人重组S100A8蛋白适配体的筛选和结构分析

Screening and structure analysis of the aptamers against human recombinant S100A8 protein

目的:筛选人重组S100A8蛋白特异性的适配体。方法:采用配体指数级富集系统进化(systematic evolu-tion of ligand by exponential enrichment,SELEX)技术,以人重组S100A8蛋白为靶蛋白,以微孔板为筛选介质,从体外合成的随机单链DNA文库中筛选其适配体。利用生物素-链霉亲和素-辣根过氧化物酶系统检测每轮单链DNA文库与靶蛋白的亲和力直至亲和力的上升趋于饱和,将最后一轮筛选产物克隆测序,并进行生物信息学分析。结果:经过11轮筛选,单链DNA文库与人重组S100A8蛋白的亲和力趋向稳定,将第11轮筛选产物克隆测序,对获得的30个适配体进行分析。一级结构分析显示30个适配体并无共同的保守序列,但有3对适配体序列完全一致。二级结构预测分析表明,茎环和口袋结构为主要的结构形式,提示其可能是适配体与人重组S100A8蛋白特异性结合的基础。根据茎环和口袋的相对比例可将30个适配体分为4组,其中第1组中35号适配体与人重组S100A8蛋白亲和力最高。结论:获得了与人重组S100A8蛋白特异性结合的适配体群,为后续适配体的应用研究以及S100A8蛋白功能的研究奠定了基础。

Objective： To obtain and characterize the single-stranded DNA（ssDNA） aptamers of human recombinant S100A8 protein.Methods： According to systematic evolution of ligands by exponential enrichment（SELEX） method,an ssDNA random library was subjected to 11 rounds of selection against human recombinant S100A8 protein.Using a biotin-strepavidin-HRP detecting system,the binding capacity of ssDNA to targeted protein from each round was monitored,until the binding level reached a saturation state.Then the ssDNA from the last cycle were cloned and sequenced,and the sequences were further analyzed by programs of bioinformatics.Results： After 11 cycles of selection,30 clones were selected randomly and sent to sequence analysis.A unique conserved sequence was not obtained among the 30 aptamers by the primary structure analysis,but three aptamers were found identical with three other aptamers respectively.The secondary structure analysis revealed that stem-loop and pocket were the main motifs,indicating that they may play a key role in the binding of aptamers to human recombinant S100A8 protein.According to the ratio of stem-loop to pocket,30 aptamers were divided into 4 groups,and the affinity of aptamer No.35 from group Ⅰ was the highest.Conclusion： Aptamers against human recombinant S100A8 protein were identified by SELEX method,which laid the basis for the further application of the aptamers and the function study of human recombinant S100A8 protein.