5GLX image
Entry Detail
PDB ID:
5GLX
Keywords:
Title:
Crystal structure of a glycoside hydrolase from Thielavia terrestris NRRL 8126
Biological Source:
PDB Version:
Deposition Date:
2016-07-12
Release Date:
2017-04-19
Method Details:
Experimental Method:
Resolution:
1.42 Å
R-Value Free:
0.16
R-Value Work:
0.13
R-Value Observed:
0.13
Space Group:
P 1 21 1
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:Glycoside hydrolase family 45 protein
Chain IDs:A
Chain Length:217
Number of Molecules:1
Biological Source:Thielavia terrestris NRRL 8126
Primary Citation
Characterization and crystal structure of a thermostable glycoside hydrolase family 45 1,4-beta-endoglucanase from Thielavia terrestris
Enzyme Microb. Technol. 99 32 37 (2017)
PMID: 28193329 DOI: 10.1016/j.enzmictec.2017.01.005

Abstact

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 (113Gly-114Gly-115Asp-116Leu-117Gly-118Ser) 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 2,5B 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.

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