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Liu Y, Li T, Zhu H, Cao L, Liang L, Liu D, Shen Q. Methionine inducing carbohydrate esterase secretion of Trichoderma harzianum enhances the accessibility of substrate glycosidic bonds. Microb Cell Fact 2024; 23:120. [PMID: 38664812 PMCID: PMC11046756 DOI: 10.1186/s12934-024-02394-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2024] [Accepted: 04/16/2024] [Indexed: 04/28/2024] Open
Abstract
BACKGROUND The conversion of plant biomass into biochemicals is a promising way to alleviate energy shortage, which depends on efficient microbial saccharification and cellular metabolism. Trichoderma spp. have plentiful CAZymes systems that can utilize all-components of lignocellulose. Acetylation of polysaccharides causes nanostructure densification and hydrophobicity enhancement, which is an obstacle for glycoside hydrolases to hydrolyze glycosidic bonds. The improvement of deacetylation ability can effectively release the potential for polysaccharide degradation. RESULTS Ammonium sulfate addition facilitated the deacetylation of xylan by inducing the up-regulation of multiple carbohydrate esterases (CE3/CE4/CE15/CE16) of Trichoderma harzianum. Mainly, the pathway of ammonium-sulfate's cellular assimilates inducing up-regulation of the deacetylase gene (Thce3) was revealed. The intracellular metabolite changes were revealed through metabonomic analysis. Whole genome bisulfite sequencing identified a novel differentially methylated region (DMR) that existed in the ThgsfR2 promoter, and the DMR was closely related to lignocellulolytic response. ThGsfR2 was identified as a negative regulatory factor of Thce3, and methylation in ThgsfR2 promoter released the expression of Thce3. The up-regulation of CEs facilitated the substrate deacetylation. CONCLUSION Ammonium sulfate increased the polysaccharide deacetylation capacity by inducing the up-regulation of multiple carbohydrate esterases of T. harzianum, which removed the spatial barrier of the glycosidic bond and improved hydrophilicity, and ultimately increased the accessibility of glycosidic bond to glycoside hydrolases.
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Affiliation(s)
- Yang Liu
- Key Lab of Organic-Based Fertilizers of China and Jiangsu Provincial Key Lab for Solid Organic Waste Utilization, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China
- College of Resource and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China
| | - Tuo Li
- Key Lab of Organic-Based Fertilizers of China and Jiangsu Provincial Key Lab for Solid Organic Waste Utilization, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China
- College of Resource and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China
| | - Han Zhu
- Key Lab of Organic-Based Fertilizers of China and Jiangsu Provincial Key Lab for Solid Organic Waste Utilization, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China
- College of Resource and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China
| | - Linhua Cao
- Key Lab of Organic-Based Fertilizers of China and Jiangsu Provincial Key Lab for Solid Organic Waste Utilization, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China
- College of Resource and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China
| | - Lebin Liang
- Key Lab of Organic-Based Fertilizers of China and Jiangsu Provincial Key Lab for Solid Organic Waste Utilization, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China
- College of Resource and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China
| | - Dongyang Liu
- Key Lab of Organic-Based Fertilizers of China and Jiangsu Provincial Key Lab for Solid Organic Waste Utilization, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China.
- College of Resource and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China.
| | - Qirong Shen
- Key Lab of Organic-Based Fertilizers of China and Jiangsu Provincial Key Lab for Solid Organic Waste Utilization, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China
- College of Resource and Environmental Sciences, Nanjing Agricultural University, Nanjing, 210095, People's Republic of China
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Mafa MS, Malgas S. Towards an understanding of the enzymatic degradation of complex plant mannan structures. World J Microbiol Biotechnol 2023; 39:302. [PMID: 37688610 PMCID: PMC10492685 DOI: 10.1007/s11274-023-03753-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Accepted: 09/04/2023] [Indexed: 09/11/2023]
Abstract
Plant cell walls are composed of a heterogeneous mixture of polysaccharides that require several different enzymes to degrade. These enzymes are important for a variety of biotechnological processes, from biofuel production to food processing. Several classical mannanolytic enzyme functions of glycoside hydrolases (GH), such as β-mannanase, β-mannosidase and α-galactosidase activities, are helpful for efficient mannan hydrolysis. In this light, we bring three enzymes into the model of mannan degradation that have received little or no attention. By linking their three-dimensional structures and substrate specificities, we have predicted the interactions and cooperativity of these novel enzymes with classical mannanolytic enzymes for efficient mannan hydrolysis. The novel exo-β-1,4-mannobiohydrolases are indispensable for the production of mannobiose from the terminal ends of mannans, this product being the preferred product for short-chain mannooligosaccharides (MOS)-specific β-mannosidases. Second, the side-chain cleaving enzymes, acetyl mannan esterases (AcME), remove acetyl decorations on mannan that would have hindered backbone cleaving enzymes, while the backbone cleaving enzymes liberate MOS, which are preferred substrates of the debranching and sidechain cleaving enzymes. The nonhydrolytic expansins and swollenins disrupt the crystalline regions of the biomass, improving their accessibility for AcME and GH activities. Finally, lytic polysaccharide monooxygenases have also been implicated in promoting the degradation of lignocellulosic biomass or mannan degradation by classical mannanolytic enzymes, possibly by disrupting adsorbed mannan residues. Modelling effective enzymatic mannan degradation has implications for improving the saccharification of biomass for the synthesis of value-added and upcycling of lignocellulosic wastes.
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Affiliation(s)
- Mpho Stephen Mafa
- Carbohydrates and Enzymology Laboratory (CHEM-LAB), Department of Plant Sciences, University of the Free State, Bloemfontein, 9300 South Africa
| | - Samkelo Malgas
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Hatfield, 0028 South Africa
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Bella M, Poláková M, Puchart V. Deacetylation of arabinosylated xylosyl residues related to plant xylan: significant differences between xylan deacetylases classified into various carbohydrate esterase families. Chembiochem 2023; 24:e202200743. [PMID: 36779690 DOI: 10.1002/cbic.202200743] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Revised: 02/10/2023] [Accepted: 02/13/2023] [Indexed: 02/14/2023]
Abstract
A chemical synthesis of two novel phenyl glycosides of trisaccharides related to acetylarabinoxylan is described. The trisaccharides bear acetyl and arabinofuranosyl moieties at the non-reducing-end xylopyranosyl residue, which is substituted at positions 2 and 3. Both compounds were treated with various xylan deacetylases classified in different carbohydrate esterase (CE) families and significant differences between the families were found. While the arabinosylation hampers deacetylation by CE2-CE5 and CE12 family members, both epitopes are deesterified by CE1 and in particular CE6 enzymes. The 3-O-acetylated 2-O-arabinosylated compound is also processed by CE7 and majority of CE16 esterases, but not by a hitherto non-classified Flavobacterium johnsoniae acetylxylan esterase. The data suggests that a slow deesterification of the 2-O-acetylated 3-O-arabinosylated compound may be due to the acetyl group migration to position 4 followed by deacetylation of this position.
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Affiliation(s)
- Maroš Bella
- Institute of Chemistry Slovak Academy of Sciences: Chemicky ustav Slovenskej akademie vied, Department of Glycobiology, SLOVAKIA
| | - Monika Poláková
- Institute of Chemistry Slovak Academy of Sciences: Chemicky ustav Slovenskej akademie vied, Department of Glycobiology, SLOVAKIA
| | - Vladimír Puchart
- Institute of Chemistry Slovak Academy of Sciences: Chemicky ustav Slovenskej akademie vied, Department of Carbohydrate Enzymology, Dúbravská cesta 9, 845 38, Bratislava, SLOVAKIA
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4
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Zerva A, Pentari C, Ferousi C, Nikolaivits E, Karnaouri A, Topakas E. Recent advances on key enzymatic activities for the utilisation of lignocellulosic biomass. Bioresour Technol 2021; 342:126058. [PMID: 34597805 DOI: 10.1016/j.biortech.2021.126058] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 09/24/2021] [Accepted: 09/27/2021] [Indexed: 06/13/2023]
Abstract
The field of enzymatic degradation of lignocellulose is actively growing and the recent updates of the last few years indicate that there is still much to learn. The growing number of protein sequences with unknown function in microbial genomes indicates that there is still much to learn on the mechanisms of lignocellulose degradation. In this review, a summary of the progress in the field is presented, including recent discoveries on the nature of the structural polysaccharides, new technologies for the discovery and functional annotation of gene sequences including omics technologies, and the novel lignocellulose-acting enzymes described. Novel enzymatic activities and enzyme families as well as accessory enzymes and their synergistic relationships regarding biomass breakdown are described. Moreover, it is shown that all the valuable knowledge of the enzymatic decomposition of plant biomass polymers can be employed towards the decomposition and upgrading of synthetic polymers, such as plastics.
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Affiliation(s)
- Anastasia Zerva
- Industrial Biotechnology & Biocatalysis Group, Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens, Athens, Greece
| | - Christina Pentari
- Industrial Biotechnology & Biocatalysis Group, Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens, Athens, Greece
| | - Christina Ferousi
- Industrial Biotechnology & Biocatalysis Group, Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens, Athens, Greece
| | - Efstratios Nikolaivits
- Industrial Biotechnology & Biocatalysis Group, Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens, Athens, Greece
| | - Anthi Karnaouri
- Industrial Biotechnology & Biocatalysis Group, Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens, Athens, Greece
| | - Evangelos Topakas
- Industrial Biotechnology & Biocatalysis Group, Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens, Athens, Greece; Biochemical Process Engineering, Chemical Engineering, Department of Civil, Environmental and Natural Resources Engineering, Luleå University of Technology, Luleå, Sweden.
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5
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Leadbeater DR, Oates NC, Bennett JP, Li Y, Dowle AA, Taylor JD, Alponti JS, Setchfield AT, Alessi AM, Helgason T, McQueen-Mason SJ, Bruce NC. Mechanistic strategies of microbial communities regulating lignocellulose deconstruction in a UK salt marsh. Microbiome 2021; 9:48. [PMID: 33597033 PMCID: PMC7890819 DOI: 10.1186/s40168-020-00964-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/03/2020] [Accepted: 12/06/2020] [Indexed: 05/29/2023]
Abstract
BACKGROUND Salt marshes are major natural repositories of sequestered organic carbon with high burial rates of organic matter, produced by highly productive native flora. Accumulated carbon predominantly exists as lignocellulose which is metabolised by communities of functionally diverse microbes. However, the organisms that orchestrate this process and the enzymatic mechanisms employed that regulate the accumulation, composition and permanence of this carbon stock are not yet known. We applied meta-exo-proteome proteomics and 16S rRNA gene profiling to study lignocellulose decomposition in situ within the surface level sediments of a natural established UK salt marsh. RESULTS Our studies revealed a community dominated by Gammaproteobacteria, Bacteroidetes and Deltaproteobacteria that drive lignocellulose degradation in the salt marsh. We identify 42 families of lignocellulolytic bacteria of which the most active secretors of carbohydrate-active enzymes were observed to be Prolixibacteracea, Flavobacteriaceae, Cellvibrionaceae, Saccharospirillaceae, Alteromonadaceae, Vibrionaceae and Cytophagaceae. These families secreted lignocellulose-active glycoside hydrolase (GH) family enzymes GH3, GH5, GH6, GH9, GH10, GH11, GH13 and GH43 that were associated with degrading Spartina biomass. While fungi were present, we did not detect a lignocellulolytic contribution from fungi which are major contributors to terrestrial lignocellulose deconstruction. Oxidative enzymes such as laccases, peroxidases and lytic polysaccharide monooxygenases that are important for lignocellulose degradation in the terrestrial environment were present but not abundant, while a notable abundance of putative esterases (such as carbohydrate esterase family 1) associated with decoupling lignin from polysaccharides in lignocellulose was observed. CONCLUSIONS Here, we identify a diverse cohort of previously undefined bacteria that drive lignocellulose degradation in the surface sediments of the salt marsh environment and describe the enzymatic mechanisms they employ to facilitate this process. Our results increase the understanding of the microbial and molecular mechanisms that underpin carbon sequestration from lignocellulose within salt marsh surface sediments in situ and provide insights into the potential enzymatic mechanisms regulating the enrichment of polyphenolics in salt marsh sediments. Video Abstract.
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Affiliation(s)
- Daniel R Leadbeater
- Centre for Novel Agricultural Products, Department of Biology, University of York, York, YO10 5DD, UK.
| | - Nicola C Oates
- Centre for Novel Agricultural Products, Department of Biology, University of York, York, YO10 5DD, UK
| | - Joseph P Bennett
- Centre for Novel Agricultural Products, Department of Biology, University of York, York, YO10 5DD, UK
| | - Yi Li
- Centre for Novel Agricultural Products, Department of Biology, University of York, York, YO10 5DD, UK
| | - Adam A Dowle
- Bioscience Technology Facility, Department of Biology, University of York, York, YO10 5DD, UK
| | - Joe D Taylor
- School of Chemistry and Biosciences, University of Bradford, Bradford, West Yorkshire, BD7 1DP, UK
| | - Juliana Sanchez Alponti
- Centre for Novel Agricultural Products, Department of Biology, University of York, York, YO10 5DD, UK
| | - Alexander T Setchfield
- Centre for Novel Agricultural Products, Department of Biology, University of York, York, YO10 5DD, UK
| | - Anna M Alessi
- Centre for Novel Agricultural Products, Department of Biology, University of York, York, YO10 5DD, UK
| | | | - Simon J McQueen-Mason
- Centre for Novel Agricultural Products, Department of Biology, University of York, York, YO10 5DD, UK.
| | - Neil C Bruce
- Centre for Novel Agricultural Products, Department of Biology, University of York, York, YO10 5DD, UK.
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Oliveira DM, Mota TR, Salatta FV, de Almeida GHG, Olher VGA, Oliveira MAS, Marchiosi R, Ferrarese-Filho O, Dos Santos WD. Feruloyl esterase activity and its role in regulating the feruloylation of maize cell walls. Plant Physiol Biochem 2020; 156:49-54. [PMID: 32906021 DOI: 10.1016/j.plaphy.2020.08.046] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 08/30/2020] [Indexed: 06/11/2023]
Abstract
Cell walls of grasses have ferulic acid (FA) ester-linked to the arabinosyl substitutions of arabinoxylan (AX). Feruloyl esterases (FAE) are carboxylic acid esterases that release FA from cell walls and synthetic substrates. Despite the importance of FA for cell wall recalcitrance and in response to biotic and abiotic stresses, the physiological function of plant FAEs remains unclear. Here, we developed a simple method for the determination of FAE activity (ZmFAE) in maize using the total protein extract and investigated its role in regulating the feruloylation of cell wall. The method includes a single protein extraction and enzymatic reaction with protein concentration as low as 65 μg at 35 °C for 30 min, using methyl ferulate as the substrate. The methodology allowed the determination of the apparent Km (392.82 μM) and Vmax (79.15 pkat mg-1 protein). We also found that ZmFAE activity was correlated (r = 0.829) with the levels of FA in seedling roots, plant roots and leaves of maize. Furthermore, the exposure to osmotic stress resulted in a 50% increase in ZmFAE activity in seedling roots. These data suggest that FAE-catalyzed reaction is important for cell wall feruloylation during plant development and in response to abiotic stress. We conclude proposing a model for the feruloylation and deferuloylation of AX, which explains the role of FAE in regulating the levels of ester-linked FA. Our model might orient further studies investigating the role of plant FAEs and assist strategies for genetic engineering of grasses to obtain plants with reduced biomass recalcitrance.
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Affiliation(s)
- Dyoni M Oliveira
- Department of Biochemistry, State University of Maringá, Maringá, PR, Brazil.
| | - Thatiane R Mota
- Department of Biochemistry, State University of Maringá, Maringá, PR, Brazil
| | - Fábio V Salatta
- Department of Biochemistry, State University of Maringá, Maringá, PR, Brazil
| | | | | | - Marco A S Oliveira
- Department of Biochemistry, State University of Maringá, Maringá, PR, Brazil
| | - Rogério Marchiosi
- Department of Biochemistry, State University of Maringá, Maringá, PR, Brazil
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7
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Yao Q, Huang M, Bu Z, Zeng J, Wang X, Liu Z, Ma J, Zhang K, Liu X, Zhu Y. Identification and characterization of a novel bacterial carbohydrate esterase from the bacterium Pantoea ananatis Sd-1 with potential for degradation of lignocellulose and pesticides. Biotechnol Lett 2020; 42:1479-88. [PMID: 32144558 DOI: 10.1007/s10529-020-02855-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2019] [Accepted: 02/27/2020] [Indexed: 11/25/2022]
Abstract
OBJECTIVE Identification and characterization of a novel bacterial carbohydrate esterase (PaCes7) with application potential for lignocellulose and pesticide degradation. RESULTS PaCes7 was identified from the lignocellulolytic bacterium, Pantoea ananatis Sd-1 as a new carbohydrate esterase. Recombinant PaCes7 heterologously expressed in Escherichia coli showed a clear preference for esters with short-chain fatty acids and exhibited maximum activity towards α-naphthol acetate at 37 °C and pH 7.5. Purified PaCes7 exhibited its catalytic activity under mesophilic conditions and retained more than 40% activity below 30 °C. It displayed a relatively wide pH stability from pH 6-11. Furthermore, the enzyme was strongly resistant to Mg2+, Pb2+, and Co2+ and activated by K+ and Ca2+. Both P. ananatis Sd-1 and PaCes7 could degrade the pesticide carbaryl. Additionally, PaCes7 was shown to work in combination with cellulase and/or xylanase in rice straw degradation. CONCLUSIONS The data suggest that PaCes7 possesses promising biotechnological potential.
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Kmezik C, Bonzom C, Olsson L, Mazurkewich S, Larsbrink J. Multimodular fused acetyl-feruloyl esterases from soil and gut Bacteroidetes improve xylanase depolymerization of recalcitrant biomass. Biotechnol Biofuels 2020; 13:60. [PMID: 32266006 PMCID: PMC7110780 DOI: 10.1186/s13068-020-01698-9] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Accepted: 03/16/2020] [Indexed: 05/04/2023]
Abstract
BACKGROUND Plant biomass is an abundant and renewable carbon source that is recalcitrant towards both chemical and biochemical degradation. Xylan is the second most abundant polysaccharide in biomass after cellulose, and it possesses a variety of carbohydrate substitutions and non-carbohydrate decorations which can impede enzymatic degradation by glycoside hydrolases. Carbohydrate esterases are able to cleave the ester-linked decorations and thereby improve the accessibility of the xylan backbone to glycoside hydrolases, thus improving the degradation process. Enzymes comprising multiple catalytic glycoside hydrolase domains on the same polypeptide have previously been shown to exhibit intramolecular synergism during degradation of biomass. Similarly, natively fused carbohydrate esterase domains are encoded by certain bacteria, but whether these enzymes can result in similar synergistic boosts in biomass degradation has not previously been evaluated. RESULTS Two carbohydrate esterases with similar architectures, each comprising two distinct physically linked catalytic domains from families 1 (CE1) and 6 (CE6), were selected from xylan-targeting polysaccharide utilization loci (PULs) encoded by the Bacteroidetes species Bacteroides ovatus and Flavobacterium johnsoniae. The full-length enzymes as well as the individual catalytic domains showed activity on a range of synthetic model substrates, corn cob biomass, and Japanese beechwood biomass, with predominant acetyl esterase activity for the N-terminal CE6 domains and feruloyl esterase activity for the C-terminal CE1 domains. Moreover, several of the enzyme constructs were able to substantially boost the performance of a commercially available xylanase on corn cob biomass (close to twofold) and Japanese beechwood biomass (up to 20-fold). Interestingly, a significant improvement in xylanase biomass degradation was observed following addition of the full-length multidomain enzyme from B. ovatus versus the addition of its two separated single domains, indicating an intramolecular synergy between the esterase domains. Despite high sequence similarities between the esterase domains from B. ovatus and F. johnsoniae, their addition to the xylanolytic reaction led to different degradation patterns. CONCLUSION We demonstrated that multidomain carbohydrate esterases, targeting the non-carbohydrate decorations on different xylan polysaccharides, can considerably facilitate glycoside hydrolase-mediated hydrolysis of xylan and xylan-rich biomass. Moreover, we demonstrated for the first time a synergistic effect between the two fused catalytic domains of a multidomain carbohydrate esterase.
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Affiliation(s)
- Cathleen Kmezik
- Division of Industrial Biotechnology, Department of Biology and Biological Engineering, Chalmers University of Technology, 412 96 Gothenburg, Sweden
| | - Cyrielle Bonzom
- Division of Industrial Biotechnology, Department of Biology and Biological Engineering, Chalmers University of Technology, 412 96 Gothenburg, Sweden
| | - Lisbeth Olsson
- Division of Industrial Biotechnology, Department of Biology and Biological Engineering, Chalmers University of Technology, 412 96 Gothenburg, Sweden
- Wallenberg Wood Science Center, Chalmers University of Technology, 412 96 Gothenburg, Sweden
| | - Scott Mazurkewich
- Division of Industrial Biotechnology, Department of Biology and Biological Engineering, Chalmers University of Technology, 412 96 Gothenburg, Sweden
- Wallenberg Wood Science Center, Chalmers University of Technology, 412 96 Gothenburg, Sweden
| | - Johan Larsbrink
- Division of Industrial Biotechnology, Department of Biology and Biological Engineering, Chalmers University of Technology, 412 96 Gothenburg, Sweden
- Wallenberg Wood Science Center, Chalmers University of Technology, 412 96 Gothenburg, Sweden
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Arnling Bååth J, Mazurkewich S, Knudsen RM, Poulsen JCN, Olsson L, Lo Leggio L, Larsbrink J. Biochemical and structural features of diverse bacterial glucuronoyl esterases facilitating recalcitrant biomass conversion. Biotechnol Biofuels 2018; 11:213. [PMID: 30083226 PMCID: PMC6069808 DOI: 10.1186/s13068-018-1213-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Accepted: 07/23/2018] [Indexed: 05/02/2023]
Abstract
BACKGROUND Lignocellulose is highly recalcitrant to enzymatic deconstruction, where the recalcitrance primarily results from chemical linkages between lignin and carbohydrates. Glucuronoyl esterases (GEs) from carbohydrate esterase family 15 (CE15) have been suggested to play key roles in reducing lignocellulose recalcitrance by cleaving covalent ester bonds found between lignin and glucuronoxylan. However, only a limited number of GEs have been biochemically characterized and structurally determined to date, limiting our understanding of these enzymes and their potential exploration. RESULTS Ten CE15 enzymes from three bacterial species, sharing as little as 20% sequence identity, were characterized on a range of model substrates; two protein structures were solved, and insights into their regulation and biological roles were gained through gene expression analysis and enzymatic assays on complex biomass. Several enzymes with higher catalytic efficiencies on a wider range of model substrates than previously characterized fungal GEs were identified. Similarities and differences regarding substrate specificity between the investigated GEs were observed and putatively linked to their positioning in the CE15 phylogenetic tree. The bacterial GEs were able to utilize substrates lacking 4-OH methyl substitutions, known to be important for fungal enzymes. In addition, certain bacterial GEs were able to efficiently cleave esters of galacturonate, a functionality not previously described within the family. The two solved structures revealed similar overall folds to known structures, but also indicated active site regions allowing for more promiscuous substrate specificities. The gene expression analysis demonstrated that bacterial GE-encoding genes were differentially expressed as response to different carbon sources. Further, improved enzymatic saccharification of milled corn cob by a commercial lignocellulolytic enzyme cocktail when supplemented with GEs showcased their synergistic potential with other enzyme types on native biomass. CONCLUSIONS Bacterial GEs exhibit much larger diversity than fungal counterparts. In this study, we significantly expanded the existing knowledge on CE15 with the in-depth characterization of ten bacterial GEs broadly spanning the phylogenetic tree, and also presented two novel enzyme structures. Variations in transcriptional responses of CE15-encoding genes under different growth conditions suggest nonredundant functions for enzymes found in species with multiple CE15 genes and further illuminate the importance of GEs in native lignin-carbohydrate disassembly.
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Affiliation(s)
- Jenny Arnling Bååth
- Wallenberg Wood Science Center, Division of Industrial Biotechnology, Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Scott Mazurkewich
- Wallenberg Wood Science Center, Division of Industrial Biotechnology, Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | | | | | - Lisbeth Olsson
- Wallenberg Wood Science Center, Division of Industrial Biotechnology, Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden
| | - Leila Lo Leggio
- Department of Chemistry, University of Copenhagen, Copenhagen, Denmark
| | - Johan Larsbrink
- Wallenberg Wood Science Center, Division of Industrial Biotechnology, Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg, Sweden
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Hüttner S, Klaubauf S, de Vries RP, Olsson L. Characterisation of three fungal glucuronoyl esterases on glucuronic acid ester model compounds. Appl Microbiol Biotechnol 2017; 101:5301-5311. [PMID: 28429057 PMCID: PMC5486812 DOI: 10.1007/s00253-017-8266-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Revised: 03/12/2017] [Accepted: 03/27/2017] [Indexed: 01/07/2023]
Abstract
The glucuronoyl esterases (GEs) that have been identified so far belong to family 15 of the carbohydrate esterases in the CAZy classification system and are presumed to target ester bonds between lignin alcohols and (4-O-methyl-)d-glucuronic acid residues of xylan. Few GEs have been cloned, expressed and characterised to date. Characterisation has been done on a variety of synthetic substrates; however, the number of commercially available substrates is very limited. We identified novel putative GEs from a wide taxonomic range of fungi and expressed the enzymes originating from Acremonium alcalophilum and Wolfiporia cocos as well as the previously described PcGE1 from Phanerochaete chrysosporium. All three fungal GEs were active on the commercially available compounds benzyl glucuronic acid (BnGlcA), allyl glucuronic acid (allylGlcA) and to a lower degree on methyl glucuronic acid (MeGlcA). The enzymes showed pH stability over a wide pH range and tolerated 6-h incubations of up to 50 °C. Kinetic parameters were determined for BnGlcA. This study shows the suitability of the commercially available model compounds BnGlcA, MeGlcA and allylGlcA in GE activity screening and characterisation experiments. We enriched the spectrum of characterised GEs with two new members of a relatively young enzyme family. Due to its biotechnological significance, this family deserves to be more extensively studied. The presented enzymes are promising candidates as auxiliary enzymes to improve saccharification of plant biomass.
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Affiliation(s)
- Silvia Hüttner
- Division of Industrial Biotechnology, Department of Biology and Biological Engineering, Chalmers University of Technology, SE-412 96, Gothenburg, Sweden.,Wallenberg Wood Science Center, Chalmers University of Technology, SE-412 96, Gothenburg, Sweden
| | - Sylvia Klaubauf
- Division of Industrial Biotechnology, Department of Biology and Biological Engineering, Chalmers University of Technology, SE-412 96, Gothenburg, Sweden.,Wallenberg Wood Science Center, Chalmers University of Technology, SE-412 96, Gothenburg, Sweden
| | - Ronald P de Vries
- Fungal Physiology, CBS-KNAW Fungal Biodiversity Centre & Fungal Molecular Physiology, Utrecht University, 3584 CT, Utrecht, The Netherlands
| | - Lisbeth Olsson
- Division of Industrial Biotechnology, Department of Biology and Biological Engineering, Chalmers University of Technology, SE-412 96, Gothenburg, Sweden. .,Wallenberg Wood Science Center, Chalmers University of Technology, SE-412 96, Gothenburg, Sweden.
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Wilkens C, Busk PK, Pilgaard B, Zhang WJ, Nielsen KL, Nielsen PH, Lange L. Diversity of microbial carbohydrate-active enzymes in Danish anaerobic digesters fed with wastewater treatment sludge. Biotechnol Biofuels 2017; 10:158. [PMID: 28649277 PMCID: PMC5480151 DOI: 10.1186/s13068-017-0840-y] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
BACKGROUND Improved carbohydrate-active enzymes (CAZymes) are needed to fulfill the goal of producing food, feed, fuel, chemicals, and materials from biomass. Little is known about how the diverse microbial communities in anaerobic digesters (ADs) metabolize carbohydrates or which CAZymes that are present, making the ADs a unique niche to look for CAZymes that can potentiate the enzyme blends currently used in industry. RESULTS Enzymatic assays showed that functional CAZymes were secreted into the AD environments in four full-scale mesophilic Danish ADs fed with primary and surplus sludge from municipal wastewater treatment plants. Metagenomes from the ADs were mined for CAZymes with Homology to Peptide Patterns (HotPep). 19,335 CAZymes were identified of which 30% showed 50% or lower identity to known proteins demonstrating that ADs make up a promising pool for discovery of novel CAZymes. A function was assigned to 54% of all CAZymes identified by HotPep. Many different α-glucan-acting CAZymes were identified in the four metagenomes, and the most abundant family was glycoside hydrolase family 13, which contains α-glucan-acting CAZymes. Cellulytic and xylanolytic CAZymes were also abundant in the four metagenomes. The cellulytic enzymes were limited almost to endoglucanases and β-glucosidases, which reflect the large amount of partly degraded cellulose in the sludge. No dockerin domains were identified suggesting that the cellulytic enzymes in the ADs studied operate independently. Of xylanolytic CAZymes, especially xylanases and β-xylosidase, but also a battery of accessory enzymes, were present in the four ADs. CONCLUSIONS Our findings suggest that the ADs are a good place to look for novel plant biomass degrading and modifying enzymes that can potentiate biological processes and provide basis for production of a range of added-value products from biorefineries.
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Affiliation(s)
- Casper Wilkens
- Center for Bioprocess Engineering, Department of Chemical and Biochemical Engineering, Technical University of Denmark, Søltofts Plads, Building 229, 2800 Kongens Lyngby, Denmark
| | - Peter Kamp Busk
- Center for Bioprocess Engineering, Department of Chemical and Biochemical Engineering, Technical University of Denmark, Søltofts Plads, Building 229, 2800 Kongens Lyngby, Denmark
| | - Bo Pilgaard
- Center for Bioprocess Engineering, Department of Chemical and Biochemical Engineering, Technical University of Denmark, Søltofts Plads, Building 229, 2800 Kongens Lyngby, Denmark
| | - Wen-Jing Zhang
- Section for Sustainable Biotechnology, Department of Chemistry and Bioscience, Aalborg University, A. C. Meyers Vænge 15, 2450 Copenhagen, Denmark
- Department of Animal Sciences, University of Wisconsin-Madison, Madison, WI 53706 USA
| | - Kåre L. Nielsen
- Center for Microbial Communities, Section for Biotechnology, Department of Chemistry and Bioscience, Aalborg University, Frederiks Bajer Vej 7, 9220 Aalborg, Denmark
| | - Per Halkjær Nielsen
- Center for Microbial Communities, Section for Biotechnology, Department of Chemistry and Bioscience, Aalborg University, Frederiks Bajer Vej 7, 9220 Aalborg, Denmark
| | - Lene Lange
- Center for Bioprocess Engineering, Department of Chemical and Biochemical Engineering, Technical University of Denmark, Søltofts Plads, Building 229, 2800 Kongens Lyngby, Denmark
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