1
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Nong D, Haviland ZK, Zexer N, Pfaff SA, Cosgrove DJ, Tien M, Anderson CT, Hancock WO. Single-molecule tracking reveals dual front door/back door inhibition of Cel7A cellulase by its product cellobiose. Proc Natl Acad Sci U S A 2024; 121:e2322567121. [PMID: 38648472 PMCID: PMC11067010 DOI: 10.1073/pnas.2322567121] [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: 01/04/2024] [Accepted: 03/18/2024] [Indexed: 04/25/2024] Open
Abstract
Degrading cellulose is a key step in the processing of lignocellulosic biomass into bioethanol. Cellobiose, the disaccharide product of cellulose degradation, has been shown to inhibit cellulase activity, but the mechanisms underlying product inhibition are not clear. We combined single-molecule imaging and biochemical investigations with the goal of revealing the mechanism by which cellobiose inhibits the activity of Trichoderma reesei Cel7A, a well-characterized exo-cellulase. We find that cellobiose slows the processive velocity of Cel7A and shortens the distance moved per encounter; effects that can be explained by cellobiose binding to the product release site of the enzyme. Cellobiose also strongly inhibits the binding of Cel7A to immobilized cellulose, with a Ki of 2.1 mM. The isolated catalytic domain (CD) of Cel7A was also inhibited to a similar degree by cellobiose, and binding of an isolated carbohydrate-binding module to cellulose was not inhibited by cellobiose, suggesting that cellobiose acts on the CD alone. Finally, cellopentaose inhibited Cel7A binding at micromolar concentrations without affecting the enzyme's velocity of movement along cellulose. Together, these results suggest that cellobiose inhibits Cel7A activity both by binding to the "back door" product release site to slow activity and to the "front door" substrate-binding tunnel to inhibit interaction with cellulose. These findings point to strategies for engineering cellulases to reduce product inhibition and enhance cellulose degradation, supporting the growth of a sustainable bioeconomy.
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Affiliation(s)
- Daguan Nong
- Department of Biomedical Engineering, Pennsylvania State University, University Park, PA16802
| | - Zachary K. Haviland
- Department of Biomedical Engineering, Pennsylvania State University, University Park, PA16802
| | - Nerya Zexer
- Department of Biology, Pennsylvania State University, University Park, PA16802
| | - Sarah A. Pfaff
- Department of Biology, Pennsylvania State University, University Park, PA16802
- Intercollege Graduate Degree Program in Plant Biology, Department of Biology, The Pennsylvania State University, University Park, PA16802
| | - Daniel J. Cosgrove
- Department of Biology, Pennsylvania State University, University Park, PA16802
| | - Ming Tien
- Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, PA16802
| | - Charles T. Anderson
- Department of Biology, Pennsylvania State University, University Park, PA16802
| | - William O. Hancock
- Department of Biomedical Engineering, Pennsylvania State University, University Park, PA16802
- Department of Chemistry, Pennsylvania State University, University Park, PA16802
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2
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Dodda SR, Hossain M, Mondal S, Das S, Khator (Jain) S, Aikat K, Mukhopadhyay SS. The S-S bridge mutation between the A2 and A4 loops (T416C-I432C) of Cel7A of Aspergillus fumigatus enhances catalytic activity and thermostability. Appl Environ Microbiol 2024; 90:e0232923. [PMID: 38440989 PMCID: PMC11022540 DOI: 10.1128/aem.02329-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Accepted: 01/28/2024] [Indexed: 03/06/2024] Open
Abstract
Disulfide bonds are important for maintaining the structural conformation and stability of the protein. The introduction of the disulfide bond is a promising strategy to increase the thermostability of the protein. In this report, cysteine residues are introduced to form disulfide bonds in the Glycoside Hydrolase family GH 7 cellobiohydrolase (GH7 CBHs) or Cel7A of Aspergillus fumigatus. Disulfide by Design 2.0 (DbD2), an online tool is used for the detection of the mutation sites. Mutations are created (D276C-G279C; DSB1, D322C-G327C; DSB2, T416C-I432C; DSB3, G460C-S465C; DSB4) inside and outside of the peripheral loops but, not in the catalytic region. The introduction of cysteine in the A2 and A4 loop of DSB3 mutant showed higher thermostability (70% activity at 70°C), higher substrate affinity (Km = 0.081 mM) and higher catalytic activity (Kcat = 9.75 min-1; Kcat/Km = 120.37 mM min-1) compared to wild-type AfCel7A (50% activity at 70°C; Km = 0.128 mM; Kcat = 4.833 min-1; Kcat/Km = 37.75 mM min-1). The other three mutants with high B factor showed loss of thermostability and catalytic activity. Molecular dynamic simulations revealed that the mutation T416C-I432C makes the tunnel wider (DSB3: 13.6 Å; Wt: 5.3 Å) at the product exit site, giving flexibility in the entrance region or mobility of the substrate in the exit region. It may facilitate substrate entry into the catalytic tunnel and release the product faster than the wild type, whereas in other mutants, the tunnel is not prominent (DSB4), the exit is lost (DSB1), and the ligand binding site is absent (DSB2). This is the first report of the gain of function of both thermostability and enzyme activity of cellobiohydrolase Cel7A by disulfide bond engineering in the loop.IMPORTANCEBioethanol is one of the cleanest renewable energy and alternatives to fossil fuels. Cost efficient bioethanol production can be achieved through simultaneous saccharification and co-fermentation that needs active polysaccharide degrading enzymes. Cellulase enzyme complex is a crucial enzyme for second-generation bioethanol production from lignocellulosic biomass. Cellobiohydrolase (Cel7A) is an important member of this complex. In this work, we engineered (disulfide bond engineering) the Cel7A to increase its thermostability and catalytic activity which is required for its industrial application.
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Affiliation(s)
- Subba Reddy Dodda
- Department of Biotechnology, National Institute of Technology Durgapur, Durgapur, West Bengal, India
| | - Musaddique Hossain
- Department of Biotechnology, National Institute of Technology Durgapur, Durgapur, West Bengal, India
| | - Sudipa Mondal
- Department of Biotechnology, National Institute of Technology Durgapur, Durgapur, West Bengal, India
| | - Shalini Das
- Department of Biotechnology, National Institute of Technology Durgapur, Durgapur, West Bengal, India
| | - Sneha Khator (Jain)
- Department of Biotechnology, National Institute of Technology Durgapur, Durgapur, West Bengal, India
| | - Kaustav Aikat
- Department of Biotechnology, National Institute of Technology Durgapur, Durgapur, West Bengal, India
| | - Sudit S. Mukhopadhyay
- Department of Biotechnology, National Institute of Technology Durgapur, Durgapur, West Bengal, India
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3
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Wang M, Wang H, Gao C, Wei W, Liu J, Chen X, Hu G, Song W, Wu J, Zhang F, Liu L. Efficient production of protocatechuic acid using systems engineering of Escherichia coli. Metab Eng 2024; 82:134-146. [PMID: 38369051 DOI: 10.1016/j.ymben.2024.02.003] [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: 11/04/2023] [Revised: 01/21/2024] [Accepted: 02/10/2024] [Indexed: 02/20/2024]
Abstract
Protocatechuic acid (3, 4-dihydroxybenzoic acid, PCA) is widely used in the pharmaceuticals, health food, and cosmetics industries owing to its diverse biological activities. However, the inhibition of 3-dehydroshikimate dehydratase (AroZ) by PCA and its toxicity to cells limit the efficient production of PCA in Escherichia coli. In this study, a high-level strain of 3-dehydroshikimate, E. coli DHS01, was developed by blocking the carbon flow from the shikimate-overproducing strain E. coli SA09. Additionally, the PCA biosynthetic pathway was established in DHS01 by introducing the high-activity ApAroZ. Subsequently, the protein structure and catalytic mechanism of 3-dehydroshikimate dehydratase from Acinetobacter pittii PHEA-2 (ApAroZ) were clarified. The variant ApAroZR363A, achieved by modulating the conformational dynamics of ApAroZ, effectively relieved product inhibition. Additionally, the tolerance of the strain E. coli PCA04 to PCA was enhanced by adaptive laboratory evolution, and a biosensor-assisted high-throughput screening method was designed and implemented to expedite the identification of high-performance PCA-producing strains. Finally, in a 5 L bioreactor, the final strain PCA05 achieved the highest PCA titer of 46.65 g/L, a yield of 0.23 g/g, and a productivity of 1.46 g/L/h for PCA synthesis from glucose using normal fed-batch fermentation. The strategies described herein serve as valuable guidelines for the production of other high-value and toxic products.
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Affiliation(s)
- Ming Wang
- School of Biotechnology and Key Laboratory of Industrial Biotechnology of Ministry of Education, Jiangnan University, Wuxi, 214122, China
| | - Haomiao Wang
- School of Biotechnology and Key Laboratory of Industrial Biotechnology of Ministry of Education, Jiangnan University, Wuxi, 214122, China
| | - Cong Gao
- School of Biotechnology and Key Laboratory of Industrial Biotechnology of Ministry of Education, Jiangnan University, Wuxi, 214122, China
| | - Wanqing Wei
- School of Biotechnology and Key Laboratory of Industrial Biotechnology of Ministry of Education, Jiangnan University, Wuxi, 214122, China
| | - Jia Liu
- School of Biotechnology and Key Laboratory of Industrial Biotechnology of Ministry of Education, Jiangnan University, Wuxi, 214122, China
| | - Xiulai Chen
- School of Biotechnology and Key Laboratory of Industrial Biotechnology of Ministry of Education, Jiangnan University, Wuxi, 214122, China
| | - Guipeng Hu
- School of Life Sciences and Health Engineering, Jiangnan University, Wuxi, 214122, China
| | - Wei Song
- School of Life Sciences and Health Engineering, Jiangnan University, Wuxi, 214122, China
| | - Jing Wu
- School of Life Sciences and Health Engineering, Jiangnan University, Wuxi, 214122, China
| | - Fan Zhang
- School of Life Sciences and Technology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Liming Liu
- School of Biotechnology and Key Laboratory of Industrial Biotechnology of Ministry of Education, Jiangnan University, Wuxi, 214122, China.
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4
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Pavale S, Dalei SK, Sokhal P, Biswas B, Meena K, Adlakha N. Engineering phenylalanine ammonia lyase to limit feedback inhibition by cinnamate and enhance biotransformation. Biotechnol J 2024; 19:e2300275. [PMID: 37861236 DOI: 10.1002/biot.202300275] [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: 06/08/2023] [Revised: 10/17/2023] [Accepted: 10/18/2023] [Indexed: 10/21/2023]
Abstract
Phenylalanine ammonia-lyase (PAL) is a crucial enzyme for various biotechnology applications, such as producing phenols, antioxidants, and nutraceuticals. However, feedback inhibition from its product, cinnamic acid, limits its forward reaction rate. Therefore, this study aims to address the feedback inhibition in PAL using enzyme engineering strategies. Random and site-directed mutagenesis approaches were utilized to screen mutant enzymes with ameliorated tolerance against cinnamic acid. A thermotolerant and cinnamate-tolerant mutant was rationally identified using a high throughput screening method and subsequent biochemical characterization. We evaluated cinnamate affinity among the seven rationally selected mutations, and the T102E mutation was identified as the most promising mutant. This mutant showed a six-fold reduction in the affinity of PAL for cinnamic acid and a two-fold increase in operational stability compared with native PAL. Furthermore, the enzyme was immobilized on carbon nanotubes to increase its robustness and reusability. The immobilized mutant PAL showed greater efficiency in the deamination of phenylalanine present in protein hydrolysate than its free form. The rationale behind the enhancement of cinnamate tolerance was validated using molecular dynamic simulations. Overall, the knowledge of the sequence-function relationship of PAL was applied to drive enzyme engineering to develop highly tolerant PAL.
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Affiliation(s)
- Siddhi Pavale
- Synthetic Biology and Bioprocessing group, Regional Centre for Biotechnology, NCR-Biotech Cluster, Faridabad, India
| | - Sudipt Kumar Dalei
- Synthetic Biology and Bioprocessing group, Regional Centre for Biotechnology, NCR-Biotech Cluster, Faridabad, India
| | - Preeti Sokhal
- Synthetic Biology and Bioprocessing group, Regional Centre for Biotechnology, NCR-Biotech Cluster, Faridabad, India
| | - Biswambhar Biswas
- Synthetic Biology and Bioprocessing group, Regional Centre for Biotechnology, NCR-Biotech Cluster, Faridabad, India
| | - Kunal Meena
- Synthetic Biology and Bioprocessing group, Regional Centre for Biotechnology, NCR-Biotech Cluster, Faridabad, India
| | - Nidhi Adlakha
- Synthetic Biology and Bioprocessing group, Regional Centre for Biotechnology, NCR-Biotech Cluster, Faridabad, India
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5
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Lu X, Li X, Zhao J. Improving enzymatic efficiency of β-glucosidases in cellulase system by altering its binding behavior to the insoluble substrate during bioconversion of lignocellulose. BIORESOURCE TECHNOLOGY 2024; 391:129974. [PMID: 37939741 DOI: 10.1016/j.biortech.2023.129974] [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: 09/12/2023] [Revised: 10/31/2023] [Accepted: 11/01/2023] [Indexed: 11/10/2023]
Abstract
The enzymatic efficiency of β-glucosidases is influenced by their binding behavior onto insoluble substrates (cellulose and lignin) during bioconversion of lignocellulose. This study suggested that the Bgl3 protein (Aspergillus fumigatus) showed strong adsorption affinity to lignin and the Bgl1 protein (Penicillium oxalicum) tended to adsorb to cellulose. It indicated that the various surface properties of the fibronectin type Ш-like domain (FnIII) led to different binding properties of β-glucosidases by investigating their binding mechanism. By engineering β-glucosidases' FnIII domain, Bgl3-1 and Bgl1-3 were constructed, which both showed lower binding capacities to insoluble substrates. As well as for Bgl1-3, its sensitivity to the phenolic component was also eased. Based on that, the reconstructed protein showed high catalytic efficiency during the enzymatic hydrolysis of corn stover by effectively transforming cellobiose to glucose. Thus, this study provided a new strategy to engineer β-glucosidases to enhance their performance in the cellulase system.
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Affiliation(s)
- Xianqin Lu
- State Key Laboratory of Microbial Technology, Shandong University, No.72, Binhai Road, Qingdao 266237, China
| | - Xuezhi Li
- State Key Laboratory of Microbial Technology, Shandong University, No.72, Binhai Road, Qingdao 266237, China
| | - Jian Zhao
- State Key Laboratory of Microbial Technology, Shandong University, No.72, Binhai Road, Qingdao 266237, China.
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6
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Liu P, Chen Y, Ma C, Ouyang J, Zheng Z. β-Galactosidase: a traditional enzyme given multiple roles through protein engineering. Crit Rev Food Sci Nutr 2023:1-20. [PMID: 38108277 DOI: 10.1080/10408398.2023.2292282] [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: 12/19/2023]
Abstract
β-Galactosidases are crucial carbohydrate-active enzymes that naturally catalyze the hydrolysis of galactoside bonds in oligo- and disaccharides. These enzymes are commonly used to degrade lactose and produce low-lactose and lactose-free dairy products that are beneficial for lactose-intolerant people. β-galactosidases exhibit transgalactosylation activity, and they have been employed in the synthesis of galactose-containing compounds such as galactooligosaccharides. However, most β-galactosidases have intrinsic limitations, such as low transglycosylation efficiency, significant product inhibition effects, weak thermal stability, and a narrow substrate spectrum, which greatly hinder their applications. Enzyme engineering offers a solution for optimizing their catalytic performance. The study of the enzyme's structure paves the way toward explaining catalytic mechanisms and increasing the efficiency of enzyme engineering. In this review, the structure features of β-galactosidases from different glycosyl hydrolase families and the catalytic mechanisms are summarized in detail to offer guidance for protein engineering. The properties and applications of β-galactosidases are discussed. Additionally, the latest progress in β-galactosidase engineering and the strategies employed are highlighted. Based on the combined analysis of structure information and catalytic mechanisms, the ultimate goal of this review is to furnish a thorough direction for β-galactosidases engineering and promote their application in the food and dairy industries.
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Affiliation(s)
- Peng Liu
- School of Grain Science and Technology, Jiangsu University of Science and Technology, Zhenjiang, People's Republic of China
- Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, College of Chemical Engineering, Nanjing Forestry University, Nanjing, People's Republic of China
| | - Yuehua Chen
- Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, College of Chemical Engineering, Nanjing Forestry University, Nanjing, People's Republic of China
| | - Cuiqing Ma
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, People's Republic of China
| | - Jia Ouyang
- Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, College of Chemical Engineering, Nanjing Forestry University, Nanjing, People's Republic of China
| | - Zhaojuan Zheng
- Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, College of Chemical Engineering, Nanjing Forestry University, Nanjing, People's Republic of China
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7
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Chaudhari YB, Várnai A, Sørlie M, Horn SJ, Eijsink VGH. Engineering cellulases for conversion of lignocellulosic biomass. Protein Eng Des Sel 2023; 36:gzad002. [PMID: 36892404 PMCID: PMC10394125 DOI: 10.1093/protein/gzad002] [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: 10/28/2022] [Revised: 02/13/2023] [Accepted: 02/24/2023] [Indexed: 03/10/2023] Open
Abstract
Lignocellulosic biomass is a renewable source of energy, chemicals and materials. Many applications of this resource require the depolymerization of one or more of its polymeric constituents. Efficient enzymatic depolymerization of cellulose to glucose by cellulases and accessory enzymes such as lytic polysaccharide monooxygenases is a prerequisite for economically viable exploitation of this biomass. Microbes produce a remarkably diverse range of cellulases, which consist of glycoside hydrolase (GH) catalytic domains and, although not in all cases, substrate-binding carbohydrate-binding modules (CBMs). As enzymes are a considerable cost factor, there is great interest in finding or engineering improved and robust cellulases, with higher activity and stability, easy expression, and minimal product inhibition. This review addresses relevant engineering targets for cellulases, discusses a few notable cellulase engineering studies of the past decades and provides an overview of recent work in the field.
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Affiliation(s)
- Yogesh B Chaudhari
- Faculty of Chemistry, Biotechnology, and Food Science, NMBU-Norwegian University of Life Sciences, P.O. Box 5003, 1432 Ås, Norway
| | - Anikó Várnai
- Faculty of Chemistry, Biotechnology, and Food Science, NMBU-Norwegian University of Life Sciences, P.O. Box 5003, 1432 Ås, Norway
| | - Morten Sørlie
- Faculty of Chemistry, Biotechnology, and Food Science, NMBU-Norwegian University of Life Sciences, P.O. Box 5003, 1432 Ås, Norway
| | - Svein J Horn
- Faculty of Chemistry, Biotechnology, and Food Science, NMBU-Norwegian University of Life Sciences, P.O. Box 5003, 1432 Ås, Norway
| | - Vincent G H Eijsink
- Faculty of Chemistry, Biotechnology, and Food Science, NMBU-Norwegian University of Life Sciences, P.O. Box 5003, 1432 Ås, Norway
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8
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Shi X, Wu D, Xu Y, Yu X. Engineering the optimum pH of β-galactosidase from Aspergillus oryzae for efficient hydrolysis of lactose. J Dairy Sci 2022; 105:4772-4782. [PMID: 35450720 DOI: 10.3168/jds.2021-21760] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2021] [Accepted: 02/19/2022] [Indexed: 11/19/2022]
Abstract
β-Galactosidase (lacA) from Aspergillus oryzae is widely used in the dairy industry. Its acidic pH optimum and severe product inhibition limit its application for lactose hydrolysis in milk. In the present study, structure-based sequence alignment was conducted to determine the candidate mutations to shift the pH optimum of lacA to the neutral range. The Y138F and Y364F mutants shifted the pH optimum of lacA from 4.5 to 5.5 and 6.0, respectively. The acid dissociation constant (pKa) values of catalytic acid/base residues with upwards shift were consistent with the increased pH optimum. All variants in the present study also alleviated galactose inhibition to various extents. Molecular dynamics demonstrated that the less rigid tertiary structures and lower galactose-binding free energy of Y138F and Y364F might facilitate the release of the end product. Both Y138F and Y364F mutants exhibited better hydrolytic ability than lacA in milk lactose hydrolysis. The higher pH optimum and lower galactose inhibition of Y138F and Y364F may explain their superiority over lacA. The Y138F and Y364F mutants in the present study showed potential in producing low-lactose milk, and our studies provide a novel strategy for engineering the pH optimum of glycoside hydrolase.
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Affiliation(s)
- Xin Shi
- Laboratory of Brewing Microbiology and Applied Enzymology, School of Biotechnology, Jiangnan University, Wuxi 214122, People's Republic of China; Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, People's Republic of China
| | - Dan Wu
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, People's Republic of China
| | - Yan Xu
- Laboratory of Brewing Microbiology and Applied Enzymology, School of Biotechnology, Jiangnan University, Wuxi 214122, People's Republic of China; Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, People's Republic of China
| | - Xiaowei Yu
- Laboratory of Brewing Microbiology and Applied Enzymology, School of Biotechnology, Jiangnan University, Wuxi 214122, People's Republic of China; Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, People's Republic of China.
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9
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Production of phenylpyruvic acid by engineered l-amino acid deaminase from Proteus mirabilis. Biotechnol Lett 2022; 44:635-642. [DOI: 10.1007/s10529-022-03245-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Accepted: 03/07/2022] [Indexed: 12/20/2022]
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10
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Liu P, Wu J, Liu J, Ouyang J. Engineering of a β-galactosidase from Bacillus coagulans to relieve product inhibition and improve hydrolysis performance. J Dairy Sci 2021; 104:10566-10575. [PMID: 34334201 DOI: 10.3168/jds.2021-20388] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Accepted: 05/27/2021] [Indexed: 11/19/2022]
Abstract
Most β-galactosidases reported are sensitive to the end product (galactose), making it the rate-limiting component for the efficient degradation of lactose through the enzymatic route. Therefore, there is ongoing interest in searching for galactose-tolerant β-galactosidases. In the present study, the predicted galactose-binding residues of β-galactosidase from Bacillus coagulans, which were determined by molecular docking, were selected for alanine substitution. The asparagine residue at position 148 (N148) is correlated with the reduction of galactose inhibition. Saturation mutations revealed that the N148C, N148D, N148S, and N148G mutants exhibited weaker galactose inhibition effects. The N148D mutant was used for lactose hydrolysis and exhibited a higher hydrolytic rate. Molecular dynamics revealed that the root mean square deviation and gyration radius of the N148D-galactose complex were higher than those of wild-type enzyme-galactose complex. In addition, the N148D mutant had a higher absolute binding free-energy value. All these factors may lead to a lower affinity between galactose and the mutant enzyme. The use of mutant enzyme may have potential value in lactose hydrolysis.
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Affiliation(s)
- Peng Liu
- Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Nanjing Forestry University, Nanjing 210037, People's Republic of China; College of Forestry, Nanjing Forestry University, Nanjing 210037, People's Republic of China
| | - Jiawei Wu
- Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Nanjing Forestry University, Nanjing 210037, People's Republic of China; College of Chemical Engineering, Nanjing Forestry University, Nanjing 210037, People's Republic of China
| | - Junhua Liu
- Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Nanjing Forestry University, Nanjing 210037, People's Republic of China; College of Chemical Engineering, Nanjing Forestry University, Nanjing 210037, People's Republic of China
| | - Jia Ouyang
- Jiangsu Co-Innovation Center of Efficient Processing and Utilization of Forest Resources, Nanjing Forestry University, Nanjing 210037, People's Republic of China; College of Chemical Engineering, Nanjing Forestry University, Nanjing 210037, People's Republic of China.
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11
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Sinitsyn AP, Sinitsyna OA. Bioconversion of Renewable Plant Biomass. Second-Generation Biofuels: Raw Materials, Biomass Pretreatment, Enzymes, Processes, and Cost Analysis. BIOCHEMISTRY (MOSCOW) 2021; 86:S166-S195. [PMID: 33827407 DOI: 10.1134/s0006297921140121] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The review discusses various aspects of renewable plant biomass conversion and production of the second-generation biofuels, including the types of plant biomass, its composition and reaction ability in the enzymatic hydrolysis, and various pretreatment methods for increasing the biomass reactivity. Conversion of plant biomass into sugars requires the use of a complex of enzymes, the composition of which should be adapted to the biomass type and the pretreatment method. The efficiency of enzymatic hydrolysis can be increased by optimizing the composition of the enzymatic complex and by increasing the catalytic activity and operational stability of its constituent enzymes. The availability of active enzyme producers also plays an important role. Examples of practical implementation and scaling of processes for the production of second-generation biofuels are presented together with the cost analysis of bioethanol production.
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Affiliation(s)
- Arkadij P Sinitsyn
- Bakh Institute of Biochemistry, Federal Research Centre "Fundamentals of Biotechnology", Russian Academy of Sciences, Moscow, 119071, Russia. .,Faculty of Chemistry, Lomonosov Moscow State University, Moscow, 119991, Russia
| | - Olga A Sinitsyna
- Faculty of Chemistry, Lomonosov Moscow State University, Moscow, 119991, Russia
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12
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Summers SR, Alamdari S, Kraft CJ, Brunecky R, Pfaendtner J, Kaar JL. Substitution of distal and active site residues reduces product inhibition of E1 from Acidothermus Cellulolyticus. Protein Eng Des Sel 2021; 34:6476618. [PMID: 34935952 DOI: 10.1093/protein/gzab031] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Revised: 09/22/2021] [Accepted: 11/13/2021] [Indexed: 11/14/2022] Open
Abstract
Cellulases are largely afflicted by inhibition from their reaction products, especially at high-substrate loading, which represents a major challenge for biomass processing. This challenge was overcome for endoglucanase 1 (E1) from Acidothermus cellulolyticus by identifying a large conformational change involving distal residues upon binding cellobiose. Having introduced alanine substitutions at each of these residues, we identified several mutations that reduced cellobiose inhibition of E1, including W212A, W213A, Q247A, W249A and F250A. One of the mutations (W212A) resulted in a 47-fold decrease in binding affinity of cellobiose as well as a 5-fold increase in the kcat. The mutation further increased E1 activity on Avicel and dilute-acid treated corn stover and enhanced its productivity at high-substrate loadings. These findings were corroborated by funnel metadynamics, which showed that the W212A substitution led to reduced affinity for cellobiose in the +1 and +2 binding sites due to rearrangement of key cellobiose-binding residues.
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Affiliation(s)
- Samantha R Summers
- Department of Chemical and Biological Engineering, University of Colorado, 3415 Colorado Avenue, Boulder, CO 80309, USA
| | - Sarah Alamdari
- Department of Chemical Engineering, University of Washington, 3781 Okanogan Lane NE, Seattle, WA 98195-1750, USA
| | - Casey J Kraft
- Department of Chemical and Biological Engineering, University of Colorado, 3415 Colorado Avenue, Boulder, CO 80309, USA
| | - Roman Brunecky
- Biosciences Center, National Renewable Energy Lab, 15013 Denver W Pkwy, Golden, CO 80401, USA
| | - Jim Pfaendtner
- Department of Chemical Engineering, University of Washington, 3781 Okanogan Lane NE, Seattle, WA 98195-1750, USA
| | - Joel L Kaar
- Department of Chemical and Biological Engineering, University of Colorado, 3415 Colorado Avenue, Boulder, CO 80309, USA
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13
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Maltose binding site 2 mutations affect product inhibition of Bacillus circulans STB01 cyclodextrin glycosyltransferase. Int J Biol Macromol 2021; 175:254-261. [PMID: 33561459 DOI: 10.1016/j.ijbiomac.2021.02.033] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 02/04/2021] [Accepted: 02/04/2021] [Indexed: 11/23/2022]
Abstract
The efficiency of enzymatic cyclodextrin production using cyclodextrin glycosyltransferases (CGTases) is limited by product inhibition. In this study, maltose binding site 2 (MBS2) of the β-CGTase from Bacillus circulans STB01 was modified to decrease product inhibition. First, two point mutants were prepared at position 599 (A599V and A599N). Then, two double mutants incorporating alanine at position 633 (A599N/Y633A and A599V/Y633A) were prepared. Finally, the entire MBS2 region was replaced by that of the α-CGTase from Paenibacillus macerans JFB05-01 to form multipoint mutant MBS2 β → α. All five mutants exhibited mixed-type product inhibition, although both the competitive and uncompetitive components of this inhibition were decreased. The total cyclization activities of A599N, A599V and A599V/Y633A were 15.6%, 76.8% and 70.9% lower than that of the wild-type, respectively, while that of A599N/Y633A was 22.4% higher. Among the mutants, only MBS2 β → α showed catalytic efficiency (kcat/Km) comparable with that of the wild-type. Moreover, A599N, A599N/Y633A and MBS2 β → α produced cyclodextrin yields 13.1%, 15.8% and 19.7% greater than that of the wild-type, respectively. These results suggest that A599N, A599N/Y633A and MBS2 β → α may be more suitable than the wild-type for cyclodextrin production.
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14
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Zou G, Bao D, Wang Y, Zhou S, Xiao M, Yang Z, Wang Y, Zhou Z. Alleviating product inhibition of Trichoderma reesei cellulase complex with a product-activated mushroom endoglucanase. BIORESOURCE TECHNOLOGY 2021; 319:124119. [PMID: 32957048 DOI: 10.1016/j.biortech.2020.124119] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Revised: 09/08/2020] [Accepted: 09/09/2020] [Indexed: 06/11/2023]
Abstract
Product inhibition of cellulase is a challenging issue in industrial processes. Here, we introduced a product-activated mushroom cellulase, PaCel3A from Polyporus arcularius, into Trichoderma reesei. The filter paper activity, carboxymethyl cellulase activity, and saccharification efficiency (substrate: pretreated rice straw, PRS) of transformants increased significantly with this enzyme (by 18.4-26.8%, 13.8-22.8%, and 17.0%, respectively). A mutant of PaCel3A, PaCel3AM, obtained based on B-factor analysis, saturated mutagenesis, and residual activity assay, showed improved thermostability. The PRS saccharification efficiency using the cellulase complex from T. reesei transformants overexpressing pacel3am increased by 56.4%-63.0%. In addition, the T. reesei cellulase complex obtained by adding the purified recombinant PaCel3AM from T. reesei (rCel3aM-tr) to hydrolyze PRS resulted in increased reducing sugar yields at all sampling points, outperforming the cellulase complexes without rCel3aM-tr. These results suggest that introducing product-activated cellulase genes is a simple and feasible method to alleviate the product inhibition of cellulase.
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Affiliation(s)
- Gen Zou
- Shanghai Key Laboratory of Agricultural Genetics and Breeding; Institute of Edible Fungi, Shanghai Academy of Agriculture Science, 1000 Jinqi Rd, Fengxian 201403, Shanghai, China; CAS-Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Science, Fenglin Rd 300, Shanghai 200032, China.
| | - Dapeng Bao
- Shanghai Key Laboratory of Agricultural Genetics and Breeding; Institute of Edible Fungi, Shanghai Academy of Agriculture Science, 1000 Jinqi Rd, Fengxian 201403, Shanghai, China.
| | - Ying Wang
- Shanghai Key Laboratory of Agricultural Genetics and Breeding; Institute of Edible Fungi, Shanghai Academy of Agriculture Science, 1000 Jinqi Rd, Fengxian 201403, Shanghai, China
| | - Sichi Zhou
- Shanghai Key Laboratory of Agricultural Genetics and Breeding; Institute of Edible Fungi, Shanghai Academy of Agriculture Science, 1000 Jinqi Rd, Fengxian 201403, Shanghai, China
| | - Meili Xiao
- CAS-Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Science, Fenglin Rd 300, Shanghai 200032, China.
| | - Zhanshan Yang
- Shanghai Key Laboratory of Agricultural Genetics and Breeding; Institute of Edible Fungi, Shanghai Academy of Agriculture Science, 1000 Jinqi Rd, Fengxian 201403, Shanghai, China
| | - Yinmei Wang
- CAS-Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Science, Fenglin Rd 300, Shanghai 200032, China.
| | - Zhihua Zhou
- CAS-Key Laboratory of Synthetic Biology, CAS Center for Excellence in Molecular Plant Sciences, Institute of Plant Physiology and Ecology, Chinese Academy of Science, Fenglin Rd 300, Shanghai 200032, China.
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15
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Bernardi AV, Gerolamo LE, de Gouvêa PF, Yonamine DK, Pereira LMS, de Oliveira AHC, Uyemura SA, Dinamarco TM. LPMO AfAA9_B and Cellobiohydrolase AfCel6A from A. fumigatus Boost Enzymatic Saccharification Activity of Cellulase Cocktail. Int J Mol Sci 2020; 22:E276. [PMID: 33383972 PMCID: PMC7795096 DOI: 10.3390/ijms22010276] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Revised: 12/21/2020] [Accepted: 12/24/2020] [Indexed: 01/02/2023] Open
Abstract
Cellulose is the most abundant polysaccharide in lignocellulosic biomass, where it is interlinked with lignin and hemicellulose. Bioethanol can be produced from biomass. Since breaking down biomass is difficult, cellulose-active enzymes secreted by filamentous fungi play an important role in degrading recalcitrant lignocellulosic biomass. We characterized a cellobiohydrolase (AfCel6A) and lytic polysaccharide monooxygenase LPMO (AfAA9_B) from Aspergillus fumigatus after they were expressed in Pichia pastoris and purified. The biochemical parameters suggested that the enzymes were stable; the optimal temperature was ~60 °C. Further characterization revealed high turnover numbers (kcat of 147.9 s-1 and 0.64 s-1, respectively). Surprisingly, when combined, AfCel6A and AfAA9_B did not act synergistically. AfCel6A and AfAA9_B association inhibited AfCel6A activity, an outcome that needs to be further investigated. However, AfCel6A or AfAA9_B addition boosted the enzymatic saccharification activity of a cellulase cocktail and the activity of cellulase Af-EGL7. Enzymatic cocktail supplementation with AfCel6A or AfAA9_B boosted the yield of fermentable sugars from complex substrates, especially sugarcane exploded bagasse, by up to 95%. The synergism between the cellulase cocktail and AfAA9_B was enzyme- and substrate-specific, which suggests a specific enzymatic cocktail for each biomass by up to 95%. The synergism between the cellulase cocktail and AfAA9_B was enzyme- and substrate-specific, which suggests a specific enzymatic cocktail for each biomass.
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Affiliation(s)
- Aline Vianna Bernardi
- Faculdade de Filosofia Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto 14040-901, Brazil; (A.V.B.); (L.E.G.); (P.F.d.G.); (D.K.Y.); (L.M.S.P.); (A.H.C.d.O.)
| | - Luis Eduardo Gerolamo
- Faculdade de Filosofia Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto 14040-901, Brazil; (A.V.B.); (L.E.G.); (P.F.d.G.); (D.K.Y.); (L.M.S.P.); (A.H.C.d.O.)
| | - Paula Fagundes de Gouvêa
- Faculdade de Filosofia Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto 14040-901, Brazil; (A.V.B.); (L.E.G.); (P.F.d.G.); (D.K.Y.); (L.M.S.P.); (A.H.C.d.O.)
| | - Deborah Kimie Yonamine
- Faculdade de Filosofia Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto 14040-901, Brazil; (A.V.B.); (L.E.G.); (P.F.d.G.); (D.K.Y.); (L.M.S.P.); (A.H.C.d.O.)
| | - Lucas Matheus Soares Pereira
- Faculdade de Filosofia Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto 14040-901, Brazil; (A.V.B.); (L.E.G.); (P.F.d.G.); (D.K.Y.); (L.M.S.P.); (A.H.C.d.O.)
| | - Arthur Henrique Cavalcante de Oliveira
- Faculdade de Filosofia Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto 14040-901, Brazil; (A.V.B.); (L.E.G.); (P.F.d.G.); (D.K.Y.); (L.M.S.P.); (A.H.C.d.O.)
| | - Sérgio Akira Uyemura
- Faculdade de Ciências Farmacêuticas de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto 14040-903, Brazil;
| | - Taisa Magnani Dinamarco
- Faculdade de Filosofia Ciências e Letras de Ribeirão Preto, Universidade de São Paulo, Ribeirão Preto 14040-901, Brazil; (A.V.B.); (L.E.G.); (P.F.d.G.); (D.K.Y.); (L.M.S.P.); (A.H.C.d.O.)
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16
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A steady-state approach for inhibition of heterogeneous enzyme reactions. Biochem J 2020; 477:1971-1982. [PMID: 32391552 DOI: 10.1042/bcj20200083] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2020] [Revised: 05/07/2020] [Accepted: 05/11/2020] [Indexed: 02/02/2023]
Abstract
The kinetic theory of enzymes that modify insoluble substrates is still underdeveloped, despite the prevalence of this type of reaction both in vivo and industrial applications. Here, we present a steady-state kinetic approach to investigate inhibition occurring at the solid-liquid interface. We propose to conduct experiments under enzyme excess (E0 ≫ S0), i.e. the opposite limit compared with the conventional Michaelis-Menten framework. This inverse condition is practical for insoluble substrates and elucidates how the inhibitor reduces enzyme activity through binding to the substrate. We claim that this type of inhibition is common for interfacial enzyme reactions because substrate accessibility is low, and we show that it can be analyzed by experiments and rate equations that are analogous to the conventional approach, except that the roles of enzyme and substrate have been swapped. To illustrate the approach, we investigated the major cellulases from Trichoderma reesei (Cel6A and Cel7A) acting on insoluble cellulose. As model inhibitors, we used catalytically inactive variants of Cel6A and Cel7A. We made so-called inverse Michaelis-Menten curves at different concentrations of inhibitors and found that a new rate equation accounted well for the data. In most cases, we found a mixed type of surface-site inhibition mechanism, and this probably reflected that the inhibitor both competed with the enzyme for the productive binding-sites (competitive inhibition) and hampered the processive movement on the surface (uncompetitive inhibition). These results give new insights into the complex interplay of Cel7A and Cel6A on cellulose and the approach may be applicable to other heterogeneous enzyme reactions.
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17
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Sreeja-Raju A, Christopher M, Kooloth-Valappil P, Kuni-Parambil R, Gokhale DV, Sankar M, Abraham A, Pandey A, Sukumaran RK. Penicillium janthinellum NCIM1366 shows improved biomass hydrolysis and a larger number of CAZymes with higher induction levels over Trichoderma reesei RUT-C30. BIOTECHNOLOGY FOR BIOFUELS 2020; 13:196. [PMID: 33292411 PMCID: PMC7706291 DOI: 10.1186/s13068-020-01830-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Accepted: 11/16/2020] [Indexed: 05/09/2023]
Abstract
BACKGROUND Major cost of bioethanol is attributed to enzymes employed in biomass hydrolysis. Biomass hydrolyzing enzymes are predominantly produced from the hyper-cellulolytic mutant filamentous fungus Trichoderma reesei RUT-C30. Several decades of research have failed to provide an industrial grade organism other than T. reesei, capable of producing higher titers of an effective synergistic biomass hydrolyzing enzyme cocktail. Penicillium janthinellum NCIM1366 was reported as a cellulase hyper producer and a potential alternative to T. reesei, but a comparison of their hydrolytic performance was seldom attempted. RESULTS Hydrolysis of acid or alkali-pretreated rice straw using cellulase enzyme preparations from P. janthinellum and T. reesei indicated 37 and 43% higher glucose release, respectively, with P. janthinellum enzymes. A comparison of these fungi with respect to their secreted enzymes indicated that the crude enzyme preparation from P. janthinellum showed 28% higher overall cellulase activity. It also had an exceptional tenfold higher beta-glucosidase activity compared to that of T. reesei, leading to a lower cellobiose accumulation and thus alleviating the feedback inhibition. P. janthinellum secreted more number of proteins to the extracellular medium whose total concentration was 1.8-fold higher than T. reesei. Secretome analyses of the two fungi revealed higher number of CAZymes and a higher relative abundance of cellulases upon cellulose induction in the fungus. CONCLUSIONS The results revealed the ability of P. janthinellum for efficient biomass degradation through hyper cellulase production, and it outperformed the established industrial cellulase producer T. reesei in the hydrolysis experiments. A higher level of induction, larger number of secreted CAZymes and a high relative proportion of BGL to cellulases indicate the possible reasons for its performance advantage in biomass hydrolysis.
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Affiliation(s)
- AthiraRaj Sreeja-Raju
- Biofuels and Biorefineries Section, Microbial Processes and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology, Industrial Estate, Pappanamcode, Thiruvananthapuram, 695019, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Meera Christopher
- Biofuels and Biorefineries Section, Microbial Processes and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology, Industrial Estate, Pappanamcode, Thiruvananthapuram, 695019, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Prajeesh Kooloth-Valappil
- Biofuels and Biorefineries Section, Microbial Processes and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology, Industrial Estate, Pappanamcode, Thiruvananthapuram, 695019, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Rajasree Kuni-Parambil
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore, 560012, India
| | | | - Meena Sankar
- Biofuels and Biorefineries Section, Microbial Processes and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology, Industrial Estate, Pappanamcode, Thiruvananthapuram, 695019, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India
| | - Amith Abraham
- Department of Chemical Engineering, Hanyang University, Seoul, Republic of Korea
| | - Ashok Pandey
- Centre for Innovation and Translational Research, CSIR-Indian Institute of Toxicology Research, Lucknow, India
| | - Rajeev K Sukumaran
- Biofuels and Biorefineries Section, Microbial Processes and Technology Division, CSIR-National Institute for Interdisciplinary Science and Technology, Industrial Estate, Pappanamcode, Thiruvananthapuram, 695019, India.
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad, 201002, India.
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18
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Bermejo PM, Raghavendran V, Gombert AK. Neither 1G nor 2G fuel ethanol: setting the ground for a sugarcane-based biorefinery using an iSUCCELL yeast platform. FEMS Yeast Res 2020; 20:5836716. [PMID: 32401320 DOI: 10.1093/femsyr/foaa027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2020] [Accepted: 05/11/2020] [Indexed: 11/12/2022] Open
Abstract
First-generation (1G) fuel ethanol production in sugarcane-based biorefineries is an established economic enterprise in Brazil. Second-generation (2G) fuel ethanol from lignocellulosic materials, though extensively investigated, is currently facing severe difficulties to become economically viable. Some of the challenges inherent to these processes could be resolved by efficiently separating and partially hydrolysing the cellulosic fraction of the lignocellulosic materials into the disaccharide cellobiose. Here, we propose an alternative biorefinery, where the sucrose-rich stream from the 1G process is mixed with a cellobiose-rich stream in the fermentation step. The advantages of mixing are 3-fold: (i) decreased concentrations of metabolic inhibitors that are typically produced during pretreatment and hydrolysis of lignocellulosic materials; (ii) decreased cooling times after enzymatic hydrolysis prior to fermentation; and (iii) decreased availability of free glucose for contaminating microorganisms and undesired glucose repression effects. The iSUCCELL platform will be built upon the robust Saccharomyces cerevisiae strains currently present in 1G biorefineries, which offer competitive advantage in non-aseptic environments, and into which intracellular hydrolyses of sucrose and cellobiose will be engineered. It is expected that high yields of ethanol can be achieved in a process with cell recycling, lower contamination levels and decreased antibiotic use, when compared to current 2G technologies.
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Affiliation(s)
| | - Vijayendran Raghavendran
- Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK
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19
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Molecular recognition in the product site of cellobiohydrolase Cel7A regulates processive step length. Biochem J 2020; 477:99-110. [PMID: 31816027 DOI: 10.1042/bcj20190770] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Revised: 12/06/2019] [Accepted: 12/09/2019] [Indexed: 11/17/2022]
Abstract
Cellobiohydrolase Cel7A is an industrial important enzyme that breaks down cellulose by a complex processive mechanism. The enzyme threads the reducing end of a cellulose strand into its tunnel-shaped catalytic domain and progresses along the strand while sequentially releasing the disaccharide cellobiose. While some molecular details of this intricate process have emerged, general structure-function relationships for Cel7A remain poorly elucidated. One interesting aspect is the occurrence of particularly strong ligand interactions in the product binding site. In this work, we analyze these interactions in Cel7A from Trichoderma reesei with special emphasis on the Arg251 and Arg394 residues. We made extensive biochemical characterization of enzymes that were mutated in these two positions and showed that the arginine residues contributed strongly to product binding. Specifically, ∼50% of the total standard free energy of product binding could be ascribed to four hydrogen bonds to Arg251 and Arg394, which had previously been identified in crystal structures. Mutation of either Arg251 or Arg394 lowered production inhibition of Cel7A, but at the same time altered the enzyme product profile and resulted in ∼50% reduction in both processivity and hydrolytic activity. The position of the two arginine residues closely matches the two-fold screw axis symmetry of the substrate, and this energetically favors the productive enzyme-substrate complex. Our results indicate that the strong and specific ligand interactions of Arg251 and Arg394 provide a simple proofreading system that controls the step length during consecutive hydrolysis and minimizes dead time associated with transient, non-productive complexes.
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20
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Xu C, Zhang J, Zhang Y, Guo Y, Xu H, Xu J, Wang Z. Enhancement of high-solids enzymatic hydrolysis efficiency of alkali pretreated sugarcane bagasse at low cellulase dosage by fed-batch strategy based on optimized accessory enzymes and additives. BIORESOURCE TECHNOLOGY 2019; 292:121993. [PMID: 31442837 DOI: 10.1016/j.biortech.2019.121993] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Revised: 08/08/2019] [Accepted: 08/09/2019] [Indexed: 06/10/2023]
Abstract
Obtaining higher amount of final sugars with low cellulase dosage has great economic benefits for the industrial biorefinery of lignocellulosic biomass. The optimization of accessory enzymes and additives were performed using single factor and orthogonal experiment firstly, after that, fed-batch strategy was applied to enhance the high-solids enzymatic hydrolysis efficiency of alkali pretreated sugarcane bagasse (SCB). A novel enzymatic hydrolysis procedure with 22% (w/v) substrate content and cellulase dosage of only 4 FPU/g dry biomass (DM) was developed, after digested for 48 h, the achieved glucose titer, yield and productivity were 122 g/L, 80% and 2.54 g L-1 h-1, respectively. Results obtained in this study indicated a potential finding for the industrial application of lignocellulosic biomass.
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Affiliation(s)
- Chao Xu
- Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou 510640, China; CAS Key Laboratory of Renewable Energy, Guangzhou 510640, China; Guangdong Provincial Key Laboratory of New and Renewable Energy Research and Development, Guangzhou 510640, China; University of China Academy of Sciences, Beijing 100049, China
| | - Jun Zhang
- Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou 510640, China; CAS Key Laboratory of Renewable Energy, Guangzhou 510640, China; Guangdong Provincial Key Laboratory of New and Renewable Energy Research and Development, Guangzhou 510640, China; University of China Academy of Sciences, Beijing 100049, China
| | - Yu Zhang
- Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou 510640, China
| | - Ying Guo
- Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou 510640, China
| | - Huijuan Xu
- Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou 510640, China
| | - Jingliang Xu
- Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou 510640, China; School of Chemical Engineering, Zhengzhou University, Zhengzhou 450001, China.
| | - Zhongming Wang
- Guangzhou Institute of Energy Conversion, Chinese Academy of Sciences, Guangzhou 510640, China
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21
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Zong Z, Li Q, Hong Z, Fu H, Cai W, Chipot C, Jiang H, Zhang D, Chen S, Shao X. Lysine Mutation of the Claw-Arm-Like Loop Accelerates Catalysis by Cellobiohydrolases. J Am Chem Soc 2019; 141:14451-14459. [DOI: 10.1021/jacs.9b08477] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Zhiyou Zong
- State Key Laboratory of Medicinal Chemical Biology, Tianjin Key Laboratory of Biosensing and Molecular Recognition, Research Center for Analytical Sciences, College of Chemistry, Nankai University, Tianjin 300071, P. R. China
| | - Qiyu Li
- State Key Laboratory of Medicinal Chemical Biology, Tianjin Key Laboratory of Biosensing and Molecular Recognition, Research Center for Analytical Sciences, College of Chemistry, Nankai University, Tianjin 300071, P. R. China
| | - Zhangyong Hong
- State Key Laboratory of Medicinal Chemical Biology, Tianjin Key Laboratory of Biosensing and Molecular Recognition, Research Center for Analytical Sciences, College of Chemistry, Nankai University, Tianjin 300071, P. R. China
| | - Haohao Fu
- State Key Laboratory of Medicinal Chemical Biology, Tianjin Key Laboratory of Biosensing and Molecular Recognition, Research Center for Analytical Sciences, College of Chemistry, Nankai University, Tianjin 300071, P. R. China
| | - Wensheng Cai
- State Key Laboratory of Medicinal Chemical Biology, Tianjin Key Laboratory of Biosensing and Molecular Recognition, Research Center for Analytical Sciences, College of Chemistry, Nankai University, Tianjin 300071, P. R. China
| | - Christophe Chipot
- Laboratoire International Associé CNRS and University of Illinois at Urbana—Champaign, LPCT, UMR 7019 Universiteé de Lorraine CNRS, Vandœuvre-lès-Nancy F-54500, France
- Department of Physics, University of Illinois at Urbana—Champaign, Urbana, Illinois 61801, United States
| | - Huifeng Jiang
- Key Laboratory of Systems Microbial Biotechnology, Tianjin Key Laboratory for Industrial Biological Systems and Bioprocessing Engineering, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, P. R. China
| | - Dongyuan Zhang
- Key Laboratory of Systems Microbial Biotechnology, Tianjin Key Laboratory for Industrial Biological Systems and Bioprocessing Engineering, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, P. R. China
| | - Shulin Chen
- Key Laboratory of Systems Microbial Biotechnology, Tianjin Key Laboratory for Industrial Biological Systems and Bioprocessing Engineering, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, P. R. China
| | - Xueguang Shao
- State Key Laboratory of Medicinal Chemical Biology, Tianjin Key Laboratory of Biosensing and Molecular Recognition, Research Center for Analytical Sciences, College of Chemistry, Nankai University, Tianjin 300071, P. R. China
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22
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Ying H, Wang J, Shi T, Zhao Y, Ouyang P, Chen K. Engineering of lysine cyclodeaminase conformational dynamics for relieving substrate and product inhibitions in the biosynthesis of l-pipecolic acid. Catal Sci Technol 2019. [DOI: 10.1039/c8cy02301h] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Efficient biocatalytic process construction by relieving substrate and product inhibitions via identification and engineering of enzyme conformational dynamics.
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Affiliation(s)
- Hanxiao Ying
- College of Biotechnology and Pharmaceutical Engineering
- Nanjing Tech University
- Nanjing
- China
| | - Jing Wang
- College of Biotechnology and Pharmaceutical Engineering
- Nanjing Tech University
- Nanjing
- China
| | - Ting Shi
- School of Life Sciences and Biotechnology
- Shanghai Jiaotong University
- Shanghai
- China
| | - Yilei Zhao
- School of Life Sciences and Biotechnology
- Shanghai Jiaotong University
- Shanghai
- China
| | - Pingkai Ouyang
- College of Biotechnology and Pharmaceutical Engineering
- Nanjing Tech University
- Nanjing
- China
| | - Kequan Chen
- College of Biotechnology and Pharmaceutical Engineering
- Nanjing Tech University
- Nanjing
- China
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23
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Lu X, Feng X, Li X, Zhao J. Binding and hydrolysis properties of engineered cellobiohydrolases and endoglucanases. BIORESOURCE TECHNOLOGY 2018; 267:235-241. [PMID: 30025319 DOI: 10.1016/j.biortech.2018.06.047] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2018] [Revised: 06/14/2018] [Accepted: 06/17/2018] [Indexed: 05/03/2023]
Abstract
Because cellulase was the main enzyme used in bioconversion of lignocellulose, it was a valid way to reduce the hydrolysis cost by increasing the adsorption and hydrolysis efficiency of cellulase. In this study, modified cellobiohydrolases (CBHs) and endoglucanases (EGs) were constructed. Two engineered cellulases CBH-TrCBMV27E,P30D,Link1 and EG-TrCBMV27E,P30D,Link1 well-performed during hydrolysis. Compared to wild-type enzymes, EG-TrCBMV27E,P30D,Link1 had relatively less adsorption ability to lignin and greater affinity to cellulose, especially Avicel. However, for CBH-TrCBMV27E,P30D,Link1, the hydrolysis manner was changed and in favor to hydrolysis process, although the adsorption properties were unexpected. It suggested that various binding conformations of polysaccharide on CBMs hypothetically resulted in different functions of CBMs, including binding ability, processive and digestive properties on fiber surface. Fusion of T. r-CBMV27E,P30D,Link1 to cellulase, both CBH and EG, gave the destruction ability of enzyme and increased the accessible surface of substrate to cellulase, enhanced the adsorption and hydrolysis efficiency of cellulase.
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Affiliation(s)
- Xianqin Lu
- State Key Laboratory of Microbial Technology, Shandong University, No. 72, Binhai Road, Qingdao 266237, PR China
| | - Xiaoting Feng
- State Key Laboratory of Microbial Technology, Shandong University, No. 72, Binhai Road, Qingdao 266237, PR China
| | - Xuezhi Li
- State Key Laboratory of Microbial Technology, Shandong University, No. 72, Binhai Road, Qingdao 266237, PR China
| | - Jian Zhao
- State Key Laboratory of Microbial Technology, Shandong University, No. 72, Binhai Road, Qingdao 266237, PR China.
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Haldar D, Gayen K, Sen D. Enumeration of monosugars’ inhibition characteristics on the kinetics of enzymatic hydrolysis of cellulose. Process Biochem 2018. [DOI: 10.1016/j.procbio.2018.06.008] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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25
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Rabinovich ML, Melnik MS, Herner ML, Voznyi YV, Vasilchenko LG. Predominant Nonproductive Substrate Binding by Fungal Cellobiohydrolase I and Implications for Activity Improvement. Biotechnol J 2018; 14:e1700712. [PMID: 29781240 DOI: 10.1002/biot.201700712] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Revised: 05/08/2018] [Indexed: 12/20/2022]
Abstract
Enzymatic conversion of the most abundant renewable source of organic compounds, cellulose to fermentable sugars is attractive for production of green fuels and chemicals. The major component of industrial enzyme systems, cellobiohydrolase I from Hypocrea jecorina (Trichoderma reesei) (HjCel7A) processively splits disaccharide units from the reducing ends of tightly packed cellulose chains. HjCel7A consists of a catalytic domain (CD) and a carbohydrate-binding module (CBM) separated by a linker peptide. A tunnel-shaped substrate-binding site in the CD includes nine subsites for β-d-glucose units, seven of which (-7 to -1) precede the catalytic center. Low catalytic activity of Cel7A is the bottleneck and the primary target for improvement. Here it is shown for the first time that, in spite of much lower apparent kcat of HjCel7A at the hydrolysis of β-1,4-glucosidic linkages in the fluorogenic cellotetra- and -pentaose compared to the structurally related endoglucanase I (HjCel7B), the specificity constants (catalytic efficiency) kcat /Km for both enzymes are almost equal in these reactions. The observed activity difference appears from strong nonproductive substrate binding by HjCel7A, particularly significant for MU-β-cellotetraose (MUG4 ). Interaction of substrates with the subsites -6 and -5 proximal to the nonconserved Gln101 residue in HjCel7A decreases Km,ap by >1500 times. HjCel7A can be nonproductively bound onto cellulose surface with Kd ≈2-9 nM via CBM and CD that captures six terminal glucose units of cellulose chain. Decomposition of this nonproductive complex can determine the rate of cellulose conversion. MUG4 is a promising substrate to select active cellobiohydrolase I variants with reduced nonproductive substrate binding.
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Affiliation(s)
- Mikhail L Rabinovich
- Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, 33, bld. 2 Leninsky Ave., Moscow 119071, Russia
| | - Maria S Melnik
- Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, 33, bld. 2 Leninsky Ave., Moscow 119071, Russia
| | - Mikhail L Herner
- Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, 33, bld. 2 Leninsky Ave., Moscow 119071, Russia
| | - Yakov V Voznyi
- Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Moscow 119991, Russia
| | - Lilia G Vasilchenko
- Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, 33, bld. 2 Leninsky Ave., Moscow 119071, Russia
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26
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Zhai R, Hu J, Saddler JN. The inhibition of hemicellulosic sugars on cellulose hydrolysis are highly dependant on the cellulase productive binding, processivity, and substrate surface charges. BIORESOURCE TECHNOLOGY 2018; 258:79-87. [PMID: 29524690 DOI: 10.1016/j.biortech.2017.12.006] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2017] [Revised: 12/02/2017] [Accepted: 12/04/2017] [Indexed: 05/24/2023]
Abstract
In this study, the influence of major hemicellulosic sugars (mannose and xylose) on cellulose hydrolysis and major enzyme activities were evaluated by using both commercial enzyme cocktail and purified cellulase monocomponents over a "library" of cellulosic substrates. Surprisingly, the results showed that unlike glucose, mannose/xylose did not inhibit individual cellulase activities but significantly decreased their hydrolytic performance on cellulose substrates. When various enzyme-substrate interactions (e.g. adsorption/desorption, productive binding, and processive moving) were evaluated, it appeared that these hemicellulosic sugars significantly reduced the productive binding and processivity of Cel7A, which in turn limited cellulase hydrolytic efficacy. Among a range of major cellulose characteristics (e.g. crystallinity, degree of polymerization, accessibility, and surface charges), the acid group content of the cellulosic substrates seemed to be the main driver that determined the extent of hemicellulosic sugar inhibition. Our results provided new insights for better understanding the sugar inhibition mechanisms of cellulose hydrolysis.
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Affiliation(s)
- Rui Zhai
- School of Environmental and Biological Engineering, Nanjing University of Science and Technology, 200 Xiaolingwei Street, Nanjing 210094, China; Forest Products Biotechnology and Bioenergy Group, Department of Wood Science, Faculty of Forestry, The University of British Columbia, 2424 Main Mall, Vancouver, BC, Canada
| | - Jinguang Hu
- Forest Products Biotechnology and Bioenergy Group, Department of Wood Science, Faculty of Forestry, The University of British Columbia, 2424 Main Mall, Vancouver, BC, Canada.
| | - Jack N Saddler
- Forest Products Biotechnology and Bioenergy Group, Department of Wood Science, Faculty of Forestry, The University of British Columbia, 2424 Main Mall, Vancouver, BC, Canada
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Brandenburg J, Poppele I, Blomqvist J, Puke M, Pickova J, Sandgren M, Rapoport A, Vedernikovs N, Passoth V. Bioethanol and lipid production from the enzymatic hydrolysate of wheat straw after furfural extraction. Appl Microbiol Biotechnol 2018; 102:6269-6277. [PMID: 29804136 PMCID: PMC6013517 DOI: 10.1007/s00253-018-9081-7] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 05/12/2018] [Indexed: 12/16/2022]
Abstract
This study investigates biofuel production from wheat straw hydrolysate, from which furfural was extracted using a patented method developed at the Latvian State Institute of Wood Chemistry. The solid remainder after furfural extraction, corresponding to 67.6% of the wheat straw dry matter, contained 69.9% cellulose of which 4% was decomposed during the furfural extraction and 26.3% lignin. Enzymatic hydrolysis released 44% of the glucose monomers in the cellulose. The resulting hydrolysate contained mainly glucose and very little amount of acetic acid. Xylose was not detectable. Consequently, the undiluted hydrolysate did not inhibit growth of yeast strains belonging to Saccharomyces cerevisiae, Lipomyces starkeyi, and Rhodotorula babjevae. In the fermentations, average final ethanol concentrations of 23.85 g/l were obtained, corresponding to a yield of 0.53 g ethanol per g released glucose. L. starkeyi generated lipids with a rate of 0.08 g/h and a yield of 0.09 g per g consumed glucose. R. babjevae produced lipids with a rate of 0.18 g/h and a yield of 0.17 per g consumed glucose. In both yeasts, desaturation increased during cultivation. Remarkably, the R. babjevae strain used in this study produced considerable amounts of heptadecenoic, α,- and γ-linolenic acid.
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Affiliation(s)
- Jule Brandenburg
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, P.O.-Box 7015, S-75007, Uppsala, Sweden
| | - Ieva Poppele
- Institute of Microbiology and Biotechnology, University of Latvia, Jelgavas Str., 1-537, Riga, LV-1004, Latvia
| | - Johanna Blomqvist
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, P.O.-Box 7015, S-75007, Uppsala, Sweden
| | - Maris Puke
- Latvian State Institute of Wood Chemistry, Dzerbenes Str. 27/345, Riga, LV-1006, Latvia
| | - Jana Pickova
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, P.O.-Box 7015, S-75007, Uppsala, Sweden
| | - Mats Sandgren
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, P.O.-Box 7015, S-75007, Uppsala, Sweden
| | - Alexander Rapoport
- Institute of Microbiology and Biotechnology, University of Latvia, Jelgavas Str., 1-537, Riga, LV-1004, Latvia
| | - Nikolajs Vedernikovs
- Latvian State Institute of Wood Chemistry, Dzerbenes Str. 27/345, Riga, LV-1006, Latvia
| | - Volkmar Passoth
- Department of Molecular Sciences, Swedish University of Agricultural Sciences, P.O.-Box 7015, S-75007, Uppsala, Sweden.
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28
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Silveira RL, Skaf MS. Concerted motions and large-scale structural fluctuations of Trichoderma reesei Cel7A cellobiohydrolase. Phys Chem Chem Phys 2018; 20:7498-7507. [PMID: 29488531 DOI: 10.1039/c8cp00101d] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Cellobiohydrolases (CBHs) are key enzymes for the saccharification of cellulose and play major roles in industrial settings for biofuel production. The catalytic core domain of these enzymes exhibits a long and narrow binding tunnel capable of binding glucan chains from crystalline cellulose and processively hydrolyze them. The binding cleft is topped by a set of loops, which are believed to play key roles in substrate binding and cleavage processivity. Here, we present an analysis of the loop motions of the Trichoderma reesei Cel7A catalytic core domain (TrCel7A) using conventional and accelerated molecular dynamics simulations. We observe that the loops exhibit highly coupled fluctuations and cannot move independently of each other. In the absence of a substrate, the characteristic large amplitude dynamics of TrCel7A consists of breathing motions, where the loops undergo open-and-close fluctuations. Upon substrate binding, the open-close fluctuations of the loops are quenched and one of the loops moves parallel to the binding site, possibly to allow processive motion along the glucan chain. Using microsecond accelerated molecular dynamics, we observe large-scale fluctuations of the loops (up to 37 Å) and the entire exposure of the TrCel7A binding site in the absence of the substrate, resembling an endoglucanase. These results suggest that the initial CBH-substrate contact and substrate recognition by the enzyme are similar to that of endoglucanases and, once bound to the substrate, the loops remain closed for proper enzymatic activity.
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Affiliation(s)
- Rodrigo L Silveira
- Institute of Chemistry, University of Campinas, Cx. P. 6154, Campinas, 13084-862, SP, Brazil.
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29
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Kari J, Kont R, Borch K, Buskov S, Olsen JP, Cruyz-Bagger N, Väljamäe P, Westh P. Anomeric Selectivity and Product Profile of a Processive Cellulase. Biochemistry 2016; 56:167-178. [PMID: 28026938 DOI: 10.1021/acs.biochem.6b00636] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Cellobiohydrolases (CBHs) make up an important group of enzymes for both natural carbon cycling and industrial deconstruction of lignocellulosic biomass. The consecutive hydrolysis of one cellulose strand relies on an intricate pattern of enzyme-substrate interactions in the long, tunnel-shaped binding site of the CBH. In this work, we have investigated the initial complexation mode with cellulose of the most thoroughly studied CBH, Cel7A from Hypocrea jecorina (HjCel7A). We found that HjCel7A predominantly produces glucose when it initiates a processive run on insoluble microcrystalline cellulose, confirming the validity of an even and odd product ratio as an estimate of processivity. Moreover, the glucose released from cellulose was predominantly α-glucose. A link between the initial binding mode of the enzyme and the reducing end configuration was investigated by inhibition studies with the two anomers of cellobiose. A clear preference for β-cellobiose in product binding site +2 was observed for HjCel7A, but not the homologous endoglucanase, HjCe7B. Possible relationships between this anomeric preference in the product site and the prevalence of odd-numbered initial-cut products are discussed, and a correlation between processivity and anomer selectivity is proposed.
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Affiliation(s)
- Jeppe Kari
- Research Unit for Functional Biomaterials, Roskilde University , Roskilde, Denmark
| | - Riin Kont
- Institute of Molecular and Cell Biology, University of Tartu , Tartu, Estonia
| | - Kim Borch
- Novozymes A/S , Krogshøjvej 36, DK-2880 Bagsværd, Denmark
| | - Steen Buskov
- Novozymes A/S , Krogshøjvej 36, DK-2880 Bagsværd, Denmark
| | - Johan Pelck Olsen
- Research Unit for Functional Biomaterials, Roskilde University , Roskilde, Denmark
| | | | - Priit Väljamäe
- Institute of Molecular and Cell Biology, University of Tartu , Tartu, Estonia
| | - Peter Westh
- Research Unit for Functional Biomaterials, Roskilde University , Roskilde, Denmark
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30
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Han SS, Kyeong HH, Choi JM, Sohn YK, Lee JH, Kim HS. Engineering of the Conformational Dynamics of an Enzyme for Relieving the Product Inhibition. ACS Catal 2016. [DOI: 10.1021/acscatal.6b02793] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Affiliation(s)
- Sang-Soo Han
- Department
of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Korea
| | - Hyun-Ho Kyeong
- Department
of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Korea
| | - Jung Min Choi
- Department
of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Korea
| | - Yoo-Kyoung Sohn
- Department
of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Korea
| | - Jin-Ho Lee
- Department
of Food Science and Biotechnology, Kyungsung University, 309, Suyeong-ro, Nam-gu, Busan 48434, Korea
| | - Hak-Sung Kim
- Department
of Biological Sciences, Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 34141, Korea
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31
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Crystal structures of wild‐type
Trichoderma reesei
Cel7A catalytic domain in open and closed states. FEBS Lett 2016; 590:4429-4438. [DOI: 10.1002/1873-3468.12464] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2016] [Revised: 10/03/2016] [Accepted: 10/10/2016] [Indexed: 11/07/2022]
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32
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Chen M, Bu L, Alahuhta M, Brunecky R, Xu Q, Lunin VV, Brady JW, Crowley MF, Himmel ME, Bomble YJ. Strategies to reduce end-product inhibition in family 48 glycoside hydrolases. Proteins 2016; 84:295-304. [PMID: 26572060 DOI: 10.1002/prot.24965] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2015] [Revised: 10/02/2015] [Accepted: 11/06/2015] [Indexed: 11/07/2022]
Abstract
Family 48 cellobiohydrolases are some of the most abundant glycoside hydrolases in nature. They are able to degrade cellulosic biomass and therefore serve as good enzyme candidates for biofuel production. Family 48 cellulases hydrolyze cellulose chains via a processive mechanism, and produce end products composed primarily of cellobiose as well as other cellooligomers (dp ≤ 4). The challenge of utilizing cellulases in biofuel production lies in their extremely slow turnover rate. A factor contributing to the low enzyme activity is suggested to be product binding to enzyme and the resulting performance inhibition. In this study, we quantitatively evaluated the product inhibitory effect of four family 48 glycoside hydrolases using molecular dynamics simulations and product expulsion free-energy calculations. We also suggested a series of single mutants of the four family 48 glycoside hydrolases with theoretically reduced level of product inhibition. The theoretical calculations provide a guide for future experimental studies designed to produce mutant cellulases with enhanced activity.
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Affiliation(s)
- Mo Chen
- Department of Food Science, Cornell University, Ithaca, New York
| | - Lintao Bu
- National Renewable Energy Laboratory, Golden, Colorado
| | | | | | - Qi Xu
- National Renewable Energy Laboratory, Golden, Colorado
| | | | - John W Brady
- Department of Food Science, Cornell University, Ithaca, New York
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Olsen JP, Alasepp K, Kari J, Cruys-Bagger N, Borch K, Westh P. Mechanism of product inhibition for cellobiohydrolase Cel7A during hydrolysis of insoluble cellulose. Biotechnol Bioeng 2016; 113:1178-86. [DOI: 10.1002/bit.25900] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Revised: 11/23/2015] [Accepted: 11/29/2015] [Indexed: 01/10/2023]
Affiliation(s)
- Johan P. Olsen
- Research Unit for Functional Biomaterials; Roskilde University; NSM, 1 Universitetsvej, Build. 28 DK-4000 Roskilde Denmark
| | - Kadri Alasepp
- Research Unit for Functional Biomaterials; Roskilde University; NSM, 1 Universitetsvej, Build. 28 DK-4000 Roskilde Denmark
| | - Jeppe Kari
- Research Unit for Functional Biomaterials; Roskilde University; NSM, 1 Universitetsvej, Build. 28 DK-4000 Roskilde Denmark
| | - Nicolaj Cruys-Bagger
- Research Unit for Functional Biomaterials; Roskilde University; NSM, 1 Universitetsvej, Build. 28 DK-4000 Roskilde Denmark
- Novozymes A/S; Bagsvaerd Denmark
| | | | - Peter Westh
- Research Unit for Functional Biomaterials; Roskilde University; NSM, 1 Universitetsvej, Build. 28 DK-4000 Roskilde Denmark
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