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首页> 外文期刊>Molecular and Cellular Biology >UV light-induced cyclobutane pyrimidine dimers are mutagenic in mammalian cells.
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UV light-induced cyclobutane pyrimidine dimers are mutagenic in mammalian cells.

机译：UV光诱导的环丁烷嘧啶二聚体在哺乳动物细胞中致致诱变。

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We used a simian virus 40-based shuttle vector plasmid, pZ189, to determine the role of pyrimidine cyclobutane dimers in UV light-induced mutagenesis in monkey cells. The vector DNA was UV irradiated and then introduced into monkey cells by transfection. After replication, vector DNA was recovered from the cells and tested for mutations in its supF suppressor tRNA marker gene by transformation of Escherichia coli carrying a nonsense mutation in the beta-galactosidase gene. When the irradiated vector was treated with E. coli photolyase prior to transfection, pyrimidine cyclobutane dimers were removed selectively. Removal of approximately 90% of the pyrimidine cyclobutane dimers increased the biological activity of the vector by 75% and reduced its mutation frequency by 80%. Sequence analysis of 72 mutants recovered indicated that there were significantly fewer tandem double-base changes and G X C----A X T transitions (particularly at CC sites) after photoreactivation of the DNA. UV-induced photoproducts remained (although at greatly reduced levels) at all pyr-pyr sites after photoreactivation, but there was a relative increase in photoproducts at CC and TC sites and a relative decrease at TT and CT sites, presumably due to a persistence of (6-4) photoproducts at some CC and TC sites. These observations are consistent with the fact that mutations were found after photoreactivation at many sites at which only cyclobutane dimers would be expected to occur. From these results we conclude that UV-induced pyrimidine cyclobutane dimers are mutagenic in DNA replicated in monkey cells.
机译：我们使用了一种基于Simian病毒40型梭子丝体，PZ189，确定嘧啶环丁烷二聚体在猴细胞中嘧啶型诱变中的作用。紫外线辐照载体DNA，然后通过转染引入猴细胞中。复制后，通过细胞中回收载体DNA，并通过在β-半乳糖苷酶基因中携带非义突变的大肠杆菌转化来测试其Supf抑制器TRNA标志物基因的突变。当在转染之前用大肠杆菌光解酶处理辐照的载体时，选择性地除去嘧啶环丁烷二聚体。除去约90％的嘧啶环丁烷二聚体将载体的生物活性增加75％并将其突变频率降低80％。回收的72个突变体的序列分析表明，在DNA的光敏发生后，串联双基变化和G X C - --- X T过渡（特别是在CC位点）。在光反变后所有的Pyr-Pyr位点在所有Pyr-Pyr位点处保持紫外线诱导的光调节（尽管在大大降低的水平）中，但CC和TC位点的光调节相对增加，并且TT和CT位点的相对降低，可能是由于持续存在（6-4）一些CC和TC位点的光调节。这些观察结果是一致的，即在许多位点在预期发生环丁烷二聚体的许多位点发生突变之后发现突变。从这些结果来，我们得出结论，紫外诱导的嘧啶环丁烷二聚体在猴细胞复制的DNA中是致突变的。

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