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Tong L, Li Y, Lou X, Wang B, Jin C, Fang W. Powerful cell wall biomass degradation enzymatic system from saprotrophic Aspergillus fumigatus. Cell Surf 2024; 11:100126. [PMID: 38827922 PMCID: PMC11143905 DOI: 10.1016/j.tcsw.2024.100126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2024] [Revised: 05/08/2024] [Accepted: 05/15/2024] [Indexed: 06/05/2024] Open
Abstract
Cell wall biomass, Earth's most abundant natural resource, holds significant potential for sustainable biofuel production. Composed of cellulose, hemicellulose, lignin, pectin, and other polymers, the plant cell wall provides essential structural support to diverse organisms in nature. In contrast, non-plant species like insects, crustaceans, and fungi rely on chitin as their primary structural polysaccharide. The saprophytic fungus Aspergillus fumigatus has been widely recognized for its adaptability to various environmental conditions. It achieves this by secreting different cell wall biomass degradation enzymes to obtain essential nutrients. This review compiles a comprehensive collection of cell wall degradation enzymes derived from A. fumigatus, including cellulases, hemicellulases, various chitin degradation enzymes, and other polymer degradation enzymes. Notably, these enzymes exhibit biochemical characteristics such as temperature tolerance or acid adaptability, indicating their potential applications across a spectrum of industries.
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Affiliation(s)
- Lige Tong
- National Key Laboratory of Non-food Biomass Energy Technology, Institute of Biological Sciences and Technology, Guangxi Academy of Sciences, Nanning, Guangxi, China
| | - Yunaying Li
- National Key Laboratory of Non-food Biomass Energy Technology, Institute of Biological Sciences and Technology, Guangxi Academy of Sciences, Nanning, Guangxi, China
- College of Life Sciences, Hebei Innovation Center for Bioengineering and Biotechnology, Institute of Life Sciences and Green Development, Baoding, Hebei, China
| | - Xinke Lou
- National Key Laboratory of Non-food Biomass Energy Technology, Institute of Biological Sciences and Technology, Guangxi Academy of Sciences, Nanning, Guangxi, China
- College of Life Sciences, Hebei Innovation Center for Bioengineering and Biotechnology, Institute of Life Sciences and Green Development, Baoding, Hebei, China
| | - Bin Wang
- National Key Laboratory of Non-food Biomass Energy Technology, Institute of Biological Sciences and Technology, Guangxi Academy of Sciences, Nanning, Guangxi, China
| | - Cheng Jin
- National Key Laboratory of Non-food Biomass Energy Technology, Institute of Biological Sciences and Technology, Guangxi Academy of Sciences, Nanning, Guangxi, China
- State Key Laboratory of Mycology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China
| | - Wenxia Fang
- National Key Laboratory of Non-food Biomass Energy Technology, Institute of Biological Sciences and Technology, Guangxi Academy of Sciences, Nanning, Guangxi, China
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Unraveling Synergism between Various GH Family Xylanases and Debranching Enzymes during Hetero-Xylan Degradation. Molecules 2021; 26:molecules26226770. [PMID: 34833862 PMCID: PMC8618192 DOI: 10.3390/molecules26226770] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 10/15/2021] [Accepted: 10/27/2021] [Indexed: 11/20/2022] Open
Abstract
Enzymes classified with the same Enzyme Commission (EC) that are allotted in different glycoside hydrolase (GH) families can display different mechanisms of action and substrate specificities. Therefore, the combination of different enzyme classes may not yield synergism during biomass hydrolysis, as the GH family allocation of the enzymes influences their behavior. As a result, it is important to understand which GH family combinations are compatible to gain knowledge on how to efficiently depolymerize biomass into fermentable sugars. We evaluated GH10 (Xyn10D and XT6) and GH11 (XynA and Xyn2A) β-xylanase performance alone and in combination with various GH family α-l-arabinofuranosidases (GH43 AXH-d and GH51 Abf51A) and α-d-glucuronidases (GH4 Agu4B and GH67 AguA) during xylan depolymerization. No synergistic enhancement in reducing sugar, xylose and glucuronic acid released from beechwood xylan was observed when xylanases were supplemented with either one of the glucuronidases, except between Xyn2A and AguA (1.1-fold reducing sugar increase). However, overall sugar release was significantly improved (≥1.1-fold reducing sugar increase) when xylanases were supplemented with either one of the arabinofuranosidases during wheat arabinoxylan degradation. Synergism appeared to result from the xylanases liberating xylo-oligomers, which are the preferred substrates of the terminal arabinofuranosyl-substituent debranching enzyme, Abf51A, allowing the exolytic β-xylosidase, SXA, to have access to the generated unbranched xylo-oligomers. Here, it was shown that arabinofuranosidases are key enzymes in the efficient saccharification of hetero-xylan into xylose. This study demonstrated that consideration of GH family affiliations of the carbohydrate-active enzymes (CAZymes) used to formulate synergistic enzyme cocktails is crucial for achieving efficient biomass saccharification.
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Molecular modification, structural characterization, and biological activity of xylans. Carbohydr Polym 2021; 269:118248. [PMID: 34294285 DOI: 10.1016/j.carbpol.2021.118248] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2020] [Revised: 05/21/2021] [Accepted: 05/23/2021] [Indexed: 12/17/2022]
Abstract
The differences in the source and structure of xylans make them have various biological activities. However, due to their inherent structural limitations, the various biological activities of xylans are far lower than those of commercial drugs. Currently, several types of molecular modification methods have been developed to address these limitations, and many derivatives with specific biological activity have been obtained. Further research on structural characteristics, structure-activity relationship and mechanism of action is of great significance for the development of xylan derivatives. Therefore, the major molecular modification methods of xylans are introduced in this paper, and the primary structure and conformation characteristics of xylans and their derivatives are summarized. In addition, the biological activity and structure-activity relationship of the modified xylans are also discussed.
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Tamayo-Ordóñez MC, Contreras-Esquivel JC, Ayil-Gutiérrez BA, De la Cruz-Arguijo EA, Tamayo-Ordóñez FA, Ríos-González LJ, Tamayo-Ordóñez YJ. Interspecific evolutionary relationships of alpha-glucuronidase in the genus Aspergillus. Fungal Biol 2021; 125:560-575. [PMID: 34140152 DOI: 10.1016/j.funbio.2021.02.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2020] [Revised: 02/05/2021] [Accepted: 02/21/2021] [Indexed: 12/15/2022]
Abstract
The increased availability and production of lignocellulosic agroindustrial wastes has originated proposals for their use as raw material to obtain biofuels (ethanol and biodiesel) or derived products. However, for biomass generated from lignocellulosic residues to be successfully degraded, in most cases it requires a physical (thermal), chemical, or enzymatic pretreatment before the application of microbial or enzymatic fermentation technologies (biocatalysis). In the context of enzymatic technologies, fungi have demonstrated to produce enzymes capable of degrading polysaccharides like cellulose, hemicelluloses and pectin. Because of this ability for degrading lignocellulosic material, researchers are making efforts to isolate and identify fungal enzymes that could have a better activity for the degradation of plant cell walls and agroindustrial biomass. We performed an in silico analysis of alpha-glucoronidase in 82 accessions of the genus Aspergillus. The constructed dendrograms of amino acid sequences defined the formation of 6 groups (I, II, III, IV, V, and VI), which demonstrates the high diversity of the enzyme. Despite this ample divergence between enzyme groups, our 3D structure modeling showed both conservation and differences in amino acid residues participating in enzyme-substrate binding, which indicates the possibility that some enzymes are functionally specialized for the specific degradation of a substrate depending on the genetics of each species in the genus and the condition of the habitat where they evolved. The identification of alpha-glucuronidase isoenzymes would allow future use of genetic engineering and biocatalysis technologies aimed at specific production of the enzyme for its use in biotransformation.
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Affiliation(s)
- M C Tamayo-Ordóñez
- Laboratorio de Ingeniería Genética, Departamento de Biotecnología, Facultad de Ciencias Químicas, Universidad Autónoma de Coahuila, Ing J. Cárdenas Valdez S/N, República, 25280, Saltillo, Coah, Mexico
| | - J C Contreras-Esquivel
- Laboratorio de Glicobiotecnologia Aplicada, Departamento de Ciencia y Tecnología de Alimentos, Facultad de Ciencias Químicas, Universidad Autónoma de Coahuila, Ing. J. Cárdenas Valdez S/N, República, 25280, Saltillo, Coah, Mexico
| | - B A Ayil-Gutiérrez
- CONACYT- Centro de Biotecnología Genómica, Instituto Politécnico Nacional, Biotecnologia Vegetal. Blvd. del Maestro, s/n, Esq. Elías Piña, Reynosa, 88710, Mexico
| | - E A De la Cruz-Arguijo
- Centro de Biotecnología Genómica, Instituto Politécnico Nacional, Blvd. del Maestro, s/n, Esq. Elías Piña, Reynosa, 88710, Mexico
| | - F A Tamayo-Ordóñez
- Facultad de Química, Universidad Autónoma del Carmen, Calle 56 No. 4 por Av. Concordia, Campus Principal, 24180, Ciudad del Carmen, Campeche, Mexico
| | - L J Ríos-González
- Departamento de Biotecnología, Facultad de Ciencias Químicas, Universidad Autónoma de Coahuila, Ing Cárdenas Valdez S/N, República, 25280, Saltillo, Coah, Mexico
| | - Y J Tamayo-Ordóñez
- Estancia Posdoctoral Nacional-CONACyT, Posgrado en Ciencia y Tecnología de Alimentos, Facultad de Ciencias Químicas, Universidad Autónoma de Coahuila, Ing J. Cardenas Valdez S/N, República, 25280, Saltillo, Coah, Mexico.
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Santibáñez L, Henríquez C, Corro-Tejeda R, Bernal S, Armijo B, Salazar O. Xylooligosaccharides from lignocellulosic biomass: A comprehensive review. Carbohydr Polym 2021; 251:117118. [DOI: 10.1016/j.carbpol.2020.117118] [Citation(s) in RCA: 78] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2020] [Revised: 08/22/2020] [Accepted: 09/04/2020] [Indexed: 02/04/2023]
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Malgas S, Mafa MS, Mkabayi L, Pletschke BI. A mini review of xylanolytic enzymes with regards to their synergistic interactions during hetero-xylan degradation. World J Microbiol Biotechnol 2019; 35:187. [PMID: 31728656 DOI: 10.1007/s11274-019-2765-z] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Accepted: 11/06/2019] [Indexed: 10/25/2022]
Abstract
This review examines the recent models describing the mode of action of various xylanolytic enzymes and how these enzymes can be applied (sequentially or simultaneously) with their distinctive roles in mind to achieve efficient xylan degradation. With respect to homeosynergy, synergism appears to be as a result of β-xylanase and/or oligosaccharide reducing-end β-xylanase liberating xylo-oligomers (XOS) that are preferred substrates of the processive β-xylosidase. With regards to hetero-synergism, two cross relationships appear to exist and seem to be the reason for synergism between the enzymes during xylan degradation. These cross relations are the debranching enzymes such as α-glucuronidase or side-chain cleaving enzymes such as carbohydrate esterases (CE) removing decorations that would have hindered back-bone-cleaving enzymes, while backbone-cleaving-enzymes liberate XOS that are preferred substrates of the debranching and side-chain-cleaving enzymes. This interaction is demonstrated by high yields in co-production of xylan substituents such as arabinose, glucuronic acid and ferulic acid, and XOS. Finally, lytic polysaccharide monooxygenases (LPMO) have also been implicated in boosting whole lignocellulosic biomass or insoluble xylan degradation by glycoside hydrolases (GH) by possibly disrupting entangled xylan residues. Since it has been observed that the same enzyme (same Enzyme Commission, EC, classification) from different GH or CE and/or AA families can display different synergistic interactions with other enzymes due to different substrate specificities and properties, in this review, we propose an approach of enzyme selection (and mode of application thereof) during xylan degradation, as this can improve the economic viability of the degradation of xylan for producing precursors of value added products.
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Affiliation(s)
- Samkelo Malgas
- Enzyme Science Programme (ESP), Department of Biochemistry and Microbiology, Rhodes University, Grahamstown, Eastern Cape, 6140, South Africa
| | - Mpho S Mafa
- Enzyme Science Programme (ESP), Department of Biochemistry and Microbiology, Rhodes University, Grahamstown, Eastern Cape, 6140, South Africa.,Protein Structure-Function Research Unit (PSFRU), School of Molecular and Cell Biology, Wits University, Johannesburg, Gauteng, 2000, South Africa
| | - Lithalethu Mkabayi
- Enzyme Science Programme (ESP), Department of Biochemistry and Microbiology, Rhodes University, Grahamstown, Eastern Cape, 6140, South Africa
| | - Brett I Pletschke
- Enzyme Science Programme (ESP), Department of Biochemistry and Microbiology, Rhodes University, Grahamstown, Eastern Cape, 6140, South Africa.
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The effect of an oligosaccharide reducing-end xylanase, BhRex8A, on the synergistic degradation of xylan backbones by an optimised xylanolytic enzyme cocktail. Enzyme Microb Technol 2019; 122:74-81. [DOI: 10.1016/j.enzmictec.2018.12.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Revised: 12/14/2018] [Accepted: 12/18/2018] [Indexed: 12/19/2022]
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Yagi H, Maehara T, Tanaka T, Takehara R, Teramoto K, Yaoi K, Kaneko S. 4- O-Methyl Modifications of Glucuronic Acids in Xylans Are Indispensable for Substrate Discrimination by GH67 α-Glucuronidase from Bacillus halodurans C-125. J Appl Glycosci (1999) 2017; 64:115-121. [PMID: 34354504 PMCID: PMC8056927 DOI: 10.5458/jag.jag.jag-2017_016] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 10/18/2017] [Indexed: 10/29/2022] Open
Abstract
A GH67 α-glucuronidase gene derived from Bacillus halodurans C-125 was expressed in E. coli to obtain a recombinant enzyme (BhGlcA67). Using the purified enzyme, the enzymatic properties and substrate specificities of the enzyme were investigated. BhGlcA67 showed maximum activity at pH 5.4 and 45 °C. When BhGlcA67 was incubated with birchwood, oat spelts, and cotton seed xylan, the enzyme did not release any glucuronic acid or 4-O-methyl-glucuronic acid from these substrates. BhGlcA67 acted only on 4-O-methyl-α-D-glucuronopyranosyl-(1→2)-β-D-xylopyranosyl-(1→4)-β-D-xylopyranosyl-(1→4)-β-D-xylopyranose (MeGlcA3Xyl3), which has a glucuronic acid side chain with a 4-O-methyl group located at its non-reducing end, but did not on β-D-xylopyranosyl-(1→4)-[4-O-methyl-α-D-glucuronopyranosyl-(l→2)]-β-D-xylopyranosyl-(1→4)-β-D-xylopyranosyl-(1→4)-β-D-xylop- yranose (MeGlcA3Xyl4) and α-D-glucuronopyranosyl-(l→2)-β-D-xylopyranosyl-(1→4)-β-D-xylopyranosyl-(1→4)-β-D-xylopyranose (GlcA3Xyl3). The environment for recognizing the 4-O-methyl group of glucuronic acid was observed in all the crystal structures of reported GH67 glucuronidases, and the amino acids for discriminating the 4-O-methyl group of glucuronic acid were widely conserved in the primary sequences of the GH67 family, suggesting that the 4-O-methyl group is critical for the activities of the GH67 family.
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Affiliation(s)
- Haruka Yagi
- 1 Department of Subtropical Biochemistry and Biotechnology, Faculty of Agriculture, University of the Ryukyus
| | - Tomoko Maehara
- 2 Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST)
| | - Tsuyoshi Tanaka
- 1 Department of Subtropical Biochemistry and Biotechnology, Faculty of Agriculture, University of the Ryukyus.,3 The United Graduate School of Agricultural Sciences, Kagoshima University
| | - Ryo Takehara
- 1 Department of Subtropical Biochemistry and Biotechnology, Faculty of Agriculture, University of the Ryukyus
| | - Koji Teramoto
- 1 Department of Subtropical Biochemistry and Biotechnology, Faculty of Agriculture, University of the Ryukyus
| | - Katsuro Yaoi
- 2 Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST)
| | - Satoshi Kaneko
- 1 Department of Subtropical Biochemistry and Biotechnology, Faculty of Agriculture, University of the Ryukyus
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Wang W, Yan R, Nocek BP, Vuong TV, Di Leo R, Xu X, Cui H, Gatenholm P, Toriz G, Tenkanen M, Savchenko A, Master ER. Biochemical and Structural Characterization of a Five-domain GH115 α-Glucuronidase from the Marine Bacterium Saccharophagus degradans 2-40T. J Biol Chem 2016; 291:14120-14133. [PMID: 27129264 DOI: 10.1074/jbc.m115.702944] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Indexed: 01/01/2023] Open
Abstract
Glucuronic acid (GlcAp) and/or methylglucuronic acid (MeGlcAp) decorate the major forms of xylan in hardwood and coniferous softwoods as well as many cereal grains. Accordingly, the complete utilization of glucuronoxylans or conversion to sugar precursors requires the action of main chain xylanases as well as α-glucuronidases that release the α- (1→2)-linked (Me)GlcAp side groups. Herein, a family GH115 enzymefrom the marine bacterium Saccharophagus degradans 2-40(T), SdeAgu115A, demonstrated activity toward glucuronoxylan and oligomers thereof with preference toward MeGlcAp linked to internal xylopyranosyl residues. Unique biochemical characteristics of NaCl activation were also observed. The crystal structure of SdeAgu115A revealed a five-domain architecture, with an additional insertion C(+) domain that had significant impact on the domain arrangement of SdeAgu115A monomer and its dimerization. The participation of domain C(+) in substrate binding was supported by reduced substrate inhibition upon introducing W773A, W689A, and F696A substitutions within this domain. In addition to Asp-335, the catalytic essentiality of Glu-216 was revealed by site-specific mutagenesis. A primary sequence analysis suggested that the SdeAgu115A architecture is shared by more than half of GH115 members, thus defining a distinct archetype for GH115 enzymes.
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Affiliation(s)
- Weijun Wang
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario M5S 3E5, Canada
| | - Ruoyu Yan
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario M5S 3E5, Canada
| | - Boguslaw P Nocek
- Structural Biology Center, Biosciences Division, Argonne National Laboratory, Argonne, Illinois 60439
| | - Thu V Vuong
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario M5S 3E5, Canada
| | - Rosa Di Leo
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario M5S 3E5, Canada
| | - Xiaohui Xu
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario M5S 3E5, Canada
| | - Hong Cui
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario M5S 3E5, Canada
| | - Paul Gatenholm
- Department of Chemistry and Chemical Engineering, Wallenberg Wood Science Center and Biopolymer Technology, Chalmers University of Technology, Kemivägen 4, Gothenburg 412 96, Sweden
| | - Guillermo Toriz
- Department of Chemistry and Chemical Engineering, Wallenberg Wood Science Center and Biopolymer Technology, Chalmers University of Technology, Kemivägen 4, Gothenburg 412 96, Sweden,; Department of Wood, Cellulose and Paper Research, University of Guadalajara, Guadalajara 44100, Mexico
| | - Maija Tenkanen
- Department of Food and Environmental Sciences, University of Helsinki, P.O. Box 27, Helsinki 00014, Finland
| | - Alexei Savchenko
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario M5S 3E5, Canada,.
| | - Emma R Master
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, 200 College Street, Toronto, Ontario M5S 3E5, Canada,.
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Pérez R, Eyzaguirre J. Aspergillus fumigatus Produces Two Arabinofuranosidases From Glycosyl Hydrolase Family 62: Comparative Properties of the Recombinant Enzymes. Appl Biochem Biotechnol 2016; 179:143-54. [DOI: 10.1007/s12010-016-1984-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2015] [Accepted: 01/07/2016] [Indexed: 10/22/2022]
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Martínez PM, Appeldoorn MM, Gruppen H, Kabel MA. The two Rasamsonia emersonii α-glucuronidases, ReGH67 and ReGH115, show a different mode-of-action towards glucuronoxylan and glucuronoxylo-oligosaccharides. BIOTECHNOLOGY FOR BIOFUELS 2016; 9:105. [PMID: 27195020 PMCID: PMC4870768 DOI: 10.1186/s13068-016-0519-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Accepted: 05/05/2016] [Indexed: 05/11/2023]
Abstract
BACKGROUND The production of biofuels and biochemicals from grass-type plant biomass requires a complete utilisation of the plant cellulose and hemicellulosic xylan via enzymatic degradation to their constituent monosaccharides. Generally, physical and/or thermochemical pretreatments are performed to enable access for the subsequent added carbohydrate-degrading enzymes. Nevertheless, partly substituted xylan structures remain after pretreatment, in particular the ones substituted with (4-O-methyl-)glucuronic acids (UAme). Hence, α-glucuronidases play an important role in the degradation of UAmexylan structures facilitating the complete utilisation of plant biomass. The characterisation of α-glucuronidases is a necessity to find the right enzymes to improve degradation of recalcitrant UAmexylan structures. RESULTS The mode-of-action of two α-glucuronidases was demonstrated, both obtained from the fungus Rasamsonia emersonii; one belonging to the glycoside hydrolase (GH) family 67 (ReGH67) and the other to GH115 (ReGH115). Both enzymes functioned optimal at around pH 4 and 70 °C. ReGH67 was able to release UAme from UAme-substituted xylo-oligosaccharides (UAmeXOS), but only the UAme linked to the non-reducing end xylosyl residue was cleaved. In particular, in a mixture of oligosaccharides, UAmeXOS having a degree of polymerisation (DP) of two were hydrolysed to a further extent than longer UAmeXOS (DP 3-4). On the contrary, ReGH115 was able to release UAme from both polymeric UAmexylan and UAmeXOS. ReGH115 cleaved UAme from both internal and non-reducing end xylosyl residues, with the exception of UAme attached to the non-reducing end of a xylotriose oligosaccharide. CONCLUSION In this research, and for the first time, we define the mode-of-action of two α-glucuronidases from two different GH families both from the ascomycete R. emersonii. To date, only four α-glucuronidases classified in GH115 are characterised. ReGH67 showed limited substrate specificity towards only UAmeXOS, cleaving UAme only when attached to the non-reducing end xylosyl residue. ReGH115 was much less substrate specific compared to ReGH67, because UAme was released from both polymeric UAmexylan and UAmeXOS, from both internal and non-reducing end xylosyl residues. The characterisation of the mode-of-action of these two α-glucuronidases helps understand how R. emersonii attacks UAmexylan in plant biomass and the knowledge presented is valuable to improve enzyme cocktails for biorefinery applications.
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Affiliation(s)
- Patricia Murciano Martínez
- />Laboratory of Food Chemistry, Wageningen University, Bornse Weilanden 9, 6708 WG Wageningen, The Netherlands
| | - Maaike M. Appeldoorn
- />DSM Biotechnology Center, Alexander Fleminglaan 1, 2613 AX Delft, The Netherlands
| | - Harry Gruppen
- />Laboratory of Food Chemistry, Wageningen University, Bornse Weilanden 9, 6708 WG Wageningen, The Netherlands
| | - Mirjam A. Kabel
- />Laboratory of Food Chemistry, Wageningen University, Bornse Weilanden 9, 6708 WG Wageningen, The Netherlands
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