Inhibition or Absence of DNA Proofreading Exonuclease is Not Sufficient to Allow Copying of Pyrimidine Dimers
Inhibition or Absence of DNA Proofreading Exonuclease is Not Sufficient to Allow Copying of Pyrimidine Dimers
复制标题
DNA 校对核酸外切酶的抑制或缺失不足以允许嘧啶二聚体的复制
DOI：
--
复制
发表时间：
1981
期刊：
影响因子：
--
通讯作者：
M. Radman
中科院分区：
文献类型：
--
作者：
O. Doubleday;G. Michel;A. Brandenburger;P. Lecomte;M. Radman
关于DNA聚合酶的3‘到5’校对外切酶功能在紫外线诱变过程中的作用的推测，使我们研究了各种不同的DNA聚合酶对完整的和紫外线照射的OX174 DNA进行的DNA合成的程度。在重金属离子Ag+和Hg++存在下，紫外光照射对DNA合成的相对抑制，以及T4嘧啶二聚体特异性内切酶的使用，证实了紫外光对DNA合成的抑制主要是由于模板DNA中存在嘧啶二聚体所致。对缺乏3‘-5’外切酶活性的DNA聚合酶，或具有抑制或变性的3‘-5’外切酶活性的DNA聚合酶的实验表明，无论3‘-5’外切酶的校对活性如何，嘧啶二聚体都构成了DNA合成的绝对障碍。因此，结论是，尽管3‘到5’校对活性的抑制或缺失可能是必需的，但不足以允许有效的反式二聚体合成。
Speculation about the role of the 3′ to 5′ proofreading exonuclease function of DNA polymerases during UV mutagenesis has led us to examine the extents of DNA synthesis performed by a variety of different DNA polymerases, upon intact and UV-irradiated OX174 DNA. The relative inhibition of DNA synthesis after UV-irradiation in the presence of the heavy metal ions Ag+ and Hg++, and use of the T4 pyrimidine dimer specific endonuclease, confirms that the majority of the UV-induced inhibition of DNA synthesis is due to the presence of pyrimidine dimers in the template DNA. Experiments with DNA polymerases lacking 3′ to 5′ exonuclease activity, or with inhibited or denatured 3′ to 5′ exonuclease activity, revealed that pyrimidine dimers constitute an absolute block for DNA synthesis, irrespective of 3′ to 5′ exonuclease proofreading activity. It is therefore concluded that, although it might be required, inhibition or absence of 3′ to 5′ proofreading activity is not sufficient to allow efficient transdimer synthesis.