由三链形成的125I标记寡核苷酸诱导的序列特异性DNA双链断裂。

Panyutin I G, Neumann R D

Department of Nuclear Medicine, Clinical Center, National Institutes of Health, Bethesda, MD 20892.

Nucleic Acids Res. 1994 Nov 25;22(23):4979-82. doi: 10.1093/nar/22.23.4979.

A triplex-forming oligonucleotide (TFO) complementary to the polypurine-polypyrimidine region of the nef gene of the Human Immunodeficiency Virus (HIV) was labeled with 125I at the C5 position of a single deoxycytosine residue. Labeled TFO was incubated with a plasmid containing a fragment of the nef gene. Decay of 125I was found to cause double-strand breaks (DSB) within the nef gene upon triplex formation in a sequence specific manner. No DSB were detected after incubation at ionic conditions preventing triplex formation or when TFO was labeled with 32P instead of 125I. Mapping DSB sites with single base resolution showed that they are distributed within 10 bp of a maximum located exactly opposite the position of the [125I] IdC in the TFO. We estimate that on average the amount of DSB produced per decay is close to one.

一种与人类免疫缺陷病毒（HIV）nef基因的聚嘌呤-聚嘧啶区域互补的三链形成寡核苷酸（TFO）在单个脱氧胞嘧啶残基的C5位置用125I进行标记。将标记的TFO与含有nef基因片段的质粒一起孵育。发现125I的衰变在三链形成时以序列特异性方式导致nef基因内的双链断裂（DSB）。在防止三链形成的离子条件下孵育后，或者当TFO用32P而不是125I标记时，未检测到DSB。以单碱基分辨率绘制DSB位点表明，它们分布在TFO中[125I]IdC位置正对面最大位置的10 bp范围内。我们估计，平均每次衰变产生的DSB数量接近一个。