DNA binding properties of human DNA polymerase η:: implications for fidelity and polymerase switching of translesion synthesis
DNA binding properties of human DNA polymerase η:: implications for fidelity and polymerase switching of translesion synthesis
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DOI：
10.1111/j.1365-2443.2004.00797.x
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发表时间：
2004-12-01
期刊：
影响因子：
2.1
通讯作者：
Hanaoka, F
中科院分区：
文献类型：
--
作者：
Kusumoto, R;Masutani, C;Hanaoka, F
人XPV（着色性干皮病变体）基因负责癌症易感性着色性干皮病综合征，并编码DNA聚合酶eta（pol eta），其催化顺式-顺式环丁烷胸腺嘧啶二聚体（TT二聚体）和其他损伤的有效跨损伤合成。聚合酶在未受损模板上的DNA合成保真度极低，这表明聚合酶活性必须限制在DNA上受损的位点。然而，人们对pol eta的活性如何靶向并限制在受损的DNA上知之甚少。在这里，我们表明，无论TT二聚体的存在下，聚合酶结合模板/引物DNA。相反，只有当引物的3 '端是位于病变对面的腺苷残基时，才观察到与含有TT二聚体的模板/引物DNA的结合增强。当两个核苷酸已经掺入引物中超过TT二聚体位置时，聚合物-模板/引物DNA复合物被去稳定化，允许通过DNA聚合酶α或δ恢复DNA合成。我们的研究为TT二聚体位点的聚合酶转换提供了机制解释。
The human XPV (xeroderma pigmentosum variant) gene is responsible for the cancer-prone xeroderma pigmentosum syndrome and encodes DNA polymerase eta (pol eta), which catalyses efficient translesion synthesis past cis-syn cyclobutane thymine dimers (TT dimers) and other lesions. The fidelity of DNA synthesis by pol eta on undamaged templates is extremely low, suggesting that pol eta activity must be restricted to damaged sites on DNA. Little is known, however, about how the activity of pol eta is targeted and restricted to damaged DNA. Here we show that pol eta binds template/primer DNAs regardless of the presence of TT dimers. Rather, enhanced binding to template/primer DNAs containing TT dimers is only observed when the 3'-end of the primer is an adenosine residue situated opposite the lesion. When two nucleotides have been incorporated into the primer beyond the TT dimer position, the pol eta-template/primer DNA complex is destabilized, allowing DNA synthesis by DNA polymerases alpha or delta to resume. Our study provides mechanistic explanations for polymerase switching at TT dimer sites.