3AZT

Diverse Substrates Recognition Mechanism Revealed by Thermotoga maritima Cel5A Structures in Complex with Cellotetraose

Summary for 3AZT

• Entry DOI: 10.2210/pdb3azt/pdb
• Related: 3AMC 3AMD 3AMG 3AOF 3AZR 3AZS
• Descriptor: Endoglucanase, beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-beta-D-glucopyranose-(1-4)-alpha-D-glucopyranose (3 entities in total)
• Functional Keywords: cellulose, cellulase, biofuel, tim barrel, hydrolase
• Biological source: Thermotoga maritima
• Total number of polymer chains: 4
• Total formula weight: 150855.11

Authors

Wu, T.H.,Huang, C.H.,Ko, T.P.,Lai, H.L.,Ma, Y.,Chen, C.C.,Cheng, Y.S.,Liu, J.R.,Guo, R.T. (deposition date: 2011-05-30, release date: 2011-08-10, Last modification date: 2023-11-01)

Primary citation

Wu, T.H.,Huang, C.H.,Ko, T.P.,Lai, H.L.,Ma, Y.,Chen, C.C.,Cheng, Y.S.,Liu, J.R.,Guo, R.T.
Diverse substrate recognition mechanism revealed by Thermotoga maritima Cel5A structures in complex with cellotetraose, cellobiose and mannotriose
Biochim.Biophys.Acta, 1814:1832-1840, 2011

PubMed Abstract: The hyperthermophilic endoglucanase Cel5A from Thermotoga maritima can find applications in lignocellulosic biofuel production, because it catalyzes the hydrolysis of glucan- and mannan-based polysaccharides. Here, we report the crystal structures in apo-form and in complex with three ligands, cellotetraose, cellobiose and mannotriose, at 1.29Å to 2.40Å resolution. The open carbohydrate-binding cavity which can accommodate oligosaccharide substrates with extensively branched chains explained the dual specificity of the enzyme. Combining our structural information and the previous kinetic data, it is suggested that this enzyme prefers β-glucosyl and β-mannosyl moieties at the reducing end and uses two conserved catalytic residues, E253 (nucleophile) and E136 (general acid/base), to hydrolyze the glycosidic bonds. Moreover, our results also suggest that the wide spectrum of Tm_Cel5A substrates might be due to the lack of steric hindrance around the C2-hydroxyl group of the glucose or mannose unit from active-site residues.

PubMed: 21839861
DOI: 10.1016/j.bbapap.2011.07.020

Experimental method

X-RAY DIFFRACTION (1.8 Å)