Thioredoxin和線形噬菌體f1 Gene I蛋白的交互作用之研究

Abstract

Thioredoxin是一個任何型態細胞中皆有，且具有許多功能的熱穩定蛋 白。常見的功能是在細胞內，扮演氧化還原蛋白的角色，例如 thioredoxin參與核糖核甘酸二磷酸(ribonucleotide diphosphate)的還 原、動物細胞中的胰島素還原劑、高等植物細胞葉綠體中某些酵素的活化 。噬菌體T7去氧核糖核酸聚合酵素(T7 DNA polymerase)之次單元、及線 形噬菌體f1(filamentous bacteriophage f1)所須之蛋白。對於大腸桿菌 Thioredoxin影響線形噬菌體f1生長的機制，目前並不是非常清楚，只知 其影響的步驟可能發生在線形噬菌體f1組裝子代移出宿主細胞時。而一些 遺傳實驗證據顯示，thioredoxin可能與線形噬菌體f1的Gene I蛋白有交 互作用。線形噬菌體f1為單股去氧核糖核酸病毒(single-stranded DNA virus)，對於帶有F質體(F+)的大腸桿菌有專一性。f1構型與遺傳物質為 核糖核酸(RNA)的煙草鑲嵌病毒(TMV)類似，遺傳物質外由許多相同單元之 殼蛋白包裹；另外，f1的感染也與許多動物病毒相似，皆不會造成宿主死 亡。一些動物病毒感染細胞皆與Thioredoxin有關聯，但作用機制現仍不 甚了解。本研究的目的是希望藉由研究Thioredoxin及Gene I蛋白是否能 夠交互作用以了解thioredoxin在線形病毒生長的作用機轉及所扮演的角 色。經由活體內酵母菌雙雜交系統實驗結果呈現藍色可知，Thioredoxin 及Gene I蛋白確實有交互作用。 Thioredoxin is a multifunctional heat stable protein found in all cell types. It appears to play a variety of roles in different cell types. In E. coli, it is a general protein disulfide reductant. It serves as the reductant for systhesis of deoxyribonucleotides and is an effective reductant of insulin in animal cells. The protein also acts as an activator of certain enzymes of carbon dioxide fixation in the chloroplasts of higher plants. It may also be involved in activation of the glucocorticoid receptor, phage T7 growth, and filamentous phage assembly. Filamentous phage f1 is a single- stranded circular DNA virus. It is specific for the F+ strains of Escherichia coli. In common with other filamentous bacteriophages, these viruses exhibit unusual mechanisms of replication and maturation and in many respects resemble endosymbiotic animal viruses rather than typical lytic bacteriophages. Thioredoxin is in fact related to the infection of animal cells by some animal viruses. We are interested in studying the relationship between thioredoxin and virus infection. In this study, we start with filamentous phage f1. Genetic studies have indicated that thioredoxin can interact with Gene I protein of filamentous phage f1. In this study we investigate whether thioredoxin can interact with Gene I protein of the phage by using yeast two-hybrid system. The results show that thioredoxin indeed interacts with filamentous phage f1 Gene I protein.