PDBsum entry: 1oc5

Hydrolase

PDB id: 1oc5

Contents

Protein chain

364 a.a. *

Ligands

NAG

GOL ×6

MGL-SGC-BGC-BGC

Waters ×471

* Residue conservation analysis

PDB id:

1oc5

Name:

Hydrolase

Title:

D405n mutant of the cellobiohydrolase cel6a from humicola insolens in complex with methyl-cellobiosyl-4-deoxy-4-thio-beta-d-cellobioside

Structure:

Cellobiohydrolase ii. Chain: a. Fragment: catalytic core domain residues 87-450. Synonym: cellulase, cel6a. Engineered: yes. Mutation: yes. Other_details: n-linked n-acetylglucosamine on residue asn 141

Source:

Humicola insolens. Organism_taxid: 34413. Expressed in: aspergillus oryzae. Expression_system_taxid: 5062. Amylase promoter and amyloglucosidase terminator

Resolution:

1.7Å R-factor: 0.129 R-free: 0.168

Authors:

A.Varrot,T.P.Frandsen,I.Von Ossowski,V.Boyer,H.Driguez, M.Schulein,G.J.Davies

Key ref:

A.Varrot et al. (2003). Structural basis for ligand binding and processivity in cellobiohydrolase Cel6A from Humicola insolens. Structure, 11, 855-864. PubMed id: 12842048 DOI: 10.1016/S0969-2126(03)00124-2

Date:

06-Feb-03 Release date: 10-Jul-03

Protein chain

Q9C1S9  (GUX6_HUMIN) -  Exoglucanase-6A

Seq: 476 a.a.

Struc: 364 a.a.*

* PDB and UniProt seqs differ at 12 residue positions (black crosses)

Enzyme reactions

• Enzyme class: E.C.3.2.1.91 - Cellulose 1,4-beta-cellobiosidase (non-reducing end).
• Reaction: Hydrolysis of 1,4-beta-D-glucosidic linkages in cellulose and cellotetraose, releasing cellobiose from the non-reducing ends of the chains.

 Gene Ontology (GO) functional annotation 

• Biological process: carbohydrate metabolic process (2 terms)
• Biochemical function: hydrolase activity, hydrolyzing O-glycosyl compounds (1 term)

DOI no: 10.1016/S0969-2126(03)00124-2

Structure 11:855-864 (2003)

PubMed id: 12842048

Structural basis for ligand binding and processivity in cellobiohydrolase Cel6A from Humicola insolens.

A.Varrot, T.P.Frandsen, I.von Ossowski, V.Boyer, S.Cottaz, H.Driguez, M.Schülein, G.J.Davies.

ABSTRACT

The enzymatic digestion of cellulose entails intimate involvement of cellobiohydrolases, whose characteristic active-center tunnel contributes to a processive degradation of the polysaccharide. The cellobiohydrolase Cel6A displays an active site within a tunnel formed by two extended loops, which are known to open and close in response to ligand binding. Here we present five structures of wild-type and mutant forms of Cel6A from Humicola insolens in complex with nonhydrolyzable thio-oligosaccharides, at resolutions from 1.7-1.1 A, dissecting the structural accommodation of a processing substrate chain through the active center during hydrolysis. Movement of ligand is facilitated by extensive solvent-mediated interactions and through flexibility in the hydrophobic surfaces provided by a sheath of tryptophan residues.

Selected figure(s)

Figure 1.
Figure 1. The Structure of a Single Cellulose ChainWhile b-1,4-linked glucose is the chemical repeating unit, the structural repeat is cellobiose, and, consequently, each glucoside is orientated at 180° with respect to its neighbors, especially in crystalline forms (Gessler et al., 1994).

The above figure is reprinted by permission from Cell Press: Structure (2003, 11, 855-864) copyright 2003.

Figure was selected by an automated process.