STRUCTURE OF DAMAGED DNA

（申请人描述）本研究的长期目标是建立DNA加合物和相关损伤的三维结构，并将选择性损伤DNA的结构特征与其热力学性质和生物过程（包括突变和DNA修复）联系起来。在少数补充的支持下，我们利用高分辨率核磁共振波谱和分子动力学建立了含有外环病变和基本位点的DNA双链的溶液结构，确定了它们的整体结构特征、含病变的碱基比对以及病变部位或附近的扰动。我们未来的研究包括三个领域：(i)新的DNA加合物，（ii） DNA基本位点，（iii）受损的DNA/修复蛋白复合物。我们将对含有损伤的DNA双链进行研究，重点是乙烯、丙烯醛和FaPy-dG，这些加合物是由DNA氧化损伤和脂质过氧化引起的。这些病变的结构与典型的沃森-克里克伙伴和诱变中间体配对将被建立。我们将通过建立糖结构、C1、氢键和基本位点螺旋内或螺旋外位置之间的相关性来扩展我们对基本位点的研究。此外，我们将描述双链基本位点病变，以评估序列背景、错配形成和DNA双链方向性的影响。我们还将确定当MutY与不可切割的DNA底物结合时形成的假定的“翻转”DNA中间体的三维结构，并将建立c端结构域MutY蛋白的溶液结构。

DESCRIPTION: (Applicant's Description) The long-term goal of this research is to establish three-dimensional structures of DNA adducts and related lesions, and to correlate structural features of selectively-damaged DNA with its thermodynamic properties and with biological processes, including mutagenesis and DNA repair. Supported by a minority supplement, we have utilized high-resolution NMR spectroscopy and molecular dynamics to establish solution structures of DNA duplexes containing exocyclic lesions and abasic sites, determining their global structural features, lesion-containing base alignments, and perturbations at or near the lesion site. Our future studies encompass three areas: (i) novel DNA adducts, (ii) DNA abasic sites, and (iii) damaged DNA/repair protein complexes. We will perform studies on lesion-containing DNA duplexes focusing on etheno-, acrolein-, and FaPy-dG, adducts resulting from oxidative DNA damage and lipid peroxidation. The structure of these lesions paired with canonical Watson-Crick partners and mutagenic intermediates will be established. We will extend our studies of abasic sites by establishing correlations between sugar configuration, C1, hydrogen bonding, and the intra- or extrahelical position of the abasic site. In addition, we will characterize bistrand abasic site lesions to evaluate the effects of sequence context, mismatch formation, and directionality in DNA duplexes. We also will determine the three-dimensional structure of a putative "flipped-out" DNA intermediate that forms when MutY binds to a non-cleavable DNA substrate, and will establish a solution structure for the C-terminal domain MutY protein.