Coordinating Translesion DNA Synthesis Opposite Damaged DNA

描述（由申请人提供）：生物有机体不断被要求防止和修复对遗传密码的破坏。遗传密码的损伤与细胞功能障碍密切相关，但对内源性和外源性遗传毒性的修饰有几个级别的防御。一旦基因密码发生共价修饰，细胞就会产生一系列修复机制，包括损伤特异性DNA糖基酶、转移酶、核苷酸/碱基切除修复和错配修复途径。如果在复制之前没有将损伤从DNA上移除，那么DNA聚合酶就会受到损伤，而这种损伤在很大程度上决定了这种损伤是否会在遗传密码中产生永久性突变。每个细胞中都有几种类型的聚合酶。一些聚合酶在复制DNA时保持高度的准确性，并且是参与遗传密码复制的主要酶。这些所谓的复制聚合酶通常不太能够绕过受损的DNA，因为催化的每一步都有严格的分子检查点，必须在DNA合成发生之前通过。其他聚合酶具有病变旁路能力，可以在复制叉遇到损伤时帮助它，但这两种一般类型的聚合酶如何协调响应DNA损伤尚不清楚。包括x射线晶体学和氢-氘交换质谱法在内的结构方法将与动力学分析相结合，以确定两种人类y家族DNA聚合酶在受损DNA旁路过程中如何与Werner综合征蛋白相互作用。维尔纳综合征的特点是过早衰老和基因组不稳定，导致肉瘤和间充质肿瘤的发病率异常高。当我们的遗传密码受到破坏时，制造DNA的酶是如何相互作用的，了解这些酶是理解为什么某些化学物质比其他化学物质毒性更大、癌症是如何发展的、甚至与我们为什么衰老有关的重要组成部分。我们的研究计划的目标是试图回答一些重要的问题，这些问题与不同类型的“DNA制造”酶如何一起起作用有关，并更好地定义这些酶的固有功能何时无法克服摆在它们面前的损害。

DESCRIPTION (provided by applicant): Biological organisms are constantly required to prevent and repair damage to the genetic code. Damage to the genetic code is intimately related to cellular dysfunction, but there are several levels of defense against modification by both endogenous and exogenous sources of genotoxicity. Once covalent modification of the genetic code takes place the cell can respond with an arsenal of repair mechanisms including lesion specific DNA glycosylases, transferases, nucleotide/base-excision repair, and mismatch repair pathways. If the lesion is not removed from the DNA prior to replication then enzymes known as DNA polymerases will encounter the damage, and this encounter will, to a large extent, determine whether the damage will yield a permanent mutation in the genetic code. There are several types of polymerase in every cell. Some polymerases maintain a high degree of accuracy when copying DNA and are the main enzymes involved in replication of the genetic code. These so-called replicative polymerases are often less able to bypass damaged DNA because each step in catalysis has stringent molecular checkpoints that must be met before DNA synthesis occurs. Other polymerases possess lesion bypass abilities that can aid the replication fork when it encounters damage, but how these two general types of polymerases are coordinated in response to DNA damage remains unclear. Structural approaches including x-ray crystallograpy and hydrogen-deuterium exchange mass spectrometry will be combined with kinetic analysis in an effort to determine how two human Y-family DNA polymerases interact with the Werner syndrome protein during bypass of damaged DNA. Werner syndrome is characterized by premature aging and genomic instability that leads to unusually high incidence of sarcomas and mesenchymal tumors. Understanding how the enzymes that make our DNA interact when they encounter damage to our genetic code is an important part of understanding why certain chemicals are more toxic than others, how cancer develops, and even relates to why we age? The goals of our research proposal seek to answer some important questions related to how different types of "DNA making" enzymes function together and better define when the inherent functions of these enzymes fail to overcome the damage laid before them. Relevance: The proposal is relevant to our global understanding of genmoic maintenance. Genomic instability a thought to be a central feature of the normal aging process and during tumor development. A more detailed understanding of these processes can lead to better cancer therapeutics and possibly agents that improve the overall well-being of individuals as they age.