Electrostatic Binding and Hydrophobic Collapse of Peptide-Nucleic Acid Aggregates Quantified Using Force Spectroscopy
Electrostatic Binding and Hydrophobic Collapse of Peptide-Nucleic Acid Aggregates Quantified Using Force Spectroscopy
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DOI：
10.1021/nn4007237
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发表时间：
2013-06-01
期刊：
影响因子：
17.1
通讯作者：
Ritort, Felix
中科院分区：
文献类型：
--
作者：
Camunas-Soler, Joan;Frutos, Silvia;Ritort, Felix
了解自聚集肽与核酸或其他聚阴离子之间的相互作用机制是理解多种人类疾病（例如，阿尔茨海默氏症和帕金森氏症）。由于疏水自聚集力和静电结合力之间的竞争，确定这种相互作用的亲和力和动力学步骤具有挑战性。Kahalalide F（KF）是一种抗癌疏水肽，含有单个正电荷，可与聚阴离子产生强聚集特性。这使得KF成为一个理想的模型，以阐明自聚集与结合到一个强电荷的生物体，如DNA竞争的机制。我们使用光镊施加机械力到单个DNA分子，并表明KF和DNA相互作用在两步动力学过程中促进的DNA的静电结合到聚集体表面，然后由复合物的稳定，由于疏水相互作用。从测量的拉动曲线，我们确定的结合亲和力，动力学障碍，和长度的DNA片段内的KF-DNA复合物隔离的光谱。我们发现存在一个捕获距离，超过该距离，复合物就会塌陷成由强疏水力稳定的致密聚集体，并讨论了核酸的弯曲刚度如何影响这一过程。我们推测，在体内环境中，KF的静电相互作用增强，由于其聚集可能介导的其他聚阴离子的结合。所提出的方法应该是有用的定量表征其他化合物或蛋白质中的聚集体的形成是相关的。
Knowledge of the mechanisms of interaction between self-aggregating peptides and nucleic adds or other polyanions is key to the understanding of many aggregation processes underlying several human diseases (e.g., Alzheimer's and Parkinson's diseases). Determining the affinity and kinetic steps of such Interactions Is challenging due to the competition between hydrophobic self-aggregating forces and electrostatic binding forces. Kahalalide F (KF) is an anticancer hydrophobic peptide that contains a single positive charge that confers strong aggregative properties with polyanions. This makes KF an ideal model to elucidate the mechanisms by which self-aggregation competes with binding to a strongly charged polyelectrolyte such as DNA. We use optical tweezers to apply mechanical forces to single DNA molecules and show that KF and DNA interact in a two-step kinetic process promoted by the electrostatic binding of DNA to the aggregate surface followed by the stabilization of the complex due to hydrophobic interactions. From the measured pulling curves we determine the spectrum of binding affinities, kinetic barriers, and lengths of DNA segments sequestered within the KF-DNA complex. We find there is a capture distance beyond which the complex collapses into compact aggregates stabilized by strong hydrophobic forces and discuss how the bending rigidity of the nucleic add affects this process. We hypothesize that within an in vivo context, the enhanced electrostatic interaction of KF due to its aggregation might mediate the binding to other polyanions. The proposed methodology should be useful to quantitatively characterize other compounds or proteins in which the formation of aggregates is relevant.