PDBsum entry: 1m4w

Hydrolase

PDB id: 1m4w

Contents

Protein chain

197 a.a. *

Ligands

NAG-NAG-BMA-MAN

ACT

GOL

Waters ×183

* Residue conservation analysis

PDB id:

1m4w

Name:

Hydrolase

Title:

Thermophilic b-1,4-xylanase from nonomuraea flexuosa

Structure:

Endoxylanase. Chain: a. Engineered: yes

Source:

Thermopolyspora flexuosa. Organism_taxid: 103836. Expressed in: hypocrea jecorina. Expression_system_taxid: 51453

Resolution:

2.10Å R-factor: 0.146 R-free: 0.209

Authors:

N.Hakulinen,O Turunen,J.Janis,M.Leisola,J.Rouvinen

Key ref:

N.Hakulinen et al. (2003). Three-dimensional structures of thermophilic beta-1,4-xylanases from Chaetomium thermophilum and Nonomuraea flexuosa. Comparison of twelve xylanases in relation to their thermal stability. Eur J Biochem, 270, 1399-1412. PubMed id: 12653995 DOI: 10.1046/j.1432-1033.2003.03496.x

Date:

05-Jul-02 Release date: 08-Jul-03

Protein chain

Q8GMV7  (Q8GMV7_9ACTO) -  Endo-1,4-beta-xylanase (Precursor)

Seq: 344 a.a.

Struc: 197 a.a.

Enzyme reactions

• Enzyme class: E.C.3.2.1.8 - Endo-1,4-beta-xylanase.
• Reaction: Endohydrolysis of 1,4-beta-D-xylosidic linkages in xylans.

 Gene Ontology (GO) functional annotation 

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

DOI no: 10.1046/j.1432-1033.2003.03496.x

Eur J Biochem 270:1399-1412 (2003)

PubMed id: 12653995

Three-dimensional structures of thermophilic beta-1,4-xylanases from Chaetomium thermophilum and Nonomuraea flexuosa. Comparison of twelve xylanases in relation to their thermal stability.

N.Hakulinen, O.Turunen, J.Jänis, M.Leisola, J.Rouvinen.

ABSTRACT

The crystal structures of thermophilic xylanases from Chaetomium thermophilum and Nonomuraea flexuosa were determined at 1.75 and 2.1 A resolution, respectively. Both enzymes have the overall fold typical to family 11 xylanases with two highly twisted beta-sheets forming a large cleft. The comparison of 12 crystal structures of family 11 xylanases from both mesophilic and thermophilic organisms showed that the structures of different xylanases are very similar. The sequence identity differences correlated well with the structural differences. Several minor modifications appeared to be responsible for the increased thermal stability of family 11 xylanases: (a) higher Thr : Ser ratio (b) increased number of charged residues, especially Arg, resulting in enhanced polar interactions, and (c) improved stabilization of secondary structures involved the higher number of residues in the beta-strands and stabilization of the alpha-helix region. Some members of family 11 xylanases have a unique strategy to improve their stability, such as a higher number of ion pairs or aromatic residues on protein surface, a more compact structure, a tighter packing, and insertions at some regions resulting in enhanced interactions.

Selected figure(s)

Figure 1.
Fig. 1. CTX. (A) The overall structure of CTX. Glycerol and catalytic glutamates are shown in the active site. (B) A tetrameric assembly with sulfate ions. Molecules A and B are shown in white and symmetry molecules C and D in blue.

Figure 2.
Fig. 2. NFX. (A) The overall structure of NFX with a glycerol molecule in the active site. Carbohydrates attached to Asn7 are shown in gray sticks. (B) The representative 2F[o] –F[c] electron density map from the final model of NFX. The figure shows the density of carbohydrates, contoured at a level of 1.5 .

The above figures are reprinted by permission from the Federation of European Biochemical Societies: Eur J Biochem (2003, 270, 1399-1412) copyright 2003.

Figures were selected by the author.