植物谷胱甘肽转硫酶及其与杂草抗药性的关系

Plant Glutathione S-Transferases and Its Relation to Herbicide-Resistance of Weed

谷胱甘肽转硫酶(GSTs)是由一个超基因家族编码的广泛存在于好氧生物中的多功能蛋白。GST通常都是成簇地非随机地分布在染色体中。每种植物GSTs家族一般有25～60个成员。根据植物GST序列的相似性、基因结构、蛋白中的活性位点,分成6类(6个家族)。其中Phi类和Tau类是植物特有的常见类型,Zeta和Theta类通常存在于动物中。GST基因尽管在序列和功能上表现很高的多样性,但它们都有相似的空间结构。大部分GST都是胞质型的,通常以二聚体的形式发挥功能,具有亲电疏水性异物谷胱甘肽化酶、谷胱甘肽依赖的异构化酶、谷胱甘肽过氧化物酶和还原毒性有机过氧化物酶等酶学功能,还以非酶学结合的方式来保护植物细胞,例如作为内源性毒物的植物激素或类黄酮类物质的配体(分子伴侣或载体)与GST结合。酶学和非酶学这两种功能都与异物或有毒内源性物质的解毒和防止细胞氧化损伤有关。除草剂的谷胱甘肽化是杂草产生抗药性的机制之一。谷胱甘肽通过过氧化物酶功能消除除草剂造成的氧化逆境而间接参与杂草抗药性。

Glutathione S - transferases （GSTs） is a kind of protein with multiple function widely presented in the aerobic species encoded by super gene families. GST genes are usually distributed non - randomly in the chromosome in clusters. There are generally 25 - 60 members in GSTs family of each plant species, which can be grouped into six classes accord- ing to the GST sequence similarity, gene organization and active site residues in the protein. The Phi and Tau classes are specific common types in plant,while Zeta and Theta classes are usually found in animals. Although GST genes present a high diversity in the sequence and function, they have similar spatial structure. Most of the GSTs are cytosolic, and usually act in the form of a dimmer, and have some function of enzymes such as electrophilic and hydrophobic foreign glutathione synthefase, glutathione -dependent isomerization dismutase, glutathione peroxidase and organic peroxidase with restore toxicity, etc. They also protect plant cells in non - enzymatic binding manner, for example, the ligand （chaperone or carrier） of plant hormones or flavonoid as substances of endogenous poison can be combined with GSTs. Those two kinds of enzymology and non - enzymatic function are associated with of xenobiotics or endogenous poison detoxification and prevention of cells oxidative injury. Herbicide S - glutathionylation is one of mechanisms for evolution of herbicide. Glutathione indirectly involved in the process of weeds herbicide - resistance via peroxidase function to eliminate the oxidative stress caused by herbicides.