1
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Pentari C, Katsimpouras C, Haon M, Berrin JG, Zerva A, Topakas E. Exploring the synergy between fungal CE15 glucuronoyl esterases and xylanases for lignocellulose saccharification. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2025; 18:38. [PMID: 40140928 PMCID: PMC11948903 DOI: 10.1186/s13068-025-02639-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2024] [Accepted: 03/14/2025] [Indexed: 03/28/2025]
Abstract
BACKGROUND Lignin-carbohydrate complexes in lignocellulosic biomass act as a barrier to its biodegradation and biotechnological exploitation. Enzymatic dissociation between lignin and hemicellulose is a key process that allows the efficient bioconversion of both polymers. Glucuronoyl esterases of the Carbohydrate Esterase 15 family target the ester linkages between the glucuronic acid of xylan and lignin moieties, assisting enzymatic biodegradation of lignocellulose. RESULTS In this study, two CE15 glucuronoyl esterases from the white-rot fungi Artolenzites elegans and Trametes ljubarskyi were heterologously expressed in Pichia pastoris and biochemically characterized on the model substrate D-glucuronic acid ester with cinnamyl alcohol and a variety of pretreated lignocellulosic biomasses. The pretreatment method was shown to be a determining factor in revealing both the activity of the esterases on lignocellulose and their synergistic relationships with other hemicellulases. AeGE15 and TlGE15 demonstrated activity on pretreated biomass with high hemicellulose and lignin content, increasing saccharification by 57 ± 1 μM and 61 ± 3 μM of xylose equivalents, respectively. Furthermore, the synergy between these CE15 esterases and three xylanases from distinct glycoside hydrolase families (GH10, GH11 and GH30) was investigated on pretreated lignocellulosic samples, highlighting beneficial enzymatic interplays. Pretreated birchwood degradation by AnXyn11 was increased from 6% to approximately 10% by the esterases, based on xylose equivalents of unsubstituted xylooligomers. The GEs also promoted the glucuronoxylanase specificity of TtXyn30A, leading up to three-times higher release in aldouronic acids. Finally, a synergistic effect between AeGE15 and TmXyn10 was observed on pretreated corn bran, increasing xylose and xylotriose release by 27 ± 8% and 55 ± 15%, respectively. CONCLUSIONS Both CE15 esterases promoted biomass saccharification by the xylanases, while there was a prominent effect on the GH30 glucuronoxylanase regarding the release of aldouronic acids. Overall, this study shed some light on the role of CE15 glucuronoyl esterases in the enzymatic biodegradation of plant biomass, particularly its (arabino)glucuronoxylan component, during cooperative activity with xylanases.
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Affiliation(s)
- Christina Pentari
- Industrial Biotechnology & Biocatalysis Group, School of Chemical Engineering, National Technical University of Athens, 9 Iroon Polytechniou Str., Zografou Campus, 15772, Athens, Greece
| | - Constantinos Katsimpouras
- Department of Chemical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, 02139 MA, USA
| | - Mireille Haon
- INRAE, Aix Marseille Univ., BBF, Biodiversité et Biotechnologie Fongiques, 13009, Marseille, France
| | - Jean-Guy Berrin
- INRAE, Aix Marseille Univ., BBF, Biodiversité et Biotechnologie Fongiques, 13009, Marseille, France
| | - Anastasia Zerva
- Laboratory of Enzyme Technology, Department of Biotechnology, School of Applied Biology and Biotechnology, Agricultural University of Athens, 75 Iera Odos Street, 11855, Athens, Greece
| | - Evangelos Topakas
- Industrial Biotechnology & Biocatalysis Group, School of Chemical Engineering, National Technical University of Athens, 9 Iroon Polytechniou Str., Zografou Campus, 15772, Athens, Greece.
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2
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Koh S, Saito Y, Kudo H, Taguchi S, Kumagai A, Mizuno M, Samejima M, Amano Y. Synthesis of a natural core substrate with lignin-xylan cross-linkage for unveiling the productive kinetic parameters of glucuronoyl esterase. Biochem Biophys Res Commun 2024; 734:150642. [PMID: 39316949 DOI: 10.1016/j.bbrc.2024.150642] [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: 06/07/2024] [Revised: 08/28/2024] [Accepted: 09/01/2024] [Indexed: 09/26/2024]
Abstract
Lignin-carbohydrate complexes (LCCs) present a considerable hurdle to the economic utilization of lignocellulosic biomass. Glucuronoyl esterase (GE) is an LCC-degrading enzyme that catalyzes the cleavage of the cross-linkages between lignin and xylan in LCCs. Benzyl-d-glucuronate (Bn-GlcA), a commercially available substrate, is widely used to evaluate GE activity assays. However, since Bn-GlcA lacks the structural backbone of naturally occurring LCCs, the mechanisms underlying the activity of GEs and their diversity in the structure-activity relationship are not fully understood. Herein, we provided a synthesis scheme for designing 1,23-α-d-(6-benzyl-4-O-methyl-glucuronyl)-1,4-β-d-xylotriose (Bn-MeGlcA3Xyl3) as a natural core substrate bearing cross-linkage between lignin and glucuronoxylan. A well-defined and yet more realistic synthetic substrate was successfully synthesized via a key step of the benzyl esterification of 4-O-methyl-glucuronyl-1,4-β-d-xylotriose (MeGlcA3Xyl3), a minimized fragment of glucuronoxylan enzymatically digested by β-1,4-xylanase. To the best of our knowledge, this is the first report of the productive GE kinetic analysis using this substrate. Kinetic parameters of the GE from the fungal Pestalotiopsis sp. AN-7 (PesGE), i.e., the Km, Vmax, and kcat of Bn-MeGlcA3Xyl3, were 0.43 mM, 55.5 μmol min-1·mg-1, and 35.8 s-1, respectively. On the other hand, as reported to date, the productive kinetic parameters for Bn-GlcA were not obtained because of its excessively high Km value (>16 mM). The substantial variance in the enzymatic activity of PesGE regarding substrate-binding affinity between Bn-MeGlcA3Xyl3 and Bn-GlcA was also demonstrated using in silico docking simulation. These results suggested that the extended xylan fragment is a key structural determinant affecting PesGE's substrate recognition. Furthermore, the presence of a natural xylan backbone allows for evaluating the enzyme activity of xylan-degrading enzymes. Accordingly, the synthesized substrate with the natural core structure of LCC allowed us to unveil the productive kinetic parameters of GEs, serving as a versatile substrate for further elucidating the cascade reaction of GE and xylan-degrading enzymes.
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Affiliation(s)
- Sangho Koh
- Department of Bioscience and Textile Technology, Interdisciplinary Graduate School of Science and Technology, Shinshu University, 4-17-1 Wakasato, Nagano, 380-8553, Japan.
| | - Yasuko Saito
- Research Institute for Sustainable Chemistry, Department of Materials and Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), 3-11-32 Kagamiyama, Higashi-Hiroshima, Hiroshima, 737-0046, Japan
| | - Hisashi Kudo
- Graduate School of Science, Technology and Innovation, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe, Hyogo, 657-8501, Japan
| | - Seiichi Taguchi
- Graduate School of Science, Technology and Innovation, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe, Hyogo, 657-8501, Japan; Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodaicho, Nada-ku, Kobe, Hyogo, 657-8501, Japan
| | - Akio Kumagai
- Research Institute for Sustainable Chemistry, Department of Materials and Chemistry, National Institute of Advanced Industrial Science and Technology (AIST), 3-11-32 Kagamiyama, Higashi-Hiroshima, Hiroshima, 737-0046, Japan
| | - Masahiro Mizuno
- Faculty of Engineering, Shinshu University, 4-17-1 Wakasato, Nagano, 380-8553, Japan
| | - Masahiro Samejima
- Faculty of Engineering, Shinshu University, 4-17-1 Wakasato, Nagano, 380-8553, Japan
| | - Yoshihiko Amano
- Faculty of Engineering, Shinshu University, 4-17-1 Wakasato, Nagano, 380-8553, Japan.
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3
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Zhang P, Long L, Ding S. Insight into lignin-carbohydrate ester change in pretreated corn bran and its enzymatic hydrolysis by three glucuronoyl esterases from Sordaria brevicollis. Int J Biol Macromol 2024; 282:137308. [PMID: 39510460 DOI: 10.1016/j.ijbiomac.2024.137308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2024] [Revised: 10/15/2024] [Accepted: 11/04/2024] [Indexed: 11/15/2024]
Abstract
Lignin-carbohydrate esters (LC-esters) formed by glucuronoarabinoxylan and lignin are a key factor for the recalcitrance of corn bran, understanding LC-esters change during pretreatment and enzymatic hydrolysis by glucuronoyl esterases (GEs) is essential to the sustainable utilization of corn bran. Herein, hydrolysis performances of three GEs, SbGE15A, SbGE15B, and SbGE15C from Sordaria brevicollis with different subclades and modularity, and changes in enzyme-reachable LC-esters during different pretreatments of corn bran have been comprehensively compared. FB enzymes, SbGE15B and SbGE15C showed higher catalytic activity towards model and natural substrates than FA enzyme, SbGE15A. Particularly, SbGE15C harboring carbohydrate-binding module 1 (CBM1) exhibited much superior catalytic performance and synergistic effect with GH10 endo-xylanase EpXYN1 from Eupenicillium parvum on pretreated residues than SbGE15A and SbGE15B without CBM1. Autohydrolysis and DES (ChCl-LA) pretreatment could decrease the content of enzyme-reachable LC-esters and depolymerize its structure, transitioning from Lignin-(Me)GlcA-Xylan to Lignin-(Me)GlcA-XOS, and eventually to Lignin-(Me)GlcA with increasing pretreatment time. These changes consequently cause a decrease in synergy between SbGE15s and EpXYN1 or commercial enzyme cocktails on pretreated residues. The findings provide new insights into significant changes in enzyme-reachable LC-esters depending on the pretreatment method and intensity and the consequent influence of these changes on the catalytic action of GEs.
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Affiliation(s)
- Peiyu Zhang
- The Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Jiangsu Key Lab for the Chemistry & Utilization of Agricultural and Forest Biomass, College of Chemical Engineering, Nanjing Forestry University, Nanjing 210037, Jiangsu, China.
| | - Liangkun Long
- The Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Jiangsu Key Lab for the Chemistry & Utilization of Agricultural and Forest Biomass, College of Chemical Engineering, Nanjing Forestry University, Nanjing 210037, Jiangsu, China.
| | - Shaojun Ding
- The Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Jiangsu Key Lab for the Chemistry & Utilization of Agricultural and Forest Biomass, College of Chemical Engineering, Nanjing Forestry University, Nanjing 210037, Jiangsu, China.
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4
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Gruninger RJ, Kevorkova M, Low KE, Jones DR, Worrall L, McAllister TA, Abbott DW. Structural, Biochemical, and Phylogenetic Analysis of Bacterial and Fungal Carbohydrate Esterase Family 15 Glucuronoyl Esterases in the Rumen. Protein J 2024; 43:910-922. [PMID: 39153129 PMCID: PMC11345330 DOI: 10.1007/s10930-024-10221-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/28/2024] [Indexed: 08/19/2024]
Abstract
Glucuronoyl esterases (GEs) are carbohydrate active enzymes in carbohydrate esterase family 15 which are involved in the hydrolysis of lignin-carbohydrate complexes. They are encoded by a wide range of aerobic and anaerobic fungi and bacteria inhabiting diverse environments. The rumen microbiome is a complex microbial community with a wide array of enzymes that specialize in deconstructing plant cell wall carbohydrates. Enzymes from the rumen tend to show low similarity to homologues found in other environments, making the rumen microbiome a promising source for the discovery of novel enzymes. Using a combination of phylogenetic and structural analysis, we investigated the structure-function relationship of GEs from the rumen bacteria Fibrobacter succinogenes and Ruminococcus flavefaciens, and from the rumen fungus, Piromyces rhizinflata. All adopt a canonical α/β hydrolase fold and possess a structurally conserved Ser-His-Glu/Asp catalytic triad. Structural variations in the enzymes are localized to loops surrounding the active site. Analysis of the active site structures in these enzymes emphasized the importance of structural plasticity in GEs with non-canonical active site conformations. We hypothesize that interkingdom HGT events may have contributed to the diversity of GEs in the rumen, and this is demonstrated by the phylogenetic and structural similarity observed between rumen bacterial and fungal GEs. This study advances our understanding of the structure-function relationship in glucuronoyl esterases and illuminates the evolutionary dynamics that contribute to enzyme diversity in the rumen microbiome.
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Affiliation(s)
- Robert J Gruninger
- Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada, Lethbridge, AB, Canada.
| | - Maya Kevorkova
- Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada, Lethbridge, AB, Canada
| | - Kristin E Low
- Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada, Lethbridge, AB, Canada
| | - Darryl R Jones
- Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada, Lethbridge, AB, Canada
| | - Liam Worrall
- Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
| | - Tim A McAllister
- Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada, Lethbridge, AB, Canada
| | - D Wade Abbott
- Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada, Lethbridge, AB, Canada
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5
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Wang R, Arioka M. Glucuronoyl esterase facilitates biomass degradation in Neurospora crassa by upregulating the expression of plant biomass-degrading enzymes. J GEN APPL MICROBIOL 2023; 68:278-286. [PMID: 35858815 DOI: 10.2323/jgam.2022.06.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Glucuronoyl esterase (GE) is a promising agent for the delignification of plant biomass since it has been shown to cleave the linkage between xylan and lignin in vitro. In this study, we demonstrate that NcGE, a GE from Neurospora crassa, stimulates plant biomass degradation. In vitro, NcGE synergistically increased the release of reducing sugars from plant biomass when added together with cellulase or xylanase. In vivo, overexpression of NcGE in N. crassa resulted in an increase in xylanolytic activity. Consistently, elevated transcription of genes encoding the major plant biomass degrading-enzymes (PBDEs) was observed in the NcGE overexpression strain. Increased xylanolytic activity and transcription of PDBE genes were largely abolished when the transcription factors clr-1, clr-2, or xlr-1 were deleted. Interestingly, the expression of some PBDE genes was increased when the hydrolysate of plant biomass by NcGE was added to the culture medium. We propose that NcGE boosts the production of PBDEs through the activation of key transcription factors, which is presumably caused by NcGE-mediated generation of hypothetical inducer(s) from plant biomass.
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Affiliation(s)
- Ruijie Wang
- Department of Biotechnology, The University of Tokyo
| | - Manabu Arioka
- Department of Biotechnology, The University of Tokyo.,Collaborative Research Institute for Innovative Microbiology (CRIIM), The University of Tokyo
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6
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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: 8] [Impact Index Per Article: 4.0] [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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7
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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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8
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Viegas MF, Neves RPP, Ramos MJ, Fernandes PA. QM/MM Study of the Reaction Mechanism of Thermophilic Glucuronoyl Esterase for Biomass Treatment. Chemphyschem 2022; 23:e202200269. [PMID: 35925549 DOI: 10.1002/cphc.202200269] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 06/23/2022] [Indexed: 11/06/2022]
Abstract
Hydrolysis of lignocellulosic biomass, composed of a lignin-carbohydrate-complex (LCC) matrix, is critical for producing bioethanol from glucose. However, current methods for LCC processing require costly and polluting processes. The fungal Thermothelomyces thermophila glucuronoyl esterase (TtGE) is a promising thermophilic enzyme that hydrolyses LCC ester bonds. This study describes the TtGE catalytic mechanism using QM/MM methods. Two nearly-degenerate rate-determining transition states were found, with barriers of 16 and 17 kcal ⋅ mol-1 , both with a zwitterionic nature that results from a proton interplay from His346 to either the Ser213-hydroxyl or the lignin leaving group and the rehybridisation of the ester moiety of the substrate to an alkoxide. An oxyanion hole, characteristic of esterases, was provided by the conserved Arg214 through its backbone and sidechain. Our work further suggests that a mutation of Glu267 to a non-negative residue will decrease the energetic barrier in ca. -5 kcal ⋅ mol-1 , improving the catalytic rate of TtGE.
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Affiliation(s)
- Matilde F Viegas
- Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre s/n, 4169-007, Porto, Portugal
| | - Rui P P Neves
- Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre s/n, 4169-007, Porto, Portugal
| | - Maria J Ramos
- Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre s/n, 4169-007, Porto, Portugal
| | - Pedro A Fernandes
- Departamento de Química e Bioquímica, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre s/n, 4169-007, Porto, Portugal
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9
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Mechanism and biomass association of glucuronoyl esterase: an α/β hydrolase with potential in biomass conversion. Nat Commun 2022; 13:1449. [PMID: 35304453 PMCID: PMC8933493 DOI: 10.1038/s41467-022-28938-w] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Accepted: 02/11/2022] [Indexed: 12/02/2022] Open
Abstract
Glucuronoyl esterases (GEs) are α/β serine hydrolases and a relatively new addition in the toolbox to reduce the recalcitrance of lignocellulose, the biggest obstacle in cost-effective utilization of this important renewable resource. While biochemical and structural characterization of GEs have progressed greatly recently, there have yet been no mechanistic studies shedding light onto the rate-limiting steps relevant for biomass conversion. The bacterial GE OtCE15A possesses a classical yet distinctive catalytic machinery, with easily identifiable catalytic Ser/His completed by two acidic residues (Glu and Asp) rather than one as in the classical triad, and an Arg side chain participating in the oxyanion hole. By QM/MM calculations, we identified deacylation as the decisive step in catalysis, and quantified the role of Asp, Glu and Arg, showing the latter to be particularly important. The results agree well with experimental and structural data. We further calculated the free-energy barrier of post-catalysis dissociation from a complex natural substrate, suggesting that in industrial settings non-catalytic processes may constitute the rate-limiting step, and pointing to future directions for enzyme engineering in biomass utilization. Zong and coworkers combine computational and experimental methods to decipher in detail the mechanism of action of glucuronoyl esterases, enzymes with significant biotechnological potential for decoupling lignin from polysaccharides in biomass.
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10
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Krska D, Mazurkewich S, Brown HA, Theibich Y, Poulsen JCN, Morris AL, Koropatkin NM, Lo Leggio L, Larsbrink J. Structural and Functional Analysis of a Multimodular Hyperthermostable Xylanase-Glucuronoyl Esterase from Caldicellulosiruptor kristjansonii. Biochemistry 2021; 60:2206-2220. [PMID: 34180241 PMCID: PMC8280721 DOI: 10.1021/acs.biochem.1c00305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
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The hyperthermophilic bacterium Caldicellulosiruptor kristjansonii encodes an unusual enzyme, CkXyn10C-GE15A, which
incorporates two catalytic domains, a xylanase and a glucuronoyl esterase,
and five carbohydrate-binding modules (CBMs) from families 9 and 22.
The xylanase and glucuronoyl esterase catalytic domains were recently
biochemically characterized, as was the ability of the individual
CBMs to bind insoluble polysaccharides. Here, we further probed the
abilities of the different CBMs from CkXyn10C-GE15A
to bind to soluble poly- and oligosaccharides using affinity gel electrophoresis,
isothermal titration calorimetry, and differential scanning fluorimetry.
The results revealed additional binding properties of the proteins
compared to the former studies on insoluble polysaccharides. Collectively,
the results show that all five CBMs have their own distinct binding
preferences and appear to complement each other and the catalytic
domains in targeting complex cell wall polysaccharides. Additionally,
through renewed efforts, we have achieved partial structural characterization
of this complex multidomain protein. We have determined the structures
of the third CBM9 domain (CBM9.3) and the glucuronoyl esterase (GE15A)
by X-ray crystallography. CBM9.3 is the second CBM9 structure determined
to date and was shown to bind oligosaccharide ligands at the same
site but in a different binding mode compared to that of the previously
determined CBM9 structure from Thermotoga maritima. GE15A represents a unique intermediate between reported fungal
and bacterial glucuronoyl esterase structures as it lacks two inserted
loop regions typical of bacterial enzymes and a third loop has an
atypical structure. We also report small-angle X-ray scattering measurements
of the N-terminal CBM22.1–CBM22.2–Xyn10C construct,
indicating a compact arrangement at room temperature.
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Affiliation(s)
- Daniel Krska
- Division of Industrial Biotechnology, Department of Biology and Biological Engineering, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden
| | - Scott Mazurkewich
- 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
| | - Haley A Brown
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Yusuf Theibich
- Department of Chemistry, University of Copenhagen, DK-2100 Copenhagen, Denmark
| | | | - Adeline L Morris
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Nicole M Koropatkin
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan 48109, United States
| | - Leila Lo Leggio
- Department of Chemistry, University of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Johan Larsbrink
- 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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11
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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: 22] [Impact Index Per Article: 4.4] [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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12
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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: 3.2] [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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13
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Mazurkewich S, Poulsen JCN, Lo Leggio L, Larsbrink J. Structural and biochemical studies of the glucuronoyl esterase OtCE15A illuminate its interaction with lignocellulosic components. J Biol Chem 2019; 294:19978-19987. [PMID: 31740581 PMCID: PMC6937553 DOI: 10.1074/jbc.ra119.011435] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 11/11/2019] [Indexed: 12/28/2022] Open
Abstract
Glucuronoyl esterases (GEs) catalyze the cleavage of ester linkages between lignin and glucuronic acid moieties on glucuronoxylan in plant biomass. As such, GEs represent promising biochemical tools in industrial processing of these recalcitrant resources. However, details on how GEs interact and catalyze degradation of their natural substrates are sparse, calling for thorough enzyme structure-function studies. Presented here is a structural and mechanistic investigation of the bacterial GE OtCE15A. GEs belong to the carbohydrate esterase family 15 (CE15), which is in turn part of the larger α/β-hydrolase superfamily. GEs contain a Ser-His-Asp/Glu catalytic triad, but the location of the catalytic acid in GEs has been shown to be variable, and OtCE15A possesses two putative catalytic acidic residues in the active site. Through site-directed mutagenesis, we demonstrate that these residues are functionally redundant, possibly indicating the evolutionary route toward new functionalities within the family. Structures determined with glucuronate, in both native and covalently bound intermediate states, and galacturonate provide insights into the catalytic mechanism of CE15. A structure of OtCE15A with the glucuronoxylooligosaccharide 23-(4-O-methyl-α-d-glucuronyl)-xylotriose (commonly referred to as XUX) shows that the enzyme can indeed interact with polysaccharides from the plant cell wall, and an additional structure with the disaccharide xylobiose revealed a surface binding site that could possibly indicate a recognition mechanism for long glucuronoxylan chains. Collectively, the results indicate that OtCE15A, and likely most of the CE15 family, can utilize esters of glucuronoxylooligosaccharides and support the proposal that these enzymes work on lignin-carbohydrate complexes in plant biomass.
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Affiliation(s)
- Scott Mazurkewich
- Wallenberg Wood Science Center, Division of Industrial Biotechnology, Department of Biology and Biological Engineering, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden
| | | | - Leila Lo Leggio
- Department of Chemistry, University of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Johan Larsbrink
- Wallenberg Wood Science Center, Division of Industrial Biotechnology, Department of Biology and Biological Engineering, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden
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14
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Cao J, Wang M, Chen W, She Y, Wang J, Wang F, Lao S. Artificial Esterase Based on Self-assembly Gel Microspheres Constructed from Chitosan and Amino Acids. Chem Res Chin Univ 2019. [DOI: 10.1007/s40242-019-8283-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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15
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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: 1.8] [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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16
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Arnling Bååth J, Mazurkewich S, Poulsen JCN, Olsson L, Lo Leggio L, Larsbrink J. Structure-function analyses reveal that a glucuronoyl esterase from Teredinibacter turnerae interacts with carbohydrates and aromatic compounds. J Biol Chem 2019; 294:6635-6644. [PMID: 30814248 PMCID: PMC6484129 DOI: 10.1074/jbc.ra119.007831] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 02/20/2019] [Indexed: 11/06/2022] Open
Abstract
Glucuronoyl esterases (GEs) catalyze the cleavage of ester linkages found between lignin and glucuronic acid moieties on glucuronoxylan in plant biomass. As such, GEs represent promising biochemical tools in industrial processing of these recalcitrant resources. However, details on how GEs interact with their natural substrates are sparse, calling for thorough structure-function studies. Presented here is the structure and biochemical characterization of a GE, TtCE15A, from the bacterium Teredinibacter turnerae, a symbiont of wood-boring shipworms. To gain deeper insight into enzyme-substrate interactions, inhibition studies were performed with both the WT TtCE15A and variants in which we, by using site-directed mutagenesis, substituted residues suggested to have key roles in binding to or interacting with the aromatic and carbohydrate structures of its uronic acid ester substrates. Our results support the hypothesis that two aromatic residues (Phe-174 and Trp-376), conserved in bacterial GEs, interact with aromatic and carbohydrate structures of these substrates in the enzyme active site, respectively. The solved crystal structure of TtCE15A revealed features previously not observed in either fungal or bacterial GEs, with a large inserted N-terminal region neighboring the active site and a differently positioned residue of the catalytic triad. The findings highlight key interactions between GEs and complex lignin-carbohydrate ester substrates and advance our understanding of the substrate specificities of these enzymes in biomass conversion.
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Affiliation(s)
- Jenny Arnling Bååth
- From the Wallenberg Wood Science Center, Division of Industrial Biotechnology, Department of Biology and Biological Engineering, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden and
| | - Scott Mazurkewich
- From the Wallenberg Wood Science Center, Division of Industrial Biotechnology, Department of Biology and Biological Engineering, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden and
| | | | - Lisbeth Olsson
- From the Wallenberg Wood Science Center, Division of Industrial Biotechnology, Department of Biology and Biological Engineering, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden and
| | - Leila Lo Leggio
- Department of Chemistry, University of Copenhagen, DK-2100 Copenhagen, Denmark
| | - Johan Larsbrink
- From the Wallenberg Wood Science Center, Division of Industrial Biotechnology, Department of Biology and Biological Engineering, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden and
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17
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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: 1.3] [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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18
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Sista Kameshwar AK, Qin W. Structural and functional properties of pectin and lignin–carbohydrate complexes de-esterases: a review. BIORESOUR BIOPROCESS 2018. [DOI: 10.1186/s40643-018-0230-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
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19
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Lin MI, Hiyama A, Kondo K, Nagata T, Katahira M. Classification of fungal glucuronoyl esterases (FGEs) and characterization of two new FGEs from Ceriporiopsis subvermispora and Pleurotus eryngii. Appl Microbiol Biotechnol 2018; 102:9635-9645. [PMID: 30232535 DOI: 10.1007/s00253-018-9318-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Revised: 07/21/2018] [Accepted: 08/08/2018] [Indexed: 11/29/2022]
Abstract
Fungal glucuronoyl esterases (FGEs) catalyze cleavage of the ester bond connecting a lignin alcohol to the xylan-bound 4-O-methyl-D-glucuronic acid of glucuronoxylans. Thus, FGEs are capable of degrading lignin-carbohydrate complexes and have potential for biotechnological applications toward woody biomass utilization. Therefore, identification and characterization of new FGEs are of critical importance. Firstly, in this study, we built a phylogenetic tree from almost 400 putative FGEs obtained on BLAST analysis and defined six main clades. In the phylogenetic tree, all the putative FGEs of ascomycetes cluster in clades I to IV, and most of the putative FGEs of basidiomycetes (B-FGEs) cluster in clades V to VI. Interestingly, several B-FGEs were found to cluster in clade II; most FGEs of clade II were found to have higher theoretical isoelectric points than those in the other five clades. To gain an insight into the putative FGEs in the clades that have not been characterized yet, we chose the FGEs of Ceriporiopsis subvermispora (CsGE) and Pleurotus eryngii (PeGE), which belong to clades V and II, respectively. The catalytic domains of both CsGE and PeGE were successfully expressed using Pichia pastoris, and then purified. Benzyl glucuronic acid was used as a substrate to confirm the activities of the CsGE and PeGE, and the hydrolyzed product, glucuronic acid, was quantified spectrophotometrically. Both CsGE and PeGE clearly exhibited the esterase activity. Additionally, we demonstrated that PeGE exhibits high tolerance toward several denaturing agents, which may make it a potentially more applicable enzyme.
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Affiliation(s)
- Meng-I Lin
- Institute of Advanced Energy, Kyoto University, Kyoto, 611-0011, Japan.,Graduate School of Energy Science, Kyoto University, Kyoto, 611-0011, Japan
| | - Akiho Hiyama
- Graduate School of Energy Science, Kyoto University, Kyoto, 611-0011, Japan
| | - Keiko Kondo
- Institute of Advanced Energy, Kyoto University, Kyoto, 611-0011, Japan
| | - Takashi Nagata
- Institute of Advanced Energy, Kyoto University, Kyoto, 611-0011, Japan. .,Graduate School of Energy Science, Kyoto University, Kyoto, 611-0011, Japan.
| | - Masato Katahira
- Institute of Advanced Energy, Kyoto University, Kyoto, 611-0011, Japan. .,Graduate School of Energy Science, Kyoto University, Kyoto, 611-0011, Japan.
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20
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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: 22] [Impact Index Per Article: 3.1] [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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21
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Huynh HH, Ishii N, Matsuo I, Arioka M. A novel glucuronoyl esterase from Aspergillus fumigatus-the role of conserved Lys residue in the preference for 4-O-methyl glucuronoyl esters. Appl Microbiol Biotechnol 2018; 102:2191-2201. [PMID: 29332217 DOI: 10.1007/s00253-018-8739-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Revised: 11/30/2017] [Accepted: 12/12/2017] [Indexed: 11/26/2022]
Abstract
Cellulose in plant cell walls is mainly covered by hemicellulose and lignin, and thus efficient removal of these components is thought to be a key step in the optimal utilization of lignocellulose. The recently discovered carbohydrate esterase (CE) 15 family of glucuronoyl esterases (GEs) which cleave the linkages between the free carboxyl group of D-glucuronic acid in hemicellulose and the benzyl groups in lignin residues could contribute to this process. Herein, we report the identification, functional expression, and enzymatic characterization of a GE, AfGE, from the filamentous fungus Aspergillus fumigatus. AfGE was heterologously expressed in Aspergillus oryzae, and the purified enzyme displayed the ability to degrade the synthetic substrates mimicking the ester linkage between hemicellulose and lignin. AfGE is a potentially industrially applicable enzyme due to its characteristic as a thermophilic enzyme with the favorable temperature of 40-50 °C at pH 5. Molecular modeling and site-directed mutagenesis studies of AfGE demonstrated that Lys209 plays an important role in the preference for the substrates containing 4-O-methyl group in the glucopyranose ring.
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Affiliation(s)
- Hung Hiep Huynh
- Department of Biotechnology, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan
| | - Nozomi Ishii
- Department of Chemistry and Chemical Biology, Gunma University, Maebashi, Japan
| | - Ichiro Matsuo
- Department of Chemistry and Chemical Biology, Gunma University, Maebashi, Japan
| | - Manabu Arioka
- Department of Biotechnology, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo, 113-8657, Japan.
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22
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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: 37] [Impact Index Per Article: 5.3] [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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23
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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. BIOTECHNOLOGY FOR BIOFUELS 2018; 11:213. [PMID: 30083226 PMCID: PMC6069808 DOI: 10.1186/s13068-018-1213-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [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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24
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Dilokpimol A, Mäkelä MR, Cerullo G, Zhou M, Varriale S, Gidijala L, Brás JL, Jütten P, Piechot A, Verhaert R, Faraco V, Hilden KS, de Vries RP. Fungal glucuronoyl esterases: Genome mining based enzyme discovery and biochemical characterization. N Biotechnol 2018; 40:282-287. [DOI: 10.1016/j.nbt.2017.10.003] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Revised: 08/24/2017] [Accepted: 10/11/2017] [Indexed: 10/18/2022]
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25
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De Santi C, Gani OA, Helland R, Williamson A. Structural insight into a CE15 esterase from the marine bacterial metagenome. Sci Rep 2017; 7:17278. [PMID: 29222424 PMCID: PMC5722869 DOI: 10.1038/s41598-017-17677-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 11/28/2017] [Indexed: 12/02/2022] Open
Abstract
The family 15 carbohydrate esterase (CE15) MZ0003, which derives from a marine Arctic metagenome, has a broader substrate scope than other members of this family. Here we report the crystal structure of MZ0003, which reveals that residues comprising the catalytic triad differ from previously-characterized fungal homologs, and resolves three large loop regions that are unique to this bacterial sub-clade. The catalytic triad of the bacterial CE15, which includes Asp 332 as its third member, closely resembles that of family 1 carbohydrate esterases (CE1), despite the overall lower structural similarity with members of this family. Two of the three loop regions form a subdomain that deepens the active site pocket and includes several basic residues that contribute to the high positive charge surrounding the active site. Docking simulations predict specific interactions with the sugar moiety of glucuronic-acid substrates, and with aromatically-substituted derivatives that serve as model compounds for the lignin-carbohydrate complex of plant cell walls. Molecular dynamics simulations indicate considerable flexibility of the sub-domain in the substrate-bound form, suggesting plasticity to accommodate different substrates is possible. The findings from this first reported structure of a bacterial member of the CE15 family provide insight into the basis of its broader substrate specificity.
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Affiliation(s)
- Concetta De Santi
- Department of Chemistry, UiT The Arctic University of Norway, Tromsø, N-9037, Norway
| | - Osman Absm Gani
- Department of Chemistry, UiT The Arctic University of Norway, Tromsø, N-9037, Norway
| | - Ronny Helland
- NorStruct, Department of Chemistry, UiT The Arctic University of Norway, Tromsø, N-9037, Norway
| | - Adele Williamson
- Department of Chemistry, UiT The Arctic University of Norway, Tromsø, N-9037, Norway.
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26
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Singh MK, Shivakumaraswamy S, Gummadi SN, Manoj N. Role of an N-terminal extension in stability and catalytic activity of a hyperthermostable α/β hydrolase fold esterase. Protein Eng Des Sel 2017; 30:559-570. [PMID: 28967962 DOI: 10.1093/protein/gzx049] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Accepted: 08/25/2017] [Indexed: 12/15/2022] Open
Abstract
The carbohydrate esterase family 7 (CE7) enzymes catalyze the deacetylation of acetyl esters of a broad range of alcohols and is unique in its activity towards cephalosporin C. The CE7 fold contains a conserved N-terminal extension that distinguishes it from the canonical α/β hydrolase fold. The hexameric quaternary structure indicates that the N-terminus may affect activity and specificity by controlling access of substrates to the buried active sites via an entrance tunnel. In this context, we characterized the catalytic parameters, conformation and thermal stability of two truncation variants lacking four and ten residues of the N-terminal region of the hyperthermostable Thermotoga maritima CE7 acetyl esterase (TmAcE). The truncations did not affect the secondary structure or the fold but modulated the oligomerization dynamics. A modest increase was observed in substrate specificity for acetylated xylose compared with acetylated glucose. A drastic reduction of ~30-40°C in the optimum temperature for activity of the variants indicated lower thermal stability. The loss of hyperthermostability appears to be an indirect effect associated with an increase in the conformational flexibility of an otherwise rigid neighboring loop containing a catalytic triad residue. The results suggest that the N-terminal extension was evolutionarily selected to preserve the stability of the enzyme.
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Affiliation(s)
- Mrityunjay K Singh
- Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences Indian Institute of Technology Madras, Chennai 600036, India
| | - Santosh Shivakumaraswamy
- Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences Indian Institute of Technology Madras, Chennai 600036, India
| | - Sathyanarayana N Gummadi
- Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences Indian Institute of Technology Madras, Chennai 600036, India
| | - Narayanan Manoj
- Department of Biotechnology, Bhupat and Jyoti Mehta School of Biosciences Indian Institute of Technology Madras, Chennai 600036, India
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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: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [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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28
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Agger JW, Busk PK, Pilgaard B, Meyer AS, Lange L. A New Functional Classification of Glucuronoyl Esterases by Peptide Pattern Recognition. Front Microbiol 2017; 8:309. [PMID: 28293230 PMCID: PMC5329029 DOI: 10.3389/fmicb.2017.00309] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Accepted: 02/14/2017] [Indexed: 12/21/2022] Open
Abstract
Glucuronoyl esterases are a novel type of enzymes believed to catalyze the hydrolysis of ester linkages between lignin and glucuronoxylan in lignocellulosic biomass, linkages known as lignin carbohydrate complexes. These complexes contribute to the recalcitrance of lignocellulose. Glucuronoyl esterases are a part of the microbial machinery for lignocellulose degradation and coupling their role to the occurrence of lignin carbohydrate complexes in biomass is a desired research goal. Glucuronoyl esterases have been assigned to CAZymes family 15 of carbohydrate esterases, but only few examples of characterized enzymes exist and the exact activity is still uncertain. Here peptide pattern recognition is used as a bioinformatic tool to identify and group new CE15 proteins that are likely to have glucuronoyl esterase activity. 1024 CE15-like sequences were drawn from GenBank and grouped into 24 groups. Phylogenetic analysis of these groups made it possible to pinpoint groups of putative fungal and bacterial glucuronoyl esterases and their sequence variation. Moreover, a number of groups included previously undescribed CE15-like sequences that are distinct from the glucuronoyl esterases and may possibly have different esterase activity. Hence, the CE15 family is likely to comprise other enzyme functions than glucuronoyl esterase alone. Gene annotation in a variety of fungal and bacterial microorganisms showed that coprophilic fungi are rich and diverse sources of CE15 proteins. Combined with the lifestyle and habitat of coprophilic fungi, they are predicted to be excellent candidates for finding new glucuronoyl esterase genes.
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Affiliation(s)
- Jane W Agger
- Center for BioProcess Engineering, Department of Chemical and Biochemical Engineering, Technical University of Denmark Lyngby, Denmark
| | - Peter K Busk
- Center for BioProcess Engineering, Department of Chemical and Biochemical Engineering, Technical University of Denmark Lyngby, Denmark
| | - Bo Pilgaard
- Center for BioProcess Engineering, Department of Chemical and Biochemical Engineering, Technical University of Denmark Lyngby, Denmark
| | - Anne S Meyer
- Center for BioProcess Engineering, Department of Chemical and Biochemical Engineering, Technical University of Denmark Lyngby, Denmark
| | - Lene Lange
- Center for BioProcess Engineering, Department of Chemical and Biochemical Engineering, Technical University of Denmark Lyngby, Denmark
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Abstract
A carbohydrate esterase called glucuronoyl esterase (GE) was discovered 10 years ago in a cellulolytic system of the wood-rotting fungus Schizophyllum commune Genes coding for GEs were subsequently found in a number of microbial genomes, and a new family of carbohydrate esterases (CE15) has been established. The multidomain structures of GEs, together with their catalytic properties on artificial substrates and positive effect on enzymatic saccharification of plant biomass, led to the view that the esterases evolved for hydrolysis of the ester linkages between 4-O-methyl-d-glucuronic acid of plant glucuronoxylans and lignin alcohols, one of the crosslinks in the plant cell walls. This idea of the function of GEs is further supported by the effects of cloning of fungal GEs in plants and by very recently reported evidence for changes in the size of isolated lignin-carbohydrate complexes due to uronic acid de-esterification. These facts make GEs interesting candidates for biotechnological applications in plant biomass processing and genetic modification of plants. This article is a brief summary of current knowledge of these relatively recent and unexplored esterases.
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Fraňová L, Puchart V, Biely P. β-Glucuronidase-coupled assays of glucuronoyl esterases. Anal Biochem 2016; 510:114-119. [PMID: 27452816 DOI: 10.1016/j.ab.2016.07.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Revised: 06/20/2016] [Accepted: 07/20/2016] [Indexed: 12/22/2022]
Abstract
Glucuronoyl esterases (GEs) are microbial enzymes with potential to cleave the ester bonds between lignin alcohols and xylan-bound 4-O-methyl-d-glucuronic acid in plant cell walls. This activity renders GEs attractive research targets for biotechnological applications. One of the factors impeding the progress in GE research is the lack of suitable substrates. In this work, we report a facile preparation of methyl esters of chromogenic 4-nitrophenyl and 5-bromo-4-chloro-3-indolyl β-D-glucuronides for qualitative and quantitative GE assay coupled with β-glucuronidase as the auxiliary enzyme. The indolyl derivative affording a blue indigo-type product is suitable for rapid and sensitive assay of GE in commercial preparations as well as for high throughput screening of microorganisms and genomic and metagenomic libraries.
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Affiliation(s)
- Lucia Fraňová
- Institute of Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, SK-845 38 Bratislava, Slovak Republic.
| | - Vladimír Puchart
- Institute of Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, SK-845 38 Bratislava, Slovak Republic.
| | - Peter Biely
- Institute of Chemistry, Slovak Academy of Sciences, Dúbravská cesta 9, SK-845 38 Bratislava, Slovak Republic.
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De Santi C, Willassen NP, Williamson A. Biochemical Characterization of a Family 15 Carbohydrate Esterase from a Bacterial Marine Arctic Metagenome. PLoS One 2016; 11:e0159345. [PMID: 27433797 PMCID: PMC4951047 DOI: 10.1371/journal.pone.0159345] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Accepted: 06/30/2016] [Indexed: 12/20/2022] Open
Abstract
Background The glucuronoyl esterase enzymes of wood-degrading fungi (Carbohydrate Esterase family 15; CE15) form part of the hemicellulolytic and cellulolytic enzyme systems that break down plant biomass, and have possible applications in biotechnology. Homologous enzymes are predicted in the genomes of several bacteria, however these have been much less studied than their fungal counterparts. Here we describe the recombinant production and biochemical characterization of a bacterial CE15 enzyme denoted MZ0003, which was identified by in silico screening of a prokaryotic metagenome library derived from marine Arctic sediment. MZ0003 has high similarity to several uncharacterized gene products of polysaccharide-degrading bacterial species, and phylogenetic analysis indicates a deep evolutionary split between these CE15s and fungal homologs. Results MZ0003 appears to differ from previously-studied CE15s in some aspects. Some glucuronoyl esterase activity could be measured by qualitative thin-layer chromatography which confirms its assignment as a CE15, however MZ0003 can also hydrolyze a range of other esters, including p-nitrophenyl acetate, which is not acted upon by some fungal homologs. The structure of MZ0003 also appears to differ as it is predicted to have several large loop regions that are absent in previously studied CE15s, and a combination of homology-based modelling and site-directed mutagenesis indicate its catalytic residues deviate from the conserved Ser-His-Glu triad of many fungal CE15s. Taken together, these results indicate that potentially unexplored diversity exists among bacterial CE15s, and this may be accessed by investigation of the microbial metagenome. The combination of low activity on typical glucuronoyl esterase substrates, and the lack of glucuronic acid esters in the marine environment suggest that the physiological substrate of MZ0003 and its homologs is likely to be different from that of related fungal enzymes.
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Affiliation(s)
- Concetta De Santi
- The Norwegian Structural Biology Centre, Department of Chemistry, UiT—The Arctic University of Norway, Tromsø, Norway
| | - Nils Peder Willassen
- The Norwegian Structural Biology Centre, Department of Chemistry, UiT—The Arctic University of Norway, Tromsø, Norway
| | - Adele Williamson
- The Norwegian Structural Biology Centre, Department of Chemistry, UiT—The Arctic University of Norway, Tromsø, Norway
- * E-mail:
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Bischof RH, Ramoni J, Seiboth B. Cellulases and beyond: the first 70 years of the enzyme producer Trichoderma reesei. Microb Cell Fact 2016; 15:106. [PMID: 27287427 PMCID: PMC4902900 DOI: 10.1186/s12934-016-0507-6] [Citation(s) in RCA: 320] [Impact Index Per Article: 35.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2016] [Accepted: 06/01/2016] [Indexed: 11/10/2022] Open
Abstract
More than 70 years ago, the filamentous ascomycete Trichoderma reesei was isolated on the Solomon Islands due to its ability to degrade and thrive on cellulose containing fabrics. This trait that relies on its secreted cellulases is nowadays exploited by several industries. Most prominently in biorefineries which use T. reesei enzymes to saccharify lignocellulose from renewable plant biomass in order to produce biobased fuels and chemicals. In this review we summarize important milestones of the development of T. reesei as the leading production host for biorefinery enzymes, and discuss emerging trends in strain engineering. Trichoderma reesei has very recently also been proposed as a consolidated bioprocessing organism capable of direct conversion of biopolymeric substrates to desired products. We therefore cover this topic by reviewing novel approaches in metabolic engineering of T. reesei.
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Affiliation(s)
- Robert H Bischof
- Austrian Centre of Industrial Biotechnology (ACIB) GmbH c/o Institute of Chemical Engineering, TU Wien, Gumpendorferstraße 1a, 1060, Vienna, Austria
| | - Jonas Ramoni
- Molecular Biotechnology, Research Area Biochemical Technology, Institute of Chemical Engineering, TU Wien, Gumpendorferstraße 1a, 1060, Vienna, Austria
| | - Bernhard Seiboth
- Austrian Centre of Industrial Biotechnology (ACIB) GmbH c/o Institute of Chemical Engineering, TU Wien, Gumpendorferstraße 1a, 1060, Vienna, Austria. .,Molecular Biotechnology, Research Area Biochemical Technology, Institute of Chemical Engineering, TU Wien, Gumpendorferstraße 1a, 1060, Vienna, Austria.
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34
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An extended loop in CE7 carbohydrate esterase family is dispensable for oligomerization but required for activity and thermostability. J Struct Biol 2016; 194:434-45. [DOI: 10.1016/j.jsb.2016.04.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2016] [Revised: 04/07/2016] [Accepted: 04/13/2016] [Indexed: 11/20/2022]
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35
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d'Errico C, Börjesson J, Ding H, Krogh KB, Spodsberg N, Madsen R, Monrad RN. Improved biomass degradation using fungal glucuronoyl—esterases—hydrolysis of natural corn fiber substrate. J Biotechnol 2016; 219:117-23. [DOI: 10.1016/j.jbiotec.2015.12.024] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Revised: 11/26/2015] [Accepted: 12/15/2015] [Indexed: 11/26/2022]
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36
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Huynh HH, Arioka M. Functional expression and characterization of a glucuronoyl esterase from the fungus Neurospora crassa: identification of novel consensus sequences containing the catalytic triad. J GEN APPL MICROBIOL 2016; 62:217-224. [DOI: 10.2323/jgam.2016.03.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Affiliation(s)
| | - Manabu Arioka
- Department of Biotechnology, The University of Tokyo
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37
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Sunner H, Charavgi MD, Olsson L, Topakas E, Christakopoulos P. Glucuronoyl Esterase Screening and Characterization Assays Utilizing Commercially Available Benzyl Glucuronic Acid Ester. Molecules 2015; 20:17807-17. [PMID: 26404219 PMCID: PMC6332307 DOI: 10.3390/molecules201017807] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Revised: 09/10/2015] [Accepted: 09/17/2015] [Indexed: 12/04/2022] Open
Abstract
Research on glucuronoyl esterases (GEs) has been hampered by the lack of enzyme assays based on easily obtainable substrates. While benzyl d-glucuronic acid ester (BnGlcA) is a commercially available substrate that can be used for GE assays, several considerations regarding substrate instability, limited solubility and low apparent affinities should be made. In this work we discuss the factors that are important when using BnGlcA for assaying GE activity and show how these can be applied when designing BnGlcA-based GE assays for different applications: a thin-layer chromatography assay for qualitative activity detection, a coupled-enzyme spectrophotometric assay that can be used for high-throughput screening or general activity determinations and a HPLC-based detection method allowing kinetic determinations. The three-level experimental procedure not merely facilitates routine, fast and simple biochemical characterizations but it can also give rise to the discovery of different GEs through an extensive screening of heterologous Genomic and Metagenomic expression libraries.
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Affiliation(s)
- Hampus Sunner
- Industrial Biotechnology, Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg SE-412 96, Sweden.
- Wallenberg Wood Science Centre, Teknikringen 56-58, Stockholm SE-100 44, Sweden.
| | - Maria-Despoina Charavgi
- Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens, 5 Iroon Polytechniou Str., Zografou Campus, Athens 15780, Greece.
| | - Lisbeth Olsson
- Industrial Biotechnology, Department of Biology and Biological Engineering, Chalmers University of Technology, Gothenburg SE-412 96, Sweden.
- Wallenberg Wood Science Centre, Teknikringen 56-58, Stockholm SE-100 44, Sweden.
| | - Evangelos Topakas
- Biotechnology Laboratory, School of Chemical Engineering, National Technical University of Athens, 5 Iroon Polytechniou Str., Zografou Campus, Athens 15780, Greece.
| | - Paul Christakopoulos
- Biochemical Process Engineering, Division of Chemical Engineering, Department of Civil, Environmental and Natural Resources Engineering, Luleå University of Technology, Luleå SE-971 87, Sweden.
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38
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Biely P, Malovíková A, Uhliariková I, Li XL, Wong DWS. Glucuronoyl esterases are active on the polymeric substrate methyl esterified glucuronoxylan. FEBS Lett 2015. [PMID: 26216754 DOI: 10.1016/j.febslet.2015.07.019] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Alkali extracted beechwood glucuronoxylan methyl ester prepared by esterification of 4-O-methyl-D-glucuronic acid side residues by methanol was found to serve as substrate of microbial glucuronoyl esterases from Ruminococcus flavefaciens, Schizophyllum commune and Trichoderma reesei. The enzymatic deesterification was monitored by (1)H NMR spectroscopy and evaluated on the basis of the decrease of the signal of the ester methyl group and increase of the signal of methanol. The results show for the first time the action of enzymes on polymeric substrate, which imitates more closely the natural substrate in plant cell walls than the low molecular mass artificial substrates used up to present.
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Affiliation(s)
- Peter Biely
- Institute of Chemistry, Slovak Academy of Sciences, 84538 Bratislava, Slovakia.
| | - Anna Malovíková
- Institute of Chemistry, Slovak Academy of Sciences, 84538 Bratislava, Slovakia
| | - Iveta Uhliariková
- Institute of Chemistry, Slovak Academy of Sciences, 84538 Bratislava, Slovakia
| | | | - Dominic W S Wong
- Western Regional Research Center, USDA-ARS, Albany, 94710 CA, USA
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d'Errico C, Jørgensen JO, Krogh KBRM, Spodsberg N, Madsen R, Monrad RN. Enzymatic degradation of lignin-carbohydrate complexes (LCCs): model studies using a fungal glucuronoyl esterase from Cerrena unicolor. Biotechnol Bioeng 2015; 112:914-22. [PMID: 25425346 DOI: 10.1002/bit.25508] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2014] [Revised: 11/14/2014] [Accepted: 11/17/2014] [Indexed: 11/09/2022]
Abstract
Lignin-carbohydrate complexes (LCCs) are believed to influence the recalcitrance of lignocellulosic plant material preventing optimal utilization of biomass in e.g. forestry, feed and biofuel applications. The recently emerged carbohydrate esterase (CE) 15 family of glucuronoyl esterases (GEs) has been proposed to degrade ester LCC bonds between glucuronic acids in xylans and lignin alcohols thereby potentially improving delignification of lignocellulosic biomass when applied in conjunction with other cellulases, hemicellulases and oxidoreductases. Herein, we report the synthesis of four new GE model substrates comprising α- and ɣ-arylalkyl esters representative of the lignin part of naturally occurring ester LCCs as well as the cloning and purification of a novel GE from Cerrena unicolor (CuGE). Together with a known GE from Schizophyllum commune (ScGE), CuGE was biochemically characterized by means of Michaelis-Menten kinetics with respect to substrate specificity using the synthesized compounds. For both enzymes, a strong preference for 4-O-methyl glucuronoyl esters rather than unsubstituted glucuronoyl esters was observed. Moreover, we found that α-arylalkyl esters of methyl α-D-glucuronic acid are more easily cleaved by GEs than their corresponding ɣ-arylalkyl esters. Furthermore, our results suggest a preference of CuGE for glucuronoyl esters of bulky alcohols supporting the suggested biological action of GEs on LCCs. The synthesis of relevant GE model substrates presented here may provide a valuable tool for the screening, selection and development of industrially relevant GEs for delignification of biomass.
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Affiliation(s)
- Clotilde d'Errico
- Department of Chemistry, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark
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40
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Enzymatic synthesis of model substrates recognized by glucuronoyl esterases from Podospora anserina and Myceliophthora thermophila. Appl Microbiol Biotechnol 2014; 98:5507-16. [DOI: 10.1007/s00253-014-5542-9] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Revised: 01/11/2014] [Accepted: 01/13/2014] [Indexed: 11/25/2022]
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41
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Adams PD, Baker D, Brunger AT, Das R, DiMaio F, Read RJ, Richardson DC, Richardson JS, Terwilliger TC. Advances, interactions, and future developments in the CNS, Phenix, and Rosetta structural biology software systems. Annu Rev Biophys 2013; 42:265-87. [PMID: 23451892 DOI: 10.1146/annurev-biophys-083012-130253] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Advances in our understanding of macromolecular structure come from experimental methods, such as X-ray crystallography, and also computational analysis of the growing number of atomic models obtained from such experiments. The later analyses have made it possible to develop powerful tools for structure prediction and optimization in the absence of experimental data. In recent years, a synergy between these computational methods for crystallographic structure determination and structure prediction and optimization has begun to be exploited. We review some of the advances in the algorithms used for crystallographic structure determination in the Phenix and Crystallography & NMR System software packages and describe how methods from ab initio structure prediction and refinement in Rosetta have been applied to challenging crystallographic problems. The prospects for future improvement of these methods are discussed.
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Affiliation(s)
- Paul D Adams
- Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
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42
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Charavgi MD, Dimarogona M, Topakas E, Christakopoulos P, Chrysina ED. The structure of a novel glucuronoyl esterase from Myceliophthora thermophila gives new insights into its role as a potential biocatalyst. ACTA CRYSTALLOGRAPHICA SECTION D: BIOLOGICAL CRYSTALLOGRAPHY 2012; 69:63-73. [PMID: 23275164 DOI: 10.1107/s0907444912042400] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2012] [Accepted: 10/10/2012] [Indexed: 11/10/2022]
Abstract
The increasing demand for the development of efficient biocatalysts is a consequence of their broad industrial applications. Typical difficulties that are encountered during their exploitation in a variety of processes are interconnected with factors such as temperature, pH, product inhibitors etc. To eliminate these, research has been directed towards the identification of new enzymes that would comply with the required standards. To this end, the recently discovered glucuronoyl esterases (GEs) are an enigmatic family within the carbohydrate esterase (CE) family. Structures of the thermophilic StGE2 esterase from Myceliophthora thermophila (synonym Sporotrichum thermophile), a member of the CE15 family, and its S213A mutant were determined at 1.55 and 1.9 Å resolution, respectively. The first crystal structure of the S213A mutant in complex with a substrate analogue, methyl 4-O-methyl-β-D-glucopyranuronate, was determined at 2.35 Å resolution. All of the three-dimensional protein structures have an α/β-hydrolase fold with a three-layer αβα-sandwich architecture and a Rossmann topology and comprise one molecule per asymmetric unit. These are the first crystal structures of a thermophilic GE both in an unliganded form and bound to a substrate analogue, thus unravelling the organization of the catalytic triad residues and their neighbours lining the active site. The knowledge derived offers novel insights into the key structural elements that drive the hydrolysis of glucuronic acid esters.
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Affiliation(s)
- Maria Despoina Charavgi
- Institute of Biology, Medicinal Chemistry and Biotechnology, National Hellenic Research Foundation, Athens, Greece
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43
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Tsai AYL, Canam T, Gorzsás A, Mellerowicz EJ, Campbell MM, Master ER. Constitutive expression of a fungal glucuronoyl esterase in Arabidopsis reveals altered cell wall composition and structure. PLANT BIOTECHNOLOGY JOURNAL 2012; 10:1077-87. [PMID: 22924998 DOI: 10.1111/j.1467-7652.2012.00735.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
A family 15 carbohydrate esterase (CE15) from the white-rot basidiomycete, Phanerochaete carnosa (PcGCE), was transformed into Arabidopsis thaliana Col-0 and was expressed from the constitutive cauliflower mosaic virus 35S promoter. Like other CE15 enzymes, PcGCE hydrolyzed methyl-4-O-methyl-d-glucopyranuronate and could target ester linkages that contribute to lignin-carbohydrate complexes that form in plant cell walls. Three independently transformed Arabidopsis lines were evaluated in terms of nine morphometric parameters, total sugar and lignin composition, cell wall anatomy, enzymatic saccharification and xylan extractability. The transgenic lines consistently displayed a leaf-yellowing phenotype, as well as reduced glucose and xylose content by as much as 30% and 35%, respectively. Histological analysis revealed 50% reduction in cell wall thickness in the interfascicular fibres of transgenic plants, and FT-IR microspectroscopy of interfascicular fibre walls indicated reduction in lignin cross-linking in plants overexpressing PcGCE. Notably, these characteristics could be correlated with improved xylose recovery in transgenic plants, up to 15%. The current analysis represents the first example whereby a fungal glucuronoyl esterase is expressed in Arabidopsis and shows that the promotion of glucuronoyl esterase activity in plants can alter the extent of intermolecular cross-linking within plant cell walls.
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Affiliation(s)
- Alex Y-L Tsai
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON, Canada
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Häkkinen M, Arvas M, Oja M, Aro N, Penttilä M, Saloheimo M, Pakula TM. Re-annotation of the CAZy genes of Trichoderma reesei and transcription in the presence of lignocellulosic substrates. Microb Cell Fact 2012; 11:134. [PMID: 23035824 PMCID: PMC3526510 DOI: 10.1186/1475-2859-11-134] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2012] [Accepted: 09/22/2012] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Trichoderma reesei is a soft rot Ascomycota fungus utilised for industrial production of secreted enzymes, especially lignocellulose degrading enzymes. About 30 carbohydrate active enzymes (CAZymes) of T. reesei have been biochemically characterised. Genome sequencing has revealed a large number of novel candidates for CAZymes, thus increasing the potential for identification of enzymes with novel activities and properties. Plenty of data exists on the carbon source dependent regulation of the characterised hydrolytic genes. However, information on the expression of the novel CAZyme genes, especially on complex biomass material, is very limited. RESULTS In this study, the CAZyme gene content of the T. reesei genome was updated and the annotations of the genes refined using both computational and manual approaches. Phylogenetic analysis was done to assist the annotation and to identify functionally diversified CAZymes. The analyses identified 201 glycoside hydrolase genes, 22 carbohydrate esterase genes and five polysaccharide lyase genes. Updated or novel functional predictions were assigned to 44 genes, and the phylogenetic analysis indicated further functional diversification within enzyme families or groups of enzymes. GH3 β-glucosidases, GH27 α-galactosidases and GH18 chitinases were especially functionally diverse. The expression of the lignocellulose degrading enzyme system of T. reesei was studied by cultivating the fungus in the presence of different inducing substrates and by subjecting the cultures to transcriptional profiling. The substrates included both defined and complex lignocellulose related materials, such as pretreated bagasse, wheat straw, spruce, xylan, Avicel cellulose and sophorose. The analysis revealed co-regulated groups of CAZyme genes, such as genes induced in all the conditions studied and also genes induced preferentially by a certain set of substrates. CONCLUSIONS In this study, the CAZyme content of the T. reesei genome was updated, the discrepancies between the different genome versions and published literature were removed and the annotation of many of the genes was refined. Expression analysis of the genes gave information on the enzyme activities potentially induced by the presence of the different substrates. Comparison of the expression profiles of the CAZyme genes under the different conditions identified co-regulated groups of genes, suggesting common regulatory mechanisms for the gene groups.
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Affiliation(s)
- Mari Häkkinen
- VTT Technical Research Centre of Finland, Tietotie 2, Espoo, FI-02044, VTT, Finland.
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Functional Cloning and Expression of the Schizophyllum commune Glucuronoyl Esterase Gene and Characterization of the Recombinant Enzyme. BIOTECHNOLOGY RESEARCH INTERNATIONAL 2012; 2012:951267. [PMID: 22844600 PMCID: PMC3398583 DOI: 10.1155/2012/951267] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/19/2012] [Revised: 05/07/2012] [Accepted: 05/09/2012] [Indexed: 11/23/2022]
Abstract
The gene encoding Schizophyllum commune glucuronoyl esterase was identified in the scaffold 17 of the genome, containing two introns of 50 bp and 48 bp, with a transcript sequence of 1179 bp. The gene was synthesized and cloned into Pichia pastoris expression vector pGAPZα to achieve constitutive expression and secretion of the recombinant enzyme in soluble active form. The purified protein was 53 kD with glycosylation and had an acidic pI of 3.7. Activity analysis on several uronic acids and their derivatives suggests that the enzyme recognized only esters of 4-O-methyl-D-glucuronic acid derivatives, even with a 4-nitrophenyl aglycon but did not hydrolyze the ester of D-galacturonic acid. The kinetic values were Km 0.25 mM, Vmax 16.3 μM·min−1, and kcat 9.27 s−1 with 4-nitrophenyl 2-O-(methyl 4-O-methyl-α-D-glucopyranosyluronate)-β-D-xylopyranoside as the substrate.
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Terwilliger TC, Read RJ, Adams PD, Brunger AT, Afonine PV, Grosse-Kunstleve RW, Hung LW. Improved crystallographic models through iterated local density-guided model deformation and reciprocal-space refinement. ACTA CRYSTALLOGRAPHICA. SECTION D, BIOLOGICAL CRYSTALLOGRAPHY 2012; 68:861-70. [PMID: 22751672 PMCID: PMC3388814 DOI: 10.1107/s0907444912015636] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/14/2011] [Accepted: 04/10/2012] [Indexed: 11/14/2022]
Abstract
An approach is presented for addressing the challenge of model rebuilding after molecular replacement in cases where the placed template is very different from the structure to be determined. The approach takes advantage of the observation that a template and target structure may have local structures that can be superimposed much more closely than can their complete structures. A density-guided procedure for deformation of a properly placed template is introduced. A shift in the coordinates of each residue in the structure is calculated based on optimizing the match of model density within a 6 Å radius of the center of that residue with a prime-and-switch electron-density map. The shifts are smoothed and applied to the atoms in each residue, leading to local deformation of the template that improves the match of map and model. The model is then refined to improve the geometry and the fit of model to the structure-factor data. A new map is then calculated and the process is repeated until convergence. The procedure can extend the routine applicability of automated molecular replacement, model building and refinement to search models with over 2 Å r.m.s.d. representing 65-100% of the structure.
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Affiliation(s)
- Thomas C Terwilliger
- Bioscience Division and Los Alamos Institutes, Los Alamos National Laboratory, Los Alamos, NM 87545, USA.
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