原子力显微镜力谱研究大肠杆菌启动子与RNA聚合酶的相互作用

【目的】本研究通过原子力显微镜(AFM)力谱技术研究了大肠杆菌启动子与RNA聚合酶(RNAp)间的相互作用,目的是建立一种高效的体外表征启动子的新方法。【方法】优化了用于单分子AFM力谱分析的蛋白固定化策略,建立AFM力谱分析启动子的策略,以缺失识别启动子序列的σ亚基核心RNA聚合酶(RNAp-C)为对照,研究启动子/RNAp间相互作用的特异性。最后比较了序列较典型的Ls1启动子和缺失–10区的Ls2启动子的力谱。【结果】基于建立的方法,验证了Ls1与大肠杆菌RNAp结合的特异性,其相互作用力为(331.10±5.10)p N。与Ls1相比,Ls2启动子与RNAp结合显著减少。利用启动子探针质粒,以报告基因cat的表达产物氯霉素乙酰转移酶(CAT)的酶活验证Ls1、Ls2启动子强度,分别为(181.70±4.10)、(0.30±0.20)U/mg。【结论】本研究建立的基于AFM力谱技术的启动子分析技术,是一种高效的、直接定量表征启动子活性的新方法。

Atomic force microscope based force spectroscopy as tool to study the interaction between Escherichia coli promoter and RNA polymerase

[Objective] To establish an efficient method for promoter characterization, the interaction between E. coli promoter and RNA polymerase (RNAp) was studied by atomic force microscope (AFM) based force spectroscopy.[Methods] Protein immobilization was optimized, and the specific promoter/RNAp interaction was verified using core-RNAp (RNAp-C) as control. The force spectrum of promoter Ls2, lack of -10 region of Ls1, was studied.[Results] Based on the established method, the specific interaction between promoter Ls1 and RNAp was studied, and the rupture force was measured as (331.10±5.14) pN. Ls2 showed significantly less binding events towards RNAp compared with Ls1. Using promoter-probe plasmid, the activities of Ls1 and Ls2 were verified by reporter gene-cat, which were (181.73±4.08) U/mg and (0.33±0.21) U/mg, respectively.[Conclusion] A novel promoter analysis method based on AFM force spectroscopy was established. The results demonstrated this method can be applied in quantitative characterization of promoter with high efficacy and reliability.