Turcotte Kime, Bureau Thomas
Department of Biology, McGill University, Montreal, Canada.
Genome. 2002 Feb;45(1):82-90. doi: 10.1139/g01-127.
The genomes of plants, like virtually all other eukaryotic organisms, harbor a diverse array of mobile elements, or transposons. In terms of numbers, the predominant type of transposons in many plants is the miniature inverted-repeat transposable element (MITE). There are three archetypal MITEs, known as Tourist, Stowaway, and Emigrant, each of which can be defined by a specific terminal inverted-repeat (TIR) sequence signature. Although their presence was known for over a decade, only recently have open reading frames (ORFs) been identified that correspond to putative transposases for each of the archetypes. We have identified two Stowaway elements that encode a putative transposase and are similar to members of the previously characterized IS630-Tc1-mariner superfamily. In this report, we provide a high-resolution phylogenetic analysis of the evolutionary relationship between Stowaway, Emigrant, and members of the IS630-Tc1-mariner superfamily. We show that although Emigrant is closely related to the pogo-like family of elements, Stowaway may represent a novel family. Integration of our results with previously published data leads to the conclusion that the three main types of MITEs have different evolutionary histories despite similarity in structure.
与几乎所有其他真核生物一样，植物基因组中含有各种各样的移动元件，即转座子。从数量上看，许多植物中转座子的主要类型是微型反向重复转座元件（MITE）。有三种典型的MITE，分别称为“旅行者”（Tourist）、“偷渡者”（Stowaway）和“移民者”（Emigrant），每种都可以通过特定的末端反向重复（TIR）序列特征来定义。尽管它们的存在已为人所知超过十年，但直到最近才鉴定出与每种原型的假定转座酶相对应的开放阅读框（ORF）。我们鉴定出了两个编码假定转座酶的“偷渡者”元件，它们与先前表征的IS630-Tc1-水手超家族的成员相似。在本报告中，我们对“偷渡者”、“移民者”以及IS630-Tc1-水手超家族的成员之间的进化关系进行了高分辨率系统发育分析。我们表明，尽管“移民者”与类pogo元件家族密切相关，但“偷渡者”可能代表一个新的家族。将我们的结果与先前发表的数据相结合，得出的结论是，尽管这三种主要类型的MITE在结构上相似，但它们具有不同的进化历史。
