DNA structure and polymerase fidelity
DNA structure and polymerase fidelity
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DOI：
10.1006/jmbi.1999.3199
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发表时间：
1999-11-05
影响因子：
5.6
通讯作者：
Timsit, Y
中科院分区：
文献类型：
--
作者：
Timsit, Y
DNA复制的准确性来自于DNA聚合酶的固有保真度和DNA序列。虽然最近对聚合酶的结构研究带来了聚合酶保真度的新见解，但DNA序列和结构的作用还不太清楚。在这里，对聚合酶滑移热点的晶体结构的分析，包括（CA）和（A），在不同的分子间环境中的束揭示了，在B型中，这些序列共享共同的结构改变，这可以解释高复制错误率。特别地，在大沟中具有移位碱基对但在小沟中具有表观正常几何形状的双面“Janus样”结构构成了特别适合于误导聚合酶的分子诱饵。大鼠聚合酶β与该结构结合的模型表明，新生模板-引物双链体的构象改变可以通过影响活性位点的几何形状和破坏碱基配对规则来干扰正确的核苷酸掺入，同时逃避错误辨别的酶机制，该错误辨别机制扫描小沟的正确几何形状。通过显示A-型极大地减弱了热点中的序列依赖性结构改变，该研究表明在聚合酶活性位点附近的新生模板-引物双链体的A-构象将有助于保真度。A型可以起到结构缓冲的作用，其保留所有序列的活性位点的正确几何形状。在DNA聚合酶-DNA复合物的可用晶体结构中的新生模板-引物双链体的构象的详细比较表明，聚合酶β，最不精确的酶，在结合B-DNA双链体方面是独特的，甚至接近其活性位点。该模型导致几个预测，讨论了在出版的实验数据的光。(C)北京：科学出版社.
The accuracy of DNA replication results from both the intrinsic DNA polymerase fidelity and the DNA sequence. Although the recent structural studies on polymerases have brought new insights on polymerase fidelity, the role of DNA sequence and structure is less well understood. Here, the analysis of the crystal structures of hotspots for polymerase slippage including (CA), and (A), tracts in different intermolecular con texts reveals that, in the B-form, these sequences share common structural alterations which may explain the high rate of replication errors. In particular, a two-faced "Janus-like" structure with shifted base-pairs in the major groove but an apparent normal geometry in the minor groove constitutes a molecular decoy specifically suitable to mislead the polymerases. A model of the rat polymerase beta bound to this structure suggests that an altered conformation of the nascent template-primer duplex can interfere with correct nucleotide incorporation by affecting the geometry of the active site and breaking the rules of base-pairing, while at the same time escaping enzymatic mechanisms of error discrimination which scan for the correct geometry of the minor groove.In contrast, by showing that the A-form greatly attenuates the sequence-dependent structural alterations in hotspots, this study suggests that the A-conformation of the nascent template-primer duplex at the vicinity of the polymerase active site will contribute to fidelity. The A-form may play the role of a structural buffer which preserves the correct geometry of the active site for all sequences. The detailed comparison of the conformation of the nascent template-primer duplex in the available crystal structures of DNA polymerase-DNA complexes shows that polymerase beta, the least accurate enzyme, is unique in binding to a B-DNA duplex even close to its active site. This model leads to several predictions which are discussed in the light of published experimental data. (C) 1999 Academic Press.