Download MendeleyCharacterization and crystal structure of a thermostable glycoside hydrolase family 45 1,4-beta-endoglucanase from Thielavia terrestris
Gao, J., Huang, J.W., Li, Q., Liu, W.D., Ko, T.P., Zheng, Y.Y., Xiao, X., Kuo, C.J., Chen, C.C., Guo, R.T.(2017) Enzyme Microb Technol 99: 32-37
- PubMed: 28193329
- DOI: https://doi.org/10.1016/j.enzmictec.2017.01.005
- Primary Citation of Related Structures:
5GLX, 5GLY, 5GM9 - PubMed Abstract:
1,4-β-Endoglucanase is one of the most important biocatalysts in modern industries. Here, a glycoside hydrolase (GH) family 45 endoglucanase from thermophilic fungus Theilavia terrestris (TtCel45A) was expressed in Pichia pastoris. The recombinant protein shows optimal activity at 60°C, pH 4-5. The enzyme exhibits extraordinary thermostability that more than 80% activity was detected after heating at 80°C for 2.5h. The high resolution crystal structures of apo-form enzyme and that in complex with cellobiose and cellotetraose were solved to 1.36-1.58Å. The protein folds into two overall regions: one is a six-stranded β-barrel, and the other one consists of several extended loops. Between the two regions lies the substrate-binding channel, which is an open cleft spanning across the protein surface. A continuous substrate-binding cleft from subsite -4 to +3 were clearly identified in the complex structures. Notably, the flexible V-VI loop ( 113 Gly- 114 Gly- 115 Asp- 116 Leu- 117 Gly- 118 Ser) is found to open in the presence of -1 sugar, with D115 and L116 swung away to yield a space to accommodate the catalytic acid D122 and the 2,5 B boat conformation of -1 sugar during transition state. Collectively, we characterized the enzyme properties of P. pastoris-expressed TtCel45A and solved high-resolution crystal structures of the enzyme. These results are of great interests in industrial applications and provide new insights into the fundamental understanding of enzyme catalytic mechanism of GH45 endoglucanases.
- Industrial Enzymes National Engineering Laboratory, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin, 300308, China.
Organizational Affiliation:
