Steighner R J, Povirk L F
Department of Pharmacology and Toxicology, Medical College of Virginia, Virginia Commonwealth University, Richmond 23298.
Mutat Res. 1990 Feb;240(2):93-100. doi: 10.1016/0165-1218(90)90012-q.
Previous studies have revealed bleomycin to be a potent base-substitution mutagen in repackaged phage lambda. In order to assess the role of apurinic/apyrimidinic (AP) sites in bleomycin-induced mutagenesis, bleomycin-damaged lambda DNA was treated with putrescine or endonuclease IV to effect cleavage of bleomycin-induced AP sites. The DNA was then packaged, the phage grown in SOS-induced E. coli, and the frequency of clear-plaque mutants in the progeny was determined. Bleomycin-induced mutagenesis was decreased approx. 2-fold by treating the DNA with putrescine, but was unaffected by endonuclease IV. The results are consistent with the production of bleomycin-induced mutation at certain AP sites having a closely opposed single-strand break, since such sites are cleaved by putrescine but not by endonuclease IV.
先前的研究表明，博来霉素在重新包装的λ噬菌体中是一种强效的碱基置换诱变剂。为了评估无嘌呤/无嘧啶（AP）位点在博来霉素诱导的诱变中的作用，用腐胺或核酸内切酶IV处理博来霉素损伤的λDNA，以实现对博来霉素诱导的AP位点的切割。然后对DNA进行包装，在SOS诱导的大肠杆菌中培养噬菌体，并测定子代中清晰噬菌斑突变体的频率。通过用腐胺处理DNA，博来霉素诱导的诱变作用降低了约2倍，但不受核酸内切酶IV的影响。这些结果与在某些具有紧密相对单链断裂的AP位点产生博来霉素诱导的突变一致，因为这些位点可被腐胺切割，但不能被核酸内切酶IV切割。
