Huang Haidong, Greenberg Marc M
Department of Chemistry, Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218, USA.
J Org Chem. 2008 Apr 4;73(7):2695-703. doi: 10.1021/jo702614p. Epub 2008 Mar 7.
DNA damage results in the formation of abasic sites from the formal hydrolysis of the glycosidic bond (AP) and several oxidized abasic lesions. Previous studies on AP sites revealed that DNA polymerases preferentially incorporated dA opposite them in approximately 80% of the replication events in Escherichia coli. These results were consistent with the hypothesis that the AP sites are noninstructive lesions due to the absence of a Watson-Crick base whose bypass adheres to the "A-rule." Recent replication studies of the oxidized abasic lesion, 2-deoxyribonolactone (L), revealed that DNA polymerase(s) does not apply the A-rule when bypassing it and incorporates large amounts of dG opposite L. These studies suggested that abasic sites such as L do direct polymerases to selectively incorporate nucleotides opposite them. However, it was not possible to determine the structural basis for this molecular recognition from these experiments. A group of oligonucleotides containing analogues of the AP and L lesions were synthesized and characterized as probes to gain insight into the structural basis for the distinct effect of 2-deoxyribonolactone on replication. These molecules will be useful tools for studying replication in cells and in vitro.
DNA损伤会因糖苷键的形式水解而形成无碱基位点（AP）以及几种氧化的无碱基损伤。先前对AP位点的研究表明，在大肠杆菌中约80%的复制事件中，DNA聚合酶优先在其对面掺入dA。这些结果与以下假设一致：由于缺乏一个其绕过遵循“A规则”的沃森-克里克碱基，AP位点是无指令性损伤。最近对氧化的无碱基损伤2-脱氧核糖内酯（L）的复制研究表明，DNA聚合酶在绕过它时并不应用A规则，而是在L的对面掺入大量的dG。这些研究表明，像L这样的无碱基位点确实会引导聚合酶在其对面选择性地掺入核苷酸。然而，从这些实验中无法确定这种分子识别的结构基础。合成了一组含有AP和L损伤类似物的寡核苷酸，并将其表征为探针，以深入了解2-脱氧核糖内酯对复制产生不同影响的结构基础。这些分子将是研究细胞内和体外复制的有用工具。
