End-to-end template jumping by the reverse transcriptase encoded by the R2 retrotransposon
End-to-end template jumping by the reverse transcriptase encoded by the R2 retrotransposon
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DOI：
10.1074/jbc.m310450200
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发表时间：
2004-04-09
影响因子：
4.8
通讯作者：
Eickbush, TH
中科院分区：
文献类型：
--
作者：
Bibillo, A;Eickbush, TH
由非长末端重复逆转录转座子R2编码的逆转录酶已显示能够在两个模板之间不存在预先存在的序列同一性的情况下从一个RNA模板（供体）的5 '末端跳跃到第二个RNA模板（受体）的3'末端。RNA模板之间的这些跳跃与某些RNA病毒编码的RNA指导的RNA聚合酶所描述的端到端模板跳跃具有相似性。在这里，我们第一次描述的机制，这种端到端的模板跳转可以发生。R2逆转录酶的大多数模板跳跃是由酶在cDNA到达供体RNA末端时向cDNA添加非模板化（突出）核苷酸的能力引起的。然后，该酶将这些突出的核苷酸退火至受体RNA的3 '-末端的序列。如果退火涉及受体RNA的末端核苷酸，则退火是最有效的，但可以发生在距离3 '端至少5个核苷酸的位点。这些末端到末端的跳跃类似于非长末端重复反转录转座子整合反应的一部分，可以解释来自多个RNA模板的嵌合整合产物。
The reverse transcriptase encoded by the non-long terminal repeat retrotransposon R2 has been shown to be able to jump from the 5'-end of one RNA template (the donor) to the 3'-end of a second RNA template (the acceptor) in the absence of preexisting sequence identity between the two templates. These jumps between RNA templates have similarity to the end-to-end template jumps described for the RNA-directed RNA polymerases encoded by certain RNA viruses. Here we describe for the first time the mechanism by which such end-to-end template jumps can occur. Most template jumps by the R2 reverse transcriptase are brought about by the enzyme's ability to add nontemplated (overhanging) nucleotides to the cDNA when it reaches the end of the donor RNA. The enzyme then anneals these overhanging nucleotides to sequences at the 3'-end of the acceptor RNA. The annealing is most efficient if it involves the terminal nucleotide(s) of the acceptor RNA but can occur to sites at least 5 nucleotides from the 3'-end. These end-to-end jumps are similar to steps proposed to be part of the integration reaction of non-long terminal repeat retrotransposons and can explain chimeric integration products derived from multiple RNA templates.