Levin H L
Laboratory of Molecular Genetics, National Institute of Child Health and Human Development, Bethesda, Maryland 20892, USA.
Mol Cell Biol. 1995 Jun;15(6):3310-7. doi: 10.1128/MCB.15.6.3310.
Retroviruses and long terminal repeat (LTR)-containing retrotransposons initiate reverse transcription by using a specific tRNA primer than anneals to the primer-binding site of the retroelement transcript. Sequences from a large number of retroviruses and LTR-containing retrotransposons had indicated that the role of tRNAs in priming reverse transcription is universal among these LTR-containing retroelements. Data presented here strongly support the surprising conclusion that Tf1, a highly active LTR-containing retrotransposon isolated from Schizosaccharomyces pombe, undergoes a novel self-priming process that requires hybridization between the primer-binding site and the first 11 bases of the Tf1 transcript. Single-base mutations in these regions block transposition and reverse transcription, while compensatory mutations that reestablish complementarily rescue both defects. In addition, the sequence of the minus-strand RNA primer of reverse transcription was consistent with its being derived from the 5' end of the Tf1 transcript. Evidence that this mechanism defines a new family of retroelements is presented.
逆转录病毒和含长末端重复序列（LTR）的逆转座子通过使用特定的tRNA引物起始逆转录，该引物与逆转元件转录本的引物结合位点退火。来自大量逆转录病毒和含LTR的逆转座子的序列表明，tRNA在引发逆转录中的作用在这些含LTR的逆转元件中是普遍存在的。本文提供的数据有力地支持了这一惊人结论：Tf1是从粟酒裂殖酵母中分离出的一种高度活跃的含LTR的逆转座子，它经历了一个新的自我引发过程，该过程需要引物结合位点与Tf1转录本的前11个碱基之间进行杂交。这些区域的单碱基突变会阻断转座和逆转录，而重新建立互补性的补偿性突变则可挽救这两个缺陷。此外，逆转录负链RNA引物的序列与其来源于Tf1转录本的5'端一致。本文还提供了该机制定义了一个新逆转元件家族的证据。
