Tn7转座子核苷酸蛋白复合体结构生物学研究

Transposable Elements (TEs) or transposons are DNA sequences that can re-locate their position within the genome. Transposons are genetic elements which have colonized in living organisms from bacteria to plants and mammals. Genome size,gene content, gene order, centromere function, and numerous other aspects of nuclear biology are driven by TE activity. The interactions between transposition proteins and the transposon ends have been analyzed at the biochemical level for some transposons, only a few transposons such as Tn5 and Hermes have been cocrystallized with transposon ends DNA. Tn7 is unique among transposable elements because it encodes five transposition genes, TnsABCDE, that mediate two transposition pathways. Tn7 transposition requires the assembly of a nucleoprotein complex containing four self-encoded proteins, transposon ends, and target DNA.Tn7 is unique system for cataloguing the relationships between protein-protein,protein-DNA and DNA-DNA in nucleoprotein complex. But the complicative of Tn7 transpososome has precluded us from cocrystallizing the proteins with DNA. We will initiate a structure study of Tn7 transpososome using Cryo-electron microscopy (cryo-EM). Our data will provide new.insights on how Tn7 transposase recognizes Tn7 transposon ends DNA and target DNA.

转座子是可以在基因组之间转移的一段DNA序列，它存在各种生物物种基因组当中，在生物基因组多样性进程中起关键作用，基因组体积大小、基因内容、排列顺序、着丝点生物功能等都是由转座子作用来推动的。目前多数转座酶与转座子DNA的互作研究都停留在生化水平，只有两个转座子Tn5和Hermes获得了转座酶和DNA的复合晶体结构。转座子Tn7编码五个转座酶TnsABCDE，介导两种转座通道。Tn7转座反应需要其自身编码的四个蛋白质和转座子两臂DNA以及靶DNA一起组成核苷酸蛋白复合体。Tn7是研究核苷酸蛋白复合体中蛋白互作、蛋白与DNA互作以DNA与DNA互作的独特模型，但由于Tn7转座子的多酶体系复杂性使得Tn7转座酶与DNA共结晶极为困难。我们拟采用冷冻电镜技术进行Tn7子核苷酸蛋白复合体结构生物学研究。该研究将为我们更进一步研究Tn7转座酶与DNA的互相作用提供新的研究方向。