Mouse DNA replicase. DNA polymerase associated with a novel RNA polymerase activity to synthesize initiator RNA of strict size.
Mouse DNA replicase. DNA polymerase associated with a novel RNA polymerase activity to synthesize initiator RNA of strict size.
复制标题
小鼠 DNA 复制酶。
DOI：
10.1016/s0021-9258(18)33941-3
复制
发表时间：
1982
期刊：
影响因子：
--
通讯作者：
T. Seno
中科院分区：
文献类型：
--
作者：
T. Yagura;T. Kozu;T. Seno
一种新的小鼠DNA聚合酶，这里称为“DNA复制酶”，在聚(DT)上从头合成DNA，用于合成RNA，该RNA在随后的DNA合成中起到引子的作用。以前已经报道过(Yagura，T.，Kozu，T.和Seno，T.(1982)J.Biochem)。(Tokyo)91,607-618)，发现了一种新的与DNA复制酶相关的RNA聚合酶活性，它不同于经典的RNA聚合酶。DNA复制酶(甘油梯度沉淀法)合成RNA和DNA被一种特异性刺激因子(MR=13×10(4)，甘油梯度沉淀法)强烈刺激，该刺激因子由两个亚基组成(十二烷基硫酸钠-聚丙烯酰胺凝胶电泳法，MR=63×10(3))。对~(32)P从α标记的核苷三磷酸转移到核糖核酸和脱氧核糖核苷酸的最近邻分析表明，8-10个核苷酸的RNA与DNA产物分子的5‘端是共价连接的。这种RNA被称为启动子RNA，其5‘末端有一个三磷酸基团，其大小和合成几乎不受高浓度脱氧核苷三磷酸的影响，而在这些条件下，脱氧核糖核苷酸被有限地掺入到启动子RNA中。DNA复制酶和刺激因子在单链DNA上协同合成启动子RNA的特性非常重要，因为这些成分似乎参与了启动真核细胞染色体DNA复制中不连续的最早DNA中间体(Okazaki片段)的合成所需的反应。
De novo DNA synthesis on poly(dT) by a novel mouse DNA polymerase, here named "DNA replicase," was examined for the synthesis of RNA which functions as a primer in the subsequent synthesis of DNA. As has been reported previously (Yagura, T., Kozu, T., and Seno, T. (1982) J. Biochem. (Tokyo) 91, 607-618), a novel RNA polymerase activity, which is distinguished from those of classical RNA polymerases, is associated with DNA replicase. The synthesis of RNA and DNA by DNA replicase (Mr = 16 X 10(4), by glycerol gradient sedimentation analysis) was greatly stimulated by a specific stimulating factor (Mr = 13 X 10(4), by glycerol gradient sedimentation analysis) which was found to consist of two subunits (Mr = 63 X 10(3), by sodium dodecyl sulfate-polyacrylamide gel electrophoresis). Nearest neighbor analysis in which transfer of 32P from alpha-labeled nucleoside triphosphates to ribo- and deoxyribonucleotides was examined, showed th at RNA of 8-10 nucleotides long was covalently linked to the 5'-end of the DNA product molecule. This RNA, named initiator RNA, had a triphosphate group at its 5' terminus and its size and synthesis were little affected by the addition of high concentrations of deoxynucleoside triphosphate, while in these conditions deoxyribonucleotides were incorporated into initiator RNA to a limited extent. The characteristics of the DNA replicase and stimulating factor that cooperate to synthesize initiator RNA for subsequent DNA synthesis on single-stranded DNA are important because these components seem to be involved in a reaction required to initiate the synthesis of discontinuous earliest DNA intermediates (Okazaki fragments) in chromosomal DNA replication of eukaryotic cells.