Shedding Light on the Interaction between TMPyP4 and Human Telomeric Quadruplexes
Shedding Light on the Interaction between TMPyP4 and Human Telomeric Quadruplexes
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DOI：
10.1021/jp9066394
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发表时间：
2009-11-05
影响因子：
3.3
通讯作者：
Giancola, Concetta
中科院分区：
文献类型：
--
作者：
Martino, Luigi;Pagano, Bruno;Giancola, Concetta
TMPyP4阳离子卟啉与G-四链结构的结合方式和化学计量性质仍然存在争议，到目前为止还没有一致的模型，特别是对于来自人类端粒序列的分子内G-四链。这些序列在溶液中具有复杂的多态，在分子拥挤条件下似乎减少，其中平行结构似乎是最多的一个。我们用等温滴定量热法和圆二色谱系统地研究了在稀溶液和分子拥挤条件下，TMPyP4与人端粒DNA不同截短形成的4个G-四链体与5‘-或3’-侧翼碱基的结合反应。结果清楚地表明，所有这些G-四链都能够结合多达四个TMPyP4分子。CD研究表明，在稀溶液中，TMPyP4与TMPyP4的相互作用促进杂化结构向AIL反平行构象的转变，而在分子拥挤条件下，相互作用不促进构象变化。ITC在这两种情况下都揭示了结合过程包括两个连续的事件，第一个事件中TMPyP4的一个分子与四链结构相互作用，第二个事件中其他三个分子与结构结合。在分子拥挤条件下，研究了TMPyP4对四链相对于双链DNA的选择性，结果表明TMPyP4比双链结构对四链DNA具有更高的选择性。这一发现加强了TMPyP4的潜在应用。
The nature of the binding mode and stoichiometry of the TMPyP4 cationic porphyrin to G-quadruplex structures continues to be controversial, with no consensus model to date, especially for intramolecular G-quadruplexes from human telomeric sequences. Those sequences possess intricate polymorphism in solution that appears to be reduced under molecular crowding conditions in which the parallel structure appears to be the most populated one. We have performed a systematic Study, in dilute solution and under molecular crowding conditions, of the binding reactions between TMPyP4 and four G-quadruplexes formed by different truncations of human telomeric DNA, with 5'- or 3'-flanking bases, using isothermal titration calorimetry and circular dichroism. The results clearly indicate that all of these G-quadruplexes are able to bind up to four TMPyP4 molecules. CD studies show that interaction with TMPyP4 promotes the conversion of the hybrid structures to ail antiparallel conformation in dilute solution, while under molecular crowding conditions the interaction does not promote any conformational change. ITC reveals in both cases that the binding process comprises two sequential events, a first in which one molecule of TMPyP4 interacts with the quadruplex structures and a second in which three other molecules bind to the structures. The selectivity of TMPyP4 for the quadruplex relative to duplex DNA was also investigated under molecular crowding conditions showing that TMPyP4 has enhanced selectivity for quadruplex DNA compared to the duplex Structure. This finding reinforces the potential applications of TMPyP4.