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Teze D, Zhao J, Wiemann M, Kazi ZGA, Lupo R, Zeuner B, Vuillemin M, Rønne ME, Carlström G, Duus JØ, Sanejouand YH, O'Donohue MJ, Nordberg Karlsson E, Fauré R, Stålbrand H, Svensson B. Rational Enzyme Design without Structural Knowledge: A Sequence-Based Approach for Efficient Generation of Transglycosylases. Chemistry 2021; 27:10323-10334. [PMID: 33914359 DOI: 10.1002/chem.202100110] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Indexed: 12/22/2022]
Abstract
Glycobiology is dogged by the relative scarcity of synthetic, defined oligosaccharides. Enzyme-catalysed glycosylation using glycoside hydrolases is feasible but is hampered by the innate hydrolytic activity of these enzymes. Protein engineering is useful to remedy this, but it usually requires prior structural knowledge of the target enzyme, and/or relies on extensive, time-consuming screening and analysis. Here, a straightforward strategy that involves rational rapid in silico analysis of protein sequences is described. The method pinpoints 6-12 single-mutant candidates to improve transglycosylation yields. Requiring very little prior knowledge of the target enzyme other than its sequence, the method is generic and procures catalysts for the formation of glycosidic bonds involving various d/l-, α/β-pyranosides or furanosides, and exo or endo action. Moreover, mutations validated in one enzyme can be transposed to others, even distantly related enzymes.
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Affiliation(s)
- David Teze
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads, building 224, DK-2800, Kongens Lyngby, Denmark
| | - Jiao Zhao
- Toulouse Biotechnology Institute, Université de Toulouse, CNRS, INRAE, INSA, 135 avenue de Rangueil, 31077, Toulouse CEDEX 04, France
| | - Mathias Wiemann
- Department of Biochemistry and Structural Biology, Lund University, 221 00, Lund, Sweden
| | - Zubaida G A Kazi
- Department of Chemistry, Lund University, PO Box 124, 22100, Lund, Sweden
| | - Rossana Lupo
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads, building 224, DK-2800, Kongens Lyngby, Denmark
| | - Birgitte Zeuner
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads, building 224, DK-2800, Kongens Lyngby, Denmark
| | - Marlène Vuillemin
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads, building 224, DK-2800, Kongens Lyngby, Denmark
| | - Mette E Rønne
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads, building 224, DK-2800, Kongens Lyngby, Denmark
| | - Göran Carlström
- Department of Chemistry, Lund University, PO Box 124, 22100, Lund, Sweden
| | - Jens Ø Duus
- Department of Chemistry, Technical University of Denmark, Kemitorvet, bulding 207, DK-2800, Kongens Lyngby, Denmark
| | - Yves-Henri Sanejouand
- UFIP, UMR 6286, Université de Nantes, CNRS, 2, chemin de la Houssiniere, Nantes, France
| | - Michael J O'Donohue
- Toulouse Biotechnology Institute, Université de Toulouse, CNRS, INRAE, INSA, 135 avenue de Rangueil, 31077, Toulouse CEDEX 04, France
| | | | - Régis Fauré
- Toulouse Biotechnology Institute, Université de Toulouse, CNRS, INRAE, INSA, 135 avenue de Rangueil, 31077, Toulouse CEDEX 04, France
| | - Henrik Stålbrand
- Department of Biochemistry and Structural Biology, Lund University, 221 00, Lund, Sweden
| | - Birte Svensson
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads, building 224, DK-2800, Kongens Lyngby, Denmark
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2
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Eneyskaya EV, Bobrov KS, Kashina MV, Borisova AS, Kulminskaya AA. A novel acid-tolerant β-xylanase from Scytalidium candidum 3C for the synthesis of o-nitrophenyl xylooligosaccharides. J Basic Microbiol 2020; 60:971-982. [PMID: 33103248 DOI: 10.1002/jobm.202000303] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Revised: 08/31/2020] [Accepted: 09/15/2020] [Indexed: 11/06/2022]
Abstract
Endo-β-xylanases are hemicellulases involved in the conversion of xylans in plant biomass. Here, we report a novel acidophilic β-xylanase (ScXynA) with high transglycosylation abilities that was isolated from the filamentous fungus Scytalidium candidum 3C. ScXynA was identified as a glycoside hydrolase family 10 (GH10) dimeric protein, with a molecular weight of 38 ± 5 kDa per subunit. The enzyme catalyzed the hydrolysis of different xylans under acidic conditions and was stable in the pH range 2.6-4.5. The kinetic parameters of ScXynA were determined in hydrolysis reactions with p-nitrophenyl-β-d-cellobioside (pNP-β-Cel) and p-nitrophenyl-β-d-xylobioside (pNP-β-Xyl2 ), and kcat /Km was found to be 0.43 ± 0.02 (s·mM)-1 and 57 ± 3 (s·mM)-1 , respectively. In the catalysis of the transglycosylation o-nitrophenyl-β-d-xylobioside (oNP-β-Xyl2 ) acted both as a donor and an acceptor, resulting in the efficient production of o-nitrophenyl xylooligosaccharides, with a degree of polymerization of 3-10 and o-nitrophenyl-β-d-xylotetraose (oNP-β-Xyl4 ) as the major product (18.5% yield). The modeled ScXynA structure showed a favorable position for ligand entry and o-nitrophenyl group accommodation in the relatively open -3 subsite, while the cleavage site was covered with an extended loop. These structural features provide favorable conditions for transglycosylation with oNP-β-Xyl2 . The acidophilic properties and high transglycosylation activity make ScXynA a suitable choice for various biotechnological applications, including the synthesis of valuable xylooligosaccharides.
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Affiliation(s)
- Elena V Eneyskaya
- Molecular and Radiation Biophysics Division, Petersburg Nuclear Physics Institute named by B.P. Konstantinov of National Research Center, Kurchatov Institute, Gatchina, Leningrad Region, Russia.,Kurchatov Genome Center - PNPI, Gatchina, Leningrad Region, Russia
| | - Kirill S Bobrov
- Molecular and Radiation Biophysics Division, Petersburg Nuclear Physics Institute named by B.P. Konstantinov of National Research Center, Kurchatov Institute, Gatchina, Leningrad Region, Russia.,Kurchatov Genome Center - PNPI, Gatchina, Leningrad Region, Russia
| | - Maria V Kashina
- Institute of Chemistry, St. Petersburg State University, St. Petersburg, Russia
| | - Anna S Borisova
- Molecular and Radiation Biophysics Division, Petersburg Nuclear Physics Institute named by B.P. Konstantinov of National Research Center, Kurchatov Institute, Gatchina, Leningrad Region, Russia.,VTT Technical Research Center of Finland Ltd., Otaniemi, Finland
| | - Anna A Kulminskaya
- Molecular and Radiation Biophysics Division, Petersburg Nuclear Physics Institute named by B.P. Konstantinov of National Research Center, Kurchatov Institute, Gatchina, Leningrad Region, Russia.,Kurchatov Genome Center - PNPI, Gatchina, Leningrad Region, Russia
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3
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Yang J, Ma T, Shang-Guan F, Han Z. Improving the catalytic activity of thermostable xylanase from Thermotoga maritima via mutagenesis of non-catalytic residues at glycone subsites. Enzyme Microb Technol 2020; 139:109579. [PMID: 32732029 DOI: 10.1016/j.enzmictec.2020.109579] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Revised: 03/31/2020] [Accepted: 04/14/2020] [Indexed: 10/24/2022]
Abstract
Endo-β-1,4-xylanase from Thermotoga maritima, TmxB, is an industrially attractive enzyme due to its extreme thermostability. To improve its application value, four variants were designed on the basis of multiple sequence and three-dimensional structure alignments. Wild-type TmxB (wt-TmxB) and its mutants were produced via a Pichia pastoris expression system. Among four single-site mutants, the tyrosine substitution of a threonine residue (T74Y) at putative -3/-4 subsite led to a 1.3-fold increase in specific activity at 40 °C - 100 °C and pH 5 for 5 min, with beechwood xylan as the substrate. T74Y had an improved catalytic efficiency (kcat/Km), being 1.6 times that of wt-TmxB. Variants DY (two amino acid insertions) and N68Q displayed a slight increase (1.2 fold) and dramatic decline (1.7 fold) in catalytic efficiency, respectively. Mutant E67Y was totally inactive under all test conditions. Structural modeling and docking simulation elucidated structural insights into the molecular mechanism of activity changes for these TmxB variants. This study helps in further understanding the roles of the non-catalytic amino acids at the glycone subsites of xylanases from glycoside hydrolase family 10.
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Affiliation(s)
- Jiangke Yang
- College of Biology and Pharmaceutical Engineering, Wuhan Polytechnic University, Wuhan 430023, China
| | - Tengfei Ma
- School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Fang Shang-Guan
- College of Biology and Pharmaceutical Engineering, Wuhan Polytechnic University, Wuhan 430023, China
| | - Zhenggang Han
- College of Biology and Pharmaceutical Engineering, Wuhan Polytechnic University, Wuhan 430023, China.
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4
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Complex N-glycan breakdown by gut Bacteroides involves an extensive enzymatic apparatus encoded by multiple co-regulated genetic loci. Nat Microbiol 2019; 4:1571-1581. [PMID: 31160824 DOI: 10.1038/s41564-019-0466-x] [Citation(s) in RCA: 93] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Accepted: 04/24/2019] [Indexed: 02/08/2023]
Abstract
Glycans are the major carbon sources available to the human colonic microbiota. Numerous N-glycosylated proteins are found in the human gut, from both dietary and host sources, including immunoglobulins such as IgA that are secreted into the intestine at high levels. Here, we show that many mutualistic gut Bacteroides spp. have the capacity to utilize complex N-glycans (CNGs) as nutrients, including those from immunoglobulins. Detailed mechanistic studies using transcriptomic, biochemical, structural and genetic techniques reveal the pathway employed by Bacteroides thetaiotaomicron (Bt) for CNG degradation. The breakdown process involves an extensive enzymatic apparatus encoded by multiple non-adjacent loci and comprises 19 different carbohydrate-active enzymes from different families, including a CNG-specific endo-glycosidase activity. Furthermore, CNG degradation involves the activity of carbohydrate-active enzymes that have previously been implicated in the degradation of other classes of glycan. This complex and diverse apparatus provides Bt with the capacity to access the myriad different structural variants of CNGs likely to be found in the intestinal niche.
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Multiple exo-glycosidases in human serum as detected with the substrate DNP-α-GalNAc. I. A new assay for lysosomal α- N-acetylgalactosaminidase. BBA CLINICAL 2017; 8:84-89. [PMID: 29062717 PMCID: PMC5645117 DOI: 10.1016/j.bbacli.2017.10.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
This paper presents a new assay to determine the activity of the lysosomal enzyme α-N-acetylgalactosaminidase (Naga, EC 3.2.1.49) in human serum. It is based on the use of a new chromogenic substrate, DNP-α-GalNAc (2,4-dinitrophenyl-N-acetyl-α-D-galactosaminide) and is performed at pH 4.3 and 37 °C. This allows continuous monitoring of the absorbance of the released DNP. The assay can be performed with a standard spectrophotometer. Compared to established methods using an endpoint assay with MU-α-GalNAc (4-methylumbelliferyl-GalNAc), the present method gives a ca. 3-fold higher specific activity, while only one tenth of the serum concentration in the assay is required. Hence, the assay is at least 30-fold more sensitive than that with MU-α-GalNAc. The pH dependence of the reaction with DNP-α-GalNAc in the pH 3.5 to 6.5 region, while using 4% serum in the assay, shows only one peak around pH 4. This pH optimum is similar to that reported with MU-α-GalNAc. In the accompanying paper (S.P.J Albracht and J. Van Pelt (2017) Multiple exo-glycosidases in human serum as detected with the substrate DNP-α-GalNAc. II. Three α-N-acetylgalactosaminidase-like activities in the pH 5 to 8 region. BBA Clin. 8 (2017) 90-96), the method is used to show that, under special assay conditions, three more Naga-like activities can be uncovered in human serum.
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Key Words
- A380, optical absorbance at 380 nm
- DMF, dimethylformamide
- DMSO, dimethylsulphoxide
- DNP-α-GalNAc
- DNP-α-GalNAc, 2,4-dinitrophenyl-N-acetyl-α-D-galactosaminide
- DNPH, 2,4-dinitrophenol
- DNP−, 2,4-dinitrophenolate
- Gla, α-galactosidase A
- Lysosomes
- MU, 4-methylumbelliferone
- Naga
- Naga, α-N-acetylgalactosaminidase
- New assay
- RT, room temperature
- S.A., specific activity in nmol substrate per min per mL serum (nmol·min− 1·mL− 1), using 2 mM DNP-α-GalNAc
- Schindler disease
- pNP-α-GalNAc, para-nitrophenyl-α-GalNAc
- α-GalNAc, N-acetyl-α-D-galactosaminide
- α-N-acetylgalactosaminidase
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6
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Labourel A, Crouch LI, Brás JLA, Jackson A, Rogowski A, Gray J, Yadav MP, Henrissat B, Fontes CMGA, Gilbert HJ, Najmudin S, Baslé A, Cuskin F. The Mechanism by Which Arabinoxylanases Can Recognize Highly Decorated Xylans. J Biol Chem 2016; 291:22149-22159. [PMID: 27531750 PMCID: PMC5063996 DOI: 10.1074/jbc.m116.743948] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2016] [Indexed: 12/15/2022] Open
Abstract
The enzymatic degradation of plant cell walls is an important biological process of increasing environmental and industrial significance. Xylan, a major component of the plant cell wall, consists of a backbone of β-1,4-xylose (Xylp) units that are often decorated with arabinofuranose (Araf) side chains. A large penta-modular enzyme, CtXyl5A, was shown previously to specifically target arabinoxylans. The mechanism of substrate recognition displayed by the enzyme, however, remains unclear. Here we report the crystal structure of the arabinoxylanase and the enzyme in complex with ligands. The data showed that four of the protein modules adopt a rigid structure, which stabilizes the catalytic domain. The C-terminal non-catalytic carbohydrate binding module could not be observed in the crystal structure, suggesting positional flexibility. The structure of the enzyme in complex with Xylp-β-1,4-Xylp-β-1,4-Xylp-[α-1,3-Araf]-β-1,4-Xylp showed that the Araf decoration linked O3 to the xylose in the active site is located in the pocket (−2* subsite) that abuts onto the catalytic center. The −2* subsite can also bind to Xylp and Arap, explaining why the enzyme can utilize xylose and arabinose as specificity determinants. Alanine substitution of Glu68, Tyr92, or Asn139, which interact with arabinose and xylose side chains at the −2* subsite, abrogates catalytic activity. Distal to the active site, the xylan backbone makes limited apolar contacts with the enzyme, and the hydroxyls are solvent-exposed. This explains why CtXyl5A is capable of hydrolyzing xylans that are extensively decorated and that are recalcitrant to classic endo-xylanase attack.
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Affiliation(s)
- Aurore Labourel
- From the Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom
| | - Lucy I Crouch
- From the Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom
| | - Joana L A Brás
- CIISA-Faculdade de Medicina Veterinária, Universidade de Lisboa, Pólo Universitário do Alto da Ajuda, Avenida da Universidade Técnica, 1300-477 Lisboa, Portugal, NZYTech Genes & Enzymes, 1649-038 Lisboa, Portugal
| | - Adam Jackson
- From the Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom
| | - Artur Rogowski
- From the Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom
| | - Joseph Gray
- From the Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom
| | - Madhav P Yadav
- the Eastern Regional Research Center, United States Department of Agriculture-Agricultural Research Service, Wyndmoor, Pennsylvania 19038
| | - Bernard Henrissat
- Architecture et Fonction des Macromolécules Biologiques, UMR7857 CNRS, Aix-Marseille University, F-13288 Marseille, France, USC1408 Architecture et Fonction des Macromolécules Biologiques, INRA, F-13288 Marseille, France, and the Department of Biological Sciences, King Abdulaziz University, Jedda 21589, Saudi Arabia
| | - Carlos M G A Fontes
- CIISA-Faculdade de Medicina Veterinária, Universidade de Lisboa, Pólo Universitário do Alto da Ajuda, Avenida da Universidade Técnica, 1300-477 Lisboa, Portugal, NZYTech Genes & Enzymes, 1649-038 Lisboa, Portugal
| | - Harry J Gilbert
- From the Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom
| | - Shabir Najmudin
- CIISA-Faculdade de Medicina Veterinária, Universidade de Lisboa, Pólo Universitário do Alto da Ajuda, Avenida da Universidade Técnica, 1300-477 Lisboa, Portugal,
| | - Arnaud Baslé
- From the Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom,
| | - Fiona Cuskin
- From the Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom,
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7
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Gardner JG. Polysaccharide degradation systems of the saprophytic bacterium Cellvibrio japonicus. World J Microbiol Biotechnol 2016; 32:121. [PMID: 27263016 DOI: 10.1007/s11274-016-2068-6] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2016] [Accepted: 04/07/2016] [Indexed: 01/10/2023]
Abstract
Study of recalcitrant polysaccharide degradation by bacterial systems is critical for understanding biological processes such as global carbon cycling, nutritional contributions of the human gut microbiome, and the production of renewable fuels and chemicals. One bacterium that has a robust ability to degrade polysaccharides is the Gram-negative saprophyte Cellvibrio japonicus. A bacterium with a circuitous history, C. japonicus underwent several taxonomy changes from an initially described Pseudomonas sp. Most of the enzymes described in the pre-genomics era have also been renamed. This review aims to consolidate the biochemical, structural, and genetic data published on C. japonicus and its remarkable ability to degrade cellulose, xylan, and pectin substrates. Initially, C. japonicus carbohydrate-active enzymes were studied biochemically and structurally for their novel polysaccharide binding and degradation characteristics, while more recent systems biology approaches have begun to unravel the complex regulation required for lignocellulose degradation in an environmental context. Also included is a discussion for the future of C. japonicus as a model system, with emphasis on current areas unexplored in terms of polysaccharide degradation and emerging directions for C. japonicus in both environmental and biotechnological applications.
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Affiliation(s)
- Jeffrey G Gardner
- Department of Biological Sciences, University of Maryland - Baltimore County, Baltimore, MD, USA.
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8
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Zheng F, Huang J, Liu X, Hu H, Long L, Chen K, Ding S. N- and C-terminal truncations of a GH10 xylanase significantly increase its activity and thermostability but decrease its SDS resistance. Appl Microbiol Biotechnol 2015; 100:3555-65. [DOI: 10.1007/s00253-015-7176-y] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2015] [Revised: 11/09/2015] [Accepted: 11/13/2015] [Indexed: 11/28/2022]
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9
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Cuskin F, Baslé A, Ladevèze S, Day AM, Gilbert HJ, Davies GJ, Potocki-Véronèse G, Lowe EC. The GH130 Family of Mannoside Phosphorylases Contains Glycoside Hydrolases That Target β-1,2-Mannosidic Linkages in Candida Mannan. J Biol Chem 2015; 290:25023-33. [PMID: 26286752 PMCID: PMC4599007 DOI: 10.1074/jbc.m115.681460] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Revised: 08/12/2015] [Indexed: 11/06/2022] Open
Abstract
The depolymerization of complex glycans is an important biological process that is of considerable interest to environmentally relevant industries. β-Mannose is a major component of plant structural polysaccharides and eukaryotic N-glycans. These linkages are primarily cleaved by glycoside hydrolases, although recently, a family of glycoside phosphorylases, GH130, have also been shown to target β-1,2- and β-1,4-mannosidic linkages. In these phosphorylases, bond cleavage was mediated by a single displacement reaction in which phosphate functions as the catalytic nucleophile. A cohort of GH130 enzymes, however, lack the conserved basic residues that bind the phosphate nucleophile, and it was proposed that these enzymes function as glycoside hydrolases. Here we show that two Bacteroides enzymes, BT3780 and BACOVA_03624, which lack the phosphate binding residues, are indeed β-mannosidases that hydrolyze β-1,2-mannosidic linkages through an inverting mechanism. Because the genes encoding these enzymes are located in genetic loci that orchestrate the depolymerization of yeast α-mannans, it is likely that the two enzymes target the β-1,2-mannose residues that cap the glycan produced by Candida albicans. The crystal structure of BT3780 in complex with mannose bound in the -1 and +1 subsites showed that a pair of glutamates, Glu(227) and Glu(268), hydrogen bond to O1 of α-mannose, and either of these residues may function as the catalytic base. The candidate catalytic acid and the other residues that interact with the active site mannose are conserved in both GH130 mannoside phosphorylases and β-1,2-mannosidases. Functional phylogeny identified a conserved lysine, Lys(199) in BT3780, as a key specificity determinant for β-1,2-mannosidic linkages.
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Affiliation(s)
- Fiona Cuskin
- From the Institute for Cell and Molecular Biosciences, Medical School Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom
| | - Arnaud Baslé
- From the Institute for Cell and Molecular Biosciences, Medical School Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom
| | - Simon Ladevèze
- Université de Toulouse, INSA/UPS/INP, LISBP, F-31077 Toulouse, France, CNRS, UMR5504 and INRA, UMR792 Ingénierie des Systèmes Biologiques et des Procédés, F-31400 Toulouse, France, and
| | - Alison M Day
- From the Institute for Cell and Molecular Biosciences, Medical School Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom
| | - Harry J Gilbert
- From the Institute for Cell and Molecular Biosciences, Medical School Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom,
| | - Gideon J Davies
- the York Structural Biology Laboratory, Department of Chemistry, University of York, York YO10 5DD, United Kingdom
| | - Gabrielle Potocki-Véronèse
- Université de Toulouse, INSA/UPS/INP, LISBP, F-31077 Toulouse, France, CNRS, UMR5504 and INRA, UMR792 Ingénierie des Systèmes Biologiques et des Procédés, F-31400 Toulouse, France, and
| | - Elisabeth C Lowe
- From the Institute for Cell and Molecular Biosciences, Medical School Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom,
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10
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Glycan complexity dictates microbial resource allocation in the large intestine. Nat Commun 2015; 6:7481. [PMID: 26112186 PMCID: PMC4491172 DOI: 10.1038/ncomms8481] [Citation(s) in RCA: 276] [Impact Index Per Article: 30.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Accepted: 05/13/2015] [Indexed: 12/20/2022] Open
Abstract
The structure of the human gut microbiota is controlled primarily through the degradation of complex dietary carbohydrates, but the extent to which carbohydrate breakdown products are shared between members of the microbiota is unclear. We show here, using xylan as a model, that sharing the breakdown products of complex carbohydrates by key members of the microbiota, such as Bacteroides ovatus, is dependent on the complexity of the target glycan. Characterization of the extensive xylan degrading apparatus expressed by B. ovatus reveals that the breakdown of the polysaccharide by the human gut microbiota is significantly more complex than previous models suggested, which were based on the deconstruction of xylans containing limited monosaccharide side chains. Our report presents a highly complex and dynamic xylan degrading apparatus that is fine-tuned to recognize the different forms of the polysaccharide presented to the human gut microbiota. The human gut microbiota helps us to degrade complex dietary carbohydrates such as xylan and, in turn, the carbohydrate breakdown products control the structure of the microbiota. Here the authors characterize the xylan-degrading apparatus of a key member of the gut microbiota, Bacteroides ovatus.
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11
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Cuskin F, Lowe EC, Temple MJ, Zhu Y, Cameron E, Pudlo NA, Porter NT, Urs K, Thompson AJ, Cartmell A, Rogowski A, Hamilton BS, Chen R, Tolbert TJ, Piens K, Bracke D, Vervecken W, Hakki Z, Speciale G, Munōz-Munōz JL, Day A, Peña MJ, McLean R, Suits MD, Boraston AB, Atherly T, Ziemer CJ, Williams SJ, Davies GJ, Abbott DW, Martens EC, Gilbert HJ. Human gut Bacteroidetes can utilize yeast mannan through a selfish mechanism. Nature 2015; 517:165-169. [PMID: 25567280 PMCID: PMC4978465 DOI: 10.1038/nature13995] [Citation(s) in RCA: 358] [Impact Index Per Article: 39.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Accepted: 10/22/2014] [Indexed: 12/28/2022]
Abstract
Yeasts, which have been a component of the human diet for at least 7,000 years, possess an elaborate cell wall α-mannan. The influence of yeast mannan on the ecology of the human microbiota is unknown. Here we show that yeast α-mannan is a viable food source for the Gram-negative bacterium Bacteroides thetaiotaomicron, a dominant member of the microbiota. Detailed biochemical analysis and targeted gene disruption studies support a model whereby limited cleavage of α-mannan on the surface generates large oligosaccharides that are subsequently depolymerized to mannose by the action of periplasmic enzymes. Co-culturing studies showed that metabolism of yeast mannan by B. thetaiotaomicron presents a 'selfish' model for the catabolism of this difficult to breakdown polysaccharide. Genomic comparison with B. thetaiotaomicron in conjunction with cell culture studies show that a cohort of highly successful members of the microbiota has evolved to consume sterically-restricted yeast glycans, an adaptation that may reflect the incorporation of eukaryotic microorganisms into the human diet.
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Affiliation(s)
- Fiona Cuskin
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
- Complex Carbohydrate Research Center, The University of Georgia, 315 Riverbend Road, Athens, GA 30602, USA
| | - Elisabeth C. Lowe
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
| | - Max J. Temple
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
| | - Yanping Zhu
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
- Complex Carbohydrate Research Center, The University of Georgia, 315 Riverbend Road, Athens, GA 30602, USA
| | - Elizabeth Cameron
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Nicholas A. Pudlo
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Nathan T. Porter
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Karthik Urs
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI, USA
| | | | - Alan Cartmell
- School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Artur Rogowski
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
| | - Brian S. Hamilton
- Dept. of Pharmaceutical Chemistry, University of Kansas School of Pharmacy, 2095 Constant Ave, Lawrence, KS 66047, USA
| | - Rui Chen
- Dept. of Pharmaceutical Chemistry, University of Kansas School of Pharmacy, 2095 Constant Ave, Lawrence, KS 66047, USA
| | - Thomas J. Tolbert
- Dept. of Pharmaceutical Chemistry, University of Kansas School of Pharmacy, 2095 Constant Ave, Lawrence, KS 66047, USA
| | | | | | | | - Zalihe Hakki
- School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Gaetano Speciale
- School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Jose L. Munōz-Munōz
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
| | - Andrew Day
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
| | - Maria J. Peña
- Complex Carbohydrate Research Center, The University of Georgia, 315 Riverbend Road, Athens, GA 30602, USA
| | - Richard McLean
- Agriculture and Agri-Food Canada, Lethbridge Research Centre, Lethbridge, AB, Canada
| | - Michael D. Suits
- Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada
| | - Alisdair B. Boraston
- Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada
| | - Todd Atherly
- USDA, Agricultural Research Service, National Laboratory for Agriculture and the Environment, Ames, Iowa, USA
| | - Cherie J. Ziemer
- USDA, Agricultural Research Service, National Laboratory for Agriculture and the Environment, Ames, Iowa, USA
| | - Spencer J. Williams
- School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria 3010, Australia
| | | | - D. Wade Abbott
- Complex Carbohydrate Research Center, The University of Georgia, 315 Riverbend Road, Athens, GA 30602, USA
- Agriculture and Agri-Food Canada, Lethbridge Research Centre, Lethbridge, AB, Canada
| | - Eric C. Martens
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Harry J. Gilbert
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
- Complex Carbohydrate Research Center, The University of Georgia, 315 Riverbend Road, Athens, GA 30602, USA
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12
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Derba-Maceluch M, Awano T, Takahashi J, Lucenius J, Ratke C, Kontro I, Busse-Wicher M, Kosik O, Tanaka R, Winzéll A, Kallas Å, Leśniewska J, Berthold F, Immerzeel P, Teeri TT, Ezcurra I, Dupree P, Serimaa R, Mellerowicz EJ. Suppression of xylan endotransglycosylase PtxtXyn10A affects cellulose microfibril angle in secondary wall in aspen wood. THE NEW PHYTOLOGIST 2015; 205:666-81. [PMID: 25307149 DOI: 10.1111/nph.13099] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Accepted: 08/25/2014] [Indexed: 05/02/2023]
Abstract
Certain xylanases from family GH10 are highly expressed during secondary wall deposition, but their function is unknown. We carried out functional analyses of the secondary-wall specific PtxtXyn10A in hybrid aspen (Populus tremula × tremuloides). PtxtXyn10A function was analysed by expression studies, overexpression in Arabidopsis protoplasts and by downregulation in aspen. PtxtXyn10A overexpression in Arabidopsis protoplasts resulted in increased xylan endotransglycosylation rather than hydrolysis. In aspen, the enzyme was found to be proteolytically processed to a 68 kDa peptide and residing in cell walls. Its downregulation resulted in a corresponding decrease in xylan endotransglycosylase activity and no change in xylanase activity. This did not alter xylan molecular weight or its branching pattern but affected the cellulose-microfibril angle in wood fibres, increased primary growth (stem elongation, leaf formation and enlargement) and reduced the tendency to form tension wood. Transcriptomes of transgenic plants showed downregulation of tension wood related genes and changes in stress-responsive genes. The data indicate that PtxtXyn10A acts as a xylan endotransglycosylase and its main function is to release tensional stresses arising during secondary wall deposition. Furthermore, they suggest that regulation of stresses in secondary walls plays a vital role in plant development.
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Affiliation(s)
- Marta Derba-Maceluch
- Department of Forest Genetics and Plant Physiology, SLU, Umeå Plant Science Centre (UPSC), Umeå, Sweden
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13
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Kim MK, An YJ, Song JM, Jeong CS, Kang MH, Kwon KK, Lee YH, Cha SS. Structure-based investigation into the functional roles of the extended loop and substrate-recognition sites in an endo-β-1,4-d-mannanase from the Antarctic springtail,Cryptopygus antarcticus. Proteins 2014; 82:3217-23. [DOI: 10.1002/prot.24655] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2014] [Revised: 07/15/2014] [Accepted: 07/21/2014] [Indexed: 11/09/2022]
Affiliation(s)
- Min-Kyu Kim
- Marine Biotechnology Research Division; Korea Institute of Ocean Science and Technology; Ansan 426-744 Republic of Korea
| | - Young Jun An
- Marine Biotechnology Research Division; Korea Institute of Ocean Science and Technology; Ansan 426-744 Republic of Korea
| | - Jung Min Song
- Marine Ecosystem Research Division; Korea Institute of Ocean Science and Technology; Ansan 426-744 Republic of Korea
| | - Chang-Sook Jeong
- Marine Biotechnology Research Division; Korea Institute of Ocean Science and Technology; Ansan 426-744 Republic of Korea
| | - Mee Hye Kang
- Marine Ecosystem Research Division; Korea Institute of Ocean Science and Technology; Ansan 426-744 Republic of Korea
| | - Kae Kyoung Kwon
- Marine Biotechnology Research Division; Korea Institute of Ocean Science and Technology; Ansan 426-744 Republic of Korea
| | - Youn-Ho Lee
- Marine Ecosystem Research Division; Korea Institute of Ocean Science and Technology; Ansan 426-744 Republic of Korea
| | - Sun-Shin Cha
- Marine Biotechnology Research Division; Korea Institute of Ocean Science and Technology; Ansan 426-744 Republic of Korea
- Department of Convergence Study on the Ocean Science and Technology, Ocean Science and Technology School; Korea Maritime and Ocean University; Pusan 606-791 Republic of Korea
- Department of Marine Biotechnology; University of Science and Technology; DaeJeon 305-333 Republic of Korea
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14
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Nagao C, Nagano N, Mizuguchi K. Prediction of detailed enzyme functions and identification of specificity determining residues by random forests. PLoS One 2014; 9:e84623. [PMID: 24416252 PMCID: PMC3885575 DOI: 10.1371/journal.pone.0084623] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Accepted: 11/15/2013] [Indexed: 12/03/2022] Open
Abstract
Determining enzyme functions is essential for a thorough understanding of cellular processes. Although many prediction methods have been developed, it remains a significant challenge to predict enzyme functions at the fourth-digit level of the Enzyme Commission numbers. Functional specificity of enzymes often changes drastically by mutations of a small number of residues and therefore, information about these critical residues can potentially help discriminate detailed functions. However, because these residues must be identified by mutagenesis experiments, the available information is limited, and the lack of experimentally verified specificity determining residues (SDRs) has hindered the development of detailed function prediction methods and computational identification of SDRs. Here we present a novel method for predicting enzyme functions by random forests, EFPrf, along with a set of putative SDRs, the random forests derived SDRs (rf-SDRs). EFPrf consists of a set of binary predictors for enzymes in each CATH superfamily and the rf-SDRs are the residue positions corresponding to the most highly contributing attributes obtained from each predictor. EFPrf showed a precision of 0.98 and a recall of 0.89 in a cross-validated benchmark assessment. The rf-SDRs included many residues, whose importance for specificity had been validated experimentally. The analysis of the rf-SDRs revealed both a general tendency that functionally diverged superfamilies tend to include more active site residues in their rf-SDRs than in less diverged superfamilies, and superfamily-specific conservation patterns of each functional residue. EFPrf and the rf-SDRs will be an effective tool for annotating enzyme functions and for understanding how enzyme functions have diverged within each superfamily.
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Affiliation(s)
- Chioko Nagao
- National Institute of Biomedical Innovation, Ibaraki, Osaka, Japan
- * E-mail: (CN); (KM)
| | - Nozomi Nagano
- Computational Biology Research Center, AIST, Koto-ku, Tokyo, Japan
| | - Kenji Mizuguchi
- National Institute of Biomedical Innovation, Ibaraki, Osaka, Japan
- * E-mail: (CN); (KM)
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15
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Alvarez TM, Goldbeck R, dos Santos CR, Paixão DAA, Gonçalves TA, Franco Cairo JPL, Almeida RF, de Oliveira Pereira I, Jackson G, Cota J, Büchli F, Citadini AP, Ruller R, Polo CC, de Oliveira Neto M, Murakami MT, Squina FM. Development and biotechnological application of a novel endoxylanase family GH10 identified from sugarcane soil metagenome. PLoS One 2013; 8:e70014. [PMID: 23922891 PMCID: PMC3726488 DOI: 10.1371/journal.pone.0070014] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2013] [Accepted: 06/13/2013] [Indexed: 01/26/2023] Open
Abstract
Metagenomics has been widely employed for discovery of new enzymes and pathways to conversion of lignocellulosic biomass to fuels and chemicals. In this context, the present study reports the isolation, recombinant expression, biochemical and structural characterization of a novel endoxylanase family GH10 (SCXyl) identified from sugarcane soil metagenome. The recombinant SCXyl was highly active against xylan from beechwood and showed optimal enzyme activity at pH 6,0 and 45°C. The crystal structure was solved at 2.75 Å resolution, revealing the classical (β/α)8-barrel fold with a conserved active-site pocket and an inherent flexibility of the Trp281-Arg291 loop that can adopt distinct conformational states depending on substrate binding. The capillary electrophoresis analysis of degradation products evidenced that the enzyme displays unusual capacity to degrade small xylooligosaccharides, such as xylotriose, which is consistent to the hydrophobic contacts at the +1 subsite and low-binding energies of subsites that are distant from the site of hydrolysis. The main reaction products from xylan polymers and phosphoric acid-pretreated sugarcane bagasse (PASB) were xylooligosaccharides, but, after a longer incubation time, xylobiose and xylose were also formed. Moreover, the use of SCXyl as pre-treatment step of PASB, prior to the addition of commercial cellulolytic cocktail, significantly enhanced the saccharification process. All these characteristics demonstrate the advantageous application of this enzyme in several biotechnological processes in food and feed industry and also in the enzymatic pretreatment of biomass for feedstock and ethanol production.
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Affiliation(s)
- Thabata M. Alvarez
- Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais (CNPEM), Campinas, São Paulo, Brasil
- Departamento de Bioquímica, Instituto de Biologia (IB), Universidade Estadual de Campinas (UNICAMP), Campinas, São Paulo, Brasil
| | - Rosana Goldbeck
- Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais (CNPEM), Campinas, São Paulo, Brasil
| | - Camila Ramos dos Santos
- Laboratório Nacional de Biociências (LNBio), Centro Nacional de Pesquisa em Energia e Materiais (CNPEM), Campinas, São Paulo, Brasil
| | - Douglas A. A. Paixão
- Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais (CNPEM), Campinas, São Paulo, Brasil
| | - Thiago A. Gonçalves
- Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais (CNPEM), Campinas, São Paulo, Brasil
- Departamento de Bioquímica, Instituto de Biologia (IB), Universidade Estadual de Campinas (UNICAMP), Campinas, São Paulo, Brasil
| | - João Paulo L. Franco Cairo
- Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais (CNPEM), Campinas, São Paulo, Brasil
- Departamento de Bioquímica, Instituto de Biologia (IB), Universidade Estadual de Campinas (UNICAMP), Campinas, São Paulo, Brasil
| | - Rodrigo Ferreira Almeida
- Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais (CNPEM), Campinas, São Paulo, Brasil
| | - Isabela de Oliveira Pereira
- Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais (CNPEM), Campinas, São Paulo, Brasil
| | - George Jackson
- Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais (CNPEM), Campinas, São Paulo, Brasil
| | - Junio Cota
- Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais (CNPEM), Campinas, São Paulo, Brasil
| | - Fernanda Büchli
- Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais (CNPEM), Campinas, São Paulo, Brasil
- Departamento de Bioquímica, Instituto de Biologia (IB), Universidade Estadual de Campinas (UNICAMP), Campinas, São Paulo, Brasil
| | - Ana Paula Citadini
- Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais (CNPEM), Campinas, São Paulo, Brasil
| | - Roberto Ruller
- Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais (CNPEM), Campinas, São Paulo, Brasil
| | - Carla Cristina Polo
- Laboratório Nacional de Biociências (LNBio), Centro Nacional de Pesquisa em Energia e Materiais (CNPEM), Campinas, São Paulo, Brasil
| | - Mario de Oliveira Neto
- Departamento de Física e Biofísica, Instituto de Biociências, Universidade Estadual Paulista (UNESP), Botucatu, São Paulo, Brasil
| | - Mário T. Murakami
- Laboratório Nacional de Biociências (LNBio), Centro Nacional de Pesquisa em Energia e Materiais (CNPEM), Campinas, São Paulo, Brasil
- * E-mail: (FMS); (MTM)
| | - Fabio M. Squina
- Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais (CNPEM), Campinas, São Paulo, Brasil
- * E-mail: (FMS); (MTM)
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16
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Novel structural features of xylanase A1 from Paenibacillus sp. JDR-2. J Struct Biol 2012; 180:303-11. [PMID: 23000703 DOI: 10.1016/j.jsb.2012.09.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2012] [Revised: 08/28/2012] [Accepted: 09/03/2012] [Indexed: 11/24/2022]
Abstract
The Gram-positive bacterium Paenibacillus sp. JDR-2 (PbJDR2) has been shown to have novel properties in the utilization of the abundant but chemically complex hemicellulosic sugar glucuronoxylan. Xylanase A1 of PbJDR2 (PbXynA1) has been implicated in an efficient process in which extracellular depolymerization of this polysaccharide is coupled to assimilation and intracellular metabolism. PbXynA1is a 154kDa cell wall anchored multimodular glycosyl hydrolase family 10 (GH10) xylanase. In this work, the 38kDa catalytic module of PbXynA1 has been structurally characterized revealing several new features not previously observed in structures of GH10 xylanases. These features are thought to facilitate hydrolysis of highly substituted, chemically complex xylans that may be the form found in close proximity to the cell wall of PbJDR2, an organism shown to have a preference for growth on polymeric glucuronoxylan.
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17
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Introducing endo-xylanase activity into an exo-acting arabinofuranosidase that targets side chains. Proc Natl Acad Sci U S A 2012; 109:6537-42. [PMID: 22492980 DOI: 10.1073/pnas.1117686109] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The degradation of the plant cell wall by glycoside hydrolases is central to environmentally sustainable industries. The major polysaccharides of the plant cell wall are cellulose and xylan, a highly decorated β-1,4-xylopyranose polymer. Glycoside hydrolases displaying multiple catalytic functions may simplify the enzymes required to degrade plant cell walls, increasing the industrial potential of these composite structures. Here we test the hypothesis that glycoside hydrolase family 43 (GH43) provides a suitable scaffold for introducing additional catalytic functions into enzymes that target complex structures in the plant cell wall. We report the crystal structure of Humicola insolens AXHd3 (HiAXHd3), a GH43 arabinofuranosidase that hydrolyses O3-linked arabinose of doubly substituted xylans, a feature of the polysaccharide that is recalcitrant to degradation. HiAXHd3 displays an N-terminal five-bladed β-propeller domain and a C-terminal β-sandwich domain. The interface between the domains comprises a xylan binding cleft that houses the active site pocket. Substrate specificity is conferred by a shallow arabinose binding pocket adjacent to the deep active site pocket, and through the orientation of the xylan backbone. Modification of the rim of the active site introduces endo-xylanase activity, whereas the resultant enzyme variant, Y166A, retains arabinofuranosidase activity. These data show that the active site of HiAXHd3 is tuned to hydrolyse arabinofuranosyl or xylosyl linkages, and it is the topology of the distal regions of the substrate binding surface that confers specificity. This report demonstrates that GH43 provides a platform for generating bespoke multifunctional enzymes that target industrially significant complex substrates, exemplified by the plant cell wall.
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18
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19
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Correia MAS, Mazumder K, Brás JLA, Firbank SJ, Zhu Y, Lewis RJ, York WS, Fontes CMGA, Gilbert HJ. Structure and function of an arabinoxylan-specific xylanase. J Biol Chem 2011; 286:22510-20. [PMID: 21378160 DOI: 10.1074/jbc.m110.217315] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The enzymatic degradation of plant cell walls plays a central role in the carbon cycle and is of increasing environmental and industrial significance. The enzymes that catalyze this process include xylanases that degrade xylan, a β-1,4-xylose polymer that is decorated with various sugars. Although xylanases efficiently hydrolyze unsubstituted xylans, these enzymes are unable to access highly decorated forms of the polysaccharide, such as arabinoxylans that contain arabinofuranose decorations. Here, we show that a Clostridium thermocellum enzyme, designated CtXyl5A, hydrolyzes arabinoxylans but does not attack unsubstituted xylans. Analysis of the reaction products generated by CtXyl5A showed that all the oligosaccharides contain an O3 arabinose linked to the reducing end xylose. The crystal structure of the catalytic module (CtGH5) of CtXyl5A, appended to a family 6 noncatalytic carbohydrate-binding module (CtCBM6), showed that CtGH5 displays a canonical (α/β)(8)-barrel fold with the substrate binding cleft running along the surface of the protein. The catalytic apparatus is housed in the center of the cleft. Adjacent to the -1 subsite is a pocket that could accommodate an l-arabinofuranose-linked α-1,3 to the active site xylose, which is likely to function as a key specificity determinant. CtCBM6, which adopts a β-sandwich fold, recognizes the termini of xylo- and gluco-configured oligosaccharides, consistent with the pocket topology displayed by the ligand-binding site. In contrast to typical modular glycoside hydrolases, there is an extensive hydrophobic interface between CtGH5 and CtCBM6, and thus the two modules cannot function as independent entities.
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Affiliation(s)
- Márcia A S Correia
- Centro de Investigação Interdisciplinar em Sanidade Animal, Faculdade de Medicina Veterinária, Universidade Técnica de Lisboa, Avenida da Universidade Técnica, 1300-477 Lisboa, Portugal
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20
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Hekmat O, Lo Leggio L, Rosengren A, Kamarauskaite J, Kolenova K, Stålbrand H. Rational Engineering of Mannosyl Binding in the Distal Glycone Subsites of Cellulomonas fimi Endo-β-1,4-mannanase: Mannosyl Binding Promoted at Subsite −2 and Demoted at Subsite −3,. Biochemistry 2010; 49:4884-96. [DOI: 10.1021/bi100097f] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Omid Hekmat
- Department of Biochemistry, Center for Chemistry and Chemical Engineering, Lund University, Box 124, SE-221 00 Lund, Sweden
| | - Leila Lo Leggio
- Biophysical Chemistry Group, Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen, Denmark
| | - Anna Rosengren
- Department of Biochemistry, Center for Chemistry and Chemical Engineering, Lund University, Box 124, SE-221 00 Lund, Sweden
| | - Jurate Kamarauskaite
- Biophysical Chemistry Group, Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen, Denmark
- Department of Biology, University of Copenhagen, Ole Maaløes Vej 5, DK-2200 Copenhagen, Denmark
| | - Katarina Kolenova
- Department of Biochemistry, Center for Chemistry and Chemical Engineering, Lund University, Box 124, SE-221 00 Lund, Sweden
| | - Henrik Stålbrand
- Department of Biochemistry, Center for Chemistry and Chemical Engineering, Lund University, Box 124, SE-221 00 Lund, Sweden
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21
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Rose DJ, Inglett GE, Liu SX. Utilisation of corn (Zea mays) bran and corn fiber in the production of food components. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2010; 90:915-924. [PMID: 20355130 DOI: 10.1002/jsfa.3915] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The milling of corn for the production of food constituents results in a number of low-value co-products. Two of the major co-products produced by this operation are corn bran and corn fiber, which currently have low commercial value. This review focuses on current and prospective research surrounding the utilization of corn fiber and corn bran in the production of potentially higher-value food components. Corn bran and corn fiber contain potentially useful components that may be harvested through physical, chemical or enzymatic means for the production of food ingredients or additives, including corn fiber oil, corn fiber gum, cellulosic fiber gels, xylo-oligosaccharides and ferulic acid. Components of corn bran and corn fiber may also be converted to food chemicals such as vanillin and xylitol. Commercialization of processes for the isolation or production of food products from corn bran or corn fiber has been met with numerous technical challenges, therefore further research that improves the production of these components from corn bran or corn fiber is needed.
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Affiliation(s)
- Devin J Rose
- Functional Foods Research Unit, National Center for Agricultural Utilization Research, USDA, ARS, 1815 N University Street, Peoria, IL 61604, USA
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22
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Pollet A, Delcour JA, Courtin CM. Structural determinants of the substrate specificities of xylanases from different glycoside hydrolase families. Crit Rev Biotechnol 2010; 30:176-91. [DOI: 10.3109/07388551003645599] [Citation(s) in RCA: 176] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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23
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Catalytic properties of a GH10 endo-β-1,4-xylanase from Streptomyces thermocarboxydus HY-15 isolated from the gut of Eisenia fetida. ACTA ACUST UNITED AC 2010. [DOI: 10.1016/j.molcatb.2009.08.015] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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24
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Tailford LE, Ducros VMA, Flint JE, Roberts SM, Morland C, Zechel DL, Smith N, Bjørnvad ME, Borchert TV, Wilson KS, Davies GJ, Gilbert HJ. Understanding how diverse beta-mannanases recognize heterogeneous substrates. Biochemistry 2009; 48:7009-18. [PMID: 19441796 DOI: 10.1021/bi900515d] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The mechanism by which polysaccharide-hydrolyzing enzymes manifest specificity toward heterogeneous substrates, in which the sequence of sugars is variable, is unclear. An excellent example of such heterogeneity is provided by the plant structural polysaccharide glucomannan, which comprises a backbone of beta-1,4-linked glucose and mannose units. beta-Mannanases, located in glycoside hydrolase (GH) families 5 and 26, hydrolyze glucomannan by cleaving the glycosidic bond of mannosides at the -1 subsite. The mechanism by which these enzymes select for glucose or mannose at distal subsites, which is critical to defining their substrate specificity on heterogeneous polymers, is currently unclear. Here we report the biochemical properties and crystal structures of both a GH5 mannanase and a GH26 mannanase and describe the contributions to substrate specificity in these enzymes. The GH5 enzyme, BaMan5A, derived from Bacillus agaradhaerens, can accommodate glucose or mannose at both its -2 and +1 subsites, while the GH26 Bacillus subtilis mannanase, BsMan26A, displays tight specificity for mannose at its negative binding sites. The crystal structure of BaMan5A reveals that a polar residue at the -2 subsite can make productive contact with the substrate 2-OH group in either its axial (as in mannose) or its equatorial (as in glucose) configuration, while other distal subsites do not exploit the 2-OH group as a specificity determinant. Thus, BaMan5A is able to hydrolyze glucomannan in which the sequence of glucose and mannose is highly variable. The crystal structure of BsMan26A in light of previous studies on the Cellvibrio japonicus GH26 mannanases CjMan26A and CjMan26C reveals that the tighter mannose recognition at the -2 subsite is mediated by polar interactions with the axial 2-OH group of a (4)C(1) ground state mannoside. Mutagenesis studies showed that variants of CjMan26A, from which these polar residues had been removed, do not distinguish between Man and Glc at the -2 subsite, while one of these residues, Arg 361, confers the elevated activity displayed by the enzyme against mannooligosaccharides. The biological rationale for the variable recognition of Man- and Glc-configured sugars by beta-mannanases is discussed.
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Affiliation(s)
- Louise E Tailford
- Institute for Cell and Molecular Biosciences, Newcastle University, The Medical School, Newcastle upon Tyne NE2 4HH, UK
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25
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Kaneko S, Ichinose H, Fujimoto Z, Iwamatsu S, Kuno A, Hasegawa T. Substrate Recognition of a Family 10 Xylanase from Streptomyces olivaceoviridis E-86: A Study by Site-directed Mutagenesis to Make an Hindrance around the Entrance toward the Substrate-binding Cleft. J Appl Glycosci (1999) 2009. [DOI: 10.5458/jag.56.173] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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26
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Zhang Y, Ju J, Peng H, Gao F, Zhou C, Zeng Y, Xue Y, Li Y, Henrissat B, Gao GF, Ma Y. Biochemical and Structural Characterization of the Intracellular Mannanase AaManA of Alicyclobacillus acidocaldarius Reveals a Novel Glycoside Hydrolase Family Belonging to Clan GH-A. J Biol Chem 2008; 283:31551-8. [DOI: 10.1074/jbc.m803409200] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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Dumon C, Varvak A, Wall MA, Flint JE, Lewis RJ, Lakey JH, Morland C, Luginbühl P, Healey S, Todaro T, DeSantis G, Sun M, Parra-Gessert L, Tan X, Weiner DP, Gilbert HJ. Engineering hyperthermostability into a GH11 xylanase is mediated by subtle changes to protein structure. J Biol Chem 2008; 283:22557-64. [PMID: 18515360 DOI: 10.1074/jbc.m800936200] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Understanding the structural basis for protein thermostability is of considerable biological and biotechnological importance as exemplified by the industrial use of xylanases at elevated temperatures in the paper pulp and animal feed sectors. Here we have used directed protein evolution to generate hyperthermostable variants of a thermophilic GH11 xylanase, EvXyn11. The Gene Site Saturation Mutagenesis (GSSM) methodology employed assesses the influence on thermostability of all possible amino acid substitutions at each position in the primary structure of the target protein. The 15 most thermostable mutants, which generally clustered in the N-terminal region of the enzyme, had melting temperatures (Tm) 1-8 degrees C higher than the parent protein. Screening of a combinatorial library of the single mutants identified a hyperthermostable variant, EvXyn11TS, containing seven mutations. EvXyn11TS had a Tm approximately 25 degrees C higher than the parent enzyme while displaying catalytic properties that were similar to EvXyn11. The crystal structures of EvXyn11 and EvXyn11TS revealed an absence of substantial changes to identifiable intramolecular interactions. The only explicable mutations are T13F, which increases hydrophobic interactions, and S9P that apparently locks the conformation of a surface loop. This report shows that the molecular basis for the increased thermostability is extraordinarily subtle and points to the requirement for new tools to interrogate protein folding at non-ambient temperatures.
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Affiliation(s)
- Claire Dumon
- Institute for Cell and Molecular Biosciences, Newcastle University, The Medical School, Newcastle Upon Tyne NE2 4HH, United Kingdom
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Factors affecting xylanase functionality in the degradation of arabinoxylans. Biotechnol Lett 2008; 30:1139-50. [DOI: 10.1007/s10529-008-9669-6] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2007] [Revised: 02/04/2008] [Accepted: 02/07/2008] [Indexed: 10/22/2022]
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Afzal AJ, Bokhari SA, Siddiqui KS. Kinetic and thermodynamic study of a chemically modified highly active xylanase fromScopulariopsis sp. Appl Biochem Biotechnol 2007; 141:273-97. [DOI: 10.1007/bf02729068] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2006] [Revised: 09/18/2006] [Accepted: 10/30/2006] [Indexed: 11/29/2022]
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St John FJ, Rice JD, Preston JF. Characterization of XynC from Bacillus subtilis subsp. subtilis strain 168 and analysis of its role in depolymerization of glucuronoxylan. J Bacteriol 2006; 188:8617-26. [PMID: 17028274 PMCID: PMC1698249 DOI: 10.1128/jb.01283-06] [Citation(s) in RCA: 96] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2006] [Accepted: 09/28/2006] [Indexed: 11/20/2022] Open
Abstract
Secretion of xylanase activities by Bacillus subtilis 168 supports the development of this well-defined genetic system for conversion of methylglucuronoxylan (MeGAXn [where n represents the number of xylose residues]) in the hemicellulose component of lignocellulosics to biobased products. In addition to the characterized glycosyl hydrolase family 11 (GH 11) endoxylanase designated XynA, B. subtilis 168 secretes a second endoxylanase as the translated product of the ynfF gene. This sequence shows remarkable homology to the GH 5 endoxylanase secreted by strains of Erwinia chrysanthemi. To determine its properties and potential role in the depolymerization of MeGAXn, the ynfF gene was cloned and overexpressed to provide an endoxylanase, designated XynC, which was characterized with respect to substrate preference, kinetic properties, and product formation. With different sources of MeGAXn as the substrate, the specific activity increased with increasing methylglucuronosyl substitutions on the beta-1,4-xylan chain. With MeGAXn from sweetgum as a preferred substrate, XynC exhibited a Vmax of 59.9 units/mg XynC, a Km of 1.63 mg MeGAXn/ml, and a k(cat) of 2,635/minute at pH 6.0 and 37 degrees C. Matrix-assisted laser desorption ionization-time of flight mass spectrometry and 1H nuclear magnetic resonance data revealed that each hydrolysis product has a single glucuronosyl substitution penultimate to the reducing terminal xylose. This detailed analysis of XynC from B. subtilis 168 defines the unique depolymerization process catalyzed by the GH 5 endoxylanases. Based upon product analysis, B. subtilis 168 secretes both XynA and XynC. Expression of xynA was subject to MeGAXn induction; xynC expression was constitutive with growth on different substrates. Translation and secretion of both GH 11 and GH 5 endoxylanases by the fully sequenced and genetically malleable B. subtilis 168 recommends this bacterium for the introduction of genes required for the complete utilization of products of the enzyme-catalyzed depolymerization of MeGAXn. B. subtilis may serve as a model platform for development of gram-positive biocatalysts for conversion of lignocellulosic materials to renewable fuels and chemicals.
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Affiliation(s)
- Franz J St John
- Department of Microbiology and Cell Science, University of Florida, Box 110700, Bldg. 981, Museum Rd., Gainesville, FL 32611, USA
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Xie H, Flint J, Vardakou M, Lakey JH, Lewis RJ, Gilbert HJ, Dumon C. Probing the structural basis for the difference in thermostability displayed by family 10 xylanases. J Mol Biol 2006; 360:157-67. [PMID: 16762367 DOI: 10.1016/j.jmb.2006.05.002] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2006] [Revised: 04/27/2006] [Accepted: 05/01/2006] [Indexed: 11/29/2022]
Abstract
Thermostability is an important property of industrially significant hydrolytic enzymes: understanding the structural basis for this attribute will underpin the future biotechnological exploitation of these biocatalysts. The Cellvibrio family 10 (GH10) xylanases display considerable sequence identity but exhibit significant differences in thermostability; thus, these enzymes represent excellent models to examine the structural basis for the variation in stability displayed by these glycoside hydrolases. Here, we have subjected the intracellular Cellvibrio mixtus xylanase CmXyn10B to forced protein evolution. Error-prone PCR and selection identified a double mutant, A334V/G348D, which confers an increase in thermostability. The mutant has a Tm 8 degrees C higher than the wild-type enzyme and, at 55 degrees C, the first-order rate constant for thermal inactivation of A334V/G348D is 4.1 x 10(-4) min(-1), compared to a value of 1.6 x 10(-1) min(-1) for the wild-type enzyme. The introduction of the N to C-terminal disulphide bridge into A334V/G348D, which increases the thermostability of wild-type CmXyn10B, conferred a further approximately 2 degrees C increase in the Tm of the double mutant. The crystal structure of A334V/G348D showed that the introduction of Val334 fills a cavity within the hydrophobic core of the xylanase, increasing the number of van der Waals interactions with the surrounding aromatic residues, while O(delta1) of Asp348 makes an additional hydrogen bond with the amide of Gly344 and O(delta2) interacts with the arabinofuranose side-chain of the xylose moiety at the -2 subsite. To investigate the importance of xylan decorations in productive substrate binding, the activity of wild-type CmXyn10B, the mutant A334V/G348D, and several other GH10 xylanases against xylotriose and xylotriose containing an arabinofuranose side-chain (AX3) was assessed. The enzymes were more active against AX3 than xylotriose, providing evidence that the arabinose side-chain makes a generic contribution to substrate recognition by GH10 xylanases.
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Affiliation(s)
- Hefang Xie
- The Department of Animal Science, Rongchang Campus, Southwest University, The People's Republic of China, 402460
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Kolenová K, Vrsanská M, Biely P. Mode of action of endo-β-1,4-xylanases of families 10 and 11 on acidic xylooligosaccharides. J Biotechnol 2006; 121:338-45. [PMID: 16157409 DOI: 10.1016/j.jbiotec.2005.08.001] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2005] [Revised: 07/22/2005] [Accepted: 08/02/2005] [Indexed: 10/25/2022]
Abstract
Mode of action of endo-beta-1,4-xylanases (EXs) of glycoside hydrolase families 10 (GH-10) and 11 (GH-11) was examined on various acidic xylooligosaccharides. As expected, none of the enzymes of GH-10 cleaved aldotetraouronic acid (MeGlcA3Xyl3), which is the shortest acidic product of the action of these EXs on glucuronoxylan. Surprisingly, aldopentaouronic acid (MeGlcA3Xyl4) was also not attacked. Only aldohexaouronic acid (MeGlcA3Xyl5) served as a substrate and was cleaved to xylobiose and aldotetraouronic acid. These results suggested that binding of xylopyranosyl residue in the -2 subsite is prerequisite for cleavage of the linkage adjacent to the xylopyranosyl unit carrying MeGlcA. EXs of family GH-11 cleaved neither aldotetraouronic acid, nor aldopentaouronic acid, which is in agreement with their action on glucuronoxylan. Aldohexaouronic acid was cleaved to aldopentaouronic acid and xylobiose without any production of xylose, suggesting that a xylosyl transfer reaction is involved in the degradation of the substrate by EXs of GH-11.
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Affiliation(s)
- Katarína Kolenová
- Slovak Academy of Sciences, Institute of Chemistry, Dúbravská cesta 9, 84538 Bratislava, Slovakia.
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Stjohn FJ, Rice JD, Preston JF. Paenibacillus sp. strain JDR-2 and XynA1: a novel system for methylglucuronoxylan utilization. Appl Environ Microbiol 2006; 72:1496-506. [PMID: 16461704 PMCID: PMC1392964 DOI: 10.1128/aem.72.2.1496-1506.2006] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2005] [Accepted: 12/01/2005] [Indexed: 11/20/2022] Open
Abstract
Environmental and economic factors predicate the need for efficient processing of renewable sources of fuels and chemicals. To fulfill this need, microbial biocatalysts must be developed to efficiently process the hemicellulose fraction of lignocellulosic biomass for fermentation of pentoses. The predominance of methylglucuronoxylan (MeGAXn), a beta-1,4 xylan in which 10% to 20% of the xylose residues are substituted with alpha-1,2-4-O-methylglucuronate residues, in hemicellulose fractions of hardwood and crop residues has made this a target for processing and fermentation. A Paenibacillus sp. (strain JDR-2) has been isolated and characterized for its ability to efficiently utilize MeGAXn. A modular xylanase (XynA1) of glycosyl hydrolase family 10 (GH 10) was identified through DNA sequence analysis that consists of a triplicate family 22 carbohydrate binding module followed by a GH 10 catalytic domain followed by a single family 9 carbohydrate binding module and concluding with C-terminal triplicate surface layer homology (SLH) domains. Immunodetection of the catalytic domain of XynA1 (XynA1 CD) indicates that the enzyme is associated with the cell wall fraction, supporting an anchoring role for the SLH modules. With MeGAXn as substrate, XynA1 CD generated xylobiose and aldotetrauronate (MeGAX3) as predominant products. The inability to detect depolymerization products in medium during exponential growth of Paenibacillus sp. strain JDR-2 on MeGAXn, as well as decreased growth rate and yield with XynA1 CD-generated xylooligosaccharides and aldouronates as substrates, indicates that XynA1 catalyzes a depolymerization process coupled to product assimilation. This depolymerization/assimilation system may be utilized for development of biocatalysts to efficiently convert MeGAXn to alternative fuels and biobased products.
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Affiliation(s)
- Franz J Stjohn
- Department of Microbiology and Cell Science, University of Florida, Gainesville, FL 32611-0700, USA
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34
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Larsson AM, Anderson L, Xu B, Muñoz IG, Usón I, Janson JC, Stålbrand H, Ståhlberg J. Three-dimensional crystal structure and enzymic characterization of beta-mannanase Man5A from blue mussel Mytilus edulis. J Mol Biol 2006; 357:1500-10. [PMID: 16487541 DOI: 10.1016/j.jmb.2006.01.044] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2005] [Revised: 01/05/2006] [Accepted: 01/09/2006] [Indexed: 11/23/2022]
Abstract
Endo-beta-1,4-d-mannanase is the key depolymerizing enzyme for beta-1,4-mannan polymers present in the cell walls of plants and some algae, as well as in some types of plant seeds. Endo-1,4-beta-mannanase from blue mussel Mytilus edulis (MeMan5A) belongs to the glycoside hydrolase (GH) family 5 enzymes. The MeMan5A structure has been determined to 1.6A resolution using the multiple-wavelength anomalous dispersion method at the selenium K edge with selenomethionyl MeMan5A expressed in the yeast Pichia pastoris. As expected for GH 5 enzymes, the structure showed a (betaalpha)(8)-barrel fold. An unusually large number of histidine side-chains are exposed on the surface, which may relate to its location within the crystalline style of the digestive tract of the mussel. Kinetic analysis of MeMan5A revealed that the enzyme requires at least six subsites for efficient hydrolysis. Mannotetraose (M4) and mannopentaose (M5) were shown to interact with subsites -3 to +1, and -3 to +2, respectively. A clear kinetic threshold was observed when going from M4 to M5, indicating that the +2 subsite provides important interaction in the hydrolysis of short oligomeric mannose substrates. The catalytic centre motif at subsite -1 found in superfamily GH clan A is, as expected, conserved in MeMan5A, but the architecture of the catalytic cleft differs significantly from other GH 5 enzyme structures. We therefore suggest that MeMan5A represents a new subfamily in GH 5.
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Affiliation(s)
- Anna M Larsson
- Department of Cell and Molecular Biology, Uppsala University, Biomedical Center, Box 596, SE-751 24 Uppsala, Sweden
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35
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Vardakou M, Flint J, Christakopoulos P, Lewis RJ, Gilbert HJ, Murray JW. A family 10 Thermoascus aurantiacus xylanase utilizes arabinose decorations of xylan as significant substrate specificity determinants. J Mol Biol 2005; 352:1060-7. [PMID: 16140328 DOI: 10.1016/j.jmb.2005.07.051] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2005] [Revised: 07/14/2005] [Accepted: 07/19/2005] [Indexed: 10/25/2022]
Abstract
Xylan, which is a key component of the plant cell wall, consists of a backbone of beta-1,4-linked xylose residues that are decorated with arabinofuranose, acetyl, 4-O-methyl d-glucuronic acid and ferulate. The backbone of xylan is hydrolysed by endo-beta1,4-xylanases (xylanases); however, it is unclear whether the various side-chains of the polysaccharide are utilized by these enzymes as significant substrate specificity determinants. To address this question we have determined the crystal structure of a family 10 xylanase from Thermoascus aurantiacus, in complex with xylobiose containing an arabinofuranosyl-ferulate side-chain. We show that the distal glycone subsite of the enzyme makes extensive direct and indirect interactions with the arabinose side-chain, while the ferulate moiety is solvent-exposed. Consistent with the 3D structural data, the xylanase displays fourfold more activity against xylotriose in which the non-reducing moiety is linked to an arabinose side-chain, compared to the undecorated form of the oligosacchairde. These data indicate that the sugar decorations of xylans in the T.aurantiacus family 10 xylanase, rather than simply being accommodated, can be significant substrate specificity determinants.
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Affiliation(s)
- Maria Vardakou
- Biotechnology Laboratory, Chemical Engineering Department, National Technical University of Athens, 5 Iroon Polytechniou Str, Zografou Campus, 15780, Athens, Greece
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36
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Nishimoto M, Kitaoka M, Fushinobu S, Hayashi K. The role of conserved arginine residue in loop 4 of glycoside hydrolase family 10 xylanases. Biosci Biotechnol Biochem 2005; 69:904-10. [PMID: 15914908 DOI: 10.1271/bbb.69.904] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
An arginine residue in loop 4 connecting beta strand 4 and alpha-helix 4 is conserved in glycoside hydrolase family 10 (GH10) xylanases. The arginine residues, Arg(204) in xylanase A from Bacillus halodurans C-125 (XynA) and Arg(196) in xylanase B from Clostridium stercorarium F9 (XynB), were replaced by glutamic acid, lysine, or glutamine residues (XynA R204E, K and Q, and XynB R196E, K and Q). The pH-k(cat)/K(m) and the pH-k(cat) relationships of these mutant enzymes were measured. The pK(e2) and pK(es2) values calculated from these curves were 8.59 and 8.29 (R204E), 8.59 and 8.10 (R204K), 8.61 and 8.19 (R204Q), 7.42 and 7.19 (R196E), 7.49 and 7.18 (R196K), and 7.86 and 7.38 (R196Q) respectively. Only the pK(es2) value of arginine derivatives was less than those of the wild types (8.49 and 9.39 [XynA] and 7.62 and 7.82 [XynB]). These results suggest that the conserved arginine residue in GH10 xylanases increases the pK(a) value of the proton donor Glu during substrate binding. The arginine residue is considered to clamp the proton donor and subsite +1 to prevent structural change during substrate binding.
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37
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Andrews SR, Taylor EJ, Pell G, Vincent F, Ducros VMA, Davies GJ, Lakey JH, Gilbert HJ. The Use of Forced Protein Evolution to Investigate and Improve Stability of Family 10 Xylanases. J Biol Chem 2004; 279:54369-79. [PMID: 15452124 DOI: 10.1074/jbc.m409044200] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Metal ions such as calcium often play a key role in protein thermostability. The inclusion of metal ions in industrial processes is, however, problematic. Thus, the evolution of enzymes that display enhanced stability, which is not reliant on divalent metals, is an important biotechnological goal. Here we have used forced protein evolution to interrogate whether the stabilizing effect of calcium in an industrially relevant enzyme can be replaced with amino acid substitutions. Our study has focused on the GH10 xylanase CjXyn10A from Cellvibrio japonicus, which contains an extended calcium binding loop that confers proteinase resistance and thermostability. Three rounds of error-prone PCR and selection identified a treble mutant, D262N/A80T/R347C, which in the absence of calcium is more thermostable than wild type CjXyn10A bound to the divalent metal. D262N influences the properties of the calcium binding site, A80T fills a cavity in the enzyme, increasing the number of hydrogen bonds and van der Waals interactions, and the R347C mutation introduces a disulfide bond that decreases the free energy of the unfolded enzyme. A derivative of CjXyn10A (CfCjXyn10A) in which the calcium binding loop has been replaced with a much shorter loop from Cellulomonas fimi CfXyn10A was also subjected to forced protein evolution to select for thermostablizing mutations. Two amino acid substitutions within the introduced loop and the A80T mutation increased the thermostability of the enzyme. This study demonstrates how forced protein evolution can be used to introduce enhanced stability into industrially relevant enzymes while removing calcium as a major stability determinant.
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Affiliation(s)
- Simon R Andrews
- Structural Biology Laboratory, Department of Chemistry, University of York, Heslington, York YO10 5YW, UK
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Dias FMV, Vincent F, Pell G, Prates JAM, Centeno MSJ, Tailford LE, Ferreira LMA, Fontes CMGA, Davies GJ, Gilbert HJ. Insights into the Molecular Determinants of Substrate Specificity in Glycoside Hydrolase Family 5 Revealed by the Crystal Structure and Kinetics of Cellvibrio mixtus Mannosidase 5A. J Biol Chem 2004; 279:25517-26. [PMID: 15014076 DOI: 10.1074/jbc.m401647200] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The enzymatic hydrolysis of the glycosidic bond is central to numerous biological processes. Glycoside hydrolases, which catalyze these reactions, are grouped into families based on primary sequence similarities. One of the largest glycoside hydrolase families is glycoside hydrolase family 5 (GH5), which contains primarily endo-acting enzymes that hydrolyze beta-mannans and beta-glucans. Here we report the cloning, characterization, and three-dimensional structure of the Cellvibrio mixtus GH5 beta-mannosidase (CmMan5A). This enzyme releases mannose from the nonreducing end of mannooligosaccharides and polysaccharides, an activity not previously observed in this enzyme family. CmMan5A contains a single glycone (-1) and two aglycone (+1 and +2) sugar-binding subsites. The -1 subsite displays absolute specificity for mannose, whereas the +1 subsite does not accommodate galactosyl side chains but will bind weakly to glucose. The +2 subsite is able to bind to decorated mannose residues. CmMan5A displays similar activity against crystalline and amorphous mannans, a property rarely attributed to glycoside hydrolases. The 1.5 A crystal structure reveals that CmMan5A adopts a (beta/alpha)(8) barrel fold, and superimposition with GH5 endo-mannanases shows that dramatic differences in the length of three loops modify the active center accessibility and thus modulate the specificity from endo to exo. The most striking and significant difference is the extended loop between strand beta8 and helix alpha8 comprising residues 378-412. This insertion forms a "double" steric barrier, formed by two short beta-strands that function to "block" the substrate binding cleft at the edge of the -1 subsite forming the "exo" active center topology of CmMan5A.
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Affiliation(s)
- Fernando M V Dias
- CIISA-Faculdade de Medicina Veterinária, Universidade Técnica de Lisboa, Rua Prof. Cid dos Santos, 1300-477 Lisboa, Portugal
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Kaneko S, Ichinose H, Fujimoto Z, Kuno A, Yura K, Go M, Mizuno H, Kusakabe I, Kobayashi H. Structure and function of a family 10 beta-xylanase chimera of Streptomyces olivaceoviridis E-86 FXYN and Cellulomonas fimi Cex. J Biol Chem 2004; 279:26619-26. [PMID: 15078885 DOI: 10.1074/jbc.m308899200] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The catalytic domain of xylanases belonging to glycoside hydrolase family 10 (GH10) can be divided into 22 modules (M1 to M22; Sato, Y., Niimura, Y., Yura, K., and Go, M. (1999) Gene (Amst.) 238, 93-101). Inspection of the crystal structure of a GH10 xylanase from Streptomyces olivaceoviridis E-86 (SoXyn10A) revealed that the catalytic domain of GH10 xylanases can be dissected into two parts, an N-terminal larger region and C-terminal smaller region, by the substrate binding cleft, corresponding to the module border between M14 and M15. It has been suggested that the topology of the substrate binding clefts of GH10 xylanases are not conserved (Charnock, S. J., Spurway, T. D., Xie, H., Beylot, M. H., Virden, R., Warren, R. A. J., Hazlewood, G. P., and Gilbert, H. J. (1998) J. Biol. Chem. 273, 32187-32199). To facilitate a greater understanding of the structure-function relationship of the substrate binding cleft of GH10 xylanases, a chimeric xylanase between SoXyn10A and Xyn10A from Cellulomonas fimi (CfXyn10A) was constructed, and the topology of the hybrid substrate binding cleft established. At the three-dimensional level, SoXyn10A and CfXyn10A appear to possess 5 subsites, with the amino acid residues comprising subsites -3 to +1 being well conserved, although the +2 subsites are quite different. Biochemical analyses of the chimeric enzyme along with SoXyn10A and CfXyn10A indicated that differences in the structure of subsite +2 influence bond cleavage frequencies and the catalytic efficiency of xylooligosaccharide hydrolysis. The hybrid enzyme constructed in this study displays fascinating biochemistry, with an interesting combination of properties from the parent enzymes, resulting in a low production of xylose.
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Affiliation(s)
- Satoshi Kaneko
- National Food Research Institute, 2-1-12 Kannondai, Tsukuba, Ibaraki 305-8642, Japan.
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40
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Pell G, Szabo L, Charnock SJ, Xie H, Gloster TM, Davies GJ, Gilbert HJ. Structural and biochemical analysis of Cellvibrio japonicus xylanase 10C: how variation in substrate-binding cleft influences the catalytic profile of family GH-10 xylanases. J Biol Chem 2003; 279:11777-88. [PMID: 14670951 DOI: 10.1074/jbc.m311947200] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Microbial degradation of the plant cell wall is the primary mechanism by which carbon is utilized in the biosphere. The hydrolysis of xylan, by endo-beta-1,4-xylanases (xylanases), is one of the key reactions in this process. Although amino acid sequence variations are evident in the substrate binding cleft of "family GH10" xylanases (see afmb.cnrs-mrs.fr/CAZY/), their biochemical significance is unclear. The Cellvibrio japonicus GH10 xylanase CjXyn10C is a bi-modular enzyme comprising a GH10 catalytic module and a family 15 carbohydrate-binding module. The three-dimensional structure at 1.85 A, presented here, shows that the sequence joining the two modules is disordered, confirming that linker sequences in modular glycoside hydrolases are highly flexible. CjXyn10C hydrolyzes xylan at a rate similar to other previously described GH10 enzymes but displays very low activity against xylooligosaccharides. The poor activity on short substrates reflects weak binding at the -2 subsite of the enzyme. Comparison of CjXyn10C with other family GH10 enzymes reveals "polymorphisms" in the substrate binding cleft including a glutamate/glycine substitution at the -2 subsite and a tyrosine insertion in the -2/-3 glycone region of the substrate binding cleft, both of which contribute to the unusual properties of the enzyme. The CjXyn10C-substrate complex shows that Tyr-340 stacks against the xylose residue located at the -3 subsite, and the properties of Y340A support the view that this tyrosine plays a pivotal role in substrate binding at this location. The generic importance of using CjXyn10C as a template in predicting the biochemical properties of GH10 xylanases is discussed.
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Affiliation(s)
- Gavin Pell
- School of Cell and Molecular Biosciences, University of Newcastle upon Tyne, The Agriculture Bldg., Newcastle upon Tyne NE1 7RU
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41
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Pell G, Taylor EJ, Gloster TM, Turkenburg JP, Fontes CMGA, Ferreira LMA, Nagy T, Clark SJ, Davies GJ, Gilbert HJ. The mechanisms by which family 10 glycoside hydrolases bind decorated substrates. J Biol Chem 2003; 279:9597-605. [PMID: 14668328 DOI: 10.1074/jbc.m312278200] [Citation(s) in RCA: 137] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Endo-beta-1,4-xylanases (xylanases), which cleave beta-1,4 glycosidic bonds in the xylan backbone, are important components of the repertoire of enzymes that catalyze plant cell wall degradation. The mechanism by which these enzymes are able to hydrolyze a range of decorated xylans remains unclear. Here we reveal the three-dimensional structure, determined by x-ray crystallography, and the catalytic properties of the Cellvibrio mixtus enzyme Xyn10B (CmXyn10B), the most active GH10 xylanase described to date. The crystal structure of the enzyme in complex with xylopentaose reveals that at the +1 subsite the xylose moiety is sandwiched between hydrophobic residues, which is likely to mediate tighter binding than in other GH10 xylanases. The crystal structure of the xylanase in complex with a range of decorated xylooligosaccharides reveals how this enzyme is able to hydrolyze substituted xylan. Solvent exposure of the O-2 groups of xylose at the +4, +3, +1, and -3 subsites may allow accommodation of the alpha-1,2-linked 4-O-methyl-d-glucuronic acid side chain in glucuronoxylan at these locations. Furthermore, the uronic acid makes hydrogen bonds and hydrophobic interactions with the enzyme at the +1 subsite, indicating that the sugar decorations in glucuronoxylan are targeted to this proximal aglycone binding site. Accommodation of 3'-linked l-arabinofuranoside decorations is observed in the -2 subsite and could, most likely, be tolerated when bound to xylosides in -3 and +4. A notable feature of the binding mode of decorated substrates is the way in which the subsite specificities are tailored both to prevent the formation of "dead-end" reaction products and to facilitate synergy with the xylan degradation-accessory enzymes such as alpha-glucuronidase. The data described in this report and in the accompanying paper indicate that the complementarity in the binding of decorated substrates between the glycone and aglycone regions appears to be a conserved feature of GH10 xylanases.
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Affiliation(s)
- Gavin Pell
- School of Cell and Molecular Biosciences, University of Newcastle upon Tyne, Agriculture Building, Newcastle upon Tyne NE1 7RU, United Kingdom
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42
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Pell G, Williamson MP, Walters C, Du H, Gilbert HJ, Bolam DN. Importance of hydrophobic and polar residues in ligand binding in the family 15 carbohydrate-binding module from Cellvibrio japonicus Xyn10C. Biochemistry 2003; 42:9316-23. [PMID: 12899618 DOI: 10.1021/bi0347510] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Modular glycoside hydrolases that degrade the plant cell wall often contain noncatalytic carbohydrate-binding modules (CBMs) that interact with specific polysaccharides within this complex macromolecule. CBMs, by bringing the appended catalytic module into intimate and prolonged association with the substrate, increase the rate at which these enzymes are able to hydrolyze glycosidic bonds. Recently, the crystal structure of the family 15 CBM (CBM15) from Cellvibrio japonicus (formerly Pseudomonas cellulosa) Xyn10C was determined in complex with the ligand xylopentaose. In this report we have used a rational design approach, informed by the crystal structure of the CBM15-ligand complex, to probe the importance of hydrophobic stacking interactions and both direct and water-mediated hydrogen bonds in the binding of this protein to xylan and xylohexaose. The data show that replacing either Trp 171 or Trp 186, which stack against xylose residues n and n + 2 in xylopentaose, with alanine abolished ligand binding. Similarly, replacing Asn 106, Gln 171, and Gln 217, which make direct hydrogen bonds with xylopentaose, with alanine greatly reduced the affinity of the protein for its saccharide ligands. By contrast, disrupting water-mediated hydrogen bonds between CBM15 and xylopentaose by introducing the mutations S108A, Q167A, Q221A, and K223A had little effect on the affinity of the protein for xylan or xylohexaose. These data indicate that CBM15 binds xylan and xylooligosaccharides via the same interactions and provide clear evidence that direct hydrogen bonds are a key determinant of affinity in a type B CBM. The generic importance of these data is discussed.
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Affiliation(s)
- Gavin Pell
- School of Cell and Molecular Biosciences, University of Newcastle upon Tyne, Newcastle upon Tyne NE1 7RU, United Kingdom
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43
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Nagy T, Nurizzo D, Davies GJ, Biely P, Lakey JH, Bolam DN, Gilbert HJ. The alpha-glucuronidase, GlcA67A, of Cellvibrio japonicus utilizes the carboxylate and methyl groups of aldobiouronic acid as important substrate recognition determinants. J Biol Chem 2003; 278:20286-92. [PMID: 12654910 DOI: 10.1074/jbc.m302205200] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
alpha-Glucuronidases are key components of the ensemble of enzymes that degrade the plant cell wall. They hydrolyze the alpha1,2-glycosidic bond between 4-O-methyl-d-glucuronic acid (4-O-MeGlcA) and the xylan or xylooligosaccharide backbone. Here we report the crystal structure of an inactive mutant (E292A) of the alpha-glucuronidase, GlcA67A, from Cellvibrio japonicus in complex with its substrate. The data show that the 4-O-methyl group of the substrate is accommodated within a hydrophobic sheath flanked by Val-210 and Trp-160, whereas the carboxylate moiety is located within a positively charged region of the substrate-binding pocket. The carboxylate side chains of Glu-393 and Asp-365, on the "beta-face" of 4-O-MeGlcA, form hydrogen bonds with a water molecule that is perfectly positioned to mount a nucleophilic attack at the anomeric carbon of the target glycosidic bond, providing further support for the view that, singly or together, these amino acids function as the catalytic base. The capacity of reaction products and product analogues to inhibit GlcA67A shows that the 4-O-methyl group, the carboxylate, and the xylose sugar of aldobiouronic acid all play an important role in substrate binding. Site-directed mutagenesis informed by the crystal structure of enzyme-ligand complexes was used to probe the importance of highly conserved residues at the active site of GlcA67A. The biochemical properties of K288A, R325A, and K360A show that a constellation of three basic amino acids (Lys-288, Arg-325, and Lys-360) plays a critical role in binding the carboxylate moiety of 4-O-MeGlcA. Disruption of the apolar nature of the pocket created by Val-210 (V210N and V210S) has a detrimental effect on substrate binding, although the reduction in affinity is not reflected by an inability to accommodate the 4-O-methyl group. Replacing the two tryptophan residues that stack against the sugar rings of the substrate with alanine (W160A and W543A) greatly reduced activity.
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Affiliation(s)
- Tibor Nagy
- School of Cell and Molecular Biosciences, The University of Newcastle upon Tyne, United Kingdom
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44
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Ryttersgaard C, Lo Leggio L, Coutinho PM, Henrissat B, Larsen S. Aspergillus aculeatus beta-1,4-galactanase: substrate recognition and relations to other glycoside hydrolases in clan GH-A. Biochemistry 2002; 41:15135-43. [PMID: 12484750 DOI: 10.1021/bi026238c] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The three-dimensional structure of Aspergillus aculeatus beta-1,4-galactanase (AAGAL), an enzyme involved in pectin degradation, has been determined by multiple isomorphous replacement to 2.3 and 1.8 A resolution at 293 and 100 K, respectively. It represents the first known structure for a polysaccharidase with this specificity and for a member of glycoside hydrolase family 53 (GH-53). The enzyme folds into a (beta/alpha)(8) barrel with the active site cleft located at the C-terminal side of the barrel consistent with the classification of GH-53 in clan GH-A, a superfamily of enzymes with common fold and catalytic machinery but diverse specificities. Putative substrate-enzyme interactions were elucidated by modeling of beta-1,4-linked galactobioses into the possible substrate binding subsites. The structure and modeling studies identified five potential subsites for the binding of galactans, of which one is a pocket suited for accommodating the arabinan side chain in arabinogalactan, one of the natural substrates. A comparison with the substrate binding grooves of other Clan GH-A enzymes suggests that shape complementarity is crucial in determining the specificity of polysaccharidases.
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Affiliation(s)
- Carsten Ryttersgaard
- Centre for Crystallographic Studies, Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen, Denmark
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45
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Charnock SJ, Brown IE, Turkenburg JP, Black GW, Davies GJ. Convergent evolution sheds light on the anti-beta -elimination mechanism common to family 1 and 10 polysaccharide lyases. Proc Natl Acad Sci U S A 2002; 99:12067-72. [PMID: 12221284 PMCID: PMC129399 DOI: 10.1073/pnas.182431199] [Citation(s) in RCA: 78] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2002] [Accepted: 07/19/2002] [Indexed: 11/18/2022] Open
Abstract
Enzyme-catalyzed beta-elimination of sugar uronic acids, exemplified by the degradation of plant cell wall pectins, plays an important role in a wide spectrum of biological processes ranging from the recycling of plant biomass through to pathogen virulence. The three-dimensional crystal structure of the catalytic module of a "family PL-10" polysaccharide lyase, Pel10Acm from Cellvibrio japonicus, solved at a resolution of 1.3 A, reveals a new polysaccharide lyase fold and is the first example of a polygalacturonic acid lyase that does not exhibit the "parallel beta-helix" topology. The "Michaelis" complex of an inactive mutant in association with the substrate trigalacturonate/Ca2+ reveals the catalytic machinery harnessed by this polygalacturonate lyase, which displays a stunning resemblance, presumably through convergent evolution, to the tetragalacturonic acid complex observed for a structurally unrelated polygalacturonate lyase from family PL-1. Common coordination of the -1 and +1 subsite saccharide carboxylate groups by a protein-liganded Ca2+ ion, the positioning of an arginine catalytic base in close proximity to the alpha-carbon hydrogen and numerous other conserved enzyme-substrate interactions, considered in light of mutagenesis data for both families, suggest a generic polysaccharide anti-beta-elimination mechanism.
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Affiliation(s)
- Simon J Charnock
- York Structural Biology Laboratory, Department of Chemistry, University of York, Heslington, York YO10 5YW, United Kingdom
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46
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Nurizzo D, Nagy T, Gilbert HJ, Davies GJ. The structural basis for catalysis and specificity of the Pseudomonas cellulosa alpha-glucuronidase, GlcA67A. Structure 2002; 10:547-56. [PMID: 11937059 DOI: 10.1016/s0969-2126(02)00742-6] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Alpha-glucuronidases, components of an ensemble of enzymes central to the recycling of photosynthetic biomass, remove the alpha-1,2 linked 4-O-methyl glucuronic acid from xylans. The structure of the alpha-glucuronidase, GlcA67A, from Pseudomonas cellulosa reveals three domains, the central of which is a (beta/alpha)(8) barrel housing the catalytic apparatus. Complexes of the enzyme with the individual reaction products, either xylobiose or glucuronic acid, and the ternary complex of both glucuronic acid and xylotriose reveal a "blind" pocket which selects for short decorated xylooligosaccharides substituted with the uronic acid at their nonreducing end, consistent with kinetic data. The catalytic center reveals a constellation of carboxylates; Glu292 is poised to provide protonic assistance to leaving group departure with Glu393 and Asp365 both appropriately positioned to provide base-catalyzed assistance for inverting nucleophilic attack by water.
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Affiliation(s)
- Didier Nurizzo
- Structural Biology Laboratory, Department of Chemistry, The University of York, Heslington, United Kingdom
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47
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Lo Leggio L, Kalogiannis S, Eckert K, Teixeira SC, Bhat MK, Andrei C, Pickersgill RW, Larsen S. Substrate specificity and subsite mobility in T. aurantiacus xylanase 10A. FEBS Lett 2001; 509:303-8. [PMID: 11741607 DOI: 10.1016/s0014-5793(01)03177-5] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The substrate specificity of Thermoascus aurantiacus xylanase 10A (TAX) has been investigated both biochemically and structurally. High resolution crystallographic analyses at 291 K and 100 K of TAX complexes with xylobiose show that the ligand is in its alpha anomeric conformation and provide a rationale for specificity on p-nitrophenyl glycosides at the -1 and -2 subsites. Trp 275, which is disordered in uncomplexed structures, is stabilised by its interaction with xylobiose. Two structural subsets in family 10 are identified, which differ by the presence or absence of a short helical stretch in the eighth betaalpha-loop of the TIM barrel, the loop bearing Trp 275. This structural difference is discussed in the context of Trp 275 mobility and xylanase function.
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Affiliation(s)
- L Lo Leggio
- Centre for Crystallographic Studies, Chemical Institute, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen, Denmark.
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48
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Beylot MH, McKie VA, Voragen AG, Doeswijk-Voragen CH, Gilbert HJ. The Pseudomonas cellulosa glycoside hydrolase family 51 arabinofuranosidase exhibits wide substrate specificity. Biochem J 2001; 358:607-14. [PMID: 11535122 PMCID: PMC1222095 DOI: 10.1042/0264-6021:3580607] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
To investigate the mechanism by which Pseudomonas cellulosa releases arabinose from polysaccharides and oligosaccharides, a gene library of P. cellulosa genomic DNA was screened for 4-methylumbelliferyl-alpha-L-arabinofuranosidase (MUAase) activity. A single MUAase gene (abf51A) was isolated, which encoded a non-modular glycoside hydrolase family (GH) 51 arabinofuranosidase (Abf51A) of 57000 Da. The substrate specificity of the Abf51A showed that it preferentially removed alpha1,2- and alpha1,3-linked arabinofuranose side chains from either arabinan or arabinoxylan, and hydrolysed alpha1,5-linked arabino-oligosaccharides, although at a much lower rate. The activity of Abf51A against arabinoxylan was similar to a GH62 arabinofuranosidase encoded by a P. cellulosa gene. Glu-194 and Glu-321 of Abf51A are conserved in GH51 enzymes, and it has been suggested that these amino acids comprise the key catalytic acid/base and nucleophile residues, respectively. To evaluate this hypothesis the biochemical properties of E194A and E321A mutants of Abf51A were evaluated. The data were consistent with the view that Glu-194 and Glu-321 comprise the key catalytic residues of Abf51A. These data, in conjunction with the results presented in the accompanying paper [Beylot, Emami, McKie, Gilbert and Pell (2001) Biochem. J. 358, 599-605], indicate that P. cellulosa expresses a membrane-bound GH51 arabinofuranosidase that plays a pivotal role in releasing arabinose from a range of polysaccharides and oligosaccharides.
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Affiliation(s)
- M H Beylot
- Department of Biological and Nutritional Sciences, University of Newcastle upon Tyne, Newcastle upon Tyne NE1 7RU, UK
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49
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Hogg D, Woo EJ, Bolam DN, McKie VA, Gilbert HJ, Pickersgill RW. Crystal structure of mannanase 26A from Pseudomonas cellulosa and analysis of residues involved in substrate binding. J Biol Chem 2001; 276:31186-92. [PMID: 11382747 DOI: 10.1074/jbc.m010290200] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The crystal structure of Pseudomonas cellulosa mannanase 26A has been solved by multiple isomorphous replacement and refined at 1.85 A resolution to an R-factor of 0.182 (R-free = 0.211). The enzyme comprises (beta/alpha)(8)-barrel architecture with two catalytic glutamates at the ends of beta-strands 4 and 7 in precisely the same location as the corresponding glutamates in other 4/7-superfamily glycoside hydrolase enzymes (clan GH-A glycoside hydrolases). The family 26 glycoside hydrolases are therefore members of clan GH-A. Functional analyses of mannanase 26A, informed by the crystal structure of the enzyme, provided important insights into the role of residues close to the catalytic glutamates. These data showed that Trp-360 played a critical role in binding substrate at the -1 subsite, whereas Tyr-285 was important to the function of the nucleophile catalyst. His-211 in mannanase 26A does not have the same function as the equivalent asparagine in the other GH-A enzymes. The data also suggest that Trp-217 and Trp-162 are important for the activity of mannanase 26A against mannooligosaccharides but are less important for activity against polysaccharides.
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Affiliation(s)
- D Hogg
- Department of Biological and Nutritional Sciences, University of Newcastle, Newcastle upon Tyne NE1 7RU, United Kingdom
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50
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George SP, Ahmad A, Rao MB. Involvement of a lysine residue in the active site of a thermostable xylanase from Thermomonospora sp. Biochem Biophys Res Commun 2001; 282:48-54. [PMID: 11263969 DOI: 10.1006/bbrc.2001.4543] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A highly thermostable xylanase (Xyl I) produced by Thermomonospora sp. was purified to homogeneity and was classified as a family 10 xylanase based on its molecular weight (38,000 Da) and isoelectric point (4.1). K2d analysis showed that the secondary structure of Xyl I was made up of 38% alpha-helix and 10% beta-sheet. The optimal temperature for the activity of Xyl I was 80 degrees C. Xyl I was highly thermostable with half-lives of 86, 30, and 15 min at 80, 90, and 100 degrees C respectively. Xyl I was stable in an expansive pH range of 5 to 10 with more than 75% residual activity. Our present investigation using o-phthalaldehyde (OPTA) as the chemical initiator for fluorescent chemoaffinity labeling and trinitrobenzenesulphonic acid (TNBS) as chemical modifier have revealed the presence of a single lysine residue in the active site of Xyl I. The high pK value for the basic limb of the pH profile reflects the ionization of a lysine residue. The higher K(m) values and similar k(cat) values of the TNBS modified enzyme in comparison to native enzyme and the substrate protection against OPTA and TNBS, suggested the presence of the lysine residue in the substrate-binding site.
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Affiliation(s)
- S P George
- Division of Biochemical Sciences, Pune, 411 008, India
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