1
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Zou Y, Zhang J, Wang J, Gong X, Jiang T, Yan Y. A self-regulated network for dynamically balancing multiple precursors in complex biosynthetic pathways. Metab Eng 2024; 82:69-78. [PMID: 38316239 PMCID: PMC10947840 DOI: 10.1016/j.ymben.2024.02.001] [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: 10/31/2023] [Revised: 01/16/2024] [Accepted: 02/02/2024] [Indexed: 02/07/2024]
Abstract
Microbial synthesis has emerged as a promising and sustainable alternative to traditional chemical synthesis and plant extraction. However, the competition between synthetic pathways and central metabolic pathways for cellular resources may impair final production efficiency. Moreover, when the synthesis of target product requires multiple precursors from the same node, the conflicts of carbon flux have further negative impacts on yields. In this study, a self-regulated network was developed to relieve the competition of precursors in complex synthetic pathways. Using 4-hydroxycoumarin (4-HC) synthetic pathway as a proof of concept, we employed an intermediate as a trigger to dynamically rewire the metabolic flux of pyruvate and control the expression levels of genes in 4-HC synthetic pathway, achieving self-regulation of multiple precursors and enhanced titer. Transcriptomic analysis results additionally demonstrated that the gene transcriptional levels of both pyruvate kinase PykF and synthetic pathway enzyme SdgA dynamically changed according to the intermediate concentrations. Overall, our work established a self-regulated network to dynamically balance the metabolic flux of two precursors in 4-HC biosynthesis, providing insight into balancing biosynthetic pathways where multiple precursors compete and interfere with each other.
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Affiliation(s)
- Yusong Zou
- School of Chemical, Materials and Biomedical Engineering, College of Engineering, The University of Georgia, Athens, GA, 30602, USA
| | - Jianli Zhang
- School of Chemical, Materials and Biomedical Engineering, College of Engineering, The University of Georgia, Athens, GA, 30602, USA
| | - Jian Wang
- School of Chemical, Materials and Biomedical Engineering, College of Engineering, The University of Georgia, Athens, GA, 30602, USA
| | - Xinyu Gong
- School of Chemical, Materials and Biomedical Engineering, College of Engineering, The University of Georgia, Athens, GA, 30602, USA
| | - Tian Jiang
- School of Chemical, Materials and Biomedical Engineering, College of Engineering, The University of Georgia, Athens, GA, 30602, USA
| | - Yajun Yan
- School of Chemical, Materials and Biomedical Engineering, College of Engineering, The University of Georgia, Athens, GA, 30602, USA.
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2
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Sami N, Afzal B, Yasin D, Fatma T. Biochemical Characterization of Laccase from Spirulina CPCC-695 and Their Role in Estrone Degradation. Protein J 2024; 43:115-128. [PMID: 38127183 DOI: 10.1007/s10930-023-10169-7] [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] [Accepted: 11/13/2023] [Indexed: 12/23/2023]
Abstract
The addition of exogenous endocrine disrupting compounds (EDCs) like estrone, in the food chain through the aquatic system, disrupts steroid biosynthesis and metabolism by altering either the genomic or non-genomic pathway that eventually results in various diseases. Thus, bioremediation of these compounds is urgently required to prevent their addition and persistence in the environment. Enzymatic degradation has proven to be a knight in shining armour as it is safe and generates no toxic products. The multicopper oxidases (E.C. 1.10.3.2 benzenediol: oxygen oxidoreductase), laccase with the potential to degrade both phenolic and non-phenolic substrates has recently gained attention. In this study, the laccase was purified, characterized, and used to study estrone degradation. The culture filtrate (crude laccase) was concentrated and precipitated using cold-acetone and dialyzed against tris buffer (50 mM) giving a four-fold partially purified form, with 45.56% yield and 204.14 U/mg as specific activity and a single peak at 250-300 nm. The partially purified laccase was approximately 80 kDa as estimated by SDS-PAGE preferred ABTS as substrate. Both crude and partially purified laccase showed maximum activity at pH 3.0, 40 °C, and 4 mM ABTS. Kinetic constants (Km, Vmax) of crude and partially purified laccase were found to be 0.83 mM; 494.31 mM/min, and 0.58 mM; 480.54 mM/min respectively. Iron sulphate and sodium azide inhibited laccase maximally. Crude and partially purified laccase degradation efficiency was 87.55 and 91.35% respectively. Spirulina CPCC-695 laccase with efficient estrone degradation ability renders them promising candidates for EDCs bioremediation.
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Affiliation(s)
- Neha Sami
- Cyanobacterial Biotechnology Laboratory, Department of Biosciences, Jamia Millia Islamia, New Delhi, India
| | - Bushra Afzal
- Cyanobacterial Biotechnology Laboratory, Department of Biosciences, Jamia Millia Islamia, New Delhi, India
| | - Durdana Yasin
- Cyanobacterial Biotechnology Laboratory, Department of Biosciences, Jamia Millia Islamia, New Delhi, India
| | - Tasneem Fatma
- Cyanobacterial Biotechnology Laboratory, Department of Biosciences, Jamia Millia Islamia, New Delhi, India.
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3
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Aza P, Camarero S. Fungal Laccases: Fundamentals, Engineering and Classification Update. Biomolecules 2023; 13:1716. [PMID: 38136587 PMCID: PMC10741624 DOI: 10.3390/biom13121716] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Revised: 11/17/2023] [Accepted: 11/20/2023] [Indexed: 12/24/2023] Open
Abstract
Multicopper oxidases (MCOs) share a common catalytic mechanism of activation by oxygen and cupredoxin-like folding, along with some common structural determinants. Laccases constitute the largest group of MCOs, with fungal laccases having the greatest biotechnological applicability due to their superior ability to oxidize a wide range of aromatic compounds and lignin, which is enhanced in the presence of redox mediators. The adaptation of these versatile enzymes to specific application processes can be achieved through the directed evolution of the recombinant enzymes. On the other hand, their substrate versatility and the low sequence homology among laccases make their exact classification difficult. Many of the ever-increasing amounts of MCO entries from fungal genomes are automatically (and often wrongly) annotated as laccases. In a recent comparative genomic study of 52 basidiomycete fungi, MCO classification was revised based on their phylogeny. The enzymes clustered according to common structural motifs and theoretical activities, revealing three novel groups of laccase-like enzymes. This review provides an overview of the structure, catalytic activity, and oxidative mechanism of fungal laccases and how their biotechnological potential as biocatalysts in industry can be greatly enhanced by protein engineering. Finally, recent information on newly identified MCOs with laccase-like activity is included.
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Affiliation(s)
| | - Susana Camarero
- Margarita Salas Center for Biological Research, Consejo Superior de Investigaciones Científicas (CSIC), 28040 Madrid, Spain;
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4
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De Vitis V, Cannazza P, Mattio L, Romano D, Pinto A, Molinari F, Laurenzi T, Eberini I, Contente ML. Caulobacter segnis Dioxygenase CsO2: A Practical Biocatalyst for Stilbenoid Ozonolysis. Chembiochem 2023; 24:e202300477. [PMID: 37490046 DOI: 10.1002/cbic.202300477] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2023] [Revised: 07/25/2023] [Accepted: 07/25/2023] [Indexed: 07/26/2023]
Abstract
Ozonolysis is a useful as well as dangerous reaction for performing alkene cleavage. On the other hand, enzymes are considered a more sustainable and safer alternative. Among them, Caulobacter segnis dioxygenase (CsO2) known so far for its ability to catalyze the coenzyme-free oxidation of vinylguaiacol into vanillin, was selected and its substrate scope evaluated towards diverse natural and synthetic stilbenoids. Under optimized conditions, CsO2 catalyzed the oxidative cleavage of the C=C double bonds of various trans-stilbenes, providing that a hydroxyl moiety was necessary in para-position of the phenyl group (e. g., resveratrol and its derivatives) for the reaction to take place, which was confirmed by modelling studies. The reactions occurred rapidly (0.5-3 h) with high conversions (95-99 %) and without formation of by-products. The resveratrol biotransformation was carried out on 50-mL scale thus confirming the feasibility of the biocatalytic system as a preparative method.
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Affiliation(s)
- Valerio De Vitis
- Department of Food, Environmental and Nutritional Sciences (DeFENS), University of Milan, via Celoria, 2, 20133, Milan, Italy
| | - Pietro Cannazza
- Department of Food, Environmental and Nutritional Sciences (DeFENS), University of Milan, via Celoria, 2, 20133, Milan, Italy
| | - Luce Mattio
- Department of Food, Environmental and Nutritional Sciences (DeFENS), University of Milan, via Celoria, 2, 20133, Milan, Italy
| | - Diego Romano
- Department of Food, Environmental and Nutritional Sciences (DeFENS), University of Milan, via Celoria, 2, 20133, Milan, Italy
| | - Andrea Pinto
- Department of Food, Environmental and Nutritional Sciences (DeFENS), University of Milan, via Celoria, 2, 20133, Milan, Italy
| | - Francesco Molinari
- Department of Food, Environmental and Nutritional Sciences (DeFENS), University of Milan, via Celoria, 2, 20133, Milan, Italy
| | - Tommaso Laurenzi
- Department of Pharmacological and Biomolecular Sciences "Rodolfo Paoletti", University of Milan, Via Balzaretti, 9, 20133, Milano, Italy
| | - Ivano Eberini
- Department of Pharmacological and Biomolecular Sciences "Rodolfo Paoletti", University of Milan, Via Balzaretti, 9, 20133, Milano, Italy
| | - Martina L Contente
- Department of Food, Environmental and Nutritional Sciences (DeFENS), University of Milan, via Celoria, 2, 20133, Milan, Italy
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5
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Jin J, Arciszewski J, Auclair K, Jia Z. Enzymatic polyethylene biorecycling: Confronting challenges and shaping the future. JOURNAL OF HAZARDOUS MATERIALS 2023; 460:132449. [PMID: 37690195 DOI: 10.1016/j.jhazmat.2023.132449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/24/2023] [Revised: 08/25/2023] [Accepted: 08/30/2023] [Indexed: 09/12/2023]
Abstract
Polyethylene (PE) is a widely used plastic known for its resistance to biodegradation, posing a significant environmental challenge. Recent advances have shed light on microorganisms and insects capable of breaking down PE and identified potential PE-degrading enzymes (PEases), hinting at the possibility of PE biorecycling. Research on enzymatic PE degradation is still in its early stages, especially compared to the progress made with polyethylene terephthalate (PET). While PET hydrolases have been extensively studied and engineered for improved performance, even the products of PEases remain mostly undefined. This Perspective analyzes the current state of enzymatic PE degradation research, highlighting obstacles in the search for bona fide PEases and suggesting areas for future exploration. A critical challenge impeding progress in this field stems from the inert nature of the C-C and C-H bonds of PE. Furthermore, breaking down PE into small molecules using only one monofunctional enzyme is theoretically impossible. Overcoming these obstacles requires identifying enzymatic pathways, which can be facilitated using emerging technologies like omics, structure-based design, and computer-assisted engineering of enzymes. Understanding the mechanisms underlying PE enzymatic biodegradation is crucial for research progress and for identifying potential solutions to the global plastic pollution crisis.
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Affiliation(s)
- Jin Jin
- Department of Biomedical and Molecular Sciences, Queen's University, 18 Stuart Street, Kingston, ON KL7 3N6, Canada
| | - Jane Arciszewski
- Department of Chemistry, McGill University, 801 Sherbrooke St. West, Montréal QC H3A 0B8, Canada
| | - Karine Auclair
- Department of Chemistry, McGill University, 801 Sherbrooke St. West, Montréal QC H3A 0B8, Canada
| | - Zongchao Jia
- Department of Biomedical and Molecular Sciences, Queen's University, 18 Stuart Street, Kingston, ON KL7 3N6, Canada.
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6
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Tan Z, Li J, Hou J, Gonzalez R. Designing artificial pathways for improving chemical production. Biotechnol Adv 2023; 64:108119. [PMID: 36764336 DOI: 10.1016/j.biotechadv.2023.108119] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 02/01/2023] [Accepted: 02/06/2023] [Indexed: 02/11/2023]
Abstract
Metabolic engineering exploits manipulation of catalytic and regulatory elements to improve a specific function of the host cell, often the synthesis of interesting chemicals. Although naturally occurring pathways are significant resources for metabolic engineering, these pathways are frequently inefficient and suffer from a series of inherent drawbacks. Designing artificial pathways in a rational manner provides a promising alternative for chemicals production. However, the entry barrier of designing artificial pathway is relatively high, which requires researchers a comprehensive and deep understanding of physical, chemical and biological principles. On the other hand, the designed artificial pathways frequently suffer from low efficiencies, which impair their further applications in host cells. Here, we illustrate the concept and basic workflow of retrobiosynthesis in designing artificial pathways, as well as the most currently used methods including the knowledge- and computer-based approaches. Then, we discuss how to obtain desired enzymes for novel biochemistries, and how to trim the initially designed artificial pathways for further improving their functionalities. Finally, we summarize the current applications of artificial pathways from feedstocks utilization to various products synthesis, as well as our future perspectives on designing artificial pathways.
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Affiliation(s)
- Zaigao Tan
- State Key Laboratory of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai, China; School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China; Department of Bioengineering, Shanghai Jiao Tong University, Shanghai, China.
| | - Jian Li
- State Key Laboratory of Microbial Metabolism, Shanghai Jiao Tong University, Shanghai, China; School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, China; Department of Bioengineering, Shanghai Jiao Tong University, Shanghai, China
| | - Jin Hou
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Ramon Gonzalez
- Department of Chemical, Biological, and Materials Engineering, University of South Florida, Tampa, FL, USA.
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7
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Rodríguez-Escribano D, Pliego-Magán R, de Salas F, Aza P, Gentili P, Ihalainen P, Levée T, Meyer V, Petit-Conil M, Tapin-Lingua S, Lecourt M, Camarero S. Tailor-made alkaliphilic and thermostable fungal laccases for industrial wood processing. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2022; 15:149. [PMID: 36581887 PMCID: PMC9798632 DOI: 10.1186/s13068-022-02247-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/14/2022] [Accepted: 12/14/2022] [Indexed: 06/17/2023]
Abstract
BACKGROUND During the kraft process to obtain cellulosic pulp from wood, most of the lignin is removed by high-temperature alkaline cooking, released in the black liquors and usually incinerated for energy. However, kraft lignins are a valuable source of phenolic compounds that can be valorized in new bio-based products. The aim of this work is to develop laccases capable of working under the extreme conditions of high temperature and pH, typical of the industrial conversion of wood into kraft pulp and fibreboard, in order to provide extremophilic biocatalysts for depolymerising kraft lignin, and enzyme-assisted technologies for kraft pulp and fibreboard production. RESULTS Through systematic enzyme engineering, combining enzyme-directed evolution and rational design, we changed the optimal pH of the laccase for oxidation of lignin phenols from acidic to basic, enhanced the catalytic activity at alkaline pH and increased the thermal tolerance of the enzyme by accumulating up to eight mutations in the protein sequence. The extremophilic laccase variants show maximum activity at 70 °C and oxidize kraft lignin at pH 10. Their integration into industrial-type processes saves energy and chemicals. As a pre-bleaching stage, the enzymes promote kraft pulp bleachability and significantly reduce the need for chlorine dioxide compared to the industrial sequence. Their application in wood chips during fibreboard production, facilitates the defibering stage, with less energy required. CONCLUSIONS A set of new alkaliphilic and thermophilic fungal laccases has been developed to operate under the extreme conditions of high temperature and pH typical of industrial wood conversion processes. For the first time basidiomycete laccases of high-redox potential show activity on lignin-derived phenols and polymeric lignin at pH 10. Considering the extreme conditions of current industrial processes for kraft pulp and fibreboard production, the new tailor-made laccases constitute a step forward towards turning kraft pulp mills into biorefineries. Their use as biocatalysts in the wood conversion sector is expected to support the development of more environmentally sound and efficient processes, and more sustainable products.
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Affiliation(s)
| | - Rocío Pliego-Magán
- Centro de Investigaciones Biológicas Margarita Salas, CSIC. Ramiro de Maeztu 9, 28040 Madrid, Spain
| | - Felipe de Salas
- Centro de Investigaciones Biológicas Margarita Salas, CSIC. Ramiro de Maeztu 9, 28040 Madrid, Spain
| | - Pablo Aza
- Centro de Investigaciones Biológicas Margarita Salas, CSIC. Ramiro de Maeztu 9, 28040 Madrid, Spain
| | - Patrizia Gentili
- Sapienza Università Di Roma, Piazzale Aldo Moro, 5, 00185 Rome, RM Italy
| | | | - Thomas Levée
- MetGen Oy, Rakentajantie 26, 20780 Kaarina, Finland
| | - Valérie Meyer
- Centre Technique du Papier (CTP), Domaine Universitaire, 38044 Grenoble Cedex 9, France
| | - Michel Petit-Conil
- Centre Technique du Papier (CTP), Domaine Universitaire, 38044 Grenoble Cedex 9, France
| | | | - Michael Lecourt
- FCBA Institut Technologique, 341 Rue de La Papeterie, 38610 Gières, France
| | - Susana Camarero
- Centro de Investigaciones Biológicas Margarita Salas, CSIC. Ramiro de Maeztu 9, 28040 Madrid, Spain
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8
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Mahuri M, Paul M, Sahu SK, Thatoi H. In silico homology modeling, docking and sequence analysis of some bacterial laccases to unravel enzymatic specificity towards lignin biodegradation. J Biomol Struct Dyn 2022:1-19. [PMID: 35838062 DOI: 10.1080/07391102.2022.2096117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Laccase is a delignifying enzyme that belongs to the oxidoreductase family, and it has long been investigated as a pretreatment agent in biofuel production. In this study, amino acid sequences of five bacterial laccases from Bifidobacterium breve, Klebsiella pneumonia, Pseudodesulfovibrio hydrargyri, Pseudomonas aeruginosa and Veillonella rodentium have been retrieved from UniProtKB for sequence alignment, phylogenetic analysis using MEGA 7.0 and 3 D structure prediction by homology modeling in SWISS-MODEL. Multiple sequence alignment between all the bacterial laccase sequences revealed a similar structural fold, although the overall protein sequence varied greatly with the substrate binding sites. Further molecular docking in AutoDock Vina and MD stimulation (MDS) in GROMACS for those modelled enzymes were performed considering both apo and ligand bound structures considering both apo and its ligand bound form. Investigation of molecular interaction utilizing docking of five bacterial laccases with three substrates (ABTS, DMP and Guaiacol) revealed that ABTS with K. pneumoniae laccase had the highest binding energy of -7.00 kcal/mol. In the current MDS investigation, bacterial laccases demonstrated greater binding and substrate energy in the ligand bound complex than in the apo form for ABTS, DMP and Guaiacol. In most cases of bacterial laccase, MDS revealed that DMP bound complex was more stable within an average RMSD value lower than 0.5 nm throughout 100 ns time scale. Thus, in silico studies undertaken in this work will be useful in determining the stable enzyme-substrate complex which further might improve the enzymatic catalysis of bacterial laccases for lignin breakdown and biofuel generation.
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Affiliation(s)
- Monalisa Mahuri
- Department of Biotechnology, Maharaja Sriram Chandra BhanjaDeo University, Baripada, Odisha, India
| | - Manish Paul
- Department of Biotechnology, Maharaja Sriram Chandra BhanjaDeo University, Baripada, Odisha, India
| | - Sumanta Kumar Sahu
- Department of Bioinformatics, Central University of South Bihar, Gaya, India
| | - Hrudayanath Thatoi
- Department of Biotechnology, Maharaja Sriram Chandra BhanjaDeo University, Baripada, Odisha, India
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9
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Dey B, Dutta T. Laccases: thriving the domain of Bio-electrocatalysis. Bioelectrochemistry 2022; 146:108144. [DOI: 10.1016/j.bioelechem.2022.108144] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Revised: 04/21/2022] [Accepted: 04/25/2022] [Indexed: 12/19/2022]
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10
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Warwicker J. The Physical Basis for pH Sensitivity in Biomolecular Structure and Function, With Application to the Spike Protein of SARS-CoV-2. Front Mol Biosci 2022; 9:834011. [PMID: 35252354 PMCID: PMC8894873 DOI: 10.3389/fmolb.2022.834011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2021] [Accepted: 01/19/2022] [Indexed: 11/24/2022] Open
Abstract
Since pH sensitivity has a fundamental role in biology, much effort has been committed to establishing physical models to rationalize and predict pH dependence from molecular structures. Two of the key challenges are to accurately calculate ionizable group solvation and hydration and then to apply this modeling to all conformations relevant to the process in question. Explicit solvent methods coupled to molecular dynamics simulation are increasingly complementing lower resolution implicit solvent techniques, but equally, the scale of biological data acquisition leaves a role for high-throughput modeling. Additionally, determination of ranges of structures for a system allows sampling of key stages in solvation. In a review of the area, it is emphasized that pH sensors in biology beyond the most obvious candidate (histidine side chain, with an unshifted pK a near neutral pH) should be considered; that modeling can benefit from other concepts in bioinformatics, in particular modulation of interactions and function in families of homologs; and that it can also be beneficial to incorporate as many experimental structures as possible, to mitigate against small variations in conformation and to analyze larger, functional, conformational changes. These aspects are then demonstrated with new work on the spike protein of SARS-CoV-2, looking at the pH dependence of variants, including prediction of a change in the balance of locked, closed, and open forms at neutral pH for the Omicron variant spike protein.
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Affiliation(s)
- Jim Warwicker
- School of Biological Sciences, Faculty of Biology, Medicine and Health, Manchester Institute of Biotechnology, University of Manchester, Manchester, United Kingdom
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11
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Cajnko MM, Oblak J, Grilc M, Likozar B. Enzymatic bioconversion process of lignin: mechanisms, reactions and kinetics. BIORESOURCE TECHNOLOGY 2021; 340:125655. [PMID: 34388661 DOI: 10.1016/j.biortech.2021.125655] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 07/20/2021] [Accepted: 07/22/2021] [Indexed: 06/13/2023]
Abstract
Lignin is a wasted renewable source of biomass-derived value-added chemicals. However, due to its material resistance to degradation, it remains highly underutilized. In order to develop new, catalysed and more environment friendly reaction processes for lignin valorization, science has turned a selective concentrated attention to microbial enzymes. This present work looks at the enzymes involved with the main reference focus on the different elementary mechanisms of action/conversion rate kinetics. Pathways, like with laccases/peroxidases, employ radicals, which more readily result in polymerization than de-polymerization. The β-etherase system interaction of proteins targets β-O-4 ether covalent bond, which targets lower molecular weight product species. Enzymatic activity is influenced by a wide variety of different factors which need to be considered in order to obtain the best functionality and synthesis yields.
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Affiliation(s)
- Miša Mojca Cajnko
- Department of Catalysis and Chemical Reaction Engineering, National Institute of Chemistry, NIC, Hajdrihova, 19, SI-1001 Ljubljana, Slovenia
| | - Jošt Oblak
- Department of Catalysis and Chemical Reaction Engineering, National Institute of Chemistry, NIC, Hajdrihova, 19, SI-1001 Ljubljana, Slovenia
| | - Miha Grilc
- Department of Catalysis and Chemical Reaction Engineering, National Institute of Chemistry, NIC, Hajdrihova, 19, SI-1001 Ljubljana, Slovenia
| | - Blaž Likozar
- Department of Catalysis and Chemical Reaction Engineering, National Institute of Chemistry, NIC, Hajdrihova, 19, SI-1001 Ljubljana, Slovenia.
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12
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Aza P, Molpeceres G, Ruiz-Dueñas FJ, Camarero S. Heterologous Expression, Engineering and Characterization of a Novel Laccase of Agrocybe pediades with Promising Properties as Biocatalyst. J Fungi (Basel) 2021; 7:359. [PMID: 34064437 PMCID: PMC8147764 DOI: 10.3390/jof7050359] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 04/23/2021] [Accepted: 04/29/2021] [Indexed: 11/16/2022] Open
Abstract
Agaricomycetes fungi responsible for decay of wood and other lignocellulosic substrates constitute a valuable source of lignin-degrading enzymes. Among these enzymes, laccases (multi-copper oxidases) present remarkable biotechnological potential as environmentally friendly biocatalysts able to oxidize a wide range of aromatic compounds using oxygen as the only requirement. Laccases from saprotrophic Agaricales species have been much less studied than laccases from Polyporales, despite the fact that the former fungi are excellent sources of laccases. Here, the gene of a novel laccase of Agrocybe pediades, that is secreted by the fungus during lignocellulose degradation, was synthesised de novo and expressed in Saccharomyces cerevisiae using an improved signal peptide previously obtained and enzyme directed evolution. The characterization of the new laccase variants provided new insights on the contribution of different amino acid residues to modulate laccase production, catalytic activity or optimal pH. The selected double-mutated variant also showed interesting properties as a biocatalyst, such as the ability to oxidise a wide range of substrates, including high-redox potential mediators and recalcitrant organic dyes, improved activity at neutral pH and high tolerance to inhibitors. Finally, we demonstrate the existence of three N-glycosylation sites in the laccase and their distinct effect on the secretion or catalytic activity of the enzyme.
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Affiliation(s)
| | | | | | - Susana Camarero
- Centro de Investigaciones Biológicas Margarita Salas, CSIC. Ramiro de Maeztu 9, 28040 Madrid, Spain; (P.A.); (G.M.); (F.J.R.-D.)
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13
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Ramanavicius S, Ramanavicius A. Charge Transfer and Biocompatibility Aspects in Conducting Polymer-Based Enzymatic Biosensors and Biofuel Cells. NANOMATERIALS (BASEL, SWITZERLAND) 2021; 11:371. [PMID: 33540587 PMCID: PMC7912793 DOI: 10.3390/nano11020371] [Citation(s) in RCA: 72] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/31/2020] [Revised: 01/23/2021] [Accepted: 01/24/2021] [Indexed: 02/06/2023]
Abstract
Charge transfer (CT) is a very important issue in the design of biosensors and biofuel cells. Some nanomaterials can be applied to facilitate the CT in these bioelectronics-based devices. In this review, we overview some CT mechanisms and/or pathways that are the most frequently established between redox enzymes and electrodes. Facilitation of indirect CT by the application of some nanomaterials is frequently applied in electrochemical enzymatic biosensors and biofuel cells. More sophisticated and still rather rarely observed is direct charge transfer (DCT), which is often addressed as direct electron transfer (DET), therefore, DCT/DET is also targeted and discussed in this review. The application of conducting polymers (CPs) for the immobilization of enzymes and facilitation of charge transfer during the design of biosensors and biofuel cells are overviewed. Significant attention is paid to various ways of synthesis and application of conducting polymers such as polyaniline, polypyrrole, polythiophene poly(3,4-ethylenedioxythiophene). Some DCT/DET mechanisms in CP-based sensors and biosensors are discussed, taking into account that not only charge transfer via electrons, but also charge transfer via holes can play a crucial role in the design of bioelectronics-based devices. Biocompatibility aspects of CPs, which provides important advantages essential for implantable bioelectronics, are discussed.
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Affiliation(s)
- Simonas Ramanavicius
- Department of Physical Chemistry, Faculty of Chemistry and Geosciences, Institute of Chemistry, Vilnius University, Naugarduko 24, LT-03225 Vilnius, Lithuania
| | - Arunas Ramanavicius
- Department of Physical Chemistry, Faculty of Chemistry and Geosciences, Institute of Chemistry, Vilnius University, Naugarduko 24, LT-03225 Vilnius, Lithuania
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14
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Li C, Zhang R, Wang J, Wilson LM, Yan Y. Protein Engineering for Improving and Diversifying Natural Product Biosynthesis. Trends Biotechnol 2020; 38:729-744. [PMID: 31954530 PMCID: PMC7274900 DOI: 10.1016/j.tibtech.2019.12.008] [Citation(s) in RCA: 84] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Revised: 11/26/2019] [Accepted: 12/06/2019] [Indexed: 01/26/2023]
Abstract
Proteins found in nature have traditionally been the most frequently used biocatalysts to produce numerous natural products ranging from commodity chemicals to pharmaceuticals. Protein engineering has emerged as a powerful biotechnological toolbox in the development of metabolic engineering, particularly for the biosynthesis of natural products. Recently, protein engineering has become a favored method to improve enzymatic activity, increase enzyme stability, and expand product spectra in natural product biosynthesis. This review summarizes recent advances and typical strategies in protein engineering, highlighting the paramount role of protein engineering in improving and diversifying the biosynthesis of natural products. Future prospects and research directions are also discussed.
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Affiliation(s)
- Chenyi Li
- School of Chemical, Materials, and Biomedical Engineering, College of Engineering, The University of Georgia, Athens, GA 30602, USA
| | - Ruihua Zhang
- School of Chemical, Materials, and Biomedical Engineering, College of Engineering, The University of Georgia, Athens, GA 30602, USA
| | - Jian Wang
- School of Chemical, Materials, and Biomedical Engineering, College of Engineering, The University of Georgia, Athens, GA 30602, USA
| | - Lauren Marie Wilson
- School of Chemical, Materials, and Biomedical Engineering, College of Engineering, The University of Georgia, Athens, GA 30602, USA
| | - Yajun Yan
- School of Chemical, Materials, and Biomedical Engineering, College of Engineering, The University of Georgia, Athens, GA 30602, USA.
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15
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Gräff M, Buchholz PCF, Le Roes‐Hill M, Pleiss J. Multicopper oxidases: modular structure, sequence space, and evolutionary relationships. Proteins 2020; 88:1329-1339. [DOI: 10.1002/prot.25952] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 04/22/2020] [Accepted: 05/16/2020] [Indexed: 12/13/2022]
Affiliation(s)
- Maike Gräff
- Institute of Biochemistry and Technical Biochemistry, University of Stuttgart Stuttgart Germany
| | - Patrick C. F. Buchholz
- Institute of Biochemistry and Technical Biochemistry, University of Stuttgart Stuttgart Germany
| | - Marilize Le Roes‐Hill
- Applied Microbial and Health Biotechnology Institute, Cape Peninsula University of Technology Bellville South Africa
| | - Jürgen Pleiss
- Institute of Biochemistry and Technical Biochemistry, University of Stuttgart Stuttgart Germany
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16
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Ligninolytic Enzymes Mediated Ligninolysis: An Untapped Biocatalytic Potential to Deconstruct Lignocellulosic Molecules in a Sustainable Manner. Catal Letters 2020. [DOI: 10.1007/s10562-019-03096-9] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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17
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Abstract
There is a high number of well characterized, commercially available laccases with different redox potentials and low substrate specificity, which in turn makes them attractive for a vast array of biotechnological applications. Laccases operate as batteries, storing electrons from individual substrate oxidation reactions to reduce molecular oxygen, releasing water as the only by-product. Due to society’s increasing environmental awareness and the global intensification of bio-based economies, the biotechnological industry is also expanding. Enzymes such as laccases are seen as a better alternative for use in the wood, paper, textile, and food industries, and they are being applied as biocatalysts, biosensors, and biofuel cells. Almost 140 years from the first description of laccase, industrial implementations of these enzymes still remain scarce in comparison to their potential, which is mostly due to high production costs and the limited control of the enzymatic reaction side product(s). This review summarizes the laccase applications in the last decade, focusing on the published patents during this period.
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18
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Yin Q, Zhou G, Peng C, Zhang Y, Kües U, Liu J, Xiao Y, Fang Z. The first fungal laccase with an alkaline pH optimum obtained by directed evolution and its application in indigo dye decolorization. AMB Express 2019; 9:151. [PMID: 31535295 PMCID: PMC6751238 DOI: 10.1186/s13568-019-0878-2] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Accepted: 09/09/2019] [Indexed: 11/10/2022] Open
Abstract
Engineering of fungal laccases with optimum catalytic activity at alkaline pH has been a long-lasting challenge. In this study, a mutant library containing 3000 clones was obtained by error-prone PCR to adapt the optimum pH of a fungal laccase Lcc9 from the basidiomycete Coprinopsis cinerea. After three rounds of functional screening, a mutant with three amino acid changes (E116K, N229D, I393T) named PIE5 was selected. PIE5 showed an optimum pH of 8.5 and 8.0 against guaiacol and 2,6-DMP when expressed in Pichia pastoris, representing the first fungal laccase that possesses an optimum pH at an alkaline condition. Site directed mutagenesis disclosed that N229D contributed the most to the optimum pH increment. A single N229D mutation caused an increase in optimum pH by 1.5 units. When used in indigo dye decolorization, PIE5 efficiently decolorized 87.1 ± 1.1% and 90.9 ± 0.3% indigo dye at the optimum conditions of pH 7.0-7.5 and 60 °C, and with either methyl 3,5-dimethoxy-4-hydroxybenzoate or 2,2'-azino-bis(3-ethylbenzothazoline-6-sulfonate) as the mediator. In comparison, the commercially available fungal laccase TvLac from Trametes villosa decolorized 84.3 ± 1.8% of indigo dye under its optimum conditions (opt. pH 5.0 and 60 °C). The properties of an alkaline-dependent activity and the high indigo dye decolorization ability (1.3-fold better than the parental Lcc9) make the new fungal laccase PIE5 an alternative for specific industrial applications.
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Affiliation(s)
- Qiang Yin
- School of Life Sciences, Anhui University, Hefei, 230601, China
- Anhui Key Laboratory of Modern Biomanufacturing, Hefei, 230601, China
| | - Gang Zhou
- School of Life Sciences, Anhui University, Hefei, 230601, China
- Anhui Key Laboratory of Modern Biomanufacturing, Hefei, 230601, China
| | - Can Peng
- School of Life Sciences, Anhui University, Hefei, 230601, China
- Anhui Key Laboratory of Modern Biomanufacturing, Hefei, 230601, China
| | - Yinliang Zhang
- School of Life Sciences, Anhui University, Hefei, 230601, China
- Anhui Key Laboratory of Modern Biomanufacturing, Hefei, 230601, China
| | - Ursula Kües
- Molecular Wood Biotechnology and Technical Mycology, Büsgen-Institute, University of Goettingen, Büsgenweg 2, 37077, Göttingen, Germany
- Goettingen Center for Molecular Biosciences (GZMB), University of Goettingen, 37077, Göttingen, Germany
| | - Juanjuan Liu
- School of Life Sciences, Anhui University, Hefei, 230601, China
- Anhui Key Laboratory of Modern Biomanufacturing, Hefei, 230601, China
| | - Yazhong Xiao
- School of Life Sciences, Anhui University, Hefei, 230601, China.
- Anhui Key Laboratory of Modern Biomanufacturing, Hefei, 230601, China.
| | - Zemin Fang
- School of Life Sciences, Anhui University, Hefei, 230601, China.
- Anhui Key Laboratory of Modern Biomanufacturing, Hefei, 230601, China.
- Institute of Physical Science and Information Technology, Anhui University, Hefei, 230601, China.
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19
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Xie C, Gong W, Zhu Z, Zhou Y, Yan L, Hu Z, Ai L, Peng Y. Mapping the Secretome and Its N-Linked Glycosylation of Pleurotus eryngii and Pleurotus ostreatus Grown on Hemp Stalks. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2019; 67:5486-5495. [PMID: 31012315 DOI: 10.1021/acs.jafc.9b00061] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Our previous research showed that Pleurotus eryngii and Pleurotus ostreatus were effective fungi for pretreatment of industrial hemp stalks to improve enzymatic saccharification. The secretomes of these two fungi were analyzed to search for the effective enzyme cocktails degrading hemp lignin during the pretreatment process. In total, 169 and 155 proteins were identified in Pleurotus eryngii and Pleurotus ostreatus, respectively, and 50% of the proteins involved in lignocellulose degradation were CAZymes. Because most of the extracellular proteins secreted by fungi are glycosylated proteins, the N-linked glycosylation of enzymes could be mapped. In total, 27 and 24 N-glycosylated peptides were detected in Pleurotus eryngii and Pleurotus ostreatus secretomes, respectively. N-Glycosylated peptides of laccase, GH92, exoglucanase, phenol oxidase, α-galactosidase, carboxylic ester hydrolase, and pectin lyase were identified. Deglycosylation could decrease enzymatic saccharification of hemp stalks. The activities of laccase, α-galactosidase, and phenol oxidase and the thermal stability of laccase were reduced after deglycosylation.
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Affiliation(s)
- Chunliang Xie
- Institute of Bast Fiber Crops , Chinese Academy of Agricultural Sciences , Changsha 410205 , China
| | - Wenbing Gong
- Institute of Bast Fiber Crops , Chinese Academy of Agricultural Sciences , Changsha 410205 , China
| | - Zuohua Zhu
- Institute of Bast Fiber Crops , Chinese Academy of Agricultural Sciences , Changsha 410205 , China
| | - Yingjun Zhou
- Institute of Bast Fiber Crops , Chinese Academy of Agricultural Sciences , Changsha 410205 , China
| | - Li Yan
- Institute of Bast Fiber Crops , Chinese Academy of Agricultural Sciences , Changsha 410205 , China
| | - Zhenxiu Hu
- Institute of Bast Fiber Crops , Chinese Academy of Agricultural Sciences , Changsha 410205 , China
| | - Lianzhong Ai
- Institute of Bast Fiber Crops , Chinese Academy of Agricultural Sciences , Changsha 410205 , China
- Shanghai Engineering Research Center of Food Microbiology, School of Medical Instrument and Food Engineering , University of Shanghai for Science and Technology , Shanghai 200093 , China
| | - Yuande Peng
- Institute of Bast Fiber Crops , Chinese Academy of Agricultural Sciences , Changsha 410205 , China
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20
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Karnaouri A, Antonopoulou I, Zerva A, Dimarogona M, Topakas E, Rova U, Christakopoulos P. Thermophilic enzyme systems for efficient conversion of lignocellulose to valuable products: Structural insights and future perspectives for esterases and oxidative catalysts. BIORESOURCE TECHNOLOGY 2019; 279:362-372. [PMID: 30685134 DOI: 10.1016/j.biortech.2019.01.062] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Revised: 01/12/2019] [Accepted: 01/15/2019] [Indexed: 06/09/2023]
Abstract
Thermophilic enzyme systems are of major importance nowadays in all industrial processes due to their great performance at elevated temperatures. In the present review, an overview of the current knowledge on the properties of thermophilic and thermotolerant carbohydrate esterases and oxidative enzymes with great thermostability is provided, with respect to their potential use in biotechnological applications. A special focus is given to the lytic polysaccharide monooxygenases that are able to oxidatively cleave lignocellulose through the use of oxygen or hydrogen peroxide as co-substrate and a reducing agent as electron donor. Structural characteristics of the enzymes, including active site conformation and surface properties are discussed and correlated with their substrate specificity and thermostability properties.
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Affiliation(s)
- Anthi Karnaouri
- Biochemical Process Engineering, Chemical Engineering, Department of Civil, Environmental and Natural Resources Engineering, Luleå University of Technology, Luleå, Sweden.
| | - Io Antonopoulou
- Biochemical Process Engineering, Chemical Engineering, Department of Civil, Environmental and Natural Resources Engineering, Luleå University of Technology, Luleå, Sweden
| | - Anastasia Zerva
- Biotechnology Laboratory, Department of Synthesis and Development of Industrial Processes, School of Chemical Engineering, National Technical University of Athens, Athens, Greece
| | - Maria Dimarogona
- Section of Process and Environmental Engineering, Department of Chemical Engineering, University of Patras, 26504 Rio, Patras, Greece
| | - Evangelos Topakas
- Biotechnology Laboratory, Department of Synthesis and Development of Industrial Processes, School of Chemical Engineering, National Technical University of Athens, Athens, Greece
| | - Ulrika Rova
- Biochemical Process Engineering, Chemical Engineering, Department of Civil, Environmental and Natural Resources Engineering, Luleå University of Technology, Luleå, Sweden
| | - Paul Christakopoulos
- Biochemical Process Engineering, Chemical Engineering, Department of Civil, Environmental and Natural Resources Engineering, Luleå University of Technology, Luleå, Sweden.
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21
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Advances in microbial lignin degradation and its applications. Curr Opin Biotechnol 2019; 56:179-186. [DOI: 10.1016/j.copbio.2018.11.011] [Citation(s) in RCA: 87] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Revised: 11/14/2018] [Accepted: 11/14/2018] [Indexed: 12/29/2022]
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22
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Lopes P, Koschorreck K, Nedergaard Pedersen J, Ferapontov A, Lörcher S, Skov Pedersen J, Urlacher VB, Ferapontova EE. Bacillus Licheniformis
CotA Laccase Mutant: ElectrocatalyticReduction of O
2
from 0.6 V (SHE) at pH 8 and in Seawater. ChemElectroChem 2019. [DOI: 10.1002/celc.201900363] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Paula Lopes
- Interdisciplinary Nanoscience Center, iNANOAarhus University Gustav Wieds Vej 14 8000 Aarhus Denmark
- Current address: Gent University Zwijnaard 126 9052 Belgium
| | - Katja Koschorreck
- Institute of BiochemistryHeinrich-Heine University Düsseldorf Universitätsstrasse 1 40225 Düsseldorf Germany
| | | | | | - Samuel Lörcher
- Interdisciplinary Nanoscience Center, iNANOAarhus University Gustav Wieds Vej 14 8000 Aarhus Denmark
- Current address: Universitaet Basel 4056 Basel Switzerland
| | - Jan Skov Pedersen
- Interdisciplinary Nanoscience Center, iNANOAarhus University Gustav Wieds Vej 14 8000 Aarhus Denmark
- Department of ChemistryAarhus University 8000 Aarhus Denmark
| | - Vlada B. Urlacher
- Institute of BiochemistryHeinrich-Heine University Düsseldorf Universitätsstrasse 1 40225 Düsseldorf Germany
| | - Elena E. Ferapontova
- Interdisciplinary Nanoscience Center, iNANOAarhus University Gustav Wieds Vej 14 8000 Aarhus Denmark
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23
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Challenges for successful implantation of biofuel cells. Bioelectrochemistry 2018; 124:57-72. [DOI: 10.1016/j.bioelechem.2018.05.011] [Citation(s) in RCA: 121] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2017] [Revised: 05/11/2018] [Accepted: 05/25/2018] [Indexed: 01/09/2023]
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24
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Directed Evolution of a Homodimeric Laccase from Cerrena unicolor BBP6 by Random Mutagenesis and In Vivo Assembly. Int J Mol Sci 2018; 19:ijms19102989. [PMID: 30274366 PMCID: PMC6213006 DOI: 10.3390/ijms19102989] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 09/19/2018] [Accepted: 09/27/2018] [Indexed: 11/21/2022] Open
Abstract
Laccases have great potential for industrial applications due to their green catalytic properties and broad substrate specificities, and various studies have attempted to improve the catalytic performance of these enzymes. Here, to the best of our knowledge, we firstly report the directed evolution of a homodimeric laccase from Cerrena unicolor BBP6 fused with α-factor prepro-leader that was engineered through random mutagenesis followed by in vivo assembly in Saccharomyces cerevisiae. Three evolved fusion variants selected from ~3500 clones presented 31- to 37-fold increases in total laccase activity, with better thermostability and broader pH profiles. The evolved α-factor prepro-leader enhanced laccase expression levels by up to 2.4-fold. Protein model analysis of these variants reveals that the beneficial mutations have influences on protein pKa shift, subunit interaction, substrate entrance, and C-terminal function.
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25
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Kwiatos N, Jędrzejczak-Krzepkowska M, Strzelecki B, Bielecki S. Improvement of efficiency of brown coal biosolubilization by novel recombinant Fusarium oxysporum laccase. AMB Express 2018; 8:133. [PMID: 30136100 PMCID: PMC6104410 DOI: 10.1186/s13568-018-0669-1] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Accepted: 08/17/2018] [Indexed: 11/10/2022] Open
Abstract
Clean coal technologies (e.g. coal biosolubilization) are of essential value, especially in Europe, where coal is the national wealth and other energy sources like crude oil are not available. Fusarium oxysporum LOCK 1134, the strain isolated from brown coal, efficiently biosolubilizes lignite. The obtained liquefied products contain 50% less sulfur and over 99% less mercury than the crude coal. Moreover, the liquefied coal can be modified further by laccase. In this study F. oxysporum laccase was expressed in Pichia pastoris for the first time and was assessed as an additional agent for coal degradation. The novel laccase contributes to humic and fulvic acids release from liquefied coal due to introduction of oxygen into coal structure. The effect is increased when a natural redox mediator, sinapic acid, is present in the reaction mixture-up to 30% and 80% respectively. Humic acids obtained by biological process are environmentally friendly fertilizers that may have stimulating effects on crop growth.
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