Kapitonov V V, Jurka J
Genetic Information Research Institute, 2081 Landings Drive, Mountain View, CA 94043, USA.
Proc Natl Acad Sci U S A. 2001 Jul 17;98(15):8714-9. doi: 10.1073/pnas.151269298. Epub 2001 Jul 10.
All eukaryotic DNA transposons reported so far belong to a single category of elements transposed by the so-called "cut-and-paste" mechanism. Here, we report a previously unknown category of eukaryotic DNA transposons, Helitron, which transpose by rolling-circle replication. Autonomous Helitrons encode a 5'-to-3' DNA helicase and nuclease/ligase similar to those encoded by known rolling-circle replicons. Helitron-like transposons have conservative 5'-TC and CTRR-3' termini and do not have terminal inverted repeats. They contain 16- to 20-bp hairpins separated by 10--12 nucleotides from the 3'-end and transpose precisely between the 5'-A and T-3', with no modifications of the AT target sites. Together with their multiple diverged nonautonomous descendants, Helitrons constitute approximately 2% of both the Arabidopsis thaliana and Caenorhabditis elegans genomes and also colonize the Oriza sativa genome. Sequence conservation suggests that Helitrons continue to be transposed.
迄今报道的所有真核生物DNA转座子都属于通过所谓“剪切和粘贴”机制进行转座的单一元件类别。在此，我们报道了一类以前未知的真核生物DNA转座子——Helitron，其通过滚环复制进行转座。自主Helitron编码一种5'至3' DNA解旋酶以及与已知滚环复制子所编码的核酸酶/连接酶相似的酶。类Helitron转座子具有保守的5'-TC和CTRR-3'末端，并且没有末端反向重复序列。它们含有16至20个碱基对的发夹结构，从3'端起被10 - 12个核苷酸隔开，并精确地在5'-A和T-3'之间转座，对AT靶位点不进行修饰。与它们众多分化的非自主后代一起，Helitron在拟南芥和秀丽隐杆线虫基因组中均占约2%，并且也在水稻基因组中存在。序列保守性表明Helitron仍在继续转座。
