Szyszko J, Pietrzykowska I, Twardowski T, Shugar D
Mutat Res. 1983 Mar;108(1-3):13-27. doi: 10.1016/0027-5107(83)90106-9.
Cultivation of E. coli cells in the presence of 5-bromodeoxyuridine (BUdR) leads to formation of lesions in the cellular DNA which affect its secondary structure, as reflected by changes in temperature profiles. Such DNA contains single-stranded regions susceptible to endonuclease S1. One of the major sources of the BU-induced lesions appears to be dehalogenation of incorporated 5-bromouracil (BU) residues, with accompanying formation of uracil. The presence of uracil residues in such DNA was demonstrated directly by chromatography of hydrolyzates, and by the susceptibility of such residues to uracil-DNA glycosylase. The number of uracil residues was dependent on the extent of damage in the DNA, and decreased during the DNA repair that accompanied reactivation of bromouracil-inactivated cells. Dehalogenation of incorporated BU presumably results in formation of apyrimidinic sites by uracil-DNA glycosylase, and then single-strand nicks either by AP-endonuclease and/or dehalogenation. The findings are relevant to the mechanism of BU-induced mutagenesis.
在5-溴脱氧尿苷（BUdR）存在的情况下培养大肠杆菌细胞会导致细胞DNA中形成损伤，这种损伤会影响其二级结构，这在温度曲线的变化中得到体现。这种DNA含有易被核酸酶S1切割的单链区域。BU诱导损伤的主要来源之一似乎是掺入的5-溴尿嘧啶（BU）残基的脱卤作用，并伴随尿嘧啶的形成。通过水解产物的色谱分析以及这些残基对尿嘧啶-DNA糖基化酶的敏感性，直接证明了这种DNA中存在尿嘧啶残基。尿嘧啶残基的数量取决于DNA的损伤程度，并且在伴随溴尿嘧啶灭活细胞重新激活的DNA修复过程中会减少。掺入的BU的脱卤作用可能会导致尿嘧啶-DNA糖基化酶形成无嘧啶位点，然后通过AP内切核酸酶和/或脱卤作用形成单链切口。这些发现与BU诱导的诱变机制相关。
