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Optimized End-Stacking Provides Specificity ofN-Methyl Mesoporphyrin IX for Human Telomeric G-Quadruplex DNA
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2012-12-11 , DOI: 10.1021/ja3088746
John M. Nicoludis 1 , Stephen T. Miller 1 , Philip D. Jeffrey 2 , Steven P. Barrett 1 , Paul R. Rablen 1 , Thomas J. Lawton 3 , Liliya A. Yatsunyk 1
Affiliation  

N-methyl mesoporphyrin IX (NMM) is exceptionally selective for G-quadruplexes (GQ) relative to duplex DNA and, as such, has found a wide range of applications in biology and chemistry. In addition, NMM is selective for parallel versus antiparallel GQ folds, as was recently demonstrated in our laboratory. Here, we present the X-ray crystal structure of a complex between NMM and human telomeric DNA dAGGG(TTAGGG)(3), Tel22, determined in two space groups, P2(1)2(1)2 and P6, at 1.65 and 2.15 Å resolution, respectively. The former is the highest resolution structure of the human telomeric GQ DNA reported to date. The biological unit contains a Tel22 dimer of 5'-5' stacked parallel-stranded quadruplexes capped on both ends with NMM, supporting the spectroscopically determined 1:1 stoichiometry. NMM is capable of adjusting its macrocycle geometry to closely match that of the terminal G-tetrad required for efficient π-π stacking. The out-of-plane N-methyl group of NMM fits perfectly into the center of the parallel GQ core where it aligns with potassium ions. In contrast, the interaction of the N-methyl group with duplex DNA or antiparallel GQ would lead to steric clashes that prevent NMM from binding to these structures, thus explaining its unique selectivity. On the basis of the biochemical data, binding of NMM to Tel22 does not rely on relatively nonspecific electrostatic interactions, which characterize most canonical GQ ligands, but rather it is hydrophobic in nature. The structural features observed in the NMM-Tel22 complex described here will serve as guidelines for developing new quadruplex ligands that have excellent affinity and precisely defined selectivity.

中文翻译:

优化的末端堆叠为人端粒 G-四链体 DNA 提供了 N-甲基中卟啉 IX 的特异性

相对于双链 DNA,N-甲基中卟啉 IX (NMM) 对 G-四链体 (GQ) 具有特殊的选择性,因此在生物学和化学中有广泛的应用。此外,正如我们实验室最近证明的那样,NMM 对平行与反平行 GQ 折叠具有选择性。在这里,我们展示了 NMM 和人类端粒 DNA dAGGG(TTAGGG)(3)、Tel22 之间复合物的 X 射线晶体结构,在两个空间群中确定,P2(1)2(1)2 和 P6,在 1.65 和分别为 2.15 Å 分辨率。前者是迄今为止报道的人类端粒 GQ DNA 的最高分辨率结构。生物单元包含一个 5'-5' 堆叠平行四链体的 Tel22 二聚体,两端用 NMM 封顶,支持光谱确定的 1:1 化学计量。NMM 能够调整其大环几何形状,以与有效 π-π 堆叠所需的末端 G-四分体的几何形状紧密匹配。NMM 的平面外 N-甲基基团完全适合平行 GQ 核心的中心,在那里它与钾离子对齐。相比之下,N-甲基与双链 DNA 或反平行 GQ 的相互作用会导致空间冲突,阻止 NMM 与这些结构结合,从而解释了其独特的选择性。根据生化数据,NMM 与 Tel22 的结合不依赖于相对非特异性的静电相互作用,这是大多数典型 GQ 配体的特征,而是本质上是疏水的。
更新日期:2012-12-11
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