Lipscomb L A, Peek M E, Morningstar M L, Verghis S M, Miller E M, Rich A, Essigmann J M, Williams L D
School of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta 30332-0400.
Proc Natl Acad Sci U S A. 1995 Jan 31;92(3):719-23. doi: 10.1073/pnas.92.3.719.
We have determined the x-ray structure of a DNA fragment containing 7,8-dihydro-8-oxoguanine (G(O)). The structure of the duplex form of d(CCAGOCGCTGG) has been determined to 1.6-A resolution. The results demonstrate that GO forms Watson-Crick base pairs with the opposite C and that G(O) is in the anti conformation. Structural perturbations induced by C.G(O)anti base pairs are subtle. The structure allows us to identify probable elements by which the DNA repair protein MutM recognizes its substrates. Hydrogen bond donors/acceptors within the major groove are the most likely element. In that groove, the pattern of hydrogen-bond donors/acceptors of C.G(O)anti is unique. Additional structural analysis indicates that conversion of G to G(O) would not significantly influence the glycosidic torsion preference of the nucleoside. There is no steric interaction of the 8-oxygen of G(O) with the phospho-deoxyribose backbone.
我们已经确定了一个含有7,8 - 二氢 - 8 - 氧代鸟嘌呤（G(O)）的DNA片段的X射线结构。已将d(CCAGOCGCTGG)双链体形式的结构解析到1.6埃的分辨率。结果表明，G(O)与对面的C形成沃森 - 克里克碱基对，并且G(O)处于反式构象。由C.G(O)反式碱基对引起的结构扰动很细微。该结构使我们能够确定DNA修复蛋白MutM识别其底物的可能元件。大沟内的氢键供体/受体最有可能是该元件。在该沟中，C.G(O)反式的氢键供体/受体模式是独特的。额外的结构分析表明，G向G(O)的转化不会显著影响核苷的糖苷扭转偏好。G(O)的8 - 氧与磷酸 - 脱氧核糖主链没有空间相互作用。
