DNA/RNA Quadruplexes: Structure, Stability, Interactions

描述（由申请人提供）：该项目的重点是不寻常的核酸构象的四链体，建立在鸟嘌呤四联体。在过去的五年里，这些结构在生物系统中的存在及其功能作用的证据越来越多：例如，四链体结构已被提出在调节端粒酶活性、转录起始、翻译抑制和特异性结合大量蛋白质方面发挥作用。此外，已经描述了四链体作为蛋白质识别的折叠基序和作为诊断剂以及抗病毒和抗癌化疗剂的应用。基于鸟嘌呤四联体的结构在核酸中是独特的，因为它们依赖于某些稳定阳离子的特异性结合。我们的长期目标是增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、折叠的RNA四链体的性质及其与DNA四链体的差异以及它们与其他生物学感兴趣的分子的相互作用方面。特别是，我们提出了热力学分析的一系列具有生物学意义的富含鸟嘌呤的序列，无论是在DNA和RNA的形式，这些序列的结构分析，开发的方法来评估四链体形式的分子和催化DNA构建体及其与氯化血红素的相互作用的详细调查。在这一目标中采用的实验技术包括UV/CD光谱，等温滴定量热法，NMR，荧光和平衡沉降。这种方法的组合将提供非常重要的核酸种类的构象和相互作用性质的详细检查。

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.