Enhanced acidic resistance ability and catalytic properties of Bacillus 1,3-1,4-β-glucanases by sequence alignment and surface charge engineering

• Published in: International journal of biological macromolecules Vol. 192; pp. 426 - 434
• Main Authors: Li, Zhengxue, Niu, Chengtuo, Yang, Xiaohong, Zheng, Feiyun, Liu, Chunfeng, Wang, Jinjing, Li, Qi
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 01.12.2021
• Subjects: Acidic resistance; Amino Acid Sequence; Bacillus - enzymology; Bacillus - genetics; Catalysis; Enzyme Activation; Enzyme Stability; Glycoside Hydrolases - chemistry; Glycoside Hydrolases - genetics; Hydrogen-Ion Concentration; Kinetics; Models, Molecular; Point Mutation; Protein Conformation; Sequence Alignment; Spectrum Analysis; Static Electricity; Structure-Activity Relationship; Surface charge engineering; Temperature; β-Glucanase; Surface charge engineering; β-Glucanase; Acidic resistance
• ISSN: 0141-8130; 1879-0003
• DOI: 10.1016/j.ijbiomac.2021.10.008

High stability at acidic environment is required for 1,3-1,4-β-glucanase to function in biofuel, brewing and animal feed industries. In this study, a mesophilic β-glucanase from Bacillus terquilensis CGX 5-1 was rationally engineered through sequence alignment and surface charge engineering to improve its acidic resistance ability. Nineteen singly-site variants were constructed and Q1E, I133L and V134A variants showed better acidic stability without the compromise of catalytic property and thermostability. Furthermore, four multi-site variants were constructed and one double-site variant Q1E/I133L with better stability at acidic environment and higher catalytic property was obtained. The fluorescence spectroscopy and structural analysis showed that more surface negative charge, decreased exposure degree of residue No.1, shifted side chain direction of residue No.133 and the lower total and folding free energy might be the reason for the improvement of acidic stability of Q1E/I133L variant. The obtained Q1E/I133L variant has potential applications in industries. •An effective method was adopted to engineer β-glucanase towards better acidic tolerance.•Q1E/I133L variant had better acidic resistance ability than that of wild-type.•Q1E/I133L variant showed favorable catalytic efficiency.•The structural stability of Q1E/I133L variant was improved after mutation.•More surface negative charge and lower folding free energy were critical.