Molecular interactions and regulatory events of telomere proteins

项目总结/摘要 所有的遗传信息都储存在DNA中，DNA被蛋白质复杂地包裹起来形成染色体。 端粒是一种核蛋白复合物，它覆盖并保护染色体末端，防止染色体断裂。 磨损，融合在一起，退化除了覆盖和保护染色体末端， 端粒调节端粒酶的募集，端粒酶是一种合成端粒DNA的特殊酶， 与复制性聚合酶协作并确保完整的染色体复制。在过去的四年里， 在诊断为患有一系列疾病的患者中，已经在端粒末端结合蛋白中发现了多个点突变， 包括许多不同类型的癌症。这些观察结果表明， 端粒蛋白的结构和/或功能导致基因组不稳定性。POT 1（保护端粒） 1)是与人类疾病相关的突变最多的端粒蛋白。POT 1形成异二聚体复合物 与另一种端粒末端结合蛋白TPP 1一起执行不同但同样重要的功能。具体地说， POT 1-TPP 1与端粒的3'末端结合，帮助将端粒酶募集到端粒，并调节端粒的长度。 端粒酶介导的端粒合成。此外，POT 1-TPP 1蛋白保护端粒DNA不被 由DNA损伤机制识别和修复。最后，POT 1-TPP 1异二聚体表现出非凡的 序列特异性，其提供对与RNA或与具有非端粒序列的DNA结合的区分。 本提案的目的是研究POT 1-TPP 1在端粒中的多重和不同的作用 上维护我们将结合联合收割机的结构-功能研究，以确定决定 POT 1-TPP 1功能，我们将证实细胞结果的机制研究。我们将介绍 POT 1和TPP 1的几种疾病相关点突变，并表征蛋白质 结构，以及蛋白质-蛋白质和蛋白质-核酸相互作用。这次调查的结果 揭示致病突变引起的结构和功能改变，并将用于更好地 了解天然异二聚体的各种功能。本研究中的工作将阐明 调节染色体末端保护的基本装配、组织和功能运动。

PROJECT SUMMARY/ABSTRACT All genetic information is stored in DNA that is intricately wrapped by proteins to form chromosomes. Telomeres are the nucleoprotein complexes that cap and protect the ends of chromosomes to prevent them from fraying, fusing together, and degrading. In addition to capping and protecting the ends of chromosomes, telomeres regulate the recruitment of telomerase, a specialized enzyme that synthesizes telomere DNA to collaborate with replicative polymerases and ensure complete chromosome replication. Over the past four years, multiple point-mutations have been identified in telomere end-binding proteins in patients diagnosed with a range of disorders, including many different types of cancer. These observations indicate that subtle changes in the structure and/or function of telomere proteins contributes to genome instability. POT1 (Protection of Telomeres 1) is the most mutated telomere protein associated with human disorders. POT1 forms a heterodimeric complex with another telomere end-binding protein, TPP1, to perform diverse but equally critical functions. Specifically, POT1-TPP1 binds to the extreme 3’ end of telomeres and helps recruit telomerase to the telomere and regulates telomerase-mediated telomere synthesis. In addition, the POT1-TPP1 proteins shield telomere DNA from being recognized and repaired by DNA damage machinery. Finally, the POT1-TPP1 heterodimer exhibits extraordinary sequence specificity that provides discrimination against binding to RNA or to DNA with non-telomere sequence. The objective of the present proposal is to investigate the multiple and diverse roles of POT1-TPP1 in telomere maintenance. We will combine structure-function studies to determine the molecular interactions that dictate POT1-TPP1 functions and we will corroborate the mechanistic studies with cellular outcome. We will introduce several disease-associated point mutations to both POT1 and TPP1 and characterize alterations in protein structure, as well as protein-protein and protein-nucleic acid interactions. The results from this investigation will reveal both structural and functional alterations introduced by pathogenic mutations and will be used to better understand the diverse functions of the native heterodimer. The work performed in this study will shed light on the fundamental assembly, organization, and functional motions that regulate chromosome end protection.