2UWF

Crystal structure of family 10 xylanase from Bacillus halodurans

2UWF の概要

• エントリーDOI: 10.2210/pdb2uwf/pdb
• 分子名称: ALKALINE ACTIVE ENDOXYLANASE, COPPER (II) ION, CALCIUM ION, ... (4 entities in total)
• 機能のキーワード: hydrolase, xylan degradation, xylanase structure, glycosidase, alkaliphilic, endoxylanase, bacillus halodurans, alkaline adaptation
• 由来する生物種: BACILLUS HALODURANS
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 41945.67

構造登録者

Mamo, G.,Thunnissen, M.,Hatti-Kaul, R.,Mattiasson, B. (登録日: 2007-03-21, 公開日: 2008-05-27, 最終更新日: 2023-12-13)

主引用文献

Mamo, G.,Thunnissen, M.,Hatti-Kaul, R.,Mattiasson, B.
An Alkaline Active Xylanase: Insights Into Mechanisms of High Ph Catalytic Adaptation
Biochimie, 91:1187-, 2009

PubMed Abstract: The alkaliphilic bacterium, Bacillus halodurans S7, produces an alkaline active xylanase (EC 3.2.1.8), which differs from many other xylanases in being operationally stable under alkaline conditions as well as at elevated temperature. Compared to non-alkaline active xylanases, this enzyme has a high percent composition of acidic amino acids which results in high ratio of negatively to positively charged residues. A positive correlation was observed between the charge ratio and the pH optima of xylanases. The recombinant xylanase was crystallized using a hanging drop diffusion method. The crystals belong to the space group P2(1)2(1)2(1) and the structure was determined at a resolution of 2.1 A. The enzyme has the common eight-fold TIM-barrel structure of family 10 xylanases; however, unlike non-alkaline active xylanases, it has a highly negatively charged surface and a deeper active site cleft. Mutational analysis of non-conserved amino acids which are close to the acid/base residue has shown that Val169, Ile170 and Asp171 are important to hydrolyze xylan at high pH. Unlike the wild type xylanase which has optimum pH at 9-9.5, the triple mutant xylanase (V169A, I170F and D171N), which was constructed using sequence information of alkaline sensitive xylanses was optimally active around pH 7. Compared to non-alkaline active xylanases, the alkaline active xylanases have highly acidic surfaces and fewer solvent exposed alkali labile residues. Based on these results obtained from sequence, structural and mutational analysis, the possible mechanisms of high pH stability and catalysis are discussed. This will provide useful information to understand the mechanism of high pH adaptation and engineering of enzymes that can be operationally stable at high pH.

PubMed: 19567261
DOI: 10.1016/J.BIOCHI.2009.06.017

実験手法

X-RAY DIFFRACTION (2.1 Å)