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Structure and Function of Tpn transposable elements in the Japanese morning glory

日本牵牛花Tpn转座因子的结构与功能

基本信息

批准号：
11640621
负责人：
NITASAKA Eiji
金额：
$ 2.43万
依托单位：
KYUSHU UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11640621/
关键词：
Transposon Tpn the Japanese morning glory Ipomoea AP2 CAF

项目摘要

Some mutations of the Japanese morning glory were known to be unstable somatically and germinally as caused by insertions of transposable elements. Until now, transposable elements that cause mutable phenotypes have been isolated from several genes. All of these elements belong to the En/Spm family by their structures. They all carried common 28-bp terminal inverted repeats (TIRs) and subterminal regions with many repeats. These transposable elements with common terminal sequences are termed Tpn1 family. All of them thought to be nonautonomous elements and these elements in mutable alleles are mobilized by autonoumous elements. The copy number of Tpn1 family was estimated between 500 and 1000 copies per haploid genome. Using probe of subterminal regions, we isolated more than 200 Tpn clones, and 128 clones were classified into 30 groups by their restriction maps. We decided the complete sequences of 19 representative Tpn clones from 30 groups. The comparison of their common regions among all Tpns indicates that the 5'-common regions including TIR, subterminal and non-repetitive regions are much longer than 3'-common regions. Interestingly, their internal sequences of Tpns were quite different among groups and were derived from host gene sequences. Another interesting feature of the Tpn1 family is the phylogenetic trees of each 5' and 3'common sequences did not make parallel relationships. By the linkage between 5'-subterminal regions and internal sequences, recombination events between different groups occurred in 3'-regions. We deduced a mechanism that Tpns incorporated host gene sequences in process of evolution from these findings. 3' protruding ends of Tpns mainly invades into homologous host genes as templates when Abortive Gap Repair events were occurred.

已知日本牵牛花的一些突变在躯体和胚芽上是不稳定的，这是由于插入了转座元件造成的。到目前为止，已经从几个基因中分离出了导致表型突变的转座元件。从结构上看，所有这些元件都属于EN/SPM家族。它们都带有共同的28bp末端反向重复序列(TIR)和含有许多重复序列的亚末端区域。这些具有共同末端序列的转座元件被称为Tpn1家族。所有这些都被认为是非自主的元素，而这些可变等位基因中的元素是由自体元素动员的。Tpn1家族的拷贝数估计在每个单倍体基因组500到1000个拷贝之间。利用亚端区探针分离了200多个TPN克隆，根据限制性内切酶图谱将128个克隆分为30个类群。我们测定了来自30个群体的19个具有代表性的TPN克隆的全序列。比较它们在所有TPN中的共同区域，发现包括TIR、亚末端和非重复区域在内的5‘-共同区域比3’-共同区域要长得多。有趣的是，它们的TPN的内部序列在不同的群体中有很大的不同，并且来自宿主基因序列。Tpn1家族的另一个有趣特征是，每个5‘和3’共同序列的系统发育树并不存在平行关系。通过5‘-亚端区和内部序列之间的连接，不同基团之间的重组事件发生在3’-区。根据这些发现，我们推测了TPNS在进化过程中整合宿主基因序列的机制。当发生流产的缺口修复事件时，TPNS的3‘端突出端主要以模板的形式侵入同源宿主基因。