Mosevitskaia T V, Pavel'chuk E B, Tomilin N V
Genetika. 1976;12(8):131-8.
Escherichia coli uvrA, polA and uvrD cells carrying non-UV-inducible prophage lambdac1857ind- were infected with 3H-thymidine labelled homoimmune phage lambdac1857, and the effect of UV-irradiation of super-infecting phage and lysogenic bacterial cells on the content of intracellular covalently-closed lambda DNA circles (cccDNA) and pyrimidine dimer content in lambda DNA are studied. UV-irradiation of host cells results in two-fold increase of relative content of cccDNA of UV-irradiated phage lambda in uvrD mutant, while there is no such an effect in uvrA and polA mutants. In UV-irradiated or intact uvrA lysogens cccDNA molecules, forming after the infection with UV-irradiated phage lambda, contain pyrimidine dimers, but in uvrD mutant cccDNA in free of dimers. The data indicate that the repair system induced by UV-irradiation of uvrA and polA cells acts exclusively on the DNA defects appearing after (or in the course) of phage genomes replication. UV-inducible repair system in uvrD mutant can operate also on some intermediates of abortive excision repair, possibly on long single straided excision gaps.
用携带非紫外线诱导型原噬菌体λc1857ind-的大肠杆菌uvrA、polA和uvrD细胞，感染用3H-胸腺嘧啶核苷标记的同源免疫噬菌体λc1857，并研究超感染噬菌体和溶原性细菌细胞的紫外线照射对细胞内共价闭合的λDNA环（cccDNA）含量以及λDNA中嘧啶二聚体含量的影响。宿主细胞的紫外线照射导致uvrD突变体中紫外线照射的噬菌体λ的cccDNA相对含量增加两倍，而uvrA和polA突变体中则没有这种效应。在用紫外线照射的噬菌体λ感染后形成的cccDNA分子中，紫外线照射或完整的uvrA溶原菌含有嘧啶二聚体，但uvrD突变体中的cccDNA不含二聚体。数据表明，uvrA和polA细胞的紫外线照射诱导的修复系统仅作用于噬菌体基因组复制后（或过程中）出现的DNA缺陷。uvrD突变体中的紫外线诱导修复系统也可以作用于流产切除修复的一些中间体，可能作用于长单链切除缺口。
