DNA/RNA Quadruplexes: Structure, Stability, Interactions

描述（由申请人提供）：本项目主要研究以鸟嘌呤四重构象为基础的四重构象。在过去的五年中，关于这些结构在生物系统中存在及其功能作用的证据越来越多：例如，四重结构已被提出在调节端粒酶活性、转录起始、翻译抑制以及与大量蛋白质特异性结合方面发挥作用。此外，除了抗病毒和抗癌化疗药物外，四联体还被描述为蛋白质识别的折叠基序，以及诊断药物。基于鸟嘌呤四重奏的结构在核酸中是独一无二的，因为它们依赖于某些稳定阳离子的特异性结合。我们的长期目标是加强对这类核酸的热力学、结构和相互作用的理解，特别是在阳离子结合的特定性质方面，折叠RNA四联体的性质及其与DNA四联体的差异，以及它们与其他生物感兴趣的分子的相互作用。特别是，我们建议对一系列具有重要生物学意义的富含鸟嘌呤的序列（包括DNA和RNA形式）进行热力学分析，对这些序列进行结构分析，开发评估四重结构分子结构的方法，并详细研究催化DNA结构及其与血红蛋白的相互作用。实验技术将被用于这一目标包括紫外/CD光谱，等温滴定量热法，核磁共振，荧光和平衡沉淀。这种方法的结合将提供非常重要的核酸物种的构象和相互作用特性的详细检查。

DESCRIPTION (provided by applicant): This project focuses on the unusual nucleic acid conformation of quadruplexes, built upon the guanine quartet. Evidence for the presence of these structures in biological systems, and their functional roles, has been mounting over the past five years: for example, quadruplex structures have been proposed to play a role in regulating telomerase activity, in initiation of transcription, in translational repression, and in binding specifically to a substantial number of proteins. Furthermore, applications have been described for quadruplexes as a folding motif for protein recognition, and as diagnostic agents, in addition to antiviral and anticancer chemotherapeutic agents. Structures based on guanine quartets are unique among nucleic acids in their dependence on specific binding of certain stabilizing cations. Our long term goal is an enhanced understanding of the thermodynamics, structure and interactions of this class of nucleic acids, in particular, in terms of the specific nature of cation binding, the properties of folded RNA quadruplexes and their differences with respect to DNA quadruplexes, and their interactions with other molecules of biological interest. In particular, we propose thermodynamic analyses of a series of biologically significant guanine-rich sequences, both in DNA and RNA forms, structural analyses of these sequences, development of methods to assess the molecularity of quadruplex forms and a detailed investigation of a catalytic DNA construct and its interactions with hemin. Experimental techniques to be employed in this goal include UV/CD spectroscopy, isothermal titration calorimetry, NMR, and fluorescence, and equilibrium sedimentation. This combination of approaches will afford a detailed examination of the conformation and interaction properties of the very important nucleic acid species.