Download MendeleyCrystal Structure of Thermobifida Fusca Endoglucanase Cel6A in Complex with Substrate and Inhibitor: The Role of Tyrosine Y73 in Substrate Ring Distortion.
Larsson, A.M., Bergfors, T., Dultz, E., Irwin, D.C., Roos, A., Driguez, H., Wilson, D.B., Jones, T.A.(2005) Biochemistry 44: 12915
- PubMed: 16185060
- DOI: https://doi.org/10.1021/bi0506730
- Primary Citation of Related Structures:
2BOD, 2BOE, 2BOF, 2BOG - PubMed Abstract:
Endoglucanase Cel6A from Thermobifida fusca hydrolyzes the beta-1,4 linkages in cellulose at accessible points along the polymer. The structure of the catalytic domain of Cel6A from T. fusca in complex with a nonhydrolysable substrate analogue that acts as an inhibitor, methylcellobiosyl-4-thio-beta-cellobioside (Glc(2)-S-Glc(2)), has been determined to 1.5 A resolution. The glycosyl unit in subsite -1 was sterically hindered by Tyr73 and forced into a distorted (2)S(o) conformation. In the enzyme where Tyr73 was mutated to a serine residue, the hindrance was removed and the glycosyl unit in subsite -1 had a relaxed (4)C(1) chair conformation. The relaxed conformation was seen in two complex structures of the mutated enzyme, with cellotetrose (Glc(4)) at 1.64 A and Glc(2)-S-Glc(2) at 1.04 A resolution.
Organizational Affiliation:
Department of Cell and Molecular Biology, University of Uppsala, Biomedical Centre, Box 596, SE-751 24 Uppsala, Sweden.
