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Chorozian K, Karnaouri A, Tryfona T, Kondyli NG, Karantonis A, Topakas E. Characterization of a novel AA16 lytic polysaccharide monooxygenase from Thermothelomyces thermophilus and comparison of biochemical properties with an LPMO from AA9 family. Carbohydr Polym 2024; 342:122387. [PMID: 39048228 DOI: 10.1016/j.carbpol.2024.122387] [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: 02/21/2024] [Revised: 06/01/2024] [Accepted: 06/07/2024] [Indexed: 07/27/2024]
Abstract
Lytic polysaccharide monooxygenases (LPMOs) are copper-dependent enzymes which are categorized in the CAZy database under auxiliary activities families AA9-11, 13, 14-17. Secreted by various microorganisms, they play a crucial role in carbon recycling, particularly in fungal saprotrophs. LPMOs oxidize polysaccharides through monooxygenase/peroxygenase activities and exhibit peroxidase and oxidase activities, with variations among different families. AA16, a newly identified LPMO family, is noteworthy due to limited studies on its members, thus rendering the characterization of AA16 enzymes vital for addressing controversies around their functions. This study focused on heterologous expression and biochemical study of an AA16 LPMO from Thermothelomyces thermophilus (formerly known as Myceliophthora thermophila), namely MtLPMO16A. Substrate specificity evaluation of MtLPMO16A showed oxidative cleavage of hemicellulosic substrates and no activity on cellulose, accompanied by a strong oxidase activity. A comparative analysis with an LPMO from AA9 family explored correlations between these families, while MtLPMO16A was shown to boost the activity of some AA9 family LPMOs. The results offer new insights into the AA16 family's action mode and microbial hemicellulose decomposition mechanisms in nature.
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Affiliation(s)
- Koar Chorozian
- Ιndustrial Biotechnology & Biocatalysis Group, School of Chemical Engineering, National Technical University of Athens, Zografou Campus, 15772, Greece
| | - Anthi Karnaouri
- Laboratory of General and Agricultural Microbiology, Department of Crop Science, Agricultural University of Athens, Athens 11855, Greece.
| | - Theodora Tryfona
- Department of Biochemistry, School of Biological Sciences, University of Cambridge, Cambridge CB2 1QW, UK
| | - Nefeli Georgaki Kondyli
- Ιndustrial Biotechnology & Biocatalysis Group, School of Chemical Engineering, National Technical University of Athens, Zografou Campus, 15772, Greece; Laboratory of Physical Chemistry and Applied Electrochemistry, School of Chemical Engineering, National Technical University of Athens, Zografou Campus, 15780, Greece
| | - Antonis Karantonis
- Laboratory of Physical Chemistry and Applied Electrochemistry, School of Chemical Engineering, National Technical University of Athens, Zografou Campus, 15780, Greece
| | - Evangelos Topakas
- Ιndustrial Biotechnology & Biocatalysis Group, School of Chemical Engineering, National Technical University of Athens, Zografou Campus, 15772, Greece.
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2
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Koch NG, Budisa N. Evolution of Pyrrolysyl-tRNA Synthetase: From Methanogenesis to Genetic Code Expansion. Chem Rev 2024; 124:9580-9608. [PMID: 38953775 PMCID: PMC11363022 DOI: 10.1021/acs.chemrev.4c00031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2024] [Revised: 05/22/2024] [Accepted: 05/28/2024] [Indexed: 07/04/2024]
Abstract
Over 20 years ago, the pyrrolysine encoding translation system was discovered in specific archaea. Our Review provides an overview of how the once obscure pyrrolysyl-tRNA synthetase (PylRS) tRNA pair, originally responsible for accurately translating enzymes crucial in methanogenic metabolic pathways, laid the foundation for the burgeoning field of genetic code expansion. Our primary focus is the discussion of how to successfully engineer the PylRS to recognize new substrates and exhibit higher in vivo activity. We have compiled a comprehensive list of ncAAs incorporable with the PylRS system. Additionally, we also summarize recent successful applications of the PylRS system in creating innovative therapeutic solutions, such as new antibody-drug conjugates, advancements in vaccine modalities, and the potential production of new antimicrobials.
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Affiliation(s)
- Nikolaj G. Koch
- Department
of Chemistry, Institute of Physical Chemistry, University of Basel, 4058 Basel, Switzerland
- Department
of Biosystems Science and Engineering, ETH
Zurich, 4058 Basel, Switzerland
| | - Nediljko Budisa
- Biocatalysis
Group, Institute of Chemistry, Technische
Universität Berlin, 10623 Berlin, Germany
- Chemical
Synthetic Biology Chair, Department of Chemistry, University of Manitoba, Winnipeg MB R3T 2N2, Canada
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3
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Munzone A, Eijsink VGH, Berrin JG, Bissaro B. Expanding the catalytic landscape of metalloenzymes with lytic polysaccharide monooxygenases. Nat Rev Chem 2024; 8:106-119. [PMID: 38200220 DOI: 10.1038/s41570-023-00565-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/20/2023] [Indexed: 01/12/2024]
Abstract
Lytic polysaccharide monooxygenases (LPMOs) have an essential role in global carbon cycle, industrial biomass processing and microbial pathogenicity by catalysing the oxidative cleavage of recalcitrant polysaccharides. Despite initially being considered monooxygenases, experimental and theoretical studies show that LPMOs are essentially peroxygenases, using a single copper ion and H2O2 for C-H bond oxygenation. Here, we examine LPMO catalysis, emphasizing key studies that have shaped our comprehension of their function, and address side and competing reactions that have partially obscured our understanding. Then, we compare this novel copper-peroxygenase reaction with reactions catalysed by haem iron enzymes, highlighting the different chemistries at play. We conclude by addressing some open questions surrounding LPMO catalysis, including the importance of peroxygenase and monooxygenase reactions in biological contexts, how LPMOs modulate copper site reactivity and potential protective mechanisms against oxidative damage.
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Affiliation(s)
- Alessia Munzone
- UMR1163 Biodiversité et Biotechnologie Fongiques, INRAE, Aix Marseille University, Marseille, France
| | - Vincent G H Eijsink
- Faculty of Chemistry, Biotechnology, and Food Science, The Norwegian University of Life Sciences (NMBU), Ås, Norway
| | - Jean-Guy Berrin
- UMR1163 Biodiversité et Biotechnologie Fongiques, INRAE, Aix Marseille University, Marseille, France
| | - Bastien Bissaro
- UMR1163 Biodiversité et Biotechnologie Fongiques, INRAE, Aix Marseille University, Marseille, France.
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4
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Chorozian K, Karnaouri A, Georgaki-Kondyli N, Karantonis A, Topakas E. Assessing the role of redox partners in TthLPMO9G and its mutants: focus on H 2O 2 production and interaction with cellulose. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2024; 17:19. [PMID: 38303072 PMCID: PMC10835826 DOI: 10.1186/s13068-024-02463-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Accepted: 01/18/2024] [Indexed: 02/03/2024]
Abstract
BACKGROUND The field of enzymology has been profoundly transformed by the discovery of lytic polysaccharide monooxygenases (LPMOs). LPMOs hold a unique role in the natural breakdown of recalcitrant polymers like cellulose and chitin. They are characterized by a "histidine brace" in their active site, known to operate via an O2/H2O2 mechanism and require an electron source for catalytic activity. Although significant research has been conducted in the field, the relationship between these enzymes, their electron donors, and H2O2 production remains complex and multifaceted. RESULTS This study examines TthLPMO9G activity, focusing on its interactions with various electron donors, H2O2, and cellulose substrate interactions. Moreover, the introduction of catalase effectively eliminates H2O2 interference, enabling an accurate evaluation of each donor's efficacy based on electron delivery to the LPMO active site. The introduction of catalase enhances TthLPMO9G's catalytic efficiency, leading to increased cellulose oxidation. The current study provides deeper insights into specific point mutations, illuminating the crucial role of the second coordination sphere histidine at position 140. Significantly, the H140A mutation not only impacted the enzyme's ability to oxidize cellulose, but also altered its interaction with H2O2. This change was manifested in the observed decrease in both oxidase and peroxidase activities. Furthermore, the S28A substitution, selected for potential engagement within the His1-electron donor-cellulose interaction triad, displayed electron donor-dependent alterations in cellulose product patterns. CONCLUSION The interaction of an LPMO with H2O2, electron donors, and cellulose substrate, alongside the impact of catalase, offers deep insights into the intricate interactions occurring at the molecular level within the enzyme. Through rational alterations and substitutions that affect both the first and second coordination spheres of the active site, this study illuminates the enzyme's function. These insights enhance our understanding of the enzyme's mechanisms, providing valuable guidance for future research and potential applications in enzymology and biochemistry.
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Affiliation(s)
- Koar Chorozian
- Industrial Biotechnology & Biocatalysis Group, School of Chemical Engineering, National Technical University of Athens, Zografou Campus, 15772, Athens, Greece
| | - Anthi Karnaouri
- Laboratory of General and Agricultural Microbiology, Department of Crop Science, Agricultural University of Athens, 11855, Athens, Greece
| | - Nefeli Georgaki-Kondyli
- Industrial Biotechnology & Biocatalysis Group, School of Chemical Engineering, National Technical University of Athens, Zografou Campus, 15772, Athens, Greece
| | - Antonis Karantonis
- Laboratory of Physical Chemistry and Applied Electrochemistry, School of Chemical Engineering, National Technical University of Athens, Zografou Campus, 15772, Athens, Greece
| | - Evangelos Topakas
- Industrial Biotechnology & Biocatalysis Group, School of Chemical Engineering, National Technical University of Athens, Zografou Campus, 15772, Athens, Greece.
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5
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Kumar A, Singh A, Sharma VK, Goel A, Kumar A. The upsurge of lytic polysaccharide monooxygenases in biomass deconstruction: characteristic functions and sustainable applications. FEBS J 2024. [PMID: 38291603 DOI: 10.1111/febs.17063] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Revised: 12/19/2023] [Accepted: 01/12/2024] [Indexed: 02/01/2024]
Abstract
Lytic polysaccharide monooxygenases (LPMOs) are one of the emerging classes of copper metalloenzymes that have received considerable attention due to their ability to boost the enzymatic conversion of intractable polysaccharides such as plant cell walls and chitin polymers. LPMOs catalyze the oxidative cleavage of β-1,4-glycosidic bonds using molecular O2 or H2 O2 in the presence of an external electron donor. LPMOs have been classified as an auxiliary active (AA) class of enzymes and, further based on substrate specificity, divided into eight families. Until now, multiple LPMOs from AA9 and AA10 families, mostly from microbial sources, have been investigated; the exact mechanism and structure-function are elusive to date, and recently discovered AA families of LPMOs are just scratched. This review highlights the origin and discovery of the enzyme, nomenclature, three-dimensional protein structure, substrate specificity, copper-dependent reaction mechanism, and different techniques used to determine the product formation through analytical and biochemical methods. Moreover, the diverse functions of proteins in various biological activities such as plant-pathogen/pest interactions, cell wall remodeling, antibiotic sensitivity of biofilms, and production of nanocellulose along with certain obstacles in deconstructing the complex polysaccharides have also been summarized, while highlighting the innovative and creative ways to overcome the limitations of LPMOs in hydrolyzing the biomass.
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Affiliation(s)
- Asheesh Kumar
- Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur, India
- Academy of Scientific and Innovative Research, Ghaziabad, India
| | - Aishwarya Singh
- Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur, India
| | - Vijay Kumar Sharma
- Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur, India
| | - Akshita Goel
- Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur, India
- Academy of Scientific and Innovative Research, Ghaziabad, India
| | - Arun Kumar
- Biotechnology Division, CSIR-Institute of Himalayan Bioresource Technology, Palampur, India
- Academy of Scientific and Innovative Research, Ghaziabad, India
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6
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Scott CJR, Leadbeater DR, Oates NC, James SR, Newling K, Li Y, McGregor NGS, Bird S, Bruce NC. Whole genome structural predictions reveal hidden diversity in putative oxidative enzymes of the lignocellulose-degrading ascomycete Parascedosporium putredinis NO1. Microbiol Spectr 2023; 11:e0103523. [PMID: 37811978 PMCID: PMC10714830 DOI: 10.1128/spectrum.01035-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Accepted: 08/22/2023] [Indexed: 10/10/2023] Open
Abstract
IMPORTANCE An annotated reference genome has revealed P. putredinis NO1 as a useful resource for the identification of new lignocellulose-degrading enzymes for biorefining of woody plant biomass. Utilizing a "structure-omics"-based searching strategy, we identified new potentially lignocellulose-active sequences that would have been missed by traditional sequence searching methods. These new identifications, alongside the discovery of novel enzymatic functions from this underexplored lineage with the recent discovery of a new phenol oxidase that cleaves the main structural β-O-4 linkage in lignin from P. putredinis NO1, highlight the underexplored and poorly represented family Microascaceae as a particularly interesting candidate worthy of further exploration toward the valorization of high value biorenewable products.
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Affiliation(s)
- Conor J. R. Scott
- Department of Biology, Centre for Novel Agricultural Products, University of York, York, United Kingdom
| | - Daniel R. Leadbeater
- Department of Biology, Centre for Novel Agricultural Products, University of York, York, United Kingdom
| | - Nicola C. Oates
- Department of Biology, Centre for Novel Agricultural Products, University of York, York, United Kingdom
| | - Sally R. James
- Department of Biology, Bioscience Technology Facility, University of York, York, United Kingdom
| | - Katherine Newling
- Department of Biology, Bioscience Technology Facility, University of York, York, United Kingdom
| | - Yi Li
- Department of Biology, Bioscience Technology Facility, University of York, York, United Kingdom
| | - Nicholas G. S. McGregor
- Department of Chemistry, York Structural Biology Laboratory, The University of York, York, United Kingdom
| | - Susannah Bird
- Department of Biology, Centre for Novel Agricultural Products, University of York, York, United Kingdom
| | - Neil C. Bruce
- Department of Biology, Centre for Novel Agricultural Products, University of York, York, United Kingdom
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7
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Østby H, Christensen IA, Hennum K, Várnai A, Buchinger E, Grandal S, Courtade G, Hegnar OA, Aachmann FL, Eijsink VGH. Functional characterization of a lytic polysaccharide monooxygenase from Schizophyllum commune that degrades non-crystalline substrates. Sci Rep 2023; 13:17373. [PMID: 37833388 PMCID: PMC10575960 DOI: 10.1038/s41598-023-44278-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Accepted: 10/05/2023] [Indexed: 10/15/2023] Open
Abstract
Lytic polysaccharide monooxygenases (LPMOs) are mono-copper enzymes that use O2 or H2O2 to oxidatively cleave glycosidic bonds. LPMOs are prevalent in nature, and the functional variation among these enzymes is a topic of great interest. We present the functional characterization of one of the 22 putative AA9-type LPMOs from the fungus Schizophyllum commune, ScLPMO9A. The enzyme, expressed in Escherichia coli, showed C4-oxidative cleavage of amorphous cellulose and soluble cello-oligosaccharides. Activity on xyloglucan, mixed-linkage β-glucan, and glucomannan was also observed, and product profiles differed compared to the well-studied C4-oxidizing NcLPMO9C from Neurospora crassa. While NcLPMO9C is also active on more crystalline forms of cellulose, ScLPMO9A is not. Differences between the two enzymes were also revealed by nuclear magnetic resonance (NMR) titration studies showing that, in contrast to NcLPMO9C, ScLPMO9A has higher affinity for linear substrates compared to branched substrates. Studies of H2O2-fueled degradation of amorphous cellulose showed that ScLPMO9A catalyzes a fast and specific peroxygenase reaction that is at least two orders of magnitude faster than the apparent monooxygenase reaction. Together, these results show that ScLPMO9A is an efficient LPMO with a broad substrate range, which, rather than acting on cellulose, has evolved to act on amorphous and soluble glucans.
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Affiliation(s)
- Heidi Østby
- Faculty of Chemistry, Biotechnology, and Food Science, Norwegian University of Life Sciences (NMBU), P.O. Box 5003, 1432, Ås, Norway
| | - Idd A Christensen
- Norwegian Biopolymer Laboratory (NOBIPOL), Department of Biotechnology and Food Science, NTNU Norwegian University of Science and Technology, Sem Sælands Vei 6/8, 7491, Trondheim, Norway
| | - Karen Hennum
- Faculty of Chemistry, Biotechnology, and Food Science, Norwegian University of Life Sciences (NMBU), P.O. Box 5003, 1432, Ås, Norway
| | - Anikó Várnai
- Faculty of Chemistry, Biotechnology, and Food Science, Norwegian University of Life Sciences (NMBU), P.O. Box 5003, 1432, Ås, Norway
| | - Edith Buchinger
- Norwegian Biopolymer Laboratory (NOBIPOL), Department of Biotechnology and Food Science, NTNU Norwegian University of Science and Technology, Sem Sælands Vei 6/8, 7491, Trondheim, Norway
| | - Siri Grandal
- Norwegian Biopolymer Laboratory (NOBIPOL), Department of Biotechnology and Food Science, NTNU Norwegian University of Science and Technology, Sem Sælands Vei 6/8, 7491, Trondheim, Norway
| | - Gaston Courtade
- Norwegian Biopolymer Laboratory (NOBIPOL), Department of Biotechnology and Food Science, NTNU Norwegian University of Science and Technology, Sem Sælands Vei 6/8, 7491, Trondheim, Norway
| | - Olav A Hegnar
- Faculty of Chemistry, Biotechnology, and Food Science, Norwegian University of Life Sciences (NMBU), P.O. Box 5003, 1432, Ås, Norway
| | - Finn L Aachmann
- Norwegian Biopolymer Laboratory (NOBIPOL), Department of Biotechnology and Food Science, NTNU Norwegian University of Science and Technology, Sem Sælands Vei 6/8, 7491, Trondheim, Norway
| | - Vincent G H Eijsink
- Faculty of Chemistry, Biotechnology, and Food Science, Norwegian University of Life Sciences (NMBU), P.O. Box 5003, 1432, Ås, Norway.
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8
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Grace Barrios-Gutiérrez S, Inés Vélez-Mercado M, Rodrigues Ortega J, da Silva Lima A, Luiza da Rocha Fortes Saraiva A, Leila Berto G, Segato F. Oxidative Machinery of basidiomycetes as potential enhancers in lignocellulosic biorefineries: A lytic polysaccharide monooxygenases approach. BIORESOURCE TECHNOLOGY 2023; 386:129481. [PMID: 37437815 DOI: 10.1016/j.biortech.2023.129481] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2023] [Revised: 07/05/2023] [Accepted: 07/08/2023] [Indexed: 07/14/2023]
Abstract
Basidiomycetes are renowned as highly effective decomposers of plant materials, due to their extensive array of oxidative enzymes, which enable them to efficiently break down complex lignocellulosic biomass structures. Among the oxidative machinery of industrially relevant basidiomycetes, the role of lytic polysaccharide monooxygenases (LPMO) in lignocellulosic biomass deconstruction is highlighted. So far, only a limited number of basidiomycetes LPMOs have been identified and heterologously expressed. These LPMOs have presented activity on cellulose and hemicellulose, as well as participation in the deconstruction of lignin. Expanding on this, the current review proposes both enzymatic and non-enzymatic mechanisms of LPMOs for biomass conversion, considering the significance of the Carbohydrate-Binding Modules and other C-terminal regions domains associated with their structure, which is involved in the deconstruction of lignocellulosic biomass.
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Affiliation(s)
- Solange Grace Barrios-Gutiérrez
- Synthetic and Molecular Biology Laboratory (SyMB), Department of Biotechnology, Lorena School of Engineering, University of São Paulo, Lorena, São Paulo, Brazil
| | - Martha Inés Vélez-Mercado
- Synthetic and Molecular Biology Laboratory (SyMB), Department of Biotechnology, Lorena School of Engineering, University of São Paulo, Lorena, São Paulo, Brazil
| | - Júlia Rodrigues Ortega
- Synthetic and Molecular Biology Laboratory (SyMB), Department of Biotechnology, Lorena School of Engineering, University of São Paulo, Lorena, São Paulo, Brazil
| | - Awana da Silva Lima
- Synthetic and Molecular Biology Laboratory (SyMB), Department of Biotechnology, Lorena School of Engineering, University of São Paulo, Lorena, São Paulo, Brazil
| | - Ana Luiza da Rocha Fortes Saraiva
- Synthetic and Molecular Biology Laboratory (SyMB), Department of Biotechnology, Lorena School of Engineering, University of São Paulo, Lorena, São Paulo, Brazil
| | - Gabriela Leila Berto
- Synthetic and Molecular Biology Laboratory (SyMB), Department of Biotechnology, Lorena School of Engineering, University of São Paulo, Lorena, São Paulo, Brazil
| | - Fernando Segato
- Synthetic and Molecular Biology Laboratory (SyMB), Department of Biotechnology, Lorena School of Engineering, University of São Paulo, Lorena, São Paulo, Brazil.
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9
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Dan M, Zheng Y, Zhao G, Hsieh YSY, Wang D. Current insights of factors interfering the stability of lytic polysaccharide monooxygenases. Biotechnol Adv 2023; 67:108216. [PMID: 37473820 DOI: 10.1016/j.biotechadv.2023.108216] [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: 03/20/2023] [Revised: 06/30/2023] [Accepted: 07/16/2023] [Indexed: 07/22/2023]
Abstract
Cellulose and chitin are two of the most abundant biopolymers in nature, but they cannot be effectively utilized in industry due to their recalcitrance. This limitation was overcome by the advent of lytic polysaccharide monooxygenases (LPMOs), which promote the disruption of biopolymers through oxidative mechanism and provide a breakthrough in the action of hydrolytic enzymes. In the application of LPMOs to biomass degradation, the key to consistent and effective functioning lies in their stability. The efficient transformation of biomass resources using LPMOs depends on factors that interfere with their stability. This review discussed three aspects that affect LPMO stability: general external factors, structural factors, and factors in the enzyme-substrate reaction. It explains how these factors impact LPMO stability, discusses the resulting effects, and finally presents relevant measures and considerations, including potential resolutions. The review also provides suggestions for the application of LPMOs in polysaccharide degradation.
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Affiliation(s)
- Meiling Dan
- College of Food Science, Southwest University, Chongqing 400715, China
| | - Yuting Zheng
- College of Food Science, Southwest University, Chongqing 400715, China
| | - Guohua Zhao
- College of Food Science, Southwest University, Chongqing 400715, China
| | - Yves S Y Hsieh
- Division of Glycoscience, Department of Chemistry, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, AlbaNova University Centre, 106 91 Stockholm, Sweden; School of Pharmacy, College of Pharmacy, Taipei Medical University, Taipei, Taiwan.
| | - Damao Wang
- College of Food Science, Southwest University, Chongqing 400715, China.
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10
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Zhao J, Zhuo Y, Diaz DE, Shanmugam M, Telfer AJ, Lindley PJ, Kracher D, Hayashi T, Seibt LS, Hardy FJ, Manners O, Hedison TM, Hollywood KA, Spiess R, Cain KM, Diaz-Moreno S, Scrutton NS, Tovborg M, Walton PH, Heyes DJ, Green AP. Mapping the Initial Stages of a Protective Pathway that Enhances Catalytic Turnover by a Lytic Polysaccharide Monooxygenase. J Am Chem Soc 2023; 145:20672-20682. [PMID: 37688545 PMCID: PMC10515631 DOI: 10.1021/jacs.3c06607] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Indexed: 09/11/2023]
Abstract
Oxygenase and peroxygenase enzymes generate intermediates at their active sites which bring about the controlled functionalization of inert C-H bonds in substrates, such as in the enzymatic conversion of methane to methanol. To be viable catalysts, however, these enzymes must also prevent oxidative damage to essential active site residues, which can occur during both coupled and uncoupled turnover. Herein, we use a combination of stopped-flow spectroscopy, targeted mutagenesis, TD-DFT calculations, high-energy resolution fluorescence detection X-ray absorption spectroscopy, and electron paramagnetic resonance spectroscopy to study two transient intermediates that together form a protective pathway built into the active sites of copper-dependent lytic polysaccharide monooxygenases (LPMOs). First, a transient high-valent species is generated at the copper histidine brace active site following treatment of the LPMO with either hydrogen peroxide or peroxyacids in the absence of substrate. This intermediate, which we propose to be a CuII-(histidyl radical), then reacts with a nearby tyrosine residue in an intersystem-crossing reaction to give a ferromagnetically coupled (S = 1) CuII-tyrosyl radical pair, thereby restoring the histidine brace active site to its resting state and allowing it to re-enter the catalytic cycle through reduction. This process gives the enzyme the capacity to minimize damage to the active site histidine residues "on the fly" to increase the total turnover number prior to enzyme deactivation, highlighting how oxidative enzymes are evolved to protect themselves from deleterious side reactions during uncoupled turnover.
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Affiliation(s)
- Jingming Zhao
- Manchester
Institute of Biotechnology, The University
of Manchester, 131 Princess Street, Manchester M1 7DN, U.K.
| | - Ying Zhuo
- Manchester
Institute of Biotechnology, The University
of Manchester, 131 Princess Street, Manchester M1 7DN, U.K.
| | - Daniel E. Diaz
- Department
of Chemistry, University of York, Heslington, York YO10 5DD, U.K.
| | - Muralidharan Shanmugam
- Manchester
Institute of Biotechnology, The University
of Manchester, 131 Princess Street, Manchester M1 7DN, U.K.
| | - Abbey J. Telfer
- Department
of Chemistry, University of York, Heslington, York YO10 5DD, U.K.
- Harwell
Science and Innovation Campus, Diamond Light
Source Ltd., Didcot, Oxfordshire OX11 0DE, U.K.
| | - Peter J. Lindley
- Department
of Chemistry, University of York, Heslington, York YO10 5DD, U.K.
| | - Daniel Kracher
- Institute
of Molecular Biotechnology, Graz University
of Technology, Petersgasse
14, Graz 8010, Austria
| | - Takahiro Hayashi
- Manchester
Institute of Biotechnology, The University
of Manchester, 131 Princess Street, Manchester M1 7DN, U.K.
| | - Lisa S. Seibt
- Manchester
Institute of Biotechnology, The University
of Manchester, 131 Princess Street, Manchester M1 7DN, U.K.
| | - Florence J. Hardy
- Manchester
Institute of Biotechnology, The University
of Manchester, 131 Princess Street, Manchester M1 7DN, U.K.
| | - Oliver Manners
- Manchester
Institute of Biotechnology, The University
of Manchester, 131 Princess Street, Manchester M1 7DN, U.K.
| | - Tobias M. Hedison
- Manchester
Institute of Biotechnology, The University
of Manchester, 131 Princess Street, Manchester M1 7DN, U.K.
| | - Katherine A. Hollywood
- Manchester
Institute of Biotechnology, The University
of Manchester, 131 Princess Street, Manchester M1 7DN, U.K.
| | - Reynard Spiess
- Manchester
Institute of Biotechnology, The University
of Manchester, 131 Princess Street, Manchester M1 7DN, U.K.
| | - Kathleen M. Cain
- Manchester
Institute of Biotechnology, The University
of Manchester, 131 Princess Street, Manchester M1 7DN, U.K.
| | - Sofia Diaz-Moreno
- Harwell
Science and Innovation Campus, Diamond Light
Source Ltd., Didcot, Oxfordshire OX11 0DE, U.K.
| | - Nigel S. Scrutton
- Manchester
Institute of Biotechnology, The University
of Manchester, 131 Princess Street, Manchester M1 7DN, U.K.
| | | | - Paul H. Walton
- Department
of Chemistry, University of York, Heslington, York YO10 5DD, U.K.
| | - Derren J. Heyes
- Manchester
Institute of Biotechnology, The University
of Manchester, 131 Princess Street, Manchester M1 7DN, U.K.
| | - Anthony P. Green
- Manchester
Institute of Biotechnology, The University
of Manchester, 131 Princess Street, Manchester M1 7DN, U.K.
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11
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Kuusk S, Eijsink VGH, Väljamäe P. The "life-span" of lytic polysaccharide monooxygenases (LPMOs) correlates to the number of turnovers in the reductant peroxidase reaction. J Biol Chem 2023; 299:105094. [PMID: 37507015 PMCID: PMC10458328 DOI: 10.1016/j.jbc.2023.105094] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Revised: 07/02/2023] [Accepted: 07/22/2023] [Indexed: 07/30/2023] Open
Abstract
Lytic polysaccharide monooxygenases (LPMOs) are monocopper enzymes that degrade the insoluble crystalline polysaccharides cellulose and chitin. Besides the H2O2 cosubstrate, the cleavage of glycosidic bonds by LPMOs depends on the presence of a reductant needed to bring the enzyme into its reduced, catalytically active Cu(I) state. Reduced LPMOs that are not bound to substrate catalyze reductant peroxidase reactions, which may lead to oxidative damage and irreversible inactivation of the enzyme. However, the kinetics of this reaction remain largely unknown, as do possible variations between LPMOs belonging to different families. Here, we describe the kinetic characterization of two fungal family AA9 LPMOs, TrAA9A of Trichoderma reesei and NcAA9C of Neurospora crassa, and two bacterial AA10 LPMOs, ScAA10C of Streptomyces coelicolor and SmAA10A of Serratia marcescens. We found peroxidation of ascorbic acid and methyl-hydroquinone resulted in the same probability of LPMO inactivation (pi), suggesting that inactivation is independent of the nature of the reductant. We showed the fungal enzymes were clearly more resistant toward inactivation, having pi values of less than 0.01, whereas the pi for SmAA10A was an order of magnitude higher. However, the fungal enzymes also showed higher catalytic efficiencies (kcat/KM(H2O2)) for the reductant peroxidase reaction. This inverse linear correlation between the kcat/KM(H2O2) and pi suggests that, although having different life spans in terms of the number of turnovers in the reductant peroxidase reaction, LPMOs that are not bound to substrates have similar half-lives. These findings have not only potential biological but also industrial implications.
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Affiliation(s)
- Silja Kuusk
- Institute of Molecular and Cell Biology, University of Tartu, Tartu, Estonia
| | - Vincent G H Eijsink
- Faculty of Chemistry, Biotechnology and Food Science, NMBU - Norwegian University of Life Sciences, Ås, Norway
| | - Priit Väljamäe
- Institute of Molecular and Cell Biology, University of Tartu, Tartu, Estonia.
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12
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Batth TS, Simonsen JL, Hernández-Rollán C, Brander S, Morth JP, Johansen KS, Nørholm MHH, Hoof JB, Olsen JV. A seven-transmembrane methyltransferase catalysing N-terminal histidine methylation of lytic polysaccharide monooxygenases. Nat Commun 2023; 14:4202. [PMID: 37452022 PMCID: PMC10349129 DOI: 10.1038/s41467-023-39875-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Accepted: 06/29/2023] [Indexed: 07/18/2023] Open
Abstract
Lytic polysaccharide monooxygenases (LPMOs) are oxidative enzymes that help break down lignocellulose, making them highly attractive for improving biomass utilization in industrial biotechnology. The catalytically essential N-terminal histidine (His1) of LPMOs is post-translationally modified by methylation in filamentous fungi to protect them from auto-oxidative inactivation, however, the responsible methyltransferase enzyme is unknown. Using mass-spectrometry-based quantitative proteomics in combination with systematic CRISPR/Cas9 knockout screening in Aspergillus nidulans, we identify the N-terminal histidine methyltransferase (NHMT) encoded by the gene AN4663. Targeted proteomics confirm that NHMT was solely responsible for His1 methylation of LPMOs. NHMT is predicted to encode a unique seven-transmembrane segment anchoring a soluble methyltransferase domain. Co-localization studies show endoplasmic reticulum residence of NHMT and co-expression in the industrial production yeast Komagataella phaffii with LPMOs results in His1 methylation of the LPMOs. This demonstrates the biotechnological potential of recombinant production of proteins and peptides harbouring this specific post-translational modification.
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Affiliation(s)
- Tanveer S Batth
- The Novo Nordisk Foundation Center for Protein Research, University of Copenhagen Denmark, Copenhagen, Denmark.
| | - Jonas L Simonsen
- The Novo Nordisk Foundation Center for Protein Research, University of Copenhagen Denmark, Copenhagen, Denmark
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Cristina Hernández-Rollán
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Søren Brander
- Department of Geosciences and Natural Resource Management, University of Copenhagen, Frederiksberg, Denmark
| | - Jens Preben Morth
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Kongens Lyngby, Denmark
| | - Katja S Johansen
- Department of Geosciences and Natural Resource Management, University of Copenhagen, Frederiksberg, Denmark
| | - Morten H H Nørholm
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kongens Lyngby, Denmark.
| | - Jakob B Hoof
- Department of Biotechnology and Biomedicine, Technical University of Denmark, Kongens Lyngby, Denmark.
| | - Jesper V Olsen
- The Novo Nordisk Foundation Center for Protein Research, University of Copenhagen Denmark, Copenhagen, Denmark.
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13
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Caputo F, Tõlgo M, Naidjonoka P, Krogh KBRM, Novy V, Olsson L. Investigating the role of AA9 LPMOs in enzymatic hydrolysis of differentially steam-pretreated spruce. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2023; 16:68. [PMID: 37076886 PMCID: PMC10114483 DOI: 10.1186/s13068-023-02316-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2023] [Accepted: 03/31/2023] [Indexed: 04/21/2023]
Abstract
BACKGROUND To realize the full potential of softwood-based forest biorefineries, the bottlenecks of enzymatic saccharification of softwood need to be better understood. Here, we investigated the potential of lytic polysaccharide monooxygenases (LPMO9s) in softwood saccharification. Norway spruce was steam-pretreated at three different severities, leading to varying hemicellulose retention, lignin condensation, and cellulose ultrastructure. Hydrolyzability of the three substrates was assessed after pretreatment and after an additional knife-milling step, comparing the efficiency of cellulolytic Celluclast + Novozym 188 and LPMO-containing Cellic CTec2 cocktails. The role of Thermoascus aurantiacus TaLPMO9 in saccharification was assessed through time-course analysis of sugar release and accumulation of oxidized sugars, as well as wide-angle X-ray scattering analysis of cellulose ultrastructural changes. RESULTS Glucose yield was 6% (w/w) with the mildest pretreatment (steam pretreatment at 210 °C without catalyst) and 66% (w/w) with the harshest (steam pretreatment at 210 °C with 3%(w/w) SO2) when using Celluclast + Novozym 188. Surprisingly, the yield was lower with all substrates when Cellic CTec2 was used. Therefore, the conditions for optimal LPMO activity were tested and it was found that enough O2 was present over the headspace and that the reducing power of the lignin of all three substrates was sufficient for the LPMOs in Cellic CTec2 to be active. Supplementation of Celluclast + Novozym 188 with TaLPMO9 increased the conversion of glucan by 1.6-fold and xylan by 1.5-fold, which was evident primarily in the later stages of saccharification (24-72 h). Improved glucan conversion could be explained by drastically reduced cellulose crystallinity of spruce substrates upon TaLPMO9 supplementation. CONCLUSION Our study demonstrated that LPMO addition to hydrolytic enzymes improves the release of glucose and xylose from steam-pretreated softwood substrates. Furthermore, softwood lignin provides enough reducing power for LPMOs, irrespective of pretreatment severity. These results provided new insights into the potential role of LPMOs in saccharification of industrially relevant softwood substrates.
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Affiliation(s)
- Fabio Caputo
- Division of Industrial Biotechnology, Department of Biology and Biological Engineering, Chalmers University of Technology, Kemivägen 10, 412 96, Gothenburg, Sweden
| | - Monika Tõlgo
- Division of Industrial Biotechnology, Department of Biology and Biological Engineering, Chalmers University of Technology, Kemivägen 10, 412 96, Gothenburg, Sweden
- Wallenberg Wood Science Center, Chalmers University of Technology, Kemigården 4, 412 96, Gothenburg, Sweden
| | - Polina Naidjonoka
- Wallenberg Wood Science Center, Chalmers University of Technology, Kemigården 4, 412 96, Gothenburg, Sweden
- Division of Materials Physics, Department of Physics, Chalmers University of Technology, Kemigården 1, 412 96, Gothenburg, Sweden
| | | | - Vera Novy
- Division of Industrial Biotechnology, Department of Biology and Biological Engineering, Chalmers University of Technology, Kemivägen 10, 412 96, Gothenburg, Sweden
- Wallenberg Wood Science Center, Chalmers University of Technology, Kemigården 4, 412 96, Gothenburg, Sweden
| | - Lisbeth Olsson
- Division of Industrial Biotechnology, Department of Biology and Biological Engineering, Chalmers University of Technology, Kemivägen 10, 412 96, Gothenburg, Sweden.
- Wallenberg Wood Science Center, Chalmers University of Technology, Kemigården 4, 412 96, Gothenburg, Sweden.
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14
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Østby H, Várnai A. Hemicellulolytic enzymes in lignocellulose processing. Essays Biochem 2023; 67:533-550. [PMID: 37068264 PMCID: PMC10160854 DOI: 10.1042/ebc20220154] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 01/25/2023] [Accepted: 01/30/2023] [Indexed: 04/19/2023]
Abstract
Lignocellulosic biomass is the most abundant source of carbon-based material on a global basis, serving as a raw material for cellulosic fibers, hemicellulosic polymers, platform sugars, and lignin resins or monomers. In nature, the various components of lignocellulose (primarily cellulose, hemicellulose, and lignin) are decomposed by saprophytic fungi and bacteria utilizing specialized enzymes. Enzymes are specific catalysts and can, in many cases, be produced on-site at lignocellulose biorefineries. In addition to reducing the use of often less environmentally friendly chemical processes, the application of such enzymes in lignocellulose processing to obtain a range of specialty products can maximize the use of the feedstock and valorize many of the traditionally underutilized components of lignocellulose, while increasing the economic viability of the biorefinery. While cellulose has a rich history of use in the pulp and paper industries, the hemicellulosic fraction of lignocellulose remains relatively underutilized in modern biorefineries, among other reasons due to the heterogeneous chemical structure of hemicellulose polysaccharides, the composition of which varies significantly according to the feedstock and the choice of pretreatment method and extraction solvent. This paper reviews the potential of hemicellulose in lignocellulose processing with focus on what can be achieved using enzymatic means. In particular, we discuss the various enzyme activities required for complete depolymerization of the primary hemicellulose types found in plant cell walls and for the upgrading of hemicellulosic polymers, oligosaccharides, and pentose sugars derived from hemicellulose depolymerization into a broad spectrum of value-added products.
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Affiliation(s)
- Heidi Østby
- Norwegian University of Life Sciences (NMBU), Faculty of Chemistry, Biotechnology and Food Science, P.O. Box 5003, N-1432 Aas, Norway
| | - Anikó Várnai
- Norwegian University of Life Sciences (NMBU), Faculty of Chemistry, Biotechnology and Food Science, P.O. Box 5003, N-1432 Aas, Norway
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15
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Sun P, Huang Z, Banerjee S, Kadowaki MAS, Veersma RJ, Magri S, Hilgers R, Muderspach SJ, Laurent CV, Ludwig R, Cannella D, Lo Leggio L, van Berkel WJH, Kabel MA. AA16 Oxidoreductases Boost Cellulose-Active AA9 Lytic Polysaccharide Monooxygenases from Myceliophthora thermophila. ACS Catal 2023; 13:4454-4467. [PMID: 37066045 PMCID: PMC10088020 DOI: 10.1021/acscatal.3c00874] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 03/06/2023] [Indexed: 04/18/2023]
Abstract
Copper-dependent lytic polysaccharide monooxygenases (LPMOs) classified in Auxiliary Activity (AA) families are considered indispensable as synergistic partners for cellulolytic enzymes to saccharify recalcitrant lignocellulosic plant biomass. In this study, we characterized two fungal oxidoreductases from the new AA16 family. We found that MtAA16A from Myceliophthora thermophila and AnAA16A from Aspergillus nidulans did not catalyze the oxidative cleavage of oligo- and polysaccharides. Indeed, the MtAA16A crystal structure showed a fairly LPMO-typical histidine brace active site, but the cellulose-acting LPMO-typical flat aromatic surface parallel to the histidine brace region was lacking. Further, we showed that both AA16 proteins are able to oxidize low-molecular-weight reductants to produce H2O2. The oxidase activity of the AA16s substantially boosted cellulose degradation by four AA9 LPMOs from M. thermophila (MtLPMO9s) but not by three AA9 LPMOs from Neurospora crassa (NcLPMO9s). The interplay with MtLPMO9s is explained by the H2O2-producing capability of the AA16s, which, in the presence of cellulose, allows the MtLPMO9s to optimally drive their peroxygenase activity. Replacement of MtAA16A by glucose oxidase (AnGOX) with the same H2O2-producing activity could only achieve less than 50% of the boosting effect achieved by MtAA16A, and earlier MtLPMO9B inactivation (6 h) was observed. To explain these results, we hypothesized that the delivery of AA16-produced H2O2 to the MtLPMO9s is facilitated by protein-protein interaction. Our findings provide new insights into the functions of copper-dependent enzymes and contribute to a further understanding of the interplay of oxidative enzymes within fungal systems to degrade lignocellulose.
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Affiliation(s)
- Peicheng Sun
- Laboratory
of Food Chemistry, Wageningen University
& Research, Bornse Weilanden 9, 6708 WG Wageningen, The Netherlands
| | - Zhiyu Huang
- Department
of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| | - Sanchari Banerjee
- Department
of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| | - Marco A. S. Kadowaki
- PhotoBioCatalysis
Unit (CPBL) and Biomass Transformation Lab (BTL), École Interfacultaire
de Bioingénieurs (EIB), Université
Libre de Bruxelles, Avenue Franklin D. Roosevelt 50, 1050 Bruxelles, Belgium
| | - Romy J. Veersma
- Laboratory
of Food Chemistry, Wageningen University
& Research, Bornse Weilanden 9, 6708 WG Wageningen, The Netherlands
| | - Silvia Magri
- PhotoBioCatalysis
Unit (CPBL) and Biomass Transformation Lab (BTL), École Interfacultaire
de Bioingénieurs (EIB), Université
Libre de Bruxelles, Avenue Franklin D. Roosevelt 50, 1050 Bruxelles, Belgium
| | - Roelant Hilgers
- Laboratory
of Food Chemistry, Wageningen University
& Research, Bornse Weilanden 9, 6708 WG Wageningen, The Netherlands
| | - Sebastian J. Muderspach
- Department
of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| | - Christophe V.F.P. Laurent
- Biocatalysis
and Biosensing Laboratory, Department of Food Science and Technology, University of Natural Resources and Life Sciences
(BOKU), Muthgasse 18, 1190 Vienna, Austria
- Institute
of Molecular Modeling and Simulation, Department of Material Sciences
and Process Engineering, University of Natural
Resources and Life Sciences (BOKU), Muthgasse 18, 1190 Vienna, Austria
| | - Roland Ludwig
- Biocatalysis
and Biosensing Laboratory, Department of Food Science and Technology, University of Natural Resources and Life Sciences
(BOKU), Muthgasse 18, 1190 Vienna, Austria
| | - David Cannella
- PhotoBioCatalysis
Unit (CPBL) and Biomass Transformation Lab (BTL), École Interfacultaire
de Bioingénieurs (EIB), Université
Libre de Bruxelles, Avenue Franklin D. Roosevelt 50, 1050 Bruxelles, Belgium
| | - Leila Lo Leggio
- Department
of Chemistry, University of Copenhagen, Universitetsparken 5, 2100 Copenhagen, Denmark
| | - Willem J. H. van Berkel
- Laboratory
of Food Chemistry, Wageningen University
& Research, Bornse Weilanden 9, 6708 WG Wageningen, The Netherlands
| | - Mirjam A. Kabel
- Laboratory
of Food Chemistry, Wageningen University
& Research, Bornse Weilanden 9, 6708 WG Wageningen, The Netherlands
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16
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Torbjörnsson M, Hagemann MM, Ryde U, Hedegård ED. Histidine oxidation in lytic polysaccharide monooxygenase. J Biol Inorg Chem 2023; 28:317-328. [PMID: 36828975 PMCID: PMC10036459 DOI: 10.1007/s00775-023-01993-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Accepted: 01/10/2023] [Indexed: 02/26/2023]
Abstract
The lytic polysaccharide monooxygenases (LPMOs) comprise a super-family of copper enzymes that boost the depolymerisation of polysaccharides by oxidatively disrupting the glycosidic bonds connecting the sugar units. Industrial use of LPMOs for cellulose depolymerisation has already begun but is still far from reaching its full potential. One issue is that the LPMOs self-oxidise and thereby deactivate. The mechanism of this self-oxidation is unknown, but histidine residues coordinating to the copper atom are the most susceptible. An unusual methyl modification of the NE2 atom in one of the coordinating histidine residues has been proposed to have a protective role. Furthermore, substrate binding is also known to reduce oxidative damage. We here for the first time investigate the mechanism of histidine oxidation with combined quantum and molecular mechanical (QM/MM) calculations, with outset in intermediates previously shown to form from a reaction with peroxide and a reduced LPMO. We show that an intermediate with a [Cu-O]+ moiety is sufficiently potent to oxidise the nearest C-H bond on both histidine residues, but methylation of the NE2 atom of His-1 increases the reaction barrier of this reaction. The substrate further increases the activation barrier. We also investigate a [Cu-OH]2+ intermediate with a deprotonated tyrosine radical. This intermediate was previously proposed to have a protective role, and we also find it to have higher barriers than the corresponding a [Cu-O]+ intermediate.
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Affiliation(s)
- Magne Torbjörnsson
- Department of Theoretical Chemistry, Lund University, Chemical Centre, P. O. Box 124, 221 00, Lund, Sweden
| | - Marlisa M Hagemann
- Department of Physics, Chemistry, and Pharmacy, University of Southern Denmark, Campusvej 55, 5230, Odense M, Denmark
| | - Ulf Ryde
- Department of Theoretical Chemistry, Lund University, Chemical Centre, P. O. Box 124, 221 00, Lund, Sweden.
| | - Erik Donovan Hedegård
- Department of Theoretical Chemistry, Lund University, Chemical Centre, P. O. Box 124, 221 00, Lund, Sweden.
- Department of Physics, Chemistry, and Pharmacy, University of Southern Denmark, Campusvej 55, 5230, Odense M, Denmark.
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17
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Ipsen JØ, Johansen KS, Brander S. A fast, sensitive and fluorescent LPMO activity assay. Front Microbiol 2023; 14:1128470. [PMID: 36998406 PMCID: PMC10043361 DOI: 10.3389/fmicb.2023.1128470] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Accepted: 02/21/2023] [Indexed: 03/16/2023] Open
Abstract
Lytic polysaccharide monooxygenases (LPMOs) are industrially relevant enzymes that utilize a copper co-factor and an oxygen species to break down recalcitrant polysaccharides. These enzymes are secreted by microorganisms and are used in lignocellulosic refineries. As such, they are interesting from both the ecological/biological and industrial perspectives. Here we describe the development of a new fluorescence-based kinetic LPMO activity assay. The assay is based on the enzymatic production of fluorescein from its reduced counterpart. The assay can detect as little as 1 nM LPMO with optimized assay conditions. Furthermore, the reduced fluorescein substrate can also be used to identify peroxidase activity as seen by the formation of fluorescein by horseradish peroxidase. The assay was shown to work well at relatively low H2O2 and dehydroascorbate concentrations. The applicability of the assay was demonstrated.
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18
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The interplay between lytic polysaccharide monooxygenases and glycoside hydrolases. Essays Biochem 2023; 67:551-559. [PMID: 36876880 DOI: 10.1042/ebc20220156] [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: 10/20/2022] [Revised: 12/23/2022] [Accepted: 01/03/2023] [Indexed: 03/07/2023]
Abstract
In nature, enzymatic degradation of recalcitrant polysaccharides such as chitin and cellulose takes place by a synergistic interaction between glycoside hydrolases (GHs) and lytic polysaccharide monooxygenases (LPMOs). The two different families of carbohydrate-active enzymes use two different mechanisms when breaking glycosidic bonds between sugar moieties. GHs employ a hydrolytic activity and LPMOs are oxidative. Consequently, the topologies of the active sites differ dramatically. GHs have tunnels or clefts lined with a sheet of aromatic amino acid residues accommodating single polymer chains being threaded into the active site. LPMOs are adapted to bind to the flat crystalline surfaces of chitin and cellulose. It is believed that the LPMO oxidative mechanism provides new chain ends that the GHs can attach to and degrade, often in a processive manner. Indeed, there are many reports of synergies as well as rate enhancements when LPMOs are applied in concert with GHs. Still, these enhancements vary in magnitude with respect to the nature of the GH and the LPMO. Moreover, impediment of GH catalysis is also observed. In the present review, we discuss central works where the interplay between LPMOs and GHs has been studied and comment on future challenges to be addressed to fully use the potential of this interplay to improve enzymatic polysaccharide degradation.
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19
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Kommedal EG, Angeltveit CF, Klau LJ, Ayuso-Fernández I, Arstad B, Antonsen SG, Stenstrøm Y, Ekeberg D, Gírio F, Carvalheiro F, Horn SJ, Aachmann FL, Eijsink VGH. Visible light-exposed lignin facilitates cellulose solubilization by lytic polysaccharide monooxygenases. Nat Commun 2023; 14:1063. [PMID: 36828821 PMCID: PMC9958194 DOI: 10.1038/s41467-023-36660-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Accepted: 02/10/2023] [Indexed: 02/26/2023] Open
Abstract
Lytic polysaccharide monooxygenases (LPMOs) catalyze oxidative cleavage of crystalline polysaccharides such as cellulose and are crucial for the conversion of plant biomass in Nature and in industrial applications. Sunlight promotes microbial conversion of plant litter; this effect has been attributed to photochemical degradation of lignin, a major redox-active component of secondary plant cell walls that limits enzyme access to the cell wall carbohydrates. Here, we show that exposing lignin to visible light facilitates cellulose solubilization by promoting formation of H2O2 that fuels LPMO catalysis. Light-driven H2O2 formation is accompanied by oxidation of ring-conjugated olefins in the lignin, while LPMO-catalyzed oxidation of phenolic hydroxyls leads to the required priming reduction of the enzyme. The discovery that light-driven abiotic reactions in Nature can fuel H2O2-dependent redox enzymes involved in deconstructing lignocellulose may offer opportunities for bioprocessing and provides an enzymatic explanation for the known effect of visible light on biomass conversion.
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Affiliation(s)
- Eirik G Kommedal
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), 1432, Ås, Norway
| | - Camilla F Angeltveit
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), 1432, Ås, Norway
| | - Leesa J Klau
- Department of Biotechnology and Food Science, Norwegian University of Science and Technology (NTNU), 7491, Trondheim, Norway
| | - Iván Ayuso-Fernández
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), 1432, Ås, Norway
| | - Bjørnar Arstad
- SINTEF Industry, Process Chemistry and Functional Materials, 0373, Oslo, Norway
| | - Simen G Antonsen
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), 1432, Ås, Norway
| | - Yngve Stenstrøm
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), 1432, Ås, Norway
| | - Dag Ekeberg
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), 1432, Ås, Norway
| | - Francisco Gírio
- National Laboratory of Energy and Geology (LNEG), 1649-038, Lisboa, Portugal
| | | | - Svein J Horn
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), 1432, Ås, Norway
| | - Finn Lillelund Aachmann
- Department of Biotechnology and Food Science, Norwegian University of Science and Technology (NTNU), 7491, Trondheim, Norway
| | - Vincent G H Eijsink
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), 1432, Ås, Norway.
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20
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Hagemann MM, Hedegård ED. Molecular Mechanism of Substrate Oxidation in Lytic Polysaccharide Monooxygenases: Insight from Theoretical Investigations. Chemistry 2023; 29:e202202379. [PMID: 36207279 PMCID: PMC10107554 DOI: 10.1002/chem.202202379] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2022] [Indexed: 12/12/2022]
Abstract
Lytic polysaccharide monooxygenases (LPMOs) are copper enzymes that today comprise a large enzyme superfamily, grouped into the distinct members AA9-AA17 (with AA12 exempted). The LPMOs have the potential to facilitate the upcycling of biomass waste products by boosting the breakdown of cellulose and other recalcitrant polysaccharides. The cellulose biopolymer is the main component of biomass waste and thus comprises a large, unexploited resource. The LPMOs work through a catalytic, oxidative reaction whose mechanism is still controversial. For instance, the nature of the intermediate performing the oxidative reaction is an open question, and the same holds for the employed co-substrate. Here we review theoretical investigations addressing these questions. The applied theoretical methods are usually based on quantum mechanics (QM), often combined with molecular mechanics (QM/MM). We discuss advantages and disadvantages of the employed theoretical methods and comment on the interplay between theoretical and experimental results.
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Affiliation(s)
- Marlisa M Hagemann
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, 5230, Odense, Denmark
| | - Erik D Hedegård
- Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, Campusvej 55, 5230, Odense, Denmark
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21
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Walton PH, Davies GJ, Diaz DE, Franco‐Cairo JP. The histidine brace: nature's copper alternative to haem? FEBS Lett 2023; 597:485-494. [PMID: 36660911 PMCID: PMC10952591 DOI: 10.1002/1873-3468.14579] [Citation(s) in RCA: 10] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2022] [Revised: 01/06/2023] [Accepted: 01/07/2023] [Indexed: 01/21/2023]
Abstract
The copper histidine brace is a structural unit in metalloproteins (Proc Natl Acad Sci USA 2011, 108, 15079). It consists of a copper ion chelated by the NH2 and π-N atom of an N-terminal histidine, and the τ-N atom of a further histidine, in an overall T-shaped coordination geometry (Nat Catal 2018, 1, 571). Like haem-containing proteins, histidine-brace-containing proteins have peroxygenase and/or oxygenase activity, where the substrates are notable for resistance to oxidation, for example, lytic polysaccharide monooxygenases (LPMOs). Moreover, the histidine brace is an invariant unit around which different protein structures exert different activities. Given the similarities in the diversity of function of proteins that contain either the copper histidine brace or haem, the question arises as to whether the functions of histidine brace-containing proteins duplicate those containing haem groups.
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22
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Harvey DJ. Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update for 2017-2018. MASS SPECTROMETRY REVIEWS 2023; 42:227-431. [PMID: 34719822 DOI: 10.1002/mas.21721] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Revised: 07/26/2021] [Accepted: 07/26/2021] [Indexed: 06/13/2023]
Abstract
This review is the tenth update of the original article published in 1999 on the application of matrix-assisted laser desorption/ionization mass spectrometry (MALDI) mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2018. Also included are papers that describe methods appropriate to glycan and glycoprotein analysis by MALDI, such as sample preparation techniques, even though the ionization method is not MALDI. Topics covered in the first part of the review include general aspects such as theory of the MALDI process, new methods, matrices, derivatization, MALDI imaging, fragmentation and the use of arrays. The second part of the review is devoted to applications to various structural types such as oligo- and poly-saccharides, glycoproteins, glycolipids, glycosides, and biopharmaceuticals. Most of the applications are presented in tabular form. The third part of the review covers medical and industrial applications of the technique, studies of enzyme reactions, and applications to chemical synthesis. The reported work shows increasing use of combined new techniques such as ion mobility and highlights the impact that MALDI imaging is having across a range of diciplines. MALDI is still an ideal technique for carbohydrate analysis and advancements in the technique and the range of applications continue steady progress.
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Affiliation(s)
- David J Harvey
- Nuffield Department of Medicine, Target Discovery Institute, University of Oxford, Oxford, UK
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Abstract
Lytic polysaccharide monooxygenases (LPMOs) are unique redox enzymes capable of disrupting the crystalline surfaces of industry-relevant recalcitrant polysaccharides, such as chitin and cellulose. Historically, LPMOs were thought to be slow enzymes relying on O2 as the co-substrate, but it is now clear that these enzymes prefer H2O2, allowing for fast depolymerization of polysaccharides through a peroxygenase reaction. Thus, quantifying H2O2 in LPMO reaction set-ups is of a great interest. The horseradish peroxidase (HRP)/Amplex Red (AR) assay is one of the most popular and accessible tools for measuring hydrogen peroxide. This assay has been used in various types of biological and biochemical studies, including LPMO research, but suffers from pitfalls that need to be accounted for. In this Chapter, we discuss this method and its use for assessing the often rate-limiting in situ formation of H2O2 in LPMO reactions. We show that, after accounting for multiple potential side reactions, quantitative data on H2O2 production obtained with the HRP/Amplex Red assay provide useful clues for understanding the catalytic activity of LPMOs, including the impact of reductants and transition metal ions.
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Affiliation(s)
- Anton A Stepnov
- Faculty of Chemistry, Biotechnology and Food Science, NMBU-Norwegian University of Life Sciences, Ås, Norway
| | - Vincent G H Eijsink
- Faculty of Chemistry, Biotechnology and Food Science, NMBU-Norwegian University of Life Sciences, Ås, Norway.
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Yu W, Yu J, Li D. Analysis of lytic polysaccharide monooxygenase activity in thermophilic fungi by high-performance liquid chromatography–refractive index detector. Front Microbiol 2022; 13:1063025. [DOI: 10.3389/fmicb.2022.1063025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Accepted: 11/07/2022] [Indexed: 11/23/2022] Open
Abstract
IntroductionMost current methods for analysing the activity of LPMO are based on the quantification of H2O2, a side product of LPMO; however, these methods cannot assay the LPMO activity of thermophilic fungi because of the low thermostability of H2O2. Therefore, we present a high-performance liquid chromatography–refractive index detector (HPLC-RID) method to assay the LPMO activity of the thermophilic fungus Thermoascus aurantiacus.ResultsAccording to the established method, the specific activities of nTaAA9A C1 and C4 oxidation were successfully analysed and were 0.646 and 0.574 U/mg, respectively. By using these methods, we analyzed the C1 and C4 oxidation activities of the recombinant TaAA9A (rTaAA9A) and mutated rTaAA9A (Y24A, F43A, and Y212A) expressed in Pichia pastoris. The specific activities of rTaAA9A C1 and C4 oxidation were 0.155 and 0.153 U/mg, respectively. The specific activities of Y24A, F43A, and Y212A C1 and C4 oxidation were 0.128 and 0.125 U/mg, 0.194 and 0.192 U/mg, and 0.097 and 0.146 U/mg, respectively.DiscussionIn conclusion, the method can assay the LPMO activity of thermophilic fungi and directly target C1 and C4 oxidation, which provides an effective activity assay method for LPMOs of thermophilic fungi.
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25
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Lee J, Yang M, Song WJ. The expanded landscape of metalloproteins by genetic incorporation of noncanonical amino acids. B KOREAN CHEM SOC 2022. [DOI: 10.1002/bkcs.12635] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Jaehee Lee
- Department of Chemistry Seoul National University Seoul South Korea
| | - Minwoo Yang
- Department of Chemistry Seoul National University Seoul South Korea
| | - Woon Ju Song
- Department of Chemistry Seoul National University Seoul South Korea
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26
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Guo X, An Y, Liu F, Lu F, Wang B. Lytic polysaccharide monooxygenase - A new driving force for lignocellulosic biomass degradation. BIORESOURCE TECHNOLOGY 2022; 362:127803. [PMID: 35995343 DOI: 10.1016/j.biortech.2022.127803] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2022] [Revised: 08/15/2022] [Accepted: 08/16/2022] [Indexed: 06/15/2023]
Abstract
Lytic polysaccharide monooxygenases (LPMOs) can catalyze polysaccharides by oxidative cleavage of glycosidic bonds and have catalytic activity for cellulose, hemicellulose, chitin, starch and pectin, thus playing an important role in the biomass conversion of lignocellulose. The catalytic substrates of LPMOs are different and the specific catalytic mechanism has not been fully elucidated. Although there have been many studies related to LPMOs, few have actually been put into industrial biomass conversion, which poses a challenge for their expression, regulation and application. In this review, the origin, substrate specificity, structural features, and the relationship between structure and function of LPMOs are described. Additionally, the catalytic mechanism and electron donor of LPMOs and their heterologous expression and regulation are discussed. Finally, the synergistic degradation of biomass by LPMOs with other polysaccharide hydrolases is reviewed, and their current problems and future research directions are pointed out.
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Affiliation(s)
- Xiao Guo
- College of Chemical and Biological Engineering, Shandong University of Science and Technology, Qingdao 266590, PR China; Key Laboratory of Industrial Fermentation Microbiology of the Ministry of Education, College of Biotechnology, Tianjin University of Science and Technology, Tianjin 300450, PR China
| | - Yajing An
- Key Laboratory of Industrial Fermentation Microbiology of the Ministry of Education, College of Biotechnology, Tianjin University of Science and Technology, Tianjin 300450, PR China
| | - Fufeng Liu
- Key Laboratory of Industrial Fermentation Microbiology of the Ministry of Education, College of Biotechnology, Tianjin University of Science and Technology, Tianjin 300450, PR China
| | - Fuping Lu
- Key Laboratory of Industrial Fermentation Microbiology of the Ministry of Education, College of Biotechnology, Tianjin University of Science and Technology, Tianjin 300450, PR China
| | - Bo Wang
- College of Chemical and Biological Engineering, Shandong University of Science and Technology, Qingdao 266590, PR China.
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27
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Guo J, Fisher OS. Orchestrating copper binding: structure and variations on the cupredoxin fold. J Biol Inorg Chem 2022; 27:529-540. [PMID: 35994119 DOI: 10.1007/s00775-022-01955-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Accepted: 08/07/2022] [Indexed: 11/26/2022]
Abstract
A large number of copper binding proteins coordinate metal ions using a shared three-dimensional fold called the cupredoxin domain. This domain was originally identified in Type 1 "blue copper" centers but has since proven to be a common domain architecture within an increasingly large and diverse group of copper binding domains. The cupredoxin fold has a number of qualities that make it ideal for coordinating Cu ions for purposes including electron transfer, enzyme catalysis, assembly of other copper sites, and copper sequestration. The structural core does not undergo major conformational changes upon metal binding, but variations within the coordination environment of the metal site confer a range of Cu-binding affinities, reduction potentials, and spectroscopic properties. Here, we discuss these proteins from a structural perspective, examining how variations within the overall cupredoxin fold and metal binding sites are linked to distinct spectroscopic properties and biological functions. Expanding far beyond the blue copper proteins, cupredoxin domains are used by a growing number of proteins and enzymes as a means of binding copper ions, with many more likely remaining to be identified.
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Affiliation(s)
- Jing Guo
- Department of Chemistry, Lehigh University, Bethlehem, PA, USA
| | - Oriana S Fisher
- Department of Chemistry, Lehigh University, Bethlehem, PA, USA.
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28
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Long L, Hu Y, Sun F, Gao W, Hao Z, Yin H. Advances in lytic polysaccharide monooxygenases with the cellulose-degrading auxiliary activity family 9 to facilitate cellulose degradation for biorefinery. Int J Biol Macromol 2022; 219:68-83. [PMID: 35931294 DOI: 10.1016/j.ijbiomac.2022.07.240] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2022] [Revised: 07/29/2022] [Accepted: 07/30/2022] [Indexed: 11/18/2022]
Abstract
One crucial step in processing the recalcitrant lignocellulosic biomass is the fast hydrolysis of natural cellulose to fermentable sugars that can be subsequently converted to biofuels and bio-based chemicals. Recent studies have shown that lytic polysaccharide monooxygenase (LPMOs) with auxiliary activity family 9 (AA9) are capable of efficiently depolymerizing the crystalline cellulose via regioselective oxidation reaction. Intriguingly, the catalysis by AA9 LPMOs requires reductant to provide electrons, and lignin and its phenolic derivatives can be oxidized, releasing reductant to activate the reaction. The activity of AA9 LPMOs can be enhanced by in-situ generation of H2O2 in the presence of O2. Although scientific understanding of these enzymes remains somewhat unknown or controversial, structure modifications on AA9 LPMOs through protein engineering have emerged in recent years, which are prerequisite for their extensive applications in the development of cellulase-mediated lignocellulosic biorefinery processes. In this review, we critically comment on advances in studies for AA9 LPMOs, i.e., characteristic of AA9 LPMOs catalysis, external electron donors to AA9 LPMOs, especially the role of the oxidization of lignin and its derivatives, and AA9 LPMOs protein engineering as well as their extensive applications in the bioprocessing of lignocellulosic biomass. Perspectives are also highlighted for addressing the challenges.
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Affiliation(s)
- Lingfeng Long
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Yun Hu
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Fubao Sun
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, China.
| | - Wa Gao
- Dalian Engineering Research Center for Carbohydrate Agricultural Preparations, Liaoning Provincial Key Laboratory of Carbohydrates, Dalian Institute of Chemical Physics, Chinese Academy of Sciences (CAS(, Dalian 116023, China
| | - Zhikui Hao
- Institute of Applied Biotechnology, School of Medicine and Pharmaceutical Engineering, Taizhou Vocational and Technical College, Taizhou 318000, China
| | - Heng Yin
- Dalian Engineering Research Center for Carbohydrate Agricultural Preparations, Liaoning Provincial Key Laboratory of Carbohydrates, Dalian Institute of Chemical Physics, Chinese Academy of Sciences (CAS(, Dalian 116023, China
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29
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Magri S, Nazerian G, Segato T, Vieira Monclaro A, Zarattini M, Segato F, Polikarpov I, Cannella D. Polymer ultrastructure governs AA9 lytic polysaccharide monooxygenases functionalization and deconstruction efficacy on cellulose nano-crystals. BIORESOURCE TECHNOLOGY 2022; 347:126375. [PMID: 34801726 DOI: 10.1016/j.biortech.2021.126375] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Revised: 11/14/2021] [Accepted: 11/15/2021] [Indexed: 06/13/2023]
Abstract
Lytic Polysaccharide MonoOxygenases display great variability towards cellulose ultrastructure while performing oxidative functionalization of the polymers. Aiming at employing AA9-LPMOs for isolation of cellulose nano-crystals (CNCs), the ratio between functionalization/crystalline degradation became a crucial parameter. Here are reported the constraints posed by the substrate ultrastructure on the activity of seven different AA9 LPMOs representative of various regioselectivity and substrate affinity: TtAA9E, TaAA9A, PcAA9D, MtAA9A, MtAA9D, MtAA9I-CBM and MtAA9J. The substrate crystallinity and dry matter loading greatly affected the seven AA9s in an enzyme-specific manner, impacting their efficiency for CNCs functionalization purposes. X-ray diffraction pattern analyses were used to assess the cracking efficacy of the enzymatic treatment to de-crystallize CNCs, revealing that those AA9s with minor efficiency in releasing oligosaccharides resulted instead the most disruptive towards the crystal lattice and in reducing the particle sizes. These non-catalytic effects were found comparable with the one caused by the expansin BsEXLX1 enzyme.
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Affiliation(s)
- Silvia Magri
- Photobiocatalysis Unit - CPBL, and Biomass Transformation Lab - BTL, École Interfacultaire de Bioingénieurs, Université Libre de Bruxelles, Belgium
| | - Gulsen Nazerian
- Photobiocatalysis Unit - CPBL, and Biomass Transformation Lab - BTL, École Interfacultaire de Bioingénieurs, Université Libre de Bruxelles, Belgium
| | - Tiriana Segato
- 4Mat, Ecole Polytechnique de Bruxelles, Université Libre de Bruxelles, Belgium
| | - Antonielle Vieira Monclaro
- Photobiocatalysis Unit - CPBL, and Biomass Transformation Lab - BTL, École Interfacultaire de Bioingénieurs, Université Libre de Bruxelles, Belgium
| | - Marco Zarattini
- Photobiocatalysis Unit - CPBL, and Biomass Transformation Lab - BTL, École Interfacultaire de Bioingénieurs, Université Libre de Bruxelles, Belgium
| | - Fernando Segato
- Synthetic and Molecular Biology Laboratory (SyMB), Department of Biotechnology, Lorena School of Engineering, University of São Paulo, Lorena, SP, Brazil
| | - Igor Polikarpov
- São Carlos Institute of Physics, University of São Paulo, São Carlos, SP, Brazil
| | - David Cannella
- Photobiocatalysis Unit - CPBL, and Biomass Transformation Lab - BTL, École Interfacultaire de Bioingénieurs, Université Libre de Bruxelles, Belgium.
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30
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Karnaouri A, Chorozian K, Zouraris D, Karantonis A, Topakas E, Rova U, Christakopoulos P. Lytic polysaccharide monooxygenases as powerful tools in enzymatically assisted preparation of nano-scaled cellulose from lignocellulose: A review. BIORESOURCE TECHNOLOGY 2022; 345:126491. [PMID: 34871721 DOI: 10.1016/j.biortech.2021.126491] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 11/28/2021] [Accepted: 11/30/2021] [Indexed: 06/13/2023]
Abstract
Nanocellulose, either in the form of fibers or crystals, constitutes a renewable, biobased, biocompatible material with advantageous mechanical properties that can be isolated from lignocellulosic biomass. Enzyme-assisted isolation of nanocellulose is an attractive, environmentally friendly approach that leads to products of higher quality compared to their chemically prepared counterparts. Lytic polysaccharide monooxygenases (LPMOs) are enzymes that oxidatively cleave the β-1,4-glycosidic bond of polysaccharides upon activation of O2 or H2O2 and presence of an electron donor. Their use for treatment of cellulose fibers towards the preparation of nano-scaled cellulose is related to the ability of LPMOs to create nicking points on the fiber surface, thus facilitating fiber disruption and separation. The aim of this review is to describe the mode of action of LPMOs on cellulose fibers towards the isolation of nanostructures, thus highlighting their great potential for the production of nanocellulose as a novel value added product from lignocellulose.
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Affiliation(s)
- Anthi Karnaouri
- Industrial Biotechnology & Biocatalysis Group, Biotechnology Lab, School of Chemical Engineering, National Technical University of Athens, 9 Iroon Polytechniou Str., Zografou Campus, 15780 Athens, Greece; Biochemical Process Engineering, Chemical Engineering, Department of Civil, Environmental and Natural Resources Engineering, Luleå University of Technology, Luleå, Sweden.
| | - Koar Chorozian
- Industrial Biotechnology & Biocatalysis Group, Biotechnology Lab, School of Chemical Engineering, National Technical University of Athens, 9 Iroon Polytechniou Str., Zografou Campus, 15780 Athens, Greece
| | - Dimitrios Zouraris
- Laboratory of Physical Chemistry and Applied Electrochemistry, School of Chemical Engineering, National Technical University of Athens, Zografou, 15780 Athens, Greece
| | - Antonis Karantonis
- Laboratory of Physical Chemistry and Applied Electrochemistry, School of Chemical Engineering, National Technical University of Athens, Zografou, 15780 Athens, Greece
| | - Evangelos Topakas
- Industrial Biotechnology & Biocatalysis Group, Biotechnology Lab, School of Chemical Engineering, National Technical University of Athens, 9 Iroon Polytechniou Str., Zografou Campus, 15780 Athens, Greece
| | - Ulrika Rova
- Biochemical Process Engineering, Chemical Engineering, Department of Civil, Environmental and Natural Resources Engineering, Luleå University of Technology, Luleå, Sweden
| | - Paul Christakopoulos
- Biochemical Process Engineering, Chemical Engineering, Department of Civil, Environmental and Natural Resources Engineering, Luleå University of Technology, Luleå, Sweden
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31
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Purification and Structural Characterization of the Auxiliary Activity 9 Native Lytic Polysaccharide Monooxygenase from Thermoascus aurantiacus and Identification of Its C1- and C4-Oxidized Reaction Products. Catalysts 2022. [DOI: 10.3390/catal12020139] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
Auxiliary activity 9 (AA9) lytic polysaccharide monooxygenases (LPMOs) are copper-dependent oxidoreductases that use O2 or H2O2 to perform oxidative cleavage of cellulose in the presence of an electron donor. Combined with cellulases, they can assist in a more efficient cleavage of cellulose. AA9 LPMOs have therefore attracted considerable attention in recent years for use in biotechnological applications. Here, a native AA9 LPMO (nTaAA9A) from the thermophilic fungus Thermoascus aurantiacus was purified and characterized. The enzyme was shown to be active and able to cleave cellulose and xylan to produce C1- and C4-oxidized products. It was also found to retain about 84.3, 63.7, and 35.3% of its activity after incubation for 30 min at 60, 70, and 80 °C, respectively, using quantitative activity determination. The structure was determined to 1.36 Å resolution and compared with that of the recombinant enzyme expressed in Aspergillus oryzae. Structural differences in the glycosylated Asn138 and in solvent-exposed loops were identified.
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32
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Méndez-Líter JA, Ayuso-Fernández I, Csarman F, de Eugenio LI, Míguez N, Plou FJ, Prieto A, Ludwig R, Martínez MJ. Lytic Polysaccharide Monooxygenase from Talaromyces amestolkiae with an Enigmatic Linker-like Region: The Role of This Enzyme on Cellulose Saccharification. Int J Mol Sci 2021; 22:13611. [PMID: 34948409 PMCID: PMC8703934 DOI: 10.3390/ijms222413611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Revised: 12/14/2021] [Accepted: 12/16/2021] [Indexed: 11/30/2022] Open
Abstract
The first lytic polysaccharide monooxygenase (LPMO) detected in the genome of the widespread ascomycete Talaromyces amestolkiae (TamAA9A) has been successfully expressed in Pichia pastoris and characterized. Molecular modeling of TamAA9A showed a structure similar to those from other AA9 LPMOs. Although fungal LPMOs belonging to the genera Penicillium or Talaromyces have not been analyzed in terms of regioselectivity, phylogenetic analyses suggested C1/C4 oxidation which was confirmed by HPAEC. To ascertain the function of a C-terminal linker-like region present in the wild-type sequence of the LPMO, two variants of the wild-type enzyme, one without this sequence and one with an additional C-terminal carbohydrate binding domain (CBM), were designed. The three enzymes (native, without linker and chimeric variant with a CBM) were purified in two chromatographic steps and were thermostable and active in the presence of H2O2. The transition midpoint temperature of the wild-type LPMO (Tm = 67.7 °C) and its variant with only the catalytic domain (Tm = 67.6 °C) showed the highest thermostability, whereas the presence of a CBM reduced it (Tm = 57.8 °C) and indicates an adverse effect on the enzyme structure. Besides, the potential of the different T. amestolkiae LPMO variants for their application in the saccharification of cellulosic and lignocellulosic materials was corroborated.
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Affiliation(s)
- Juan Antonio Méndez-Líter
- Department of Microbial and Plant Biotechnology, Centro de Investigaciones Biológicas Margarita Salas, Spanish National Research Council (CSIC), Ramiro de Maeztu 9, 28040 Madrid, Spain; (J.A.M.-L.); (L.I.d.E.); (A.P.)
| | - Iván Ayuso-Fernández
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), 1462 Ås, Norway;
| | - Florian Csarman
- Department of Food Science and Technology, BOKU–University of Natural Resources and Life Sciences, Muthgasse 11, 1190 Vienna, Austria; (F.C.); (R.L.)
| | - Laura Isabel de Eugenio
- Department of Microbial and Plant Biotechnology, Centro de Investigaciones Biológicas Margarita Salas, Spanish National Research Council (CSIC), Ramiro de Maeztu 9, 28040 Madrid, Spain; (J.A.M.-L.); (L.I.d.E.); (A.P.)
| | - Noa Míguez
- Instituto de Catálisis y Petroleoquímica, Spanish National Research Council (CSIC), Marie Curie 2, 28049 Madrid, Spain; (N.M.); (F.J.P.)
| | - Francisco J. Plou
- Instituto de Catálisis y Petroleoquímica, Spanish National Research Council (CSIC), Marie Curie 2, 28049 Madrid, Spain; (N.M.); (F.J.P.)
| | - Alicia Prieto
- Department of Microbial and Plant Biotechnology, Centro de Investigaciones Biológicas Margarita Salas, Spanish National Research Council (CSIC), Ramiro de Maeztu 9, 28040 Madrid, Spain; (J.A.M.-L.); (L.I.d.E.); (A.P.)
| | - Roland Ludwig
- Department of Food Science and Technology, BOKU–University of Natural Resources and Life Sciences, Muthgasse 11, 1190 Vienna, Austria; (F.C.); (R.L.)
| | - María Jesús Martínez
- Department of Microbial and Plant Biotechnology, Centro de Investigaciones Biológicas Margarita Salas, Spanish National Research Council (CSIC), Ramiro de Maeztu 9, 28040 Madrid, Spain; (J.A.M.-L.); (L.I.d.E.); (A.P.)
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Quantifying Oxidation of Cellulose-Associated Glucuronoxylan by Two Lytic Polysaccharide Monooxygenases from Neurospora crassa. Appl Environ Microbiol 2021; 87:e0165221. [PMID: 34613755 PMCID: PMC8612270 DOI: 10.1128/aem.01652-21] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Family AA9 lytic polysaccharide monooxygenases (LPMOs) are abundant in fungi, where they catalyze oxidative depolymerization of recalcitrant plant biomass. These AA9 LPMOs cleave cellulose and some also act on hemicelluloses, primarily other (substituted) β-(1→4)-glucans. Oxidative cleavage of xylan has been shown for only a few AA9 LPMOs, and it remains unclear whether this activity is a minor side reaction or primary function. Here, we show that Neurospora crassa LPMO9F (NcLPMO9F) and the phylogenetically related, hitherto uncharacterized NcLPMO9L from N. crassa are active on both cellulose and cellulose-associated glucuronoxylan but not on glucuronoxylan alone. A newly developed method for simultaneous quantification of xylan-derived and cellulose-derived oxidized products showed that NcLPMO9F preferentially cleaves xylan when acting on a cellulose–beechwood glucuronoxylan mixture, yielding about three times more xylan-derived than cellulose-derived oxidized products. Interestingly, under similar conditions, NcLPMO9L and the previously characterized McLPMO9H, from Malbranchea cinnamomea, showed different xylan-to-cellulose preferences, giving oxidized product ratios of about 0.5:1 and 1:1, respectively, indicative of functional variation among xylan-active LPMOs. Phylogenetic and structural analysis of xylan-active AA9 LPMOs led to the identification of characteristic structural features, including unique features that do not occur in phylogenetically remote AA9 LPMOs, such as four AA9 LPMOs whose lack of activity toward glucuronoxylan was demonstrated in the present study. Taken together, the results provide a path toward discovery of additional xylan-active LPMOs and show that the huge family of AA9 LPMOs has members that preferentially act on xylan. These findings shed new light on the biological role and industrial potential of these fascinating enzymes. IMPORTANCE Plant cell wall polysaccharides are highly resilient to depolymerization by hydrolytic enzymes, partly due to cellulose chains being tightly packed in microfibrils that are covered by hemicelluloses. Lytic polysaccharide monooxygenases (LPMOs) seem well suited to attack these resilient copolymeric structures, but the occurrence and importance of hemicellulolytic activity among LPMOs remain unclear. Here, we show that certain AA9 LPMOs preferentially cleave xylan when acting on a cellulose–glucuronoxylan mixture, and that this ability is the result of protein evolution that has resulted in a clade of AA9 LPMOs with specific structural features. Our findings strengthen the notion that the vast arsenal of AA9 LPMOs in certain fungal species provides functional versatility and that AA9 LPMOs may have evolved to promote oxidative depolymerization of a wide variety of recalcitrant, copolymeric plant polysaccharide structures. These findings have implications for understanding the biological roles and industrial potential of LPMOs.
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Støpamo FG, Røhr ÅK, Mekasha S, Petrović DM, Várnai A, Eijsink VGH. Characterization of a lytic polysaccharide monooxygenase from Aspergillus fumigatus shows functional variation among family AA11 fungal LPMOs. J Biol Chem 2021; 297:101421. [PMID: 34798071 PMCID: PMC8668981 DOI: 10.1016/j.jbc.2021.101421] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 11/05/2021] [Accepted: 11/08/2021] [Indexed: 11/26/2022] Open
Abstract
The discovery of oxidative cleavage of recalcitrant polysaccharides by lytic polysaccharide monooxygenases (LPMOs) has affected the study and industrial application of enzymatic biomass processing. Despite being widespread in fungi, LPMOs belonging to the auxiliary activity (AA) family AA11 have been understudied. While these LPMOs are considered chitin active, some family members have little or no activity toward chitin, and the only available crystal structure of an AA11 LPMO lacks features found in bacterial chitin-active AA10 LPMOs. Here, we report structural and functional characteristics of a single-domain AA11 LPMO from Aspergillus fumigatus, AfAA11A. The crystal structure shows a substrate-binding surface with features resembling those of known chitin-active LPMOs. Indeed, despite the absence of a carbohydrate-binding module, AfAA11A has considerable affinity for α-chitin and, more so, β-chitin. AfAA11A is active toward both these chitin allomorphs and enhances chitin degradation by an endoacting chitinase, in particular for α-chitin. The catalytic activity of AfAA11A on chitin increases when supplying reactions with hydrogen peroxide, showing that, like LPMOs from other families, AfAA11A has peroxygenase activity. These results show that, in stark contrast to the previously characterized AfAA11B from the same organism, AfAA11A likely plays a role in fungal chitin turnover. Thus, members of the hitherto rather enigmatic family of AA11 LPMOs show considerable structural and functional differences and may have multiple roles in fungal physiology.
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Affiliation(s)
- Fredrik Gjerstad Støpamo
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), Ås, Norway
| | - Åsmund Kjendseth Røhr
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), Ås, Norway
| | - Sophanit Mekasha
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), Ås, Norway
| | - Dejan M Petrović
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), Ås, Norway
| | - Anikó Várnai
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), Ås, Norway
| | - Vincent G H Eijsink
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), Ås, Norway.
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35
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Chromatographic analysis of oxidized cello-oligomers generated by lytic polysaccharide monooxygenases using dual electrolytic eluent generation. J Chromatogr A 2021; 1662:462691. [PMID: 34894418 DOI: 10.1016/j.chroma.2021.462691] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Revised: 11/14/2021] [Accepted: 11/16/2021] [Indexed: 11/20/2022]
Abstract
Research on oligosaccharides, including the complicated product mixtures generated by lytic polysaccharide monooxygenases (LPMOs), is growing at a rapid pace. LPMOs are gaining major interest, and the ability to efficiently and accurately separate and quantify their native and oxidized products chromatographically is essential in furthering our understanding of these oxidative enzymes. Here we present a novel set of methods based on dual electrolytic eluent generation, where the conventional sodium acetate/sodium hydroxide (NaOAc/NaOH) eluents in high-performance anion-exchange chromatography (HPAEC) are replaced by electrolytically-generated potassium methane sulfonate/potassium hydroxide (KMSA/KOH). The new methods separate all compounds of interest within 24-45 min and with high sensitivity; limits of detection and quantification were in the range of 0.0001-0.0032 mM and 0.0002-0.0096 mM, respectively. In addition, an average of 3.5 times improvement in analytical CV was obtained. This chromatographic platform overcomes drawbacks associated with manual preparation of eluents and offers simplified operation and rapid method optimization, with increased precision for less abundant LPMO-derived products.
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36
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Kuusk S, Väljamäe P. Kinetics of H 2O 2-driven catalysis by a lytic polysaccharide monooxygenase from the fungus Trichoderma reesei. J Biol Chem 2021; 297:101256. [PMID: 34597668 PMCID: PMC8528726 DOI: 10.1016/j.jbc.2021.101256] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 09/24/2021] [Accepted: 09/25/2021] [Indexed: 01/17/2023] Open
Abstract
Owing to their ability to break glycosidic bonds in recalcitrant crystalline polysaccharides such as cellulose, the catalysis effected by lytic polysaccharide monooxygenases (LPMOs) is of major interest. Kinetics of these reductant-dependent, monocopper enzymes is complicated by the insoluble nature of the cellulose substrate and parallel, enzyme-dependent, and enzyme-independent side reactions between the reductant and oxygen-containing cosubstrates. Here, we provide kinetic characterization of cellulose peroxygenase (oxidative cleavage of glycosidic bonds in cellulose) and reductant peroxidase (oxidation of the reductant) activities of the LPMO TrAA9A of the cellulose-degrading model fungus Trichoderma reesei. The catalytic efficiency (kcat/Km(H2O2)) of the cellulose peroxygenase reaction (kcat = 8.5 s−1, and Km(H2O2)=30μM) was an order of magnitude higher than that of the reductant (ascorbic acid) peroxidase reaction. The turnover of H2O2 in the ascorbic acid peroxidase reaction followed the ping-pong mechanism and led to irreversible inactivation of the enzyme with a probability of 0.0072. Using theoretical analysis, we suggest a relationship between the half-life of LPMO, the values of kinetic parameters, and the concentrations of the reactants.
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Affiliation(s)
- Silja Kuusk
- Institute of Molecular and Cell Biology, University of Tartu, Tartu, Estonia
| | - Priit Väljamäe
- Institute of Molecular and Cell Biology, University of Tartu, Tartu, Estonia.
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37
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Lee JL, Ross DL, Barman SK, Ziller JW, Borovik AS. C-H Bond Cleavage by Bioinspired Nonheme Metal Complexes. Inorg Chem 2021; 60:13759-13783. [PMID: 34491738 DOI: 10.1021/acs.inorgchem.1c01754] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The functionalization of C-H bonds is one of the most challenging transformations in synthetic chemistry. In biology, these processes are well-known and are achieved with a variety of metalloenzymes, many of which contain a single metal center within their active sites. The most well studied are those with Fe centers, and the emerging experimental data show that high-valent iron oxido species are the intermediates responsible for cleaving the C-H bond. This Forum Article describes the state of this field with an emphasis on nonheme Fe enzymes and current experimental results that provide insights into the properties that make these species capable of C-H bond cleavage. These parameters are also briefly considered in regard to manganese oxido complexes and Cu-containing metalloenzymes. Synthetic iron oxido complexes are discussed to highlight their utility as spectroscopic and mechanistic probes and reagents for C-H bond functionalization. Avenues for future research are also examined.
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Affiliation(s)
- Justin L Lee
- Department of Chemistry, University of California-Irvine, 1102 Natural Sciences II, Irvine, California 92697, United States
| | - Dolores L Ross
- Department of Chemistry, University of California-Irvine, 1102 Natural Sciences II, Irvine, California 92697, United States
| | - Suman K Barman
- Department of Chemistry, University of California-Irvine, 1102 Natural Sciences II, Irvine, California 92697, United States
| | - Joseph W Ziller
- Department of Chemistry, University of California-Irvine, 1102 Natural Sciences II, Irvine, California 92697, United States
| | - A S Borovik
- Department of Chemistry, University of California-Irvine, 1102 Natural Sciences II, Irvine, California 92697, United States
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Rieder L, Petrović D, Väljamäe P, Eijsink VG, Sørlie M. Kinetic Characterization of a Putatively Chitin-Active LPMO Reveals a Preference for Soluble Substrates and Absence of Monooxygenase Activity. ACS Catal 2021; 11:11685-11695. [PMID: 34567832 PMCID: PMC8453653 DOI: 10.1021/acscatal.1c03344] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Revised: 08/24/2021] [Indexed: 12/23/2022]
Abstract
![]()
Enzymes known as
lytic polysaccharide monooxygenases (LPMOs) are
recognized as important contributors to aerobic enzymatic degradation
of recalcitrant polysaccharides such as chitin and cellulose. LPMOs
are remarkably abundant in nature, with some fungal species possessing
more than 50 LPMO genes, and the biological implications of this diversity
remain enigmatic. For example, chitin-active LPMOs have been encountered
in biological niches where chitin conversion does not seem to take
place. We have carried out an in-depth kinetic characterization of
a putatively chitin-active LPMO from Aspergillus fumigatus (AfAA11B), which, as we show here, has multiple
unusual properties, such as a low redox potential and high oxidase
activity. Furthermore, AfAA11B is hardly active on
chitin, while being very active on soluble oligomers of N-acetylglucosamine. In the presence of chitotetraose, the enzyme
can withstand considerable amounts of H2O2,
which it uses to efficiently and stoichiometrically convert this substrate.
The unique properties of AfAA11B allowed experiments
showing that it is a strict peroxygenase and does not catalyze a monooxygenase
reaction. This study shows that nature uses LPMOs for breaking glycosidic
bonds in non-polymeric substrates in reactions that depend on H2O2. The quest for the true substrates of these
enzymes, possibly carbohydrates in the cell wall of the fungus or
its competitors, will be of major interest.
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Affiliation(s)
- Lukas Rieder
- Faculty of Chemistry, Biotechnology, and Food Sciences, Norwegian University of Life Sciences (NMBU), Ås N-1432, Norway
| | - Dejan Petrović
- Faculty of Chemistry, Biotechnology, and Food Sciences, Norwegian University of Life Sciences (NMBU), Ås N-1432, Norway
| | - Priit Väljamäe
- Institute of Molecular and Cell Biology, University of Tartu, Tartu 50090, Estonia
| | - Vincent G.H. Eijsink
- Faculty of Chemistry, Biotechnology, and Food Sciences, Norwegian University of Life Sciences (NMBU), Ås N-1432, Norway
| | - Morten Sørlie
- Faculty of Chemistry, Biotechnology, and Food Sciences, Norwegian University of Life Sciences (NMBU), Ås N-1432, Norway
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Rani Singhania R, Dixit P, Kumar Patel A, Shekher Giri B, Kuo CH, Chen CW, Di Dong C. Role and significance of lytic polysaccharide monooxygenases (LPMOs) in lignocellulose deconstruction. BIORESOURCE TECHNOLOGY 2021; 335:125261. [PMID: 34000697 DOI: 10.1016/j.biortech.2021.125261] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 05/03/2021] [Accepted: 05/05/2021] [Indexed: 05/27/2023]
Abstract
Lytic polysaccharide monooxygenases (LPMOs) emerged a decade ago and have been described as biomass deconstruction boosters as they play an extremely important role in unravelling the enzymatic biomass hydrolysis scheme. These are oxidative enzymes requiring partners to donate electrons during catalytic action on cellulose backbone. Commercial cellulase preparations are mostly from the robust fungal sources, hence LPMOs from fungi (AA9) have been discussed. Characterisation of LPMOs suffers due to multiple complications which has been discussed and challenges in detection of LPMOs in secretomes has also been highlighted. This review focuses on the significance of LPMOs on biomass hydrolysis due to which it has become a key component of cellulolytic cocktail available commercially for biomass deconstruction and its routine analysis challenge has also been discussed. It has also outlined a few key points that help in expressing catalytic active recombinant AA9 LPMOs.
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Affiliation(s)
- Reeta Rani Singhania
- Department of Marine Environmental Engineering, National Kaohsiung University of Science and Technology, Kaohsiung City, Taiwan
| | - Pooja Dixit
- Department of Chemistry, Umeå University, SE-90187 Umeå, Sweden
| | - Anil Kumar Patel
- Department of Marine Environmental Engineering, National Kaohsiung University of Science and Technology, Kaohsiung City, Taiwan
| | - Balendu Shekher Giri
- Department of Chemical Engineering, Indian Institute of Technology, Guwahati 781039 India
| | - Chia-Hung Kuo
- Department of Seafood Science, National Kaohsiung University of Science and Technology, Kaohsiung City, Taiwan
| | - Chiu-Wen Chen
- Department of Marine Environmental Engineering, National Kaohsiung University of Science and Technology, Kaohsiung City, Taiwan
| | - Cheng Di Dong
- Department of Marine Environmental Engineering, National Kaohsiung University of Science and Technology, Kaohsiung City, Taiwan.
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40
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Damle MS, Singh AN, Peters SC, Szalai VA, Fisher OS. The YcnI protein from Bacillus subtilis contains a copper-binding domain. J Biol Chem 2021; 297:101078. [PMID: 34400169 PMCID: PMC8424229 DOI: 10.1016/j.jbc.2021.101078] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Revised: 08/06/2021] [Accepted: 08/11/2021] [Indexed: 11/26/2022] Open
Abstract
Bacteria require a precise balance of copper ions to ensure that essential cuproproteins are fully metalated while also avoiding copper-induced toxicity. The Gram-positive bacterium Bacillus subtilis maintains appropriate copper homeostasis in part through the ycn operon. The ycn operon comprises genes encoding three proteins: the putative copper importer YcnJ, the copper-dependent transcriptional repressor YcnK, and the uncharacterized Domain of Unknown Function 1775 (DUF1775) containing YcnI. DUF1775 domains are found across bacterial phylogeny, and bioinformatics analyses indicate that they frequently neighbor domains implicated in copper homeostasis and transport. Here, we investigated whether YcnI can interact with copper and, using electron paramagnetic resonance and inductively coupled plasma-MS, found that this protein can bind a single Cu(II) ion. We determine the structure of both the apo and copper-bound forms of the protein by X-ray crystallography, uncovering a copper-binding site featuring a unique monohistidine brace ligand set that is highly conserved among DUF1775 domains. These data suggest a possible role for YcnI as a copper chaperone and that DUF1775 domains in other bacterial species may also function in copper homeostasis.
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Affiliation(s)
- Madhura S Damle
- Department of Chemistry, Lehigh University, Bethlehem, Pennsylvania, USA
| | - Aarshi N Singh
- Department of Chemistry, Lehigh University, Bethlehem, Pennsylvania, USA
| | - Stephen C Peters
- Department of Earth and Environmental Sciences, Lehigh University, Bethlehem, Pennsylvania, USA
| | - Veronika A Szalai
- Physical Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, Maryland, USA
| | - Oriana S Fisher
- Department of Chemistry, Lehigh University, Bethlehem, Pennsylvania, USA.
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Mazurkewich S, Seveso A, Hüttner S, Brändén G, Larsbrink J. Structure of a C1/C4-oxidizing AA9 lytic polysaccharide monooxygenase from the thermophilic fungus Malbranchea cinnamomea. Acta Crystallogr D Struct Biol 2021; 77:1019-1026. [PMID: 34342275 PMCID: PMC8329866 DOI: 10.1107/s2059798321006628] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2021] [Accepted: 06/25/2021] [Indexed: 11/20/2022] Open
Abstract
The thermophilic fungus Malbranchea cinnamomea contains a host of enzymes that enable its ability as an efficient degrader of plant biomass and that could be mined for industrial applications. This thermophilic fungus has been studied and found to encode eight lytic polysaccharide monooxygenases (LPMOs) from auxiliary activity family 9 (AA9), which collectively possess different substrate specificities for a range of plant cell-wall-related polysaccharides and oligosaccharides. To gain greater insight into the molecular determinants defining the different specificities, structural studies were pursued and the structure of McAA9F was determined. The enzyme contains the immunoglobulin-like fold typical of previously solved AA9 LPMO structures, but contains prominent differences in the loop regions found on the surface of the substrate-binding site. Most significantly, McAA9F has a broad substrate specificity, with activity on both crystalline and soluble polysaccharides. Moreover, it contains a small loop in a region where a large loop has been proposed to govern specificity towards oligosaccharides. The presence of the small loop leads to a considerably flatter and more open surface that is likely to enable the broad specificity of the enzyme. The enzyme contains a succinimide residue substitution, arising from intramolecular cyclization of Asp10, at a position where several homologous members contain an equivalent residue but cyclization has not previously been observed. This first structure of an AA9 LPMO from M. cinnamomea aids both the understanding of this family of enzymes and the exploration of the repertoire of industrially relevant lignocellulolytic enzymes from this fungus.
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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
| | - Andrea Seveso
- Wallenberg Wood Science Center, Division of Industrial Biotechnology, Department of Biology and Biological Engineering, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden
| | - Silvia Hüttner
- Wallenberg Wood Science Center, Division of Industrial Biotechnology, Department of Biology and Biological Engineering, Chalmers University of Technology, SE-412 96 Gothenburg, Sweden
| | - Gisela Brändén
- Department of Chemistry and Molecular Biology, University of Gothenburg, SE-405 30 Gothenburg, Sweden
| | - 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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42
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Calderaro F, Bevers LE, van den Berg MA. Oxidative Power: Tools for Assessing LPMO Activity on Cellulose. Biomolecules 2021; 11:biom11081098. [PMID: 34439765 PMCID: PMC8391687 DOI: 10.3390/biom11081098] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2021] [Revised: 07/19/2021] [Accepted: 07/22/2021] [Indexed: 01/22/2023] Open
Abstract
Lytic polysaccharide monooxygenases (LPMOs) have sparked a lot of research regarding their fascinating mode-of-action. Particularly, their boosting effect on top of the well-known cellulolytic enzymes in lignocellulosic hydrolysis makes them industrially relevant targets. As more characteristics of LPMO and its key role have been elucidated, the need for fast and reliable methods to assess its activity have become clear. Several aspects such as its co-substrates, electron donors, inhibiting factors, and the inhomogeneity of lignocellulose had to be considered during experimental design and data interpretation, as they can impact and often hamper outcomes. This review provides an overview of the currently available methods to measure LPMO activity, including their potential and limitations, and it is illustrated with practical examples.
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Affiliation(s)
- Federica Calderaro
- DSM Biotechnology Center, 2613 AX Delft, The Netherlands; (L.E.B.); (M.A.v.d.B.)
- Molecular Enzymolog y Group, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
- Correspondence: ; Tel.: +31-6-36028569
| | - Loes E. Bevers
- DSM Biotechnology Center, 2613 AX Delft, The Netherlands; (L.E.B.); (M.A.v.d.B.)
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43
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Sethupathy S, Morales GM, Li Y, Wang Y, Jiang J, Sun J, Zhu D. Harnessing microbial wealth for lignocellulose biomass valorization through secretomics: a review. BIOTECHNOLOGY FOR BIOFUELS 2021; 14:154. [PMID: 34225772 PMCID: PMC8256616 DOI: 10.1186/s13068-021-02006-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Accepted: 06/26/2021] [Indexed: 05/10/2023]
Abstract
The recalcitrance of lignocellulosic biomass is a major constraint to its high-value use at industrial scale. In nature, microbes play a crucial role in biomass degradation, nutrient recycling and ecosystem functioning. Therefore, the use of microbes is an attractive way to transform biomass to produce clean energy and high-value compounds. The microbial degradation of lignocelluloses is a complex process which is dependent upon multiple secreted enzymes and their synergistic activities. The availability of the cutting edge proteomics and highly sensitive mass spectrometry tools make possible for researchers to probe the secretome of microbes and microbial consortia grown on different lignocelluloses for the identification of hydrolytic enzymes of industrial interest and their substrate-dependent expression. This review summarizes the role of secretomics in identifying enzymes involved in lignocelluloses deconstruction, the development of enzyme cocktails and the construction of synthetic microbial consortia for biomass valorization, providing our perspectives to address the current challenges.
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Affiliation(s)
- Sivasamy Sethupathy
- School of the Environment and Safety Engineering, Biofuels Institute, Jiangsu University, Zhenjiang, 212013, Jiangsu, China
| | - Gabriel Murillo Morales
- School of the Environment and Safety Engineering, Biofuels Institute, Jiangsu University, Zhenjiang, 212013, Jiangsu, China
| | - Yixuan Li
- School of the Environment and Safety Engineering, Biofuels Institute, Jiangsu University, Zhenjiang, 212013, Jiangsu, China
| | - Yongli Wang
- School of the Environment and Safety Engineering, Biofuels Institute, Jiangsu University, Zhenjiang, 212013, Jiangsu, China
| | - Jianxiong Jiang
- School of the Environment and Safety Engineering, Biofuels Institute, Jiangsu University, Zhenjiang, 212013, Jiangsu, China
| | - Jianzhong Sun
- School of the Environment and Safety Engineering, Biofuels Institute, Jiangsu University, Zhenjiang, 212013, Jiangsu, China
| | - Daochen Zhu
- School of the Environment and Safety Engineering, Biofuels Institute, Jiangsu University, Zhenjiang, 212013, Jiangsu, China.
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Manavalan T, Stepnov AA, Hegnar OA, Eijsink VGH. Sugar oxidoreductases and LPMOs - two sides of the same polysaccharide degradation story? Carbohydr Res 2021; 505:108350. [PMID: 34049079 DOI: 10.1016/j.carres.2021.108350] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2021] [Revised: 05/13/2021] [Accepted: 05/14/2021] [Indexed: 12/20/2022]
Abstract
Lytic polysaccharide monooxygenases (LPMOs) catalyze the oxidative cleavage of glycosidic bonds in recalcitrant polysaccharides such as chitin and cellulose and their discovery has revolutionized our understanding of enzymatic biomass conversion. The discovery of LPMOs raises interesting new questions regarding the roles of other oxidoreductases and abiotic redox processes in biomass conversion. LPMOs need reducing power and an oxygen co-substrate and biomass degrading ecosystems contain a multitude of redox enzymes that affect the availability of both. For example, biomass degrading fungi produce multiple sugar oxidoreductases whose biological functions so far have remained somewhat enigmatic. It is now conceivable that these redox enzymes, in particular H2O2-producing sugar oxidases, could play a role in fueling and controlling LPMO reactions. Here, we shortly review contemporary issues in the LPMO field, paying particular attention to the possible roles of sugar oxidoreductases.
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Affiliation(s)
- Tamilvendan Manavalan
- Faculty of Chemistry, Biotechnology and Food Science, NMBU - Norwegian University of Life Science, N-1432, Ås, Norway
| | - Anton A Stepnov
- Faculty of Chemistry, Biotechnology and Food Science, NMBU - Norwegian University of Life Science, N-1432, Ås, Norway
| | - Olav A Hegnar
- Faculty of Chemistry, Biotechnology and Food Science, NMBU - Norwegian University of Life Science, N-1432, Ås, Norway
| | - Vincent G H Eijsink
- Faculty of Chemistry, Biotechnology and Food Science, NMBU - Norwegian University of Life Science, N-1432, Ås, Norway.
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45
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Rieder L, Ebner K, Glieder A, Sørlie M. Novel molecular biological tools for the efficient expression of fungal lytic polysaccharide monooxygenases in Pichia pastoris. BIOTECHNOLOGY FOR BIOFUELS 2021; 14:122. [PMID: 34044872 PMCID: PMC8161572 DOI: 10.1186/s13068-021-01971-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2021] [Accepted: 05/13/2021] [Indexed: 05/13/2023]
Abstract
BACKGROUND Lytic polysaccharide monooxygenases (LPMOs) are attracting large attention due their ability to degrade recalcitrant polysaccharides in biomass conversion and to perform powerful redox chemistry. RESULTS We have established a universal Pichia pastoris platform for the expression of fungal LPMOs using state-of-the-art recombination cloning and modern molecular biological tools to achieve high yields from shake-flask cultivation and simple tag-less single-step purification. Yields are very favorable with up to 42 mg per liter medium for four different LPMOs spanning three different families. Moreover, we report for the first time of a yeast-originating signal peptide from the dolichyl-diphosphooligosaccharide-protein glycosyltransferase subunit 1 (OST1) form S. cerevisiae efficiently secreting and successfully processes the N-terminus of LPMOs yielding in fully functional enzymes. CONCLUSION The work demonstrates that the industrially most relevant expression host P. pastoris can be used to express fungal LPMOs from different families in high yields and inherent purity. The presented protocols are standardized and require little equipment with an additional advantage with short cultivation periods.
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Affiliation(s)
- Lukas Rieder
- Faculty of Chemistry, Biotechnology, and Food Sciences, Norwegian University of Life Sciences (NMBU), Ås, Norway
| | | | - Anton Glieder
- Institute of Molecular Biotechnology, Graz University of Technology, Petersgasse 14, Graz, Austria
| | - Morten Sørlie
- Faculty of Chemistry, Biotechnology, and Food Sciences, Norwegian University of Life Sciences (NMBU), Ås, Norway.
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46
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Hernández-Rollán C, Falkenberg KB, Rennig M, Bertelsen AB, Ipsen JØ, Brander S, Daley DO, Johansen KS, Nørholm MHH. LyGo: A Platform for Rapid Screening of Lytic Polysaccharide Monooxygenase Production. ACS Synth Biol 2021; 10:897-906. [PMID: 33797234 DOI: 10.1021/acssynbio.1c00034] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Environmentally friendly sources of energy and chemicals are essential constituents of a sustainable society. An important step toward this goal is the utilization of biomass to supply building blocks for future biorefineries. Lytic polysaccharide monooxygenases (LPMOs) are enzymes that play a critical role in breaking the chemical bonds in the most abundant polymers found in recalcitrant biomass, such as cellulose and chitin. To use them in industrial processes they need to be produced in high titers in cell factories. Predicting optimal strategies for producing LPMOs is often nontrivial, and methods allowing for screening several strategies simultaneously are therefore needed. Here, we present a standardized platform for cloning LPMOs. The platform allows users to combine gene fragments with 14 different expression vectors in a simple 15 min reaction, thus enabling rapid exploration of several gene contexts, hosts, and expression strategies in parallel. The open-source LyGo platform is accompanied by easy-to-follow online protocols for both cloning and expression. As a demonstration of its utility, we explore different strategies for expressing several different LPMOs in Escherichia coli, Bacillus subtilis, and Komagataella phaffii.
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Affiliation(s)
- Cristina Hernández-Rollán
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kongens Lyngby, 2800, Denmark
| | - Kristoffer B. Falkenberg
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kongens Lyngby, 2800, Denmark
| | - Maja Rennig
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kongens Lyngby, 2800, Denmark
- Mycropt ApS, Kongens Lyngby, 2800, Denmark
| | - Andreas B. Bertelsen
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kongens Lyngby, 2800, Denmark
| | - Johan Ø. Ipsen
- Department of Plant and Environmental Sciences, University of Copenhagen, Frederiksberg, 1871, Denmark
| | - Søren Brander
- Department of Geosciences and Natural Resource Management, University of Copenhagen, Frederiksberg, 1958, Denmark
| | - Daniel O. Daley
- Mycropt ApS, Kongens Lyngby, 2800, Denmark
- Center for Biomembrane Research, Department of Biochemistry and Biophysics, Stockholm University, Stockholm, 10691, Sweden
| | - Katja S. Johansen
- Department of Geosciences and Natural Resource Management, University of Copenhagen, Frederiksberg, 1958, Denmark
| | - Morten H. H. Nørholm
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Kongens Lyngby, 2800, Denmark
- Mycropt ApS, Kongens Lyngby, 2800, Denmark
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47
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Wang D, Li Y, Zheng Y, Hsieh YSY. Recent Advances in Screening Methods for the Functional Investigation of Lytic Polysaccharide Monooxygenases. Front Chem 2021; 9:653754. [PMID: 33912540 PMCID: PMC8072006 DOI: 10.3389/fchem.2021.653754] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Accepted: 02/12/2021] [Indexed: 01/22/2023] Open
Abstract
Lytic polysaccharide monooxygenase (LPMO) is a newly discovered and widely studied enzyme in recent years. These enzymes play a key role in the depolymerization of sugar-based biopolymers (including cellulose, hemicellulose, chitin and starch), and have a positive significance for biomass conversion. LPMO is a copper-dependent enzyme that can oxidize and cleave glycosidic bonds in cellulose and other polysaccharides. Their mechanism of action depends on the correct coordination of copper ions in the active site. There are still difficulties in the analysis of LPMO activity, which often requires multiple methods to be used in concert. In this review, we discussed various LPMO activity analysis methods reported so far, including mature mass spectrometry, chromatography, labeling, and indirect measurements, and summarized the advantages, disadvantages and applicability of different methods.
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Affiliation(s)
- Damao Wang
- College of Food Science, Southwest University, Chongqing, China
| | - Yanping Li
- College of Food Science, Southwest University, Chongqing, China
| | - Yuting Zheng
- College of Food Science, Southwest University, Chongqing, China
| | - Yves S Y Hsieh
- Division of Glycoscience, Department of Chemistry, School of Engineering Sciences in Chemistry, Biotechnology and Health, Royal Institute of Technology (KTH), AlbaNova University Centre, Stockholm, Sweden.,School of Pharmacy, College of Pharmacy, Taipei Medical University, Taipei, Taiwan.,Genomics Research Center, Academia Sinica, Taipei, Taiwan
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48
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Kadić A, Várnai A, Eijsink VGH, Horn SJ, Lidén G. In situ measurements of oxidation-reduction potential and hydrogen peroxide concentration as tools for revealing LPMO inactivation during enzymatic saccharification of cellulose. BIOTECHNOLOGY FOR BIOFUELS 2021; 14:46. [PMID: 33602308 PMCID: PMC7893893 DOI: 10.1186/s13068-021-01894-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/24/2020] [Accepted: 02/01/2021] [Indexed: 06/12/2023]
Abstract
BACKGROUND Biochemical conversion of lignocellulosic biomass to simple sugars at commercial scale is hampered by the high cost of saccharifying enzymes. Lytic polysaccharide monooxygenases (LPMOs) may hold the key to overcome economic barriers. Recent studies have shown that controlled activation of LPMOs by a continuous H2O2 supply can boost saccharification yields, while overdosing H2O2 may lead to enzyme inactivation and reduce overall sugar yields. While following LPMO action by ex situ analysis of LPMO products confirms enzyme inactivation, currently no preventive measures are available to intervene before complete inactivation. RESULTS Here, we carried out enzymatic saccharification of the model cellulose Avicel with an LPMO-containing enzyme preparation (Cellic CTec3) and H2O2 feed at 1 L bioreactor scale and followed the oxidation-reduction potential and H2O2 concentration in situ with corresponding electrode probes. The rate of oxidation of the reductant as well as the estimation of the amount of H2O2 consumed by LPMOs indicate that, in addition to oxidative depolymerization of cellulose, LPMOs consume H2O2 in a futile non-catalytic cycle, and that inactivation of LPMOs happens gradually and starts long before the accumulation of LPMO-generated oxidative products comes to a halt. CONCLUSION Our results indicate that, in this model system, the collapse of the LPMO-catalyzed reaction may be predicted by the rate of oxidation of the reductant, the accumulation of H2O2 in the reactor or, indirectly, by a clear increase in the oxidation-reduction potential. Being able to monitor the state of the LPMO activity in situ may help maximizing the benefit of LPMO action during saccharification. Overcoming enzyme inactivation could allow improving overall saccharification yields beyond the state of the art while lowering LPMO and, potentially, cellulase loads, both of which would have beneficial consequences on process economics.
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Affiliation(s)
- Adnan Kadić
- Department of Chemical Engineering, Lund University, P.O. Box 118, 221 00, Lund, Sweden
| | - Anikó Várnai
- Faculty of Chemistry, Biotechnology and Food Sciences, Norwegian University of Life Sciences (NMBU), P.O. Box 5003, NO-1432, Ås, Norway
| | - Vincent G H Eijsink
- Faculty of Chemistry, Biotechnology and Food Sciences, Norwegian University of Life Sciences (NMBU), P.O. Box 5003, NO-1432, Ås, Norway
| | - Svein Jarle Horn
- Faculty of Chemistry, Biotechnology and Food Sciences, Norwegian University of Life Sciences (NMBU), P.O. Box 5003, NO-1432, Ås, Norway.
| | - Gunnar Lidén
- Department of Chemical Engineering, Lund University, P.O. Box 118, 221 00, Lund, Sweden.
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Lytic polysaccharide monooxygenases and other histidine-brace copper proteins: structure, oxygen activation and biotechnological applications. Biochem Soc Trans 2021; 49:531-540. [PMID: 33449071 PMCID: PMC7924993 DOI: 10.1042/bst20201031] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2020] [Revised: 12/14/2020] [Accepted: 12/16/2020] [Indexed: 11/17/2022]
Abstract
Lytic polysaccharide monooxygenases (LPMOs) are mononuclear copper enzymes that catalyse the oxidative cleavage of glycosidic bonds. They are characterised by two histidine residues that coordinate copper in a configuration termed the Cu-histidine brace. Although first identified in bacteria and fungi, LPMOs have since been found in all biological kingdoms. LPMOs are now included in commercial enzyme cocktails used in industrial biorefineries. This has led to increased process yield due to the synergistic action of LPMOs with glycoside hydrolases. However, the introduction of LPMOs makes control of the enzymatic step in industrial stirred-tank reactors more challenging, and the operational stability of the enzymes is reduced. It is clear that much is still to be learned about the interaction between LPMOs and their complex natural and industrial environments, and fundamental scientific studies are required towards this end. Several atomic-resolution structures have been solved providing detailed information on the Cu-coordination sphere and the interaction with the polysaccharide substrate. However, the molecular mechanisms of LPMOs are still the subject of intense investigation; the key question being how the proteinaceous environment controls the copper cofactor towards the activation of the O-O bond in O2 and cleavage of the glycosidic bonds in polysaccharides. The need for biochemical characterisation of each putative LPMO is discussed based on recent reports showing that not all proteins with a Cu-histidine brace are enzymes.
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Calderaro F, Keser M, Akeroyd M, Bevers LE, Eijsink VGH, Várnai A, van den Berg MA. Characterization of an AA9 LPMO from Thielavia australiensis, TausLPMO9B, under industrially relevant lignocellulose saccharification conditions. BIOTECHNOLOGY FOR BIOFUELS 2020; 13:195. [PMID: 33292403 PMCID: PMC7706046 DOI: 10.1186/s13068-020-01836-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Accepted: 11/19/2020] [Indexed: 05/02/2023]
Abstract
BACKGROUND The discovery of lytic polysaccharide monooxygenases (LPMO) has changed our perspective on enzymatic degradation of plant biomass. Through an oxidative mechanism, these enzymes are able to cleave and depolymerize various polysaccharides, acting not only on crystalline substrates such as chitin and cellulose, but also on other polysaccharides, such as xyloglucan, glucomannan and starch. Despite their widespread use, uncertainties related to substrate specificity and stereospecificity, the nature of the co-substrate, in-process stability, and the nature of the optimal reductant challenge their exploitation in biomass processing applications. RESULTS In this work, we studied the properties of a novel fungal LPMO from the thermophilic fungus Thielavia australiensis, TausLPMO9B. Heterologous expression of TausLPMO9B in Aspergillus niger yielded a glycosylated protein with a methylated N-terminal histidine showing LPMO activity. High sequence identity of the AA9 domain to that of MtLPMO9B (MYCTH_80312) from Myceliophthora thermophila (84%) indicated strictly C1-oxidizing activity on cellulose, which was confirmed experimentally by the analysis of products released from cellulose using HPAEC. The enzyme was stable and active at a pH ranging from 4 to 6, thus matching the conditions commonly used in industrial biomass processing, where a low pH (between 4 and 5) is used due to the pH-optima of commercial cellulases and a desire to limit microbial contamination. CONCLUSION While the oxidative cleavage of phosphoric acid swollen cellulose (PASC) by TausLPMO9B was boosted by the addition of H2O2 as a co-substrate, this effect was not observed during the saccharification of acid pretreated corn stover. This illustrates key differences between the lab-scale tests with artificial, lignin-free substrates and industrial settings with lignocellulosic biomass as substrate.
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Affiliation(s)
- F Calderaro
- DSM Biotechnology Center, PP 699-0310, Alexander Fleminglaan 1, 2613 AX, Delft, The Netherlands.
- Molecular Enzymology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, The Netherlands.
| | - M Keser
- DSM Biotechnology Center, PP 699-0310, Alexander Fleminglaan 1, 2613 AX, Delft, The Netherlands
| | - M Akeroyd
- DSM Biotechnology Center, PP 699-0310, Alexander Fleminglaan 1, 2613 AX, Delft, The Netherlands
| | - L E Bevers
- DSM Biotechnology Center, PP 699-0310, Alexander Fleminglaan 1, 2613 AX, Delft, The Netherlands
| | - V G H Eijsink
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), Ås, Norway
| | - A Várnai
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), Ås, Norway
| | - M A van den Berg
- DSM Biotechnology Center, PP 699-0310, Alexander Fleminglaan 1, 2613 AX, Delft, The Netherlands
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