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Vacilotto MM, de Araujo Montalvão L, Pellegrini VDOA, Liberato MV, de Araujo EA, Polikarpov I. Two-domain GH30 xylanase from human gut microbiota as a tool for enzymatic production of xylooligosaccharides: Crystallographic structure and a synergy with GH11 xylosidase. Carbohydr Polym 2024; 337:122141. [PMID: 38710568 DOI: 10.1016/j.carbpol.2024.122141] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2023] [Revised: 03/21/2024] [Accepted: 04/07/2024] [Indexed: 05/08/2024]
Abstract
Production of value-added compounds and sustainable materials from agro-industrial residues is essential for better waste management and building of circular economy. This includes valorization of hemicellulosic fraction of plant biomass, the second most abundant biopolymer from plant cell walls, aiming to produce prebiotic oligosaccharides, widely explored in food and feed industries. In this work, we conducted biochemical and biophysical characterization of a prokaryotic two-domain R. champanellensis xylanase from glycoside hydrolase (GH) family 30 (RcXyn30A), and evaluated its applicability for XOS production from glucuronoxylan in combination with two endo-xylanases from GH10 and GH11 families and a GH11 xylobiohydrolase. RcXyn30A liberates mainly long monoglucuronylated xylooligosaccharides and is inefficient in cleaving unbranched oligosaccharides. Crystallographic structure of RcXyn30A catalytic domain was solved and refined to 1.37 Å resolution. Structural analysis of the catalytic domain releveled that its high affinity for glucuronic acid substituted xylan is due to the coordination of the substrate decoration by several hydrogen bonds and ionic interactions in the subsite -2. Furthermore, the protein has a larger β5-α5 loop as compared to other GH30 xylanases, which might be crucial for creating an additional aglycone subsite (+3) of the catalytic site. Finally, RcXyn30A activity is synergic to that of GH11 xylobiohydrolase.
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Affiliation(s)
- Milena Moreira Vacilotto
- Instituto de Física de São Carlos, Universidade de São Paulo, Avenida Trabalhador São-carlense 400, 13566-590 São Carlos, SP, Brazil
| | - Lucas de Araujo Montalvão
- Instituto de Física de São Carlos, Universidade de São Paulo, Avenida Trabalhador São-carlense 400, 13566-590 São Carlos, SP, Brazil
| | | | - Marcelo Vizona Liberato
- Instituto de Física de São Carlos, Universidade de São Paulo, Avenida Trabalhador São-carlense 400, 13566-590 São Carlos, SP, Brazil
| | - Evandro Ares de Araujo
- Centro Nacional de Pesquisa em Energia e Materiais, Giuseppe Máximo Scolfaro 10000, 13083-100 Campinas, SP, Brazil
| | - Igor Polikarpov
- Instituto de Física de São Carlos, Universidade de São Paulo, Avenida Trabalhador São-carlense 400, 13566-590 São Carlos, SP, Brazil.
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2
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Pentari C, Kosinas C, Nikolaivits E, Dimarogona M, Topakas E. Structural and molecular insights into a bifunctional glycoside hydrolase 30 xylanase specific to glucuronoxylan. Biotechnol Bioeng 2024; 121:2067-2078. [PMID: 38678481 DOI: 10.1002/bit.28731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2024] [Revised: 04/15/2024] [Accepted: 04/19/2024] [Indexed: 05/01/2024]
Abstract
Glycoside hydrolase (GH) 30 family xylanases are enzymes of biotechnological interest due to their capacity to degrade recalcitrant hemicelluloses, such as glucuronoxylan (GX). This study focuses on a subfamily 7 GH30, TtXyn30A from Thermothelomyces thermophilus, which acts on GX in an "endo" and "exo" mode, releasing methyl-glucuronic acid branched xylooligosaccharides (XOs) and xylobiose, respectively. The crystal structure of inactive TtXyn30A in complex with 23-(4-O-methyl-α-D-glucuronosyl)-xylotriose (UXX), along with biochemical analyses, corroborate the implication of E233, previously identified as alternative catalytic residue, in the hydrolysis of decorated xylan. At the -1 subsite, the xylose adopts a distorted conformation, indicative of the Michaelis complex of TtXyn30AEE with UXX trapped in the semi-functional active site. The most significant structural rearrangements upon substrate binding are observed at residues W127 and E233. The structures with neutral XOs, representing the "exo" function, clearly show the nonspecific binding at aglycon subsites, contrary to glycon sites, where the xylose molecules are accommodated via multiple interactions. Last, an unproductive ligand binding site is found at the interface between the catalytic and the secondary β-domain which is present in all GH30 enzymes. These findings improve current understanding of the mechanism of bifunctional GH30s, with potential applications in the field of enzyme engineering.
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Affiliation(s)
- Christina Pentari
- Industrial Biotechnology & Biocatalysis Group, Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens, Athens, Greece
| | - Christos Kosinas
- Laboratory of Structural Biology and Biotechnology, Department of Chemical Engineering, University of Patras, Patras, Greece
| | - Efstratios Nikolaivits
- Industrial Biotechnology & Biocatalysis Group, Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens, Athens, Greece
| | - Maria Dimarogona
- Laboratory of Structural Biology and Biotechnology, Department of Chemical Engineering, University of Patras, Patras, Greece
| | - Evangelos Topakas
- Industrial Biotechnology & Biocatalysis Group, Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens, Athens, Greece
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3
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Nakamichi Y, Watanabe M, Fujii T, Inoue H, Morita T. Crystal structure of reducing-end xylose-releasing exoxylanase in subfamily 7 of glycoside hydrolase family 30. Proteins 2023; 91:1341-1350. [PMID: 37144255 DOI: 10.1002/prot.26505] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 04/11/2023] [Accepted: 04/19/2023] [Indexed: 05/06/2023]
Abstract
TcXyn30A from Talaromyces cellulolyticus, which belongs to subfamily 7 of the glycoside hydrolase family 30 (GH30-7), releases xylose from the reducing end of xylan and xylooligosaccharides (XOSs), the so-called reducing-end xylose-releasing exoxylanase (ReX). In this study, the crystal structures of TcXyn30A with and without xylose at subsite +1 (the binding site of the xylose residue at the reducing end) were determined. This is the first report on the structure of ReX in the family GH30-7. TcXyn30A forms a dimer. The complex structure of TcXyn30A with xylose revealed that subsite +1 is located at the dimer interface. TcXyn30A recognizes xylose at subsite +1 composed of amino acid residues from each monomer and blocks substrate binding to subsite +2 by dimer formation. Thus, the dimeric conformation is responsible for ReX activity. The structural comparison between TcXyn30A and the homologous enzyme indicated that subsite -2 is composed of assembled three stacked Trp residues, Trp49, Trp333, and Trp334, allowing TcXyn30A to accommodate xylan and any branched XOSs decorated with a substitution such as α-1,2-linked 4-O-methyl-d-glucuronic acid or α-1,2- and/or -1,3-linked L-arabinofuranose. These findings provide an insight into the structural determinants for ReX activity of TcXyn30A.
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Affiliation(s)
- Yusuke Nakamichi
- Research Institute for Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), Higashi-Hiroshima, Hiroshima, Japan
| | - Masahiro Watanabe
- Research Institute for Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), Higashi-Hiroshima, Hiroshima, Japan
| | - Tatsuya Fujii
- Research Institute for Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), Higashi-Hiroshima, Hiroshima, Japan
| | - Hiroyuki Inoue
- Research Institute for Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), Higashi-Hiroshima, Hiroshima, Japan
| | - Tomotake Morita
- Research Institute for Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), Higashi-Hiroshima, Hiroshima, Japan
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Derba-Maceluch M, Sivan P, Donev EN, Gandla ML, Yassin Z, Vaasan R, Heinonen E, Andersson S, Amini F, Scheepers G, Johansson U, Vilaplana FJ, Albrectsen BR, Hertzberg M, Jönsson LJ, Mellerowicz EJ. Impact of xylan on field productivity and wood saccharification properties in aspen. FRONTIERS IN PLANT SCIENCE 2023; 14:1218302. [PMID: 37528966 PMCID: PMC10389764 DOI: 10.3389/fpls.2023.1218302] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/06/2023] [Accepted: 06/27/2023] [Indexed: 08/03/2023]
Abstract
Xylan that comprises roughly 25% of hardwood biomass is undesirable in biorefinery applications involving saccharification and fermentation. Efforts to reduce xylan levels have therefore been made in many species, usually resulting in improved saccharification. However, such modified plants have not yet been tested under field conditions. Here we evaluate the field performance of transgenic hybrid aspen lines with reduced xylan levels and assess their usefulness as short-rotation feedstocks for biorefineries. Three types of transgenic lines were tested in four-year field tests with RNAi constructs targeting either Populus GT43 clades B and C (GT43BC) corresponding to Arabidopsis clades IRX9 and IRX14, respectively, involved in xylan backbone biosynthesis, GATL1.1 corresponding to AtGALT1 involved in xylan reducing end sequence biosynthesis, or ASPR1 encoding an atypical aspartate protease. Their productivity, wood quality traits, and saccharification efficiency were analyzed. The only lines differing significantly from the wild type with respect to growth and biotic stress resistance were the ASPR1 lines, whose stems were roughly 10% shorter and narrower and leaves showed increased arthropod damage. GT43BC lines exhibited no growth advantage in the field despite their superior growth in greenhouse experiments. Wood from the ASPR1 and GT43BC lines had slightly reduced density due to thinner cell walls and, in the case of ASPR1, larger cell diameters. The xylan was less extractable by alkali but more hydrolysable by acid, had increased glucuronosylation, and its content was reduced in all three types of transgenic lines. The hemicellulose size distribution in the GALT1.1 and ASPR1 lines was skewed towards higher molecular mass compared to the wild type. These results provide experimental evidence that GATL1.1 functions in xylan biosynthesis and suggest that ASPR1 may regulate this process. In saccharification without pretreatment, lines of all three constructs provided 8-11% higher average glucose yields than wild-type plants. In saccharification with acid pretreatment, the GT43BC construct provided a 10% yield increase on average. The best transgenic lines of each construct are thus predicted to modestly outperform the wild type in terms of glucose yields per hectare. The field evaluation of transgenic xylan-reduced aspen represents an important step towards more productive feedstocks for biorefineries.
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Affiliation(s)
- Marta Derba-Maceluch
- Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Umeå, Sweden
| | - Pramod Sivan
- Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Umeå, Sweden
- Division of Glycoscience, Department of Chemistry, KTH Royal Institute of Technology, AlbaNova University Centre, Stockholm, Sweden
| | - Evgeniy N. Donev
- Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Umeå, Sweden
| | | | - Zakiya Yassin
- Enhet Produktionssystem och Material, RISE Research Institutes of Sweden, Växjö, Sweden
| | - Rakhesh Vaasan
- Division of Glycoscience, Department of Chemistry, KTH Royal Institute of Technology, AlbaNova University Centre, Stockholm, Sweden
| | - Emilia Heinonen
- Division of Glycoscience, Department of Chemistry, KTH Royal Institute of Technology, AlbaNova University Centre, Stockholm, Sweden
- Wallenberg Wood Science Centre (WWSC), KTH Royal Institute of Technology, Stockholm, Sweden
| | - Sanna Andersson
- Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Umeå, Sweden
| | - Fariba Amini
- Umeå Plant Science Centre, Department of Plant Physiology, Umeå University, Umea, Sweden
- Biology Department, Faculty of Science, Arak University, Arak, Iran
| | - Gerhard Scheepers
- Enhet Produktionssystem och Material, RISE Research Institutes of Sweden, Växjö, Sweden
| | - Ulf Johansson
- Tönnersjöheden Experimental Forest, Swedish University of Agricultural Sciences, Simlångsdalen, Sweden
| | - Francisco J. Vilaplana
- Division of Glycoscience, Department of Chemistry, KTH Royal Institute of Technology, AlbaNova University Centre, Stockholm, Sweden
- Wallenberg Wood Science Centre (WWSC), KTH Royal Institute of Technology, Stockholm, Sweden
| | | | | | | | - Ewa J. Mellerowicz
- Umeå Plant Science Centre, Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Umeå, Sweden
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Mendonça M, Barroca M, Collins T. Endo-1,4-β-xylanase-containing glycoside hydrolase families: Characteristics, singularities and similarities. Biotechnol Adv 2023; 65:108148. [PMID: 37030552 DOI: 10.1016/j.biotechadv.2023.108148] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 04/02/2023] [Accepted: 04/04/2023] [Indexed: 04/09/2023]
Abstract
Endo-1,4-β-xylanases (EC 3.2.1.8) are O-glycoside hydrolases that cleave the internal β-1,4-D-xylosidic linkages of the complex plant polysaccharide xylan. They are produced by a vast array of organisms where they play critical roles in xylan saccharification and plant cell wall hydrolysis. They are also important industrial biocatalysts with widespread application. A large and ever growing number of xylanases with wildly different properties and functionalites are known and a better understanding of these would enable a more effective use in various applications. The Carbohydrate-Active enZYmes database (CAZy), which classifies evolutionarily related proteins into a glycoside hydrolase family-subfamily organisational scheme has proven powerful in understanding these enzymes. Nevertheless, ambiguity currently exists as to the number of glycoside hydrolase families and subfamilies harbouring catalytic domains with true endoxylanase activity and as to the specific characteristics of each of these families/subfamilies. This review seeks to clarify this, identifying 9 glycoside hydrolase families containing enzymes with endo-1,4-β-xylanase activity and discussing their properties, similarities, differences and biotechnological perspectives. In particular, substrate specificities and hydrolysis patterns and the structural determinants of these are detailed, with taxonomic aspects of source organisms being also presented. Shortcomings in current knowledge and research areas that require further clarification are highlighted and suggestions for future directions provided. This review seeks to motivate further research on these enzymes and especially of the lesser known endo-1,4-β-xylanase containing families. A better understanding of these enzymes will serve as a foundation for the knowledge-based development of process-fitted endo-1,4-β-xylanases and will accelerate their development for use with even the most recalcitrant of substrates in the biobased industries of the future.
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Liu J, Zhu J, Xu Q, Shi R, Liu C, Sun D, Liu W. Functional identification of two novel carbohydrate-binding modules of glucuronoxylanase CrXyl30 and their contribution to the lignocellulose saccharification. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2023; 16:40. [PMID: 36890582 PMCID: PMC9996879 DOI: 10.1186/s13068-023-02290-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2022] [Accepted: 02/28/2023] [Indexed: 03/10/2023]
Abstract
BACKGROUND Glycoside hydrolase (GH) family 30 xylanases are a distinct group of xylanases, most of which have a highly specific catalytic activity for glucuronoxylan. Since GH30 xylanases do not normally carry carbohydrate-binding modules (CBMs), our knowledge of the function of their CBMs is lacking. RESULTS In this work, the CBM functions of CrXyl30 were investigated. CrXyl30 was a GH30 glucuronoxylanase containing tandem CBM13 (CrCBM13) and CBM2 (CrCBM2) at its C terminus, which was identified in a lignocellulolytic bacterial consortium previously. Both CBMs could bind insoluble and soluble xylan, with CrCBM13 having binding specificity for the xylan with L-arabinosyl substitutions, whereas CrCBM2 targeted L-arabinosyl side chains themselves. Such binding abilities of these two CBMs were completely different from other CBMs in their respective families. Phylogenetic analysis also suggested that both CrCBM13 and CrCBM2 belong to novel branches. Inspection of the simulated structure of CrCBM13 identified a pocket that just accommodates the side chain of 3(2)-alpha-L-arabinofuranosyl-xylotriose, which forms hydrogen bonds with three of the five amino acid residues involved in ligand interaction. The truncation of either CrCBM13 or CrCBM2 did not alter the substrate specificity and optimal reaction conditions of CrXyl30, whereas truncation of CrCBM2 decreased the kcat/Km value by 83% (± 0%). Moreover, the absence of CrCBM2 and CrCBM13 resulted in a 5% (± 1%) and a 7% (± 0%) decrease, respectively, in the amount of reducing sugar released by the synergistic hydrolysis of delignified corncob whose hemicellulose is arabinoglucuronoxylan, respectively. In addition, fusion of CrCBM2 with a GH10 xylanase enhanced its catalytic activity against the branched xylan and improved the synergistic hydrolysis efficiency by more than fivefold when delignified corncob was used as substrate. Such a strong stimulation of hydrolysis resulted from the enhancement of hemicellulose hydrolysis on the one hand, and the cellulose hydrolysis is also improved according to the lignocellulose conversion rate measured by HPLC. CONCLUSIONS This study identifies the functions of two novel CBMs in CrXyl30 and shows the good potential of such CBMs specific for branched ligands in the development of efficient enzyme preparations.
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Affiliation(s)
- Jiawen Liu
- Jiangsu Key Laboratory of Phylogenomics & Comparative Genomics, School of Life Science, Jiangsu Normal University, No.101, Shanghai Road, Tongshan New District, Xuzhou, 221116, Jiangsu, China
| | - Jingrong Zhu
- Jiangsu Key Laboratory of Phylogenomics & Comparative Genomics, School of Life Science, Jiangsu Normal University, No.101, Shanghai Road, Tongshan New District, Xuzhou, 221116, Jiangsu, China
| | - Qian Xu
- Jiangsu Key Laboratory of Phylogenomics & Comparative Genomics, School of Life Science, Jiangsu Normal University, No.101, Shanghai Road, Tongshan New District, Xuzhou, 221116, Jiangsu, China
| | - Rui Shi
- Jiangsu Key Laboratory of Phylogenomics & Comparative Genomics, School of Life Science, Jiangsu Normal University, No.101, Shanghai Road, Tongshan New District, Xuzhou, 221116, Jiangsu, China
| | - Cong Liu
- Jiangsu Key Laboratory of Phylogenomics & Comparative Genomics, School of Life Science, Jiangsu Normal University, No.101, Shanghai Road, Tongshan New District, Xuzhou, 221116, Jiangsu, China.
| | - Di Sun
- Jiangsu Key Laboratory of Phylogenomics & Comparative Genomics, School of Life Science, Jiangsu Normal University, No.101, Shanghai Road, Tongshan New District, Xuzhou, 221116, Jiangsu, China.
| | - Weijie Liu
- Jiangsu Key Laboratory of Phylogenomics & Comparative Genomics, School of Life Science, Jiangsu Normal University, No.101, Shanghai Road, Tongshan New District, Xuzhou, 221116, Jiangsu, China.
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7
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St John FJ, Crooks C, Kim Y, Tan K, Joachimiak A. The first crystal structure of a xylobiose-bound xylobiohydrolase with high functional specificity from the bacterial glycoside hydrolase 30 subfamily 10. FEBS Lett 2022; 596:2449-2464. [PMID: 35876256 DOI: 10.1002/1873-3468.14454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 07/05/2022] [Accepted: 07/09/2022] [Indexed: 11/05/2022]
Abstract
Xylobiose is a prebiotic sugar that has applications in functional foods. This report describes the first X-ray crystallographic structure models of apo and xylobiose bound forms of a xylobiohydrolase (XBH) from Acetivibrio clariflavus. This xylan active enzyme, a member of the recently described glycoside hydrolase family 30 (GH30) subfamily 10 phylogenetic clade has been shown to strictly release xylobiose as its primary hydrolysis product. Inspection of the apo-structure reveals a glycone region X2 binding slot. When X2 binds, the nonreducing xylose in the -2 subsite is highly coordinated with numerous hydrogen bond contacts while contacts in the -1 subsite mostly reflect interactions typical for GH30 and enzymes in clan A of the carbohydrate-active enzymes database (CAZy). This structure provides an explanation for the high functional specificity of this new bacterial GH30 XBH subfamily.
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Affiliation(s)
- Franz J St John
- Institute for Microbial and Biochemical Technology, Forest Products Laboratory, USDA Forest Service, Madison, WI, 53726, USA
| | - Casey Crooks
- Institute for Microbial and Biochemical Technology, Forest Products Laboratory, USDA Forest Service, Madison, WI, 53726, USA
| | - Youngchang Kim
- Structural Biology Center, X-ray Science Division, Argonne National Laboratory, Lemont, Il, 60439, USA
| | - Kemin Tan
- Structural Biology Center, X-ray Science Division, Argonne National Laboratory, Lemont, Il, 60439, USA
| | - Andrzej Joachimiak
- Structural Biology Center, X-ray Science Division, Argonne National Laboratory, Lemont, Il, 60439, USA.,Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, 60637, USA
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Ordoñez-Arévalo B, Huerta-Lwanga E, Calixto-Romo MDLÁ, Dunn MF, Guillén-Navarro K. Hemicellulolytic bacteria in the anterior intestine of the earthworm Eisenia fetida (Sav.). THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 806:151221. [PMID: 34717991 DOI: 10.1016/j.scitotenv.2021.151221] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2021] [Revised: 10/20/2021] [Accepted: 10/21/2021] [Indexed: 06/13/2023]
Abstract
Tropical agriculture produces large amounts of lignocellulosic residues that can potentially be used as a natural source of value-added products. The complexity of lignocellulose makes industrial-scale processing difficult. New processing techniques must be developed to improve the yield and avoid this valuable resource going to waste. Hemicelluloses comprise a variety of polysaccharides with different backbone compositions and decorations (such as methylations and acetylations), and form part of an intricate framework that confers structural stability to the plant cell wall. Organisms that are able to degrade these biopolymers include earthworms (Eisenia fetida), which can rapidly decompose a wide variety of lignocellulosic substrates. This ability probably derives from enzymes and symbiotic microorganisms in the earthworm gut. In this work, two substrates with similar C/N ratios but different hemicellulose content were selected. Palm fibre and coffee husk have relatively high (28%) and low (5%) hemicellulose contents, respectively. A vermicomposting mixture was prepared for the earthworms to feed on by mixing a hemicellulose substrate with organic market waste. Xylanase activity was determined in earthworm gut and used as a selection criterion for the isolation of hemicellulose-degrading bacteria. Xylanase activity was similar for both substrates, even though their physicochemical properties principally pH and electrical conductivity, as shown by the MANOVA analysis) were different for the total duration of the experiment (120 days). Xylanolytic strains isolated from earthworm gut were identified by sequence analysis of the 16S rRNA gene. Our results indicate that the four Actinobacteria, two Proteobacteria, and one Firmicutes isolated are active participants of the xylanolytic degradation by microbiota in the intestine of E. fetida. Most bacteria were more active at pH 7 and 28 °C, and those with higher activities are reported as being facultatively anaerobic, coinciding with the microenvironment reported for the earthworm gut. Each strain had a different degradative capacity.
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Affiliation(s)
- Berenice Ordoñez-Arévalo
- Grupo Académico de Biotecnología Ambiental, Unidad Tapachula, El Colegio de la Frontera Sur, Carretera Antiguo Aeropuerto Km 2.5, C.P. 30700 Tapachula, Chiapas, Mexico
| | - Esperanza Huerta-Lwanga
- Grupo Académico de Agroecología, El Colegio de la Frontera Sur, Unidad Campeche, Av. Polígono s/n, Ciudad Industrial, C.P. 24500 Lerma, Campeche, Mexico; Soil Physics and Land Management Group, Wageningen University & Research, P.O. Box 47, 6700AA Wageningen, the Netherlands
| | - María de Los Ángeles Calixto-Romo
- Grupo Académico de Biotecnología Ambiental, Unidad Tapachula, El Colegio de la Frontera Sur, Carretera Antiguo Aeropuerto Km 2.5, C.P. 30700 Tapachula, Chiapas, Mexico
| | - Michael Frederick Dunn
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Avenida Universidad s/n, Col. Chamilpa, C.P. 62210 Cuernavaca, Morelos, Mexico
| | - Karina Guillén-Navarro
- Grupo Académico de Biotecnología Ambiental, Unidad Tapachula, El Colegio de la Frontera Sur, Carretera Antiguo Aeropuerto Km 2.5, C.P. 30700 Tapachula, Chiapas, Mexico.
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9
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Nikolaivits E, Pentari C, Kosinas C, Feiler CG, Spiliopoulou M, Weiss MS, Dimarogona M, Topakas E. Unique features of the bifunctional GH30 from Thermothelomyces thermophila revealed by structural and mutational studies. Carbohydr Polym 2021; 273:118553. [PMID: 34560965 DOI: 10.1016/j.carbpol.2021.118553] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 07/21/2021] [Accepted: 08/06/2021] [Indexed: 12/30/2022]
Abstract
Fungal xylanases belonging to family GH30_7, initially categorized as endo-glucuronoxylanases, are now known to differ both in terms of substrate specificity, as well as mode of action. Recently, TtXyn30A, a GH30_7 xylanase from Thermothelomyces thermophila, was shown to possess dual activity, acting on the xylan backbone in both an endo- and an exo- manner. Here, in an effort to identify the structural characteristics that append these functional properties to the enzyme, we present the biochemical characterization of various TtXyn30A mutants as well as its crystal structure, alone, and in complex with the reaction product. An auxiliary catalytic amino acid has been identified, while it is also shown that glucuronic acid recognition is not mediated by a conserved arginine residue, as shown by previously determined GH30 structures.
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Affiliation(s)
- Efstratios Nikolaivits
- Industrial Biotechnology & Biocatalysis Group, Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens, Athens, Greece
| | - Christina Pentari
- Industrial Biotechnology & Biocatalysis Group, Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens, Athens, Greece
| | - Christos Kosinas
- Laboratory of Structural Biology and Biotechnology, Department of Chemical Engineering, University of Patras, Patras, Greece
| | - Christian G Feiler
- Helmholtz-Zentrum Berlin, Macromolecular Crystallography (HZB-MX), Berlin, Germany
| | | | - Manfred S Weiss
- Helmholtz-Zentrum Berlin, Macromolecular Crystallography (HZB-MX), Berlin, Germany
| | - Maria Dimarogona
- Laboratory of Structural Biology and Biotechnology, Department of Chemical Engineering, University of Patras, Patras, Greece.
| | - Evangelos Topakas
- Industrial Biotechnology & Biocatalysis Group, Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens, Athens, Greece.
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10
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Crooks C, Bechle NJ, St John FJ. A New Subfamily of Glycoside Hydrolase Family 30 with Strict Xylobiohydrolase Function. Front Mol Biosci 2021; 8:714238. [PMID: 34557520 PMCID: PMC8453022 DOI: 10.3389/fmolb.2021.714238] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2021] [Accepted: 07/20/2021] [Indexed: 11/13/2022] Open
Abstract
The Acetivibrio clariflavus (basonym: Clostridium clariflavum) glycoside hydrolase family 30 cellulosomal protein encoded by the Clocl_1795 gene was highly represented during growth on cellulosic substrates. In this report, the recombinantly expressed protein has been characterized and shown to be a non-reducing terminal (NRT)-specific xylobiohydrolase (AcXbh30A). Biochemical function, optimal biophysical parameters, and phylogeny were investigated. The findings indicate that AcXbh30A strictly cleaves xylobiose from the NRT up until an α-1,2-linked glucuronic acid (GA)-decorated xylose if the number of xyloses is even or otherwise a single xylose will remain resulting in a penultimate GA-substituted xylose. Unlike recently reported xylobiohydrolases, AcXbh30A has no other detectable hydrolysis products under our optimized reaction conditions. Sequence analysis indicates that AcXbh30A represents a new GH30 subfamily. This new xylobiohydrolase may be useful for commercial production of industrial quantities of xylobiose.
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Affiliation(s)
- Casey Crooks
- Institute for Microbial and Biochemical Technology, Forest Products Laboratory, USDA Forest Service, Madison, WI, United States
| | - Nathan J Bechle
- Engineering Mechanics and Remote Sensing Laboratory, Forest Products Laboratory, USDA Forest Service, Madison, WI, United States
| | - Franz J St John
- Institute for Microbial and Biochemical Technology, Forest Products Laboratory, USDA Forest Service, Madison, WI, United States
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11
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Recent advances in the enzymatic production and applications of xylooligosaccharides. World J Microbiol Biotechnol 2021; 37:169. [PMID: 34487266 DOI: 10.1007/s11274-021-03139-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Accepted: 08/30/2021] [Indexed: 12/20/2022]
Abstract
The majority of lignocellulosic biomass on the planet originates from plant cell walls, which are complex structures build up mainly by cellulose, hemicellulose and lignin. The largest part of hemicellulose, xylan, is a polymer with a β-(1→4)-linked xylose residues backbone decorated with α-D-glucopyranosyl uronic acids and/or L-arabinofuranose residues. Xylan is the second most abundant biopolymer in nature, which can be sustainably and efficiently degraded into decorated and undecorated xylooligosaccharides (XOS) using combinations of thermochemical pretreatments and enzymatic hydrolyses, that have broad applications in the food, feed, pharmaceutical and cosmetic industries. Endo-xylanases from different complex carbohydrate-active enzyme (CAZyme) families can be used to cleave the backbone of arabino(glucurono)xylans and xylooligosaccharides and degrade them into short XOS. It has been shown that XOS with a low degree of polymerization have enhanced prebiotic effects conferring health benefits to humans and animals. In this review we describe recent advances in the enzymatic production of XOS from lignocellulosic biomass arabino- and glucuronoxylans and their applications as food and feed additives and health-promoting ingredients. Comparative advantages of xylanases from different CAZy families in XOS production are discussed and potential health benefits of different XOS are presented.
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12
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Non-Specific GH30_7 Endo-β-1,4-xylanase from Talaromyces leycettanus. Molecules 2021; 26:molecules26154614. [PMID: 34361767 PMCID: PMC8347862 DOI: 10.3390/molecules26154614] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 07/22/2021] [Accepted: 07/27/2021] [Indexed: 01/01/2023] Open
Abstract
This study describes the catalytic properties of a GH30_7 xylanase produced by the fungus Talaromyces leycettanus. The enzyme is an ando-β-1,4-xylanase, showing similar specific activity towards glucuronoxylan, arabinoxylan, and rhodymenan (linear β-1,3-β-1,4-xylan). The heteroxylans are hydrolyzed to a mixture of linear as well as branched β-1,4-xylooligosaccharides that are shorter than the products generated by GH10 and GH11 xylanases. In the rhodymenan hydrolyzate, the linear β-1,4-xylooligosaccharides are accompanied with a series of mixed linkage homologues. Initial hydrolysis of glucuronoxylan resembles the action of other GH30_7 and GH30_8 glucuronoxylanases, resulting in a series of aldouronic acids of a general formula MeGlcA2Xyln. Due to the significant non-specific endoxylanase activity of the enzyme, these acidic products are further attacked in the unbranched regions, finally yielding MeGlcA2Xyl2-3. The accommodation of a substituted xylosyl residue in the −2 subsite also applies in arabinoxylan depolymerization. Moreover, the xylose residue may be arabinosylated at both positions 2 and 3, without negatively affecting the main chain cleavage. The catalytic properties of the enzyme, particularly the great tolerance of the side-chain substituents, make the enzyme attractive for biotechnological applications. The enzyme is also another example of extraordinarily great catalytic diversity among eukaryotic GH30_7 xylanases.
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Šuchová K, Puchart V, Spodsberg N, Mørkeberg Krogh KBR, Biely P. Catalytic Diversity of GH30 Xylanases. Molecules 2021; 26:molecules26154528. [PMID: 34361682 PMCID: PMC8347883 DOI: 10.3390/molecules26154528] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 07/16/2021] [Accepted: 07/23/2021] [Indexed: 11/16/2022] Open
Abstract
Catalytic properties of GH30 xylanases belonging to subfamilies 7 and 8 were compared on glucuronoxylan, modified glucuronoxylans, arabinoxylan, rhodymenan, and xylotetraose. Most of the tested bacterial GH30-8 enzymes are specific glucuronoxylanases (EC 3.2.1.136) requiring for action the presence of free carboxyl group of MeGlcA side residues. These enzymes were not active on arabinoxylan, rhodymenan and xylotetraose, and conversion of MeGlcA to its methyl ester or its reduction to MeGlc led to a remarkable drop in their specific activity. However, some GH30-8 members are nonspecific xylanases effectively hydrolyzing all tested substrates. In terms of catalytic activities, the GH30-7 subfamily is much more diverse. In addition to specific glucuronoxylanases, the GH30-7 subfamily contains nonspecific endoxylanases and predominantly exo-acting enzymes. The activity of GH30-7 specific glucuronoxylanases also depend on the presence of the MeGlcA carboxyl, but not so strictly as in bacterial enzymes. The modification of the carboxyl group of glucuronoxylan had only weak effect on the action of predominantly exo-acting enzymes, as well as nonspecific xylanases. Rhodymenan and xylotetraose were the best substrates for exo-acting enzymes, while arabinoxylan represented hardly degradable substrate for almost all tested GH30-7 enzymes. The results expand current knowledge on the catalytic properties of this relatively novel group of xylanases.
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Affiliation(s)
- Katarína Šuchová
- Institute of Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, 84538 Bratislava, Slovakia; (V.P.); (P.B.)
- Correspondence: ; Tel.: +421-25-941-0229
| | - Vladimír Puchart
- Institute of Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, 84538 Bratislava, Slovakia; (V.P.); (P.B.)
| | - Nikolaj Spodsberg
- Novozymes A/S, Krogshøjvej 36, 2880 Bagsværd, Denmark; (N.S.); (K.B.R.M.K.)
| | | | - Peter Biely
- Institute of Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, 84538 Bratislava, Slovakia; (V.P.); (P.B.)
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Liu J, Sun D, Zhu J, Liu C, Liu W. Carbohydrate-binding modules targeting branched polysaccharides: overcoming side-chain recalcitrance in a non-catalytic approach. BIORESOUR BIOPROCESS 2021; 8:28. [PMID: 38650221 PMCID: PMC10992016 DOI: 10.1186/s40643-021-00381-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2021] [Accepted: 04/07/2021] [Indexed: 12/25/2022] Open
Abstract
Extensive decoration of backbones is a major factor resulting in resistance of enzymatic conversion in hemicellulose and other branched polysaccharides. Employing debranching enzymes is the main strategy to overcome this kind of recalcitrance at present. A carbohydrate-binding module (CBM) is a contiguous amino acid sequence that can promote the binding of enzymes to various carbohydrates, thereby facilitating enzymatic hydrolysis. According to previous studies, CBMs can be classified into four types based on their preference in ligand type, where Type III and IV CBMs prefer to branched polysaccharides than the linear and thus are able to specifically enhance the hydrolysis of substrates containing side chains. With a role in dominating the hydrolysis of branched substrates, Type III and IV CBMs could represent a non-catalytic approach in overcoming side-chain recalcitrance.
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Affiliation(s)
- Jiawen Liu
- Jiangsu Key Laboratory of Phylogenomics & Comparative Genomics, School of Life Science, Jiangsu Normal University, No. 101, Shanghai Road, Tongshan New District, Xuzhou, 221116, Jiangsu, China
| | - Di Sun
- Jiangsu Key Laboratory of Phylogenomics & Comparative Genomics, School of Life Science, Jiangsu Normal University, No. 101, Shanghai Road, Tongshan New District, Xuzhou, 221116, Jiangsu, China
| | - Jingrong Zhu
- Jiangsu Key Laboratory of Phylogenomics & Comparative Genomics, School of Life Science, Jiangsu Normal University, No. 101, Shanghai Road, Tongshan New District, Xuzhou, 221116, Jiangsu, China
| | - Cong Liu
- Jiangsu Key Laboratory of Phylogenomics & Comparative Genomics, School of Life Science, Jiangsu Normal University, No. 101, Shanghai Road, Tongshan New District, Xuzhou, 221116, Jiangsu, China.
| | - Weijie Liu
- Jiangsu Key Laboratory of Phylogenomics & Comparative Genomics, School of Life Science, Jiangsu Normal University, No. 101, Shanghai Road, Tongshan New District, Xuzhou, 221116, Jiangsu, China.
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15
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Baker JT, Duarte ME, Holanda DM, Kim SW. Friend or Foe? Impacts of Dietary Xylans, Xylooligosaccharides, and Xylanases on Intestinal Health and Growth Performance of Monogastric Animals. Animals (Basel) 2021; 11:609. [PMID: 33652614 PMCID: PMC7996850 DOI: 10.3390/ani11030609] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 02/11/2021] [Accepted: 02/24/2021] [Indexed: 12/27/2022] Open
Abstract
This paper discusses the structural difference and role of xylan, procedures involved in the production of xylooligosaccharides (XOS), and their implementation into animal feeds. Xylan is non-starch polysaccharides that share a β-(1-4)-linked xylopyranose backbone as a common feature. Due to the myriad of residues that can be substituted on the polymers within the xylan family, more anti-nutritional factors are associated with certain types of xylan than others. XOS are sugar oligomers extracted from xylan-containing lignocellulosic materials, such as crop residues, wood, and herbaceous biomass, that possess prebiotic effects. XOS can also be produced in the intestine of monogastric animals to some extent when exogenous enzymes, such as xylanase, are added to the feed. Xylanase supplementation is a common practice within both swine and poultry production to reduce intestinal viscosity and improve digestive utilization of nutrients. The efficacy of xylanase supplementation varies widely due a number of factors, one of which being the presence of xylanase inhibitors present in common feedstuffs. The use of prebiotics in animal feeding is gaining popularity as producers look to accelerate growth rate, enhance intestinal health, and improve other production parameters in an attempt to provide a safe and sustainable food product. Available research on the impact of xylan, XOS, as well as xylanase on the growth and health of swine and poultry, is also summarized. The response to xylanase supplementation in swine and poultry feeds is highly variable and whether the benefits are a result of nutrient release from NSP, reduction in digesta viscosity, production of short chain xylooligosaccharides or a combination of these is still in question. XOS supplementation seems to benefit both swine and poultry at various stages of production, as well as varying levels of XOS purity and degree of polymerization; however, further research is needed to elucidate the ideal dosage, purity, and degree of polymerization needed to confer benefits on intestinal health and performance in each respective species.
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Affiliation(s)
| | | | | | - Sung Woo Kim
- Department of Animal Science, North Carolina State University, Raleigh, NC 27695, USA; (J.T.B.); (M.E.D.); (D.M.H.)
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16
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Xylanases of glycoside hydrolase family 30 - An overview. Biotechnol Adv 2021; 47:107704. [PMID: 33548454 DOI: 10.1016/j.biotechadv.2021.107704] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 01/23/2021] [Accepted: 01/25/2021] [Indexed: 12/22/2022]
Abstract
Xylan is the most abundant hemicellulose in nature and as such it is a huge source of renewable carbon. Its bioconversion requires a battery of xylanolytic enzymes. Of them the most important are the endo-β-1,4-xylanases which depolymerize the polysaccharide into smaller fragments. Most of the xylanases are members of glycoside hydrolase (GH) families 10 and 11, although they are classified in some other GH families. The relatively new xylanases of GH30 are of special interest. Initially, they appeared to be specific glucuronoxylanases, however, other specificities were found later among prokaryotic and in particular eukaryotic enzymes. This review gives an overview of the substrate and product specificities observed for the GH30 xylanases characterized to date. An emphasis is given to the structure-activity relationship in order to explain how minor differences in catalytic centre and its vicinity can alter catalytic properties from the endoxylanase into the reducing end xylose releasing exoxylanase or into the non-reducing end xylobiohydrolase. Biotechnological potential of the GH30 xylanases is also considered.
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17
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Hero JS, Pisa JH, Raimondo EE, Martínez MA. Proteomic analysis of secretomes from Bacillus sp. AR03: characterization of enzymatic cocktails active on complex carbohydrates for xylooligosaccharides production. Prep Biochem Biotechnol 2021; 51:871-880. [PMID: 33439095 DOI: 10.1080/10826068.2020.1870136] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Bacillus sp. AR03 have been described as an important producer of carbohydrate-active enzymes (CAZymes) when growing in a peptone-based medium supplemented with simple sugars and/or carboxymethyl cellulose (CMC) as carbon sources. This work aimed to identify the extracellular enzymatic cocktails through shotgun proteomics. The proteomic analysis showed that enzymes involved in cellulose and xylan degradation were among the most abundant proteins. These enzymes included an endo-glucanase GH5_2 and a glucuronoxylanase GH30_8, which were found in all conditions. In addition, several proteins were differentially expressed in the three evaluated culture media, indicating microbial metabolic changes due to the different supplied carbon sources, particularly, in the presence of CMC. Finally, the capability of the crude enzymatic cocktails from culture media to degrade birchwood xylan was assessed, which produced mostly xylooligosaccharides containing among 3-5 xylose units. Consequently, this work shows the potential of the extracellular enzymes from Bacillus sp. AR03 for producing emergent prebiotics.
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Affiliation(s)
- Johan S Hero
- Planta Piloto de Procesos Industriales Microbiológicos (PROIMI), CONICET, Tucumán, Argentina
| | - José H Pisa
- Planta Piloto de Procesos Industriales Microbiológicos (PROIMI), CONICET, Tucumán, Argentina
| | - Enzo E Raimondo
- Planta Piloto de Procesos Industriales Microbiológicos (PROIMI), CONICET, Tucumán, Argentina.,Facultad de Bioquímica, Química y Farmacia, Universidad Nacional de Tucumán, Tucumán, Argentina
| | - M Alejandra Martínez
- Planta Piloto de Procesos Industriales Microbiológicos (PROIMI), CONICET, Tucumán, Argentina.,Facultad de Ciencias Exactas y Tecnología, Universidad Nacional de Tucumán, Tucumán, Argentina
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18
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A novel bacterial GH30 xylobiohydrolase from Hungateiclostridium clariflavum. Appl Microbiol Biotechnol 2020; 105:185-195. [PMID: 33215261 DOI: 10.1007/s00253-020-11023-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2020] [Revised: 10/23/2020] [Accepted: 11/12/2020] [Indexed: 10/23/2022]
Abstract
Typical bacterial GH30 xylanases are glucuronoxylanases requiring 4-O-methylglucuronic acid (MeGlcA) substitution of a xylan main chain for their action. They do not exhibit a significant activity on neutral xylooligosaccharides, arabinoxylan (AraX), or rhodymenan (Rho). In this work, the biochemical characterization of the bacterial Clocl_1795 xylanase from Hungateiclostridium (Clostridium) clariflavum DSM 19732 (HcXyn30A) is presented. Amino acid sequence analysis of HcXyn30A revealed that the enzyme does not contain amino acids known to be responsible for MeGlcA coordination in the -2b subsite of glucuronoxylanases. This suggested that the catalytic properties of HcXyn30A may differ from those of glucuronoxylanases. HcXyn30A shows similar specific activity on glucuronoxylan (GX) and Rho, while the specific activity on AraX is about 1000 times lower. HcXyn30A releases Xyl2 as the main product from the non-reducing end of different polymeric and oligomeric substrates. Catalytic properties of HcXyn30A resemble the properties of the fungal GH30 xylobiohydrolase from Acremonium alcalophilum, AaXyn30A. HcXyn30A is the first representative of a prokaryotic xylobiohydrolase. Its unique specificity broadens the catalytic diversity of bacterial GH30 xylanases. KEY POINTS: • Bacterial GH30 xylobiohydrolase from H. clariflavum (HcXyn30A) has been characterized. • HcXyn30A releases xylobiose from the non-reducing end of different substrates. • HcXyn30A is the first representative of bacterial xylobiohydrolase.
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19
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Barrett K, Hunt CJ, Lange L, Meyer AS. Conserved unique peptide patterns (CUPP) online platform: peptide-based functional annotation of carbohydrate active enzymes. Nucleic Acids Res 2020; 48:W110-W115. [PMID: 32406917 PMCID: PMC7319580 DOI: 10.1093/nar/gkaa375] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2020] [Revised: 04/28/2020] [Accepted: 05/12/2020] [Indexed: 11/13/2022] Open
Abstract
The CUPP platform includes a web server for functional annotation and sub-grouping of carbohydrate active enzymes (CAZymes) based on a novel peptide-based similarity assessment algorithm, i.e. protein grouping according to Conserved Unique Peptide Patterns (CUPP). This online platform is open to all users and there is no login requirement. The web server allows the user to perform genome-based annotation of carbohydrate active enzymes to CAZy families, CAZy subfamilies, CUPP groups and EC numbers (function) via assessment of peptide-motifs by CUPP. The web server is intended for functional annotation assessment of the CAZy inventory of prokaryotic and eukaryotic organisms from genomic DNA (up to 30MB compressed) or directly from amino acid sequences (up to 10MB compressed). The custom query sequences are assessed using the CUPP annotation algorithm, and the outcome is displayed in interactive summary result pages of CAZymes. The results displayed allow for inspection of members of the individual CUPP groups and include information about experimentally characterized members. The web server and the other resources on the CUPP platform can be accessed from https://cupp.info.
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Affiliation(s)
- Kristian Barrett
- Protein Chemistry and Enzyme Technology Section, DTU Bioengineering, Department of Biotechnology and Biomedicine, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
| | - Cameron J Hunt
- Protein Chemistry and Enzyme Technology Section, DTU Bioengineering, Department of Biotechnology and Biomedicine, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
| | - Lene Lange
- LLa-BioEconomy, Research & Advisory, 2500 Valby, Denmark
| | - Anne S Meyer
- Protein Chemistry and Enzyme Technology Section, DTU Bioengineering, Department of Biotechnology and Biomedicine, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
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20
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Wood hemicelluloses exert distinct biomechanical contributions to cellulose fibrillar networks. Nat Commun 2020; 11:4692. [PMID: 32943624 PMCID: PMC7499266 DOI: 10.1038/s41467-020-18390-z] [Citation(s) in RCA: 67] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Accepted: 08/20/2020] [Indexed: 12/03/2022] Open
Abstract
Hemicelluloses, a family of heterogeneous polysaccharides with complex molecular structures, constitute a fundamental component of lignocellulosic biomass. However, the contribution of each hemicellulose type to the mechanical properties of secondary plant cell walls remains elusive. Here we homogeneously incorporate different combinations of extracted and purified hemicelluloses (xylans and glucomannans) from softwood and hardwood species into self-assembled networks during cellulose biosynthesis in a bacterial model, without altering the morphology and the crystallinity of the cellulose bundles. These composite hydrogels can be therefore envisioned as models of secondary plant cell walls prior to lignification. The incorporated hemicelluloses exhibit both a rigid phase having close interactions with cellulose, together with a flexible phase contributing to the multiscale architecture of the bacterial cellulose hydrogels. The wood hemicelluloses exhibit distinct biomechanical contributions, with glucomannans increasing the elastic modulus in compression, and xylans contributing to a dramatic increase of the elongation at break under tension. These diverging effects cannot be explained solely from the nature of their direct interactions with cellulose, but can be related to the distinct molecular structure of wood xylans and mannans, the multiphase architecture of the hydrogels and the aggregative effects amongst hemicellulose-coated fibrils. Our study contributes to understanding the specific roles of wood xylans and glucomannans in the biomechanical integrity of secondary cell walls in tension and compression and has significance for the development of lignocellulosic materials with controlled assembly and tailored mechanical properties. Hemicelluloses are an essential constituent of plant cell walls, but the individual biomechanical roles remain elusive. Here the authors report on the interaction of wood hemicellulose with bacterial cellulose during deposition and explore the resultant fibrillar architecture and mechanical properties.
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21
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Nakamichi Y, Fujii T, Watanabe M, Matsushika A, Inoue H. Crystal structure of GH30-7 endoxylanase C from the filamentous fungus Talaromyces cellulolyticus. Acta Crystallogr F Struct Biol Commun 2020; 76:341-349. [PMID: 32744245 PMCID: PMC7397468 DOI: 10.1107/s2053230x20009024] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2020] [Accepted: 07/02/2020] [Indexed: 11/11/2022] Open
Abstract
GH30-7 endoxylanase C from the cellulolytic fungus Talaromyces cellulolyticus (TcXyn30C) belongs to glycoside hydrolase family 30 subfamily 7, and specifically releases 22-(4-O-methyl-α-D-glucuronosyl)-xylobiose from glucuronoxylan, as well as various arabino-xylooligosaccharides from arabinoxylan. TcXyn30C has a modular structure consisting of a catalytic domain and a C-terminal cellulose-binding module 1 (CBM1). In this study, the crystal structure of a TcXyn30C mutant which lacks the CBM1 domain was determined at 1.65 Å resolution. The structure of the active site of TcXyn30C was compared with that of the bifunctional GH30-7 xylanase B from T. cellulolyticus (TcXyn30B), which exhibits glucuronoxylanase and xylobiohydrolase activities. The results revealed that TcXyn30C has a conserved structural feature for recognizing the 4-O-methyl-α-D-glucuronic acid (MeGlcA) substituent in subsite -2b. Additionally, the results demonstrated that Phe47 contributes significantly to catalysis by TcXyn30C. Phe47 is located in subsite -2b and also near the C-3 hydroxyl group of a xylose residue in subsite -2a. Substitution of Phe47 with an arginine residue caused a remarkable decrease in the catalytic efficiency towards arabinoxylan, suggesting the importance of Phe47 in arabinoxylan hydrolysis. These findings indicate that subsite -2b of TcXyn30C has unique structural features that interact with arabinofuranose and MeGlcA substituents.
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Affiliation(s)
- Yusuke Nakamichi
- Bioconversion Group, Research Institute for Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), 3-11-32 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-0046, Japan
| | - Tatsuya Fujii
- Bioconversion Group, Research Institute for Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), 3-11-32 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-0046, Japan
| | - Masahiro Watanabe
- Bioconversion Group, Research Institute for Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), 3-11-32 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-0046, Japan
| | - Akinori Matsushika
- Bioconversion Group, Research Institute for Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), 3-11-32 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-0046, Japan
- Graduate School of Advanced Sciences of Matter, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan
| | - Hiroyuki Inoue
- Bioconversion Group, Research Institute for Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), 3-11-32 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-0046, Japan
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22
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Crooks C, Long L, St John FJ. CaXyn30B from the solventogenic bacterium Clostridium acetobutylicum is a glucuronic acid-dependent endoxylanase. BMC Res Notes 2020; 13:281. [PMID: 32522254 PMCID: PMC7285738 DOI: 10.1186/s13104-020-05091-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Accepted: 05/16/2020] [Indexed: 11/24/2022] Open
Abstract
Objective We previously described the structure and activity of a glycoside hydrolase family 30 subfamily 8 (GH30-8) endoxylanase, CaXyn30A, from Clostridium acetobutylicum which exhibited novel glucuronic acid (GA)-independent activity. Immediately downstream from CaXyn30A is encoded another GH30-8 enzyme, CaXyn30B. While CaXyn30A deviated substantially in the highly conserved β7-α7 and β8-α8 loop regions of the catalytic cleft which are responsible for GA-dependence, CaXyn30B maintains these conserved subfamily 8 amino acid residues thus predicting canonical GA-dependent activity. In this report, we show that CaXyn30B functions as a canonical GA-dependent GH30-8 endoxylanase in contrast to its GA-independent neighbor, CaXyn30A. Results A clone expressing the catalytic domain of CaXyn30B (CaXyn30B-CD) exhibited GA-dependent endoxylanase activity. Digestion of glucuronoxylan generated a ladder of aldouronate limit products as anticipated for canonical GA-dependent GH30-8 enzymes. Unlike the previously described CaXyn30A-CD, CaXyn30B-CD showed no activity on arabinoxylan or the generation of appreciable neutral oligosaccharides from glucuronoxylan substrates. These results are consistent with amino acid sequence comparisons of the catalytic cleft and phylogenetic analysis.
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Affiliation(s)
- Casey Crooks
- Institute for Microbial and Biochemical Technology, Forest Products Laboratory, USDA Forest Service, One Gifford Pinchot Drive, Madison, WI, 53726, USA.
| | - Liangkun Long
- Institute for Microbial and Biochemical Technology, Forest Products Laboratory, USDA Forest Service, One Gifford Pinchot Drive, Madison, WI, 53726, USA.,College of Chemical Engineering, Nanjing Forestry University, Nanjing, 210037, China
| | - Franz J St John
- Institute for Microbial and Biochemical Technology, Forest Products Laboratory, USDA Forest Service, One Gifford Pinchot Drive, Madison, WI, 53726, USA
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23
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Nakamichi Y, Watanabe M, Matsushika A, Inoue H. Substrate recognition by a bifunctional GH30-7 xylanase B from Talaromyces cellulolyticus. FEBS Open Bio 2020; 10:1180-1189. [PMID: 32359208 PMCID: PMC7262913 DOI: 10.1002/2211-5463.12873] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2020] [Revised: 04/23/2020] [Accepted: 04/28/2020] [Indexed: 11/07/2022] Open
Abstract
Xylanase B, a member of subfamily 7 of the GH30 (glycoside hydrolase family 30) from Talaromyces cellulolyticus (TcXyn30B), is a bifunctional enzyme with glucuronoxylanase and xylobiohydrolase activities. In the present study, crystal structures of the native enzyme and the enzyme–product complex of TcXyn30B expressed in Pichia pastoris were determined at resolutions of 1.60 and 1.65 Å, respectively. The enzyme complexed with 22‐(4‐O‐methyl‐α‐d‐glucuronyl)‐xylobiose (U4m2X) revealed that TcXyn30B strictly recognizes both the C‐6 carboxyl group and the 4‐O‐methyl group of the 4‐O‐methyl‐α‐d‐glucuronyl side chain by the conserved residues in GH30‐7 endoxylanases. The crystal structure and site‐directed mutagenesis indicated that Asn‐93 on the β2‐α2‐loop interacts with the non‐reducing end of the xylose residue at subsite‐2 and is likely to be involved in xylobiohydrolase activity. These findings provide structural insight into the mechanisms of substrate recognition of GH30‐7 glucuronoxylanase and xylobiohydrolase.
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Affiliation(s)
- Yusuke Nakamichi
- Research Institute for Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), Higashi-Hiroshima, Japan
| | - Masahiro Watanabe
- Research Institute for Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), Higashi-Hiroshima, Japan
| | - Akinori Matsushika
- Research Institute for Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), Higashi-Hiroshima, Japan.,Graduate School of Integrated Sciences for Life, Hiroshima University, Higashi-Hiroshima, Japan
| | - Hiroyuki Inoue
- Research Institute for Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), Higashi-Hiroshima, Japan
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24
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Underlin EN, d'Errico C, Böhm M, Madsen R. Synthesis of Glucuronoxylan Hexasaccharides by Preactivation-Based Glycosylations. European J Org Chem 2020. [DOI: 10.1002/ejoc.202000211] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Emilie N. Underlin
- Department of Chemistry; Technical University of Denmark; 2800 Kgs. Lyngby Denmark
| | - Clotilde d'Errico
- Department of Chemistry; Technical University of Denmark; 2800 Kgs. Lyngby Denmark
| | - Maximilian Böhm
- Department of Chemistry; Technical University of Denmark; 2800 Kgs. Lyngby Denmark
| | - Robert Madsen
- Department of Chemistry; Technical University of Denmark; 2800 Kgs. Lyngby Denmark
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25
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Jiménez‐Ortega E, Valenzuela S, Ramírez‐Escudero M, Pastor FJ, Sanz‐Aparicio J. Structural analysis of the reducing‐end xylose‐releasing exo‐oligoxylanase Rex8A from
Paenibacillus barcinonensis
BP‐23 deciphers its molecular specificity. FEBS J 2020; 287:5362-5374. [DOI: 10.1111/febs.15332] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 03/27/2020] [Accepted: 04/09/2020] [Indexed: 12/26/2022]
Affiliation(s)
- Elena Jiménez‐Ortega
- Macromolecular Crystallography and Structural Biology Department Institute of Physical‐Chemistry ‘Rocasolano’ CSIC Madrid Spain
| | - Susana Valenzuela
- Department of Microbiology Faculty of Biology University of Barcelona Spain
- Institute of Nanoscience and Nanotechnology (IN2UB) University of Barcelona Spain
| | - Mercedes Ramírez‐Escudero
- Macromolecular Crystallography and Structural Biology Department Institute of Physical‐Chemistry ‘Rocasolano’ CSIC Madrid Spain
| | - Francisco Javier Pastor
- Department of Microbiology Faculty of Biology University of Barcelona Spain
- Institute of Nanoscience and Nanotechnology (IN2UB) University of Barcelona Spain
| | - Julia Sanz‐Aparicio
- Macromolecular Crystallography and Structural Biology Department Institute of Physical‐Chemistry ‘Rocasolano’ CSIC Madrid Spain
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26
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Šuchová K, Puchart V, Spodsberg N, Mørkeberg Krogh KBR, Biely P. A novel GH30 xylobiohydrolase from Acremonium alcalophilum releasing xylobiose from the non-reducing end. Enzyme Microb Technol 2019; 134:109484. [PMID: 32044031 DOI: 10.1016/j.enzmictec.2019.109484] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2019] [Revised: 11/28/2019] [Accepted: 11/29/2019] [Indexed: 12/21/2022]
Abstract
Xylanases of the GH30 family are grouped to subfamilies GH30-7 and GH30-8. The GH30-8 members are of bacterial origin and well characterized, while the GH30-7 members are from fungal sources and their properties are quite diverse. Here, a heterologous expression and characterization of the GH30-7 xylanase AaXyn30A from a cellulolytic fungus Acremonium alcalophilum is reported. From various polymeric and oligomeric substrates AaXyn30A generates xylobiose as the main product. It was proven that xylobiose is released from the non-reducing end of all tested substrates, thus the enzyme behaves as a typical non-reducing-end acting xylobiohydrolase. AaXyn30A is active on different types of xylan, exhibiting the highest activity on rhodymenan (linear β-1,3-β-1,4-xylan) from which also an isomeric xylotriose Xyl-β-1,3-Xyl-β-1,4-Xyl is formed. Production of xylobiose from glucuronoxylan is at later stage accompanied by a release of aldouronic acids differing from those liberated by the bacterial GH30-8 glucuronoxylanases.
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Affiliation(s)
- Katarína Šuchová
- Institute of Chemistry, Slovak Academy of Sciences, Bratislava, Slovakia.
| | - Vladimír Puchart
- Institute of Chemistry, Slovak Academy of Sciences, Bratislava, Slovakia
| | | | | | - Peter Biely
- Institute of Chemistry, Slovak Academy of Sciences, Bratislava, Slovakia
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27
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Mode of Action of GH30-7 Reducing-End Xylose-Releasing Exoxylanase A (Xyn30A) from the Filamentous Fungus Talaromyces cellulolyticus. Appl Environ Microbiol 2019; 85:AEM.00552-19. [PMID: 31003983 DOI: 10.1128/aem.00552-19] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2019] [Accepted: 04/14/2019] [Indexed: 11/20/2022] Open
Abstract
In this study, we characterized the mode of action of reducing-end xylose-releasing exoxylanase (Rex), which belongs to the glycoside hydrolase family 30-7 (GH30-7). GH30-7 Rex, isolated from the cellulolytic fungus Talaromyces cellulolyticus (Xyn30A), exists as a dimer. The purified Xyn30A released xylose from linear xylooligosaccharides (XOSs) 3 to 6 xylose units in length with similar kinetic constants. Hydrolysis of branched, borohydride-reduced, and p-nitrophenyl XOSs clarified that Xyn30A possesses a Rex activity. 1H nuclear magnetic resonance (1H NMR) analysis of xylotriose hydrolysate indicated that Xyn30A degraded XOSs via a retaining mechanism and without recognizing an anomeric structure at the reducing end. Hydrolysis of xylan by Xyn30A revealed that the enzyme continuously liberated both xylose and two types of acidic XOSs: 22-(4-O-methyl-α-d-glucuronyl)-xylotriose (MeGlcA2Xyl3) and 22-(MeGlcA)-xylobiose (MeGlcA2Xyl2). These acidic products were also detected during hydrolysis using a mixture of MeGlcA2Xyl n (n = 2 to 14) as the substrate. This indicates that Xyn30A can release MeGlcA2Xyl n (n = 2 and 3) in an exo manner. Comparison of subsites in Xyn30A and GH30-7 glucuronoxylanase using homology modeling suggested that the binding of the reducing-end residue at subsite +2 was partially prevented by a Gln residue conserved in GH30-7 Rex; additionally, the Arg residue at subsite -2b, which is conserved in glucuronoxylanase, was not found in Xyn30A. Our results lead us to propose that GH30-7 Rex plays a complementary role in hydrolysis of xylan by fungal cellulolytic systems.IMPORTANCE Endo- and exo-type xylanases depolymerize xylan and play crucial roles in the assimilation of xylan in bacteria and fungi. Exoxylanases release xylose from the reducing or nonreducing ends of xylooligosaccharides; this is generated by the activity of endoxylanases. β-Xylosidase, which hydrolyzes xylose residues on the nonreducing end of a substrate, is well studied. However, the function of reducing-end xylose-releasing exoxylanases (Rex), especially in fungal cellulolytic systems, remains unclear. This study revealed the mode of xylan hydrolysis by Rex from the cellulolytic fungus Talaromyces cellulolyticus (Xyn30A), which belongs to the glycoside hydrolase family 30-7 (GH30-7). A conserved residue related to Rex activity is found in the substrate-binding site of Xyn30A. These findings will enhance our understanding of the function of GH30-7 Rex in the cooperative hydrolysis of xylan by fungal enzymes.
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28
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Barrett K, Lange L. Peptide-based functional annotation of carbohydrate-active enzymes by conserved unique peptide patterns (CUPP). BIOTECHNOLOGY FOR BIOFUELS 2019; 12:102. [PMID: 31168320 PMCID: PMC6489277 DOI: 10.1186/s13068-019-1436-5] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Accepted: 04/13/2019] [Indexed: 05/24/2023]
Abstract
BACKGROUND Insight into the function of carbohydrate-active enzymes is required to understand their biological role and industrial potential. There is a need for better use of the ample genomic data in order to enable selection of the most interesting proteins for further studies. The basis for elaborating a new approach to sequence analysis is the hypothesis that when using conserved peptide patterns to determine the similarities between proteins, the exact spacing between conserved adjacent amino acids in the proteins plays a prominent functional role. Thus, the objective of developing the method of conserved unique peptide patterns (CUPP) is to construct a peptide-based grouping and validate the method to provide evidence that CUPP captures function-related features of the individual carbohydrate-active enzymes (as defined by CAZy families). This approach facilitates grouping of enzymes at a level lower than protein families and/or subfamilies. A standardized, efficient, and robust approach to functional annotation of carbohydrate-active enzymes would support improved molecular insight into enzyme-substrate interaction. RESULTS A new nonalignment-based clustering and functional annotation tool was developed that uses conserved unique peptides patterns to perform automated clustering of proteins and formation of protein groups. A peptide-based model was constructed for each of these protein CUPP groups to be used to automatically annotate protein family, subfamily, and EC function of carbohydrate-active enzymes. CUPP prediction can annotate proteins (from any CAZy family) with high F-score to existing family (0.966), subfamily (0.961), and EC-function (0.843). The speed of the CUPP program was estimated and exemplified by prediction of the 504,017 nonredundant proteins of CAZy in less than four CPU hours. CONCLUSION It was possible to construct an automated system for clustering proteins within families and use the resulting CUPP groups to directly build peptide-based models for genome annotation. The CUPP runtime, F-score, sensitivity, and precisions of family and subfamily annotations match or represent an improvement compared to state-of-the-art tools. The speed of the CUPP annotation is similar to the rapid DIAMOND annotation tool. CUPP facilitates automated annotation of full genome assemblies to any CAZy family.
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Affiliation(s)
- Kristian Barrett
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Lene Lange
- BioEconomy, Research & Advisory, Valby, Denmark
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29
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Nakamichi Y, Fouquet T, Ito S, Watanabe M, Matsushika A, Inoue H. Structural and functional characterization of a bifunctional GH30-7 xylanase B from the filamentous fungus Talaromyces cellulolyticus. J Biol Chem 2019; 294:4065-4078. [PMID: 30655295 DOI: 10.1074/jbc.ra118.007207] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2018] [Revised: 01/15/2019] [Indexed: 01/11/2023] Open
Abstract
Glucuronoxylanases are endo-xylanases and members of the glycoside hydrolase family 30 subfamilies 7 (GH30-7) and 8 (GH30-8). Unlike for the well-studied GH30-8 enzymes, the structural and functional characteristics of GH30-7 enzymes remain poorly understood. Here, we report the catalytic properties and three-dimensional structure of GH30-7 xylanase B (Xyn30B) identified from the cellulolytic fungus Talaromyces cellulolyticus Xyn30B efficiently degraded glucuronoxylan to acidic xylooligosaccharides (XOSs), including an α-1,2-linked 4-O-methyl-d-glucuronosyl substituent (MeGlcA). Rapid analysis with negative-mode electrospray-ionization multistage MS (ESI(-)-MS n ) revealed that the structures of the acidic XOS products are the same as those of the hydrolysates (MeGlcA2Xyl n , n > 2) obtained with typical glucuronoxylanases. Acidic XOS products were further degraded by Xyn30B, releasing first xylobiose and then xylotetraose and xylohexaose as transglycosylation products. This hydrolase reaction was unique to Xyn30B, and the substrate was cleaved at the xylobiose unit from its nonreducing end, indicating that Xyn30B is a bifunctional enzyme possessing both endo-glucuronoxylanase and exo-xylobiohydrolase activities. The crystal structure of Xyn30B was determined as the first structure of a GH30-7 xylanase at 2.25 Å resolution, revealing that Xyn30B is composed of a pseudo-(α/β)8-catalytic domain, lacking an α6 helix, and a small β-rich domain. This structure and site-directed mutagenesis clarified that Arg46, conserved in GH30-7 glucuronoxylanases, is a critical residue for MeGlcA appendage-dependent xylan degradation. The structural comparison between Xyn30B and the GH30-8 enzymes suggests that Asn93 in the β2-α2 loop is involved in xylobiohydrolase activity. In summary, our findings indicate that Xyn30B is a bifunctional endo- and exo-xylanase.
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Affiliation(s)
| | - Thierry Fouquet
- the Polymer Chemistry Group, Research Institute for Sustainable Chemistry, AIST, 1-1-1 Higashi, Tsukuba, Ibaraki 305-8565, Japan, and
| | - Shotaro Ito
- the Bio-based Materials Chemistry Group, Research Institute for Sustainable Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), 3-11-32 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-0046, Japan
| | | | - Akinori Matsushika
- From the Bioconversion Group and.,the Graduate School of Advanced Sciences of Matter, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima, Hiroshima 739-8530, Japan
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30
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Mamo G. Alkaline Active Hemicellulases. ADVANCES IN BIOCHEMICAL ENGINEERING/BIOTECHNOLOGY 2019; 172:245-291. [PMID: 31372682 DOI: 10.1007/10_2019_101] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Xylan and mannan are the two most abundant hemicelluloses, and enzymes that modify these polysaccharides are prominent hemicellulases with immense biotechnological importance. Among these enzymes, xylanases and mannanases which play the vital role in the hydrolysis of xylan and mannan, respectively, attracted a great deal of interest. These hemicellulases have got applications in food, feed, bioethanol, pulp and paper, chemical, and beverage producing industries as well as in biorefineries and environmental biotechnology. The great majority of the enzymes used in these applications are optimally active in mildly acidic to neutral range. However, in recent years, alkaline active enzymes have also become increasingly important. This is mainly due to some benefits of utilizing alkaline active hemicellulases over that of neutral or acid active enzymes. One of the advantages is that the alkaline active enzymes are most suitable to applications that require high pH such as Kraft pulp delignification, detergent formulation, and cotton bioscouring. The other benefit is related to the better solubility of hemicelluloses at high pH. Since the efficiency of enzymatic hydrolysis is often positively correlated to substrate solubility, the hydrolysis of hemicelluloses can be more efficient if performed at high pH. High pH hydrolysis requires the use of alkaline active enzymes. Moreover, alkaline extraction is the most common hemicellulose extraction method, and direct hydrolysis of the alkali-extracted hemicellulose could be of great interest in the valorization of hemicellulose. Direct hydrolysis avoids the time-consuming extensive washing, and neutralization processes required if non-alkaline active enzymes are opted to be used. Furthermore, most alkaline active enzymes are relatively active in a wide range of pH, and at least some of them are significantly or even optimally active in slightly acidic to neutral pH range. Such enzymes can be eligible for non-alkaline applications such as in feed, food, and beverage industries.This chapter largely focuses on the most important alkaline active hemicellulases, endo-β-1,4-xylanases and β-mannanases. It summarizes the relevant catalytic properties, structural features, as well as the real and potential applications of these remarkable hemicellulases in textile, paper and pulp, detergent, feed, food, and prebiotic producing industries. In addition, the chapter depicts the role of these extremozymes in valorization of hemicelluloses to platform chemicals and alike in biorefineries. It also reviews hemicelluloses and discusses their biotechnological importance.
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31
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Nordberg Karlsson E, Schmitz E, Linares-Pastén JA, Adlercreutz P. Endo-xylanases as tools for production of substituted xylooligosaccharides with prebiotic properties. Appl Microbiol Biotechnol 2018; 102:9081-9088. [PMID: 30196329 PMCID: PMC6208967 DOI: 10.1007/s00253-018-9343-4] [Citation(s) in RCA: 90] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Revised: 08/16/2018] [Accepted: 08/19/2018] [Indexed: 01/14/2023]
Abstract
Xylan has a main chain consisting of β-1,4-linked xylose residues with diverse substituents. Endoxylanases cleave the xylan chain at cleavage sites determined by the substitution pattern and thus give different oligosaccharide product patterns. Most known endoxylanases belong to glycoside hydrolase (GH) families 10 and 11. These enzymes work well on unsubstituted xylan but accept substituents in certain subsites. The GH11 enzymes are more restricted by substituents, but on the other hand, they are normally more active than the GH10 enzymes on insoluble substrates, because of their smaller size. GH5 endoxylanases accept arabinose substituents in several subsites and require it in the - 1 subsite. This specificity makes the GH5 endoxylanases very useful for degradation of highly arabinose-substituted xylans and for the selective production of arabinoxylooligosaccharides, without formation of unsubstituted xylooligosaccharides. The GH30 endoxylanases have a related type of specificity in that they require a uronic acid substituent in the - 2 subsite, which makes them very useful for the production of uronic acid substituted oligosaccharides. The ability of dietary xylooligosaccharides to function as prebiotics in humans is governed by their substitution patterns. Endoxylanases are thus excellent tools to tailor prebiotic oligosaccharides to stimulate various types of intestinal bacteria and to cause fermentation in different parts of the gastrointestinal tract. Continuously increasing knowledge on the function of the gut microbiota and discoveries of novel endoxylanases increase the possibilities to achieve health-promoting effects.
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Affiliation(s)
| | - Eva Schmitz
- Division of Biotechnology, Lund University, P.O.Box 124, 221 00, Lund, Sweden
| | | | - Patrick Adlercreutz
- Division of Biotechnology, Lund University, P.O.Box 124, 221 00, Lund, Sweden.
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32
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Espinoza K, Eyzaguirre J. Identification, heterologous expression and characterization of a novel glycoside hydrolase family 30 xylanase from the fungus Penicillium purpurogenum. Carbohydr Res 2018; 468:45-50. [PMID: 30138729 DOI: 10.1016/j.carres.2018.08.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Revised: 08/08/2018] [Accepted: 08/11/2018] [Indexed: 10/28/2022]
Abstract
Penicillium purpurogenum grows on a variety of natural carbon sources and secretes to the medium a large number of enzymes that degrade the polysaccharides present in lignocellulose. In this work, the gene coding for a novel xylanase (XynC) belonging to family 30 of the glycoside hydrolases (GH), has been identified in the genome of the fungus. The enzyme has been expressed in Pichia pastoris and characterized. The mature XynC has 454 amino acid residues and a calculated molecular weight of 49 240. The purified protein shows a molecular weight of 67 000, and it is partially deglycosylated using EndoH. Its pH optimum is in the range of 3-5, and the optimal temperature is 45 °C. It is active on both arabinoxylan and glucuronoxylan, similarly to other fungal GH 30 xylanases. It liberates a set of oligosaccharides, which have been detected by thin-layer chromatography, thus indicating that it is an endo-acting xylanase. It hydrolyzes xylooligosaccharides, releasing mainly xylobiose, in contrast to other fungal GH family 30 enzymes which generate chiefly xylose. Highest sequence identity to a characterized family 30 xylanase is found with the enzyme from the fungus Bispora sp (53%). This is the first GH 30 xylanase described from a Penicillium.
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Affiliation(s)
- Karina Espinoza
- Departamento de Ciencias Biológicas, Universidad Andrés Bello, República 217, Santiago, Chile
| | - Jaime Eyzaguirre
- Departamento de Ciencias Biológicas, Universidad Andrés Bello, República 217, Santiago, Chile.
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33
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Guo Y, Gao Z, Xu J, Chang S, Wu B, He B. A family 30 glucurono-xylanase from Bacillus subtilis LC9: Expression, characterization and its application in Chinese bread making. Int J Biol Macromol 2018; 117:377-384. [PMID: 29792964 DOI: 10.1016/j.ijbiomac.2018.05.143] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Revised: 04/10/2018] [Accepted: 05/21/2018] [Indexed: 11/19/2022]
Abstract
A GH30-8 endoxylanase was identified from an environmental Bacillus subtilis isolate following growth selection on aspen wood glucuronoxylan. The putative endoxylanase was cloned for protein expression and characterization in the Gram-positive protease deficient protein expression host B. subtilis WB800. The extracellular activity obtained was 55 U/mL, which was 14.5-fold higher than that obtained with the native species. The apparent molecular mass of BsXyn30 was estimated as 43 kDa by SDS-PAGE. BsXyn30 showed an optimal activity at pH 7.0 and 60 °C. Recombinant BsXyn30 displayed maximum activity against aspen wood xylan, followed by beechwood xylan but showed no catalytic activity on arabinose-substituted xylans. Analysis of hydrolyzed products of beechwood xylan by thin-layer chromatography and mass spectroscopy revealed the presence of xylooligosaccharides with a single methyl-glucuronic acid residue. BsXyn30 exhibited very low activity for hydrolysis xylotetraose and xylopentaose, but had no detectable activity against xylobiose and xylotriose. Using BsXyn30 as an additive in breadmaking, a decrease in water-holding capacity, an increase in dough expansion as well as improvements in volume and specific volume of the bread were recorded. Thus, the present study provided the basis for the application of GH30 xylanase in breadmaking.
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Affiliation(s)
- Yalan Guo
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, 30 Puzhunan Road, Nanjing 211816, Jiangsu, China
| | - Zhen Gao
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, 30 Puzhunan Road, Nanjing 211816, Jiangsu, China
| | - Jiaxing Xu
- Jiangsu Key Laboratory for Biomass-Based Energy and Enzyme Technology, Huaiyin Normal University, Huaian 223300, Jiangsu, China
| | - Siyuan Chang
- School of Pharmaceutical Sciences, Nanjing Tech University, 30 Puzhunan Road, Nanjing 211816, Jiangsu, China
| | - Bin Wu
- College of Biotechnology and Pharmaceutical Engineering, Nanjing Tech University, 30 Puzhunan Road, Nanjing 211816, Jiangsu, China.
| | - Bingfang He
- School of Pharmaceutical Sciences, Nanjing Tech University, 30 Puzhunan Road, Nanjing 211816, Jiangsu, China
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34
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A plasmid borne, functionally novel glycoside hydrolase family 30 subfamily 8 endoxylanase from solventogenic Clostridium. Biochem J 2018; 475:1533-1551. [PMID: 29626157 PMCID: PMC5934979 DOI: 10.1042/bcj20180050] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2018] [Revised: 03/28/2018] [Accepted: 04/03/2018] [Indexed: 11/24/2022]
Abstract
Glycoside hydrolase family 30 subfamily 8 (GH30-8) β-1,4-endoxylanases are known for their appendage-dependent function requiring recognition of an α-1,2-linked glucuronic acid (GlcA) common to glucuronoxylans for hydrolysis. Structural studies have indicated that the GlcA moiety of glucuronoxylans is coordinated through six hydrogen bonds and a salt bridge. These GlcA-dependent endoxylanases do not have significant activity on xylans that do not bear GlcA substitutions such as unsubstituted linear xylooligosaccharides or cereal bran arabinoxylans. In the present study, we present the structural and biochemical characteristics of xylanase 30A from Clostridium acetobutylicum (CaXyn30A) which was originally selected for study due to predicted structural differences within the GlcA coordination loops. Amino acid sequence comparisons indicated that this Gram-positive-derived GH30-8 more closely resembles Gram-negative derived forms of these endoxylanases: a hypothesis borne out in the developed crystallographic structure model of the CaXyn30A catalytic domain (CaXyn30A-CD). CaXyn30A-CD hydrolyzes xylans to linear and substituted oligoxylosides showing the greatest rate with the highly arabinofuranose (Araf)-substituted cereal arabinoxylans. CaXyn30A-CD hydrolyzes xylooligosaccharides larger than xylotriose and shows an increased relative rate of hydrolysis for xylooligosaccharides containing α-1,2-linked arabinofuranose substitutions. Biochemical analysis confirms that CaXyn30A benefits from five xylose-binding subsites which extend from the −3 subsite to the +2 subsite of the binding cleft. These studies indicate that CaXyn30A is a GlcA-independent endoxylanase that may have evolved for the preferential recognition of α-1,2-Araf substitutions on xylan chains.
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35
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Wei L, Yan T, Wu Y, Chen H, Zhang B. Optimization of alkaline extraction of hemicellulose from sweet sorghum bagasse and its direct application for the production of acidic xylooligosaccharides by Bacillus subtilis strain MR44. PLoS One 2018; 13:e0195616. [PMID: 29634785 PMCID: PMC5892927 DOI: 10.1371/journal.pone.0195616] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2017] [Accepted: 03/25/2018] [Indexed: 11/25/2022] Open
Abstract
As predominant components of hemicelluloses in grasses, methylglucuroarabinoxylans (MeGAXn) are sources for the production of acidic xylooligosaccharides (U-XOS). Bacillus subtilis MR44, an engineered biocatalyst to secrete only the XynC xylanase and Axh43 arabinoxylan hydrolase is capable of processing MeGAXn to exclusively U-XOS. The present studies are directed at the explosion on direct alkaline extraction serving for production of U-XOS. Response Surface Methodology was used to optimize xylan extraction conditions on the sweet sorghum bagasse to achieve maximum hemicelluloses yield. The optimized condition was as follows: extraction time of 3.91 h, extraction temperature of 86.1°C, and NaOH concentration (w/w) of 12.33%. Crude xylan extracted with NaOH revealed a compositional analysis of xylose (79.0%), arabinose (5.3%), glucose (1.7%), lignin and ash (5.6%). After neutralization this xylan preparation supported growth of MR44, processing MeGAXn from sweet sorghum and accumulating U-XOS. The quality of U-XOS produced by MR44 using alkaline-treated sweet sorghum bagasse was comparable to that obtained from purified MeGAXn. Overall, the present study demonstrates that direct alkaline treatment of sweet sorghum bagasse is useful to improve the bioavailability of MeGAXn for MR44-mediated conversion to U-XOS with average degrees of polymerization of 11–12, providing alternative resources with applications in nutrition and human and veterinary medicine.
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Affiliation(s)
- Lusha Wei
- College of Food Engineering and Nutritional Science, Shaanxi Normal University, Xi’an, Shaanxi, China
| | - Tongjing Yan
- College of Food Engineering and Nutritional Science, Shaanxi Normal University, Xi’an, Shaanxi, China
| | - Yifei Wu
- Department of Life Science, Northwest University, Xi’an, Shaanxi, China
| | - Hui Chen
- College of Forestry, Northwest A&F University, Yangling, Shaanxi, China
| | - Baoshan Zhang
- College of Food Engineering and Nutritional Science, Shaanxi Normal University, Xi’an, Shaanxi, China
- * E-mail:
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Šuchová K, Kozmon S, Puchart V, Malovíková A, Hoff T, Mørkeberg Krogh KBR, Biely P. Glucuronoxylan recognition by GH 30 xylanases: A study with enzyme and substrate variants. Arch Biochem Biophys 2018; 643:42-49. [PMID: 29477770 DOI: 10.1016/j.abb.2018.02.014] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Revised: 02/07/2018] [Accepted: 02/19/2018] [Indexed: 10/18/2022]
Abstract
XynA from Erwinia chrysanthemi (EcXyn30A), belonging to glycoside hydrolase family 30 subfamily 8, is specialized for hydrolysis of 4-O-methylglucuronoxylan (GX). Carboxyl group of 4-O-methylglucuronic acid serves as a substrate recognition element interacting ionically with positively charged Arg293 of the enzyme. We determined kinetic parameters of EcXyn30A on GX, its methyl ester (GXE) and 4-O-methylglucoxylan (GXR) and compared them with behavior of the enzyme variant in which Arg293 was replaced by Ala. The modifications of the substrate carboxyl groups resulted in several thousand-fold decrease in catalytic efficiency of EcXyn30A. In contrast, the R293A replacement reduced catalytic efficiency on GX only 18-times. The main difference was in catalytic rate (kcat) which was much lower for EcXyn30A acting on the modified substrates than for the variant which exhibited similar kcat values on all three polymers. The R293A variant cleaved GX, GXE and GXR on the second glycosidic bond from branch towards the reducing end, similarly to EcXyn30A. The R293A replacement caused 15-times decrease in specific activity on MeGlcA3Xyl4, but it did not influence low activity on linear xylooligosaccharides. Docking experiments showed that MeGlcA3Xyl4 and its esterified and reduced forms were bound to both enzymes in analogous way but with different binding energies.
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Affiliation(s)
- Katarína Šuchová
- Institute of Chemistry, Slovak Academy of Sciences, Bratislava, Slovakia.
| | - Stanislav Kozmon
- Institute of Chemistry, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Vladimír Puchart
- Institute of Chemistry, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Anna Malovíková
- Institute of Chemistry, Slovak Academy of Sciences, Bratislava, Slovakia
| | | | | | - Peter Biely
- Institute of Chemistry, Slovak Academy of Sciences, Bratislava, Slovakia
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Aronsson A, Güler F, Petoukhov MV, Crennell SJ, Svergun DI, Linares-Pastén JA, Nordberg Karlsson E. Structural insights of Rm Xyn10A – A prebiotic-producing GH10 xylanase with a non-conserved aglycone binding region. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2018; 1866:292-306. [DOI: 10.1016/j.bbapap.2017.11.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Revised: 10/05/2017] [Accepted: 11/12/2017] [Indexed: 02/02/2023]
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GH30 Glucuronoxylan-Specific Xylanase from Streptomyces turgidiscabies C56. Appl Environ Microbiol 2018; 84:AEM.01850-17. [PMID: 29180367 DOI: 10.1128/aem.01850-17] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2017] [Accepted: 11/16/2017] [Indexed: 11/20/2022] Open
Abstract
Endoxylanases are important enzymes in bioenergy research because they specifically hydrolyze xylan, the predominant polysaccharide in the hemicellulose fraction of lignocellulosic biomass. For effective biomass utilization, it is important to understand the mechanism of substrate recognition by these enzymes. Recent studies have shown that the substrate specificities of bacterial and fungal endoxylanases classified into glycoside hydrolase family 30 (GH30) were quite different. While the functional differences have been described, the mechanism of substrate recognition is still unknown. Therefore, a gene encoding a putative GH30 endoxylanase was cloned from Streptomyces turgidiscabies C56, and the recombinant enzyme was purified and characterized. GH30 glucuronoxylan-specific xylanase A of Streptomyces turgidiscabies (StXyn30A) showed hydrolytic activity with xylans containing both glucuronic acid and the more common 4-O-methyl-glucuronic acid side-chain substitutions but not on linear xylooligosaccharides, suggesting that this enzyme requires the recognition of glucuronic acid side chains for hydrolysis. The StXyn30A limit product structure was analyzed following a secondary β-xylosidase treatment by thin-layer chromatography and mass spectrometry analysis. The hydrolysis products from both glucuronoxylan and 4-O-methylglucuronoxylan by StXyn30A have these main-chain substitutions on the second xylopyranosyl residue from the reducing end. Because previous structural studies of bacterial GH30 enzymes and molecular modeling of StXyn30A suggested that a conserved arginine residue (Arg296) interacts with the glucuronic acid side-chain carboxyl group, we focused on this residue, which is conserved at subsite -2 of bacterial but not fungal GH30 endoxylanases. To help gain an understanding of the mechanism of how StXyn30A recognizes glucuronic acid substitutions, Arg296 mutant enzymes were studied. The glucuronoxylan hydrolytic activities of Arg296 mutants were significantly reduced in comparison to those of the wild-type enzyme. Furthermore, limit products other than aldotriouronic acid were observed for these Arg296 mutants upon secondary β-xylosidase treatment. These results indicate that a disruption of the highly conserved Arg296 interaction leads to a decrease of functional specificity in StXyn30A, as indicated by the detection of alternative hydrolysis products. Our studies allow a better understanding of the mechanism of glucuronoxylan recognition and enzyme specificity by bacterial GH30 endoxylanases and provide further definition of these unique enzymes for their potential application in industry.IMPORTANCE Hemicellulases are important enzymes that hydrolyze hemicellulosic polysaccharides to smaller sugars for eventual microbial assimilation and metabolism. These hemicellulases include endoxylanases that cleave the β-1,4-xylose main chain of xylan, the predominant form of hemicellulose in lignocellulosic biomass. Endoxylanases play an important role in the utilization of plant biomass because in addition to their general utility in xylan degradation, they can also be used to create defined compositions of xylooligosaccharides. For this, it is important to understand the mechanism of substrate recognition. Recent studies have shown that the substrate specificities of bacterial and fungal endoxylanases that are classified into glycoside hydrolase family 30 (GH30) were distinct, but the difference in the mechanisms of substrate recognition is still unknown. We performed characterization and mutagenesis analyses of a new bacterial GH30 endoxylanase for comparison with previously reported fungal GH30 endoxylanases. Our study results in a better understanding of the mechanism of substrate specificity and recognition for bacterial GH30 endoxylanases. The experimental approach and resulting data support the conclusions and provide further definition of the structure and function of GH30 endoxylanases for their application in bioenergy research.
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Linares-Pastén JA, Aronsson A, Karlsson EN. Structural Considerations on the Use of Endo-Xylanases for the Production of prebiotic Xylooligosaccharides from Biomass. Curr Protein Pept Sci 2018; 19:48-67. [PMID: 27670134 PMCID: PMC5738707 DOI: 10.2174/1389203717666160923155209] [Citation(s) in RCA: 40] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Revised: 08/31/2016] [Accepted: 09/15/2016] [Indexed: 11/24/2022]
Abstract
Xylooligosaccharides (XOS) have gained increased interest as prebiotics during the last years. XOS and arabinoxylooligosaccharides (AXOS) can be produced from major fractions of biomass including agricultural by-products and other low cost raw materials. Endo-xylanases are key enzymes for the production of (A)XOS from xylan. As the xylan structure is broadly diverse due to different substitutions, diverse endo-xylanases have evolved for its degradation. In this review structural and functional aspects are discussed, focusing on the potential applications of endo-xylanases in the production of differently substituted (A)XOS as emerging prebiotics, as well as their implication in the processing of the raw materials. Endo-xylanases are found in at least eight different glycoside hydrolase families (GH), and can either have a retaining or an inverting catalytic mechanism. To date, it is mainly retaining endo-xylanases that are used in applications to produce (A)XOS. Enzymes from these GH-families (mainly GH10 and GH11, and the more recently investigated GH30) are taken as prototypes to discuss substrate preferences and main products obtained. Finally, the need of new and accessory enzymes (new specificities from new families or sources) to increase the yield of different types of (A)XOS is discussed, along with in vitro tests of produced oligosaccharides and production of enzymes in GRAS organisms to facilitate use in functional food manufacturing.
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Affiliation(s)
| | - Anna Aronsson
- Biotechnology, Department of Chemistry, Lund University, Lund, Sweden
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40
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Salunke DM, Nair DT. Macromolecular structures: Quality assessment and biological interpretation. IUBMB Life 2017; 69:563-571. [DOI: 10.1002/iub.1640] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2017] [Accepted: 04/25/2017] [Indexed: 02/05/2023]
Affiliation(s)
- Dinakar M. Salunke
- International Centre for Genetic Engineering and Biotechnology; Aruna Asaf Ali Marg; New Delhi India
| | - Deepak T. Nair
- Regional Centre for Biotechnology, NCR Biotech Science Cluster; 3rd Milestone, Faridabad-Gurgaon Expressway Faridabad Haryana India
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Xylanase 30 A from Clostridium thermocellum functions as a glucuronoxylan xylanohydrolase. ACTA ACUST UNITED AC 2016. [DOI: 10.1016/j.molcatb.2017.03.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Freire F, Verma A, Bule P, Alves VD, Fontes CMGA, Goyal A, Najmudin S. Conservation in the mechanism of glucuronoxylan hydrolysis revealed by the structure of glucuronoxylan xylanohydrolase (CtXyn30A) from Clostridium thermocellum. ACTA CRYSTALLOGRAPHICA SECTION D-STRUCTURAL BIOLOGY 2016; 72:1162-1173. [PMID: 27841749 DOI: 10.1107/s2059798316014376] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2016] [Accepted: 09/09/2016] [Indexed: 11/10/2022]
Abstract
Glucuronoxylan endo-β-1,4-xylanases cleave the xylan chain specifically at sites containing 4-O-methylglucuronic acid substitutions. These enzymes have recently received considerable attention owing to their importance in the cooperative hydrolysis of heteropolysaccharides. However, little is known about the hydrolysis of glucuronoxylans in extreme environments. Here, the structure of a thermostable family 30 glucuronoxylan endo-β-1,4-xylanase (CtXyn30A) from Clostridium thermocellum is reported. CtXyn30A is part of the cellulosome, a highly elaborate multi-enzyme complex secreted by the bacterium to efficiently deconstruct plant cell-wall carbohydrates. CtXyn30A preferably hydrolyses glucuronoxylans and displays maximum activity at pH 6.0 and 70°C. The structure of CtXyn30A displays a (β/α)8 TIM-barrel core with a side-associated β-sheet domain. Structural analysis of the CtXyn30A mutant E225A, solved in the presence of xylotetraose, revealed xylotetraose-cleavage oligosaccharides partially occupying subsites -3 to +2. The sugar ring at the +1 subsite is held in place by hydrophobic stacking interactions between Tyr139 and Tyr200 and hydrogen bonds to the OH group of Tyr227. Although family 30 glycoside hydrolases are retaining enzymes, the xylopyranosyl ring at the -1 subsite of CtXyn30A-E225A appears in the α-anomeric configuration. A set of residues were found to be strictly conserved in glucuronoxylan endo-β-1,4-xylanases and constitute the molecular determinants of the restricted specificity displayed by these enzymes. CtXyn30A is the first thermostable glucuronoxylan endo-β-1,4-xylanase described to date. This work reveals that substrate recognition by both thermophilic and mesophilic glucuronoxylan endo-β-1,4-xylanases is modulated by a conserved set of residues.
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Affiliation(s)
- Filipe Freire
- CIISA-Faculdade de Medicina Veterinária, Universidade de Lisboa, Avenida da Universidade Técnica, 1300-477 Lisboa, Portugal
| | - Anil Verma
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati 781 039, India
| | - Pedro Bule
- CIISA-Faculdade de Medicina Veterinária, Universidade de Lisboa, Avenida da Universidade Técnica, 1300-477 Lisboa, Portugal
| | - Victor D Alves
- CIISA-Faculdade de Medicina Veterinária, Universidade de Lisboa, Avenida da Universidade Técnica, 1300-477 Lisboa, Portugal
| | - Carlos M G A Fontes
- CIISA-Faculdade de Medicina Veterinária, Universidade de Lisboa, Avenida da Universidade Técnica, 1300-477 Lisboa, Portugal
| | - Arun Goyal
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati 781 039, India
| | - Shabir Najmudin
- CIISA-Faculdade de Medicina Veterinária, Universidade de Lisboa, Avenida da Universidade Técnica, 1300-477 Lisboa, Portugal
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A novel member of family 30 glycoside hydrolase subfamily 8 glucuronoxylan endo-β-1,4-xylanase (CtXynGH30) from Clostridium thermocellum orchestrates catalysis on arabinose decorated xylans. ACTA ACUST UNITED AC 2016. [DOI: 10.1016/j.molcatb.2016.04.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Salunke DM, Khan T, Gaur V, Tapryal S, Kaur K. Response to Comment on Three X-ray Crystal Structure Papers. THE JOURNAL OF IMMUNOLOGY 2016; 196:524-8. [PMID: 26747566 DOI: 10.4049/jimmunol.1501474] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Affiliation(s)
| | - Tarique Khan
- Department of Biochemistry, UT Southwestern Medical Center, Dallas, TX 75390
| | - Vineet Gaur
- International Institute of Molecular and Cell Biology; Warsaw 02-109, Poland
| | - Suman Tapryal
- Department of Biotechnology, Central University of Rajasthan, Bandarsindri-305817, India; and
| | - Kanwaljeet Kaur
- National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi-110067, India
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Xylan decoration patterns and the plant secondary cell wall molecular architecture. Biochem Soc Trans 2016; 44:74-8. [DOI: 10.1042/bst20150183] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The molecular architecture of plant secondary cell walls is still not resolved. There are several proposed structures for cellulose fibrils, the main component of plant cell walls and the conformation of other molecules is even less well known. Glucuronic acid (GlcA) substitution of xylan (GUX) enzymes, in CAZy family glycosyl transferase (GT)8, decorate the xylan backbone with various specific patterns of GlcA. It was recently discovered that dicot xylan has a domain with the side chain decorations distributed on every second unit of the backbone (xylose). If the xylan backbone folds in a similar way to glucan chains in cellulose (2-fold helix), this kind of arrangement may allow the undecorated side of the xylan chain to hydrogen bond with the hydrophilic surface of cellulose microfibrils. MD simulations suggest that such interactions are energetically stable. We discuss the possible role of this xylan decoration pattern in building of the plant cell wall.
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McKee LS, Sunner H, Anasontzis GE, Toriz G, Gatenholm P, Bulone V, Vilaplana F, Olsson L. A GH115 α-glucuronidase from Schizophyllum commune contributes to the synergistic enzymatic deconstruction of softwood glucuronoarabinoxylan. BIOTECHNOLOGY FOR BIOFUELS 2016; 9:2. [PMID: 26734072 PMCID: PMC4700659 DOI: 10.1186/s13068-015-0417-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Accepted: 12/15/2015] [Indexed: 05/11/2023]
Abstract
BACKGROUND Lignocellulosic biomass from softwood represents a valuable resource for the production of biofuels and bio-based materials as alternatives to traditional pulp and paper products. Hemicelluloses constitute an extremely heterogeneous fraction of the plant cell wall, as their molecular structures involve multiple monosaccharide components, glycosidic linkages, and decoration patterns. The complete enzymatic hydrolysis of wood hemicelluloses into monosaccharides is therefore a complex biochemical process that requires the activities of multiple degradative enzymes with complementary activities tailored to the structural features of a particular substrate. Glucuronoarabinoxylan (GAX) is a major hemicellulose component in softwood, and its structural complexity requires more enzyme specificities to achieve complete hydrolysis compared to glucuronoxylans from hardwood and arabinoxylans from grasses. RESULTS We report the characterisation of a recombinant α-glucuronidase (Agu115) from Schizophyllum commune capable of removing (4-O-methyl)-glucuronic acid ((Me)GlcA) residues from polymeric and oligomeric xylan. The enzyme is required for the complete deconstruction of spruce glucuronoarabinoxylan (GAX) and acts synergistically with other xylan-degrading enzymes, specifically a xylanase (Xyn10C), an α-l-arabinofuranosidase (AbfA), and a β-xylosidase (XynB). Each enzyme in this mixture showed varying degrees of potentiation by the other activities, likely due to increased physical access to their respective target monosaccharides. The exo-acting Agu115 and AbfA were unable to remove all of their respective target side chain decorations from GAX, but their specific activity was significantly boosted by the addition of the endo-Xyn10C xylanase. We demonstrate that the proposed enzymatic cocktail (Agu115 with AbfA, Xyn10C and XynB) achieved almost complete conversion of GAX to arabinofuranose (Araf), xylopyranose (Xylp), and MeGlcA monosaccharides. Addition of Agu115 to the enzymatic cocktail contributes specifically to 25 % of the conversion. However, traces of residual oligosaccharides resistant to this combination of enzymes were still present after deconstruction, due to steric hindrances to enzyme access to the substrate. CONCLUSIONS Our GH115 α-glucuronidase is capable of finely tailoring the molecular structure of softwood GAX, and contributes to the almost complete saccharification of GAX in synergy with other exo- and endo-xylan-acting enzymes. This has great relevance for the cost-efficient production of biofuels from softwood lignocellulose.
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Affiliation(s)
- Lauren S. McKee
- />Wallenberg Wood Science Centre, Division of Glycoscience, School of Biotechnology, KTH Royal Institute of Technology, AlbaNova University Centre, 106 91 Stockholm, Sweden
| | - Hampus Sunner
- />Wallenberg Wood Science Centre, Division of Industrial Biotechnology, Department of Biology and Biological Engineering, Chalmers University of Technology, 412 96 Gothenburg, Sweden
| | - George E. Anasontzis
- />Wallenberg Wood Science Centre, Division of Industrial Biotechnology, Department of Biology and Biological Engineering, Chalmers University of Technology, 412 96 Gothenburg, Sweden
| | - Guillermo Toriz
- />Wallenberg Wood Science Centre, Department of Chemistry and Chemical Engineering, Chalmers University of Technology, 412 96 Gothenburg, Sweden
- />Department of Wood, Cellulose and Paper Research, University of Guadalajara, Guadalajara, Mexico
| | - Paul Gatenholm
- />Wallenberg Wood Science Centre, Department of Chemistry and Chemical Engineering, Chalmers University of Technology, 412 96 Gothenburg, Sweden
| | - Vincent Bulone
- />Wallenberg Wood Science Centre, Division of Glycoscience, School of Biotechnology, KTH Royal Institute of Technology, AlbaNova University Centre, 106 91 Stockholm, Sweden
- />ARC Centre of Excellence in Plant Cell Walls and School of Agriculture, Food and Wine, The University of Adelaide, Waite Campus, Urrbrae, SA 5064 Australia
| | - Francisco Vilaplana
- />Wallenberg Wood Science Centre, Division of Glycoscience, School of Biotechnology, KTH Royal Institute of Technology, AlbaNova University Centre, 106 91 Stockholm, Sweden
| | - Lisbeth Olsson
- />Wallenberg Wood Science Centre, Division of Industrial Biotechnology, Department of Biology and Biological Engineering, Chalmers University of Technology, 412 96 Gothenburg, Sweden
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Valls A, Diaz P, Pastor FIJ, Valenzuela SV. A newly discovered arabinoxylan-specific arabinofuranohydrolase. Synergistic action with xylanases from different glycosyl hydrolase families. Appl Microbiol Biotechnol 2015; 100:1743-1751. [DOI: 10.1007/s00253-015-7061-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Revised: 09/27/2015] [Accepted: 10/05/2015] [Indexed: 01/11/2023]
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48
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The role of the glucuronoxylan carboxyl groups in the action of endoxylanases of three glycoside hydrolase families: A study with two substrate mutants. Biochim Biophys Acta Gen Subj 2015; 1850:2246-55. [PMID: 26172579 DOI: 10.1016/j.bbagen.2015.07.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Revised: 07/02/2015] [Accepted: 07/10/2015] [Indexed: 11/21/2022]
Abstract
BACKGROUND Bacterial appendage-dependent GH30 glucuronoxylan hydrolases recognize the substrate through an ionic interaction of a conserved positively charged arginine with the carboxyl group of 4-O-methyl-d-glucuronic acid. One of the options to verify this interaction is preparation of enzyme mutants. An alternative approach is a chemical modification of the substrate, glucuronoxylan, in which the free carboxyl group in all residues of MeGlcA is eliminated. METHODS In this work the carboxyl groups of 4-O-methyl-d-glucuronic acid residues of an alkali extracted beechwood xylan were esterified with methanol. A water-soluble fraction of the polysaccharide methyl ester was converted by NaBH4 reduction to the second soluble derivative, 4-O-methylglucoxylan. Specific activities of several endoxylanases (EXs) of GH families 10, 11 and 30 were determined on glucuronoxylan, and its two new uncharged derivatives. RESULTS Elimination of the free carboxyl group from the polysaccharide did not influence activities of GH10 EXs, but resulted in 50% decrease of specific activity of GH11 EXs, and led to more than 300-fold reduction of specific activity of Erwinia chrysanthemi GH30 xylanase. CONCLUSIONS These results confirm the crucial role of the interactions between GH30 xylanases and the MeGlcA carboxyl group for efficient cleavage of the polysaccharide. Analysis of the hydrolysis products by TLC and MS confirmed that all three types of xylanases hydrolyzed uncharged glucuronoxylans similarly as the original one. SIGNIFICANCE The uncharged glucuronoxylan derivatives will be useful to differentiate GH30 xylanases with various degree of selectivity for glucuronoxylan, including fungal enzymes without the conserved arginine.
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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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50
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St John FJ, Dietrich D, Crooks C, Pozharski E, González JM, Bales E, Smith K, Hurlbert JC. A novel member of glycoside hydrolase family 30 subfamily 8 with altered substrate specificity. ACTA CRYSTALLOGRAPHICA. SECTION D, BIOLOGICAL CRYSTALLOGRAPHY 2014; 70:2950-8. [PMID: 25372685 PMCID: PMC4722856 DOI: 10.1107/s1399004714019531] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2014] [Accepted: 08/28/2014] [Indexed: 11/10/2022]
Abstract
Endoxylanases classified into glycoside hydrolase family 30 subfamily 8 (GH30-8) are known to hydrolyze the hemicellulosic polysaccharide glucuronoxylan (GX) but not arabinoxylan or neutral xylooligosaccharides. This is owing to the specificity of these enzymes for the α-1,2-linked glucuronate (GA) appendage of GX. Limit hydrolysis of this substrate produces a series of aldouronates each containing a single GA substituted on the xylose penultimate to the reducing terminus. In this work, the structural and biochemical characterization of xylanase 30A from Clostridium papyrosolvens (CpXyn30A) is presented. This xylanase possesses a high degree of amino-acid identity to the canonical GH30-8 enzymes, but lacks the hallmark β8-α8 loop region which in part defines the function of this GH30 subfamily and its role in GA recognition. CpXyn30A is shown to have a similarly low activity on all xylan substrates, while hydrolysis of xylohexaose revealed a competing transglycosylation reaction. These findings are directly compared with the model GH30-8 enzyme from Bacillus subtilis, XynC. Despite its high sequence identity to the GH30-8 enzymes, CpXyn30A does not have any apparent specificity for the GA appendage. These findings confirm that the typically conserved β8-α8 loop region of these enzymes influences xylan substrate specificity but not necessarily β-1,4-xylanase function.
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Affiliation(s)
- Franz J. St John
- Forest Products Laboratory, USDA Forest Service, Madison, Wisconsin, USA
| | - Diane Dietrich
- Forest Products Laboratory, USDA Forest Service, Madison, Wisconsin, USA
| | - Casey Crooks
- Forest Products Laboratory, USDA Forest Service, Madison, Wisconsin, USA
| | - Edwin Pozharski
- Department of Biochemistry and Molecular Biology, University of Maryland, Maryland, USA
| | - Javier M. González
- Bioscience Division, Los Alamos National Laboratory, Los Alamos, New Mexico, USA
| | - Elizabeth Bales
- Department of Chemistry, Physics and Geology, Winthrop University, Rock Hill, South Carolina, USA
| | - Kennon Smith
- Department of Chemistry, Physics and Geology, Winthrop University, Rock Hill, South Carolina, USA
| | - Jason C. Hurlbert
- Department of Chemistry, Physics and Geology, Winthrop University, Rock Hill, South Carolina, USA
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