A family 10 Thermoascus aurantiacus xylanase utilizes arabinose decorations of xylan as significant substrate specificity determinants

Vardakou, Maria and Flint, James and Christakopoulos, Paul and Lewis, Richard J. and Gilbert, Harry J. and Murray, James W. (2005) A family 10 Thermoascus aurantiacus xylanase utilizes arabinose decorations of xylan as significant substrate specificity determinants. Journal of Molecular Biology, 352 (5). pp. 1060-1067. ISSN 0022-2836

Full content URL: http://dx.doi.org/10.1016/j.jmb.2005.07.051

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Item Type:Article
Item Status:Live Archive

Abstract

Xylan, which is a key component of the plant cell wall, consists of a backbone of β-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-β1,4-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. © 2005 Elsevier Ltd. All rights reserved.

Keywords:xylan endo 1,3 beta xylosidase, article, catalysis, controlled study, crystal structure, enzyme activity, nonhuman, plant cell, priority journal, protein interaction, Thermoascus, Arabinose, Cell Wall, Chromatography, High Pressure Liquid, Crystallography, X-Ray, Endo-1,4-beta Xylanases, Eurotiales, Kinetics, Multigene Family, Plant Diseases, Protein Structure, Tertiary, Substrate Specificity, Xylans, Xylose, Thermoascus aurantiacus
Subjects:C Biological Sciences > C720 Biological Chemistry
Divisions:College of Science > School of Life Sciences
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ID Code:12471
Deposited On:08 Nov 2013 11:11

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