The structures and relative stabilities of d(G x G) reverse Hoogsteen, d(G x T) reverse wobble, and d(G x C) reverse Watson-Crick base-pairs in DNA crystals.
The structures and relative stabilities of d(G x G) reverse Hoogsteen, d(G x T) reverse wobble, and d(G x C) reverse Watson-Crick base-pairs in DNA crystals.
复制标题
DNA 晶体中 d(G x G) 反转 Hoogsteen、d(G x T) 反转摆动和 d(G x C) 反转 Watson-Crick 碱基对的结构和相对稳定性。
DOI：
10.1006/jmbi.1997.1100
复制
发表时间：
1997
影响因子：
5.6
通讯作者：
Ho,PS
中科院分区：
文献类型：
--
作者：
Mooers,BH;Eichman,BF;Ho,PS
我们已经解决了同源双链体d（Gm 5CGCGCG）2和异源双链体d（GCGCGCG）/d（TCGCGCG）和d（GCGCGCG）/d（CCGCGCG）的结构。这些结构形成6个碱基对的相同Z-DNA双链体，在5′端突出单个核苷酸。来自一条链的突出核苷酸保持堆叠并夹在两个相邻Z-DNA双链体的平端之间，而相对链的突出碱基是额外螺旋的。在d（Gm 5CGCGCG）2同源双链体中，相邻双链体的堆叠碱基和螺旋外碱基配对形成d（G · G）反向Hoogsteen碱基对，在d（GCGCGCG）/d（TCGCGCG）和d（GCGCGCG）/ d（CCGCGCG）异源双链体中分别形成d（G · T）反向摆动碱基对和d（G · C）反向Watson-Crick碱基对。有趣的是，在异源双链中仅观察到d（G，T）和d（G · C）碱基对，这表明d（G · T）反向摆动和d（G · C）反向Watson-Crick碱基对在该晶体环境中比d（G · G）反向Hoogsteen碱基对更稳定。为了估计三种类型的反向碱基对的相对稳定性，使用序列的各种混合物生长晶体，并通过质谱分析其链组成。d（G · C）反向Watson-Crick碱基对比d（G·G）反向Hoogsteen碱基对稳定约1.5kcal/mol，d（G · T）反向摆动碱基对比d（G · G）反向Hoogsteen碱基对稳定约0.5kcal/mol。结晶过程中负责区分晶体中的股线的步骤是高度合作的，这表明它发生在晶体生长的初始成核事件期间。
We have solved the structures of the homoduplex d(Gm5CGCGCG)2, and the heteroduplexes d(GCGCGCG)/d(TCGCGCG) and d(GCGCGCG)/d(CCGCGCG). The structures form six base-pairs of identical Z-DNA duplexes with single nucleotides overhanging at the 5′-ends. The overhanging nucleotide from one strand remains stacked and sandwiched between the blunt-ends of two adjacent Z-DNA duplexes, while the overhanging base of the opposing strand is extra-helical. The stacked and the extra-helical bases from adjacent duplexes pair to form a distorted d(G · G) reverse Hoogsteen base-pair in the d(Gm5CGCGCG)2homoduplex, and d(G · T) reverse wobble and d(G · C) reverse Watson-Crick base-pairs in the d(GCGCGCG)/d(TCGCGCG) and d(GCGCGCG)/ d(CCGCGCG) heteroduplexes, respectively. Interestingly, only the d(G,T) and d(G · C) base-pairs were observed in the heteroduplexes, suggesting that both the d(G · T) reverse wobble and d(G · C) reverse Watson-Crick base-pairs are more stable in this crystal environment than the d(G · G) reverse Hoogsteen base-pair. To estimate the relative stability of the three types of reverse base-pairs, crystals were grown using various mixtures of sequences and their strand compositions analyzed by mass spectrometry. The d(G · C) reverse Watson-Crick base-pair was estimated to be more stable by ∼1.5 kcal/mol and the d(G · T) reverse wobble base-pair more stable by ∼0.5 kcal/mol than the d(G · G) reverse Hoogsteen base-pair. The step during crystallization responsible for discriminating between the strands in the crystal is highly cooperative, suggesting that it occurs during the initial nucleating event of crystal growth.