Dodson L A, Hadden C T
J Bacteriol. 1980 Nov;144(2):840-3. doi: 10.1128/jb.144.2.840-843.1980.
The fate of pyrimidine dimers in deoxyribonucleic acid (DNA) newly synthesized by Bacillus subtilis after ultraviolet irradiation was monitored by use of a damage-specific endonuclease that introduces single-strand breaks adjacent to nearly all of the dimer sites. Two Uvr- strains, one defective in the initiation of dimer excision and the other defective in a function required for efficient dimer excision, were found to be similar to their wild-type parent in the kinetics and extent of converting low-molecular-weight DNA newly synthesized after ultraviolet irradiation to high molecular weight. In the Uvr- strains large molecules of newly synthesized DNA remained susceptible to nicking by the damage-specific endonuclease even after extended incubation in growth medium, whereas the enzyme-sensitive sites were rapidly removed from both preexisting and newly synthesized DNA in Uvr+ cells. Our results support the hypothesis that postreplication repair in bacteria includes recombination between dimer-containing parental DNA strands and newly synthesized strands.
利用一种损伤特异性核酸内切酶监测紫外线照射后枯草芽孢杆菌新合成的脱氧核糖核酸（DNA）中嘧啶二聚体的命运，该酶在几乎所有二聚体位点相邻处引入单链断裂。发现两个Uvr-菌株，一个在二聚体切除起始方面有缺陷，另一个在有效二聚体切除所需的功能方面有缺陷，它们在将紫外线照射后新合成的低分子量DNA转化为高分子量的动力学和程度上与它们的野生型亲本相似。在Uvr-菌株中，即使在生长培养基中长时间孵育后，新合成的DNA大分子仍易被损伤特异性核酸内切酶切割，而在Uvr+细胞中，酶敏感位点会从既存的和新合成的DNA中迅速去除。我们的结果支持这样一种假说，即细菌中的复制后修复包括含二聚体的亲本DNA链与新合成链之间的重组。
