DNA polymerase θ (POLQ) can extend from mismatches and from bases opposite a (6-4) photoproduct
DNA polymerase θ (POLQ) can extend from mismatches and from bases opposite a (6-4) photoproduct
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DOI：
10.1016/j.dnarep.2007.08.005
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发表时间：
2008-01-01
期刊：
影响因子：
3.8
通讯作者：
Wood, Richard D.
中科院分区：
文献类型：
--
作者：
Seki, Mineaki;Wood, Richard D.
DNA聚合酶（pol θ）是脊椎动物细胞中由POLQ基因编码的核a家族DNA聚合酶。pol theta和polq缺陷小鼠的生化特性表明，pol theta参与DNA损伤耐受。例如，先前发现pol θ不仅能熟练地结合胸腺嘧啶乙二醇或碱基位点对面的核苷酸，而且还能有效地从病变对面的碱基延伸多核苷酸链。我们进行了实验来确定这种从非标准末端延伸的能力是否是酶的更普遍的特性。Pol theta相对有效地从匹配端以及与A:G， A:T和A:C不匹配的端延伸，比一个经过充分研究的A家族DNA聚合酶，大肠杆菌的无核酸外切酶Pol I具有更少的识别性。虽然pol θ本身不能绕过环丁烷嘧啶二聚体或（6-4）光产物，但它可以从与这些病变隔着的碱基的引物进行一些延伸。当pol θ与DNA聚合酶L（一种可以在紫外线诱导的（6-4）光产物的对面插入碱基的酶）结合时，可以完全绕过（6-4）光产物。这些数据表明，除了能够在某些DNA损伤的反面插入核苷酸外，pol theta还擅长延伸未配对的末端。这些结果表明，在其他DNA聚合酶与核苷酸结合后，pol theta具有作为延伸物的潜力，并有助于理解pol theta在体细胞突变和基因组不稳定中的作用。(C) 2007 Elsevier B.V.版权所有
DNA polymerase theta (pol theta) is a nuclear A-family DNA polymerase encoded by the POLQ gene in vertebrate cells. The biochemical properties of pol theta and of Polq-defective mice have suggested that pol theta participates in DNA damage tolerance. For example, pol theta was previously found to be proficient not only in incorporation of a nucleotide opposite a thymine glycol or an abasic site, but also extends a polynucleotide chain efficiently from the base opposite the lesion. We carried out experiments to determine whether this ability to extend from non-standard termini is a more general property of the enzyme. Pol theta extended relatively efficiently from matched termini as well as termini with A:G, A:T and A:C mismatches, with less descrimination than a well-studied A-family DNA polymerase, exonuclease-free pol I from E. coli. Although pol theta was unable to, by itself, bypass a cyclobutane pyrimidine dimer or a (6-4) photoproduct, it could perform some extension from primers with bases placed across from these lesions. When pol theta was combined with DNA polymerase L, an enzyme that can insert a base opposite a UV-induced (6-4) photoproduct, complete bypass of a (6-4) photoproduct was possible. These data show that in addition to its ability to insert nucleotides opposite some DNA lesions, pol theta is proficient at extension of unpaired termini. These results show the potential of pol theta to act as an extender after incorporation of nucleotides by other DNA polymerases, and aid in understanding the role of pol theta in somatic mutagenesis and genome instability. (C) 2007 Elsevier B.V. All rights reserved.