Conserved sequence box II directs transcription termination and primer formation in mitochondriaw2
Conserved sequence box II directs transcription termination and primer formation in mitochondriaw2
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DOI：
10.1074/jbc.m602429200
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发表时间：
2006-08-25
影响因子：
4.8
通讯作者：
Falkenberg, Maria
中科院分区：
文献类型：
--
作者：
Pham, Xuan Hoi;Farge, Geraldine;Falkenberg, Maria
人线粒体转录机制产生启动重链DNA合成所需的RNA引物。来自重链起点的大多数DNA复制事件过早终止，形成持久的RNA-DNA杂合体，其保持与亲本DNA链退火。这种三链结构被称为D环，包含保守的序列盒II，这是正确引物形成所需的DNA元件。我们在这里使用一个纯化的重组线粒体转录系统，并证明保守序列盒II是一个序列依赖的转录终止元件在体外。来自轻链启动子的转录在线粒体基因组中的位置300-282处过早终止，这与人线粒体D环中的主要RNA-DNA转换点一致。基于我们的研究结果，我们提出了一个模型的引物形成在重链DNA复制的起点。
The human mitochondrial transcription machinery generates the RNA primers needed for initiation of heavy strand DNA synthesis. Most DNA replication events from the heavy strand origin are prematurely terminated, forming a persistent RNA-DNA hybrid, which remains annealed to the parental DNA strand. This triple-stranded structure is called the D-loop and encompasses the conserved sequence box II, a DNA element required for proper primer formation. We here use a purified recombinant mitochondrial transcription system and demonstrate that conserved sequence box II is a sequence-dependent transcription termination element in vitro. Transcription from the light strand promoter is prematurely terminated at positions 300-282 in the mitochondrial genome, which coincide with the major RNA-DNA transition points in the D-loop of human mitochondria. Based on our findings, we propose a model for primer formation at the origin of heavy strand DNA replication.