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Joshi N, Kaushal G, Singh SP. Biochemical characterization of a novel thermo-halo-tolerant GH5 endoglucanase from a thermal spring metagenome. Biotechnol Bioeng 2021; 118:1531-1544. [PMID: 33410140 DOI: 10.1002/bit.27668] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 01/01/2021] [Accepted: 01/03/2021] [Indexed: 12/31/2022]
Abstract
A novel endoglucanase gene, celM , was cloned from a thermal spring metagenome. The gene was expressed in Escherichia coli, and the protein was extracted and purified. The protein catalyzed the hydrolysis of amorphous cellulose in a wide range of temperatures, 30-95°C, with optimal activity at 80°C. It was able to tolerate high temperature (80°C) with a half-life of 8 h. Its activity was eminent in a wide pH range of 3.0-11.0, with the highest activity at pH 6.0. The enzyme was tested for halostability. Any significant loss was not recorded in the activity of CelM after the exposure to salinity (3 M NaCl) for 30 days. Furthermore, CelM displayed a substantial resistance toward metal ions, denaturant, reducing agent, organic solvent, and non-ionic surfactants. The amorphous cellulose, treated with CelM , was randomly cleaved, generating cello-oligosaccharides of 2-5 degree of polymerization. Furthermore, CelM was demonstrated to catalyze the hydrolysis of cellulose fraction in the delignified biomass samples, for example, sweet sorghum bagasse, rice straw, and corncob, into cello-oligosaccharides. Given that CelM is a thermo-halo-tolerant GH5 endoglucanase, with resistance to detergents and organic solvent, the biocatalyst could be of potential usefulness for a variety of industrial applications.
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Affiliation(s)
- Namrata Joshi
- Center of Innovative and Applied Bioprocessing (DBT-CIAB), Mohali, Punjab, India
| | - Girija Kaushal
- Center of Innovative and Applied Bioprocessing (DBT-CIAB), Mohali, Punjab, India
| | - Sudhir P Singh
- Center of Innovative and Applied Bioprocessing (DBT-CIAB), Mohali, Punjab, India
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2
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Singh S, Kumar K, Nath P, Goyal A. Role of glycine 256 residue in improving the catalytic efficiency of mutant endoglucanase of family 5 glycoside hydrolase from Bacillus amyloliquefaciens SS35. Biotechnol Bioeng 2020; 117:2668-2682. [PMID: 32484905 DOI: 10.1002/bit.27448] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2020] [Revised: 05/24/2020] [Accepted: 05/31/2020] [Indexed: 11/07/2022]
Abstract
Wild-type, BaGH5-WT and mutant, BaGH5-UV2 (aspartate residue mutated to glycine), endoglucanases belonging to glycoside hydrolase family 5 (GH5), from wild-type, and UV2 mutant strain of Bacillus amyloliquefaciens SS35, respectively, were earlier cloned in pHTP0 cloning vector. In this study, genes encoding BaGH5-WT or BaGH5-UV2 were cloned into pET28a(+) expression-vector and expressed in Escherichia coli BL-21(DE3)pLysS cells. BaGH5-UV2 showed 10-fold (43.6 U/mg) higher specific activity against carboxymethylcellulose sodium salt (CMC-Na), higher optimal temperature by 10°C at 65°C, and 22-fold higher catalytic efficiency against CMC-Na, than BaGH5-WT. BaGH5-UV2 showed stability in wider acidic pH range (5.0-7.0) unlike BaGH5-WT in narrow basic pH range (7.0-7.5). BaGH5-UV2 displayed a mutation, Asp256Gly in L11 loop, connecting β6 -sheet with α6 -helix, near active site toward the domain surface of (α/β)8 -TIM barrel fold. Molecular dynamics simulation studies showed more stable structure, accessibility of substrate for a catalytic site, and increased flexibility of loop L11 of BaGH5-UV2 than the wild type, suggesting enhanced catalysis by BaGH5-UV2. Molecular docking analysis displayed enhanced hydrogen bond interactions of cello-oligosaccharides with BaGH5-UV2, unlike BaGH5-WT. Thus, Gly256 residue of loop L11 plays an important role in enhancing catalytic efficiency, and pH stability of GH5 endoglucanase. Therefore, these results help in protein engineering of GH5 endoglucanase for improved biochemical properties.
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Affiliation(s)
- Shweta Singh
- Carbohydrate Enzyme Biotechnology Laboratory, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, Assam, India.,DBT PAN-IIT Centre for Bioenergy, Indian Institute of Technology Guwahati, Guwahati, Assam, India
| | - Krishan Kumar
- Carbohydrate Enzyme Biotechnology Laboratory, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, Assam, India
| | - Priyanka Nath
- Carbohydrate Enzyme Biotechnology Laboratory, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, Assam, India.,DBT PAN-IIT Centre for Bioenergy, Indian Institute of Technology Guwahati, Guwahati, Assam, India
| | - Arun Goyal
- Carbohydrate Enzyme Biotechnology Laboratory, Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati, Assam, India.,DBT PAN-IIT Centre for Bioenergy, Indian Institute of Technology Guwahati, Guwahati, Assam, India
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3
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Konar S, Sinha SK, Datta S, Ghorai PK. Probing the Effect of Glucose on the Activity and Stability of β-Glucosidase: An All-Atom Molecular Dynamics Simulation Investigation. ACS OMEGA 2019; 4:11189-11196. [PMID: 31460219 PMCID: PMC6648728 DOI: 10.1021/acsomega.9b00509] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2019] [Accepted: 06/10/2019] [Indexed: 05/11/2023]
Abstract
β-Glucosidase (EC 3.2.1.21) plays an essential role in the removal of glycosyl residues from disaccharide cellobiose to produce glucose during the hydrolysis of lignocellulosic biomass. Although there exist a few β-glucosidase that are tolerant to large concentrations of glucose, these enzymes are typically prone to glucose inhibition. Understanding the basis of this inhibition is important for the production of cheaper biofuels from lignocellulose. In this study, all-atom molecular dynamics simulation at different temperatures and glucose concentrations was used to understand the molecular basis of glucose inhibition of GH1 β-glucosidase (B8CYA8) from Halothermothrix orenii. Our results show that glucose induces a broadening of the active site tunnel through residues lining the tunnel and facilitates the accumulation of glucose. In particular, we observed that glucose accumulates at the tunnel entrance and near the catalytic sites to block substrate accessibility and inhibit enzyme activity. The reduction of enzyme activity was also confirmed experimentally through specific activity measurements in the presence of 0-2.5 M glucose. We also show that the increase in glucose concentrations leads to a decrease in the number of water molecules inside the tunnel to affect substrate hydrolysis. Overall, the results help in understanding the role of residues along the active site tunnel for the engineering of glucose-tolerant β-glucosidase.
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Affiliation(s)
- Sukanya Konar
- Department
of Chemical Sciences, Protein Engineering Laboratory, Department
of Biological Sciences, Centre for Advanced Functional Materials, and Centre for Climate
Change and Environmental Sciences, Indian
Institute of Science Education and Research Kolkata, Mohanpur 741246, India
| | - Sushant K. Sinha
- Department
of Chemical Sciences, Protein Engineering Laboratory, Department
of Biological Sciences, Centre for Advanced Functional Materials, and Centre for Climate
Change and Environmental Sciences, Indian
Institute of Science Education and Research Kolkata, Mohanpur 741246, India
| | - Supratim Datta
- Department
of Chemical Sciences, Protein Engineering Laboratory, Department
of Biological Sciences, Centre for Advanced Functional Materials, and Centre for Climate
Change and Environmental Sciences, Indian
Institute of Science Education and Research Kolkata, Mohanpur 741246, India
- E-mail: (S.D.)
| | - Pradip Kr. Ghorai
- Department
of Chemical Sciences, Protein Engineering Laboratory, Department
of Biological Sciences, Centre for Advanced Functional Materials, and Centre for Climate
Change and Environmental Sciences, Indian
Institute of Science Education and Research Kolkata, Mohanpur 741246, India
- E-mail: (P.K.G.)
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Zheng F, Tu T, Wang X, Wang Y, Ma R, Su X, Xie X, Yao B, Luo H. Enhancing the catalytic activity of a novel GH5 cellulase GtCel5 from Gloeophyllum trabeum CBS 900.73 by site-directed mutagenesis on loop 6. BIOTECHNOLOGY FOR BIOFUELS 2018; 11:76. [PMID: 29588661 PMCID: PMC5863444 DOI: 10.1186/s13068-018-1080-5] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Accepted: 03/14/2018] [Indexed: 05/17/2023]
Abstract
BACKGROUND Cellulases of glycosyl hydrolase (GH) family 5 share a (β/α)8 TIM-barrel fold structure with eight βα loops surrounding the catalytic pocket. These loops exposed on the surface play a vital role in protein functions, primarily due to the interactions of some key amino acids with solvent and ligand molecules. It has been reported that motions of these loops facilitate substrate access and product release, and loops 6 and 7 located at the substrate entrance of the binding pocket promote proton transfer reaction at the catalytic site motions. However, the role of these flexible loops in catalysis of GH5 cellulase remains to be explored. RESULTS In the present study, an acidic, mesophilic GH5 cellulase (with optimal activity at pH 4.0 and 70 °C), GtCel5, was identified in Gloeophyllum trabeum CBS 900.73. The specific activities of GtCel5 toward CMC-Na, barley β-glucan, and lichenan were 1117 ± 43, 6257 ± 26 and 5318 ± 54 U/mg, respectively. Multiple sequence alignment indicates that one amino acid residue at position 233 on the loop 6 shows semi-conservativeness and might contribute to the great catalytic performance. Saturation mutagenesis at position 233 was then conducted to reveal the vital roles of this position in enzyme properties. In comparison to the wild type, variants N233A and N233G showed decreased optimal temperature (- 10 °C) but increased activities (27 and 70%) and catalytic efficiencies (kcat/Km; 45 and 52%), respectively. The similar roles of position 233 in catalytic performance were also verified in the other two GH5 homologs, TeEgl5A and PoCel5, by reverse mutation. Further molecular dynamics simulations suggested that the substitution of asparagine with alanine or glycine may introduce more hydrogen bonds, increase the flexibility of loop 6, enhance the interactions between enzyme and substrate, and thus improve the substrate affinity and catalytic efficiency. CONCLUSION This study proposed a novel cellulase with potentials for industrial application. A specific position was identified to play key roles in cellulase-substrate interactions and enzyme catalysis. It is of great importance for understanding the binding mechanism of GH5 cellulases, and provides an effective strategy to improve the catalytic performance of cellulases.
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Affiliation(s)
- Fei Zheng
- Key Laboratory for Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, No. 12 South Zhongguancun Street, Haidian, Beijing, 100081 People’s Republic of China
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing, 100083 People’s Republic of China
| | - Tao Tu
- Key Laboratory for Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, No. 12 South Zhongguancun Street, Haidian, Beijing, 100081 People’s Republic of China
| | - Xiaoyu Wang
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing, 100083 People’s Republic of China
| | - Yuan Wang
- Key Laboratory for Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, No. 12 South Zhongguancun Street, Haidian, Beijing, 100081 People’s Republic of China
| | - Rui Ma
- Key Laboratory for Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, No. 12 South Zhongguancun Street, Haidian, Beijing, 100081 People’s Republic of China
| | - Xiaoyun Su
- Key Laboratory for Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, No. 12 South Zhongguancun Street, Haidian, Beijing, 100081 People’s Republic of China
| | - Xiangming Xie
- College of Biological Sciences and Biotechnology, Beijing Forestry University, Beijing, 100083 People’s Republic of China
| | - Bin Yao
- Key Laboratory for Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, No. 12 South Zhongguancun Street, Haidian, Beijing, 100081 People’s Republic of China
| | - Huiying Luo
- Key Laboratory for Feed Biotechnology of the Ministry of Agriculture, Feed Research Institute, Chinese Academy of Agricultural Sciences, No. 12 South Zhongguancun Street, Haidian, Beijing, 100081 People’s Republic of China
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Alvarez TM, Paiva JH, Ruiz DM, Cairo JPLF, Pereira IO, Paixão DAA, de Almeida RF, Tonoli CCC, Ruller R, Santos CR, Squina FM, Murakami MT. Structure and function of a novel cellulase 5 from sugarcane soil metagenome. PLoS One 2013; 8:e83635. [PMID: 24358302 PMCID: PMC3866126 DOI: 10.1371/journal.pone.0083635] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2013] [Accepted: 11/04/2013] [Indexed: 11/26/2022] Open
Abstract
Cellulases play a key role in enzymatic routes for degradation of plant cell-wall polysaccharides into simple and economically-relevant sugars. However, their low performance on complex substrates and reduced stability under industrial conditions remain the main obstacle for the large-scale production of cellulose-derived products and biofuels. Thus, in this study a novel cellulase with unusual catalytic properties from sugarcane soil metagenome (CelE1) was isolated and characterized. The polypeptide deduced from the celE1 gene encodes a unique glycoside hydrolase domain belonging to GH5 family. The recombinant enzyme was active on both carboxymethyl cellulose and β-glucan with an endo-acting mode according to capillary electrophoretic analysis of cleavage products. CelE1 showed optimum hydrolytic activity at pH 7.0 and 50 °C with remarkable activity at alkaline conditions that is attractive for industrial applications in which conventional acidic cellulases are not suitable. Moreover, its three-dimensional structure was determined at 1.8 Å resolution that allowed the identification of an insertion of eight residues in the β8-α8 loop of the catalytic domain of CelE1, which is not conserved in its psychrophilic orthologs. This 8-residue-long segment is a prominent and distinguishing feature of thermotolerant cellulases 5 suggesting that it might be involved with thermal stability. Based on its unconventional characteristics, CelE1 could be potentially employed in biotechnological processes that require thermotolerant and alkaline cellulases.
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Affiliation(s)
- Thabata M Alvarez
- Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo, Brazil
| | - Joice H Paiva
- Laboratório Nacional de Biociências (LNBio), Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo, Brazil
| | - Diego M Ruiz
- Laboratório Nacional de Biociências (LNBio), Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo, Brazil
| | - João Paulo L F Cairo
- Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo, Brazil
| | - Isabela O Pereira
- Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo, Brazil
| | - Douglas A A Paixão
- Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo, Brazil
| | - Rodrigo F de Almeida
- Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo, Brazil
| | - Celisa C C Tonoli
- Laboratório Nacional de Biociências (LNBio), Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo, Brazil
| | - Roberto Ruller
- Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo, Brazil
| | - Camila R Santos
- Laboratório Nacional de Biociências (LNBio), Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo, Brazil
| | - Fabio M Squina
- Laboratório Nacional de Ciência e Tecnologia do Bioetanol (CTBE), Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo, Brazil
| | - Mario T Murakami
- Laboratório Nacional de Biociências (LNBio), Centro Nacional de Pesquisa em Energia e Materiais, Campinas, São Paulo, Brazil
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Shirey C, Badieyan S, Sobrado P. Role of Ser-257 in the sliding mechanism of NADP(H) in the reaction catalyzed by the Aspergillus fumigatus flavin-dependent ornithine N5-monooxygenase SidA. J Biol Chem 2013; 288:32440-32448. [PMID: 24072704 DOI: 10.1074/jbc.m113.487181] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
SidA (siderophore A) is a flavin-dependent N-hydroxylating monooxygenase that is essential for virulence in Aspergillus fumigatus. SidA catalyzes the NADPH- and oxygen-dependent formation of N(5)-hydroxyornithine. In this reaction, NADPH reduces the flavin, and the resulting NADP(+) is the last product to be released. The presence of NADP(+) is essential for activity, as it is required for stabilization of the C4a-hydroperoxyflavin, which is the hydroxylating species. As part of our efforts to determine the molecular details of the role of NADP(H) in catalysis, we targeted Ser-257 for site-directed mutagenesis and performed extensive characterization of the S257A enzyme. Using a combination of steady-state and stopped-flow kinetic experiments, substrate analogs, and primary kinetic isotope effects, we show that the interaction between Ser-257 and NADP(H) is essential for stabilization of the C4a-hydroperoxyflavin. Molecular dynamics simulation results suggest that Ser-257 functions as a pivot point, allowing the nicotinamide of NADP(+) to slide into position for stabilization of the C4a-hydroperoxyflavin.
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Affiliation(s)
| | | | - Pablo Sobrado
- From the Department of Biochemistry; the Virginia Tech Center for Drug Discovery, Virginia Tech, Blacksburg, Virginia 24061.
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Tryptophan-47 in the active site of Methylophaga sp. strain SK1 flavin-monooxygenase is important for hydride transfer. Arch Biochem Biophys 2013; 532:46-53. [PMID: 23357278 DOI: 10.1016/j.abb.2013.01.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Revised: 12/31/2012] [Accepted: 01/13/2013] [Indexed: 11/21/2022]
Abstract
Flavin-dependent monooxygenase (FMO) from Methylophaga sp. strain SK1 catalyzes the NADPH- and oxygen-dependent hydroxylation of a number of xenobiotics. Reduction of the flavin cofactor by NADPH is required for activation of molecular oxygen. The role of a conserved tryptophan at position 47 was probed by site-directed mutagenesis. FMOW47A resulted in an insoluble inactive protein; in contrast, FMOW47F was soluble and active. The spectrum of the flavin in the mutant enzyme was redshifted, indicating a change in the flavin environment. The kcat values for NADPH, trimethylamine, and methimazole, decreased 5-8-fold. Primary kinetic isotope effect values were higher, indicating that hydride transfer is more rate-limiting in the mutant enzyme. This is supported by a decrease in the rate constant for flavin reduction and in the solvent kinetic isotope effect values. Results from molecular dynamics simulations show reduced flexibility in active site residues and, in particular, the nicotinamide moiety of NADP+ in FMOW47F. This was supported by thermal denaturation experiments. Together, the data suggests that W47 plays a role in maintaining the overall protein flexibility that is required for conformational changes important in hydride transfer.
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