Crystal complex structures reveal how substrate is bound in the -4 to the +2 binding sites of Humicola grisea Cel12A
| Autor: | Jerry Ståhlberg, Tom Desmet, Andrew Shaw, Gunnar I. Berglund, Mats Sandgren, Lennart Kenne, Colin Mitchinson |
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| Rok vydání: | 2004 |
| Předmět: |
Models
Molecular Cellobiose Stereochemistry Protein Conformation Oligosaccharides Crystallography X-Ray Oligomer Catalysis Substrate Specificity chemistry.chemical_compound Structure-Activity Relationship Ascomycota Cellulase Structural Biology Hydrolase Glycoside hydrolase Binding site Cellulose Molecular Biology Binding Sites biology Substrate (chemistry) Active site Ligand (biochemistry) Crystallography chemistry biology.protein Tetroses Protein Binding |
| Zdroj: | Journal of molecular biology. 342(5) |
| ISSN: | 0022-2836 |
| Popis: | 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 S 3 1 skew boat conformation. After soaking in cellotetraose, the cello-oligomer that is found bound in site −4 to −1 contains a β-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 β-glucanase activity for this enzyme. |
| Databáze: | OpenAIRE |
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