细菌双杂交系统的改进

The modified bacterial two-hybrid system

摘要:

解析蛋白质之间的相互作用，对理解调控和代谢等生物学过程具有重要意义。其中基于互补腺苷酸环化酶功能的细菌双杂交系统是一种研究蛋白质之间相互作用的有效手段。本文在利用该系统时发现存在假阳性高的缺陷。进一步报告基因活性分析表明产生假阳性的原因是不同克隆的生理状态影响了LacZ的输出，即lacZ启动子除了受cAMP信号分子的控制，还受到其他调控蛋白的直接或间接的调控。为了降低生理因素对报告基因的影响，我们向该系统引入用多拷贝lacZ启动子控制的gfp报告基因。这不仅通过增加lacZ启动子的数量，弱化了生理因素的影响；还实现了第二个报告基因gfp与lacZ同时报告蛋白质之间的相互作用情况，提高了输出的准确性。系统的实验验证表明，我们改进的细菌双杂交系统的灵敏性确实得到大幅提高。

Abstract:

Bacterial two-hybrid system is a newly developed method for studying protein-protein interactions. However, in our studies of the interaction of regulatory proteins in Streptomyces, it was found that the bacterial two-hybrid system is not sensitive enough by the blue-and-white selection on X-gal plate. To overcome this drawback, the reason of false positive clone was firstly determined, which was the disturbance of other direct or indirect regulation on lacZ promoter. Then the disturbance was diluted by introducing multicopy lacZ promoter, which drive another reporter gene gfp. By such design, the sensitivity of the modified bacterial two-hybrid system was significantly inproved and the two different reporters also help to decrease the rate of the false positive clones. Further the evaluation of the modified bacterial two-hybrid system indicated that the sensitivity was significantly improved.