Jarosik G P, Beck D J
Chem Biol Interact. 1984 Sep 15;51(2):247-59. doi: 10.1016/0009-2797(84)90033-4.
Protease deficient recA431 mutants of Escherichia coli are defective in their capacity for induction of SOS responses and were intermediate in their sensitivities to ultraviolet light (UV) and cis-platinum (II) diamminodichloride (cis-PDD). Survival after treatment determined as colony forming ability was greater in rec+ strains and decreased in recA13 mutants which are defective in both recA proteolytic and recombination capabilities. In contrast, recA431 mutants were as sensitive to N-methyl-N'-nitro-N-nitrosoguanidine (NTG) as the recA13 cells. When cells carried either the pKM101 or N3 plasmid, survival after treatment with the three mutagens was increased. Presence of these plasmids in cells also resulted in hypermutagenicity as indicated by reversion of the argE3 mutation using a modified Ames test. Mutagenesis by NTG and cis-PDD was increased, as was survival of cells treated with UV light, cis-PDD and NTG in both recA+ and recA431 (protease deficient) strains. No plasmid mediated enhancement of mutagenesis or cell survival was observed in recA13 mutants. Thus, the ability of the plasmids to enhance cell survival and mutagenesis was dependent on recombination proficiency of the recA gene product and not its regulatory proteolytic activity. Unlike UV or NTG, presence of one of these plasmids was needed to detect reversion of the argE3 mutation by cis-PDD.
大肠杆菌的蛋白酶缺陷型recA431突变体在诱导SOS反应的能力方面存在缺陷，并且对紫外线（UV）和顺式二氯二氨合铂（II）（顺铂）的敏感性处于中等水平。以菌落形成能力确定的处理后存活率在rec⁺菌株中更高，而在recA13突变体中降低，recA13突变体在recA蛋白水解和重组能力方面均有缺陷。相比之下，recA431突变体对N-甲基-N'-硝基-N-亚硝基胍（NTG）的敏感性与recA13细胞相同。当细胞携带pKM101或N3质粒时，用这三种诱变剂处理后的存活率增加。这些质粒在细胞中的存在还导致了超突变性，如使用改良的艾姆斯试验通过argE3突变的回复所表明的那样。NTG和顺铂引起的诱变增加，recA⁺和recA431（蛋白酶缺陷型）菌株中经紫外线、顺铂和NTG处理的细胞存活率也增加。在recA13突变体中未观察到质粒介导的诱变增强或细胞存活增强。因此，质粒增强细胞存活和诱变的能力取决于recA基因产物的重组能力，而不是其调节性蛋白水解活性。与紫外线或NTG不同，需要这些质粒之一的存在才能检测到顺铂引起的argE3突变的回复。
