@article{
author = "Prates, Érica T. and Stanković, Ivana and Silveira, Rodrigo L. and Liberato, Marcelo V. and Henrique-Silva, Flávio and Pereira, Nei Jr. and Polikarpov, Igor and Skaf, Munir S.",
year = "2013",
abstract = "Plant biomass holds a promise for the production of second-generation ethanol via enzymatic hydrolysis, but its utilization as a biofuel resource is currently limited to a large extent by the cost and low efficiency of the cellulolytic enzymes.
Considerable efforts have been dedicated to elucidate the mechanisms of the enzymatic process. It is well known that most cellulases possess a catalytic core domain and a carbohydrate binding module (CBM), without which the enzymatic activity
can be drastically reduced. However, Cel12A members of the glycosyl hydrolases family 12 (GHF12) do not bear a CBM and
yet are able to hydrolyze amorphous cellulose quite efficiently. Here, we use X-ray crystallography and molecular dynamics
simulations to unravel the molecular basis underlying the catalytic capability of endoglucanase 3 from Trichoderma
harzianum (ThEG3), a member of the GHF12 enzymes that lacks a CBM. A comparative analysis with the Cellulomonas fimi
CBM identifies important residues mediating interactions of EG3s with amorphous regions of the cellulose. For instance,
three aromatic residues constitute a harboring wall of hydrophobic contacts with the substrate in both ThEG3 and CfCBM
structures. Moreover, residues at the entrance of the active site cleft of ThEG3 are identified, which might hydrogen bond to
the substrate. We advocate that the ThEG3 residues Asn152 and Glu201 interact with the substrate similarly to the
corresponding CfCBM residues Asn81 and Arg75. Altogether, these results show that CBM motifs are incorporated within
the ThEG3 catalytic domain and suggest that the enzymatic efficiency is associated with the length and position of the
substrate chain, being higher when the substrate interact with the aromatic residues at the entrance of the cleft and the
catalytic triad. Our results provide guidelines for rational protein engineering aiming to improve interactions of GHF12
enzymes with cellulosic substrates.",
publisher = "Public Library of Science",
journal = "PLOS ONE",
title = "X-ray Structure and Molecular Dynamics Simulations of Endoglucanase 3 from Trichoderma harzianum: Structural Organization and Substrate Recognition by Endoglucanases That Lack Cellulose Binding Module",
volume = "8",
number = "3",
pages = "e59069",
doi = "10.1371/journal.pone.0059069"
}
