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Li L, Liu X, Bai Y, Yao B, Luo H, Tu T. High-Throughput Screening Techniques for the Selection of Thermostable Enzymes. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2024; 72:3833-3845. [PMID: 38285533 DOI: 10.1021/acs.jafc.3c07554] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2024]
Abstract
The acquisition of a thermostable enzyme is an indispensable prerequisite for its successful implementation in industrial applications and the development of novel functionalities. Various protein engineering approaches, including rational design, semirational design, and directed evolution, have been employed to enhance thermostability. However, all of these approaches require sensitive and reliable high-throughput screening (HTS) technologies to efficiently and rapidly identify variants with improved properties. While numerous reviews focus on modification strategies for enhancing enzyme thermostability, there is a dearth of literature reviewing HTS methods specifically aimed at this objective. Herein, we present a comprehensive overview of various HTS methods utilized for modifying enzyme thermostability across different screening platforms. Additionally, we highlight significant recent examples that demonstrate the successful application of these methods. Furthermore, we address the technical challenges associated with HTS technologies used for screening thermostable enzyme variants and discuss valuable perspectives to promote further advancements in this field. This review serves as an authoritative reference source offering theoretical support for selecting appropriate screening strategies tailored to specific enzymes with the aim of improving their thermostability.
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Affiliation(s)
- Lanxue Li
- State Key Laboratory of Animal Nutrition and Feeding, Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Xiaoqing Liu
- Biotechnology Research Institute, Chinese Academy of Agricultural Sciences, Beijing 100081, China
| | - Yingguo Bai
- State Key Laboratory of Animal Nutrition and Feeding, Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Bin Yao
- State Key Laboratory of Animal Nutrition and Feeding, Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Huiying Luo
- State Key Laboratory of Animal Nutrition and Feeding, Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing 100193, China
| | - Tao Tu
- State Key Laboratory of Animal Nutrition and Feeding, Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing 100193, China
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Mo H, Chen X, Tang M, Qu Y, Li Z, Liu W, Yang C, Chen Y, Sun J, Yang H, Du G. Expression of a thermostable glucose-stimulated β-glucosidase from a hot-spring metagenome and its promising application to produce gardenia blue. Bioorg Chem 2024; 143:107036. [PMID: 38141330 DOI: 10.1016/j.bioorg.2023.107036] [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: 10/27/2023] [Revised: 12/06/2023] [Accepted: 12/14/2023] [Indexed: 12/25/2023]
Abstract
This study reports a thermostable glucose-stimulated β-glucosidase, BglY442, from hot-spring metagenomic data that was cloned and expressed in Escherichia coli BL21 (DE3). The molecular mass of recombinant BglY442 was 69.9 kDa and was used in the production of gardenia blue. The recombinant BglY442 showed its maximum activity at pH 6.0 and 75 °C, maintained 50 % activity at 70 °C for 36 h, presented over 90 % activity in a broad pH range and a wide range of pH stability. Moreover, BglY442 exhibited excellent tolerance toward methanol and ethanol. The specific activity of BglY442 was 235 U/mg at pH 6.0 and 75 °C with 10 mM pNPG as substrate. BglY442 activity increased by over fourfold with 2 M glucose or xylose. Specifically, the enzyme kinetics of BglY442 seem to be non-Michaelis-Menten kinetics or atypical kinetics because the Michaelis-Menten saturation kinetics were not observed with pNPG, oNPG or geniposide as substrates. Under optimum conditions, geniposide was dehydrated by BglY442 and reacted with nine amino acids respectively by the one-pot method. Only the Arg or Met derived pigments showed bright blue, and these two pigments had similar ultraviolet absorption spectra. The OD590 nm of GB was detected to be 1.06 after 24 h with the addition of Arg and 1.61 after 36 h with the addition of Met. The intermediate was elucidated and identified as ginipin. Molecular docking analysis indicated that the enzyme had a similar catalytic mechanism to the reported GH1 Bgls. BglY442 exhibited potential for gardenia blue production by the one-pot method. With outstanding thermostability and glucose tolerance, BglY442 should be considered a potential β-glucosidase in biotechnology applications.
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Affiliation(s)
- Haiying Mo
- Yunnan Minzu University, Key Laboratory of Chemistry in Ethnic Medicinal Resources Ministry of Education, Kunming, Yunnan, China
| | - Xin Chen
- Yunnan Minzu University, Key Laboratory of Chemistry in Ethnic Medicinal Resources Ministry of Education, Kunming, Yunnan, China
| | - Manwen Tang
- Yunnan Minzu University, Key Laboratory of Chemistry in Ethnic Medicinal Resources Ministry of Education, Kunming, Yunnan, China
| | - Ying Qu
- Yunnan Minzu University, Key Laboratory of Chemistry in Ethnic Medicinal Resources Ministry of Education, Kunming, Yunnan, China
| | - Zhihao Li
- Yunnan Minzu University, Key Laboratory of Chemistry in Ethnic Medicinal Resources Ministry of Education, Kunming, Yunnan, China
| | - Wang Liu
- Yunnan Minzu University, Key Laboratory of Chemistry in Ethnic Medicinal Resources Ministry of Education, Kunming, Yunnan, China
| | - Chunlin Yang
- Yunnan Minzu University, Key Laboratory of Chemistry in Ethnic Medicinal Resources Ministry of Education, Kunming, Yunnan, China
| | - Yijian Chen
- Yunnan Minzu University, Key Laboratory of Chemistry in Ethnic Medicinal Resources Ministry of Education, Kunming, Yunnan, China
| | - Jingxian Sun
- Yunnan Minzu University, Key Laboratory of Chemistry in Ethnic Medicinal Resources Ministry of Education, Kunming, Yunnan, China
| | - Haiying Yang
- Yunnan Minzu University, School of Chemistry and Environment, Kunming, Yunnan, China.
| | - Gang Du
- Yunnan Minzu University, Key Laboratory of Chemistry in Ethnic Medicinal Resources Ministry of Education, Kunming, Yunnan, China.
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Erkanli ME, El-Halabi K, Kim JR. Exploring the diversity of β-glucosidase: Classification, catalytic mechanism, molecular characteristics, kinetic models, and applications. Enzyme Microb Technol 2024; 173:110363. [PMID: 38041879 DOI: 10.1016/j.enzmictec.2023.110363] [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: 09/25/2023] [Revised: 11/17/2023] [Accepted: 11/18/2023] [Indexed: 12/04/2023]
Abstract
High-value chemicals and energy-related products can be produced from biomass. Biorefinery technology offers a sustainable and cost-effective method for this high-value conversion. β-glucosidase is one of the key enzymes in biorefinery processes, catalyzing the production of glucose from aryl-glycosides and cello-oligosaccharides via the hydrolysis of β-glycosidic bonds. Although β-glucosidase plays a critical catalytic role in the utilization of cellulosic biomass, its efficacy is often limited by substrate or product inhibitions, low thermostability, and/or insufficient catalytic activity. To provide a detailed overview of β-glucosidases and their benefits in certain desired applications, we collected and summarized extensive information from literature and public databases, covering β-glucosidases in different glycosidase hydrolase families and biological kingdoms. These β-glucosidases show differences in amino acid sequence, which are translated into varying degrees of the molecular properties critical in enzymatic applications. This review describes studies on the diversity of β-glucosidases related to the classification, catalytic mechanisms, key molecular characteristics, kinetics models, and applications, and highlights several β-glucosidases displaying high stability, activity, and resistance to glucose inhibition suitable for desired biotechnological applications.
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Affiliation(s)
- Mehmet Emre Erkanli
- Department of Chemical and Biomolecular Engineering, New York University, 6 MetroTech Center, Brooklyn, NY 11201, United States
| | - Khalid El-Halabi
- Department of Chemical and Biomolecular Engineering, New York University, 6 MetroTech Center, Brooklyn, NY 11201, United States
| | - Jin Ryoun Kim
- Department of Chemical and Biomolecular Engineering, New York University, 6 MetroTech Center, Brooklyn, NY 11201, United States.
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Dong CD, Patel AK, Madhavan A, Chen CW, Singhania RR. Significance of glycans in cellulolytic enzymes for lignocellulosic biorefinery - A review. BIORESOURCE TECHNOLOGY 2023; 379:128992. [PMID: 37011847 DOI: 10.1016/j.biortech.2023.128992] [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: 02/15/2023] [Revised: 03/28/2023] [Accepted: 03/29/2023] [Indexed: 05/03/2023]
Abstract
Lignocellulosic (LC) biomass is the most abundant renewable resource for mankind gravitating society towards sustainable solution for energy that can reduce the carbon footprint. The economic feasibility of 'biomass biorefinery' depends upon the efficiency cellulolytic enzymes which is the main crux. Its high production cost and low efficiencies are the major limitations, that need to be resolved. As the complexity of the genome increases, so does the complexity of the proteome, further facilitated by protein post-translational modifications (PTMs). Glycosylation is regarded the major PTMs and hardly any recent work is focused on importance of glycosylation in cellulase. By modifying protein side chains and glycans, superior cellulases with improved stability and efficiency can be obtained. Functional proteomics relies heavily on PTMs because they regulate activity, localization, and interactions with protein, lipid, nucleic acid, and cofactor molecules. O- and N- glycosylation in cellulases influences its characteristics adding positive attributes to the enzymes.
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Affiliation(s)
- Cheng-Di Dong
- Institute of Aquatic Science and Technology, National Kaohsiung University of Science and Technology, Kaohsiung City, Taiwan; Department of Marine Environmental Engineering, National Kaohsiung University of Science and Technology, Kaohsiung 81157, Taiwan; Sustainable Environment Research Center, National Kaohsiung University of Science and Technology, Kaohsiung City 81157, Taiwan
| | - Anil Kumar Patel
- Institute of Aquatic Science and Technology, National Kaohsiung University of Science and Technology, Kaohsiung City, Taiwan; Department of Marine Environmental Engineering, National Kaohsiung University of Science and Technology, Kaohsiung 81157, Taiwan; Centre for Energy and Environmental Sustainability, Lucknow 226 029, India
| | - Aravind Madhavan
- School of Biotechnology, Amrita Vishwa Vidyapeetham, Amritapuri, Kollam, Kerala 690 525, India
| | - Chiu-Wen Chen
- Institute of Aquatic Science and Technology, National Kaohsiung University of Science and Technology, Kaohsiung City, Taiwan; Department of Marine Environmental Engineering, National Kaohsiung University of Science and Technology, Kaohsiung 81157, Taiwan; Sustainable Environment Research Center, National Kaohsiung University of Science and Technology, Kaohsiung City 81157, Taiwan
| | - Reeta Rani Singhania
- Institute of Aquatic Science and Technology, National Kaohsiung University of Science and Technology, Kaohsiung City, Taiwan; Department of Marine Environmental Engineering, National Kaohsiung University of Science and Technology, Kaohsiung 81157, Taiwan; Centre for Energy and Environmental Sustainability, Lucknow 226 029, India.
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Ouyang B, Wang G, Zhang N, Zuo J, Huang Y, Zhao X. Recent Advances in β-Glucosidase Sequence and Structure Engineering: A Brief Review. Molecules 2023; 28:4990. [PMID: 37446652 DOI: 10.3390/molecules28134990] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2023] [Revised: 06/21/2023] [Accepted: 06/23/2023] [Indexed: 07/15/2023] Open
Abstract
β-glucosidases (BGLs) play a crucial role in the degradation of lignocellulosic biomass as well as in industrial applications such as pharmaceuticals, foods, and flavors. However, the application of BGLs has been largely hindered by issues such as low enzyme activity, product inhibition, low stability, etc. Many approaches have been developed to engineer BGLs to improve these enzymatic characteristics to facilitate industrial production. In this article, we review the recent advances in BGL engineering in the field, including the efforts from our laboratory. We summarize and discuss the BGL engineering studies according to the targeted functions as well as the specific strategies used for BGL engineering.
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Affiliation(s)
- Bei Ouyang
- College of Life Science, Jiangxi Normal University, Nanchang 330022, China
| | - Guoping Wang
- College of Life Science, Jiangxi Normal University, Nanchang 330022, China
| | - Nian Zhang
- College of Life Science, Jiangxi Normal University, Nanchang 330022, China
| | - Jiali Zuo
- School of Computer and Information Engineering, Jiangxi Normal University, Nanchang 330022, China
| | - Yunhong Huang
- College of Life Science, Jiangxi Normal University, Nanchang 330022, China
| | - Xihua Zhao
- College of Life Science, Jiangxi Normal University, Nanchang 330022, China
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Khamassi A, Dumon C. Enzyme synergy for plant cell wall polysaccharide degradation. Essays Biochem 2023; 67:521-531. [PMID: 37067158 DOI: 10.1042/ebc20220166] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 02/17/2023] [Accepted: 03/07/2023] [Indexed: 04/18/2023]
Abstract
Valorizing plant cell wall, marine and algal polysaccharides is of utmost importance for the development of the circular bioeconomy. This is because polysaccharides are by far the most abundant organic molecules found in nature with complex chemical structures that require a large set of enzymes for their degradation. Microorganisms produce polysaccharide-specific enzymes that act in synergy when performing hydrolysis. Although discovered since decades enzyme synergy is still poorly understood at the molecular level and thus it is difficult to harness and optimize. In the last few years, more attention has been given to improve and characterize enzyme synergy for polysaccharide valorization. In this review, we summarize literature to provide an overview of the different type of synergy involving carbohydrate modifying enzymes and the recent advances in the field exemplified by plant cell-wall degradation.
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Affiliation(s)
- Ahmed Khamassi
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France
- Institut de Pharmacologie et de Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, Toulouse, France
| | - Claire Dumon
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France
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Li S, Cao L, Yang X, Wu X, Xu S, Liu Y. Simultaneously optimizing multiple properties of β-glucosidase Bgl6 using combined (semi-)rational design strategies and investigation of the underlying mechanisms. BIORESOURCE TECHNOLOGY 2023; 374:128792. [PMID: 36842511 DOI: 10.1016/j.biortech.2023.128792] [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: 01/21/2023] [Revised: 02/20/2023] [Accepted: 02/21/2023] [Indexed: 06/18/2023]
Abstract
The performance of β-glucosidase during cellulose saccharification is determined by thermostability, activity and glucose tolerance. However, conflicts between them make it challenging to simultaneously optimize three properties. In this work, such a case was reported using Bgl6-M3 as a starting point. Firstly, four thermostability-enhancing mutations were obtained using computer-aided engineering strategies (mutant M7). Secondly, substrate binding pocket of M7 was reshaped, generating two mutations that increased activity but decreased glucose tolerance (mutant M9). Then a key region lining active site cavity was redesigned, resulting in three mutations that boosted glucose tolerance and activity. Finally, mutant M12 with simultaneously improved thermostability (half-life of 20-fold), activity (kcat/Km of 5.6-fold) and glucose tolerance (ΔIC50 of 200 mM) was obtained. Mechanisms for property improvement were elucidated by structural analysis and molecular dynamics simulations. Overall, the strategies used here and new insights into the underlying mechanisms may provide guidance for multi-property engineering of other enzymes.
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Affiliation(s)
- Shuifeng Li
- School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, PR China
| | - Lichuang Cao
- School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, PR China
| | - Xiangpeng Yang
- School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, PR China
| | - Xiangrui Wu
- School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, PR China
| | - Shujing Xu
- School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, PR China
| | - Yuhuan Liu
- School of Life Sciences, Sun Yat-Sen University, Guangzhou 510275, PR China.
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8
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Li M, Jiang B, Wu W, Wu S, Yang Y, Song J, Ahmad M, Jin Y. Current understanding and optimization strategies for efficient lignin-enzyme interaction: A review. Int J Biol Macromol 2022; 195:274-286. [PMID: 34883164 DOI: 10.1016/j.ijbiomac.2021.11.188] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 11/24/2021] [Accepted: 11/27/2021] [Indexed: 11/29/2022]
Abstract
From energy perspective, with abundant polysaccharides (45-85%), the renewable lignocellulosic is recognized as the 2nd generation feedstock for bioethanol and bio-based products production. Enzymatic hydrolysis is a critical pathway to yield fermentable monosaccharides from pretreated substrates of lignocellulose. Nevertheless, the lignin presence in lignocellulosic substrates leads to the low substrate enzymatic digestibility ascribed to the nonproductive adsorption. It has been reported that the water-soluble lignin (low molecular weight, sulfonated/sulfomethylated and graft polymer) enhance the rate of enzymatic digestibility, however, the catalytic mechanism of lignin-enzyme interaction remains elusive. In this review, optimization strategies for enzymatic hydrolysis based on the lignin structural modification, enzyme engineering, and different additives are critically reviewed. Lignin-enzyme interaction mechanism is also discussed (lignin and various cellulases). In addition, the mathematical models and simulation of lignin, cellulose and enzyme aims for promoting an integrated biomass-conversion process for sustainable production of value-added biofuels.
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Affiliation(s)
- Mohan Li
- Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, International Innovation Center for Forest Chemicals and Materials, China
| | - Bo Jiang
- Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, International Innovation Center for Forest Chemicals and Materials, China; Jiangsu Provincial Key Lab of Pulp and Paper Science and Technology, Nanjing Forestry University, Nanjing 210037, China
| | - Wenjuan Wu
- Jiangsu Provincial Key Lab of Pulp and Paper Science and Technology, Nanjing Forestry University, Nanjing 210037, China
| | - Shufang Wu
- Jiangsu Provincial Key Lab of Pulp and Paper Science and Technology, Nanjing Forestry University, Nanjing 210037, China
| | - Yiqin Yang
- Jiangsu Provincial Key Lab of Pulp and Paper Science and Technology, Nanjing Forestry University, Nanjing 210037, China
| | - Junlong Song
- Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, International Innovation Center for Forest Chemicals and Materials, China; Jiangsu Provincial Key Lab of Pulp and Paper Science and Technology, Nanjing Forestry University, Nanjing 210037, China
| | - Mehraj Ahmad
- Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, International Innovation Center for Forest Chemicals and Materials, China; Jiangsu Provincial Key Lab of Pulp and Paper Science and Technology, Nanjing Forestry University, Nanjing 210037, China
| | - Yongcan Jin
- Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, International Innovation Center for Forest Chemicals and Materials, China; Jiangsu Provincial Key Lab of Pulp and Paper Science and Technology, Nanjing Forestry University, Nanjing 210037, China.
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Sun N, Liu X, Wang X, Shi H, Zhang H, Li L, Na W, Guan Q. Optimization of fermentation conditions for the production of acidophilic β-glucosidase by Trichoderma reesei S12 from mangrove soil. BIOTECHNOL BIOTEC EQ 2022. [DOI: 10.1080/13102818.2021.1984989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022] Open
Affiliation(s)
- Nan Sun
- Lab of Animal Nutrition, Reproduction & Breeding, College of Animal Science and Technology, Hainan University, Haikou, Hainan, P.R.China
| | - Xiaoxuan Liu
- Lab of Animal Nutrition, Reproduction & Breeding, College of Animal Science and Technology, Hainan University, Haikou, Hainan, P.R.China
| | - Xuemei Wang
- Lab of Animal Nutrition, Reproduction & Breeding, College of Animal Science and Technology, Hainan University, Haikou, Hainan, P.R.China
| | - Huiyu Shi
- Lab of Animal Nutrition, Reproduction & Breeding, College of Animal Science and Technology, Hainan University, Haikou, Hainan, P.R.China
| | - Haiwen Zhang
- Lab of Animal Nutrition, Reproduction & Breeding, College of Animal Science and Technology, Hainan University, Haikou, Hainan, P.R.China
| | - Lianbin Li
- Lab of Animal Nutrition, Reproduction & Breeding, College of Animal Science and Technology, Hainan University, Haikou, Hainan, P.R.China
| | - Wei Na
- Lab of Animal Genetics, Reproduction & Breeding, College of Animal Science and Technology, Hainan University, Haikou, Hainan, P.R.China
| | - Qingfeng Guan
- Lab of Microorganism Resource and Utilization Research, School of Life Sciences, Hainan University, Haikou, Hainan, P.R.China
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Fungal cellulases: protein engineering and post-translational modifications. Appl Microbiol Biotechnol 2021; 106:1-24. [PMID: 34889986 DOI: 10.1007/s00253-021-11723-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2021] [Revised: 11/28/2021] [Accepted: 11/30/2021] [Indexed: 12/18/2022]
Abstract
Enzymatic degradation of lignocelluloses into fermentable sugars to produce biofuels and other biomaterials is critical for environmentally sustainable development and energy resource supply. However, there are problems in enzymatic cellulose hydrolysis, such as the complex cellulase composition, low degradation efficiency, high production cost, and post-translational modifications (PTMs), all of which are closely related to specific characteristics of cellulases that remain unclear. These problems hinder the practical application of cellulases. Due to the rapid development of computer technology in recent years, computer-aided protein engineering is being widely used, which also brings new opportunities for the development of cellulases. Especially in recent years, a large number of studies have reported on the application of computer-aided protein engineering in the development of cellulases; however, these articles have not been systematically reviewed. This article focused on the aspect of protein engineering and PTMs of fungal cellulases. In this manuscript, the latest literatures and the distribution of potential sites of cellulases for engineering have been systematically summarized, which provide reference for further improvement of cellulase properties. KEY POINTS: •Rational design based on virtual mutagenesis can improve cellulase properties. •Modifying protein side chains and glycans helps obtain superior cellulases. •N-terminal glutamine-pyroglutamate conversion stabilizes fungal cellulases.
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Thermostable cellulose saccharifying microbial enzymes: Characteristics, recent advances and biotechnological applications. Int J Biol Macromol 2021; 188:226-244. [PMID: 34371052 DOI: 10.1016/j.ijbiomac.2021.08.024] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Revised: 07/19/2021] [Accepted: 08/03/2021] [Indexed: 12/12/2022]
Abstract
Cellulases play a promising role in the bioconversion of renewable lignocellulosic biomass into fermentable sugars which are subsequently fermented to biofuels and other value-added chemicals. Besides biofuel industries, they are also in huge demand in textile, detergent, and paper and pulp industries. Low titres of cellulase production and processing are the main issues that contribute to high enzyme cost. The success of ethanol-based biorefinery depends on high production titres and the catalytic efficiency of cellulases functional at elevated temperatures with acid/alkali tolerance and the low cost. In view of their wider application in various industrial processes, stable cellulases that are active at elevated temperatures in the acidic-alkaline pH ranges, and organic solvents and salt tolerance would be useful. This review provides a recent update on the advances made in thermostable cellulases. Developments in their sources, characteristics and mechanisms are updated. Various methods such as rational design, directed evolution, synthetic & system biology and immobilization techniques adopted in evolving cellulases with ameliorated thermostability and characteristics are also discussed. The wide range of applications of thermostable cellulases in various industrial sectors is described.
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12
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Lim SJ, Oslan SN. Native to designed: microbial -amylases for industrial applications. PeerJ 2021; 9:e11315. [PMID: 34046253 PMCID: PMC8139272 DOI: 10.7717/peerj.11315] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Accepted: 03/30/2021] [Indexed: 12/31/2022] Open
Abstract
Background -amylases catalyze the endo-hydrolysis of -1,4-D-glycosidic bonds in starch into smaller moieties. While industrial processes are usually performed at harsh conditions, -amylases from mainly the bacteria, fungi and yeasts are preferred for their stabilities (thermal, pH and oxidative) and specificities (substrate and product). Microbial -amylases can be purified and characterized for industrial applications. While exploring novel enzymes with these properties in the nature is time-costly, the advancements in protein engineering techniques including rational design, directed evolution and others have privileged their modifications to exhibit industrially ideal traits. However, the commentary on the strategies and preferably mutated residues are lacking, hindering the design of new mutants especially for enhanced substrate specificity and oxidative stability. Thus, our review ensures wider accessibility of the previously reported experimental findings to facilitate the future engineering work. Survey methodology and objectives A traditional review approach was taken to focus on the engineering of microbial -amylases to enhance industrially favoured characteristics. The action mechanisms of - and -amylases were compared to avoid any bias in the research background. This review aimed to discuss the advances in modifying microbial -amylases via protein engineering to achieve longer half-life in high temperature, improved resistance (acidic, alkaline and oxidative) and enhanced specificities (substrate and product). Captivating results were discussed in depth, including the extended half-life at 100C, pH 3.5 and 10, 1.8 M hydrogen peroxide as well as enhanced substrate (65.3%) and product (42.4%) specificities. These shed light to the future microbial -amylase engineering in achieving paramount biochemical traits ameliorations to apt in the industries. Conclusions Microbial -amylases can be tailored for specific industrial applications through protein engineering (rational design and directed evolution). While the critical mutation points are dependent on respective enzymes, formation of disulfide bridge between cysteine residues after mutations is crucial for elevated thermostability. Amino acids conversion to basic residues was reported for enhanced acidic resistance while hydrophobic interaction resulted from mutated hydrophobic residues in carbohydrate-binding module or surface-binding sites is pivotal for improved substrate specificity. Substitution of oxidation-prone methionine residues with non-polar residues increases the enzyme oxidative stability. Hence, this review provides conceptual advances for the future microbial -amylases designs to exhibit industrially significant characteristics. However, more attention is needed to enhance substrate specificity and oxidative stability since they are least reported.
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Affiliation(s)
- Si Jie Lim
- Enzyme Technology Laboratory, VacBio 5, Institute of Bioscience, Universiti Putra Malaysia, Serdang, Selangor, Malaysia.,Enzyme and Microbial Technology (EMTech) Research Centre, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, Serdang, Selangor, Malaysia
| | - Siti Nurbaya Oslan
- Enzyme Technology Laboratory, VacBio 5, Institute of Bioscience, Universiti Putra Malaysia, Serdang, Selangor, Malaysia.,Enzyme and Microbial Technology (EMTech) Research Centre, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, Serdang, Selangor, Malaysia.,Department of Biochemistry, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, Serdang, Selangor, Malaysia
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13
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A novel β-glucosidase from a hot-spring metagenome shows elevated thermal stability and tolerance to glucose and ethanol. Enzyme Microb Technol 2021; 145:109764. [PMID: 33750538 DOI: 10.1016/j.enzmictec.2021.109764] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 01/21/2021] [Accepted: 01/28/2021] [Indexed: 12/22/2022]
Abstract
β-glucosidase causes hydrolysis of β-1,4-glycosidic bond in glycosides and oligosaccharides. It is an industrially important enzyme owing to its potential in biomass processing applications. In this study, computational screening of an extreme temperature aquatic habitat metagenomic resource was done, leading to the identification of a novel gene, bglM, encoding a β-glucosidase. The comparative protein sequence and homology structure analyses designated it as a GH1 family β-glucosidase. The bglM gene was expressed in a heterologous host, Escherichia coli. The purified protein, BglM, was biochemically characterized for β-glucosidase activity. BglM exhibited noteworthy hydrolytic potential towards cellobiose and lactose. BglM, showed substantial catalytic activity in the pH range of 5.0-7.0 and at the temperature 40 °C-70 °C. The enzyme was found quite stable at 50 °C with a loss of hardly 20% after 40 h of heat exposure. Furthermore, any drastically negative effect was not observed on the enzyme's activity in the presence of metal ions, non-ionic surfactants, metal chelating, and denaturing agents. A significantly high glucose tolerance, retaining 80% relative activity at 1 M, and 40% at 5 M glucose, and ethanol tolerance, exhibiting 80% relative activity in 10% ethanol, enrolled BglM as a promising enzyme for cellulose saccharification. Furthermore, its ability to catalyze the hydrolysis of daidzin and polydatin ascertained it as an admirably suited biocatalyst for enhancement of nutritional values in soya and wine industries.
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