2BNJ

The xylanase TA from Thermoascus aurantiacus utilizes arabinose decorations of xylan as significant substrate specificity determinants.

Summary for 2BNJ

• Entry DOI: 10.2210/pdb2bnj/pdb
• Related: 1GOK 1GOM 1GOO 1GOQ 1GOR 1I1W 1I1X 1K6A 1TUX
• Descriptor: ENDO-1,4-BETA-XYLANASE, alpha-L-arabinofuranose-(1-3)-beta-D-xylopyranose-(1-4)-beta-D-xylopyranose, 3-(4-HYDROXY-3-METHOXYPHENYL)-2-PROPENOIC ACID, ... (4 entities in total)
• Functional Keywords: xylanase, glycosidase, hydrolase, pyrrolidone carboxylic acid, xylan degradation
• Biological source: THERMOASCUS AURANTIACUS
• Total number of polymer chains: 1
• Total formula weight: 33457.29

Authors

Vardakou, M.,Murray, J.W.,Flint, J.,Christakopoulos, P.,Lewis, R.J.,Gilbert, H.J. (deposition date: 2005-03-25, release date: 2005-09-07, Last modification date: 2024-11-13)

Primary citation

Vardakou, M.,Flint, J.,Christakopoulos, P.,Lewis, R.J.,Gilbert, H.J.,Murray, J.W.
A Family 10 Thermoascus Aurantiacus Xylanase Utilizes Arabinose Decorations of Xylan as Significant Substrate Specificity Determinants.
J.Mol.Biol., 352:1060-, 2005

PubMed Abstract: Xylan, which is a key component of the plant cell wall, consists of a backbone of beta-1,4-linked xylose residues that are decorated with arabinofuranose, acetyl, 4-O-methyl d-glucuronic acid and ferulate. The backbone of xylan is hydrolysed by endo-beta1,4-xylanases (xylanases); however, it is unclear whether the various side-chains of the polysaccharide are utilized by these enzymes as significant substrate specificity determinants. To address this question we have determined the crystal structure of a family 10 xylanase from Thermoascus aurantiacus, in complex with xylobiose containing an arabinofuranosyl-ferulate side-chain. We show that the distal glycone subsite of the enzyme makes extensive direct and indirect interactions with the arabinose side-chain, while the ferulate moiety is solvent-exposed. Consistent with the 3D structural data, the xylanase displays fourfold more activity against xylotriose in which the non-reducing moiety is linked to an arabinose side-chain, compared to the undecorated form of the oligosacchairde. These data indicate that the sugar decorations of xylans in the T.aurantiacus family 10 xylanase, rather than simply being accommodated, can be significant substrate specificity determinants.

PubMed: 16140328
DOI: 10.1016/J.JMB.2005.07.051

Experimental method

X-RAY DIFFRACTION (1.6 Å)