PDBsum entry: 1edg

Cellulose degradation

PDB id: 1edg

Contents

Protein chain

380 a.a. *

Waters ×375

* Residue conservation analysis

PDB id:

1edg

Name:

Cellulose degradation

Title:

Single crystal structure determination of the catalytic doma celcca carried out at 15 degreE C

Structure:

Endoglucanase a. Chain: a. Fragment: catalytic domain, c terminus truncated. Synonym: endo-(1,4)-beta-glucanase, celcca. Engineered: yes. Other_details: family 5 of glycosyl hydrolases

Source:

Clostridium cellulolyticum. Organism_taxid: 394503. Strain: h10. Atcc: 35319. Gene: celcca. Expressed in: escherichia coli. Expression_system_taxid: 562.

Resolution:

1.60Å R-factor: 0.191 R-free: 0.220

Authors:

V.Ducros,M.Czjzek,R.Haser

Key ref:

V.Ducros et al. (1995). Crystal structure of the catalytic domain of a bacterial cellulase belonging to family 5. Structure, 3, 939-949. PubMed id: 8535787 DOI: 10.1016/S0969-2126(01)00228-3

Date:

07-Jul-95 Release date: 17-Aug-96

Protein chain

P17901  (GUNA_CLOCE) -  Endoglucanase A

Seq: 475 a.a.

Struc: 380 a.a.*

* PDB and UniProt seqs differ at 5 residue positions (black crosses)

Enzyme reactions

• Enzyme class: E.C.3.2.1.4 - Cellulase.
• Reaction: Endohydrolysis of 1,4-beta-D-glucosidic linkages in cellulose, lichenin and cereal beta-D-glucans.

 Gene Ontology (GO) functional annotation 

• Biological process: carbohydrate metabolic process (1 term)
• Biochemical function: catalytic activity (3 terms)

DOI no: 10.1016/S0969-2126(01)00228-3

Structure 3:939-949 (1995)

PubMed id: 8535787

Crystal structure of the catalytic domain of a bacterial cellulase belonging to family 5.

V.Ducros, M.Czjzek, A.Belaich, C.Gaudin, H.P.Fierobe, J.P.Belaich, G.J.Davies, R.Haser.

ABSTRACT

BACKGROUND: Cellulases are glycosyl hydrolases--enzymes that hydrolyze glycosidic bonds. They have been widely studied using biochemical and microbiological techniques and have attracted industrial interest because of their potential in biomass conversion and in the paper and textile industries. Glycosyl hydrolases have lately been assigned to specific families on the basis of similarities in their amino acid sequences. The cellulase endoglucanase A produced by Clostridium cellulolyticum (CelCCA) belongs to family 5. RESULTS: We have determined the crystal structure of the catalytic domain of CelCCA at a resolution of 2.4 A and refined it to 1.6 A. The structure was solved by the multiple isomorphous replacement method. The overall structural fold, (alpha/beta)8, belongs to the TIM barrel motif superfamily. The catalytic centre is located at the C-terminal ends of the beta strands; the aromatic residues, forming the substrate-binding site, are arranged along a long cleft on the surface of the globular enzyme. CONCLUSIONS: Strictly conserved residues within family 5 are described with respect to their catalytic function. The proton donor, Glu170, and the nucleophile, Glu307, are localized on beta strands IV and VII, respectively, and are separated by 5.5 A, as expected for enzymes which retain the configuration of the substrate's anomeric carbon. Structure determination of the catalytic domain of CelCCA allows a comparison with related enzymes belonging to glycosyl hydrolase families 2, 10 and 17, which also display an (alpha/beta)8 fold.

Selected figure(s)

Figure 2.
Figure 2. The eightfold α/β barrel of the catalytic domain of the endoglucanase A from C. cellulolyticum. (a) Ribbon representation, viewed from the side, of the barrel showing the cleft formed by the loops at the C-terminal extremity of the barrel. β strands are shown as green arrows and the α helices as violet spirals. One additional α helix is located at the N-terminal extremity and this is coloured red. (Figure generated using TURBO-FRODO [50].) (b) Stereo Cα trace of CelCCA viewed along the barrel axis. Figure 2. The eightfold α/β barrel of the catalytic domain of the endoglucanase A from C. cellulolyticum. (a) Ribbon representation, viewed from the side, of the barrel showing the cleft formed by the loops at the C-terminal extremity of the barrel. β strands are shown as green arrows and the α helices as violet spirals. One additional α helix is located at the N-terminal extremity and this is coloured red. (Figure generated using TURBO-FRODO [[4]50].) (b) Stereo Cα trace of CelCCA viewed along the barrel axis.

Figure 5.
Figure 5. Top view of the groove running along the surface of the (α/β)[8] barrel showing the distribution of the aromatic residues (purple), which form the substrate-binding site, on alternate sides of the groove. The two catalytic glutamates are shown in blue. Figure 5. Top view of the groove running along the surface of the (α/β)[8] barrel showing the distribution of the aromatic residues (purple), which form the substrate-binding site, on alternate sides of the groove. The two catalytic glutamates are shown in blue.

The above figures are reprinted by permission from Cell Press: Structure (1995, 3, 939-949) copyright 1995.

Figures were selected by an automated process.