DNA Polymerases β and λ Bypass Thymine Glycol in Gapped DNA Structures
DNA Polymerases β and λ Bypass Thymine Glycol in Gapped DNA Structures
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DOI：
10.1021/bi901792c
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发表时间：
2010-06-08
期刊：
影响因子：
2.9
通讯作者：
Lavrik, Olga I.
中科院分区：
文献类型：
--
作者：
Belousova, Ekaterina A.;Maga, Giovanni;Lavrik, Olga I.
在这里，我们研究了人类x家族DNA聚合酶β和λ绕过胸腺嘧啶乙二醇（Tg）在缺口DNA底物中的能力，损伤位于模板链的特定位置。测定了最大速度和Michaelis常数值，以研究Mg2+或Mn2+存在下的DNA合成。此外，我们还检测了hRPA（人复制蛋白A）和hPCNA（人增殖细胞核抗原）对DNA聚合酶β和λ的翻译合成活性的影响。结果表明：(i) DNA聚合酶lambda能够催化跨Tg的DNA合成，（ii） DNA聚合酶lambda从碱基对延伸到Tg损伤的能力受到DNA间隙大小的影响，（iii） hPCNA增加了Tg旁路的保真度，并且不影响DNA聚合酶lambda催化的正常DNA合成，（iv） DNA聚合酶β催化Tg相反的所有四种dNTPs的结合。(v)与DNA聚合酶β催化的正常DNA合成相比，hPCNA和hRPA对TLS没有特异性影响。这些结果极大地扩展了我们关于特殊DNA聚合酶处理非常常见的DNA病变（如Tg）的能力的知识。
Here we investigated the ability of the human X-family DNA polymerases beta and lambda to bypass thymine glycol (Tg) in gapped DNA substrates with the damage located in a defined position of the template strand. Maximum velocities and the Michaelis constant values were determined to study DNA synthesis in the presence of either Mg2+ or Mn2+. Additionally, the influence of hRPA (human replication protein A) and hPCNA (human proliferating cell nuclear antigen) on TLS (translesion synthesis) activity of DNA polymerases beta and lambda was examined. The results show that (i) DNA polymerase lambda is able to catalyze DNA synthesis across Tg, (ii) the ability of DNA polymerase lambda to elongate from a base paired to a Tg lesion is influenced by the size of the DNA gap, (iii) hPCNA increases the fidelity of Tg bypass and does not influence normal DNA synthesis catalyzed by DNA polymerase lambda, (iv) DNA polymerase beta catalyzes the incorporation of all four dNTPs opposite Tg, and (v) hPCNA as well as hRPA has no specific effect on TLS in comparison with the normal DNA synthesis catalyzed by DNA polymerase beta. These results considerably extend our knowledge concerning the ability of specialized DNA polymerases to cope with a very common DNA lesion such as Tg.