4HKL

Crystal Structures of Mutant Endo-beta-1,4-xylanase II Complexed with substrate (1.15 A) and Products (1.6 A)

4HKL の概要

• エントリーDOI: 10.2210/pdb4hkl/pdb
• 関連するPDBエントリー: 2DFB 4HK8 4HK9 4HKO
• 分子名称: Endo-1,4-beta-xylanase 2, IODIDE ION (3 entities in total)
• 機能のキーワード: xylanase ii, xylohexaose, xylotriose, induced fit mechanism, oxocarbenium ion, hydrolase
• 由来する生物種: Trichoderma reesei
• 細胞内の位置: Secreted {ECO:0000269|Ref: P36217
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 21259.00

構造登録者

Langan, P.,Wan, Q.,Coates, L.,Kovalevsky, A. (登録日: 2012-10-15, 公開日: 2014-01-08, 最終更新日: 2024-02-28)

主引用文献

Wan, Q.,Zhang, Q.,Hamilton-Brehm, S.,Weiss, K.,Mustyakimov, M.,Coates, L.,Langan, P.,Graham, D.,Kovalevsky, A.
X-ray crystallographic studies of family 11 xylanase Michaelis and product complexes: implications for the catalytic mechanism.
Acta Crystallogr.,Sect.D, 70:11-23, 2014

PubMed Abstract: Xylanases catalyze the hydrolysis of plant hemicellulose xylan into oligosaccharides by cleaving the main-chain glycosidic linkages connecting xylose subunits. To study ligand binding and to understand how the pH constrains the activity of the enzyme, variants of the Trichoderma reesei xylanase were designed to either abolish its activity (E177Q) or to change its pH optimum (N44H). An E177Q-xylohexaose complex structure was obtained at 1.15 Å resolution which represents a pseudo-Michaelis complex and confirmed the conformational movement of the thumb region owing to ligand binding. Co-crystallization of N44H with xylohexaose resulted in a hydrolyzed xylotriose bound in the active site. Co-crystallization of the wild-type enzyme with xylopentaose trapped an aglycone xylotriose and a transglycosylated glycone product. Replacing amino acids near Glu177 decreased the xylanase activity but increased the relative activity at alkaline pH. The substrate distortion in the E177Q-xylohexaose structure expands the possible conformational itinerary of this xylose ring during the enzyme-catalyzed xylan-hydrolysis reaction.

PubMed: 24419374
DOI: 10.1107/S1399004713023626

実験手法

X-RAY DIFFRACTION (1.1 Å)