Burns P A, Gordon A J, Glickman B W
Department of Biology, York University, Toronto, Ontario, Canada.
Carcinogenesis. 1988 Sep;9(9):1607-10. doi: 10.1093/carcin/9.9.1607.
The mutational specificity of the carcinogenic alkylating agent N-methyl-N-nitrosourea (MNU) was investigated through the DNA sequence characterisation of 104 lacI-d mutations induced by this agent in the lacI gene of Escherichia coli. The vast majority (95%) of MNU-induced mutations were G:C----A:T transitions. An analysis of neighbouring base sequence revealed that this transition was almost 10 times more likely to occur if the mutated guanine residue was preceded (5') by a purine (R) rather than a pyrimidine (Y); apart from this 5'-R-G-3' influence no other site specificity of mutation was observed. This 5'-flanking base influence on mutability has also been observed in this system with other mechanistically similar alkylating agents.
通过对致癌烷化剂N-甲基-N-亚硝基脲（MNU）在大肠杆菌lacI基因中诱导产生的104个lacI-d突变进行DNA序列分析，研究了该试剂的突变特异性。MNU诱导的绝大多数（95%）突变是G:C向A:T的转换。对相邻碱基序列的分析表明，如果突变的鸟嘌呤残基在5'端之前是嘌呤（R）而不是嘧啶（Y），那么这种转换发生的可能性几乎要高10倍；除了这种5'-R-G-3'的影响外，未观察到其他突变位点特异性。在该系统中，使用其他机制相似的烷化剂时，也观察到了这种5'侧翼碱基对突变性的影响。
