Download MendeleyCrystal Complex Structures Reveal How Substrate is Bound in the -4 to the +2 Binding Sites of Humicola Grisea Cel12A
Sandgren, M., Berglund, G.I., Shaw, A., Stahlberg, J., Kenne, L., Desmet, T., Mitchinson, C.(2004) J Mol Biol 342: 1505
- PubMed: 15364577
- DOI: https://doi.org/10.1016/j.jmb.2004.07.098
- Primary Citation of Related Structures:
1UU4, 1UU5, 1UU6, 1W2U - PubMed Abstract:
As part of an ongoing enzyme discovery program to investigate the properties and catalytic mechanism of glycoside hydrolase family 12 (GH 12) endoglucanases, a GH family that contains several cellulases that are of interest in industrial applications, we have solved four new crystal structures of wild-type Humicola grisea Cel12A in complexes formed by soaking with cellobiose, cellotetraose, cellopentaose, and a thio-linked cellotetraose derivative (G2SG2). These complex structures allow mapping of the non-covalent interactions between the enzyme and the glucosyl chain bound in subsites -4 to +2 of the enzyme, and shed light on the mechanism and function of GH 12 cellulases. The unhydrolysed cellopentaose and the G2SG2 cello-oligomers span the active site of the catalytically active H.grisea Cel12A enzyme, with the pyranoside bound in subsite -1 displaying a S31 skew boat conformation. After soaking in cellotetraose, the cello-oligomer that is found bound in site -4 to -1 contains a beta-1,3-linkage between the two cellobiose units in the oligomer, which is believed to have been formed by a transglycosylation reaction that has occurred during the ligand soak of the protein crystals. The close fit of this ligand and the binding sites occupied suggest a novel mixed beta-glucanase activity for this enzyme.
Organizational Affiliation:
Department of Cell and Molecular Biology, Uppsala University, Biomedical Center, Box 596, SE-751 24 Uppsala, Sweden. mats@xray.bmc.uu.se
