Moore P D, Rabkin S D, Strauss B S
Basic Life Sci. 1982;20:179-97. doi: 10.1007/978-1-4613-3476-7_11.
We have examined the effect of DNA lesions, which in vivo are potentially mutagenic, on in vitro DNA synthesis carried out by a number of purified DNA polymerases using a 0X174 template. Both acetyl aminofluorene (AAF) adducts and UV-induced pyrimidine dimers are blocks to elongation by DNA polymerases. On UV-irradiated DNA templates synthesis terminates one nucleotide before the sites of pyrimidine dimers with all of the enzymes tested: Pol I and Pol III holoenzyme from Escherichia coli, T4 DNA polymerase, avian myeloblastosis virus reverse transcriptase and a mammalian DNA polymerase alpha. With AAF, which reacts at the C-8 position of guanine, differences are observed between the above enzymes, with the latter two inserting a nucleotide opposite the site of the lesion. Substitution of Mn2+ for Mg2+ as the cation in the Pol I reactions causes changes in the termination pattern on both UV-irradiated and AAF-reacted templates. The significance of these results to the process of inducible error-prone repair and the possible bypass of lesions in the DNA is discussed.
我们已经研究了DNA损伤（在体内可能具有致突变性）对多种纯化的DNA聚合酶利用噬菌体OX174模板进行的体外DNA合成的影响。乙酰氨基芴（AAF）加合物和紫外线诱导的嘧啶二聚体均会阻碍DNA聚合酶的延伸。在紫外线照射的DNA模板上，使用所有测试的酶（来自大肠杆菌的DNA聚合酶I和DNA聚合酶III全酶、T4 DNA聚合酶、禽成髓细胞瘤病毒逆转录酶和哺乳动物DNA聚合酶α）进行合成时，都会在嘧啶二聚体位点前一个核苷酸处终止。对于在鸟嘌呤的C-8位发生反应的AAF，上述酶之间存在差异，后两种酶会在损伤位点对面插入一个核苷酸。在DNA聚合酶I反应中用Mn2+替代Mg2+作为阳离子，会导致在紫外线照射的模板和与AAF反应的模板上终止模式发生变化。本文讨论了这些结果对于诱导性易错修复过程以及DNA损伤可能的跨越的意义。
