PDBsum entry: 1lf1

Hydrolase

PDB id: 1lf1

Contents

Protein chain

296 a.a. *

Waters ×81

* Residue conservation analysis

PDB id:

1lf1

Name:

Hydrolase

Title:

Crystal structure of cel5 from alkalophilic bacillus sp.

Structure:

Cel5. Chain: a. Engineered: yes

Source:

Bacillus subtilis. Organism_taxid: 1423. Expressed in: bacillus subtilis. Expression_system_taxid: 1423.

Resolution:

1.70Å R-factor: 0.183 R-free: 0.223

Authors:

A.Shaw,R.Bott,C.Vonrhein,G.Bricogne,S.Power,A.G.Day

Key ref:

A.Shaw et al. (2002). A novel combination of two classic catalytic schemes. J Mol Biol, 320, 303-309. PubMed id: 12079387 DOI: 10.1016/S0022-2836(02)00387-X

Date:

10-Apr-02 Release date: 03-Jul-02

Protein chain

Q59232  (Q59232_BACSP) -  Endo-beta-1,4-glucanase (Precursor)

Seq: 389 a.a.

Struc: 296 a.a.*

* PDB and UniProt seqs differ at 6 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/S0022-2836(02)00387-X

J Mol Biol 320:303-309 (2002)

PubMed id: 12079387

A novel combination of two classic catalytic schemes.

A.Shaw, R.Bott, C.Vonrhein, G.Bricogne, S.Power, A.G.Day.

ABSTRACT

The crystal structure of an alkaline Bacillus cellulase catalytic core, from glucoside hydrolase family 5, reveals a novel combination of the catalytic machinery of two classic textbook enzymes. The enzyme has the expected two glutamate residues in close proximity to one another in the active-site that are typical of retaining cellulases. However, the proton donor, glutamate 139 is also unexpectedly a member of a serine-histidine-glutamate catalytic triad, forming a novel combination of catalytic machineries. Structure and sequence analysis of glucoside hydrolase family 5 reveal that the triad is highly conserved, but with variations at the equivalent of the serine position. We speculate that the purpose of this novel catalytic triad is to control the protonation of the acid/base glutamate, facilitating the first step of the catalytic reaction, protonation of the substrate, by the proton donor glutamate. If correct, this will be a novel use for a catalytic triad.

Selected figure(s)

Figure 1.
Figure 1. The stereoviews of the structure of the catalytic domain of cellulase 103. (a) The electron density map of in the active-site, including the catalytic triad, after heavy-atom refinement and phasing using SHARP, and subsequent density modification using SOLOMON.38 (b) Ribbons diagram of the tertiary structure, with the catalytic triad and the Glu nucleophile.

Figure 2.
Figure 2. A comparison of the catalytic triads found in GH5 enzymes. (a) The type A triad from cellulase 103. (b) The type B triad of exo-1,3-glucanase from Candida albicans.23 (c) The type C triad of 1BQC; Thermobifida fusca b-mannanase.18

The above figures are reprinted by permission from Elsevier: J Mol Biol (2002, 320, 303-309) copyright 2002.