Single Stranded DNA Recognition in Telomeres

描述（由申请人提供）：端粒是真核生物染色体末端的核蛋白结构，由一套高度特化的蛋白质维持和保护。这些蛋白质负责染色体维护，并在癌症和衰老中发挥重要作用。端粒的关键活性是保守的富含GT的单链突出端的适当加帽和加工。失去区分这种天然末端与受损DNA的能力是灾难性的，导致严重的基因组不稳定性。复制酶端粒酶对突出端的访问受到严格控制，因为这种活性调节细胞的增殖潜力。癌细胞的关键特征之一是它们无限的增殖潜力，这反过来又依赖于端粒的维持和长度调节。端粒酶在大约85%的肿瘤细胞中被激活，但在邻近的非肿瘤细胞中不被激活。然而，过早的端粒缩短也会导致各种严重的疾病状态。我们工作的目标是了解端粒末端的蛋白质和DNA结构的调节和控制如何介导这些基本活动。我们的项目集中在模式生物芽殖酵母和高等真核生物中端粒单链突出端的关键蛋白质的结构和活性。在芽殖酵母中，必需蛋白Cdc13结合单链突出端，保护染色体末端不被降解，并调节端粒酶的活性。这些活动中的每一个对于维持端粒的完整性和功能都是至关重要的。从Cdc 13的研究中获得的知识将加速我们理解人类和其他高等真核生物端粒维持的能力。该项目将扩展我们的知识Cdc13功能，通过检查参与Cdc13与端粒DNA的相互作用的分子识别的元素，使用生物化学，生物物理学和结构的方法。此外，该项目还将研究Cdc 13内一个重要调控结构域的结构和生化属性，该结构域在端粒长度调控中起着至关重要的作用。最后，该项目将研究高等真核生物中的端粒结构，其中最近发现的Pot1蛋白结合单链突出端并执行末端保护和端粒酶募集活动。这项工作将有助于在分子水平上理解端粒末端保护和长度调节，并将提供帮助设计癌症和衰老新疗法所需的结构和功能知识。

DESCRIPTION (provided by applicant): Telomeres, the nucleoprotein structures at the ends of eukaryotic chromosomes, are maintained and protected by a suite of highly specialized proteins. These proteins are responsible for chromosome maintenance and play important roles in cancer and aging. A critical activity at telomeres is the proper capping and processing of a conserved GT-rich single-stranded overhang. Loss of the ability to discriminate this natural end from damaged DNA is catastrophic, leading to severe genomic instability. Access of the replicative enzyme telomerase to the overhang is tightly controlled, as this activity regulates the proliferative potential of the cell. One of the key hallmarks of cancer cells is their unlimited proliferative potential, which is, in turn, dependent on telomere maintenance and length regulation. Telomerase is activated in approximately 85% of tumor cells, but not in neighboring non-tumorous cells. However, premature telomere shortening can also lead to a variety of serious disease states. The goal of our work is to understand how modulation and control of the protein and DNA structure at the end of the telomeres mediates these essential activities. Our project focuses on the structures and activities of key proteins found at the telomeric single stranded overhang in the model organism budding yeast and in higher eukaryotes. In the budding yeast, the essential protein Cdc13 binds the single stranded overhang, protects the ends of chromosomes from degradation, and regulates the activity of telomerase. Each of these activities is critical for maintaining telomere integrity and function. The knowledge gained from the study of Cdc 13 will accelerate our ability to understand telomere maintenance in humans and other higher eukaryotes. This project will extend our knowledge of Cdc13 function, by examining the elements of molecular recognition involved in the interaction of Cdc13 with telomeric DNA using biochemical, biophysical, and structural methods. In addition, this project will investigate the structural and biochemical attributes of an important regulatory domain within Cdc 13 that plays a crucial role in telomere length regulation. Finally, this project will examine telomere structure in higher eukaryotes, where the recently discovered Pot1 proteins bind the single-stranded overhang and perform end protection and telomerase recruitment activities. This work will contribute to a molecular level understanding of telomere end protection and length regulation, and will provide the structural and functional knowledge needed to help design new therapeutics for cancer and aging.