INTERACTIONS AMONG REPLICATION AND MUTATION PROTEINS

环境和内源性因素造成的遗传损伤可导致 出生缺陷、遗传性疾病、癌症， 变老因此，了解突变是如何产生的， 对于理解，也许是防止许多人类 紊乱当受损的DNA不能被修复时， 修复，而是复制。长期目标是 研究是为了了解当DNA复制 复杂的遭遇DNA损伤，并阐明什么细胞 这些因素决定了DNA修复或突变是否占上风。 在大肠杆菌中，DNA损伤诱导大约20种蛋白质， 这就是所谓的SOS响应。该研究计划将 研究DNA复制复合体之间的相互作用 以及RecA、UmuD和UmuC， 通过DNA损伤进行诱变复制这种致突变活性 是由蛋白质-蛋白质相互作用介导的，可能导致 复制复合物的瞬时修饰，DNA聚合酶 III全酶（Pol III HE）。Pol III的校对活动 HE由一个不同的亚基，E1，执行。高细胞水平 抑制SOS诱变，但这种抑制作用可以是 通过UmuDC的同时过量生产缓解。这些和其他 结果表明，SOS蛋白可能与大肠杆菌 这是他们改变Pol III HE的一部分。 具体目标有三个 of this research研究. (i)以确定任何互动之间的电子邮件和 SOS蛋白，并确定任何SOS蛋白的功能意义， 交互;（2）生成和表征 干扰SOS诱变的复制亚基;和（3） 研究SOS蛋白是否与复制亚基相互作用 除此之外，这些研究将阐明 当受损的DNA被复制时发生的相互作用， 可以为发生在更高温度下的类似过程提供模型。 有机体

Genetic damage by environmental and endogenous agents can lead to birth defects, heritable diseases, cancer, and possibly contributes to aging. Thus, understanding how mutations are produced is fundamental to understanding and, perhaps, preventing many human disorders. Mutations are created when damaged DNA fails to be repaired, but, instead, is replicated. The long-term goal of this research is to understand what happens When the DNA replication complex encounters a DNA lesion, and to elucidate what cellular factors determine whether DNA repair or mutation prevails. In Escherichia coli, DNA damage induces about 20 proteins, which together are called the SOS response. The research proposed will investigate the interactions between the DNA replication complex and RecA, UmuD, and UmuC, the SOS proteins that are required for mutagenic replication past DNA lesions. This mutagenic activity is mediated by protein-protein interactions, probably resulting in a transient modification of the replication complex, DNA polymerase III holoenzyme (Pol III HE). The proofreading activity of Pol III HE is performed by a distinct subunit, epsilon. High cellular levels of epsilon inhibit SOS mutagenesis, but this inhibition can be relieved by concurrent overproduction of UmuDC. These and other results suggest that the SOS proteins may interact with epsilon as part of their alteration of Pol III HE. There are three specific aims of this research. (i) to identify any interactions between epsilon and the SOS proteins and to determine the functional significance of any interaction; (2) to generate and characterize new defects in the replication subunits that interfere with SOS mutagenesis; and (3) to investigate if the SOS proteins interact with replication subunits other than epsilon. These studies will elucidate the complex interactions that take place when damaged DNA is replicated and may provide a model for similar processes occurring in higher organisms.