Biochemical properties of Saccharomyces cerevisiae DNA polymerase IV
Biochemical properties of Saccharomyces cerevisiae DNA polymerase IV
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DOI：
10.1074/jbc.m501981200
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发表时间：
2005-05-20
影响因子：
4.8
通讯作者：
Kunkel, TA
中科院分区：
文献类型：
--
作者：
Bebenek, K;Garcia-Diaz, M;Kunkel, TA
虽然哺乳动物编码多种涉及DNA修复的X家族DNA聚合酶，但酿酒酵母只有一种DNA聚合酶IV（pol IV）。为了更好地了解pol IV的修复功能，在这里我们描述了其生化特性。与哺乳动物pol β和pol λ相似，但与pol μ不同，pol IV具有内在的5 ′-2-脱氧核糖-5-磷酸裂解酶活性。Pol IV的持续合成能力较低，可以填补DNA中的短缺口。与pol β和pol λ的情况不同，pol IV的间隙填充活性不被下游引物上的5 ′-磷酸增强，而是被5 ′-末端合成脱碱基位点刺激。Pol IV以相对于dNTPs异常高的效率将rNTPs掺入DNA中，这是与pol beta而不是pol mu或pol lambda共有的性质。最后，pol IV是高度不准确的，具有不寻常的错误特异性，表明能够以有限的同源性延伸引物末端。这些特性与pol IV在碱基切除修复中的可能作用一致，并且与其在双链断裂的非同源末端连接中的已知作用一致，可能包括具有受损末端的那些。
Although mammals encode multiple family X DNA polymerases implicated in DNA repair, Saccharomyces cerevisiae has only one, DNA polymerase IV ( pol IV). To better understand the repair functions of pol IV, here we characterize its biochemical properties. Like mammalian pol beta and pol lambda, but not pol mu, pol IV has intrinsic 5'-2-deoxyribose-5-phosphate lyase activity. Pol IV has low processivity and can fill short gaps in DNA. Unlike the case with pol beta and pol lambda, the gap-filling activity of pol IV is not enhanced by a 5'-phosphate on the downstream primer but is stimulated by a 5'-terminal synthetic abasic site. Pol IV incorporates rNTPs into DNA with an unusually high efficiency relative to dNTPs, a property in common with pol beta but not pol mu or pol lambda. Finally, pol IV is highly inaccurate, with an unusual error specificity indicating the ability to extend primer termini with limited homology. These properties are consistent with a possible role for pol IV in base excision repair and with its known role in non-homologous end joining of double strand breaks, perhaps including those with damaged ends.