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Guo J, Gao W, Wang J, Yao Y, Man Z, Cai Z, Qing Q. Thr22 plays an important role in the efficient catalytic process of Bacillus subtilis chitosanase BsCsn46A. Enzyme Microb Technol 2023; 167:110242. [PMID: 37099965 DOI: 10.1016/j.enzmictec.2023.110242] [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: 02/02/2023] [Revised: 04/11/2023] [Accepted: 04/12/2023] [Indexed: 04/28/2023]
Abstract
Threonine 22 (Thr22) located in catalytic center near the catalytic amino acid Glu19 was non-conserved in Bacillus species chitosanase. In order to study the function of Thr22, saturation mutagenesis was carried out towards P121N, a mutant previously constructed in our laboratory. Compared with P121N, which was designated as the wild type (WT) in this research, the specific enzyme activity of all mutants was decreased, and that of the T22P mutant was decreased by 91.6 %. Among these mutants, the optimum temperature decreased from 55 °C to 50 °C for 10 mutants and 45 °C for 4 mutants, respectively. The optimum temperature of mutant T22P was 40 °C. In order to analyze the reasons for the changes in enzymatic properties of the mutants, molecular docking analysis of WT and its mutants with substrate were performed. The hydrogen bond analysis around position 22 also conducted. The substitution of Thr22 was found to significantly affect the enzyme-substrate complex interaction. In addition, the hydrogen network near position 22 has undergone obvious changes. These changes may be the main reasons for the changes in enzymatic properties of the mutants. Altogether, this study is valuable for the future research on Bacillus chitosanase.
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Affiliation(s)
- Jing Guo
- Laboratory of Applied Microbiology, School of Biological and Food Engineering, Changzhou University, China; Advanced Catalysis and Green Manufacturing Collaborative Innovation Center, Changzhou University, China
| | - Wenjun Gao
- Laboratory of Applied Microbiology, School of Biological and Food Engineering, Changzhou University, China
| | - Jing Wang
- Laboratory of Applied Microbiology, School of Biological and Food Engineering, Changzhou University, China
| | - Yao Yao
- Laboratory of Applied Microbiology, School of Biological and Food Engineering, Changzhou University, China
| | - Zaiwei Man
- Laboratory of Applied Microbiology, School of Biological and Food Engineering, Changzhou University, China; Zao zhuang Key Laboraory of Corn Bioengineering, Zaozhuang Science and Technology Collaborative Innovation Center of Enzyme, Shandong Hengren Gongmao Co. Ltd, Zaozhuang, China.
| | - Zhiqiang Cai
- Laboratory of Applied Microbiology, School of Biological and Food Engineering, Changzhou University, China; Advanced Catalysis and Green Manufacturing Collaborative Innovation Center, Changzhou University, China
| | - Qing Qing
- Laboratory of Applied Microbiology, School of Biological and Food Engineering, Changzhou University, China; Advanced Catalysis and Green Manufacturing Collaborative Innovation Center, Changzhou University, China
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Guo J, Wang Y, Gao W, Wang X, Gao X, Man Z, Cai Z, Qing Q. Gene Cloning, Functional Expression, and Characterization of a Novel GH46 Chitosanase from Streptomyces avermitilis (SaCsn46A). Appl Biochem Biotechnol 2022; 194:813-826. [PMID: 34542822 DOI: 10.1007/s12010-021-03687-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2021] [Accepted: 09/08/2021] [Indexed: 01/20/2023]
Abstract
A n ovel glycoside hydrolase (GH) family 46 chitosanase (SaCsn46A) from Streptomyces avermitilis was cloned and functionally expressed in Escherichia coli Rosetta (DE3) strains. SaCsn46A consists of 271 amino acids, which includes a 34-amino acid signal peptide. The protein sequence of SaCsn46A shows maximum identity (83.5%) to chitosanase from Streptomyces sp. SirexAA-E. Then, the mature enzyme was purified to homogeneity through Ni-chelating affinity chromatography with a recovery yield of 78% and the molecular mass of purified enzyme was estimated to be 29 kDa by SDS-PAGE. The recombinant enzyme possessed a temperature optimum of 45 °C and a pH optimum of 6.2, and it was stable at pH ranging from 4.0 to 9.0 and below 30 °C. The Km and Vmax values of this enzyme were 1.32 mg/mL, 526.32 U/mg/min, respectively (chitosan as substrate). The enzyme activity can be enhanced by Mg2+ and especially Mn2+, which could enhance the activity about 3.62-fold at a 3-mM concentration. The enzyme can hydrolyze a variety of polysaccharides which are linked by β-1,4-glycosidic bonds such as chitin, xylan, and cellulose, but it could not hydrolyze polysaccharides linked by α-1,4-glycosidic bonds. The results of thin-layer chromatography and HPLC showed that the enzyme exhibited an endo-type cleavage pattern and could hydrolyze chitosan to glucosamine (GlcN) and (GlcN)2. This study demonstrated that SaCsn46A is a promising enzyme to produce glucosamine and chitooligosaccharides (COS) from chitosan.
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Affiliation(s)
- Jing Guo
- Advanced Catalysis and Green Manufacturing Collaborative Innovation Center, Changzhou University, Changzhou, China.
- Laboratory of Applied Microbiology, School of Pharmaceutical, Changzhou University, Changzhou, China.
| | - Yi Wang
- Laboratory of Applied Microbiology, School of Pharmaceutical, Changzhou University, Changzhou, China
| | - Wenjun Gao
- Laboratory of Applied Microbiology, School of Pharmaceutical, Changzhou University, Changzhou, China
| | - Xinrou Wang
- Laboratory of Applied Microbiology, School of Pharmaceutical, Changzhou University, Changzhou, China
| | - Xin Gao
- Laboratory of Applied Microbiology, School of Pharmaceutical, Changzhou University, Changzhou, China
| | - Zaiwei Man
- Advanced Catalysis and Green Manufacturing Collaborative Innovation Center, Changzhou University, Changzhou, China.
- School of Petrochemical Engineering, School of Food Science and Technology, Changzhou University, Changzhou, China.
- Zaozhuang Key Laboratory of Corn Bioengineering, Zaozhuang Science and Technology Collaborative Innovation Center of Enzyme, Shandong Hengren Gongmao Co. Ltd, Zaozhuang, China.
| | - Zhiqiang Cai
- Advanced Catalysis and Green Manufacturing Collaborative Innovation Center, Changzhou University, Changzhou, China.
- Laboratory of Applied Microbiology, School of Pharmaceutical, Changzhou University, Changzhou, China.
| | - Qing Qing
- Laboratory of Applied Microbiology, School of Pharmaceutical, Changzhou University, Changzhou, China.
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Guo J, Wang Y, Zhang X, Gao W, Cai Z, Hong T, Man Z, Qing Q. Improvement of the Catalytic Activity of Chitosanase BsCsn46A from Bacillus subtilis by Site-Saturation Mutagenesis of Proline121. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2021; 69:11835-11846. [PMID: 34590486 DOI: 10.1021/acs.jafc.1c04206] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
BsCsn46A, a GH46 family chitosanase from Bacillus subtilis, has great potential for industrial chitooligosaccharide production due to its high activity and stability. In this study, a special amino acid Pro121 was identified not fit in the helix structure, which was located in the opposite side of the active center in BsCsn46A, by the PoPMuSiC algorithm. Then, saturation mutagenesis was performed to explore the role of the site amino acid 121. Compared with the wild type, the specific activity of P121N, P121C, and P121V was increased by 1.69-, 1.97-, and 2.15-fold, respectively. In particular, the specific activity of P121N was increased without loss of thermostability, indicating that replacing the structural stiffness of proline in the helical structure could significantly improve the chitosanase activity. The Km values of P121N, P121C, and P121V decreased significantly, indicating that the affinity between the enzyme-substrate complex was enhanced. Through molecular docking, it was found that the increase of hydrogen bonds and van der Waals force between the enzyme-substrate complex and the removal of unfavorable bonds might be the main reason for the change of enzyme properties. In addition, the optimal temperature of the three mutants changed from 60 to 55 °C. These results indicate that the site 121 plays a critical role in the catalytic activity and enzymatic properties of chitosanase. To our knowledge, the results provide novel data on chitosanase activity and identify an excellent candidate of industrial chitosanase.
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Affiliation(s)
- Jing Guo
- Advanced Catalysis and Green Manufacturing Collaborative Innovation Center, Changzhou University, Changzhou, Jiangsu 213164, China
- Laboratory of Applied Microbiology, School of Pharmaceutical, Changzhou University, Changzhou 213164, Jiangsu, China
| | - Yi Wang
- Laboratory of Applied Microbiology, School of Pharmaceutical, Changzhou University, Changzhou 213164, Jiangsu, China
| | - Xuan Zhang
- Laboratory of Applied Microbiology, School of Pharmaceutical, Changzhou University, Changzhou 213164, Jiangsu, China
| | - Wenjun Gao
- Laboratory of Applied Microbiology, School of Pharmaceutical, Changzhou University, Changzhou 213164, Jiangsu, China
| | - Zhiqiang Cai
- Advanced Catalysis and Green Manufacturing Collaborative Innovation Center, Changzhou University, Changzhou, Jiangsu 213164, China
- Laboratory of Applied Microbiology, School of Pharmaceutical, Changzhou University, Changzhou 213164, Jiangsu, China
| | - Tingting Hong
- Advanced Catalysis and Green Manufacturing Collaborative Innovation Center, Changzhou University, Changzhou, Jiangsu 213164, China
- Laboratory of Applied Microbiology, School of Pharmaceutical, Changzhou University, Changzhou 213164, Jiangsu, China
| | - Zaiwei Man
- Advanced Catalysis and Green Manufacturing Collaborative Innovation Center, Changzhou University, Changzhou, Jiangsu 213164, China
- School of Petrochemical Engineering, School of food Science and Technology, Changzhou University, Changzhou, Jiangsu 213164, China
- Zaozhuang Key Laboratory of Corn Bioengineering, Zaozhuang Science and Technology Collaborative Innovation Center of Enzyme, Shandong Hengren Gongmao Co. Ltd, Zaozhuang 277100, China
| | - Qing Qing
- Advanced Catalysis and Green Manufacturing Collaborative Innovation Center, Changzhou University, Changzhou, Jiangsu 213164, China
- Laboratory of Applied Microbiology, School of Pharmaceutical, Changzhou University, Changzhou 213164, Jiangsu, China
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Zhou Z, Wang X. Improve thermostability of Bacillus sp. TS chitosanase through structure-based alignment. Sci Rep 2021; 11:15846. [PMID: 34349190 PMCID: PMC8339078 DOI: 10.1038/s41598-021-95369-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Accepted: 07/26/2021] [Indexed: 11/22/2022] Open
Abstract
Chitosanases can catalyze the release of chitooligosaccharides which have a number of medical applications. Therefore, Chitosanases are good candidates for large-scale enzymatic synthesis due to their favorable thermostability properties and high catalytic efficiency. To further improve the thermostability of a chitosanase from Bacillus sp. TS, which has a half-life of 5.32 min, we mutated specific serine residues that we identified as potentially relevant through structure comparison with thermophilic CelA from Clostridium thermocellum. Out of a total of 15 mutants, three, namely S265G, S276A, and S347G, show higher thermostability. Their half-lives at 60 °C were calculated as 34.57 min, 36.79 min and 7.2 min. The Km values of S265G, S276A and S347G mutants show substrate binding ability comparable to that of the wild-type enzyme, while the S265G mutant displays a significant decrease of enzymatic activities. Additionally, we studied the synergistic effects of combined mutations, observing that all double mutants and the triple mutant are more stable than the wild-type enzyme and single mutants. Finally, we investigated the mechanisms which might give a reasonable explanation for the improved thermostability via comparative analysis of the resulting 3D structures.
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Affiliation(s)
- Zhanping Zhou
- Tianjin Sinonocy Biological Technology Co. Ltd., Tianjin, 300308, China
| | - Xiao Wang
- Nanfang College of Sun Yat-Sen University, Guangzhou, 510970, China.
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