McCarthy T V, Karran P, Lindahl T
EMBO J. 1984 Mar;3(3):545-50. doi: 10.1002/j.1460-2075.1984.tb01844.x.
The three miscoding alkylated pyrimidines O2-methylcytosine, O2-methylthymine and O4-methylthymine are specifically recognized by Escherichia coli DNA repair enzymes. The activities are induced as part of the adaptive response to alkylating agents. O2-Methylcytosine and O2-methylthymine are removed by a DNA glycosylase, the alkA+ gene product, which also acts on N3-methylated purines. O4-Methylthymine is repaired by a methyltransferase, previously known to correct O6-methylguanine by transfer of the methyl group to one of its own cysteine residues. It is proposed that certain common structural features of the various methylated bases allow each of the two inducible repair enzymes to recognize and remove several different kinds of lesions from alkylated DNA.
三种错编码的烷基化嘧啶——O2-甲基胞嘧啶、O2-甲基胸腺嘧啶和O4-甲基胸腺嘧啶，能够被大肠杆菌DNA修复酶特异性识别。这些活性作为对烷基化剂适应性反应的一部分被诱导产生。O2-甲基胞嘧啶和O2-甲基胸腺嘧啶由一种DNA糖基化酶（alkA+基因产物）去除，该酶也作用于N3-甲基化嘌呤。O4-甲基胸腺嘧啶由一种甲基转移酶修复，该甲基转移酶先前已知通过将甲基转移到其自身的一个半胱氨酸残基上来校正O6-甲基鸟嘌呤。有人提出，各种甲基化碱基的某些共同结构特征使得两种可诱导的修复酶中的每一种都能够识别并从烷基化DNA中去除几种不同类型的损伤。
