Conformation and Multimeric Formation of G-Quadruplexed DNA: Effects of Ligand In

描述（申请人提供）：端粒酶活性与细胞永生和肿瘤发生相关。它负责通过将重复的（TTAGGG）n富含鸟嘌呤的序列添加到3 '-单链端粒突出端来延长染色体DNA。富含鸟嘌呤的序列可以在体外折叠形成G-四链体结构，并且可以抑制端粒酶，为控制肿瘤发生提供了潜在的靶点。然而，稳定四链体结构用于临床应用的四链体相互作用剂（QIA）的开发仍然缓慢，这是因为四链体在溶液中的多态性构象和潜在的四链体多聚化沿着端粒DNA。因此，需要在管理DNA四链体构象和稳定化的基本化学和物理规则的知识的显着增加用于化疗应用的QIA的合理开发。该研究的总体目标集中在生理条件下G-四链体DNA的构象和多聚化。该申请的目的集中于：1）检查不同溶液条件对四链体构象稳定性的影响及其对结合模型QIA配体的调节;和2）检查涉及多聚体四链体形成的构象驱动力和QIA相互作用的影响。我们已经开发了一个新的家庭的荧光标记的人端粒序列（h（TTAGGG）4）通过使用荧光鸟嘌呤类似物（6-MI）的单个鸟嘌呤残基的位点特异性取代。结合CD-测量，电泳和UV的方法进行表征研究，这些荧光端粒序列可以提供光谱信息的独特的鸟嘌呤位点沿着的人四链体序列时，在折叠构象的局部环境影响。所提供的信息将使我们开始了解的作用，构象异质性的个别鸟嘌呤残基在稳定和调节的四链体构象和多聚体形成的解决方案，并使用这些信息的合理设计的QIA具有高的四链体结合的选择性和亲和力。 公共卫生相关性：这项提案的重点是DNA序列，这些DNA序列折叠成四链结构，称为四链体，可以抑制一种与癌症有关的关键蛋白质端粒酶的活性。拟议的研究将提供信息，什么影响的形状和组织的四链体，特别是在解决方案。这些基础知识是至关重要的，因为它将使我们能够更好地设计四链体相互作用剂（QIA）治疗剂，更有效地和选择性地结合，并促进DNA的四链体折叠，以抑制端粒酶和控制肿瘤发生。

DESCRIPTION (provided by applicant): Telomerase activity is linked with cellular immortality and tumorigenesis. It is responsible for the elongation of chromosomal DNA through addition of repetitive (TTAGGG)n guanine-rich sequences to the 3'-single- stranded telomeric overhang. The guanine-rich sequences can fold in vitro to form G-quadruplexes structures, and can inhibit telomerase providing a potential target for controlling tumorigenesis. However, development of quadruplex interactive agents (QIAs) that stabilize the quadruplex structure for clinical application remains slow, because of the polymorphic conformation of quadruplexes in solution and potential quadruplex multimerization along the telomeric DNA. A significant increase in knowledge of the fundamental chemical and physical rules that govern DNA quadruplex conformation and stabilization is thus required for rational development of QIAs for chemotherapeutic applications. The overall goal of the proposed research focuses on conformation and multimerization of G-quadruplexed DNA under physiological conditions. The objectives of the application focus on: 1) examining the effects of varying solution conditions on quadruplex conformational stability and its modulation on binding model QIA ligands; and 2) to examine conformational driving forces involved in multimeric quadruplex formation and the effects of QIA interactions. We have developed a novel family of fluorescently labeled human telomeric sequences (h(TTAGGG)4) through site-specific replacement of single guanine residues using a fluorescent guanine analog (6-MI). In combination with CD-measurements, electrophoretic and UV approaches for characterization studies, these fluorescent telomeric sequences can provide spectroscopic information about local environmental effects at unique guanine sites along the human quadruplex sequence and when in the folded conformation. The information provided will allow us to begin to understand the role of conformational heterogeneity of individual guanine residues in stabilizing and modulating the quadruplex conformation and multimeric formation in solution, and to use this information for rational design of QIAs with high quadruplex binding selectivity and affinity. PUBLIC HEALTH RELEVANCE: The focus of this proposal is on sequences of DNA that fold into a four-stranded structure called a quadruplex and can inhibit the activity of a key protein called telomerase, which is linked with cancer. The proposed studies will provide information on what influences shape and organization of the quadruplex particularly in solution. This basic knowledge is critically important as it will allow us to better design Quadruplex Interactive Agent (QIA) therapeutics that bind more effectively and selectively and promote quadruplex folding of the DNA in order to inhibit telomerase and control tumorigenesis.