PDBsum entry 4c4c

Hydrolase

PDB id: 4c4c

Contents

Protein chain

434 a.a.

Ligands

BGC-BGC-BGC-BGC-BGC-BGC-BGC-BGC-BGC

NAG ×2

PEG ×3

Metals

_CO ×3

Waters ×675

PDB id:

4c4c

Name:

Hydrolase

Title:

Michaelis complex of hypocrea jecorina cel7a e217q mutant with cellononaose spanning the active site

Structure:

Cellulose 1,4-beta-cellobiosidase. Chain: a. Fragment: catalytic module, residues 18-451. Engineered: yes. Mutation: yes

Source:

Trichoderma reesei. Organism_taxid: 51453. Strain: vtt-d-93201. Variant: qm9414. Expressed in: trichoderma reesei. Expression_system_taxid: 51453.

Resolution:

1.45Å R-factor: 0.171 R-free: 0.196

Authors:

M.Haddad-Momeni,M.Sandgren,J.Stahlberg

Key ref:

B.C.Knott et al. (2014). The mechanism of cellulose hydrolysis by a two-step, retaining cellobiohydrolase elucidated by structural and transition path sampling studies. J Am Chem Soc, 136, 321-329. PubMed id: 24341799 DOI: 10.1021/ja410291u

Date:

05-Sep-13 Release date: 08-Jan-14

Protein chain

P62694  (GUX1_HYPJE) -  Exoglucanase 1 from Hypocrea jecorina

Seq: 513 a.a.

Struc: 434 a.a.*

* PDB and UniProt seqs differ at 3 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.

DOI no: 10.1021/ja410291u

J Am Chem Soc 136:321-329 (2014)

PubMed id: 24341799

The mechanism of cellulose hydrolysis by a two-step, retaining cellobiohydrolase elucidated by structural and transition path sampling studies.

B.C.Knott, M.Haddad Momeni, M.F.Crowley, L.F.Mackenzie, A.W.Götz, M.Sandgren, S.G.Withers, J.Ståhlberg, G.T.Beckham.

ABSTRACT

Glycoside hydrolases (GHs) cleave glycosidic linkages in carbohydrates, typically via inverting or retaining mechanisms, the latter of which proceeds via a two-step mechanism that includes formation of a glycosyl-enzyme intermediate. We present two new structures of the catalytic domain of Hypocrea jecorina GH Family 7 cellobiohydrolase Cel7A, namely a Michaelis complex with a full cellononaose ligand and a glycosyl-enzyme intermediate, that reveal details of the 'static' reaction coordinate. We also employ transition path sampling to determine the 'dynamic' reaction coordinate for the catalytic cycle. The glycosylation reaction coordinate contains components of forming and breaking bonds and a conformational change in the nucleophile. Deglycosylation proceeds via a product-assisted mechanism wherein the glycosylation product, cellobiose, positions a water molecule for nucleophilic attack on the anomeric carbon of the glycosyl-enzyme intermediate. In concert with previous structures, the present results reveal the complete hydrolytic reaction coordinate for this naturally and industrially important enzyme family.