A nuclear 3′-5′ exonuclease proofreads for the exonuclease-deficient DNA polymerase α
A nuclear 3′-5′ exonuclease proofreads for the exonuclease-deficient DNA polymerase α
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DOI：
10.1016/s1568-7864(02)00115-5
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发表时间：
2002-10-01
期刊：
影响因子：
3.8
通讯作者：
Skalski, V
中科院分区：
文献类型：
--
作者：
Brown, KR;Weatherdon, KL;Skalski, V
DNA复制是一种高度精确的过程，旨在在每次细胞分裂期间复制细胞的整个基因组。DNA复制的准确性来源于三个重要组成部分之间的平衡：复制DNA聚合酶(Pols)的碱基选择性、核酸外切校对和复制后错配修复。以前我们发现了一个人类3‘-5’外显子，它的性质表明它可能作为外切酶缺陷的复制型DNA Pola的校对。纯化的外显子没有相关的POL活性，并催化从DNA双链中去除错配的核苷酸。与以前的报道一致，研究发现哺乳动物pola在从错配的DNA末端延伸方面效率低下。然而，在包括外显子的类似反应中，从错配的碱基对开始，POLα催化的延伸增加了4.4-15.7倍。相反，外显子对Klenow(K-)和T7聚合酶外切酶缺陷变体催化错配DNA延伸的能力没有显著影响。分别以24.3×10(-4)和38×10(-4)的频率由polα或K生成的碱基替换催化DNA的连续复制。外显子在与polA的反应中恢复了无错误的DNA复制，而它并没有显著提高K的准确性--这些结果与外显子和olα之间的功能相互作用相一致，以确保准确的DNA复制。0 2002 Elsevier Science B.V.保留所有权利。
DNA replication is a highly accurate process designed to duplicate the entire genome of a cell during each cell division. The accuracy of DNA replication is derived from the balance between three important components: base selectivity by the replicative DNA polymerases (pols), exonucleolytic proofreading, and post-replicative mismatch repair. Previously we identified a human 3'-5' exonuclease (exoN) whose properties suggested it may function as a proofreader for the exonuclease-deficient replicative DNA pol alpha. Purified exoN has no associated pol activity and catalyzes removal of mispaired nucleotides from DNA duplexes. Consistent with previous reports, it was found that mammalian pol alpha is inefficient at extending from mispaired DNA terminals. However, in similar reactions that included exoN, there was a 4.4-15.7-fold increase in pol alpha-catalyzed elongation from mispaired base pairs. In contrast, exoN did not have a dramatic impact on the ability of exonuclease-deficient variants of Klenow (K-) and T7 polymerase to catalyze extension from mispaired DNA. Continuous DNA replication catalyzed by either pol alpha or K- generated base substitutions at a frequency of 24.3 x 10(-4) and 38 x 10(-4), respectively. ExoN restored error-free DNA replication in reactions with pol a whereas it did not significantly improve the accuracy of K- These results are consistent with a functional interaction between exoN and pol alpha to ensure accurate DNA replication. 0 2002 Elsevier Science B.V. All rights reserved.