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Chen Z, Mense AL, Brewer LR, Shi YC. Wheat bran arabinoxylans: Chemical structure, extraction, properties, health benefits, and uses in foods. Compr Rev Food Sci Food Saf 2024; 23:e13366. [PMID: 38775125 DOI: 10.1111/1541-4337.13366] [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: 10/25/2023] [Revised: 04/10/2024] [Accepted: 04/25/2024] [Indexed: 07/02/2024]
Abstract
Wheat bran (WB) is a well-known and valuable source of dietary fiber. Arabinoxylan (AX) is the primary hemicellulose in WB and can be isolated and used as a functional component in various food products. Typically, AX is extracted from the whole WB using different processes after mechanical treatments. However, WB is composed of different layers, namely, the aleurone layer, pericarp, testa, and hyaline layer. The distribution, structure, and extractability of AX vary within these layers. Modern fractionation technologies, such as debranning and electrostatic separation, can separate the different layers of WB, making it possible to extract AX from each layer separately. Therefore, AX in WB shows potential for broader applications if it can be extracted from the different layers separately. In this review, the distribution and chemical structures of AX in WB layers are first discussed followed by extraction, physicochemical properties, and health benefits of isolated AX from WB. Additionally, the utilization of AX isolated from WB in foods, including cereal foods, packaging film, and the delivery of food ingredients, is reviewed. Future perspectives on challenges and opportunities in the research field of AX isolated from WB are highlighted.
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Affiliation(s)
- Zhongwei Chen
- School of Food and Biological Engineering, Jiangsu University, Zhenjiang, Jiangsu Province, P. R. China
- Department of Grain Science and Industry, Kansas State University, Manhattan, Kansas, USA
| | - Andrew L Mense
- Department of Grain Science and Industry, Kansas State University, Manhattan, Kansas, USA
- Wheat Marketing Center, Portland, Oregon, USA
| | - Lauren R Brewer
- Department of Grain Science and Industry, Kansas State University, Manhattan, Kansas, USA
| | - Yong-Cheng Shi
- Department of Grain Science and Industry, Kansas State University, Manhattan, Kansas, USA
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2
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Pentari C, Zerva A, Kosinas C, Karampa P, Puchart V, Dimarogona M, Topakas E. The role of CE16 exo-deacetylases in hemicellulolytic enzyme mixtures revealed by the biochemical and structural study of the novel TtCE16B esterase. Carbohydr Polym 2024; 327:121667. [PMID: 38171682 DOI: 10.1016/j.carbpol.2023.121667] [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: 08/24/2023] [Revised: 12/03/2023] [Accepted: 12/04/2023] [Indexed: 01/05/2024]
Abstract
Acetyl esterases belonging to the carbohydrate esterase family 16 (CE16) is a growing group of enzymes, with exceptional diversity regarding substrate specificity and regioselectivity. However, further insight into the CE16 specificity is required for their efficient biotechnological exploitation. In this work, exo-deacetylase TtCE16B from Thermothelomyces thermophila was heterologously expressed and biochemically characterized. The esterase targets positions O-3 and O-4 of singly and doubly acetylated non-reducing-end xylopyranosyl residues, provided the presence of a free vicinal hydroxyl group at position O-4 and O-3, respectively. Crystal structure of TtCE16B, the first representative among the CE16 enzymes, in apo- and product-bound form, allowed the identification of residues forming the catalytic triad and oxyanion hole, as well as the structural elements related to the enzyme preference for oligomers. The role of TtCE16B in hemicellulose degradation was investigated on acetylated xylan from birchwood and pre-treated beechwood biomass. TtCE16B exhibited complementary activity to commercially available OCE6 acetylxylan esterase. Moreover, it showed synergistic effects with SrXyl43 β-xylosidase. Overall, supplementation of xylan-targeting enzymatic mixtures with both TtCE16B and OCE6 esterases led to a 3-fold or 4-fold increase in xylose release, when using TmXyn10 and TtXyn30A xylanases respectively.
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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
| | - Anastasia Zerva
- Industrial Biotechnology & Biocatalysis Group, Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens, Athens, Greece; Laboratory of Enzyme Technology, Department of Biotechnology, School of Applied Biology and Biotechnology, Agricultural University of Athens, 75 Iera Odos Street, 11855 Athens, Greece
| | - Christos Kosinas
- Laboratory of Structural Biology and Biotechnology, Department of Chemical Engineering, University of Patras, Patras, Greece
| | - Panagiota Karampa
- Laboratory of Structural Biology and Biotechnology, Department of Chemical Engineering, University of Patras, Patras, Greece
| | - Vladimír Puchart
- Institute of Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, 845 38 Bratislava, Slovak Republic
| | - 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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Lan X, Fu S, Song J, Leu S, Shen J, Kong Y, Kang S, Yuan X, Liu H. Structural changes of hemicellulose during pulping process and its interaction with nanocellulose. Int J Biol Macromol 2024; 255:127772. [PMID: 37913887 DOI: 10.1016/j.ijbiomac.2023.127772] [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: 07/03/2023] [Revised: 09/06/2023] [Accepted: 10/27/2023] [Indexed: 11/03/2023]
Abstract
It is believed that hemicellulose plays a crucial role in binding cellulose and lignin in plant cells. It may provide significant implications through figuring out the interaction between hemicellulose and microfibers and gaining insights how the structure of hemicellulose affects its association with cellulose nanofibers. Herein, the hemicellulose and nanocellulose fractions from pulps obtained by controlling the H-factors of kraft pulping process were quantitatively evaluated for their adsorption behavior using QCM-D. The results showed that harsher cooking (corresponding to high H-factor) significantly affected the chemical composition of hemicellulose, leading to a decrease of its molecular weight and gradually turning it into a linear structure. Hemicellulose possesses a strong natural affinity for CNC-coated sensors. The hemicellulose from the pulp cooked by high H-factor process decreases its ability to adsorb onto nanocellulose, the adsorption rate also slows down, and the conformation of the adsorbed layer changes which makes the binding weak and reversible. In conclusion, the pulping process in high H-factor significantly changed the structure of hemicellulose, leading to a variation in the strength of its interaction with nanocellulose.
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Affiliation(s)
- Xingyu Lan
- State Key Laboratory of Pulp & Paper Engineering, South China University of Technology, Guangzhou 510640, China
| | - Shiyu Fu
- State Key Laboratory of Pulp & Paper Engineering, South China University of Technology, Guangzhou 510640, China.
| | - Junlong Song
- Joint International Research Lab of Lignocellulosic Functional Materials, International Innovation Center for Forest Chemicals and Materials, Nanjing Forestry University, Nanjing 210037, China
| | - Shaoyuan Leu
- Department of Civil and Environmental Engineering, Hong Kong Polytechnic University, Hung Hom, Hong Kong
| | - Juanli Shen
- State Key Laboratory of Pulp & Paper Engineering, South China University of Technology, Guangzhou 510640, China
| | - Yi Kong
- State Key Laboratory of Pulp & Paper Engineering, South China University of Technology, Guangzhou 510640, China
| | - Shaomin Kang
- Joint International Research Lab of Lignocellulosic Functional Materials, International Innovation Center for Forest Chemicals and Materials, Nanjing Forestry University, Nanjing 210037, China
| | - Xi Yuan
- State Key Laboratory of Pulp & Paper Engineering, South China University of Technology, Guangzhou 510640, China
| | - Hao Liu
- State Key Laboratory of Pulp & Paper Engineering, South China University of Technology, Guangzhou 510640, China
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Pentari C, Zerva A, Dimarogona M, Topakas E. The xylobiohydrolase activity of a GH30 xylanase on natively acetylated xylan may hold the key for the degradation of recalcitrant xylan. Carbohydr Polym 2023; 305:120527. [PMID: 36737185 DOI: 10.1016/j.carbpol.2022.120527] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2022] [Revised: 12/22/2022] [Accepted: 12/29/2022] [Indexed: 01/11/2023]
Abstract
Acetyl substitutions are common on the hemicellulosic structures of lignocellulose, which up until recently were known to inhibit xylanase activity. Emerging data, however, suggest that xylanases are able to accommodate acetyl side-groups within their catalytic site. In the present work, a fungal GH30 xylanase from Thermothelomyces thermophila, namely TtXyn30A, was shown to release acetylated xylobiose when acting on pretreated lignocellulosic substrate. The released disaccharides could be acetylated at the 2-OH, 3-OH or both positions of the non-reducing end xylose, but the existence of the acetylation on the reducing end cannot be excluded. The synergy of TtXyn30A with acetyl esterases indicates that particular subsites within its active site cannot tolerate acetylated xylopyranose residues. Molecular docking showed that acetyl group can be accommodated on the 2- or 3-OH position of the non-reducing end xylose, unlike the reducing-end xylose (subsite -1), where only 3-OH decoration can be accommodated. Such insight into the catalytic activity of TtXyn30A could contribute to a better understanding of its biological role and thus lead to a more sufficient biotechnological utilization.
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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
| | - Anastasia Zerva
- 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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5
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Sasamoto K, Himiyama T, Moriyoshi K, Ohmoto T, Uegaki K, Nakamura T, Nishiya Y. Functional analysis of the N-terminal region of acetylxylan esterase from Caldanaerobacter subterraneus subsp. tengcongensis. FEBS Open Bio 2022; 12:1875-1885. [PMID: 36054591 PMCID: PMC9527590 DOI: 10.1002/2211-5463.13476] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 08/09/2022] [Accepted: 08/22/2022] [Indexed: 12/14/2022] Open
Abstract
Acetylxylan esterase from Caldanaerobacter subterraneus subsp. tengcongensis (TTE0866) has an N-terminal region (NTR; residues 23-135) between the signal sequence (residues 1-22) and the catalytic domain (residues 136-324), which is of unknown function. Our previous study revealed the crystal structure of the wild-type (WT) enzyme containing the NTR and the catalytic domain. Although the structure of the catalytic domain was successfully determined, that of the NTR was undetermined, as its electron density was unclear. In this study, we investigated the role of the NTR through functional and structural analyses of NTR truncation mutants. Based on sequence and secondary structure analyses, NTR was confirmed to be an intrinsically disordered region. The truncation of NTR significantly decreased the solubility of the proteins at low salt concentrations compared with that of the WT. The NTR-truncated mutant easily crystallized in a conventional buffer solution. The crystal exhibited crystallographic properties comparable with those of the WT crystals suitable for structural determination. These results suggest that NTR plays a role in maintaining the solubility and inhibiting the crystallization of the catalytic domain.
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Affiliation(s)
- Kohei Sasamoto
- Division of Life Science, Graduate School of Science and EngineeringSetsunan UniversityOsakaJapan,Biomedical Research InstituteNational Institute of Advanced Industrial Science and TechnologyOsakaJapan
| | - Tomoki Himiyama
- Biomedical Research InstituteNational Institute of Advanced Industrial Science and TechnologyOsakaJapan
| | | | - Takashi Ohmoto
- Osaka Research Institute of Industrial Science and TechnologyJapan
| | - Koichi Uegaki
- Department of Applied Biological Chemistry, Faculty of AgricultureKindai UniversityNaraJapan,Agricultural Technology and Innovation Research InstituteKindai UniversityNaraJapan
| | - Tsutomu Nakamura
- Biomedical Research InstituteNational Institute of Advanced Industrial Science and TechnologyOsakaJapan
| | - Yoshiaki Nishiya
- Division of Life Science, Graduate School of Science and EngineeringSetsunan UniversityOsakaJapan
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Kojima K, Sunagawa N, Yoshimi Y, Tryfona T, Samejima M, Dupree P, Igarashi K. Acetylated xylan degradation by glycoside hydrolase family 10 and 11 xylanases from the white-rot fungus <i>Phanerochaete chrysosporium</i>. J Appl Glycosci (1999) 2022; 69:35-43. [PMID: 35891899 PMCID: PMC9276525 DOI: 10.5458/jag.jag.jag-2021_0017] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Accepted: 02/28/2022] [Indexed: 11/22/2022] Open
Abstract
Endo-type xylanases are key enzymes in microbial xylanolytic systems, and xylanases belonging to glycoside hydrolase (GH) families 10 or 11 are the major enzymes degrading xylan in nature. These enzymes have typically been characterized using xylan prepared by alkaline extraction, which removes acetyl sidechains from the substrate, and thus the effect of acetyl groups on xylan degradation remains unclear. Here, we compare the ability of GH10 and 11 xylanases, PcXyn10A and PcXyn11B, from the white-rot basidiomycete Phanerochaete chrysosporium to degrade acetylated and deacetylated xylan from various plants. Product quantification revealed that PcXyn10A effectively degraded both acetylated xylan extracted from Arabidopsis thaliana and the deacetylated xylan obtained by alkaline treatment, generating xylooligosaccharides. In contrast, PcXyn11B showed limited activity towards acetyl xylan, but showed significantly increased activity after deacetylation of the xylan. Polysaccharide analysis using carbohydrate gel electrophoresis showed that PcXyn11B generated a broad range of products from native acetylated xylans extracted from birch wood and rice straw, including large residual xylooligosaccharides, while non-acetylated xylan from Japanese cedar was readily degraded into xylooligosaccharides. These results suggest that the degradability of native xylan by GH11 xylanases is highly dependent on the extent of acetyl group substitution. Analysis of 31 fungal genomes in the Carbohydrate-Active enZymes database indicated that the presence of GH11 xylanases is correlated to that of carbohydrate esterase (CE) family 1 acetyl xylan esterases (AXEs), while this is not the case for GH10 xylanases. These findings may imply co-evolution of GH11 xylanases and CE1 AXEs.
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Affiliation(s)
- Keisuke Kojima
- Department of Biomaterial Sciences, The University of Tokyo
| | - Naoki Sunagawa
- Department of Biomaterial Sciences, The University of Tokyo
| | | | | | | | - Paul Dupree
- Department of Biochemistry, University of Cambridge
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7
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Kojima K, Sunagawa N, Mikkelsen NE, Hansson H, Karkehabadi S, Samejima M, Sandgren M, Igarashi K. Comparison of Glycoside Hydrolase family 3 β-xylosidases from basidiomycetes and ascomycetes reveals evolutionarily distinct xylan degradation systems. J Biol Chem 2022; 298:101670. [PMID: 35120929 PMCID: PMC8913315 DOI: 10.1016/j.jbc.2022.101670] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 01/27/2022] [Accepted: 01/28/2022] [Indexed: 11/28/2022] Open
Abstract
Xylan is the most common hemicellulose in plant cell walls, though the structure of xylan polymers differs between plant species. Here, to gain a better understanding of fungal xylan degradation systems, which can enhance enzymatic saccharification of plant cell walls in industrial processes, we conducted a comparative study of two glycoside hydrolase family 3 (GH3) β-xylosidases (Bxls), one from the basidiomycete Phanerochaete chrysosporium (PcBxl3), and the other from the ascomycete Trichoderma reesei (TrXyl3A). A comparison of the crystal structures of the two enzymes, both with saccharide bound at the catalytic center, provided insight into the basis of substrate binding at each subsite. PcBxl3 has a substrate-binding pocket at subsite -1, while TrXyl3A has an extra loop that contains additional binding subsites. Furthermore, kinetic experiments revealed that PcBxl3 degraded xylooligosaccharides faster than TrXyl3A, while the KM values of TrXyl3A were lower than those of PcBxl3. The relationship between substrate specificity and degree of polymerization of substrates suggested that PcBxl3 preferentially degrades xylobiose (X2), while TrXyl3A degrades longer xylooligosaccharides. Moreover, docking simulation supported the existence of extended positive subsites of TrXyl3A in the extra loop located at the N-terminus of the protein. Finally, phylogenetic analysis suggests that wood-decaying basidiomycetes use Bxls such as PcBxl3 that act efficiently on xylan structures from woody plants, whereas molds use instead Bxls that efficiently degrade xylan from grass. Our results provide added insights into fungal efficient xylan degradation systems.
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Affiliation(s)
- Keisuke Kojima
- Department of Biomaterial Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Naoki Sunagawa
- Department of Biomaterial Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan
| | - Nils Egil Mikkelsen
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, Uppsala SE-750 07, Sweden
| | - Henrik Hansson
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, Uppsala SE-750 07, Sweden
| | - Saeid Karkehabadi
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, Uppsala SE-750 07, Sweden
| | - Masahiro Samejima
- Department of Biomaterial Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan; Faculty of Engineering, Shinshu University, 4-17-1, Wakasato, Nagano 380-8533, Japan
| | - Mats Sandgren
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, Uppsala SE-750 07, Sweden
| | - Kiyohiko Igarashi
- Department of Biomaterial Sciences, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 1-1-1, Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan; VTT Technical Research Centre of Finland, PO Box 1000, Tietotie 2, Espoo FI-02044 VTT, Finland.
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8
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Álvarez C, González A, Ballesteros I, Negro MJ. Production of xylooligosaccharides, bioethanol, and lignin from structural components of barley straw pretreated with a steam explosion. BIORESOURCE TECHNOLOGY 2021; 342:125953. [PMID: 34555750 DOI: 10.1016/j.biortech.2021.125953] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 09/10/2021] [Accepted: 09/12/2021] [Indexed: 06/13/2023]
Abstract
Barley straw (BS) is a potential source to obtain bioethanol and value-added products such as xylooligosaccharides (XOS) and lignin for application in diverse industries. In this study, BS was submitted to steam explosion pretreatment to valorize the main components of this lignocellulose biomass. For hemicellulose fraction valorization, different combinations of endo-β-(1,4)-D-xylanase enzyme with accessory enzymes (α-L-arabinofuranosidase, feruloy -esterase and acetylxylan-esterase) have been studied to produce XOS with a low degree of polymerization. The application of accessory enzymes combined with endo-β-(1,4)-D-xylanase enzymes turned out to be the most effective strategy for the formation of XOS. The solid fraction obtained after the pretreatment was submitted to presacharification and simultaneous saccharification and fermentation process for bioethanol production. The resulting lignin-rich residue was characterized. In this integrated process, 13.0 g XOS (DP2-DP6), 12.6 g ethanol and 16.6 g lignin were obtained from 100 g of BS, achieving the goal of valorizing this agricultural residue.
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Affiliation(s)
- Cristina Álvarez
- Advanced Biofuels and Bioproducts Unit, Renewable Energies Department, CIEMAT, Madrid 28040, Spain.
| | - Alberto González
- Advanced Biofuels and Bioproducts Unit, Renewable Energies Department, CIEMAT, Madrid 28040, Spain.
| | - Ignacio Ballesteros
- Advanced Biofuels and Bioproducts Unit, Renewable Energies Department, CIEMAT, Madrid 28040, Spain.
| | - María José Negro
- Advanced Biofuels and Bioproducts Unit, Renewable Energies Department, CIEMAT, Madrid 28040, Spain.
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Støpamo FG, Røhr ÅK, Mekasha S, Petrović DM, Várnai A, Eijsink VGH. Characterization of a lytic polysaccharide monooxygenase from Aspergillus fumigatus shows functional variation among family AA11 fungal LPMOs. J Biol Chem 2021; 297:101421. [PMID: 34798071 PMCID: PMC8668981 DOI: 10.1016/j.jbc.2021.101421] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 11/05/2021] [Accepted: 11/08/2021] [Indexed: 11/26/2022] Open
Abstract
The discovery of oxidative cleavage of recalcitrant polysaccharides by lytic polysaccharide monooxygenases (LPMOs) has affected the study and industrial application of enzymatic biomass processing. Despite being widespread in fungi, LPMOs belonging to the auxiliary activity (AA) family AA11 have been understudied. While these LPMOs are considered chitin active, some family members have little or no activity toward chitin, and the only available crystal structure of an AA11 LPMO lacks features found in bacterial chitin-active AA10 LPMOs. Here, we report structural and functional characteristics of a single-domain AA11 LPMO from Aspergillus fumigatus, AfAA11A. The crystal structure shows a substrate-binding surface with features resembling those of known chitin-active LPMOs. Indeed, despite the absence of a carbohydrate-binding module, AfAA11A has considerable affinity for α-chitin and, more so, β-chitin. AfAA11A is active toward both these chitin allomorphs and enhances chitin degradation by an endoacting chitinase, in particular for α-chitin. The catalytic activity of AfAA11A on chitin increases when supplying reactions with hydrogen peroxide, showing that, like LPMOs from other families, AfAA11A has peroxygenase activity. These results show that, in stark contrast to the previously characterized AfAA11B from the same organism, AfAA11A likely plays a role in fungal chitin turnover. Thus, members of the hitherto rather enigmatic family of AA11 LPMOs show considerable structural and functional differences and may have multiple roles in fungal physiology.
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Affiliation(s)
- Fredrik Gjerstad Støpamo
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), Ås, Norway
| | - Åsmund Kjendseth Røhr
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), Ås, Norway
| | - Sophanit Mekasha
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), Ås, Norway
| | - Dejan M Petrović
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), Ås, Norway
| | - Anikó Várnai
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), Ås, Norway
| | - Vincent G H Eijsink
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), Ås, Norway.
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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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11
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Extraction and characterization of xylan from sugarcane tops as a potential commercial substrate. J Biosci Bioeng 2021; 131:647-654. [PMID: 33676868 DOI: 10.1016/j.jbiosc.2021.01.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 01/26/2021] [Accepted: 01/28/2021] [Indexed: 01/17/2023]
Abstract
Xylan is the major hemicellulose present in sugarcane stem secondary cell walls. Xylan is composed of xylose backbone with a high degree of substitutions, which affects its properties. In the present study, the xylan from sugarcane tops (SCT) was extracted and characterized. Compositional analysis of xylan extracted from SCT (SCTx) displayed the presence of 74% of d-xylose residues, 16% of d-glucuronic acid residues and 10% of l-arabinose. High performance size exclusion chromatographic analysis of SCTx displayed a single peak corresponding to a molecular mass of ∼57 kDa. The Fourier transform infrared spectroscopic analysis of SCTx displayed the peaks corresponding to those obtained from commercial xylan. FESEM analysis of SCTx showed the granular and porous surface structure. Differential thermogravimetric analysis (DTG) of SCTx displayed two thermal degradation temperatures (Td) of 228°C, due to breakdown of the side chains of glucuronic acid and arabinose and 275°C, due to breakdown of xylan back bone. The presence of arabinose and glucuronic acid as a side chains was confirmed by the DTG and thermogravimetric analysis. The CHNS analysis of SCTx showed the presence of only carbon and hydrogen supporting its purity. The recombinant xylanase (CtXyn11A) from Clostridium thermocellum displayed a specific activity of 1394 ± 51 U/mg with SCTx, which was higher than those with commercial xylans. The thin layer chromatography and electrospray ionization mass spectroscopy analyses of CtXyn11A hydrolysed SCTx contained a series of linear xylo-oligosaccharides ranging from degree of polymerization 2-6 and no substituted xylo-oligosaccharides because of the endolytic activity of enzyme. The extracted xylan from SCT can be used as an alternative commercial substrate and for oligo-saccharide production.
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Qaseem MF, Wu AM. Balanced Xylan Acetylation is the Key Regulator of Plant Growth and Development, and Cell Wall Structure and for Industrial Utilization. Int J Mol Sci 2020; 21:ijms21217875. [PMID: 33114198 PMCID: PMC7660596 DOI: 10.3390/ijms21217875] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2020] [Revised: 10/21/2020] [Accepted: 10/21/2020] [Indexed: 12/27/2022] Open
Abstract
Xylan is the most abundant hemicellulose, constitutes about 25–35% of the dry biomass of woody and lignified tissues, and occurs up to 50% in some cereal grains. The accurate degree and position of xylan acetylation is necessary for xylan function and for plant growth and development. The post synthetic acetylation of cell wall xylan, mainly regulated by Reduced Wall Acetylation (RWA), Trichome Birefringence-Like (TBL), and Altered Xyloglucan 9 (AXY9) genes, is essential for effective bonding of xylan with cellulose. Recent studies have proven that not only xylan acetylation but also its deacetylation is vital for various plant functions. Thus, the present review focuses on the latest advances in understanding xylan acetylation and deacetylation and explores their effects on plant growth and development. Baseline knowledge about precise regulation of xylan acetylation and deacetylation is pivotal to developing plant biomass better suited for second-generation liquid biofuel production.
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Affiliation(s)
- Mirza Faisal Qaseem
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, South China Agricultural University, Guangzhou 510642, China;
- Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architectures, South China Agricultural University, Guangzhou 510642, China
| | - Ai-Min Wu
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, South China Agricultural University, Guangzhou 510642, China;
- Guangdong Key Laboratory for Innovative Development and Utilization of Forest Plant Germplasm, College of Forestry and Landscape Architectures, South China Agricultural University, Guangzhou 510642, China
- Guangdong Laboratory of Lingnan Modern Agriculture, Guangzhou 510642, China
- Correspondence:
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Sharma K, Khaire KC, Thakur A, Moholkar VS, Goyal A. Acacia Xylan as a Substitute for Commercially Available Xylan and Its Application in the Production of Xylooligosaccharides. ACS OMEGA 2020; 5:13729-13738. [PMID: 32566838 PMCID: PMC7301597 DOI: 10.1021/acsomega.0c00896] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Accepted: 05/19/2020] [Indexed: 05/08/2023]
Abstract
Over the past two decades, birchwood and beechwood xylans have been used as a popular substrate for the characterization of xylanases. Recently, major companies have discontinued their commercial production. Therefore, there is a need to find an alternative to these substrates. Xylan extraction from Acacia sawdust resulted in 23.5% (w/w) yield. The extracted xylan is composed of xylose and glucuronic acid residues in a molar ratio of 6:1 with a molecular mass of ∼70 kDa. The specific optical rotation analysis of extracted xylan displayed that it is composed of the d-form of xylose and glucuronic acid monomeric sugars. The nuclear magnetic resonance analysis of extracted xylan revealed that the xylan backbone is substituted with 4-O-methyl glucuronic acid at the O2 position. Fourier transform infrared analysis confirmed the absence of lignin contamination in the extracted xylan. Xylanase from Clostridium thermocellum displayed the enzyme activity of 1761 U/mg against extracted xylan, and the corresponding activity against beechwood xylan was 1556 U/mg, which confirmed that the extracted xylan could be used as an alternative substrate for the characterization of xylanases.
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Affiliation(s)
- Kedar Sharma
- Carbohydrate
Enzyme Biotechnology Laboratory, Center for Energy, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India
| | - Kaustubh Chandrakant Khaire
- Carbohydrate
Enzyme Biotechnology Laboratory, Center for Energy, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India
| | - Abhijeet Thakur
- Carbohydrate
Enzyme Biotechnology Laboratory, Center for Energy, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India
| | - Vijayanand Suryakant Moholkar
- Carbohydrate
Enzyme Biotechnology Laboratory, Center for Energy, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India
| | - Arun Goyal
- Carbohydrate
Enzyme Biotechnology Laboratory, Center for Energy, Indian Institute of Technology Guwahati, Guwahati 781039, Assam, India
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Arnaud B, Durand S, Fanuel M, Guillon F, Méchin V, Rogniaux H. Imaging Study by Mass Spectrometry of the Spatial Variation of Cellulose and Hemicellulose Structures in Corn Stalks. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2020; 68:4042-4050. [PMID: 32125840 DOI: 10.1021/acs.jafc.9b07579] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The study used mass spectrometry imaging (MSI) to map the distribution of enzymatically degraded cell wall polysaccharides in maize stems for two genotypes and at several stages of development. The context was the production of biofuels, and the overall objective was to better describe the structural determinants of recalcitrance of grasses in bioconversion. The selected genotypes showed contrasting characteristics in bioconversion assays as well as in their lignin deposition pattern. We compared the pattern of cell wall polysaccharide degradation observed by MSI following the enzymatic degradation of tissues with that of lignin deposition. Several enzymes targeting the main families of wall polysaccharides were used. In the early stages of development, cellulose and mixed-linked β-glucans appeared as the main polysaccharides degraded from the walls, while heteroxylan products were barely detected, suggesting subsequent deposition of heteroxylans in the walls. At all stages and for both genotypes, enzymatic degradation occurred preferentially in nonlignified walls for all structural families of polysaccharides studied here. However, our results showed heterogeneity in the distribution of heteroxylan products according to their chemical structure: arabinosylated products were mostly represented in the pith center, while glucuronylated products were found at the pith periphery. The conclusions of our work are in agreement with those of previous studies. The MSI approach presented here is unique and attractive for addressing the histological and biochemical aspects of biomass recalcitrance to conversion, as it allows for a simultaneous interpretation of cell wall degradation and lignification patterns at the scale of an entire stem section.
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Affiliation(s)
- B Arnaud
- INRAE, UR BIA, F-44316 Nantes, France
- INRAE, BIBS Facility, F-44316 Nantes, France
- Institut Jean-Pierre Bourgin, INRAE, AgroParisTech, Université Paris-Saclay, F-78000 Versailles, France
| | - S Durand
- INRAE, UR BIA, F-44316 Nantes, France
| | - M Fanuel
- INRAE, UR BIA, F-44316 Nantes, France
- INRAE, BIBS Facility, F-44316 Nantes, France
| | - F Guillon
- INRAE, UR BIA, F-44316 Nantes, France
| | - V Méchin
- Institut Jean-Pierre Bourgin, INRAE, AgroParisTech, Université Paris-Saclay, F-78000 Versailles, France
| | - H Rogniaux
- INRAE, UR BIA, F-44316 Nantes, France
- INRAE, BIBS Facility, F-44316 Nantes, France
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15
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A pair of esterases from a commensal gut bacterium remove acetylations from all positions on complex β-mannans. Proc Natl Acad Sci U S A 2020; 117:7122-7130. [PMID: 32170022 DOI: 10.1073/pnas.1915376117] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
β-mannans and xylans are important components of the plant cell wall and they are acetylated to be protected from degradation by glycoside hydrolases. β-mannans are widely present in human and animal diets as fiber from leguminous plants and as thickeners and stabilizers in processed foods. There are many fully characterized acetylxylan esterases (AcXEs); however, the enzymes deacetylating mannans are less understood. Here we present two carbohydrate esterases, RiCE2 and RiCE17, from the Firmicute Roseburia intestinalis, which together deacetylate complex galactoglucomannan (GGM). The three-dimensional (3D) structure of RiCE17 with a mannopentaose in the active site shows that the CBM35 domain of RiCE17 forms a confined complex, where the axially oriented C2-hydroxyl of a mannose residue points toward the Ser41 of the catalytic triad. Cavities on the RiCE17 surface may accept galactosylations at the C6 positions of mannose adjacent to the mannose residue being deacetylated (subsite -1 and +1). In-depth characterization of the two enzymes using time-resolved NMR, high-performance liquid chromatography (HPLC), and mass spectrometry demonstrates that they work in a complementary manner. RiCE17 exclusively removes the axially oriented 2-O-acetylations on any mannose residue in an oligosaccharide, including double acetylated mannoses, while the RiCE2 is active on 3-O-, 4-O-, and 6-O-acetylations. Activity of RiCE2 is dependent on RiCE17 removing 2-O-acetylations from double acetylated mannose. Furthermore, transacetylation of oligosaccharides with the 2-O-specific RiCE17 provided insight into how temperature and pH affects acetyl migration on manno-oligosaccharides.
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Puchart V, Gjermansen M, Mastihubová M, Mørkeberg Krogh KB, Biely P. Positional specificity of Flavobacterium johnsoniae acetylxylan esterase and acetyl group migration on xylan main chain. Carbohydr Polym 2020; 232:115783. [DOI: 10.1016/j.carbpol.2019.115783] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 12/11/2019] [Accepted: 12/24/2019] [Indexed: 02/06/2023]
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Discovery of a Thermostable GH10 Xylanase with Broad Substrate Specificity from the Arctic Mid-Ocean Ridge Vent System. Appl Environ Microbiol 2019; 85:AEM.02970-18. [PMID: 30635385 DOI: 10.1128/aem.02970-18] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Accepted: 01/03/2019] [Indexed: 11/20/2022] Open
Abstract
A two-domain GH10 xylanase-encoding gene (amor_gh10a) was discovered from a metagenomic data set, generated after in situ incubation of a lignocellulosic substrate in hot sediments on the sea floor of the Arctic Mid-Ocean Ridge (AMOR). AMOR_GH10A comprises a signal peptide, a carbohydrate-binding module belonging to a previously uncharacterized family, and a catalytic glycosyl hydrolase (GH10) domain. The enzyme shares the highest sequence identity (42%) with a hypothetical protein from a Verrucomicrobia bacterium, and its GH10 domain shares low identity (24 to 28%) with functionally characterized xylanases. Purified AMOR_GH10A showed thermophilic and halophilic properties and was active toward various xylans. Uniquely, the enzyme showed high activity toward amorphous cellulose, glucomannan, and xyloglucan and was more active toward cellopentaose than toward xylopentaose. Binding assays showed that the N-terminal domain of this broad-specificity GH10 binds strongly to amorphous cellulose, as well as to microcrystalline cellulose, birchwood glucuronoxylan, barley β-glucan, and konjac glucomannan, confirming its classification as a novel CBM (CBM85).IMPORTANCE Hot springs at the sea bottom harbor unique biodiversity and are a promising source of enzymes with interesting properties. We describe the functional characterization of a thermophilic and halophilic multidomain xylanase originating from the Arctic Mid-Ocean Ridge vent system, belonging to the well-studied family 10 of glycosyl hydrolases (GH10). This xylanase, AMOR_GH10A, has a surprisingly wide substrate range and is more active toward cellopentaose than toward xylopentaose. This substrate promiscuity is unique for the GH10 family and could prove useful in industrial applications. Emphasizing the versatility of AMOR_GH10A, its N-terminal domain binds to both xylans and glycans, while not showing significant sequence similarities to any known carbohydrate-binding module (CBM) in the CAZy database. Thus, this N-terminal domain lays the foundation for the new CBM85 family.
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18
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Puchart V, Mørkeberg Krogh KB, Biely P. Glucuronoxylan 3-O-acetylated on uronic acid-substituted xylopyranosyl residues and its hydrolysis by GH10, GH11 and GH30 endoxylanases. Carbohydr Polym 2019; 205:217-224. [DOI: 10.1016/j.carbpol.2018.10.043] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Revised: 10/11/2018] [Accepted: 10/14/2018] [Indexed: 11/26/2022]
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19
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Abstract
Woody biomass is a sustainable and virtually unlimited source of hemicellulosic polysaccharides. The predominant hemicelluloses in softwood and hardwood are galactoglucomannan (GGM) and arabinoglucuronoxylan (AGX), respectively. Based on the structure similarity with common dietary fibers, GGM and AGX may be postulated to have prebiotic properties, conferring a health benefit on the host through specific modulation of the gut microbiota. In this study, we evaluated the prebiotic potential of acetylated GGM (AcGGM) and highly acetylated AGX (AcAGX) obtained from Norwegian lignocellulosic feedstocks in vitro In pure culture, both substrates selectively promoted the growth of Bifidobacterium, Lactobacillus, and Bacteroides species in a manner consistent with the presence of genetic loci for the utilization of β-manno-oligosaccharides/β-mannans and xylo-oligosaccharides/xylans. The prebiotic potential of AcGGM and AcAGX was further assessed in a pH-controlled batch culture fermentation system inoculated with healthy adult human feces. Results were compared with those obtained with a commercial fructo-oligosaccharide (FOS) mixture. Similarly to FOS, both substrates significantly increased (P < 0.05) the Bifidobacterium population. Other bacterial groups enumerated were unaffected with the exception of an increase in the growth of members of the Bacteroides-Prevotella group, Faecalibacterium prausnitzii, and clostridial cluster IX (P < 0.05). Compared to the other substrates, AcGGM promoted butyrogenic fermentation whereas AcAGX was more propiogenic. Although further in vivo confirmation is necessary, these results demonstrate that both AcGGM and AcAGX from lignocellulosic feedstocks can be used to direct the promotion of beneficial bacteria, thus exhibiting a promising prebiotic ability to improve or restore gut health.IMPORTANCE The architecture of the gut bacterial ecosystem has a profound effect on the physiology and well-being of the host. Modulation of the gut microbiota and the intestinal microenvironment via administration of prebiotics represents a valuable strategy to promote host health. This work provides insights into the ability of two novel wood-derived preparations, AcGGM and AcAGX, to influence human gut microbiota composition and activity. These compounds were selectively fermented by commensal bacteria such as Bifidobacterium, Bacteroides-Prevotella, F. prausnitzii, and clostridial cluster IX spp. This promoted the microbial synthesis of acetate, propionate, and butyrate, which are beneficial to the microbial ecosystem and host colonic epithelial cells. Thus, our results demonstrate potential prebiotic properties for both AcGGM and AcAGX from lignocellulosic feedstocks. These findings represent pivotal requirements for rationally designing intervention strategies based on the dietary supplementation of AcGGM and AcAGX to improve or restore gut health.
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20
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Arumugam N, Biely P, Puchart V, Singh S, Pillai S. Structure of peanut shell xylan and its conversion to oligosaccharides. Process Biochem 2018. [DOI: 10.1016/j.procbio.2018.06.024] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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21
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Harvey DJ. Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update for 2013-2014. MASS SPECTROMETRY REVIEWS 2018; 37:353-491. [PMID: 29687922 DOI: 10.1002/mas.21530] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2016] [Accepted: 11/29/2016] [Indexed: 06/08/2023]
Abstract
This review is the eighth update of the original article published in 1999 on the application of Matrix-assisted laser desorption/ionization mass spectrometry (MALDI) mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2014. Topics covered in the first part of the review include general aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, fragmentation, and arrays. The second part of the review is devoted to applications to various structural types such as oligo- and poly- saccharides, glycoproteins, glycolipids, glycosides, and biopharmaceuticals. Much of this material is presented in tabular form. The third part of the review covers medical and industrial applications of the technique, studies of enzyme reactions, and applications to chemical synthesis. © 2018 Wiley Periodicals, Inc. Mass Spec Rev 37:353-491, 2018.
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Affiliation(s)
- David J Harvey
- Target Discovery Institute, Nuffield Department of Medicine, University of Oxford, Roosevelt Drive, Oxford, OX3 7FZ, United Kingdom
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22
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Sharma K, Antunes IL, Rajulapati V, Goyal A. Molecular characterization of a first endo-acting β-1,4-xylanase of family 10 glycoside hydrolase (PsGH10A) from Pseudopedobacter saltans comb. nov. Process Biochem 2018. [DOI: 10.1016/j.procbio.2018.03.025] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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23
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Leth ML, Ejby M, Workman C, Ewald DA, Pedersen SS, Sternberg C, Bahl MI, Licht TR, Aachmann FL, Westereng B, Abou Hachem M. Differential bacterial capture and transport preferences facilitate co-growth on dietary xylan in the human gut. Nat Microbiol 2018; 3:570-580. [PMID: 29610517 DOI: 10.1038/s41564-018-0132-8] [Citation(s) in RCA: 108] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Accepted: 02/19/2018] [Indexed: 12/11/2022]
Abstract
Metabolism of dietary glycans is pivotal in shaping the human gut microbiota. However, the mechanisms that promote competition for glycans among gut commensals remain unclear. Roseburia intestinalis, an abundant butyrate-producing Firmicute, is a key degrader of the major dietary fibre xylan. Despite the association of this taxon to a healthy microbiota, insight is lacking into its glycan utilization machinery. Here, we investigate the apparatus that confers R. intestinalis growth on different xylans. R. intestinalis displays a large cell-attached modular xylanase that promotes multivalent and dynamic association to xylan via four xylan-binding modules. This xylanase operates in concert with an ATP-binding cassette transporter to mediate breakdown and selective internalization of xylan fragments. The transport protein of R. intestinalis prefers oligomers of 4-5 xylosyl units, whereas the counterpart from a model xylan-degrading Bacteroides commensal targets larger ligands. Although R. intestinalis and the Bacteroides competitor co-grew in a mixed culture on xylan, R. intestinalis dominated on the preferred transport substrate xylotetraose. These findings highlight the differentiation of capture and transport preferences as a possible strategy to facilitate co-growth on abundant dietary fibres and may offer a unique route to manipulate the microbiota based on glycan transport preferences in therapeutic interventions to boost distinct taxa.
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Affiliation(s)
- Maria Louise Leth
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Lyngby, Denmark
| | - Morten Ejby
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Lyngby, Denmark
| | - Christopher Workman
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Lyngby, Denmark
| | - David Adrian Ewald
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Lyngby, Denmark
| | - Signe Schultz Pedersen
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Lyngby, Denmark
| | - Claus Sternberg
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Lyngby, Denmark
| | - Martin Iain Bahl
- National Food Institute, Technical University of Denmark, Lyngby, Denmark
| | - Tine Rask Licht
- National Food Institute, Technical University of Denmark, Lyngby, Denmark
| | - Finn Lillelund Aachmann
- NOBIPOL, Department of Biotechnology and Food Science, NTNU Norwegian University of Science and Technology, Trondheim, Norway
| | - Bjørge Westereng
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Ås, Norway
| | - Maher Abou Hachem
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Lyngby, Denmark.
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Substrate Recognition and Specificity of Chitin Deacetylases and Related Family 4 Carbohydrate Esterases. Int J Mol Sci 2018; 19:ijms19020412. [PMID: 29385775 PMCID: PMC5855634 DOI: 10.3390/ijms19020412] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2017] [Revised: 01/22/2018] [Accepted: 01/24/2018] [Indexed: 12/27/2022] Open
Abstract
Carbohydrate esterases family 4 (CE4 enzymes) includes chitin and peptidoglycan deacetylases, acetylxylan esterases, and poly-N-acetylglucosamine deacetylases that act on structural polysaccharides, altering their physicochemical properties, and participating in diverse biological functions. Chitin and peptidoglycan deacetylases are not only involved in cell wall morphogenesis and remodeling in fungi and bacteria, but they are also used by pathogenic microorganisms to evade host defense mechanisms. Likewise, biofilm formation in bacteria requires partial deacetylation of extracellular polysaccharides mediated by poly-N-acetylglucosamine deacetylases. Such biological functions make these enzymes attractive targets for drug design against pathogenic fungi and bacteria. On the other side, acetylxylan esterases deacetylate plant cell wall complex xylans to make them accessible to hydrolases, making them attractive biocatalysts for biomass utilization. CE4 family members are metal-dependent hydrolases. They are highly specific for their particular substrates, and show diverse modes of action, exhibiting either processive, multiple attack, or patterned deacetylation mechanisms. However, the determinants of substrate specificity remain poorly understood. Here, we review the current knowledge on the structure, activity, and specificity of CE4 enzymes, focusing on chitin deacetylases and related enzymes active on N-acetylglucosamine-containing oligo and polysaccharides.
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25
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Action of different types of endoxylanases on eucalyptus xylan in situ. Appl Microbiol Biotechnol 2018; 102:1725-1736. [PMID: 29302718 DOI: 10.1007/s00253-017-8722-6] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Revised: 12/13/2017] [Accepted: 12/17/2017] [Indexed: 10/18/2022]
Abstract
Most studies of the mode of action of industrially important endoxylanases have been done on alkali extracted-plant xylan. In just few cases, the native form of the polysaccharide, acetylated xylan, was used as a substrate. In this work action of xylanases belonging to three glycoside hydrolase families, GH10, GH11, and GH30 was investigated on acetylglucuronoxylan directly in hardwood cell walls. Powdered eucalyptus wood was used as xylanase substrate. Enzyme-generated fragments were characterized by TLC, MALDI ToF MS, and NMR spectroscopy. All three xylanases generated from eucalyptus wood powder acetylated xylooligosaccharides. Those released by GH10 enzyme were the shortest, and those released by GH30 xylanase were of the largest diversity. For GH30 xylanase the 4-O-methyl-D-glucuronic acid (MeGlcA) side residues function as substrate specificity determinants regardless the acetylation of the neighboring hydroxyl group. Much simpler xylooligosaccharide patterns were observed when xylanases were applied in combination with carbohydrate esterase family 6 acetylxylan esterase. In the presence of the esterase, all aldouronic acids remained 3-O-acetylated on the xylopyranosyl (Xylp) residue substituted with MeGlcA. The 3-O-acetyl group, in contrast to the acetyl groups of otherwise unsubstituted Xylp residues, does not affect the mode of action of endoxylanases, but contributes to recalcitrance of the acidic xylan fragments. The results confirm importance of acetylxylan esterases in microbial degradation of acetylated hardwood glucuronoxylan. They also point to still unresolved question of efficient enzymatic removal of the 3-O-acetyl group on MeGlcA-substituted Xylp residues negatively affecting the saccharification yields.
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26
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Michalak L, Knutsen SH, Aarum I, Westereng B. Effects of pH on steam explosion extraction of acetylated galactoglucomannan from Norway spruce. BIOTECHNOLOGY FOR BIOFUELS 2018; 11:311. [PMID: 30455740 PMCID: PMC6225635 DOI: 10.1186/s13068-018-1300-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Accepted: 10/24/2018] [Indexed: 05/15/2023]
Abstract
BACKGROUND Acetylated galactoglucomannan (AcGGM) is a complex hemicellulose found in softwoods such as Norway spruce (Picea abies). AcGGM has a large potential as a biorefinery feedstock and source of oligosaccharides for high-value industrial applications. Steam explosion is an effective method for extraction of carbohydrates from plant biomass. Increasing the reaction pH reduces the combined severity ( R 0 ' ) of treatment, affecting yields and properties of extracted oligosaccharides. In this study, steam explosion was used to extract oligosaccharides from Norway spruce wood chips soaked with sodium citrate and potassium phosphate buffers with pH of 4.0-7.0. Yields, monosaccharide composition of released oligosaccharides and biomass residue, their acetate content and composition of their lignin fraction were examined to determine the impact of steam explosion buffering on the extraction of softwood hemicellulose. RESULTS Reducing the severity of steam explosion resulted in lower yields, although the extracted oligosaccharides had a higher degree of polymerization. Higher buffering pH also resulted in a higher fraction of xylan in the extracted oligos. Oligosaccharides extracted in buffers of pH > 5.0 were deacetylated. Buffering leads to a removal of acetylations from both the extracted oligosaccharides and the hemicellulose in the residual biomass. Treatment of the residual biomass with a GH5 family mannanase from Aspergillus nidulans was not able to improve the AcGGM yields. No hydroxymethylfurfural formation, a decomposition product from hexoses, was observed in samples soaked with buffers at pH higher than 4.0. CONCLUSIONS Buffering the steam explosion reactions proved to be an effective way to reduce the combined severity ( R 0 ' ) and produce a wide range of products from the same feedstock at the same physical conditions. The results highlight the impact of chemical autohydrolysis of hemicellulose by acetic acid released from the biomass in hydrothermal pretreatments. Lower combined severity results in products with a lower degree of acetylation of both the extracted oligosaccharides and residual biomass. Decrease in severity appears not to be the result of reduced acetate release, but rather a result of inhibited autohydrolysis by the released acetate. Based on the results presented, the optimal soaking pH for fine-tuning properties of extracted AcGGM is below 5.0.
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Affiliation(s)
- Leszek Michalak
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Ås, Norway
| | - Svein Halvor Knutsen
- Nofima, Norwegian Institute of Food, Fishery and Aquaculture Research, PB 210, 1431 Ås, Norway
| | - Ida Aarum
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Ås, Norway
| | - Bjørge Westereng
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Ås, Norway
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27
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Kanokratana P, Wongwilaiwalin S, Mhuantong W, Tangphatsornruang S, Eurwilaichitr L, Champreda V. Characterization of cellulolytic microbial consortium enriched on Napier grass using metagenomic approaches. J Biosci Bioeng 2017; 125:439-447. [PMID: 29169786 DOI: 10.1016/j.jbiosc.2017.10.014] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2017] [Revised: 09/11/2017] [Accepted: 10/25/2017] [Indexed: 11/17/2022]
Abstract
Energy grass is a promising substrate for production of biogas by anaerobic digestion. However, the conversion efficiency is limited by the enzymatically recalcitrant nature of cellulosic wastes. In this study, an active, structurally stable mesophilic lignocellulolytic degrading microbial consortium (Np-LMC) was constructed from forest compost soil microbiota by successive subcultivation on Napier grass under facultative anoxic conditions. According to tagged 16S rRNA gene amplicon sequencing, increasing abundance of facultative Proteobacteria was found in the middle of batch cycle which was then subsequently replaced by the cellulose degraders Firmicutes and Bacteroidetes along with decreasing CMCase, xylanase, and β-glucanase activity profiles in the supernatant after 5 days of incubation. Anaerobic/facultative bacteria Dysgonomonas and Sedimentibacter and aerobic bacteria Comamonas were the major genera found in Np-LMC. The consortium was active on degradation of the native and delignified grass. Direct shotgun sequencing of the consortium metagenome revealed relatively high abundance of genes encoding for various lignocellulose degrading enzymes in 23 glycosyl hydrolase (GH) families compared to previously reported cellulolytic microbial communities in mammalian digestive tracts. Enzymes attacking cellulose and hemicellulose were dominated by GH2, 3, 5, 9, 10, 26, 28 and 43 in addition to a variety of carbohydrate esterases (CE) and auxiliary activities (AA), reflecting adaptation of the enzyme systems to the native herbaceous substrate. The consortium identified here represents the microcosm specifically bred on energy grass, with potential for enhancing degradation of fibrous substrates in bioenergy industry.
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Affiliation(s)
- Pattanop Kanokratana
- Enzyme Technology Laboratory, National Center for Genetic Engineering and Biotechnology, 113 Thailand Science Park, Pahonyothin Road, Klong Luang, Pathum Thani 12120, Thailand.
| | - Sarunyou Wongwilaiwalin
- Enzyme Technology Laboratory, National Center for Genetic Engineering and Biotechnology, 113 Thailand Science Park, Pahonyothin Road, Klong Luang, Pathum Thani 12120, Thailand
| | - Wuttichai Mhuantong
- Enzyme Technology Laboratory, National Center for Genetic Engineering and Biotechnology, 113 Thailand Science Park, Pahonyothin Road, Klong Luang, Pathum Thani 12120, Thailand
| | - Sithichoke Tangphatsornruang
- Genomic Research Laboratory, National Center for Genetic Engineering and Biotechnology, 113 Thailand Science Park, Pahonyothin Road, Klong Luang, Pathum Thani 12120, Thailand
| | - Lily Eurwilaichitr
- Enzyme Technology Laboratory, National Center for Genetic Engineering and Biotechnology, 113 Thailand Science Park, Pahonyothin Road, Klong Luang, Pathum Thani 12120, Thailand
| | - Verawat Champreda
- Enzyme Technology Laboratory, National Center for Genetic Engineering and Biotechnology, 113 Thailand Science Park, Pahonyothin Road, Klong Luang, Pathum Thani 12120, Thailand
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Arntzen MØ, Várnai A, Mackie RI, Eijsink VGH, Pope PB. Outer membrane vesicles from Fibrobacter succinogenes S85 contain an array of carbohydrate-active enzymes with versatile polysaccharide-degrading capacity. Environ Microbiol 2017; 19:2701-2714. [PMID: 28447389 DOI: 10.1111/1462-2920.13770] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Accepted: 04/18/2017] [Indexed: 11/30/2022]
Abstract
Fibrobacter succinogenes is an anaerobic bacterium naturally colonising the rumen and cecum of herbivores where it utilizes an enigmatic mechanism to deconstruct cellulose into cellobiose and glucose, which serve as carbon sources for growth. Here, we illustrate that outer membrane vesicles (OMVs) released by F. succinogenes are enriched with carbohydrate-active enzymes and that intact OMVs were able to depolymerize a broad range of linear and branched hemicelluloses and pectin, despite the inability of F. succinogenes to utilize non-cellulosic (pentose) sugars for growth. We hypothesize that the degradative versatility of F. succinogenes OMVs is used to prime hydrolysis by destabilising the tight networks of polysaccharides intertwining cellulose in the plant cell wall, thus increasing accessibility of the target substrate for the host cell. This is supported by observations that OMV-pretreatment of the natural complex substrate switchgrass increased the catalytic efficiency of a commercial cellulose-degrading enzyme cocktail by 2.4-fold. We also show that the OMVs contain a putative multiprotein complex, including the fibro-slime protein previously found to be important in binding to crystalline cellulose. We hypothesize that this complex has a function in plant cell wall degradation, either by catalysing polysaccharide degradation itself, or by targeting the vesicles to plant biomass.
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Affiliation(s)
- Magnus Ø Arntzen
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Ås, Norway
| | - Anikó Várnai
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Ås, Norway
| | - Roderick I Mackie
- Institute for Genomic Biology, and Department of Animal Sciences, University of Illinois at Urbana-Champaign, IL, USA
| | - Vincent G H Eijsink
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Ås, Norway
| | - Phillip B Pope
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Ås, Norway
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Structure and function of a broad-specificity chitin deacetylase from Aspergillus nidulans FGSC A4. Sci Rep 2017; 7:1746. [PMID: 28496100 PMCID: PMC5431758 DOI: 10.1038/s41598-017-02043-1] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Accepted: 04/06/2017] [Indexed: 02/05/2023] Open
Abstract
Enzymatic conversion of chitin, a β-1,4 linked polymer of N-acetylglucosamine, is of major interest in areas varying from the biorefining of chitin-rich waste streams to understanding how medically relevant fungi remodel their chitin-containing cell walls. Although numerous chitinolytic enzymes have been studied in detail, relatively little is known about enzymes capable of deacetylating chitin. We describe the structural and functional characterization of a 237 residue deacetylase (AnCDA) from Aspergillus nidulans FGSC A4. AnCDA acts on chito-oligomers, crystalline chitin, chitosan, and acetylxylan, but not on peptidoglycan. The Km and kcat of AnCDA for the first deacetylation of penta-N-acetyl-chitopentaose are 72 µM and 1.4 s−1, respectively. Combining mass spectrometry and analyses of acetate release, it was shown that AnCDA catalyses mono-deacetylation of (GlcNAc)2 and full deacetylation of (GlcNAc)3–6 in a non-processive manner. Deacetylation of the reducing end sugar was much slower than deacetylation of the other sugars in chito-oligomers. These enzymatic characteristics are discussed in the light of the crystal structure of AnCDA, providing insight into how the chitin deacetylase may interact with its substrates. Interestingly, AnCDA activity on crystalline chitin was enhanced by a lytic polysaccharide monooxygenase that increases substrate accessibility by oxidative cleavage of the chitin chains.
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Abstract
Colorimetric detection of reaction products is typically preferred for initial surveys of acetyl xylan esterase (AcXE) activity. This chapter will describe common colorimetric methods, and variations thereof, for measuring AcXE activities on commercial, synthesized, and natural substrates. Whereas assays using pNP-acetate, α-naphthyl acetate, and 4-methylumbelliferyl acetate (4MUA) are emphasized, common methods used to measure AcXE activity towards carbohydrate analogs (e.g., acetylated p-nitrophenyl β-D-xylopyranosides) and various acetylated xylans are also described. Strengths and limitations of the colorimetric assays are highlighted.
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Affiliation(s)
- Galina Mai-Gisondi
- Department of Bioproducts and Biosystems, Aalto University, 00076, Kemistintie 1, Espoo, Aalto, Finland
| | - Emma R Master
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, ON, M5S 3E5, Canada.
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31
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Adesioye FA, Makhalanyane TP, Biely P, Cowan DA. Phylogeny, classification and metagenomic bioprospecting of microbial acetyl xylan esterases. Enzyme Microb Technol 2016; 93-94:79-91. [DOI: 10.1016/j.enzmictec.2016.07.001] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Revised: 06/18/2016] [Accepted: 07/01/2016] [Indexed: 02/06/2023]
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Kwon M, Song J, Park HS, Park H, Chang J. Characterization of Heterologously Expressed Acetyl Xylan Esterase1 Isolated from the Anaerobic Rumen Fungus Neocallimastix frontalis PMA02. ASIAN-AUSTRALASIAN JOURNAL OF ANIMAL SCIENCES 2016; 29:1576-1584. [PMID: 27383808 PMCID: PMC5088377 DOI: 10.5713/ajas.16.0336] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Revised: 05/29/2016] [Accepted: 06/09/2016] [Indexed: 11/27/2022]
Abstract
Acetyl xylan esterase (AXE), which hydrolyzes the ester linkages of the naturally acetylated xylan and thus known to have an important role for hemicellulose degradation, was isolated from the anaerobic rumen fungus Neocallimastix frontatlis PMA02, heterologously expressed in Escherichi coli (E.coli) and characterized. The full-length cDNA encoding NfAXE1 was 1,494 bp, of which 978 bp constituted an open reading frame. The estimated molecular weight of NfAXE1 was 36.5 kDa with 326 amino acid residues, and the calculated isoelectric point was 4.54. The secondary protein structure was predicted to consist of nine α-helixes and 12 β-strands. The enzyme expressed in E.coli had the highest activity at 40°C and pH 8. The purified recombinant NfAXE1 had a specific activity of 100.1 U/mg when p-nitrophenyl acetate (p-NA) was used as a substrate at 40°C, optimum temperature. The amount of liberated acetic acids were the highest and the lowest when p-NA and acetylated birchwood xylan were used as substrates, respectively. The amount of xylose released from acetylated birchwod xylan was increased by 1.4 fold when NfAXE1 was mixed with xylanase in a reaction cocktail, implying a synergistic effect of NfAXE1 with xylanase on hemicellulose degradation.
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Affiliation(s)
- Mi Kwon
- InfoBoss Incorporation, Seoul 07766, Korea.,Institute of Biological Chemistry, Washington State University, Pullman, WA 99163, USA
| | - Jaeyong Song
- Department of Agricultural Science, Korea National Open University, Seoul 03087, Korea.,Department of Animal Sciences, Kyungpook National University, Sangju 37224, Korea
| | | | - Hyunjin Park
- Department of Agricultural Science, Korea National Open University, Seoul 03087, Korea
| | - Jongsoo Chang
- Department of Agricultural Science, Korea National Open University, Seoul 03087, Korea
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Towards enzymatic breakdown of complex plant xylan structures: State of the art. Biotechnol Adv 2016; 34:1260-1274. [PMID: 27620948 DOI: 10.1016/j.biotechadv.2016.09.001] [Citation(s) in RCA: 169] [Impact Index Per Article: 21.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Revised: 09/02/2016] [Accepted: 09/07/2016] [Indexed: 02/07/2023]
Abstract
Significant progress over the past few years has been achieved in the enzymology of microbial degradation and saccharification of plant xylan, after cellulose being the most abundant natural renewable polysaccharide. Several new types of xylan depolymerizing and debranching enzymes have been described in microorganisms. Despite the increasing variety of known glycoside hydrolases and carbohydrate esterases, some xylan structures still appear quite recalcitrant. This review focuses on the mode of action of different types of depolymerizing endoxylanases and their cooperation with β-xylosidase and accessory enzymes in breakdown of complex highly branched xylan structures. Emphasis is placed on the enzymatic hydrolysis of alkali-extracted deesterified polysaccharide as well as acetylated xylan isolated from plant cell walls under non-alkaline conditions. It is also shown how the combination of selected endoxylanases and debranching enzymes can determine the nature of prebiotic xylooligosaccharides or lead to complete hydrolysis of the polysaccharide. The article also highlights the possibility for discovery of novel xylanolytic enzymes, construction of multifunctional chimeric enzymes and xylanosomes in parallel with increasing knowledge on the fine structure of the polysaccharide.
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34
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Comparison of fungal carbohydrate esterases of family CE16 on artificial and natural substrates. J Biotechnol 2016; 233:228-36. [DOI: 10.1016/j.jbiotec.2016.07.003] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2016] [Revised: 06/28/2016] [Accepted: 07/06/2016] [Indexed: 01/04/2023]
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35
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Schendel RR, Puchbauer AK, Britscho N, Bunzel M. Feruloylated Wheat Bran Arabinoxylans: Isolation and Characterization of Acetylated andO–2-Monosubstituted Structures. Cereal Chem 2016. [DOI: 10.1094/cchem-12-15-0250-r] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Affiliation(s)
- Rachel R. Schendel
- Karlsruhe Institute of Technology (KIT), Institute of Applied Biosciences, Department of Food Chemistry and Phytochemistry, Adenauerring 20A, 76131 Karlsruhe, Germany
| | - Ann-Katrin Puchbauer
- Karlsruhe Institute of Technology (KIT), Institute of Applied Biosciences, Department of Food Chemistry and Phytochemistry, Adenauerring 20A, 76131 Karlsruhe, Germany
| | - Natalie Britscho
- Karlsruhe Institute of Technology (KIT), Institute of Applied Biosciences, Department of Food Chemistry and Phytochemistry, Adenauerring 20A, 76131 Karlsruhe, Germany
| | - Mirko Bunzel
- Karlsruhe Institute of Technology (KIT), Institute of Applied Biosciences, Department of Food Chemistry and Phytochemistry, Adenauerring 20A, 76131 Karlsruhe, Germany
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Mai-Gisondi G, Turunen O, Pastinen O, Pahimanolis N, Master ER. Enhancement of acetyl xylan esterase activity on cellulose acetate through fusion to a family 3 cellulose binding module. Enzyme Microb Technol 2015; 79-80:27-33. [DOI: 10.1016/j.enzmictec.2015.07.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Revised: 06/30/2015] [Accepted: 07/02/2015] [Indexed: 10/23/2022]
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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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Vidal-Melgosa S, Pedersen HL, Schückel J, Arnal G, Dumon C, Amby DB, Monrad RN, Westereng B, Willats WGT. A new versatile microarray-based method for high throughput screening of carbohydrate-active enzymes. J Biol Chem 2015; 290:9020-36. [PMID: 25657012 PMCID: PMC4423690 DOI: 10.1074/jbc.m114.630673] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Revised: 01/30/2015] [Indexed: 01/28/2023] Open
Abstract
Carbohydrate-active enzymes have multiple biological roles and industrial applications. Advances in genome and transcriptome sequencing together with associated bioinformatics tools have identified vast numbers of putative carbohydrate-degrading and -modifying enzymes including glycoside hydrolases and lytic polysaccharide monooxygenases. However, there is a paucity of methods for rapidly screening the activities of these enzymes. By combining the multiplexing capacity of carbohydrate microarrays with the specificity of molecular probes, we have developed a sensitive, high throughput, and versatile semiquantitative enzyme screening technique that requires low amounts of enzyme and substrate. The method can be used to assess the activities of single enzymes, enzyme mixtures, and crude culture broths against single substrates, substrate mixtures, and biomass samples. Moreover, we show that the technique can be used to analyze both endo-acting and exo-acting glycoside hydrolases, polysaccharide lyases, carbohydrate esterases, and lytic polysaccharide monooxygenases. We demonstrate the potential of the technique by identifying the substrate specificities of purified uncharacterized enzymes and by screening enzyme activities from fungal culture broths.
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Affiliation(s)
- Silvia Vidal-Melgosa
- From the Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, 1871 Frederiksberg, Denmark
| | - Henriette L Pedersen
- From the Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, 1871 Frederiksberg, Denmark
| | - Julia Schückel
- From the Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, 1871 Frederiksberg, Denmark
| | - Grégory Arnal
- INRA, UMR792 Ingénierie des Systèmes Biologiques et des Procédés, Toulouse F-31400, France, Université de Toulouse, INSA, UPS, INP, LISBP, 135 Avenue de Rangueil, F-31077 Toulouse, France, CNRS, UMR5504, F-31400 Toulouse, France
| | - Claire Dumon
- INRA, UMR792 Ingénierie des Systèmes Biologiques et des Procédés, Toulouse F-31400, France, Université de Toulouse, INSA, UPS, INP, LISBP, 135 Avenue de Rangueil, F-31077 Toulouse, France, CNRS, UMR5504, F-31400 Toulouse, France
| | - Daniel B Amby
- From the Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, 1871 Frederiksberg, Denmark
| | | | - Bjørge Westereng
- From the Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, 1871 Frederiksberg, Denmark, Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, 1432 Aas, Norway
| | - William G T Willats
- From the Department of Plant and Environmental Sciences, Faculty of Science, University of Copenhagen, 1871 Frederiksberg, Denmark,
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Kračun SK, Schückel J, Westereng B, Thygesen LG, Monrad RN, Eijsink VGH, Willats WGT. A new generation of versatile chromogenic substrates for high-throughput analysis of biomass-degrading enzymes. BIOTECHNOLOGY FOR BIOFUELS 2015; 8:70. [PMID: 25969695 PMCID: PMC4428106 DOI: 10.1186/s13068-015-0250-y] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2015] [Accepted: 03/30/2015] [Indexed: 05/02/2023]
Abstract
BACKGROUND Enzymes that degrade or modify polysaccharides are widespread in pro- and eukaryotes and have multiple biological roles and biotechnological applications. Recent advances in genome and secretome sequencing, together with associated bioinformatic tools, have enabled large numbers of carbohydrate-acting enzymes to be putatively identified. However, there is a paucity of methods for rapidly screening the biochemical activities of these enzymes, and this is a serious bottleneck in the development of enzyme-reliant bio-refining processes. RESULTS We have developed a new generation of multi-coloured chromogenic polysaccharide and protein substrates that can be used in cheap, convenient and high-throughput multiplexed assays. In addition, we have produced substrates of biomass materials in which the complexity of plant cell walls is partially maintained. CONCLUSIONS We show that these substrates can be used to screen the activities of glycosyl hydrolases, lytic polysaccharide monooxygenases and proteases and provide insight into substrate availability within biomass. We envisage that the assays we have developed will be used primarily for first-level screening of large numbers of putative carbohydrate-acting enzymes, and the assays have the potential to be incorporated into fully or semi-automated robotic enzyme screening systems.
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Affiliation(s)
- Stjepan Krešimir Kračun
- />Department of Plant and Environmental Sciences, Thorvaldsensvej 40, Frederiksberg, C 1871 Denmark
| | - Julia Schückel
- />Department of Plant and Environmental Sciences, Thorvaldsensvej 40, Frederiksberg, C 1871 Denmark
| | - Bjørge Westereng
- />Department of Plant and Environmental Sciences, Thorvaldsensvej 40, Frederiksberg, C 1871 Denmark
- />Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Chr. M. Falsens vei 1., Aas, 1432 Norway
- />University of Copenhagen, Faculty of Science, Rolighedsvej 23, Frederiksberg, C 1958 Denmark
| | | | | | - Vincent G H Eijsink
- />Department of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Chr. M. Falsens vei 1., Aas, 1432 Norway
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Neumüller KG, de Souza AC, van Rijn JHJ, Streekstra H, Gruppen H, Schols HA. Positional preferences of acetyl esterases from different CE families towards acetylated 4-O-methyl glucuronic acid-substituted xylo-oligosaccharides. BIOTECHNOLOGY FOR BIOFUELS 2015; 8:7. [PMID: 25642285 PMCID: PMC4311478 DOI: 10.1186/s13068-014-0187-6] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2014] [Accepted: 12/15/2014] [Indexed: 05/17/2023]
Abstract
BACKGROUND Acetylation of the xylan backbone restricts the hydrolysis of plant poly- and oligosaccharides by hemicellulolytic enzyme preparations to constituent monosaccharides. The positional preferences and deacetylation efficiencies of acetyl esterases from seven different carbohydrate esterase (CE) families towards different acetylated xylopyranosyl units (Xylp) - as present in 4-O-methyl-glucuronic acid (MeGlcA)-substituted xylo-oligosaccharides (AcUXOS) derived from Eucalyptus globulus - were monitored by (1)H NMR, using common conditions for biofuel production (pH 5.0, 50°C). RESULTS Differences were observed regarding the hydrolysis of 2-O, 3-O, and 2,3-di-O acetylated Xylp and 3-O acetylated Xylp 2-O substituted with MeGlcA. The acetyl esterases tested could be categorized in three groups having activities towards (i) 2-O and 3-O acetylated Xylp, (ii) 2-O, 3-O, and 2,3-di-O acetylated Xylp, and (iii) 2-O, 3-O, and 2,3-di-O acetylated Xylp, as well as 3-O acetylated Xylp 2-O substituted with MeGlcA at the non-reducing end. A high deacetylation efficiency of up to 83% was observed for CE5 and CE1 acetyl esterases. Positional preferences were observed towards 2,3-di-O acetylated Xylp (TeCE1, AnCE5, and OsCE6) or 3-O acetylated Xylp (CtCE4). CONCLUSIONS Different positional preferences, deacetylation efficiencies, and initial deacetylation rates towards 2-O, 3-O, and 2,3-di-O acetylated Xylp and 3-O acetylated Xylp 2-O substituted with MeGlcA were demonstrated for acetyl esterases from different CE families at pH 5.0 and 50°C. The data allow the design of optimal, deacetylating hemicellulolytic enzyme mixtures for the hydrolysis of non-alkaline-pretreated bioenergy feedstocks.
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Affiliation(s)
- Klaus G Neumüller
- />DSM Biotechnology Center, PO Box 1, 2600 MA Delft, The Netherlands
- />Laboratory of Food Chemistry, Wageningen University, Bornse Weilanden 9, 6708 WG Wageningen, The Netherlands
| | | | - Jozef HJ van Rijn
- />DSM Biotechnology Center, PO Box 1, 2600 MA Delft, The Netherlands
| | - Hugo Streekstra
- />DSM Biotechnology Center, PO Box 1, 2600 MA Delft, The Netherlands
| | - Harry Gruppen
- />Laboratory of Food Chemistry, Wageningen University, Bornse Weilanden 9, 6708 WG Wageningen, The Netherlands
| | - Henk A Schols
- />Laboratory of Food Chemistry, Wageningen University, Bornse Weilanden 9, 6708 WG Wageningen, The Netherlands
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Redistribution of acetyl groups on the non-reducing end xylopyranosyl residues and their removal by xylan deacetylases. Appl Microbiol Biotechnol 2014; 99:3865-73. [PMID: 25381188 DOI: 10.1007/s00253-014-6160-2] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Revised: 10/09/2014] [Accepted: 10/12/2014] [Indexed: 01/16/2023]
Abstract
BACKGROUND Monoacetylated xylosyl residues of the main hardwood hemicellulose acetylglucuronoxylan undergo acetyl group migration between positions 2 and 3, and predominantly to position 4 of the non-reducing end xylopyranosyl (NRE-Xylp) residues which are amplified by saccharifying enzymes. On monoacetylated non-reducing end xylopyranosyl (NRE-Xylp) residues of xylooligosaccharides the acetyl group migrates predominantly to position 4 and hinders their hydrolysis by β-xylosidase. METHODS Acetyl migration on the NRE-Xylp residues and their enzymatic deacetylation by various xylan deacetylases was followed by (1)H-NMR spectroscopy and TLC. RESULTS A 5-min heat treatment of 4-nitrophenyl 3-O-acetyl-β-D-xylopyranoside was sufficient to establish equilibrium between monoacetate derivatives acetylated at positions 2, 3 and 4. Rapid acetyl migration along the NRE-Xylp ring at elevated temperature was confirmed in derivatives of methyl β-1,4-xylotrioside (Xyl3Me) monoacetylated solely on the NRE-Xylp residue, the analogues of naturally occurring acetylated xylooligosaccharides. The Xyl3Me monoacetates were used as substrates to study regioselectivity of the NRE-Xylp residue deacetylation by various acetylxylan esterases (AcXEs) of distinct carbohydrate esterase (CE) families. CE1, CE4 and CE6 AcXEs hydrolyzed considerably faster the 2″-O-acetyl derivative than the 3″-O-acetyl derivative. In contrast, the CE16 acetyl esterase preferred to attack the ester bond at position 3 followed by position 4. CONCLUSIONS Redistribution of acetyl group on the NRE-Xylp residues is extremely rapid at elevated temperature and includes the formation of 4-acetate. Regioselectivity of AcXEs and CE16 acetyl esterase on these monoacetates is complementary. GENERAL SIGNIFICANCE The formation of all isomers of acetylated xylosyl residues must be taken into account after a long-term incubation of acetylxylan and acetylated xylooligosaccharides solutions or upon their treatment at elevated temperatures. This phenomenon emphasizes requirement of both types of xylan deacetylases to enable a rapid saccharification of xylooligosaccharides by glycoside hydrolases.
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Busse-Wicher M, Gomes TCF, Tryfona T, Nikolovski N, Stott K, Grantham NJ, Bolam DN, Skaf MS, Dupree P. The pattern of xylan acetylation suggests xylan may interact with cellulose microfibrils as a twofold helical screw in the secondary plant cell wall of Arabidopsis thaliana. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2014; 79:492-506. [PMID: 24889696 PMCID: PMC4140553 DOI: 10.1111/tpj.12575] [Citation(s) in RCA: 174] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2014] [Revised: 05/16/2014] [Accepted: 05/27/2014] [Indexed: 05/17/2023]
Abstract
The interaction between xylan and cellulose microfibrils is important for secondary cell wall properties in vascular plants; however, the molecular arrangement of xylan in the cell wall and the nature of the molecular bonding between the polysaccharides are unknown. In dicots, the xylan backbone of β-(1,4)-linked xylosyl residues is decorated by occasional glucuronic acid, and approximately one-half of the xylosyl residues are O-acetylated at C-2 or C-3. We recently proposed that the even, periodic spacing of GlcA residues in the major domain of dicot xylan might allow the xylan backbone to fold as a twofold helical screw to facilitate alignment along, and stable interaction with, cellulose fibrils; however, such an interaction might be adversely impacted by random acetylation of the xylan backbone. Here, we investigated the arrangement of acetyl residues in Arabidopsis xylan using mass spectrometry and NMR. Alternate xylosyl residues along the backbone are acetylated. Using molecular dynamics simulation, we found that a twofold helical screw conformation of xylan is stable in interactions with both hydrophilic and hydrophobic cellulose faces. Tight docking of xylan on the hydrophilic faces is feasible only for xylan decorated on alternate residues and folded as a twofold helical screw. The findings suggest an explanation for the importance of acetylation for xylan-cellulose interactions, and also have implications for our understanding of cell wall molecular architecture and properties, and biological degradation by pathogens and fungi. They will also impact strategies to improve lignocellulose processing for biorefining and bioenergy.
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Affiliation(s)
- Marta Busse-Wicher
- Department of Biochemistry, University Of CambridgeTennis Court Road, Cambridge, CB2 1QW, UK
| | - Thiago C F Gomes
- Institute of Chemistry, University of Campinas-UNICAMPPO Box 6154, Campinas, SP, 13084-862, Brazil
| | - Theodora Tryfona
- Department of Biochemistry, University Of CambridgeTennis Court Road, Cambridge, CB2 1QW, UK
| | - Nino Nikolovski
- Department of Biochemistry, University Of CambridgeTennis Court Road, Cambridge, CB2 1QW, UK
| | - Katherine Stott
- Department of Biochemistry, University Of CambridgeTennis Court Road, Cambridge, CB2 1QW, UK
| | - Nicholas J Grantham
- Department of Biochemistry, University Of CambridgeTennis Court Road, Cambridge, CB2 1QW, UK
| | - David N Bolam
- Institute for Cell and Molecular Biosciences, The Medical School, Newcastle UniversityNewcastle upon Tyne, NE2 4HH, UK
| | - Munir S Skaf
- Institute of Chemistry, University of Campinas-UNICAMPPO Box 6154, Campinas, SP, 13084-862, Brazil
| | - Paul Dupree
- Department of Biochemistry, University Of CambridgeTennis Court Road, Cambridge, CB2 1QW, UK
- *For correspondence (e-mail )
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Neumüller KG, Streekstra H, Gruppen H, Schols HA. Trichoderma longibrachiatum acetyl xylan esterase 1 enhances hemicellulolytic preparations to degrade corn silage polysaccharides. BIORESOURCE TECHNOLOGY 2014; 163:64-73. [PMID: 24787318 DOI: 10.1016/j.biortech.2014.04.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2014] [Revised: 03/31/2014] [Accepted: 04/02/2014] [Indexed: 05/11/2023]
Abstract
Supplementation of a Trichoderma longibrachiatum preparation to an industrial Aspergillus niger/Talaromyces emersonii enzyme mixture demonstrated synergy for the saccharification of corn silage water-unextractable solids (WUS). Sub-fractions of the crude T. longibrachiatum preparation obtained after chromatography were analyzed regarding their hydrolytic activity. An acetyl xylan esterase 1 [Axe1, carbohydrate esterase (CE) family 5]-enriched sub-fraction closely mimicked the hydrolytic gain as obtained by supplementation of the complete, crude enzyme mixture (increase of 50%, 62% and 29% for Xyl, Ara and Glc, respectively). The acetic acid released from model polysaccharides (WUS) and oligosaccharides [neutral (AcXOS) and acidic (AcUXOS) xylo-oligosaccharides] by Axe1 was two and up to six times higher compared to the acetic acid released by acetyl xylan esterase A (AxeA, CE 1). Characterization of Axe1 treated AcXOS and AcUXOS revealed deacetylation of oligosaccharides that were not deacetylated by AxeA or the A. niger/T. emersonii preparation.
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Affiliation(s)
- K G Neumüller
- DSM Biotechnology Center, PO Box 1, 2600 MA Delft, The Netherlands; Laboratory of Food Chemistry, Wageningen University, Bornse Weilanden 9, 6708 WG Wageningen, The Netherlands
| | - H Streekstra
- DSM Biotechnology Center, PO Box 1, 2600 MA Delft, The Netherlands
| | - H Gruppen
- Laboratory of Food Chemistry, Wageningen University, Bornse Weilanden 9, 6708 WG Wageningen, The Netherlands
| | - H A Schols
- Laboratory of Food Chemistry, Wageningen University, Bornse Weilanden 9, 6708 WG Wageningen, The Netherlands.
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Koutaniemi S, van Gool MP, Juvonen M, Jokela J, Hinz SW, Schols HA, Tenkanen M. Distinct roles of carbohydrate esterase family CE16 acetyl esterases and polymer-acting acetyl xylan esterases in xylan deacetylation. J Biotechnol 2013; 168:684-92. [PMID: 24140638 DOI: 10.1016/j.jbiotec.2013.10.009] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Revised: 10/02/2013] [Accepted: 10/07/2013] [Indexed: 10/26/2022]
Abstract
Mass spectrometric analysis was used to compare the roles of two acetyl esterases (AE, carbohydrate esterase family CE16) and three acetyl xylan esterases (AXE, families CE1 and CE5) in deacetylation of natural substrates, neutral (linear) and 4-O-methyl glucuronic acid (MeGlcA) substituted xylooligosaccharides (XOS). AEs were similarly restricted in their action and apparently removed in most cases only one acetyl group from the non-reducing end of XOS, acting as exo-deacetylases. In contrast, AXEs completely deacetylated longer neutral XOS but had difficulties with the shorter ones. Complete deacetylation of neutral XOS was obtained after the combined action of AEs and AXEs. MeGlcA substituents partially restricted the action of both types of esterases and the remaining acidic XOS were mainly substituted with one MeGlcA and one acetyl group, supposedly on the same xylopyranosyl residue. These resisting structures were degraded to great extent only after inclusion of α-glucuronidase, which acted with the esterases in a synergistic manner. When used together with xylan backbone degrading endoxylanase and β-xylosidase, both AE and AXE enhanced the hydrolysis of complex XOS equally.
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Affiliation(s)
- S Koutaniemi
- Department of Food and Environmental Chemistry, University of Helsinki, P.O. Box 27, 00014 Helsinki, Finland.
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Biely P, Cziszárová M, Agger JW, Li XL, Puchart V, Vršanská M, Eijsink VGH, Westereng B. Trichoderma reesei CE16 acetyl esterase and its role in enzymatic degradation of acetylated hemicellulose. Biochim Biophys Acta Gen Subj 2013; 1840:516-25. [PMID: 24128930 DOI: 10.1016/j.bbagen.2013.10.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Revised: 10/04/2013] [Accepted: 10/07/2013] [Indexed: 10/26/2022]
Abstract
BACKGROUND Trichoderma reesei CE16 acetyl esterase (AcE) is a component of the plant cell wall degrading system of the fungus. The enzyme behaves as an exo-acting deacetylase removing acetyl groups from non-reducing end sugar residues. METHODS In this work we demonstrate this exo-deacetylating activity on natural acetylated xylooligosaccharides using MALDI ToF MS. RESULTS The combined action of GH10 xylanase and acetylxylan esterases (AcXEs) leads to formation of neutral and acidic xylooligosaccharides with a few resistant acetyl groups mainly at their non-reducing ends. We show here that these acetyl groups serve as targets for TrCE16 AcE. The most prominent target is the 3-O-acetyl group at the non-reducing terminal Xylp residues of linear neutral xylooligosaccharides or on aldouronic acids carrying MeGlcA at the non-reducing terminus. Deacetylation of the non-reducing end sugar may involve migration of acetyl groups to position 4, which also serves as substrate of the TrCE16 esterase. CONCLUSION Concerted action of CtGH10 xylanase, an AcXE and TrCE16 AcE resulted in close to complete deacetylation of neutral xylooligosaccharides, whereas substitution with MeGlcA prevents removal of acetyl groups from only a small fraction of the aldouronic acids. Experiments with diacetyl derivatives of methyl β-d-xylopyranoside confirmed that the best substrate of TrCE16 AcE is 3-O-acetylated Xylp residue followed by 4-O-acetylated Xylp residue with a free vicinal hydroxyl group. GENERAL SIGNIFICANCE This study shows that CE16 acetyl esterases are crucial enzymes to achieve complete deacetylation and, consequently, complete the saccharification of acetylated xylans by xylanases, which is an important task of current biotechnology.
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Affiliation(s)
- Peter Biely
- Institute of Chemistry, Center for Glycomics, Slovak Academy of Sciences, Dubravska cesta 9, 84538 Bratislava, Slovakia.
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