Anderson R D, Veigl M L, Baxter J, Sedwick W D
Ireland Cancer Center Research Laboratories/Case Western Reserve University, Cleveland, OH 44106.
Mutat Res. 1993 Oct;294(3):215-22. doi: 10.1016/0921-8777(93)90004-z.
LacI mutations induced by doxorubicin in a wild-type, uvr(A)BC repair-proficient E. coli strain were analyzed by DNA sequencing. These mutations were contrasted with mutations previously recovered from doxorubicin-treated uvrB- organisms in order to assess the role of excision repair in doxorubicin-induced genotoxicity. After a 30-min exposure of wild-type E. coli to 330 microM doxorubicin, survival was 34% and the overall lacI mutation frequency increased 1.8-fold to 340 x 10(-8). The distribution of doxorubicin-induced mutants among subclasses of mutation involving the i-d and lac operator regions differed significantly between repair-proficient and -deficient strains. Distributional differences appeared to result both from a decrease in deletions involving the lac operator and an increase in base substitutions involving the i-d region in repair proficient organisms. However, elements of the doxorubicin-induced mutation spectrum in uvrB- E. coli are still discernable in wild-type organisms. These elements include the remarkable shift of 3'-deletion endpoints to palindromic sequence within the lac operator and the recovery of multiple isolates of T:A-->A:T transversions at position 96 in doxorubicin-treated cultures. These observations suggest that components of the uvr(A)BC nucleotide excision repair system function through a general mechanism prior to fixation of mutations to reduce, but not completely eliminate, the genotoxic effects of doxorubicin.
通过DNA测序分析了阿霉素在野生型、uvr(A)BC修复功能正常的大肠杆菌菌株中诱导产生的LacI突变。将这些突变与先前从经阿霉素处理的uvrB缺陷型菌株中获得的突变进行对比，以评估切除修复在阿霉素诱导的遗传毒性中的作用。野生型大肠杆菌在330 microM阿霉素中暴露30分钟后，存活率为34%，总体LacI突变频率增加了1.8倍，达到340×10(-8)。在涉及i-d和lac操纵子区域的突变亚类中，阿霉素诱导的突变体分布在修复功能正常和缺陷的菌株之间存在显著差异。分布差异似乎是由于修复功能正常的生物体中涉及lac操纵子的缺失减少以及涉及i-d区域的碱基替换增加所致。然而，uvrB缺陷型大肠杆菌中阿霉素诱导的突变谱元素在野生型生物体中仍然可以辨别。这些元素包括3'-缺失终点显著转移到lac操纵子内的回文序列，以及在经阿霉素处理的培养物中96位的多个T:A→A:T颠换分离株的出现。这些观察结果表明，uvr(A)BC核苷酸切除修复系统的组件在突变固定之前通过一种通用机制发挥作用，以减少但不能完全消除阿霉素的遗传毒性作用。
