Modular architecture of the bacteriophage T7 primase couples RNA primer synthesis to DNA synthesis
Modular architecture of the bacteriophage T7 primase couples RNA primer synthesis to DNA synthesis
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DOI：
10.1016/s1097-2765(03)00195-3
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发表时间：
2003-05-01
期刊：
影响因子：
16
通讯作者：
Ellenberger, T
中科院分区：
文献类型：
--
作者：
Kato, M;Ito, T;Ellenberger, T
DNA引物酶可合成能被DNA聚合酶延伸的寡核糖核苷酸引物。细菌的引物酶由锌结合结构域和RNA聚合酶结构域组成，它们在单链DNA的模板序列上聚合核糖核苷酸。我们报道了噬菌体T7引物酶的晶体结构，该结构揭示了它的两个结构域以及结合在活性位点的两个镁离子的存在。核磁共振和生化数据表明，这两个结构域在引物酶与DNA和核苷酸结合之前是分开的。单独的锌结合结构域就能够刺激T7 DNA聚合酶进行引物延伸。这些发现表明，锌结合结构域通过将DNA模板固定在引物酶活性位点，然后将带有引物的DNA模板传递给DNA聚合酶，从而将引物合成与引物利用偶联起来。引物酶的模块式结构以及引发DNA合成的类似机制可能广泛适用于原核生物的引物酶。
DNA primases that synthesize oligoribonucleotide primers that can be extended by DNA polymerase. The bacterial primases consist of zinc binding and RNA polymerase domains that polymerize ribonucleotides at templating sequences of single-stranded DNA. We report a crystal structure of bacteriophage T7 primase that reveals its two domains and the presence of two Mg2+ ions bound to the active site. NMR and biochemical data show that the two domains remain separated until the primase binds to DNA and nucleotide. The zinc binding domain alone can stimulate primer extension by T7 DNA polymerase. These findings suggest that the zinc binding domain couples primer synthesis with primer utilization by securing the DNA template in the primase active site and then delivering the primed DNA template to DNA polymerase. The modular architecture of the primase and a similar mechanism of priming DNA synthesis are likely to apply broadly to prokaryotic primases.