Saporito S M, Gedenk M, Cunningham R P
Department of Biological Sciences, State University of New York, Albany 12222.
J Bacteriol. 1989 May;171(5):2542-6. doi: 10.1128/jb.171.5.2542-2546.1989.
The role of exonuclease III and endonuclease IV in the repair of pyrimidine dimers in bacteriophage T4-infected Escherichia coli was examined. UV-irradiated T4 showed reduced survival when plated on an xth nfo double mutant but showed wild-type survival on either single mutant. T4 denV phage were equally sensitive when plated on wild-type E. coli or an xth nfo double mutant, suggesting that these endonucleases function in the same repair pathway as T4 pyrimidine dimer-DNA glycosylase. A uvrA mutant of E. coli in which the repair of pyrimidine dimers was dependent on the T4 denV gene carried on a plasmid was constructed. Neither an xth nor an nfo derivative of this strain was more sensitive than the parental strain to UV irradiation. We were unable to construct a uvrA xth nfo triple mutant. In addition, T4, which turns off the host UvrABC excision nuclease, showed reduced plating efficiency on an xth nfo double mutant.
研究了核酸外切酶III和核酸内切酶IV在噬菌体T4感染的大肠杆菌中嘧啶二聚体修复中的作用。紫外线照射的T4在xth nfo双突变体平板上平板培养时存活率降低,但在任一单突变体上平板培养时显示野生型存活率。T4 denV噬菌体在野生型大肠杆菌或xth nfo双突变体平板上平板培养时同样敏感,表明这些核酸内切酶与T4嘧啶二聚体-DNA糖基化酶在相同的修复途径中起作用。构建了大肠杆菌的uvrA突变体,其中嘧啶二聚体的修复依赖于携带在质粒上的T4 denV基因。该菌株的xth或nfo衍生物对紫外线照射均不比亲本菌株更敏感。我们无法构建uvrA xth nfo三突变体。此外,关闭宿主UvrABC切除核酸酶的T4在xth nfo双突变体上平板培养时平板效率降低。