Ganesan A K, Hanawalt P C
Mol Gen Genet. 1985;201(3):387-92. doi: 10.1007/BF00331328.
Derivatives of Escherichia coli K-12 carrying a deletion of the recA gene survive exposure to UV (254 nm) better if they also contain the lexA41 mutation which codes for a labile LexA protein. This effect of the lexA41 mutation is not observed in comparable strains carrying a uvr A6 mutation. Using two independent methods to detect pyrimidine dimers we found that UV irradiated RecA deficient cells removed dimers from their DNA more rapidly if they contained the lexA41 mutation than if they contained the wild-type lexA gene. Our results are consistent with the idea that a relatively high level of UvrABC incision nuclease resulting from inefficient repression of the corresponding genes by the labile LexA41 protein facilitates excision of pyrimidine dimers from the DNA of UV irradiated cells.
携带recA基因缺失的大肠杆菌K-12衍生物，如果还含有编码不稳定LexA蛋白的lexA41突变，那么它们在暴露于紫外线（254纳米）后存活得更好。在携带uvrA6突变的可比菌株中未观察到lexA41突变的这种效应。使用两种独立的方法检测嘧啶二聚体，我们发现紫外线照射的RecA缺陷细胞，如果含有lexA41突变，比含有野生型lexA基因时能更快地从其DNA中去除二聚体。我们的结果与以下观点一致：不稳定的LexA41蛋白对相应基因的抑制效率低下，导致相对高水平的UvrABC内切核酸酶，这有助于从紫外线照射细胞的DNA中切除嘧啶二聚体。
