植物CACTA转座子的研究进展

转座子是染色体上可移动的DNA序列，根据转座机制可将其分为：通过RNA中间体进行转座的逆转录座子（Retrotransposon）和通过DNA中间体进行转座的转座子（Transposon）。En／Spm家族转座子是后者中的一类，它的末端反向重复序列（Terminal inverted repeats，TIRs）具有保守的5个碱基CACTA，所以通常又称为CACTA转座子。除此之外，其靶位点一般为3bp的同向重复（Target site duplication，TSD）；亚末端区域分布着若干正向或反向的重复序列（Subterminal repeat,STR）。迄今为止，CACTA转座子仅发现于植物基因组。过去一直认为由于其相对保守的转座机制而拷贝较少，但最近研究发现，该因子多拷贝存在于某些禾本科植物基因组中。由于该家族在基因组中分布的广泛性，具有用作分子指纹的应用前景。本文就其结构、转座机制和应用前景等做一综述。

Progress in Plant CACTA Elements

Transposable elements are DNA fragments that can insert new chromosomal locations. On the basis of the mechanism of transposition, transposable elements were divided into two classes. Class 1 elements were retroelements that used reverse transposase to transpose by an RNA intermediate, Class 2 elements or DNA transposons transposed directly from DNA to DNA. Of the Class 2 elements, CACTA superfamily, so far identified exclusively in plants and previously regarded as low-copy-transposon for the conserved mechanism of propagation, recently received considerable interest because of their increasing evidence reiterating their high copies in some plant genomes. This article aimed at outlining CACTA elements with regard to their structure, transposition, and utilization.