Structure of a Drosophila sigma class glutathione S-transferase reveals a novel active site topography suited for lipid peroxidation products
Structure of a Drosophila sigma class glutathione S-transferase reveals a novel active site topography suited for lipid peroxidation products
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DOI：
10.1016/s0022-2836(02)01327-x
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发表时间：
2003-02-07
影响因子：
5.6
通讯作者：
Gros, P
中科院分区：
文献类型：
--
作者：
Agianian, B;Tucker, PA;Gros, P
昆虫谷胱甘肽-S-转移酶（GST）分为三类，I，II和最近的III; I类（Delta类）酶与III类成员一起参与赋予杀虫剂抗性。然而，II类（Sigma类）GST的特征很差，其确切的生物学功能仍然难以捉摸。果蝇谷胱甘肽S-转移酶-2（GST-2）（DmGSTS 1 -1）是一种II类酶，以前发现与昆虫间接飞行肌特异性相关。最近显示GST-2对脂质过氧化产物4-羟基壬烯醛（4-HNE）表现出相当大的缀合活性，提高了它在飞行肌肉中具有主要抗氧化作用的可能性。在这里，我们报告GST-2的晶体结构在1.75埃分辨率。GST-2二聚体显示了典型的GST折叠，其中谷胱甘肽（GSH）仅在两个结合位点中的一个中有序。虽然GSH结合模式与其他GST结构相似，但螺旋α 6的独特取向产生了一种新的亲电底物结合位点（H位点）形貌，基本上是平坦的，没有突出的疏水结合口袋，这是其他GST的H位点的特征。H-位点在带电/极性和疏水残基的分布中显示方向性，产生结合表面，其解释了对双极性过氧化产物的选择性，极性结合区域由残基Y208、Y153和R145形成，疏水结合区域由残基V57、A59、Y211和C-末端V249形成。提出了一个基于结构的4-HNE结合模型。该模型表明，残基Y208，R145和可能的Y153可能是参与催化的关键残基。(C)2003爱思唯尔科技有限公司版权所有。
Insect glutathione-S-transferases (GSTs) are grouped in three classes, I, II and recently III; class I (Delta class) enzymes together with class III members are implicated in conferring resistance to insecticides. Class II (Sigma class) GSTs, however, are poorly characterized and their exact biological function remains elusive. Drosophila glutathione S-transferase-2 (GST-2) (DmGSTS1-1) is a class II enzyme previously found associated specifically with the insect indirect flight muscle. It was recently shown that GST-2 exhibits considerable conjugation activity for 4-hydroxynonenal (4-HNE), a lipid peroxidation product, raising the possibility that it has a major anti-oxidant role in the flight muscle. Here, we report the crystal structure of GST-2 at 1.75 Angstrom resolution. The GST-2 dimer shows the canonical GST fold with glutathione (GSH) ordered in only one of the two binding sites. While the GSH-binding mode is similar to other GST structures, a distinct orientation of helix alpha6 creates a novel electrophilic substrate-binding site (H-site) topography, largely flat and without a prominent hydrophobic-binding pocket, which characterizes the H-sites of other GSTs. The H-site displays directionality in the distribution of charged/polar and hydrophobic residues creating a binding surface that explains the selectivity for amphipolar peroxidation products, with the polar-binding region formed by residues Y208, Y153 and R145 and the hydrophobic-binding region by residues V57, A59, Y211 and the C-terminal V249. A structure-based model of 4-HNE binding is presented. The model suggest that residues Y208, R145 and possibly Y153 may be key residues involved in catalysis. (C) 2003 Elsevier Science Ltd. All rights reserved.