Mao H, Reddy G R, Marnett L J, Stone M P
Department of Chemistry, Center in Molecular Toxicology, A. B. Hancock, Jr. Memorial Laboratory for Cancer Research, Vanderbilt University, Nashville, Tennessee 37235, USA.
Biochemistry. 1999 Oct 12;38(41):13491-501. doi: 10.1021/bi9910124.
The refined solution structure for the ring-opened N2-(3-oxo-1-propenyl)-dG derivative of the malondialdehyde deoxyguanosine adduct M(1)G [3-(2'-deoxy-beta-D-erythro-pentofuranosyl)pyrimido[1, 2-a]purin-10(3H)-one] in d(ATCGCXCGGCATG) x d(CATGCCGCGCGAT) [X being N(2)-(3-oxo-1-propenyl)-dG], containing the d(CpG)(3) frameshift hotspot of the Salmonella typhimurium hisD3052 gene, is presented. When inserted into this duplex, M(1)G underwent spontaneous ring opening to N2-(3-oxo-1-propenyl)-dG. NMR analysis revealed that N2-(3-oxo-1-propenyl)-dG induced minor structural perturbations in the hisD3052 oligodeoxynucleotide. However, the stability of the duplex DNA was reduced; the N2-(3-oxo-1-propenyl)-dG-modified hisD3052 oligodeoxynucleotide exhibited a 14 degrees C decrease in T(m) relative to that of the native oligodeoxynucleotide. The modified guanine maintained stacking interactions with neighboring bases but was not Watson-Crick hydrogen bonded. A total of 13 NOEs were observed from the 3-oxo-1-propenyl moiety protons of N2-(3-oxo-1-propenyl)-dG to DNA protons. Molecular dynamics calculations, restrained by 602 distance restraints derived from experimental NOE measurements and 23 empirical distance restraints, converged with pairwise rmsd differences of <0.90 A. The sixth-root residual factor with the NMR data was 9.1 x 10(-2). The cytosine complementary to N2-(3-oxo-1-propenyl)-dG was pushed toward the major groove but maintained partial stacking interactions with its neighboring bases. The modified guanine remained in the anti conformation, while the 3-oxo-1-propenyl moiety was positioned in the minor groove of the duplex. Possible correlations between the relatively small structural perturbations induced in this DNA duplex by N2-(3-oxo-1-propenyl)-dG and the mutagenic spectrum of M(1)G are discussed.
本文给出了鼠伤寒沙门氏菌hisD3052基因d（ATCGCXCGGCATG）×d（CATGCCGCGCGAT）[X为N（2）-（3-氧代-1-丙烯基）-dG]中丙二醛脱氧鸟苷加合物M（1）G [3-（2'-脱氧-β-D-赤藓糖基）嘧啶并[1,2-a]嘌呤-10（3H）-酮]的开环N2-（3-氧代-1-丙烯基）-dG衍生物的精确溶液结构。当插入到该双链体中时，M（1）G自发开环形成N2-（3-氧代-1-丙烯基）-dG。核磁共振分析表明，N2-（3-氧代-1-丙烯基）-dG在hisD3052寡脱氧核苷酸中引起轻微的结构扰动。然而，双链体DNA的稳定性降低；与天然寡脱氧核苷酸相比，N2-（3-氧代-1-丙烯基）-dG修饰的hisD3052寡脱氧核苷酸的熔解温度（Tm）降低了14℃。修饰的鸟嘌呤与相邻碱基保持堆积相互作用，但未形成沃森-克里克氢键。从N2-（3-氧代-1-丙烯基）-dG的3-氧代-1-丙烯基部分质子到DNA质子总共观察到13个核Overhauser效应（NOE）。分子动力学计算受实验NOE测量得到的602个距离约束和23个经验距离约束的限制，收敛时两两均方根偏差小于0.90 Å。与核磁共振数据的六次方根残差因子为9.1×10-2。与N2-（3-氧代-1-丙烯基）-dG互补的胞嘧啶被推向大沟，但与其相邻碱基保持部分堆积相互作用。修饰的鸟嘌呤保持反式构象，而3-氧代-1-丙烯基部分位于双链体的小沟中。讨论了N2-（3-氧代-1-丙烯基）-dG在该DNA双链体中引起的相对较小的结构扰动与M（1）G诱变谱之间可能的相关性。
