CAJ | 학술논문

在细菌、真菌及植物中,分支酸是一种位于关键分叉点上的中间代谢物,是所有芳香族氨基酸合成的共同前体.它可在双功能酶分支酸变位酶(CM)和预苯酸脱水酶(PDT)的催化下合成苯丙氨酸,在另一个双功能酶分支酸变位酶和预苯酸脱氢酶(PDH)的催化下合成酪氨酸.前者被称为P蛋白,后者被称为T蛋白.大肠杆菌P蛋白和T蛋白有着类似的结构,P蛋白由CMp、PDT和调节结构域3个独立结构域组成,其变构调节因子是苯丙氨酸.T蛋白只有CMt和PDH两个独立结构域组成,起变构调节作用的调节结构域与PDH密不可分,其变构调节因子是酪氨酸.为了研究P蛋白和T蛋白的调节结构域的变构调节作用,应用融合蛋白技术将P蛋白和T蛋白的调节结构域进行了互换.结果发现,互换了的调节结构域仍然具有变构调节作用,而且调节结构域的互换导致了变构调节因子的互换,说明调节结构域对酶活性的调节作用是非专一的,而其R结构域与调节因子的结合却是专一的.
재세균、진균급식물중,분지산시일충위우관건분차점상적중간대사물,시소유방향족안기산합성적공동전체.타가재쌍공능매분지산변위매(CM)화예분산탈수매(PDT)적최화하합성분병안산,재령일개쌍공능매분지산변위매화예분산탈경매(PDH)적최화하합성락안산.전자피칭위P단백,후자피칭위T단백.대장간균P단백화T단백유착유사적결구,P단백유CMp、PDT화조절결구역3개독립결구역조성,기변구조절인자시분병안산.T단백지유CMt화PDH량개독립결구역조성,기변구조절작용적조절결구역여PDH밀불가분,기변구조절인자시락안산.위료연구P단백화T단백적조절결구역적변구조절작용,응용융합단백기술장P단백화T단백적조절결구역진행료호환.결과발현,호환료적조절결구역잉연구유변구조절작용,이차조절결구역적호환도치료변구조절인자적호환,설명조절결구역대매활성적조절작용시비전일적,이기R결구역여조절인자적결합각시전일적.
Chorismic acid is a mid-metabolite that plays a central role in the metablism process distributing in the bacterium, epiphyte and plants. It is a common precursor substance of the all aromatic amino acids that can turn into phenylalanine and tyrosine catalyzed by bi-functional enzyme chorismate mutase (CM)-prephenate dehydratase (PDT) and chorismate mutase-prephenate dehydrogenase (PDH) respectively. CMp-PDT with its regulate domain Rp were called P-protein and CMt-PDH with its regulate domain Rt were called T-protein. P-protein and T-protein from E. coli. have a similar structure, both of which contained three domains: CMp, PDT, Rp in P-protein and CMt, PDH, Rt in T-protein. P-protein and T-protein are regulated by their effectors phenylalanine and tyrosine respectively through binding to their Rp and Rt domains. Rp and Rt domains were switched between P-protein and T-protein by cloning of chimeric proteins. The results showed that regulatory effects were switched along the switch of R domains and the switch of the regulatory domains lead to the switch of effectors. It means that the combination of the regulatory domain and the effector is specific and the regulating of the regulatory domain to the enzyme activity is non-specific. This property of R domains may make them possible molecular elements in the study of molecular machines.