associated to potato defenses against V. dahliae. The expression of members of the isochorismatase family in the icsh1 mutants compensate that of ICSH1 transcripts, but this compensation disappears in presence of the potato leaf extracts. This study indicates ICSH1's involvement in V. dahliae's pathogenicity and provides more insight into its alteration of the SA/JA defense signaling's networking.
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Affiliation(s)
- Xiaohan Zhu
- Department of Plant Science, University of Manitoba, WinnipegMB, Canada
| | - Atta Soliman
- Department of Plant Science, University of Manitoba, WinnipegMB, Canada
- Department of Genetics, Faculty of Agriculture, University of TantaTanta, Egypt
| | - Md. R. Islam
- Department of Plant Pathology, Bangladesh Agricultural UniversityMymensingh, Bangladesh
| | - Lorne R. Adam
- Department of Plant Science, University of Manitoba, WinnipegMB, Canada
| | - Fouad Daayf
- Department of Plant Science, University of Manitoba, WinnipegMB, Canada
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Wang D, Kim DH, Yun EJ, Park YC, Seo JH, Kim KH. The first bacterial β-1,6-endoglucanase from Saccharophagus degradans 2-40 T for the hydrolysis of pustulan and laminarin. Appl Microbiol Biotechnol 2017; 101:197-204. [PMID: 27521023 DOI: 10.1007/s00253-016-7753-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Revised: 07/21/2016] [Accepted: 07/27/2016] [Indexed: 10/21/2022]
Abstract
β-1,6-glucan is a polysaccharide found in brown macroalgae and fungal cell walls. In this study, a β-1,6-endoglucanase gene from Saccharophagus degradans 2-40T, gly30B, was cloned and overexpressed in Escherichia coli. Gly30B, which belongs to the glycoside hydrolase family 30 (GH30), was found to possess β-1,6-endoglucanase activity by hydrolyzing β-1,6-glycosidic linkages of pustulan (β-1,6-glucan derived from fungal cell walls) and laminarin (β-1,3-glucan with β-1,6-branchings, derived from brown macroalgae) to produce gentiobiose and glucose as the final products. The optimal pH and temperature for Gly30B activity were found to be pH 7.0 and 40 °C, respectively. The kinetic constants of Gly30B, V max, K M, and k cat were determined to be 153.8 U/mg protein, 24.2 g/L, and 135.6 s-1 for pustulan and 32.8 U/mg protein, 100.8 g/L, and 28.9 s-1 for laminarin, respectively. To our knowledge, Gly30B is the first β-1,6-endoglucanase characterized from bacteria. Gly30B can be used to hydrolyze β-1,6-glucans of brown algae or fungal cell walls for producing gentiobiose as a high-value sugar and glucose as a fermentable sugar.
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Affiliation(s)
- Damao Wang
- Department of Biotechnology, Graduate School, Korea University, Seoul, 02841, South Korea
| | - Do Hyoung Kim
- Department of Biotechnology, Graduate School, Korea University, Seoul, 02841, South Korea
| | - Eun Ju Yun
- Department of Biotechnology, Graduate School, Korea University, Seoul, 02841, South Korea
| | - Yong-Cheol Park
- Department of Bio and Fermentation Convergence Technology, Kookmin University, Seoul, 02707, South Korea
| | - Jin-Ho Seo
- Department of Agricultural Biotechnology, Seoul National University, Seoul, 08826, South Korea
| | - Kyoung Heon Kim
- Department of Biotechnology, Graduate School, Korea University, Seoul, 02841, South Korea.
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Two New Native β-Glucosidases from Clavispora NRRL Y-50464 Confer Its Dual Function as Cellobiose Fermenting Ethanologenic Yeast. PLoS One 2016; 11:e0151293. [PMID: 27011316 PMCID: PMC4806929 DOI: 10.1371/journal.pone.0151293] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 02/25/2016] [Indexed: 11/19/2022] Open
Abstract
Yeast strain Clavispora NRRL Y-50464 is able to produce cellulosic ethanol from lignocellulosic materials without addition of external β-glucosidase by simultaneous saccharification and fermentation. A β-glucosidase BGL1 protein from this strain was recently reported supporting its cellobiose utilization capability. Here, we report two additional new β-glucosidase genes encoding enzymes designated as BGL2 and BGL3 from strain NRRL Y-50464. Quantitative gene expression was analyzed and the gene function of BGL2 and BGL3 was confirmed by heterologous expression using cellobiose as a sole carbon source. Each gene was cloned and partially purified protein obtained separately for direct enzyme assay using varied substrates. Both proteins showed the highest specific activity at pH 5 and relatively strong affinity with a Km of 0.08 and 0.18 mM for BGL2 and BGL3, respectively. The optimum temperature was found to be 50°C for BGL2 and 55°C for BGL3. Both proteins were able to hydrolyze 1,4 oligosaccharides evaluated in this study. They also showed a strong resistance to glucose product inhibition with a Ki of 61.97 and 38.33 mM for BGL2 and BGL3, respectively. While BGL3 was sensitive showing a significantly reduced activity to 4% ethanol, BGL2 demonstrated tolerance to ethanol. Its activity was enhanced in the presence of ethanol but reduced at concentrations greater than 16%. The presence of the fermentation inhibitors furfural and HMF did not affect the enzyme activity. Our results suggest that a β-glucosidase gene family exists in Clavispora NRRL Y-50464 with at least three members in this group that validate its cellobiose hydrolysis functions for lower-cost cellulosic ethanol production. Results of this study confirmed the cellobiose hydrolysis function of strain NRRL Y-50464, and further supported this dual functional yeast as a candidate for lower-cost cellulosic ethanol production and next-generation biocatalyst development in potential industrial applications.
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Larue K, Melgar M, Martin VJJ. Directed evolution of a fungal β-glucosidase in Saccharomyces cerevisiae. BIOTECHNOLOGY FOR BIOFUELS 2016; 9:52. [PMID: 26949413 PMCID: PMC4778352 DOI: 10.1186/s13068-016-0470-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Accepted: 02/22/2016] [Indexed: 05/13/2023]
Abstract
BACKGROUND β-glucosidases (BGLs) catalyze the hydrolysis of soluble cellodextrins to glucose and are a critical component of cellulase systems. In order to engineer Saccharomyces cerevisiae for the production of ethanol from cellulosic biomass, a BGL tailored to industrial bioconversions is needed. RESULTS We applied a directed evolution strategy to a glycosyl hydrolase family 3 (GH3) BGL from Aspergillus niger (BGL1) by expressing a library of mutated bgl1 genes in S. cerevisiae and used a two-step functional screen to identify improved enzymes. Twelve BGL variants that supported growth of S. cerevisiae on cellobiose and showed increased activity on the synthetic substrate p-nitrophenyl-β-D-glucopyranoside were identified and characterized. By performing kinetic experiments, we found that a Tyr → Cys substitution at position 305 of BGL1 dramatically reduced transglycosidation activity that causes inhibition of the hydrolytic reaction at high substrate concentrations. Targeted mutagenesis demonstrated that the position 305 residue is critical in GH3 BGLs and likely determines the extent to which transglycosidation reactions occur. We also found that a substitution at Gln(140) reduced the inhibitory effect of glucose and could be combined with the Y305C substitution to produce a BGL with decreased sensitivity to both the product and substrate. Using the crystal structure of a GH3 BGL from A. aculeatus, we mapped a group of beneficial mutations to the β/α domain of the molecule and postulate that this region modulates activity through subunit interactions. Six BGL variants were identified with substitutions in the MFα pre-sequence that was used to mediate secretion of the protein. Substitutions at Pro(21) or Val(22) of the MFα pre-sequence could produce up to a twofold increase in supernatant hydrolase activity and provides evidence that expression and/or secretion was an additional factor limiting hydrolytic activity. CONCLUSIONS Using directed evolution on BGL1, we identified a key residue that controls hydrolytic and transglycosidation reactions in GH3 BGLs. We also found that several beneficial mutations could be combined and increased the hydrolytic activity for both synthetic and natural substrates.
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Affiliation(s)
- Kane Larue
- Department of Biology, Centre for Structural and Functional Genomics, Concordia University, 7141 Sherbrooke West, Montreal, QC H4B 1R6 Canada
| | - Mindy Melgar
- Department of Biology, Centre for Structural and Functional Genomics, Concordia University, 7141 Sherbrooke West, Montreal, QC H4B 1R6 Canada
| | - Vincent J. J. Martin
- Department of Biology, Centre for Structural and Functional Genomics, Concordia University, 7141 Sherbrooke West, Montreal, QC H4B 1R6 Canada
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Baba Y, Sumitani JI, Tani S, Kawaguchi T. Characterization of Aspergillus aculeatus β-glucosidase 1 accelerating cellulose hydrolysis with Trichoderma cellulase system. AMB Express 2015; 5:3. [PMID: 25642400 PMCID: PMC4305095 DOI: 10.1186/s13568-014-0090-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2014] [Accepted: 12/23/2014] [Indexed: 11/10/2022] Open
Abstract
Aspergillus aculeatus β-glucosidase 1 (AaBGL1), which promotes cellulose hydrolysis by Trichoderma cellulase system, was characterized and compared some properties to a commercially supplied orthologue in A. niger (AnBGL) to elucidate advantages of recombinant AaBGL1 (rAaBGL1) for synergistic effect on Trichoderma enzymes. Steady-state kinetic studies revealed that rAaBGL1 showed high catalytic efficiency towards β-linked glucooligosaccharides. Up to a degree of polymerization (DP) 3, rAaBGL1 prefered to hydrolyze β-1,3 linked glucooligosaccharides, but longer than DP 3, preferred β-1,4 glucooligosaccharides (up to DP 5). This result suggested that there were different formation for subsites in the catalytic cleft of AaBGL1 between β-1,3 and β-1,4 glucooligosaccharides, therefore rAaBGL1 preferred short chain of laminarioligosaccharides and long chain of cellooligosaccharides on hydrolysis. rAaBGL1 was more insensitive to glucose inhibition and more efficient to hydrolyze the one of major transglycosylation product, gentiobiose than AnBGL, resulting that rAaBGL1 completely hydrolyzed 5% cellobiose to glucose faster than AnBGL. These data indicate that AaBGL1 is valuable for the use of cellulosic biomass conversion.
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Cao LC, Wang ZJ, Ren GH, Kong W, Li L, Xie W, Liu YH. Engineering a novel glucose-tolerant β-glucosidase as supplementation to enhance the hydrolysis of sugarcane bagasse at high glucose concentration. BIOTECHNOLOGY FOR BIOFUELS 2015; 8:202. [PMID: 26628916 PMCID: PMC4666061 DOI: 10.1186/s13068-015-0383-z] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2015] [Accepted: 11/16/2015] [Indexed: 05/02/2023]
Abstract
BACKGROUND Most β-glucosidases reported are sensitive to the end product (glucose), making it the rate limiting component of cellulase for efficient degradation of cellulose through enzymatic route. Thus, there are ongoing interests in searching for glucose-tolerant β-glucosidases, which are still active at high glucose concentration. Although many β-glucosidases with different glucose-tolerance levels have been isolated and characterized in the past decades, the effects of glucose-tolerance on the hydrolysis of cellulose are not thoroughly studied. RESULTS In the present study, a novel β-glucosidase (Bgl6) with the half maximal inhibitory concentration (IC 50) of 3.5 M glucose was isolated from a metagenomic library and characterized. However, its poor thermostability at 50 °C hindered the employment in cellulose hydrolysis. To improve its thermostability, random mutagenesis was performed. A thermostable mutant, M3, with three amino acid substitutions was obtained. The half-life of M3 at 50 °C is 48 h, while that of Bgl6 is 1 h. The K cat/K m value of M3 is 3-fold higher than that of Bgl6. The mutations maintained its high glucose-tolerance with IC 50 of 3.0 M for M3. In a 10-h hydrolysis of cellobiose, M3 completely converted cellobiose to glucose, while Bgl6 reached a conversion of 80 %. Then their synergistic effects with the commercial cellulase (Celluclast 1.5 L) on hydrolyzing pretreated sugarcane bagasse (SCB) were investigated. The supplementation of Bgl6 or mutant M3 to Celluclast 1.5 L significantly improved the SCB conversion from 64 % (Celluclast 1.5 L alone) to 79 % (Bgl6) and 94 % (M3), respectively. To further evaluate the application potential of M3 in high-solids cellulose hydrolysis, such reactions were performed at initial glucose concentration of 20-500 mM. Results showed that the supplementation of mutant M3 enhanced the glucose production from SCB under all the conditions tested, improving the SCB conversion by 14-35 %. CONCLUSIONS These results not only clearly revealed the significant role of glucose-tolerance in cellulose hydrolysis, but also showed that mutant M3 may be a potent candidate for high-solids cellulose refining.
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Affiliation(s)
- Li-chuang Cao
- />School of Life Sciences, Sun Yat-sen University, Guangzhou, 510275 People’s Republic of China
- />South China Sea Bio-Resource Exploitation and Utilization Collaborative Innovation Center, Sun Yat-sen University, Guangzhou, 510275 People’s Republic of China
| | - Zhi-jun Wang
- />School of Life Sciences, Sun Yat-sen University, Guangzhou, 510275 People’s Republic of China
- />South China Sea Bio-Resource Exploitation and Utilization Collaborative Innovation Center, Sun Yat-sen University, Guangzhou, 510275 People’s Republic of China
| | - Guang-hui Ren
- />School of Life Sciences, Sun Yat-sen University, Guangzhou, 510275 People’s Republic of China
- />South China Sea Bio-Resource Exploitation and Utilization Collaborative Innovation Center, Sun Yat-sen University, Guangzhou, 510275 People’s Republic of China
| | - Wei Kong
- />School of Life Sciences, Sun Yat-sen University, Guangzhou, 510275 People’s Republic of China
- />South China Sea Bio-Resource Exploitation and Utilization Collaborative Innovation Center, Sun Yat-sen University, Guangzhou, 510275 People’s Republic of China
| | - Liang Li
- />School of Life Sciences, Sun Yat-sen University, Guangzhou, 510275 People’s Republic of China
- />South China Sea Bio-Resource Exploitation and Utilization Collaborative Innovation Center, Sun Yat-sen University, Guangzhou, 510275 People’s Republic of China
| | - Wei Xie
- />State Key Laboratory for Biocontrol, School of Life Sciences, Sun Yat-sen University, Guangzhou, 510275 People’s Republic of China
| | - Yu-huan Liu
- />School of Life Sciences, Sun Yat-sen University, Guangzhou, 510275 People’s Republic of China
- />South China Sea Bio-Resource Exploitation and Utilization Collaborative Innovation Center, Sun Yat-sen University, Guangzhou, 510275 People’s Republic of China
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Gao J, Wakarchuk W. Characterization of five β-glycoside hydrolases from Cellulomonas fimi ATCC 484. J Bacteriol 2014; 196:4103-10. [PMID: 25225266 PMCID: PMC4248878 DOI: 10.1128/jb.02194-14] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2014] [Accepted: 09/04/2014] [Indexed: 11/20/2022] Open
Abstract
The Gram-positive bacterium Cellulomonas fimi produces a large array of carbohydrate-active enzymes. Analysis of the collection of carbohydrate-active enzymes from the recent genome sequence of C. fimi ATCC 484 shows a large number of uncharacterized genes for glycoside hydrolase (GH) enzymes potentially involved in biomass utilization. To investigate the enzymatic activity of potential β-glucosidases in C. fimi, genes encoding several GH3 enzymes and one GH1 enzyme were cloned and recombinant proteins were expressed in Escherichia coli. Biochemical analysis of these proteins revealed that the enzymes exhibited different substrate specificities for para-nitrophenol-linked substrates (pNP), disaccharides, and oligosaccharides. Celf_2726 encoded a bifunctional enzyme with β-d-xylopyranosidase and α-l-arabinofuranosidase activities, based on pNP-linked substrates (CfXyl3A). Celf_0140 encoded a β-d-glucosidase with activity on β-1,3- and β-1,6-linked glucosyl disaccharides as well as pNP-β-Glc (CfBgl3A). Celf_0468 encoded a β-d-glucosidase with hydrolysis of pNP-β-Glc and hydrolysis/transglycosylation activities only on β-1,6-linked glucosyl disaccharide (CfBgl3B). Celf_3372 encoded a GH3 family member with broad aryl-β-d-glycosidase substrate specificity. Celf_2783 encoded the GH1 family member (CfBgl1), which was found to hydrolyze pNP-β-Glc/Fuc/Gal, as well as cellotetraose and cellopentaose. CfBgl1 also had good activity on β-1,2- and β-1,3-linked disaccharides but had only very weak activity on β-1,4/6-linked glucose.
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Affiliation(s)
- Juan Gao
- School of Life Sciences, Northeast Normal University, Changchun, Jilin Province, People's Republic of China
| | - Warren Wakarchuk
- Department of Chemistry and Biology, Ryerson University, Toronto, Ontario, Canada
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Thongpoo P, Srisomsap C, Chokchaichamnankit D, Kitpreechavanich V, Svasti J, Kongsaeree PT. Purification and characterization of three β-glycosidases exhibiting high glucose tolerance from Aspergillus niger ASKU28. Biosci Biotechnol Biochem 2014; 78:1167-76. [PMID: 25229852 DOI: 10.1080/09168451.2014.915727] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Production and utilization of cellulosic ethanol has been limited, partly due to the difficulty in degradation of cellulosic feedstock. β-Glucosidases convert cellobiose to glucose in the final step of cellulose degradation, but they are inhibited by high concentrations of glucose. Thus, in this study, we have screened, isolated, and characterized three β-glycosidases exhibiting highly glucose-tolerant property from Aspergillus niger ASKU28, namely β-xylosidase (P1.1), β-glucosidase (P1.2), and glucan 1,3-β-glucosidase (P2). Results from kinetic analysis, inhibition study, and hydrolysis of oligosaccharide substrates supported the identification of these enzymes by both LC/MS/MS analysis and nucleotide sequences. Moreover, the highly efficient P1.2 performed better than the commercial β-glucosidase preparation in cellulose saccharification, suggesting its potential applications in the cellulosic ethanol industry. These results shed light on the nature of highly glucose-tolerant β-glucosidase activities in A. niger, whose kinetic properties and identities have not been completely determined in any prior investigations.
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Affiliation(s)
- Preeyanuch Thongpoo
- a Interdisciplinary Graduate Program in Genetic Engineering, Faculty of Graduate School , Kasetsart University , Bangkok , Thailand
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Characterization of a Glycoside Hydrolase Family 31 α-Glucosidase Involved in Starch Utilization inPodospora anserina. Biosci Biotechnol Biochem 2014; 77:2117-24. [DOI: 10.1271/bbb.130545] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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Reaction kinetics of substrate transglycosylation catalyzed by TreX of Sulfolobus solfataricus and effects on glycogen breakdown. J Bacteriol 2014; 196:1941-9. [PMID: 24610710 DOI: 10.1128/jb.01442-13] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We studied the activity of a debranching enzyme (TreX) from Sulfolobus solfataricus on glycogen-mimic substrates, branched maltotetraosyl-β-cyclodextrin (Glc₄-β-CD), and natural glycogen to better understand substrate transglycosylation and the effect thereof on glycogen debranching in microorganisms. The validation test of Glc₄-β-CD as a glycogen mimic substrate showed that it followed the breakdown process of the well-known yeast and rat liver extract. TreX catalyzed both hydrolysis of α-1,6-glycosidic linkages and transglycosylation at relatively high (>0.5 mM) substrate concentrations. TreX transferred maltotetraosyl moieties from the donor substrate to acceptor molecules, resulting in the formation of two positional isomers of dimaltotetraosyl-α-1,6-β-cyclodextrin [(Glc₄)₂-β-CD]; these were 6(1),6(3)- and 6(1),6(4)-dimaltotetraosyl-α-1,6-β-CD. Use of a modified Michaelis-Menten equation to study substrate transglycosylation revealed that the kcat and Km values for transglycosylation were 1.78 × 10(3) s(-1) and 3.30 mM, respectively, whereas the values for hydrolysis were 2.57 × 10(3) s(-1) and 0.206 mM, respectively. Also, enzyme catalytic efficiency (the kcat/Km ratio) increased as the degree of polymerization of branch chains rose. In the model reaction system of Escherichia coli, glucose-1-phosphate production from glycogen by the glycogen phosphorylase was elevated ∼1.45-fold in the presence of TreX compared to that produced in the absence of TreX. The results suggest that outward shifting of glycogen branch chains via transglycosylation increases the number of exposed chains susceptible to phosphorylase action. We developed a model of the glycogen breakdown process featuring both hydrolysis and transglycosylation catalyzed by the debranching enzyme.
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Pavlović M, Dimitrijević A, Trbojević J, Milosavić N, Gavrović-Jankulović M, Bezbradica D, Veličković D. A study of transglucosylation kinetic in an enzymatic synthesis of benzyl alcohol glucoside by α-glucosidase from S. cerevisiae. RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY A 2013. [DOI: 10.1134/s0036024413130207] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Teugjas H, Väljamäe P. Selecting β-glucosidases to support cellulases in cellulose saccharification. BIOTECHNOLOGY FOR BIOFUELS 2013; 6:105. [PMID: 23883540 PMCID: PMC3726394 DOI: 10.1186/1754-6834-6-105] [Citation(s) in RCA: 73] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Accepted: 07/11/2013] [Indexed: 05/02/2023]
Abstract
BACKGROUND Enzyme end-product inhibition is a major challenge in the hydrolysis of lignocellulose at a high dry matter consistency. β-glucosidases (BGs) hydrolyze cellobiose into two molecules of glucose, thereby relieving the product inhibition of cellobiohydrolases (CBHs). However, BG inhibition by glucose will eventually lead to the accumulation of cellobiose and the inhibition of CBHs. Therefore, the kinetic properties of candidate BGs must meet the requirements determined by both the kinetic properties of CBHs and the set-up of the hydrolysis process. RESULTS The kinetics of cellobiose hydrolysis and glucose inhibition of thermostable BGs from Acremonium thermophilum (AtBG3) and Thermoascus aurantiacus (TaBG3) was studied and compared to Aspergillus sp. BG purified from Novozyme®188 (N188BG). The most efficient cellobiose hydrolysis was achieved with TaBG3, followed by AtBG3 and N188BG, whereas the enzyme most sensitive to glucose inhibition was AtBG3, followed by TaBG3 and N188BG. The use of higher temperatures had an advantage in both increasing the catalytic efficiency and relieving the product inhibition of the enzymes. Our data, together with data from a literature survey, revealed a trade-off between the strength of glucose inhibition and the affinity for cellobiose; therefore, glucose-tolerant BGs tend to have low specificity constants for cellobiose hydrolysis. However, although a high specificity constant is always an advantage, in separate hydrolysis and fermentation, the priority may be given to a higher tolerance to glucose inhibition. CONCLUSIONS The specificity constant for cellobiose hydrolysis and the inhibition constant for glucose are the most important kinetic parameters in selecting BGs to support cellulases in cellulose hydrolysis.
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Affiliation(s)
- Hele Teugjas
- Institute of Molecular and Cell Biology, University of Tartu, Riia 23b – 202, 51010, Tartu, Estonia
| | - Priit Väljamäe
- Institute of Molecular and Cell Biology, University of Tartu, Riia 23b – 202, 51010, Tartu, Estonia
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25
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Dimitrijević A, Veličković D, Milosavić N, Bezbradica D. Specificity of maltase to maltose in three different directions of reaction: hydrolytic, vanillyl alcohol glucoside and vanillyl alcohol isomaltoside synthesis. Biotechnol Prog 2012; 28:1450-6. [PMID: 22927369 DOI: 10.1002/btpr.1628] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2012] [Revised: 08/21/2012] [Indexed: 11/09/2022]
Abstract
Vanillyl alcohol glucoside is very attractive molecule due to its very powerful physiological activity. In this article, a detailed kinetic study of transglucosylation of vanillyl alcohol was performed. It was demonstrated that this reaction is very efficient (selectivity factor is 149) and occurred by a ping-pong mechanism with inhibition by glucose acceptor. At low concentration of vanillyl alcohol one additional transglucosylation product was detected. Its structure was determined to be α-isomaltoside of vanillyl alcohol, indicating that vanillyl alcohol glucoside is a product of the first transglucosylation reaction and a substrate for second, so the whole reaction mechanism was proposed. It was demonstrated that the rate of isomaltoside synthesis is two orders of magnitude smaller than glucoside synthesis, and that maltase has interestingly high K(m) value to maltose when vanillyl alcohol glucoside is second transglucosylation substrate.
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Affiliation(s)
- Aleksandra Dimitrijević
- Faculty of Chemistry, Department of Biochemistry, University of Belgrade, Studentski trg 12, Belgrade, Serbia
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26
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Radva D, Knutsen SH, Kosáry J, Ballance S. Application of high-performance anion-exchange chromatography with pulsed amperometric detection to compare the kinetic properties of β-glucosidase on oligosaccharides from lichenase digested barley β-glucan. Carbohydr Res 2012; 358:56-60. [DOI: 10.1016/j.carres.2012.06.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2012] [Revised: 06/04/2012] [Accepted: 06/13/2012] [Indexed: 11/26/2022]
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27
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Transcriptional response of the cellobiose dehydrogenase gene to cello- and xylooligosaccharides in the basidiomycete Phanerochaete chrysosporium. Appl Environ Microbiol 2012; 78:3770-3. [PMID: 22407682 DOI: 10.1128/aem.00150-12] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cellobiose dehydrogenase (CDH) gene transcripts were quantified by reverse transcription-PCR (RT-PCR) in cultures of Phanerochaete chrysosporium supplemented with various cello- and xylooligosaccharides in order to elucidate the mechanism of enhanced CDH production in xylan/cellulose culture. Cellotriose and cellotetraose induced cdh expression, while xylobiose and xylotriose induced expression of cellobiohydrolase genes, especially cel7C.
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Bohlin C, Praestgaard E, Baumann MJ, Borch K, Praestgaard J, Monrad RN, Westh P. A comparative study of hydrolysis and transglycosylation activities of fungal β-glucosidases. Appl Microbiol Biotechnol 2012; 97:159-69. [PMID: 22311644 DOI: 10.1007/s00253-012-3875-9] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2011] [Revised: 12/22/2011] [Accepted: 12/28/2011] [Indexed: 11/30/2022]
Abstract
β-glucosidases (BGs) from Aspergillus fumigatus, Aspergillus niger, Aspergillus oryzae, Magnaporthe grisea, Neurospora crassa, and Penicillium brasilianum were purified to homogeneity, and investigated for their (simultaneous) hydrolytic and transglycosylation activity in samples with high concentrations of either cellobiose or glucose. The rate of the hydrolytic process (which converts one cellobiose to two glucose molecules) shows a maximum around 10-15 mM cellobiose and decreases with further increase in the concentration of substrate. At the highest investigated concentration (100 mM cellobiose), the hydrolytic activity for the different enzymes ranged from 10% to 55% of the maximum value. This decline in hydrolysis was essentially compensated by increased transglycosylation (which converts two cellobiose to one glucose and one trisaccharide). Hence, it was concluded that the hydrolytic slowdown at high substrate concentrations solely relies on an increased flow through the transglycosylation pathway and not an inhibition that delays the catalytic cycle. Transglycosylation was also detected at high product (glucose) concentrations, but in this case, it was not a major cause for the slowdown in hydrolysis. The experimental data was modeled to obtain kinetic parameters for both hydrolysis and transglycosylation. These parameters were subsequently used in calculations that quantified the negative effects on BG activity of respectively transglycosylation and product inhibition. The kinetic parameters and the mathematical method presented here allow estimation of these effects, and we suggest that this may be useful for the evaluation of BGs for industrial use.
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Affiliation(s)
- Christina Bohlin
- Roskilde University, NSM, Biomaterials, Universitetsvej 1, DK-4000, Roskilde, Denmark
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29
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Veličković DV, Dimitrijević AS, Bihelović FJ, Jankov RM, Milosavić N. Study of the kinetic parameters for synthesis and hydrolysis of pharmacologically active salicin isomer catalyzed by baker’s yeast maltase. RUSSIAN JOURNAL OF PHYSICAL CHEMISTRY A 2011. [DOI: 10.1134/s0036024411130346] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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30
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Nakajima M, Yamashita T, Takahashi M, Nakano Y, Takeda T. Identification, cloning, and characterization of β-glucosidase from Ustilago esculenta. Appl Microbiol Biotechnol 2011; 93:1989-98. [PMID: 21850431 DOI: 10.1007/s00253-011-3538-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Revised: 07/23/2011] [Accepted: 08/05/2011] [Indexed: 11/25/2022]
Abstract
Hydrolytic enzymes responsible for laminarin degradation were found to be secreted during growth of Ustilago esculenta on laminarin. An enzyme involved in laminarin degradation was purified by assaying release of glucose from laminaribiose. Ion-exchange chromatography of the culture filtrate followed by size-exclusion chromatography yielded a 110-kDa protein associated with laminaribiose hydrolysis. LC/MS/MS analysis of the 110-kDa protein identified three peptide sequences that shared significant similarity with a putative glucoside hydrolase family (GH) 3 β-glucosidase in Ustilago maydis. Based on the DNA sequence of the U. maydis GH3 β-glucosidase, a gene encoding a putative GH3 β-glucosidase in U. esculenta (Uebgl3A) was cloned by PCR. Based on the deduced amino acid sequence, the protein encoded by Uebgl3A has a molecular mass of 91 kDa and shares 90% identity with U. maydis GH3 β-glucosidase. Recombinant UeBgl3A expressed in Aspergillus oryzae released glucose from β-1,3-, β-1,4-, and β-1,6-linked oligosaccharides, and from 1,3-1,4-β-glucan and laminarin polysaccharides, indicating that UeBgl3A is a β-glucosidase. Kinetic analysis showed that UeBgl3A preferentially hydrolyzed laminaritriose and laminaritetraose. These results suggest that UeBgl3A is a key enzyme that produces glucose from laminarioligosaccharides during growth of U. esculenta on laminarin.
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Affiliation(s)
- Masahiro Nakajima
- Iwate Biotechnology Research Center, 22-174-4, Kitakami, Iwate, 024-0003, Japan
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31
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Calcium ion-dependent increase in thermostability of dextran glucosidase from Streptococcus mutans. Biosci Biotechnol Biochem 2011; 75:1557-63. [PMID: 21821929 DOI: 10.1271/bbb.110256] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Dextran glucosidase from Streptococcus mutans (SmDG), which belongs to glycoside hydrolase family 13 (GH13), hydrolyzes the non-reducing terminal glucosidic linkage of isomaltooligosaccharides and dextran. Thermal deactivation of SmDG did not follow the single exponential decay but rather the two-step irreversible deactivation model, which involves an active intermediate having 39% specific activity. The presence of a low concentration of CaCl2 increased the thermostability of SmDG, mainly due to a marked reduction in the rate constant of deactivation of the intermediate. The addition of MgCl2 also enhanced thermostability, while KCl and NaCl were not effective. Therefore, divalent cations, particularly Ca2+, were considered to stabilize SmDG. On the other hand, CaCl2 had no significant effect on catalytic reaction. The enhanced stability by Ca2+ was probably related to calcium binding in the β→α loop 1 of the (β/α)(8) barrel of SmDG. Because similar structures and sequences are widespread in GH13, these GH13 enzymes might have been stabilized by calcium ions.
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Bohlin C, Olsen SN, Morant MD, Patkar S, Borch K, Westh P. A comparative study of activity and apparent inhibition of fungal β-glucosidases. Biotechnol Bioeng 2011; 107:943-52. [PMID: 20677177 DOI: 10.1002/bit.22885] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
β-Glucosidases (BGs) from Aspergillus fumigates, Aspergillus niger, Aspergillus oryzae, Chaetomium globosum, Emericella nidulans, Magnaporthe grisea, Neurospora crassa, and Penicillium brasilianum were purified to homogeneity, and analyzed by isothermal titration calorimetry with respect to their hydrolytic activity and its sensitivity to glucose (product) using cellobiose as substrate. Global non-linear regression of several reactions, with or without added glucose, to a product inhibition equation enabled the concurrent derivation of the kinetic parameters k(cat), K(m), and the apparent product inhibition constant (app)K(i) for each of the enzymes. A more simple fit is not advisable to use as the determined (app)K(i) are in the same range as their K(m) for some of the tested BGs and produced glucose would in these cases interfere. The highest value for k(cat) was determined for A. fumigatus (768 s(-1)) and the lowest was a factor 9 less. K(m) varied by a factor of 3 with the lowest value determined for C. globosum (0.95 mM). The measured (app)K(i) varied a factor of 15; the hydrolytic activity of N. crassa being the most resistant to glucose with an apparent product inhibition constant of 10.1 mM. Determination of (app)K(i) using cellobiose as substrate is important as it reflects to what extent the different BGs are hydrolytically active under industrial conditions where natural substrates are hydrolyzed and the final glucose concentrations are high.
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Zhang H, Moon YH, Watson BJ, Suvorov M, Santos E, Sinnott CA, Hutcheson SW. Hydrolytic and phosphorolytic metabolism of cellobiose by the marine aerobic bacterium Saccharophagus degradans 2-40T. J Ind Microbiol Biotechnol 2011; 38:1117-25. [PMID: 21327449 DOI: 10.1007/s10295-011-0945-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2010] [Accepted: 01/21/2011] [Indexed: 11/27/2022]
Abstract
Saccharophagus degradans 2-40 is a marine gamma proteobacterium that can produce polyhydroxyalkanoates from lignocellulosic biomass using a complex cellulolytic system. This bacterium has been annotated to express three surface-associated β-glucosidases (Bgl3C, Ced3A, and Ced3B), two cytoplasmic β-glucosidases (Bgl1A and Bgl1B), and unusual for an aerobic bacterium, two cytoplasmic cellobiose/cellodextrin phosphorylases (Cep94A and Cep94B). Expression of the genes for each of the above enzymes was induced when cells were transferred into a medium containing Avicel as the major carbon source except for Bgl1B. Both hydrolytic and phosphorolytic degradation of cellobiose by crude cell lysates obtained from cellulose-grown cells were demonstrated and all of these activities were cell-associated. With the exception of Cep94B, each purified enzyme exhibited their annotated activity upon cloning and expression in E. coli. The five β-glucosidases hydrolyzed a variety of glucose derivatives containing β-1, (2, 4, or 6) linkages but did not act on any α-linked glucose derivatives. All but one β-glucosidases exhibited transglycosylation activity consistent with the formation of an enzyme-substrate intermediate. The biochemistry and expression of these cellobiases indicate that external hydrolysis by surface-associated β-glucosidases coupled with internal hydrolysis and phosphorolysis are all involved in the metabolism of cellobiose by this bacterium.
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Affiliation(s)
- Haitao Zhang
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, MD 20742, USA
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Dingee JW, Anton AB. The kinetics of p-nitrophenyl-β-D-cellobioside hydrolysis and transglycosylation by Thermobifida fusca Cel5Acd. Carbohydr Res 2010; 345:2507-15. [PMID: 20951981 DOI: 10.1016/j.carres.2010.09.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2009] [Revised: 09/07/2010] [Accepted: 09/09/2010] [Indexed: 10/19/2022]
Abstract
The hydrolysis of p-nitrophenyl-β-1,4-cellobioside (pNP-G2) by the catalytic domain of the retaining-family 5-2 endocellulase Cel5A from Thermobifida fusca (Cel5Acd) was studied. The dominant reaction pathway involves hydrolysis of the aglyconic bond, producing cellobiose (G2) and a 'reporter' species p-nitrophenol (pNP), which was monitored spectrophotometrically to track the reaction. We also detected the production of cellotriose (G3) and p-nitrophenyl-glucoside (pNP-G1), confirming the presence of a competing transglycosylation pathway. We use a mechanistic model of hydrolysis and transglycosylation to derive an expression for the rate of pNP-formation as a function of enzyme concentration, substrate concentration, and several lumped kinetics parameters. The derivation assumes that the quasi-steady-state assumption (QSSA) applies for three intermediate species in the mechanism; we determine conditions under which this assumption is rigorously justified. We integrate the rate expression and compare its integral form to pNP-versus-time data collected for a range of enzyme and substrate concentrations. The integral comparison gives a stringent test of the mechanistic model, and it serves to quantify the lumped kinetics parameters with good statistical precision, particularly a previously unidentified parameter that determines the selectivity of hydrolysis versus transglycosylation. The integrated rate expression accounts well for pNP-versus-time data under all circumstances we have investigated.
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Affiliation(s)
- John W Dingee
- School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY 14850, United States
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35
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Luang S, Hrmova M, Ketudat Cairns JR. High-level expression of barley beta-D-glucan exohydrolase HvExoI from a codon-optimized cDNA in Pichia pastoris. Protein Expr Purif 2010; 73:90-8. [PMID: 20406687 DOI: 10.1016/j.pep.2010.04.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2010] [Revised: 04/12/2010] [Accepted: 04/15/2010] [Indexed: 10/19/2022]
Abstract
The native beta-d-glucan exohydrolase isoenzyme ExoI from barley seedlings, designated HvExoI, was the first GH3 glycoside hydrolase, for which a crystal structure was determined. A precise understanding of relationships between structure and function in this enzyme has been gained by structural and enzymatic studies. To allow testing of hypotheses gained from these studies, an efficient system for expression of HvExoI in Pichia pastoris was developed using a codon-optimized cDNA. Protein expression at a temperature of 20 degrees C yielded a recombinant enzyme, designated rHvExoI, which had molecular masses of 70-110 kDa due to heavy glycosylation at Asn221, Asn498 and Asn600, the three sites of N-glycosylation in native HvExoI. Most of the N-linked carbohydrate could be removed from rHvExoI, resulting in N-deglycosylated rHvExoI with a substantially decreased molecular mass of 67 kDa. rHvExoI was able to hydrolyse barley (1,3;1,4)-beta-D-glucan, laminarin and lichenans. The catalytic efficiency value k(cat)/K(M) of rHvExoI with barley (1,3;1,4)-beta-D-glucan was similar to that reported for native HvExoI. Further, laminaribiose, cellobiose and gentiobiose were formed through transglycosylation reactions with 4-nitrophenyl beta-D-glucoside and barley (1,3;1,4)-beta-D-glucan. Overall, the biochemical properties of rHvExoI were similar to those reported for native HvExoI, although differences were seen in thermostabilities and hydrolytic rates of certain beta-linked glucosides.
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Affiliation(s)
- Sukanya Luang
- School of Biochemistry, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand
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Functional diversity of four glycoside hydrolase family 3 enzymes from the rumen bacterium Prevotella bryantii B14. J Bacteriol 2010; 192:2335-45. [PMID: 20190048 DOI: 10.1128/jb.01654-09] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Prevotella bryantii B(1)4 is a member of the phylum Bacteroidetes and contributes to the degradation of hemicellulose in the rumen. The genome of P. bryantii harbors four genes predicted to encode glycoside hydrolase (GH) family 3 (GH3) enzymes. To evaluate whether these genes encode enzymes with redundant biological functions, each gene was cloned and expressed in Escherichia coli. Biochemical analysis of the recombinant proteins revealed that the enzymes exhibit different substrate specificities. One gene encoded a cellodextrinase (CdxA), and three genes encoded beta-xylosidase enzymes (Xyl3A, Xyl3B, and Xyl3C) with different specificities for either para-nitrophenyl (pNP)-linked substrates or substituted xylooligosaccharides. To identify the amino acid residues that contribute to catalysis and substrate specificity within this family of enzymes, the roles of conserved residues (R177, K214, H215, M251, and D286) in Xyl3B were probed by site-directed mutagenesis. Each mutation led to a severely decreased catalytic efficiency without a change in the overall structure of the mutant enzymes. Through amino acid sequence alignments, an amino acid residue (E115) that, when mutated to aspartic acid, resulted in a 14-fold decrease in the k(cat)/K(m) for pNP-beta-d-xylopyranoside (pNPX) with a concurrent 1.1-fold increase in the k(cat)/K(m) for pNP-beta-d-glucopyranoside (pNPG) was identified. Amino acid residue E115 may therefore contribute to the discrimination between beta-xylosides and beta-glucosides. Our results demonstrate that each of the four GH3 enzymes has evolved to perform a specific role in lignopolysaccharide hydrolysis and provide insight into the role of active-site residues in catalysis and substrate specificity for GH3 enzymes.
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Characterization and kinetic analysis of a thermostable GH3 beta-glucosidase from Penicillium brasilianum. Appl Microbiol Biotechnol 2009; 86:143-54. [PMID: 19756584 DOI: 10.1007/s00253-009-2181-7] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2009] [Revised: 08/04/2009] [Accepted: 08/04/2009] [Indexed: 10/20/2022]
Abstract
A GH3 beta-glucosidase (BGL) from Penicillium brasilianum was purified to homogeneity after cultivation on a cellulose and xylan rich medium. The BGL was identified in a genomic library, and it was successfully expressed in Aspergillus oryzae. The BGL had excellent stability at elevated temperatures with no loss in activity after 24 h of incubation at 60 degrees C at pH 4-6, and the BGL was shown to have significantly higher stability at these conditions in comparison to Novozym 188 and to other fungal GH3 BGLs reported in the literature. The BGL had significant lower affinity for cellobiose compared with the artificial substrate para-nitrophenyl-beta-D-glucopyranoside (pNP-Glc) and further, pronounced substrate inhibition using pNP-Glc. Kinetic studies demonstrated the high importance of using cellobiose as substrate and glucose as inhibitor to describe the inhibition kinetics of BGL taking place during cellulose hydrolysis. A novel assay was developed to characterize this glucose inhibition on cellobiose hydrolysis. The assay uses labelled glucose-13C6 as inhibitor and subsequent mass spectrometry analysis to quantify the hydrolysis rates.
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Vasur J, Kawai R, Andersson E, Igarashi K, Sandgren M, Samejima M, Ståhlberg J. X-ray crystal structures of Phanerochaete chrysosporium Laminarinase 16A in complex with products from lichenin and laminarin hydrolysis. FEBS J 2009; 276:3858-69. [PMID: 19769746 DOI: 10.1111/j.1742-4658.2009.07099.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The 1,3(4)-beta-D-glucanases of glycoside hydrolase family 16 provide useful examples of versatile yet specific protein-carbohydrate interactions. In the present study, we report the X-ray structures of the 1,3(4)-beta-D-glucanase Phanerochaete chrysosporium Laminarinase 16A in complex with beta-glucan products from laminarin (1.6 A) and lichenin (1.1 A) hydrolysis. The G6G3G3G glucan, in complex with the enzyme, showed a beta-1,6 branch in the acceptor site. The G4G3G ligand-protein complex showed that there was no room for a beta-1,6 branch in the -1 or -2 subsites; furthermore, the distorted residue in the -1 subsite and the glucose in the -2 subsite required a beta-1,3 bond between them. These are the first X-ray crystal structures of any 1,3(4)-beta-D-glucanase in complex with glucan products. They provide details of both substrate and product binding in support of earlier enzymatic evidence.
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Affiliation(s)
- Jonas Vasur
- Department of Molecular Biology, University of Agricultural Sciences, Uppsala, Sweden
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Ishida T, Fushinobu S, Kawai R, Kitaoka M, Igarashi K, Samejima M. Crystal structure of glycoside hydrolase family 55 {beta}-1,3-glucanase from the basidiomycete Phanerochaete chrysosporium. J Biol Chem 2009; 284:10100-9. [PMID: 19193645 DOI: 10.1074/jbc.m808122200] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Glycoside hydrolase family 55 consists of beta-1,3-glucanases mainly from filamentous fungi. A beta-1,3-glucanase (Lam55A) from the Basidiomycete Phanerochaete chrysosporium hydrolyzes beta-1,3-glucans in the exo-mode with inversion of anomeric configuration and produces gentiobiose in addition to glucose from beta-1,3/1,6-glucans. Here we report the crystal structure of Lam55A, establishing the three-dimensional structure of a member of glycoside hydrolase 55 for the first time. Lam55A has two beta-helical domains in a single polypeptide chain. These two domains are separated by a long linker region but are positioned side by side, and the overall structure resembles a rib cage. In the complex, a gluconolactone molecule is bound at the bottom of a pocket between the two beta-helical domains. Based on the position of the gluconolactone molecule, Glu-633 appears to be the catalytic acid, whereas the catalytic base residue could not be identified. The substrate binding pocket appears to be able to accept a gentiobiose unit near the cleavage site, and a long cleft runs from the pocket, in accordance with the activity of this enzyme toward various beta-1,3-glucan oligosaccharides. In conclusion, we provide important features of the substrate-binding site at the interface of the two beta-helical domains, demonstrating an unexpected variety of carbohydrate binding modes.
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Affiliation(s)
- Takuya Ishida
- Departments of Biomaterials Sciences and Biotechnology, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
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40
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Deoxynojirimycin enhanced the transglycosylation activity of a glycosidase from the China white jade snail. J Biotechnol 2009; 139:229-35. [DOI: 10.1016/j.jbiotec.2008.12.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2008] [Revised: 10/31/2008] [Accepted: 12/09/2008] [Indexed: 11/22/2022]
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41
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Characterization of an endoglucanase belonging to a new subfamily of glycoside hydrolase family 45 of the basidiomycete Phanerochaete chrysosporium. Appl Environ Microbiol 2008; 74:5628-34. [PMID: 18676702 DOI: 10.1128/aem.00812-08] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The wood decay fungus Phanerochaete chrysosporium has served as a model system for the study of lignocellulose conversions, but aspects of its cellulolytic system remain uncertain. Here, we report identifying the gene that encodes the glycoside hydrolase (GH) family 45 endoglucanase (EG) from the fungus, cloning the cDNA, determining its heterologous expression in the methylotrophic yeast Pichia pastoris, and characterizing the recombinant protein. The cDNA consisted of 718 bp, including an open reading frame encoding a 19-amino-acid signal peptide, a 7-amino-acid presequence at the N-terminal region, and a 180-amino-acid mature protein, which has no cellulose binding domain. Analysis of the amino acid sequence revealed that the protein has a low similarity (<22%) to known fungal EGs belonging to the GH family 45 (EGVs). No conserved domain of this family was found by a BLAST search, suggesting that the protein should be classified into a new subdivision of this GH family. The recombinant protein has hydrolytic activity toward amorphous cellulose, carboxylmethyl cellulose, lichenan, barley beta-glucan, and glucomannan but not xylan. Moreover, a synergistic effect was observed with the recombinant GH family 6 cellobiohydrolase from the same fungus toward amorphous cellulose as a substrate, indicating that the enzyme may act in concert with other cellulolytic enzymes to hydrolyze cellulosic biomass in nature.
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42
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Hu Y, Luan H, Zhou K, Ge G, Yang S, Yang L. Purification and characterization of a novel glycosidase from the china white jade snail (Achatina fulica) showing transglycosylation activity. Enzyme Microb Technol 2008. [DOI: 10.1016/j.enzmictec.2008.02.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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43
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Hrmova M, Fincher GB. Dissecting the catalytic mechanism of a plant beta-D-glucan glucohydrolase through structural biology using inhibitors and substrate analogues. Carbohydr Res 2007; 342:1613-23. [PMID: 17548065 DOI: 10.1016/j.carres.2007.05.013] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2007] [Revised: 05/04/2007] [Accepted: 05/08/2007] [Indexed: 11/23/2022]
Abstract
Higher plant, family GH3 beta-D-glucan glucohydrolases exhibit exo-hydrolytic and retaining (e-->e) mechanisms of action and catalyze the removal of single glucosyl residues from the non-reducing termini of beta-D-linked glucosidic substrates, with retention of anomeric configuration. The broad specificity beta-D-glucan glucohydrolases are likely to play roles in cell wall re-modelling, turn-over of cell wall components and possibly in plant defence reactions against pathogens. Crystal structures of the barley beta-D-glucan glucohydrolase, obtained from both native enzyme and from the enzyme in complex with a substrate analogues and mechanism-based inhibitors, have enabled the basis of substrate specificity, the mechanism of catalysis, and the role of domain movements during the catalytic cycle to be defined in precise molecular terms. The active site of the enzyme forms a shallow 'pocket' that is located at the interface of two domains of the enzyme and accommodates two glucosyl residues. The propensity of the enzyme to hydrolyze a broad range of substrates with (1-->2)-, (1-->3)-, (1-->4)- and (1-->6)-beta-D-glucosidic linkages is explained from crystal structures of the enzyme in complex with non-hydrolysable S-glycoside substrate analogues, and from molecular modelling. During binding of gluco-oligosaccharides, the glucosyl residue at subsite -1 is locked in a highly constrained position, but the glucosyl residue at the +1 subsite is free to adjust its position between two tryptophan residues positioned at the entry of the active site pocket. The flexibility at subsite +1 and the projection of the remainder of the substrate away from the pocket provide a structural rationale for the capacity of the enzyme to accommodate and hydrolyze glucosides with different linkage positions and hence different overall conformations. While mechanism-based inhibitors with micromolar Ki constants bind in the active site of the enzyme and form esters with the catalytic nucleophile, transition-state mimics bind with their 'glucose' moieties distorted into the 4E conformation, which is critical for the nanomolar binding of these inhibitors to the enzyme. The glucose product of the reaction, which is released from the non-reducing termini of substrates, remains bound to the beta-D-glucan glucohydrolase in the -1 subsite of the active site, until a new substrate molecule approaches the enzyme. If dissociation of the glucose from the enzyme active site could be synchronized throughout the crystal, time-resolved Laue X-ray crystallography could be used to follow the conformational changes that occur as the glucose product diffuses away and the incoming substrate is bound by the enzyme.
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Affiliation(s)
- Maria Hrmova
- Australian Centre for Plant Functional Genomics, School of Agriculture, Food and Wine, University of Adelaide, Waite Campus, Glen Osmond, SA 5064, Australia.
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Tsukada T, Igarashi K, Yoshida M, Samejima M. Molecular cloning and characterization of two intracellular beta-glucosidases belonging to glycoside hydrolase family 1 from the basidiomycete Phanerochaete chrysosporium. Appl Microbiol Biotechnol 2006; 73:807-14. [PMID: 16896601 DOI: 10.1007/s00253-006-0526-z] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2006] [Revised: 05/30/2006] [Accepted: 06/01/2006] [Indexed: 11/25/2022]
Abstract
cDNAs encoding two glycoside hydrolase family 1 beta-glucosidases (BGL1A and BGL1B) were cloned from the basidiomycete Phanerochaete chrysosporium, and the substrate specificities of the recombinant enzymes and the expression patterns of the two genes were investigated in relation to cellobiose metabolism by the fungus. The cDNA sequences contained open reading frames of 1,389 base pairs (bp) (bgl1A) and 1,623 bp (bgl1B), encoding 462 and 530 amino acids, respectively. Although high sequence identity (65%) was observed between the deduced amino acid sequences of the two enzymes, an apparent difference was observed at the C-terminal region: BGL1B has a 63-amino acid extension, which has no similarity with any known protein. Both recombinant enzymes expressed in Escherichia coli showed hydrolytic activity towards several beta-glycosidic compounds. However, the substrate recognition patterns of the two enzymes were quite different from each other. In particular, cellobiose was hydrolyzed more effectively by BGL1B than by BGL1A. The expression of the two genes in the fungus was monitored by reverse transcription-PCR, which showed that bgl1A was expressed constitutively in both glucose- and cellobiose-containing culture, whereas bgl1B was expressed in cellobiose culture but was repressed in glucose culture, possibly because of carbon catabolite repression. We conclude that BGL1B contributes to cellobiose metabolism during cellulose degradation by P. chrysosporium.
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MESH Headings
- Amino Acid Sequence
- Cellobiose/metabolism
- Cloning, Molecular
- DNA, Complementary/genetics
- DNA, Fungal/chemistry
- DNA, Fungal/genetics
- Gene Expression Regulation, Fungal
- Glycosides/metabolism
- Kinetics
- Molecular Sequence Data
- Open Reading Frames
- Phanerochaete/enzymology
- Phanerochaete/genetics
- Protein Structure, Tertiary
- RNA, Fungal/biosynthesis
- RNA, Messenger/biosynthesis
- Recombinant Proteins/genetics
- Recombinant Proteins/isolation & purification
- Recombinant Proteins/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Sequence Analysis, DNA
- Sequence Homology, Amino Acid
- beta-Glucosidase/genetics
- beta-Glucosidase/isolation & purification
- beta-Glucosidase/metabolism
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Affiliation(s)
- Takeshi Tsukada
- Department of Biomaterials Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
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45
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Kawai R, Igarashi K, Yoshida M, Kitaoka M, Samejima M. Hydrolysis of beta-1,3/1,6-glucan by glycoside hydrolase family 16 endo-1,3(4)-beta-glucanase from the basidiomycete Phanerochaete chrysosporium. Appl Microbiol Biotechnol 2005; 71:898-906. [PMID: 16374635 DOI: 10.1007/s00253-005-0214-4] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2005] [Revised: 10/07/2005] [Accepted: 10/10/2005] [Indexed: 10/25/2022]
Abstract
When Phanerochaete chrysosporium was grown with laminarin (a beta-1,3/1,6-glucan) as the sole carbon source, a beta-1,3-glucanase with a molecular mass of 36 kDa was produced as a major extracellular protein. The cDNA encoding this enzyme was cloned, and the deduced amino acid sequence revealed that this enzyme belongs to glycoside hydrolase family 16; it was named Lam16A. Recombinant Lam16A, expressed in the methylotrophic yeast Pichia pastoris, randomly hydrolyzes linear beta-1,3-glucan, branched beta-1,3/1,6-glucan, and beta-1,3-1,4-glucan, suggesting that the enzyme is a typical endo-1,3(4)-beta-glucanase (EC 3.2.1.6) with broad substrate specificity for beta-1,3-glucans. When laminarin and lichenan were used as substrates, Lam16A produced 6-O-glucosyl-laminaritriose (beta-D-Glcp-(1->6)-beta-D-Glcp-(1->3)-beta-D-Glcp-(1->3)-D-Glc) and 4-O-glucosyl-laminaribiose (beta-D-Glcp-(1->4)-beta-D-Glcp-(1->3)-D-Glc), respectively, as one of the major products. These results suggested that the enzyme strictly recognizes beta-D-Glcp-(1->3)-D-Glcp at subsites -2 and -1, whereas it permits 6-O-glucosyl substitution at subsite +1 and a beta-1,4-glucosidic linkage at the catalytic site. Consequently, Lam16A generates non-branched oligosaccharide from branched beta-1,3/1,6-glucan and, thus, may contribute to the effective degradation of such molecules in combination with other extracellular beta-1,3-glucanases.
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Affiliation(s)
- Rie Kawai
- Department of Biomaterials Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan
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