Kato T, Kondo S
J Bacteriol. 1970 Nov;104(2):871-81. doi: 10.1128/jb.104.2.871-881.1970.
Alleles responsible for X-ray-sensitive characteristics of three mutants of Escherichia coli B, which were also sensitive to ultraviolet (UV) irradiation, were mapped near metE locus, and named res-1, res-2, and res-3. All the res(-) mutants showed no host cell reactivability (Hcr(-)) for transducing deoxyribonucleic acid (DNA) of P1 phage irradiated by UV but they were Hcr(+) for infective DNA of P1 phage. Furthermore, they showed no detectable activity of DNA polymerase. Characteristics of allele res-1 were studied in detail. The mutant res-1 uvr(+) showed an extensive degradation of DNA after UV irradiation. Double mutants carrying res-1 uvrA(-), res-1 uvrB(-), and res-1 uvrC(-) showed no marked increase in UV sensitivity beyond that of the uvr(-) single mutants and only negligible UV-induced DNA degradation. The uvr(-) mutations showed no such suppressive effect on DNA degradation induced by X rays in these double mutants. It is concluded that res(-) mutants are defective in the second step (repair synthesis) of the excision repair process and that DNA polymerase is partly responsible for the assumed resynthesis step.
大肠杆菌B的三个突变体,它们对X射线敏感,同时也对紫外线(UV)照射敏感,负责这些特性的等位基因被定位在metE基因座附近,并分别命名为res - 1、res - 2和res - 3。所有res(-)突变体对经紫外线照射的P1噬菌体转导脱氧核糖核酸(DNA)均无宿主细胞修复活性(Hcr(-)),但对P1噬菌体的感染性DNA则具有Hcr(+)活性。此外,它们未表现出可检测到的DNA聚合酶活性。对res - 1等位基因的特性进行了详细研究。突变体res - 1 uvr(+)在紫外线照射后显示出DNA的广泛降解。携带res - 1 uvrA(-)、res - 1 uvrB(-)和res - 1 uvrC(-)的双突变体在紫外线敏感性方面相较于uvr(-)单突变体并无显著增加,且紫外线诱导的DNA降解可忽略不计。在这些双突变体中,uvr(-)突变对X射线诱导的DNA降解没有这种抑制作用。结论是,res(-)突变体在切除修复过程的第二步(修复合成)中存在缺陷,并且DNA聚合酶部分负责假定的再合成步骤。