靶向转化生长因子-βⅡ型受体核酸适配子结合位点预测及相关验证研究

Targeting transforming growth factor-βreceptorⅡ aptamer binding sites prediction and validation studies

目的预测转化生长因子-βⅡ型受体(TRβⅡ)胞外段蛋白与靶向适配子S58的结合位点,并在体外进行验证,证实S58的结构稳定性。方法通过适配子ssDNA序列建立其三维结构,在蛋白质数据库搜索受体蛋白TRβⅡ胞外段的晶体结构,运用计算机辅助技术对两个分子进行对接实验,根据结果指导剪切优化适配子结构,分别用生物传感器技术及蛋白免疫印迹法验证其亲和力。结果核酸适配子ssDNA S58与TRβⅡ胞外段蛋白结合的可信位点包括位点Ⅰ(T4、T5、G6、C7)、位点Ⅱ(G13、A14、T15、C16、G17、C18)、位点Ⅲ(T31、G32、T33、C34)及位点Ⅳ(G40、A41、T42、T43、T44、G45、G46)。S58与TRβⅡ胞外段蛋白的亲和力高,S58的α-平滑肌肌动蛋白(α-SMA)表达明显较DMEM对照降低(P<0.05),根据结果剪切适配子S58后得到优化后的ssDNA亲和力、α-SMA表达均不如S58。结论核酸适配子S58为受体蛋白TβRⅡ的高特异性分子,具有一定稳定性,任何结构的改变均会降低与TβRⅡ的亲和力。计算机辅助的分子对接技术成为一项探索分子间作用的重要手段,为医学基础研究提供了良好的理论依据。

Objective To predict the binding sites of transforming growth factor-βreceptor Ⅱ （TβRⅡ ） ectodomain and the aptamer S58 specifically targeted TβRⅡ ,and to confirm the structure stability of the aptamer S 58 in vitro .Methods We created three-dimensional structure by utilizing ssDNA aptamer sequences ,the crystal structure of the TβRⅡ was searched by protein data bank database .According to the results of the molecular docking experiments on aptamer S 58 and TβRⅡ ectodomain ,we sheared the aptamer sequences ,then verified its affinity respectively by biosensor technology and Western blot .Results Binding sites of aptamers S58 and TRβⅡ ectodomain included site Ⅰ（T4 ,T5 ,G6 ,C7） ,site Ⅱ（G13 ,A14 ,T15 ,C16 ,G17 ,C18 ） ,site Ⅲ （T31 ,G32 , T33 ,C34） and site Ⅳ（G40 ,A41 ,T42 ,T43 ,T44 ,G45 ,G46） .We validated the high affinity between aptamer S58 and TRβⅡ ectodo-main .The expression of α-smooth muscle actin（α-SMA） protein in the human tenon′s capsule fibroblasts was descended obviously after the experiment of the aptamer S58 in comparing with the control of DMEM （P＆lt; 0 .05） .But the new ssDNA by shear the aptamer ssDNA S58 according to the results were poor than aptamers S58 .Conclusion The aptamer S58 targeted TβRⅡ was high-ly specific with a certain stability ,any changing of structure will reduce the affinity of TβRⅡ .Computer-aided molecular docking technology has become an important means of an exploratory intermolecular interaction ,and can provides a good theoretical basis on medical research .