基于结构域活性分析的大肠杆菌T蛋白结构研究

大肠杆菌T蛋白含有三个结构域:分支酸变位酶、预苯酸脱氢酶和调节结构域。文章作者分段克隆了T蛋白的分支酸变位酶、预苯酸脱氢酶和调节结构域等片段,并对其进行了活性研究。研究发现,定位于N末端的分支酸变位酶结构域的比活性虽然不高,而稳定性较好;同时拥有调节结构域和预苯酸脱氢酶结构域的C末端片段,其预苯酸脱氢酶比活性的剩余百分率虽然高于分支酸变位酶结构域,但稳定性较差。作者进而表达了C末端切除38个氨基酸的T/1-336片段,发现预苯酸脱氢酶活性彻底丧失,而其分支酸变位酶和调节结构域的活性却基本保留。这说明T蛋白中分支酸变位酶结构域拥有一个相对独立、完整的结构,而预苯酸脱氢酶结构域和调节结构域交织共存,结构松散。

Domain Activity Based Protein Structure Study of T-protein from Escherichia coli

T-protein from Escherichia coli consists of three domains:chorismate mutase,prephenate dehydrogenase and a regulatory domain.In this study,the domain activity of several fragments from T-protein was evaluated.It was found that chorismate mutase domains' retained less activity,but was more stable,prephenate dehydrogenase domain retained more activity,but less stability.It lost all prephenate dehydrogenase activity when T-protein was expressed with 38 amino acids cut off at its C-terminus,but chorismate mutase and regulatory activity were both retained.It was concluded that chorismate mutase domain had an independent and compact structure,but prephenate dehydrogenase domain had a loose conformation interlaced with its regulatory domain.