5HQC

A Glycoside Hydrolase Family 97 enzyme R171K variant from Pseudoalteromonas sp. strain K8

5HQC の概要

• エントリーDOI: 10.2210/pdb5hqc/pdb
• 関連するPDBエントリー: 5HQ4 5HQA 5HQB
• 分子名称: Glycoside Hydrolase Family 97 enzyme, CHLORIDE ION, MAGNESIUM ION, ... (8 entities in total)
• 機能のキーワード: glucoside hydrolase, family 97, chloride, hydrolase
• 由来する生物種: Pseudoalteromonas sp. K8
• タンパク質・核酸の鎖数: 1
• 化学式量合計: 76153.64

構造登録者

Li, J.,He, C.,Xiao, Y. (登録日: 2016-01-21, 公開日: 2017-01-11, 最終更新日: 2023-11-08)

主引用文献

He, C.,Li, J.,Li, W.,Xue, Y.,Fang, Z.,Fang, W.,Zhang, X.,Wang, X.,Xiao, Y.
Structures of PspAG97A alpha-glucoside hydrolase reveal a novel mechanism for chloride induced activation.
J. Struct. Biol., 196:426-436, 2016

PubMed Abstract: Here we report the first crystal structure of a secretory α-glucoside hydrolase isolated from Pseudoalteromonas sp. K8, PspAG97A, which belongs to glycoside hydrolase family 97 and exhibits halophilic property. PspAG97A lacks an acidic surface, that is considered essential for protein stability at high salinity. Interestingly, PspAG97A unusually contains a chloride ion coordinated by the guanidinium group of Arg171 and the main chain amide groups of Tyr172 and Glu173 at the active site. The structures of PspAG97A complexed with acarbose and panose demonstrate that residues Glu173, Arg171 and Asn170 for subsite +1 decide the substrate specificity of the enzyme for the α-1,6-glucosidic linkage. Structural alterations observed in the R171K variant and enzyme kinetic experiments focusing on chloride assisted activation suggest that the active site chloride serves to properly orient Glu173, Arg171 and Asn170 to facilitate substrate recognition. Furthermore, the chloride assists the binding of Glu173 to the conserved calcium ion and plays an essential role in properly positioning the base catalyst Glu456. In sum, our results provide valuable insight into the structural basis of protein halophilicity.

PubMed: 27645700
DOI: 10.1016/j.jsb.2016.09.009

実験手法

X-RAY DIFFRACTION (2.001 Å)