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[目的]谷氨酰胺磷酸核糖焦磷酸转酰胺酶（ASE）在植物嘌呤合成中发挥着关键作用,本研究的目的是详细揭示杨树ASE蛋白的生化功能特性。[方法]通过半定量RT-PCR、蛋白质亚细胞定位以及测定纯化蛋白的催化活性等方法来研究其在体外的生化功能,进一步通过互补拟南芥缺失突变体（atase2）来研究杨树ASE基因的体内生物学功能。[结果]从杨树基因组中鉴别出2个ASE基因,序列分析发现它们之间有很高的蛋白质序列相似性。半定量RT-PCR分析发现两个杨树ASE基因在根、茎、叶和芽中均表达。蛋白质亚细胞定位分析发现杨树ASE蛋白均定位在叶绿体中,而且两个杨树ASE蛋白均能完全互补拟南芥atase2突变体的表型。酶学性质分析表明,杨树两个ASE蛋白均能催化5-磷酸核糖-α-焦磷酸生成5-磷酸核糖-β-胺。[结论]本研究预示着两个杨树ASE蛋白在嘌呤合成中均发挥着重要作用。

[Objective] The purpose of this study is to understand the biochemical functions of glutamine phosphoribosyl pyrophosphate amidotransferase (ASE) .[Method] By sq-PCR, protein subcellular location and catalytic activity determination of purified protein, the in vitro biochemical functions of ASE proteins were studied, and furthermore, the deletion mutant of Arabidopsis by complementation (atase2) were used to study the in vivo biological functions of poplar ASE genes. [Result] Two ASE genes were identified from Populus trichocarpa. The protein sequence analysis revealed a high sequence similarity between the two ASEs. These ASE genes were expressed in root, stem, leaf and bud tissues. The results of protein subcellular localization analysis showed that Populus ASE proteins were localized in chloroplasts. The Populus ASE genes could completely complement the function of Arabidopsis atase mutant. The recombinant Populus ASE proteins were expressed in E. coli and purified by Ni-affinity chromatography. Populus AS