PDBsum entry 1g0c

Hydrolase

PDB id: 1g0c

Contents

Protein chain

358 a.a. *

Ligands

BGC-BGC

ACY ×4

Metals

_CD ×10

Waters ×474

* Residue conservation analysis

PDB id:

1g0c

Name:

Hydrolase

Title:

Alkaline cellulase k catalytic domain-cellobiose complex

Structure:

Endoglucanase. Chain: a. Fragment: alkaline cellulase k catalytic domain. Engineered: yes

Source:

Bacillus sp.. Organism_taxid: 1415. Strain: ksm-635. Expressed in: bacillus subtilis. Expression_system_taxid: 1423.

Resolution:

1.90Å R-factor: 0.181 R-free: 0.204

Authors:

T.Shirai,H.Ishida,J.Noda,T.Yamane,K.Ozaki,Y.Hakamada,S.Ito

Key ref:

T.Shirai et al. (2001). Crystal structure of alkaline cellulase K: insight into the alkaline adaptation of an industrial enzyme. J Mol Biol, 310, 1079-1087. PubMed id: 11501997 DOI: 10.1006/jmbi.2001.4835

Date:

05-Oct-00 Release date: 01-Aug-01

Protein chain

P19424  (GUN_BACS6) -  Endoglucanase from Bacillus sp. (strain KSM-635)

Seq: 941 a.a.

Struc: 358 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.

DOI no: 10.1006/jmbi.2001.4835

J Mol Biol 310:1079-1087 (2001)

PubMed id: 11501997

Crystal structure of alkaline cellulase K: insight into the alkaline adaptation of an industrial enzyme.

T.Shirai, H.Ishida, J.Noda, T.Yamane, K.Ozaki, Y.Hakamada, S.Ito.

ABSTRACT

The crystal structure of the catalytic domain of alkaline cellulase K was determined at 1.9 A resolution. Because of the most alkaliphilic nature and it's highest activity at pH 9.5, it is used commercially in laundry detergents. An analysis of the structural bases of the alkaliphilic character of the enzyme suggested a mechanism similar to that previously proposed for alkaline proteases, that is, an increase in the number of Arg, His, and Gln residues, and a decrease in Asp and Lys residues. Some ion pairs were formed by the gained Arg residues, which is similar to what has been found in the alkaline proteases. Lys-Asp ion pairs are disfavored and partly replaced with Arg-Asp ion pairs. The alkaline adaptation appeared to be a remodeling of ion pairs so that the charge balance is kept in the high pH range.

Selected figure(s)

Figure 2.
Figure 2. (a) The active center structure of the CelK-cellobiose complex. Side-chains of the active site residues are shown in orange. The red sphere is the cadmium ion found at the catalytic site. Hydrogen bonds are shown in yellow. The cellobiose molecule is shown in green. F[o] -F[c] electron density map is superimposed to the model (contoured at 2.5s level, the atoms of cellobiose were excluded from the phase calculation). (b) The active center and carbohydrate ligand structures of CelK and Cel5A in different ligand states. Only the main-chain atoms are presented for the loops Ala233-Gly239 of Cel5A and Gln490-Gly495 of CelK. The bound sugars are labeled according to the binding sites. Hydrogen bonds are shown in yellow. The superimposed structures are Cel5A without ligand (open conformation, green), complexed with cellobiose (open conformation, blue) and covalent-intermediate (closed conformation, gray) and CelK without ligand (closed conformation, red) and cellobiose complex (closed conformation, orange).

Figure 5.
Figure 5. Spatial distribution of the acquired Arg and His residues (red) and eliminated Lys residues (gray) that appeared to be responsible for the ion pair remodeling. Shown in blue are the negatively charged residues that might form an ion pair with the Arg, His or Lys residues. The cellobiose molecule is shown in green. Hydrogen bonds are shown in yellow.

The above figures are reprinted by permission from Elsevier: J Mol Biol (2001, 310, 1079-1087) copyright 2001.

Figures were selected by an automated process.