细菌转座子Tn5转座机理的研究进展

Research development of Tn5 transposition mechanism

细菌转座子Tn5属于IS4家族,两端具有两段倒置的IS50序列。右末端(IS50R)编码转座酶(Tnp)和一个阻遏转座蛋白(Inh);左末端(IS50L)存在一个赭石突变,不能编码有功能的转座酶。Tn5属于非复制型转座子,被广泛应用于发现新基因、分析基因功能和构建突变体库。但是在相当长的一个时期里,人们对其转座机理、转座热点等问题并不完全清楚。随着在体外具有活性的转座酶TnpEK/LP(同时含有E54K和L372P两个突变点)的成功构建,以及对Tnp催化中心三维结构的深入研究,近几年对Tn5的转座机理才有了深刻了解。本文综述了Tn5的转座机制、Tnp结构、DDE模体和转座频率调控等研究的最新进展。

The bacterial transposon Tn5, belonging to IS4 family, has two inverted repeats of IS50 at each end. The right end (IS50R) encodes two proteins (Tnp and Inh), and the ocher mutation in the left end renders inactive by prematurely terminating the tansposase. With the feature of nonreplicative function, Tn5 has been widely used in discovering new genes,analyzing the functions of genes and constructing mutant pools, but in a considerably long period, People didn't have enough knowledge about its transposition mechanism, the hotspot of Tn5 insertion and other concerned issues. With successfully constructing a hyperactive transposase in vitro which contains the point mutations E54K and L372P, and furthering the research on the three-dimensional structures of the catalytic core domains of Tnp, the breakthrough progress in Tn5's research has been achieved in recent years. This paper reviews the latest achievements in the research of Tn5 transposition mechanism, the structure of Tnp, DDE motif and the control of transposition frequency.