Kunkel T A, Alexander P S, Liu J C, Fox J M
Prog Clin Biol Res. 1986;209A:441-7.
In an attempt to understand the molecular mechanisms of spontaneous and induced mutagenesis in higher organisms, the mutational specificities of highly purified DNA polymerases alpha, beta and gamma have been assessed for a single round on in vitro DNA synthesis with undamaged, biologically active DNA. A forward mutational assay in a nonessential gene has been used, which is capable of detecting frameshift and deletion errors in addition to all twelve possible base substitution errors at 96 different positions in a 250 base target sequence (the lacZ alpha gene in M13mp2 DNA). DNA sequence analyses of over 1000 mutants generated by these enzymes demonstrate the production in vitro of all three classes of errors. The frequencies and specificities of these mutations are highly distinctive for each class of DNA polymerase. These data point to properties of both the DNA and the enzymes themselves which are important in determining the frequency and specificity of spontaneous and perhaps induced mutagenesis.
为了了解高等生物中自发突变和诱导突变的分子机制，已对高度纯化的DNA聚合酶α、β和γ在一轮体外DNA合成过程中的突变特异性进行了评估，所用的是未受损的、具有生物活性的DNA。采用了非必需基因中的正向突变检测法，该方法除了能检测250个碱基靶序列（M13mp2 DNA中的lacZα基因）中96个不同位置的所有十二种可能的碱基替换错误外，还能检测移码和缺失错误。对这些酶产生的1000多个突变体进行的DNA序列分析表明，这三类错误在体外均有产生。这些突变的频率和特异性对于每一类DNA聚合酶来说都具有高度独特性。这些数据表明，DNA和酶本身的特性在决定自发突变以及可能的诱导突变的频率和特异性方面都很重要。
