1eg1
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ENDOGLUCANASE I FROM TRICHODERMA REESEI
OverviewOverview
Cellulose is the most abundant polymer in the biosphere. Although, generally resistant to degradation, it may be hydrolysed by cellulolytic, organisms that have evolved a variety of structurally distinct enzymes, cellobiohydrolases and endoglucanases, for this purpose. Endoglucanase I, (EG I) is the major endoglucanase produced by the cellulolytic fungus, Trichoderma reesei, accounting for 5 to 10% of the total amount of, cellulases produced by this organism. Together with EG I from Humicola, insolens and T. reesei cellobiohydrolase I (CBH I), the enzyme is, classified into family 7 of the glycosyl hydrolases, and it catalyses, hydrolysis with a net retention of the anomeric configuration.The, structure of the catalytic core domain (residues 1 to 371) of EG I from T., reesei has been determined at 3.6 A resolution by the molecular, replacement method using the structures of T. reesei CBH I and H. insolens, EG I as search models. By employing the 2-fold non-crystallographic, symmetry (NCS), the structure was refined successfully, despite the, limited resolution. The final model has an R-factor of 0.201 (Rfree, 0.258).The structure of EG I reveals an extended, open substrate-binding, cleft, rather than a tunnel as found in the homologous cellobiohydrolase, CBH I. This confirms the earlier proposal that the tunnel-forming loops in, CBH I have been deleted in EG I, which has resulted in an open active site, in EG I, enabling it to function as an endoglucanase. Comparison of the, structure of EG I with several related enzymes reveals structural, similarities, and differences that relate to their biological function in, degrading particular substrates. A possible structural explanation of the, drastically different pH profiles of T. reesei and H. insolens EG I is, proposed.
About this StructureAbout this Structure
1EG1 is a Single protein structure of sequence from Hypocrea jecorina with NAG as ligand. Active as Cellulase, with EC number 3.2.1.4 Full crystallographic information is available from OCA.
ReferenceReference
The crystal structure of the catalytic core domain of endoglucanase I from Trichoderma reesei at 3.6 A resolution, and a comparison with related enzymes., Kleywegt GJ, Zou JY, Divne C, Davies GJ, Sinning I, Stahlberg J, Reinikainen T, Srisodsuk M, Teeri TT, Jones TA, J Mol Biol. 1997 Sep 26;272(3):383-97. PMID:9325098
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