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Madsen MS, Martins PA, Agger JW. Efficient activity screening of new glucuronoyl esterases using a pNP-based assay. Enzyme Microb Technol 2024; 178:110444. [PMID: 38581869 DOI: 10.1016/j.enzmictec.2024.110444] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Revised: 03/22/2024] [Accepted: 04/02/2024] [Indexed: 04/08/2024]
Abstract
Glucuronoyl esterases (CE15, EC 3.1.1.117) catalyze the hydrolysis of ester bonds between lignin and carbohydrates in lignocellulose. They are widespread within fungi and bacteria, and are subjects to research interest due to their potential applicability in lignocellulose processing. Identifying new and relevant glucuronoyl esterase candidates is challenging because available model substrates poorly represent the natural substrate, which leads to inefficient screening for the activity. In this study, we demonstrate how fifteen novel, fungal, putative glucuronoyl esterases from family CE15 were expressed and screened for activity towards a commercially available, colorimetric assay based on the methyl-ester of 4-O-methyl-aldotriuronic acid linked to para-nitrophenol (methyl ester-UX-β-pNP) and coupled with the activity of GH67 (α-glucuronidase) and GH43 (β-xylosidase) activity. The assay provides easy means for accurately establishing activity and determining specific activity of glucuronoyl esterases. Out of the fifteen expressed CE15 proteins, seven are active and were purified to determine their specific activity. The seven active enzymes originate from Auricularia subglabra (3 proteins), Ganoderma sinensis (2 proteins) and Neocallimastix californiae (2 proteins). Among the CE15 proteins not active towards the screening substrate (methyl ester-UX-β-pNP) were proteins originating from Schizophyllum commune, Podospora anserina, Trametes versicolor, and Coprinopsis cinerea. It is unexpected that CE15 proteins from such canonical lignocellulose degraders do not have the anticipated activity, and these observations call for deeper investigations.
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Affiliation(s)
- Michael S Madsen
- Technical University of Denmark, Lignin Biotechnology, Department of Biotechnology and Biomedicine, Søltofts Plads 224, Kgs Lyngby DK-2800, Denmark
| | - Pedro A Martins
- Technical University of Denmark, Lignin Biotechnology, Department of Biotechnology and Biomedicine, Søltofts Plads 224, Kgs Lyngby DK-2800, Denmark
| | - Jane W Agger
- Technical University of Denmark, Lignin Biotechnology, Department of Biotechnology and Biomedicine, Søltofts Plads 224, Kgs Lyngby DK-2800, Denmark.
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2
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Agger JW, Madsen MS, Martinsen LK, Martins PA, Barrett K, Meyer AS. New insights to diversity and enzyme-substrate interactions of fungal glucuronoyl esterases. Appl Microbiol Biotechnol 2023:10.1007/s00253-023-12575-4. [PMID: 37256329 DOI: 10.1007/s00253-023-12575-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Revised: 05/05/2023] [Accepted: 05/09/2023] [Indexed: 06/01/2023]
Abstract
Glucuronoyl esterases (GEs) (EC 3.1.1.117) catalyze the cleavage of ester-linked lignin-carbohydrate complexes that has high impact on the plant cell wall integrity. The GEs are among the very few known types of hydrolytic enzymes that act at the interface of lignin, or which may potentially interact with lignin itself. In this review, we provide the latest update of the current knowledge on GEs with a special focus on the fungal variants. In addition, we have established the phylogenetic relationship between all GEs and this reveals that the fungal enzymes largely fall into one major branch, together with only a minor subset of bacterial enzymes. About 22% of the fungal proteins carry an additional domain, which is almost exclusively a CBM1 binding domain. We address how GEs may interact with the lignin-side of their substrate by molecular docking experiments based on the known structure of the Cerrena unicolor GE (CuGE). The docking studies indicate that there are no direct interactions between the enzyme and the lignin polymer, that the lignin-moiety is facing away from the protein surface and that an elongated carbon-chain between the ester-linkage and the first phenyl of lignin is preferable. Much basic research on these enzymes has been done over the past 15 years, but the next big step forward for these enzymes is connected to application and how these enzymes can facilitate the use of lignocellulose as a renewable resource. KEY POINTS: Fungal GEs are closely related and are sometimes linked to a binding module Molecular docking suggests good accommodation of lignin-like substructures GEs could be among the first expressed enzymes during fungal growth on biomass.
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Affiliation(s)
- Jane Wittrup Agger
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads 224, 2800, Kongens Lyngby, Denmark.
| | - Michael Schmidt Madsen
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads 224, 2800, Kongens Lyngby, Denmark
| | - Line Korte Martinsen
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads 224, 2800, Kongens Lyngby, Denmark
| | - Pedro Alves Martins
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads 224, 2800, Kongens Lyngby, Denmark
| | - Kristian Barrett
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads 224, 2800, Kongens Lyngby, Denmark
| | - Anne S Meyer
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads 224, 2800, Kongens Lyngby, Denmark
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3
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Glucuronoyl esterases - enzymes to decouple lignin and carbohydrates and enable better utilization of renewable plant biomass. Essays Biochem 2023; 67:493-503. [PMID: 36651189 PMCID: PMC10154605 DOI: 10.1042/ebc20220155] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Revised: 12/09/2022] [Accepted: 01/04/2023] [Indexed: 01/19/2023]
Abstract
Glucuronoyl esterases (GEs) are microbial enzymes able to cleave covalent linkages between lignin and carbohydrates in the plant cell wall. GEs are serine hydrolases found in carbohydrate esterase family 15 (CE15), which belongs to the large α/β hydrolase superfamily. GEs have been shown to reduce plant cell wall recalcitrance by hydrolysing the ester bonds found between glucuronic acid moieties on xylan polysaccharides and lignin. In recent years, the exploration of CE15 has broadened significantly and focused more on bacterial enzymes, which are more diverse in terms of sequence and structure to their fungal counterparts. Similar to fungal GEs, the bacterial enzymes are able to improve overall biomass deconstruction but also appear to have less strict substrate preferences for the uronic acid moiety. The structures of bacterial GEs reveal that they often have large inserts close to the active site, with implications for more extensive substrate interactions than the fungal GEs which have more open active sites. In this review, we highlight the recent work on GEs which has predominantly regarded bacterial enzymes, and discuss similarities and differences between bacterial and fungal enzymes in terms of the biochemical properties, diversity in sequence and modularity, and structural variations that have been discovered thus far in CE15.
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4
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Microbial xylanolytic carbohydrate esterases. Essays Biochem 2022; 67:479-491. [PMID: 36468678 DOI: 10.1042/ebc20220129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Revised: 11/04/2022] [Accepted: 11/17/2022] [Indexed: 12/12/2022]
Abstract
Abstract
This article reviews microbial esterases participating in the degradation of the major plant hemicellulose, xylan. The main chain of this polysaccharide built of β-1,4-glycosidically linked xylopyranosyl residues is substituted by other sugars and also partially acetylated. Besides esters of acetic acid, there are two other types of ester linkages in plant xylans. L-Arabinofuranosyl side chains form esters with phenolic acids, predominantly with ferulic acid. The dimerization of ferulic acid residues leads to cross-links connecting the hemicellulose molecules. Ferulic acid cross-links were shown to serve as covalent linkage between lignin and hemicellulose. Another cross-linking between lignin and hemicellulose is provided by esters between the xylan side residues of glucuronic or 4-O-methyl-D-glucurononic acid and lignin alcohols. Regardless of the cross-linking, the side residues prevent xylan main chains from association that leads to crystallization similar to that of cellulose. Simultaneously, xylan decorations hamper the action of enzymes acting on the main chain. The enzymatic breakdown of plant xylan, therefore, requires a concerted action of glycanases attacking the main chain and enzymes catalyzing debranching, called accessory xylanolytic enzymes including xylanolytic esterases. While acetylxylan esterases and feruloyl esterases participate directly in xylan degradation, glucuronoyl esterases catalyze its separation from lignin. The current state of knowledge of diversity, classification and structure–function relationship of these three types of xylanolytic carbohydrate esterases is discussed with emphasis on important aspects of their future research relevant to their industrial applications.
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Naeem M, Manzoor S, Abid MUH, Tareen MBK, Asad M, Mushtaq S, Ehsan N, Amna D, Xu B, Hazafa A. Fungal Proteases as Emerging Biocatalysts to Meet the Current Challenges and Recent Developments in Biomedical Therapies: An Updated Review. J Fungi (Basel) 2022; 8:jof8020109. [PMID: 35205863 PMCID: PMC8875690 DOI: 10.3390/jof8020109] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Revised: 12/31/2021] [Accepted: 01/05/2022] [Indexed: 02/07/2023] Open
Abstract
With the increasing world population, demand for industrialization has also increased to fulfill humans' living standards. Fungi are considered a source of essential constituents to produce the biocatalytic enzymes, including amylases, proteases, lipases, and cellulases that contain broad-spectrum industrial and emerging applications. The present review discussed the origin, nature, mechanism of action, emerging aspects of genetic engineering for designing novel proteases, genome editing of fungal strains through CRISPR technology, present challenges and future recommendations of fungal proteases. The emerging evidence revealed that fungal proteases show a protective role to many environmental exposures and discovered that an imbalance of protease inhibitors and proteases in the epithelial barriers leads to the protection of chronic eosinophilic airway inflammation. Moreover, mitoproteases recently were found to execute intense proteolytic processes that are crucial for mitochondrial integrity and homeostasis function, including mitochondrial biogenesis, protein synthesis, and apoptosis. The emerging evidence revealed that CRISPR/Cas9 technology had been successfully developed in various filamentous fungi and higher fungi for editing of specific genes. In addition to medical importance, fungal proteases are extensively used in different industries such as foods to prepare butter, fruits, juices, and cheese, and to increase their shelf life. It is concluded that hydrolysis of proteins in industries is one of the most significant applications of fungal enzymes that led to massive usage of proteomics.
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Affiliation(s)
- Muhammad Naeem
- College of Life Science, Hebei Normal University, Shijiazhuang 050025, China;
| | - Saba Manzoor
- Department of Zoology, University of Sialkot, Sialkot 51310, Pakistan;
| | | | | | - Mirza Asad
- Department of Biochemistry, University of Agriculture Faisalabad, Faisalabad 38040, Pakistan;
| | - Sajida Mushtaq
- Department of Zoology, Government College Women University, Sialkot 51040, Pakistan;
| | - Nazia Ehsan
- Department of Zoology, Wildlife and Fisheries, University of Agriculture Faisalabad, Faisalabad 38040, Pakistan;
| | - Dua Amna
- Institute of Food Science & Nutrition, Bahauddin Zakariya University, Multan 60800, Pakistan;
| | - Baojun Xu
- Food Science and Technology Program, Beijing Normal University-Hong Kong Baptist University (BNU-HKBU) United International College, Zhuhai 519087, China
- Correspondence: (B.X.); (A.H.)
| | - Abu Hazafa
- Department of Biochemistry, University of Agriculture Faisalabad, Faisalabad 38040, Pakistan;
- Correspondence: (B.X.); (A.H.)
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6
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Li X, Dilokpimol A, Kabel MA, de Vries RP. Fungal xylanolytic enzymes: Diversity and applications. BIORESOURCE TECHNOLOGY 2022; 344:126290. [PMID: 34748977 DOI: 10.1016/j.biortech.2021.126290] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 10/29/2021] [Accepted: 11/01/2021] [Indexed: 05/26/2023]
Abstract
As important polysaccharide degraders in nature, fungi can diversify their extensive set of carbohydrate-active enzymes to survive in ecological habitats of various composition. Among these enzymes, xylanolytic ones can efficiently and sustainably degrade xylans into (fermentable) monosaccharides to produce valuable chemicals or fuels from, for example relevant for upgrading agro-food industrial side streams. Moreover, xylanolytic enzymes are being used in various industrial applications beyond biomass saccharification, e.g. food, animal feed, biofuel, pulp and paper. As a reference for researchers working in related areas, this review summarized the current knowledge on substrate specificity of xylanolytic enzymes from different families of the Carbohydrate-Active enZyme database. Additionally, the diversity of enzyme sets in fungi were discussed by comparing the number of genes encoding xylanolytic enzymes in selected fungal genomes. Finally, to support bio-economy, the current applications of fungal xylanolytic enzymes in industry were reviewed.
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Affiliation(s)
- Xinxin Li
- Fungal Physiology, Westerdijk Fungal Biodiversity Institute & Fungal Molecular Physiology, Utrecht University, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
| | - Adiphol Dilokpimol
- Fungal Physiology, Westerdijk Fungal Biodiversity Institute & Fungal Molecular Physiology, Utrecht University, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands
| | - Mirjam A Kabel
- Laboratory of Food Chemistry, Wageningen University & Research, Bornse Weilanden 9, 6708 WG Wageningen, The Netherlands
| | - Ronald P de Vries
- Fungal Physiology, Westerdijk Fungal Biodiversity Institute & Fungal Molecular Physiology, Utrecht University, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands.
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7
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Filho JAF, Rosolen RR, Almeida DA, de Azevedo PHC, Motta MLL, Aono AH, dos Santos CA, Horta MAC, de Souza AP. Trends in biological data integration for the selection of enzymes and transcription factors related to cellulose and hemicellulose degradation in fungi. 3 Biotech 2021; 11:475. [PMID: 34777932 PMCID: PMC8548487 DOI: 10.1007/s13205-021-03032-y] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Accepted: 10/15/2021] [Indexed: 12/13/2022] Open
Abstract
Fungi are key players in biotechnological applications. Although several studies focusing on fungal diversity and genetics have been performed, many details of fungal biology remain unknown, including how cellulolytic enzymes are modulated within these organisms to allow changes in main plant cell wall compounds, cellulose and hemicellulose, and subsequent biomass conversion. With the advent and consolidation of DNA/RNA sequencing technology, different types of information can be generated at the genomic, structural and functional levels, including the gene expression profiles and regulatory mechanisms of these organisms, during degradation-induced conditions. This increase in data generation made rapid computational development necessary to deal with the large amounts of data generated. In this context, the origination of bioinformatics, a hybrid science integrating biological data with various techniques for information storage, distribution and analysis, was a fundamental step toward the current state-of-the-art in the postgenomic era. The possibility of integrating biological big data has facilitated exciting discoveries, including identifying novel mechanisms and more efficient enzymes, increasing yields, reducing costs and expanding opportunities in the bioprocess field. In this review, we summarize the current status and trends of the integration of different types of biological data through bioinformatics approaches for biological data analysis and enzyme selection.
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Affiliation(s)
- Jaire A. Ferreira Filho
- Center for Molecular Biology and Genetic Engineering (CBMEG), University of Campinas (UNICAMP), Campinas, SP Brazil
| | - Rafaela R. Rosolen
- Center for Molecular Biology and Genetic Engineering (CBMEG), University of Campinas (UNICAMP), Campinas, SP Brazil
| | - Deborah A. Almeida
- Center for Molecular Biology and Genetic Engineering (CBMEG), University of Campinas (UNICAMP), Campinas, SP Brazil
| | - Paulo Henrique C. de Azevedo
- Center for Molecular Biology and Genetic Engineering (CBMEG), University of Campinas (UNICAMP), Campinas, SP Brazil
| | - Maria Lorenza L. Motta
- Center for Molecular Biology and Genetic Engineering (CBMEG), University of Campinas (UNICAMP), Campinas, SP Brazil
| | - Alexandre H. Aono
- Center for Molecular Biology and Genetic Engineering (CBMEG), University of Campinas (UNICAMP), Campinas, SP Brazil
| | - Clelton A. dos Santos
- Center for Molecular Biology and Genetic Engineering (CBMEG), University of Campinas (UNICAMP), Campinas, SP Brazil
- Brazilian Biorenewables National Laboratory (LNBR), Brazilian Center for Research in Energy and Materials (CNPEM), Campinas, SP Brazil
| | - Maria Augusta C. Horta
- Center for Molecular Biology and Genetic Engineering (CBMEG), University of Campinas (UNICAMP), Campinas, SP Brazil
- Faculty of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP Brazil
| | - Anete P. de Souza
- Center for Molecular Biology and Genetic Engineering (CBMEG), University of Campinas (UNICAMP), Campinas, SP Brazil
- Department of Plant Biology, Institute of Biology, UNICAMP, Universidade Estadual de Campinas, Campinas, SP 13083-875 Brazil
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8
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Tang S, Liao D, Li X, Lin Y, Han S, Zheng S. Cell-Free Biosynthesis System: Methodology and Perspective of in Vitro Efficient Platform for Pyruvate Biosynthesis and Transformation. ACS Synth Biol 2021; 10:2417-2433. [PMID: 34529398 DOI: 10.1021/acssynbio.1c00252] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The modification of intracellular metabolic pathways by metabolic engineering has generated many engineered strains with relatively high yields of various target products in the past few decades. However, the unpredictable accumulation of toxic products, the cell membrane barrier, and competition between the carbon flux of cell growth and product synthesis have severely retarded progress toward the industrial-scale production of many essential chemicals. On the basis of an in-depth understanding of intracellular metabolic pathways, scientists intend to explore more sustainable methods and construct a cell-free biosynthesis system in vitro. In this review, the synthesis and application of pyruvate as a platform compound is used as an example to introduce cell-free biosynthesis systems. We systematically summarize a proposed methodology workflow of cell-free biosynthesis systems, including pathway design, enzyme mining, enzyme modification, multienzyme assembly, and pathway optimization. Some new methods, such as machine learning, are also mentioned in this review.
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Affiliation(s)
- Shiming Tang
- Guangdong Key Laboratory of Fermentation and Enzyme Engineering, School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, PR China
- Guangdong Research Center of Industrial Enzyme and Green Manufacturing Technology, School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, PR China
| | - Daocheng Liao
- Guangdong Key Laboratory of Fermentation and Enzyme Engineering, School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, PR China
- Guangdong Research Center of Industrial Enzyme and Green Manufacturing Technology, School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, PR China
| | - Xuewen Li
- Guangdong Key Laboratory of Fermentation and Enzyme Engineering, School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, PR China
- Guangdong Research Center of Industrial Enzyme and Green Manufacturing Technology, School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, PR China
| | - Ying Lin
- Guangdong Key Laboratory of Fermentation and Enzyme Engineering, School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, PR China
- Guangdong Research Center of Industrial Enzyme and Green Manufacturing Technology, School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, PR China
| | - Shuangyan Han
- Guangdong Key Laboratory of Fermentation and Enzyme Engineering, School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, PR China
- Guangdong Research Center of Industrial Enzyme and Green Manufacturing Technology, School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, PR China
| | - Suiping Zheng
- Guangdong Key Laboratory of Fermentation and Enzyme Engineering, School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, PR China
- Guangdong Research Center of Industrial Enzyme and Green Manufacturing Technology, School of Biology and Biological Engineering, South China University of Technology, Guangzhou 510006, PR China
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9
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Fasim A, More VS, More SS. Large-scale production of enzymes for biotechnology uses. Curr Opin Biotechnol 2020; 69:68-76. [PMID: 33388493 DOI: 10.1016/j.copbio.2020.12.002] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 11/12/2020] [Accepted: 12/08/2020] [Indexed: 01/08/2023]
Abstract
Enzymes are biocatalysts that speed up the chemical reaction to obtain the final valuable product/s. Biotechnology has revolutionized the use of traditional enzymes to be applicable in industries such as food, beverage, personal and household care, agriculture, bioenergy, pharmaceutical, and various other segments. With respect to the exponential growth of enzymes in biotech industries, it becomes important to highlight the advancements and impact of enzyme technology over recent years. In this review article, we discuss the existing and emerging production approaches, applications, developments, and global need for enzymes. Special emphasis is given to the predominantly utilized hydrolytic microbial enzymes in industrial bioprocesses.
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Affiliation(s)
- Aneesa Fasim
- School of Basic and Applied Sciences, Dayananda Sagar University, Bengaluru 560 111, Karnataka, India
| | - Veena S More
- Department of Biotechnology, Sapthagiri College of Engineering, Bengaluru 560 057 Karnataka, India
| | - Sunil S More
- School of Basic and Applied Sciences, Dayananda Sagar University, Bengaluru 560 111, Karnataka, India.
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10
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A De Novo Designed Esterase with p-Nitrophenyl Acetate Hydrolysis Activity. Molecules 2020; 25:molecules25204658. [PMID: 33066055 PMCID: PMC7587395 DOI: 10.3390/molecules25204658] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2020] [Revised: 10/04/2020] [Accepted: 10/10/2020] [Indexed: 11/18/2022] Open
Abstract
Esterases are a large family of enzymes with wide applications in the industry. However, all esterases originated from natural sources, limiting their use in harsh environments or newly- emerged reactions. In this study, we designed a new esterase to develop a new protocol to satisfy the needs for better biocatalysts. The ideal spatial conformation of the serine catalytic triad and the oxygen anion hole at the substrate-binding site was constructed by quantum mechanical calculation. The catalytic triad and oxygen anion holes were then embedded in the protein scaffold using the new enzyme protocol in Rosetta 3. The design results were subsequently evaluated, and optimized designs were used for expression and purification. The designed esterase had significant lytic activities towards p-nitrophenyl acetate, which was confirmed by point mutations. Thus, this study developed a new protocol to obtain novel enzymes that may be useful in unforgiving environments or novel reactions.
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11
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Yajuan Z, Yajuan D, Lingli Z, Zhoukun L, Zhongli C, Yan H. Characterization of a novel aldo-keto reductase with anti-Prelog stereospecificity from Corallococcus sp. EGB. Int J Biol Macromol 2020; 146:36-44. [DOI: 10.1016/j.ijbiomac.2019.12.214] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 12/03/2019] [Accepted: 12/24/2019] [Indexed: 11/26/2022]
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12
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Ernst HA, Mosbech C, Langkilde AE, Westh P, Meyer AS, Agger JW, Larsen S. The structural basis of fungal glucuronoyl esterase activity on natural substrates. Nat Commun 2020; 11:1026. [PMID: 32094331 PMCID: PMC7039992 DOI: 10.1038/s41467-020-14833-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Accepted: 02/06/2020] [Indexed: 01/06/2023] Open
Abstract
Structural and functional studies were conducted of the glucuronoyl esterase (GE) from Cerrena unicolor (CuGE), an enzyme catalyzing cleavage of lignin-carbohydrate ester bonds. CuGE is an α/β-hydrolase belonging to carbohydrate esterase family 15 (CE15). The enzyme is modular, comprised of a catalytic and a carbohydrate-binding domain. SAXS data show CuGE as an elongated rigid molecule where the two domains are connected by a rigid linker. Detailed structural information of the catalytic domain in its apo- and inactivated form and complexes with aldouronic acids reveal well-defined binding of the 4-O-methyl-a-D-glucuronoyl moiety, not influenced by the nature of the attached xylo-oligosaccharide. Structural and sequence comparisons within CE15 enzymes reveal two distinct structural subgroups. CuGE belongs to the group of fungal CE15-B enzymes with an open and flat substrate-binding site. The interactions between CuGE and its natural substrates are explained and rationalized by the structural results, microscale thermophoresis and isothermal calorimetry.
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Affiliation(s)
- Heidi A Ernst
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100, Copenhagen Ø, Denmark
| | - Caroline Mosbech
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads 221, 2800, Kongens Lyngby, Denmark
| | - Annette E Langkilde
- Department of Drug Design and Pharmacology, University of Copenhagen, Universitetsparken 2, 2100, Copenhagen Ø, Denmark
| | - Peter Westh
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads 221, 2800, Kongens Lyngby, Denmark
| | - Anne S Meyer
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads 221, 2800, Kongens Lyngby, Denmark
| | - Jane W Agger
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads 221, 2800, Kongens Lyngby, Denmark.
| | - Sine Larsen
- Department of Chemistry, University of Copenhagen, Universitetsparken 5, 2100, Copenhagen Ø, Denmark.
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13
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de Vries RP, Mäkelä MR. Genomic and Postgenomic Diversity of Fungal Plant Biomass Degradation Approaches. Trends Microbiol 2020; 28:487-499. [PMID: 32396827 DOI: 10.1016/j.tim.2020.01.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 12/15/2019] [Accepted: 01/16/2020] [Indexed: 10/25/2022]
Abstract
Plant biomass degradation by fungi is a widely studied and applied field of science, due to its relevance for the global carbon cycle and many biotechnological applications. Before the genome era, many of the in-depth studies focused on a relatively small number of species, whereas now, many species can be addressed in detail, revealing the large variety in the approach used by fungi to degrade plant biomass. This variation is found at many levels and includes genomic adaptation to the preferred biomass component, but also different approaches to degrade this component by diverse sets of activities encoded in the genome. Even larger differences have been observed using transcriptome and proteome studies, even between closely related species, suggesting a high level of adaptation in individual species. A better understanding of the drivers of this diversity could be highly valuable in developing more efficient biotechnology approaches for the enzymatic conversion of plant biomass.
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Affiliation(s)
- Ronald P de Vries
- Fungal Physiology, Westerdijk Fungal Biodiversity Institute & Fungal Molecular Physiology, Utrecht University, Utrecht, The Netherlands.
| | - Miia R Mäkelä
- Department of Microbiology, University of Helsinki, Helsinki, Finland
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14
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Mäkelä MR, Hildén K, Kowalczyk JE, Hatakka A. Progress and Research Needs of Plant Biomass Degradation by Basidiomycete Fungi. GRAND CHALLENGES IN FUNGAL BIOTECHNOLOGY 2020. [DOI: 10.1007/978-3-030-29541-7_15] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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15
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Krska D, Larsbrink J. Investigation of a thermostable multi-domain xylanase-glucuronoyl esterase enzyme from Caldicellulosiruptor kristjanssonii incorporating multiple carbohydrate-binding modules. BIOTECHNOLOGY FOR BIOFUELS 2020; 13:68. [PMID: 32308737 PMCID: PMC7151638 DOI: 10.1186/s13068-020-01709-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2020] [Accepted: 04/02/2020] [Indexed: 05/05/2023]
Abstract
BACKGROUND Efficient degradation of lignocellulosic biomass has become a major bottleneck in industrial processes which attempt to use biomass as a carbon source for the production of biofuels and materials. To make the most effective use of the source material, both the hemicellulosic as well as cellulosic parts of the biomass should be targeted, and as such both hemicellulases and cellulases are important enzymes in biorefinery processes. Using thermostable versions of these enzymes can also prove beneficial in biomass degradation, as they can be expected to act faster than mesophilic enzymes and the process can also be improved by lower viscosities at higher temperatures, as well as prevent the introduction of microbial contamination. RESULTS This study presents the investigation of the thermostable, dual-function xylanase-glucuronoyl esterase enzyme CkXyn10C-GE15A from the hyperthermophilic bacterium Caldicellulosiruptor kristjanssonii. Biochemical characterization of the enzyme was performed, including assays for establishing the melting points for the different protein domains, activity assays for the two catalytic domains, as well as binding assays for the multiple carbohydrate-binding domains present in CkXyn10C-GE15A. Although the enzyme domains are naturally linked together, when added separately to biomass, the expected boosting of the xylanase action was not seen. This lack of intramolecular synergy might suggest, together with previous data, that increased xylose release is not the main beneficial trait given by glucuronoyl esterases. CONCLUSIONS Due to its thermostability, CkXyn10C-GE15A is a promising candidate for industrial processes, with both catalytic domains exhibiting melting temperatures over 70 °C. Of particular interest is the glucuronoyl esterase domain, as it represents the first studied thermostable enzyme displaying this activity.
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Affiliation(s)
- Daniel Krska
- Division of Industrial Biotechnology, Department of Biology and Biological Engineering, 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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16
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Shin SK, Ko YJ, Hyeon JE, Han SO. Studies of advanced lignin valorization based on various types of lignolytic enzymes and microbes. BIORESOURCE TECHNOLOGY 2019; 289:121728. [PMID: 31277889 DOI: 10.1016/j.biortech.2019.121728] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2019] [Revised: 06/26/2019] [Accepted: 06/28/2019] [Indexed: 06/09/2023]
Abstract
Lignin is a robust material that is considered useless because it has an inhibitory effect on microbes and acts as a physical barrier for cellulose degradation. Therefore, it has been removed from cellulosic biomass to produce high-value materials. However, lignin monomers can be converted to value-added chemicals such as biodegradable plastics and food additives by appropriately engineered microbes. Lignin degradation through peroxidase, laccase and other proteins with auxiliary activity is the first step in lignin valorization. Metabolic engineering of microorganisms for increased tolerance and production yield is the second step for lignin valorization. Here, this review offers a summary of current biotechnologies using various enzymatic activities, synergistic enzyme mixtures and metabolic engineering for lignin valorization in biorefinery.
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Affiliation(s)
- Sang Kyu Shin
- Department of Biotechnology, Korea University, Seoul 02841, Republic of Korea
| | - Young Jin Ko
- Department of Biotechnology, Korea University, Seoul 02841, Republic of Korea
| | - Jeong Eun Hyeon
- Department of Biotechnology, Korea University, Seoul 02841, Republic of Korea; Department of Food Science and Biotechnology, College of Knowledge-Based Services Engineering, Sungshin Women's University, Seoul 01133, Republic of Korea; Department of Food and Nutrition, College of Health & Wellness, Sungshin Women's University, Seoul 01133, Republic of Korea
| | - Sung Ok Han
- Department of Biotechnology, Korea University, Seoul 02841, Republic of Korea.
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17
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Conacher CG, García-Aparicio MP, Coetzee G, van Zyl WH, Gӧrgens JF. Scalable methanol-free production of recombinant glucuronoyl esterase in Pichia pastoris. BMC Res Notes 2019; 12:596. [PMID: 31533815 PMCID: PMC6751620 DOI: 10.1186/s13104-019-4638-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Accepted: 09/11/2019] [Indexed: 11/10/2022] Open
Abstract
OBJECTIVE Glucuronoyl esterase (GE) is an emerging enzyme that improves fractionation of lignin-carbohydrate complexes. However, the commercial availability of GE is limited, which hinders the research of GE-based bioprocesses for its industrial application in lignocellulose biorefineries. This study evaluated a workable, cost-effective, and commercially scalable production strategy to improve the ease of GE-based research. This strategy consisted of a constitutive and methanol-free enzyme production step coupled with a two-step filtration process. The aim was to determine if this strategy can yield copious amounts of GE, by secretion into the extracellular medium with an acceptable purity that could allow its direct application. This approach was further validated for cellobiose dehydrogenase, another emerging lignocellulose degrading enzyme which is scarcely available at high cost. RESULTS The secreted recombinant enzymes were functionally produced in excess of levels previously reported for constitutive production (1489-2780 mg L-1), and were secreted at moderate to high percentages of the total extracellular protein (51-94%). The constant glycerol feed, implemented during fed-batch fermentation, lead to a decline in growth rate and plateaued productivity. Tangential flow ultrafiltration was used to concentrate cell-free enzyme extracts 5-6-fold, reaching enzyme activity levels (1020-202 U L-1) that could allow their direct application.
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Affiliation(s)
- C G Conacher
- Departments of Process Engineering, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa
| | - M P García-Aparicio
- Departments of Process Engineering, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa. .,Departments of Microbiology, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa.
| | - G Coetzee
- Departments of Process Engineering, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa
| | - W H van Zyl
- Departments of Microbiology, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa
| | - J F Gӧrgens
- Departments of Process Engineering, Stellenbosch University, Private Bag X1, Matieland, 7602, South Africa
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18
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Nguyen SN, Flores A, Talamantes D, Dar F, Valdez A, Schwans J, Berlemont R. GeneHunt for rapid domain-specific annotation of glycoside hydrolases. Sci Rep 2019; 9:10137. [PMID: 31300677 PMCID: PMC6626019 DOI: 10.1038/s41598-019-46290-w] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Accepted: 06/26/2019] [Indexed: 12/20/2022] Open
Abstract
The identification of glycoside hydrolases (GHs) for efficient polysaccharide deconstruction is essential for the development of biofuels. Here, we investigate the potential of sequential HMM-profile identification for the rapid and precise identification of the multi-domain architecture of GHs from various datasets. First, as a validation, we successfully reannotated >98% of the biochemically characterized enzymes listed on the CAZy database. Next, we analyzed the 43 million non-redundant sequences from the M5nr data and identified 322,068 unique GHs. Finally, we searched 129 assembled metagenomes retrieved from MG-RAST for environmental GHs and identified 160,790 additional enzymes. Although most identified sequences corresponded to single domain enzymes, many contained several domains, including known accessory domains and some domains never identified in association with GH. Several sequences displayed multiple catalytic domains and few of these potential multi-activity proteins combined potentially synergistic domains. Finally, we produced and confirmed the biochemical activities of a GH5-GH10 cellulase-xylanase and a GH11-CE4 xylanase-esterase. Globally, this "gene to enzyme pipeline" provides a rationale for mining large datasets in order to identify new catalysts combining unique properties for the efficient deconstruction of polysaccharides.
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Affiliation(s)
- S N Nguyen
- Department of Biological Sciences, California State University Long Beach, Long Beach, California, USA
| | - A Flores
- Department of Biological Sciences, California State University Long Beach, Long Beach, California, USA
| | - D Talamantes
- Department of Biological Sciences, California State University Long Beach, Long Beach, California, USA
| | - F Dar
- Department of Biological Sciences, California State University Long Beach, Long Beach, California, USA
| | - A Valdez
- Department of Biological Sciences, California State University Long Beach, Long Beach, California, USA
| | - J Schwans
- Department of Chemistry and Biochemistry, California State University Long Beach, Long Beach, California, USA
| | - R Berlemont
- Department of Biological Sciences, California State University Long Beach, Long Beach, California, USA.
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19
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20
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Karnaouri A, Antonopoulou I, Zerva A, Dimarogona M, Topakas E, Rova U, Christakopoulos P. Thermophilic enzyme systems for efficient conversion of lignocellulose to valuable products: Structural insights and future perspectives for esterases and oxidative catalysts. BIORESOURCE TECHNOLOGY 2019; 279:362-372. [PMID: 30685134 DOI: 10.1016/j.biortech.2019.01.062] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 01/12/2019] [Accepted: 01/15/2019] [Indexed: 06/09/2023]
Abstract
Thermophilic enzyme systems are of major importance nowadays in all industrial processes due to their great performance at elevated temperatures. In the present review, an overview of the current knowledge on the properties of thermophilic and thermotolerant carbohydrate esterases and oxidative enzymes with great thermostability is provided, with respect to their potential use in biotechnological applications. A special focus is given to the lytic polysaccharide monooxygenases that are able to oxidatively cleave lignocellulose through the use of oxygen or hydrogen peroxide as co-substrate and a reducing agent as electron donor. Structural characteristics of the enzymes, including active site conformation and surface properties are discussed and correlated with their substrate specificity and thermostability properties.
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Affiliation(s)
- Anthi Karnaouri
- Biochemical Process Engineering, Chemical Engineering, Department of Civil, Environmental and Natural Resources Engineering, Luleå University of Technology, Luleå, Sweden.
| | - Io Antonopoulou
- Biochemical Process Engineering, Chemical Engineering, Department of Civil, Environmental and Natural Resources Engineering, Luleå University of Technology, Luleå, Sweden
| | - Anastasia Zerva
- Biotechnology Laboratory, Department of Synthesis and Development of Industrial Processes, School of Chemical Engineering, National Technical University of Athens, Athens, Greece
| | - Maria Dimarogona
- Section of Process and Environmental Engineering, Department of Chemical Engineering, University of Patras, 26504 Rio, Patras, Greece
| | - Evangelos Topakas
- Biotechnology Laboratory, Department of Synthesis and Development of Industrial Processes, School of Chemical Engineering, National Technical University of Athens, Athens, Greece
| | - Ulrika Rova
- Biochemical Process Engineering, Chemical Engineering, Department of Civil, Environmental and Natural Resources Engineering, Luleå University of Technology, Luleå, Sweden
| | - Paul Christakopoulos
- Biochemical Process Engineering, Chemical Engineering, Department of Civil, Environmental and Natural Resources Engineering, Luleå University of Technology, Luleå, Sweden.
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21
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Barrett K, Lange L. Peptide-based functional annotation of carbohydrate-active enzymes by conserved unique peptide patterns (CUPP). BIOTECHNOLOGY FOR BIOFUELS 2019; 12:102. [PMID: 31168320 PMCID: PMC6489277 DOI: 10.1186/s13068-019-1436-5] [Citation(s) in RCA: 36] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/27/2018] [Accepted: 04/13/2019] [Indexed: 05/24/2023]
Abstract
BACKGROUND Insight into the function of carbohydrate-active enzymes is required to understand their biological role and industrial potential. There is a need for better use of the ample genomic data in order to enable selection of the most interesting proteins for further studies. The basis for elaborating a new approach to sequence analysis is the hypothesis that when using conserved peptide patterns to determine the similarities between proteins, the exact spacing between conserved adjacent amino acids in the proteins plays a prominent functional role. Thus, the objective of developing the method of conserved unique peptide patterns (CUPP) is to construct a peptide-based grouping and validate the method to provide evidence that CUPP captures function-related features of the individual carbohydrate-active enzymes (as defined by CAZy families). This approach facilitates grouping of enzymes at a level lower than protein families and/or subfamilies. A standardized, efficient, and robust approach to functional annotation of carbohydrate-active enzymes would support improved molecular insight into enzyme-substrate interaction. RESULTS A new nonalignment-based clustering and functional annotation tool was developed that uses conserved unique peptides patterns to perform automated clustering of proteins and formation of protein groups. A peptide-based model was constructed for each of these protein CUPP groups to be used to automatically annotate protein family, subfamily, and EC function of carbohydrate-active enzymes. CUPP prediction can annotate proteins (from any CAZy family) with high F-score to existing family (0.966), subfamily (0.961), and EC-function (0.843). The speed of the CUPP program was estimated and exemplified by prediction of the 504,017 nonredundant proteins of CAZy in less than four CPU hours. CONCLUSION It was possible to construct an automated system for clustering proteins within families and use the resulting CUPP groups to directly build peptide-based models for genome annotation. The CUPP runtime, F-score, sensitivity, and precisions of family and subfamily annotations match or represent an improvement compared to state-of-the-art tools. The speed of the CUPP annotation is similar to the rapid DIAMOND annotation tool. CUPP facilitates automated annotation of full genome assemblies to any CAZy family.
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Affiliation(s)
- Kristian Barrett
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Lene Lange
- BioEconomy, Research & Advisory, Valby, Denmark
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22
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Mosbech C, Holck J, Meyer A, Agger JW. Enzyme kinetics of fungal glucuronoyl esterases on natural lignin-carbohydrate complexes. Appl Microbiol Biotechnol 2019; 103:4065-4075. [PMID: 30949809 DOI: 10.1007/s00253-019-09797-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2019] [Revised: 03/22/2019] [Accepted: 03/23/2019] [Indexed: 12/01/2022]
Abstract
Glucuronoyl esterases (CE15 family) enable targeted cleavage of ester linkages in lignin-carbohydrate complexes (LCCs), particularly those linking lignin and glucuronoyl residues in xylan. A substantial challenge in characterization and kinetic analysis of CE15 enzymes has been the lack of proper substrates. Here, we present an assay using an insoluble LCC-rich lignin fraction from birch; lignin-rich pellet (LRP). The assay employs quantification of enzyme reaction products by LC-MS. The kinetics of four fungal CE15 enzymes, PsGE, CuGE, TtGE, and AfuGE originating from lignocellulose-degrading fungi Punctularia strigosozonata, Cerrena unicolor, Thielavia terrestris, and Armillaria fuscipes respectively were characterized and compared using this new assay. All four enzymes had activity on LRP and showed a clear preference for the insoluble substrate compared with smaller soluble LCC mimicking esters. End-product profiles were near identical for the four enzymes but differences in kinetic parameters were observed. TtGE possesses an alternative active site compared with the three other enzymes as it has the position of the catalytic glutamic acid occupied by a serine. TtGE performed poorly compared with the other enzymes. We speculate that glucuronoyl LCCs are not the preferred substrate of TtGE. Removal of an N-terminal CBM on CuGE affected the catalytic efficiently of the enzyme by reducing Kcat by more than 30%. Reaction products were detected from all four CE15s on a similar substrate from spruce indicating a more generic GE activity not limited to the hardwood. The assay with natural substrate represents a novel tool to study the natural function and kinetics of CE15s.
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Affiliation(s)
- Caroline Mosbech
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads 221, DK-2800, Kongens Lyngby, Denmark
| | - Jesper Holck
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads 221, DK-2800, Kongens Lyngby, Denmark
| | - Anne Meyer
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads 221, DK-2800, Kongens Lyngby, Denmark
| | - Jane Wittrup Agger
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Søltofts Plads 221, DK-2800, Kongens Lyngby, Denmark.
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23
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Tang J, Long L, Cao Y, Ding S. Expression and characterization of two glucuronoyl esterases from Thielavia terrestris and their application in enzymatic hydrolysis of corn bran. Appl Microbiol Biotechnol 2019; 103:3037-3048. [DOI: 10.1007/s00253-019-09662-w] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2018] [Revised: 01/08/2019] [Accepted: 01/22/2019] [Indexed: 01/13/2023]
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Monrad RN, Eklöf J, Krogh KBRM, Biely P. Glucuronoyl esterases: diversity, properties and biotechnological potential. A review. Crit Rev Biotechnol 2018; 38:1121-1136. [PMID: 29739247 DOI: 10.1080/07388551.2018.1468316] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
Abstract
Glucuronoyl esterases (GEs) belonging to the carbohydrate esterase family 15 (CE15) are involved in microbial degradation of lignocellulosic plant materials. GEs are capable of degrading complex polymers of lignin and hemicellulose cleaving ester bonds between glucuronic acid residues in xylan and lignin alcohols. GEs promote separation of lignin, hemicellulose and cellulose which is crucial for efficient utilization of biomass as an energy source and feedstock for further processing into products or chemicals. Genes encoding GEs are found in both fungi and bacteria, but, so far, bacterial GEs are essentially unexplored, and despite being discovered >10 years ago, only a limited number of GEs have been characterized. The first laboratory scale example of improved xylose and glucuronic acid release by the synergistic action of GE with cellulolytic enzymes was only reported recently (improved C5 sugar and glucuronic acid yields) and, until now, not much is known about their biotechnology potential. In this review, we discuss the diversity, structure and properties of microbial GEs and consider the status of their action on natural substrates and in biological systems in relation to their future industrial use.
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Affiliation(s)
| | | | | | - Peter Biely
- b Institute of Chemistry, Slovak Academy of Sciences , Bratislava , Slovak Republic
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25
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Mosbech C, Holck J, Meyer AS, Agger JW. The natural catalytic function of CuGE glucuronoyl esterase in hydrolysis of genuine lignin-carbohydrate complexes from birch. BIOTECHNOLOGY FOR BIOFUELS 2018; 11:71. [PMID: 29560026 PMCID: PMC5858132 DOI: 10.1186/s13068-018-1075-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Accepted: 03/09/2018] [Indexed: 05/08/2023]
Abstract
BACKGROUND Glucuronoyl esterases belong to carbohydrate esterase family 15 and catalyze de-esterification. Their natural function is presumed to be cleavage of ester linkages in lignin-carbohydrate complexes particularly those linking lignin and glucuronoyl residues in xylans in hardwood. RESULTS Here, we show for the first time a detailed product profile of aldouronic acids released from birchwood lignin by a glucuronoyl esterase from the white-rot fungus Cerrena unicolor (CuGE). CuGE releases substrate for GH10 endo-xylanase which results in significantly increased product release compared to the action of endo-xylanase alone. CuGE also releases neutral xylo-oligosaccharides that can be ascribed to the enzymes feruloyl esterase side activity as demonstrated by release of ferulic acid from insoluble wheat arabinoxylan. CONCLUSION The data verify the enzyme's unique ability to catalyze removal of all glucuronoxylan associated with lignin and we propose that this is a direct result of enzymatic cleavage of the ester bonds connecting glucuronoxylan to lignin via 4-O-methyl glucuronoyl-ester linkages. This function appears important for the fungal organism's ability to effectively utilize all available carbohydrates in lignocellulosic substrates. In bioprocess perspectives, this enzyme is a clear candidate for polishing lignin for residual carbohydrates to achieve pure, native lignin fractions after minimal pretreatment.
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Affiliation(s)
- Caroline Mosbech
- Center for Bioprocess Engineering, Department of Chemical and Biochemical Engineering, Technical University of Denmark, Søltofts Plads 229, 2800 Kgs. Lyngby, Denmark
| | - Jesper Holck
- Center for Bioprocess Engineering, Department of Chemical and Biochemical Engineering, Technical University of Denmark, Søltofts Plads 229, 2800 Kgs. Lyngby, Denmark
| | - Anne S. Meyer
- Center for Bioprocess Engineering, Department of Chemical and Biochemical Engineering, Technical University of Denmark, Søltofts Plads 229, 2800 Kgs. Lyngby, Denmark
| | - Jane Wittrup Agger
- Center for Bioprocess Engineering, Department of Chemical and Biochemical Engineering, Technical University of Denmark, Søltofts Plads 229, 2800 Kgs. Lyngby, Denmark
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