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Sun Z, You Y, Xu H, You Y, He W, Wang Z, Li A, Xia Y. Food-Grade Expression of Two Laccases in Pichia pastoris and Study on Their Enzymatic Degradation Characteristics for Mycotoxins. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2024. [PMID: 38600054 DOI: 10.1021/acs.jafc.4c00521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2024]
Abstract
Mycotoxin contamination poses substantial health risks to humans and animals. In this study, the two laccases PpLac1 and AoLac2 from Pleurotus pulmonarius and Aspergillus oryzae were selected and heterologously expressed in Pichia pastoris in a food-grade manner to detoxify aflatoxin B1 (AFB1), zearalenone (ZEN), and deoxynivalenol (DON). Both laccases exhibited degradation activity toward these three mycotoxins, while the efficiency of these for DON was relatively low. Therefore, molecular docking between these laccases and DON was conducted to analyze their potential interaction mechanisms. Furthermore, the degradation conditions of AFB1 and ZEN by the two laccases were optimized, and the optimal degradation rates for AFB1 and ZEN by PpLac1 reached 78.51 and 78.90%, while those for AFB1 and ZEN by AoLac2 reached 72.27 and 80.60%, respectively. The laccases PpLac1 and AoLac2 successfully transformed AFB1 and ZEN into the compounds AFQ1 and 15-OH-ZEN, which were 90 and 98% less toxic than the original compounds, respectively. Moreover, the culture supernatants demonstrated effective mycotoxin degradation results for AFB1 and ZEN in contaminated feed samples. The residual levels of AFB1 and ZEN in all samples ranged from 6.61 to 8.72 μg/kg and 3.44 to 98.15 μg/kg, respectively, and these levels were below the limit set by the European Union standards. All of the results in this study indicated that the two laccases have excellent application potential in the feed industry.
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Affiliation(s)
- Zhen Sun
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi 214122, China
| | - Yingxin You
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi 214122, China
| | - Huidong Xu
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi 214122, China
| | - Yang You
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi 214122, China
| | - Wenjing He
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi 214122, China
| | - Zhouping Wang
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi 214122, China
| | - Aitao Li
- School of Life Sciences, Hubei University, Wuhan 430062, China
| | - Yu Xia
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, Wuxi 214122, China
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Ali M, Bhardwaj P, Ishqi HM, Shahid M, Islam A. Laccase Engineering: Redox Potential Is Not the Only Activity-Determining Feature in the Metalloproteins. Molecules 2023; 28:6209. [PMID: 37687038 PMCID: PMC10488915 DOI: 10.3390/molecules28176209] [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: 04/09/2023] [Revised: 08/02/2023] [Accepted: 08/08/2023] [Indexed: 09/10/2023] Open
Abstract
Laccase, one of the metalloproteins, belongs to the multicopper oxidase family. It oxidizes a wide range of substrates and generates water as a sole by-product. The engineering of laccase is important to broaden their industrial and environmental applications. The general assumption is that the low redox potential of laccases is the principal obstacle, as evidenced by their low activity towards certain substrates. Therefore, the primary goal of engineering laccases is to improve their oxidation capability, thereby increasing their redox potential. Even though some of the determinants of laccase are known, it is still not entirely clear how to enhance its redox potential. However, the laccase active site has additional characteristics that regulate the enzymes' activity and specificity. These include the electrostatic and hydrophobic environment of the substrate binding pocket, the steric effect at the substrate binding site, and the orientation of the binding substrate with respect to the T1 site of the laccase. In this review, these features of the substrate binding site will be discussed to highlight their importance as a target for future laccase engineering.
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Affiliation(s)
- Misha Ali
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi 110025, India; (M.A.); (P.B.)
| | - Priyanka Bhardwaj
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi 110025, India; (M.A.); (P.B.)
| | - Hassan Mubarak Ishqi
- Department of Surgery and Sylvester Comprehensive Cancer Center, Miller School of Medicine, Miami, FL 33136, USA;
| | - Mohammad Shahid
- Department of Basic Medical Sciences, College of Medicine, Prince Sattam Bin Abdulaziz University, Al-Kharj 16273, Saudi Arabia
| | - Asimul Islam
- Centre for Interdisciplinary Research in Basic Sciences, Jamia Millia Islamia, New Delhi 110025, India; (M.A.); (P.B.)
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Liao J, Wei X, Tao K, Deng G, Shu J, Qiao Q, Chen G, Wei Z, Fan M, Saud S, Fahad S, Chen S. Phenoloxidases: catechol oxidase - the temporary employer and laccase - the rising star of vascular plants. HORTICULTURE RESEARCH 2023; 10:uhad102. [PMID: 37786731 PMCID: PMC10541563 DOI: 10.1093/hr/uhad102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/04/2023] [Revised: 05/16/2023] [Accepted: 05/05/2023] [Indexed: 10/04/2023]
Abstract
Phenolics are vital for the adaptation of plants to terrestrial habitats and for species diversity. Phenoloxidases (catechol oxidases, COs, and laccases, LACs) are responsible for the oxidation and polymerization of phenolics. However, their origin, evolution, and differential roles during plant development and land colonization are unclear. We performed the phylogeny, domain, amino acids, compositional biases, and intron analyses to clarify the origin and evolution of COs and LACs, and analysed the structure, selective pressure, and chloroplast targeting to understand the species-dependent distribution of COs. We found that Streptophyta COs were not homologous to the Chlorophyta tyrosinases (TYRs), and might have been acquired by horizontal gene transfer from bacteria. COs expanded in bryophytes. Structural-functionality and selective pressure were partially responsible for the species-dependent retention of COs in embryophytes. LACs emerged in Zygnemaphyceae, having evolved from ascorbate oxidases (AAOs), and prevailed in the vascular plants and strongly expanded in seed plants. COs and LACs coevolved with the phenolic metabolism pathway genes. These results suggested that TYRs and AAOs were the first-stage phenoloxidases in Chlorophyta. COs might be the second key for the early land colonization. LACs were the third one (dominating in the vascular plants) and might be advantageous for diversified phenol substrates and the erect growth of plants. This work provided new insights into how phenoloxidases evolved and were devoted to plant evolution.
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Affiliation(s)
- Jugou Liao
- School of Ecology and Environmental Sciences, Yunnan University; Biocontrol Engineering Research Center of Crop Diseases & Pests, Yunnan Province, Kunming 650091, China
| | - Xuemei Wei
- School of Engineering, Dali University, Dali, Yunnan Province, 671003, China
| | - Keliang Tao
- School of Life Science, Yunnan University, Yunnan Province, Kunming 650091, China
| | - Gang Deng
- College of Horticulture and Landscape, Yunnan Agricultural University, Yunnan Province, Kunming 650091, China
| | - Jie Shu
- School of Life Science, Yunnan University, Yunnan Province, Kunming 650091, China
| | - Qin Qiao
- College of Horticulture and Landscape, Yunnan Agricultural University, Yunnan Province, Kunming 650091, China
| | - Gonglin Chen
- School of Ecology and Environmental Sciences, Yunnan University; Biocontrol Engineering Research Center of Crop Diseases & Pests, Yunnan Province, Kunming 650091, China
| | - Zhuo Wei
- School of Ecology and Environmental Sciences, Yunnan University; Biocontrol Engineering Research Center of Crop Diseases & Pests, Yunnan Province, Kunming 650091, China
| | - Meihui Fan
- School of Ecology and Environmental Sciences, Yunnan University; Biocontrol Engineering Research Center of Crop Diseases & Pests, Yunnan Province, Kunming 650091, China
| | - Shah Saud
- College of Life Science, Linyi University, Linyi, Shandong 276000, China
| | - Shah Fahad
- Department of Agronomy, Abdul Wali Khan University Mardan, Khyber Pakhtunkhwa 23200, Pakistan
| | - Suiyun Chen
- School of Ecology and Environmental Sciences, Yunnan University; Biocontrol Engineering Research Center of Crop Diseases & Pests, Yunnan Province, Kunming 650091, China
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Chatterjee A, Puri S, Sharma PK, Deepa PR, Chowdhury S. Nature-inspired Enzyme engineering and sustainable catalysis: biochemical clues from the world of plants and extremophiles. Front Bioeng Biotechnol 2023; 11:1229300. [PMID: 37409164 PMCID: PMC10318364 DOI: 10.3389/fbioe.2023.1229300] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Accepted: 06/12/2023] [Indexed: 07/07/2023] Open
Abstract
The use of enzymes to accelerate chemical reactions for the synthesis of industrially important products is rapidly gaining popularity. Biocatalysis is an environment-friendly approach as it not only uses non-toxic, biodegradable, and renewable raw materials but also helps to reduce waste generation. In this context, enzymes from organisms living in extreme conditions (extremozymes) have been studied extensively and used in industries (food and pharmaceutical), agriculture, and molecular biology, as they are adapted to catalyze reactions withstanding harsh environmental conditions. Enzyme engineering plays a key role in integrating the structure-function insights from reference enzymes and their utilization for developing improvised catalysts. It helps to transform the enzymes to enhance their activity, stability, substrates-specificity, and substrate-versatility by suitably modifying enzyme structure, thereby creating new variants of the enzyme with improved physical and chemical properties. Here, we have illustrated the relatively less-tapped potentials of plant enzymes in general and their sub-class of extremozymes for industrial applications. Plants are exposed to a wide range of abiotic and biotic stresses due to their sessile nature, for which they have developed various mechanisms, including the production of stress-response enzymes. While extremozymes from microorganisms have been extensively studied, there are clear indications that plants and algae also produce extremophilic enzymes as their survival strategy, which may find industrial applications. Typical plant enzymes, such as ascorbate peroxidase, papain, carbonic anhydrase, glycoside hydrolases and others have been examined in this review with respect to their stress-tolerant features and further improvement via enzyme engineering. Some rare instances of plant-derived enzymes that point to greater exploration for industrial use have also been presented here. The overall implication is to utilize biochemical clues from the plant-based enzymes for robust, efficient, and substrate/reaction conditions-versatile scaffolds or reference leads for enzyme engineering.
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Affiliation(s)
| | | | | | - P. R. Deepa
- *Correspondence: P. R. Deepa, ; Shibasish Chowdhury,
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Li Y, Song W, Han X, Wang Y, Rao S, Zhang Q, Zhou J, Li J, Liu S, Du G. Recent progress in key lignocellulosic enzymes: Enzyme discovery, molecular modifications, production, and enzymatic biomass saccharification. BIORESOURCE TECHNOLOGY 2022; 363:127986. [PMID: 36126851 DOI: 10.1016/j.biortech.2022.127986] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2022] [Revised: 09/12/2022] [Accepted: 09/13/2022] [Indexed: 05/15/2023]
Abstract
Lignocellulose, the most prevalent biomass on earth, can be enzymatically converted into carbohydrates for bioethanol production and other uses. Among lignocellulosic enzymes, endoglucanase, xylanase, and laccase are the key enzymes, owing to their ability to disrupt the main structure of lignocellulose. Recently, new discovery methods have been established to obtain key lignocellulosic enzymes with excellent enzymatic properties. Molecular modification of enzymes to modulate their thermostability, catalytic activity, and substrate specificity has been performed with protein engineering technology. In addition, the enzyme expression has been effectively improved through expression element screening and host modification, as well as fermentation optimization. Immobilization of enzymes, use of surfactants, synergistic degradation, and optimization of reaction conditions have addressed the inefficiency of enzymatic saccharification. In this review, recent advances in key lignocellulosic enzymes are summarized, along with future prospects for the development of super-engineered strains and integrative technologies for enzymatic biomass saccharification.
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Affiliation(s)
- Yangyang Li
- Science Center for Future Foods, Jiangnan University, Wuxi 214122, China; National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, Wuxi 214122, China; School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi 214122, China
| | - Weiyan Song
- Science Center for Future Foods, Jiangnan University, Wuxi 214122, China; National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, Wuxi 214122, China; School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi 214122, China
| | - Xuyue Han
- Science Center for Future Foods, Jiangnan University, Wuxi 214122, China; National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, Wuxi 214122, China; School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi 214122, China
| | - Yachan Wang
- Science Center for Future Foods, Jiangnan University, Wuxi 214122, China; National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, Wuxi 214122, China; School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi 214122, China
| | - Shengqi Rao
- College of Food Science and Engineering, Yangzhou University, Yangzhou 214122, China
| | - Quan Zhang
- Dalian Research Institute of Petroleum and Petrochemicals, SINOPEC, Dalian 116000, China
| | - Jingwen Zhou
- Science Center for Future Foods, Jiangnan University, Wuxi 214122, China; National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, Wuxi 214122, China; School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi 214122, China; Jiangsu Provisional Research Center for Bioactive Product Processing Technology, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China
| | - Jianghua Li
- Science Center for Future Foods, Jiangnan University, Wuxi 214122, China; National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, Wuxi 214122, China; School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi 214122, China
| | - Song Liu
- Science Center for Future Foods, Jiangnan University, Wuxi 214122, China; National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, Wuxi 214122, China; School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi 214122, China.
| | - Guocheng Du
- Science Center for Future Foods, Jiangnan University, Wuxi 214122, China; National Engineering Research Center for Cereal Fermentation and Food Biomanufacturing, Jiangnan University, Wuxi 214122, China; School of Biotechnology, Jiangnan University, 1800 Lihu Road, Wuxi 214122, China
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Zhan J, Sun H, Dai Z, Zhang Y, Yang X. Loops constructing the substrate-binding site controlled the catalytic efficiency of Thermus thermophilus SG0.5JP17-16 laccase. Biochimie 2022; 200:60-67. [DOI: 10.1016/j.biochi.2022.05.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 04/26/2022] [Accepted: 05/19/2022] [Indexed: 11/02/2022]
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Zhang X, Huang Z, Wang D, Zhang Y, Eser BE, Gu Z, Dai R, Gao R, Guo Z. A new thermophilic extradiol dioxygenase promises biodegradation of catecholic pollutants. JOURNAL OF HAZARDOUS MATERIALS 2022; 422:126860. [PMID: 34399224 DOI: 10.1016/j.jhazmat.2021.126860] [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: 04/10/2021] [Revised: 07/22/2021] [Accepted: 08/06/2021] [Indexed: 06/13/2023]
Abstract
Extradiol dioxygenases (EDOs) catalyze the meta cleavage of catechol into 2-hydroxymuconaldehyde, a critical step in the degradation of aromatic compounds in the environment. In the present work, a novel thermophilic extradiol dioxygenase from Thermomonospora curvata DSM43183 was cloned, expressed, and characterized by phylogenetic and biochemical analyses. This enzyme exhibited excellent thermo-tolerance, displaying optimal activity at 50 °C, remaining >40% activity at 70 °C. Structural modeling and molecular docking demonstrated that both active center and pocket-construction loops locate at the C-terminal domain. Site-specific mutants D285A, H205V, F301V based on a rational design were obtained to widen the entrance of substrates; resulting in significantly improved catalytic performance for all the 3 mutants. Compared to the wild-type, the mutant D285A showed remarkably improved activities with respect to the 3,4-dihydroxyphenylacetic acid, catechol, and 3-chlorocatechol, by 17.7, 6.9, and 3.7-fold, respectively. The results thus verified the effectiveness of modeling guided design; and confirmed that the C-terminal loop structure indeed plays a decisive role in determining catalytic ring-opening efficiency and substrate specificity of the enzyme. This study provided a novel thermostable dioxygenase with a broad substrate promiscuity for detoxifying environmental pollutants and provided a new thinking for further enzyme engineering of EDOs.
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Affiliation(s)
- Xiaowen Zhang
- Key Laboratory for Molecular Enzymology and Engineering, The Ministry of Education, School of life Science, Jilin University, Changchun 130021, China; Department of Biological and Chemical Engineering, Faculty of Technical Sciences, Aarhus University, Gustav Wieds Vej 10, Aarhus 8000, Denmark
| | - Zihao Huang
- Key Laboratory for Molecular Enzymology and Engineering, The Ministry of Education, School of life Science, Jilin University, Changchun 130021, China
| | - Dan Wang
- Key Laboratory for Molecular Enzymology and Engineering, The Ministry of Education, School of life Science, Jilin University, Changchun 130021, China
| | - Yan Zhang
- Department of Biological and Chemical Engineering, Faculty of Technical Sciences, Aarhus University, Gustav Wieds Vej 10, Aarhus 8000, Denmark
| | - Bekir Engin Eser
- Department of Biological and Chemical Engineering, Faculty of Technical Sciences, Aarhus University, Gustav Wieds Vej 10, Aarhus 8000, Denmark
| | - Zhenyu Gu
- Key Laboratory for Molecular Enzymology and Engineering, The Ministry of Education, School of life Science, Jilin University, Changchun 130021, China
| | - Rongrong Dai
- Department of Biological and Chemical Engineering, Faculty of Technical Sciences, Aarhus University, Gustav Wieds Vej 10, Aarhus 8000, Denmark
| | - Renjun Gao
- Key Laboratory for Molecular Enzymology and Engineering, The Ministry of Education, School of life Science, Jilin University, Changchun 130021, China.
| | - Zheng Guo
- Department of Biological and Chemical Engineering, Faculty of Technical Sciences, Aarhus University, Gustav Wieds Vej 10, Aarhus 8000, Denmark.
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Yan N, Ma H, Yang CX, Liao XR, Guan ZB. Improving the decolorization activity of Bacillus pumilus W3 CotA-laccase to Congo Red by rational modification. Enzyme Microb Technol 2021; 155:109977. [PMID: 34973504 DOI: 10.1016/j.enzmictec.2021.109977] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2021] [Revised: 12/16/2021] [Accepted: 12/18/2021] [Indexed: 11/19/2022]
Abstract
Congo Red (CR) is a typical azo dye with highly toxic and carcinogenic properties. This study aimed to improve the decolorization activity of Bacillus pumilus W3 CotA-laccase for azo dye CR. This work analyzed the interaction between CotA-laccase and CR based on homology modeling and molecular docking. The three amino acids (Gly323, Thr377, Thr418) in the substrate-binding pocket were rationally modified through saturation mutation. Finally, the obtained multi-site mutants T377I/T418G and G323S/T377I/T418G decolorized 76.59% and 59.37% of CR within 24 h at pH 8.0 without a mediator, which were 3.15- and 2.44-fold higher than the wild-type CotA. The catalytic efficiency of the multi-site mutants T377I/T418G and G323S/T377I/T418G to CR were increased by 2.21- and 2.01-fold compared with the wild-type CotA, respectively. The mechanism of activity enhancement of mutants was proposed by structural analysis. This evidence suggests that the mutants T377I/T418G and G323S/T377I/T418G could be used as novel bioremediation tools.
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Affiliation(s)
- Na Yan
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, PR China
| | - Hui Ma
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, PR China
| | - Chun-Xue Yang
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, PR China
| | - Xiang-Ru Liao
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, PR China
| | - Zheng-Bing Guan
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, PR China.
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Ma H, Xu KZ, Wang YJ, Yan N, Liao XR, Guan ZB. Enhancing the decolorization activity of Bacillus pumilus W3 CotA-laccase to Reactive Black 5 by site-saturation mutagenesis. Appl Microbiol Biotechnol 2020; 104:9193-9204. [PMID: 32918582 DOI: 10.1007/s00253-020-10897-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 09/02/2020] [Accepted: 09/07/2020] [Indexed: 12/31/2022]
Abstract
Reactive Black 5 (RB5) is a typical refractory azo dye. Widespread utilization of RB5 has caused a variety of environmental and health problems. The enzymatic degradation of RB5 can be a promising solution due to its superiority as an eco-friendly and cost-competitive process. Bacterial CotA-laccase shows great application prospect to eliminate hazardous dyes from wastewater. However, efficient decolorization of RB5 CotA-laccase generally requires the participation of costly, toxic mediators. In the present study, we modified the amino acids Thr415 and Thr418 near the type 1 copper site and the amino acid Gln442 at the entrance of the substrate-binding pocket of Bacillus pumilus W3 CotA-laccase to boost its RB5 decolorization activity based on molecular docking analysis and site-saturation mutagenesis. Through the strategies, two double site mutants T415D/Q442A and T418K/Q442A obtained demonstrated 43.94 and 52.64% RB5 decolorization rates in the absence of a mediator at pH 10.0, respectively, which were about 3.70- and 4.43-fold higher compared with the wild-type CotA-laccase. Unexpectedly, the catalytic efficiency of the T418K/Q442A to ABTS was enhanced by 5.33-fold compared with the wild-type CotA-laccase. The mechanisms of conferring enhanced activity to the mutants were proposed by structural analysis. In summary, the mutants T415D/Q442A and T418K/Q442A have good application potentials for the biodegradation of RB5. KEY POINTS: • Three amino acids of CotA-laccase were manipulated by site-saturation mutagenesis. • Decolorization rate of two mutants to RB5 was enhanced 3.70- and 4.43-fold, respectively. • The mechanisms of awarding enhanced activity to the mutants were supposed.
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Affiliation(s)
- Hui Ma
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, People's Republic of China
| | - Kai-Zhong Xu
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, People's Republic of China
| | - Ya-Jing Wang
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, People's Republic of China
| | - Na Yan
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, People's Republic of China
| | - Xiang-Ru Liao
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, People's Republic of China
| | - Zheng-Bing Guan
- The Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, 214122, People's Republic of China.
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