The role of Orc6 in DNA replication and cytokinesis

抽象的。 起源识别复合物（ORC），异聚六亚基蛋白 复杂，是DNA复制所必需的。ORC的功能也超越了DNA 复制的我们发现最小的ORC亚基，Orc6蛋白，对于 DNA结合和复制，并与转录因子具有结构同源性 TFIIB表明它可能靶向复制前复合物的形成， DNA复制的起源此外，我们确定了保守的基序在C- Orc6的末端，其负责与核心ORC复合物的相互作用。 该基序中的突变影响六亚基ORC的完整性，该六亚基ORC有助于细胞的增殖。 Meier-Gorlin综合征（MGS）的发病机制。Orc6也有一个功能， 胞质分裂它通过其Pnut亚基直接与septin复合物结合，刺激 果蝇septin复合物的内在GT3活性，并大大促进septin 丝形成我们提案的总体目标是， Orc6在DNA复制和胞质分裂中的功能 系统我们的实验旨在回答关于 Orc6的结构，其在复制中的功能及其在Septin聚合中的作用。 果蝇模型系统将用于分析自然发生的 以及在不同蛋白质功能中的人Orc6的结构引导的靶向突变。 因为ORC在进化中是保守的，我们对它的功能的了解， 果蝇的研究对于我们了解ORC在其他神经系统中的功能具有重要意义。 真核生物更好地了解ORC在果蝇中的功能将为我们提供 深入了解ORC在哺乳动物中的行为，并提供线索， 失调会导致癌症

Abstract. The Origin Recognition Complex (ORC), heteromeric six-subunit protein complex, is essential for DNA replication. ORC's functions also extend beyond DNA replication. We found that the smallest of ORC subunit, Orc6 protein, is important for DNA binding and replication and has a structural homology with transcription factor TFIIB suggesting that it may target the formation of pre-replicative complex to the origins of DNA replication. Furthermore, we identified conserved motif within the C- terminus of Orc6 which is responsible for its interaction with the core ORC complex. Mutations in this motif affect the integrity of six-subunit ORC contributing to the pathogenesis of Meier-Gorlin syndrome (MGS) in humans. Orc6 also has a function in cytokinesis. It binds directly to septin complex via its Pnut subunit, stimulates the intrinsic GTPase activity of the Drosophila septin complex and greatly facilitates septin filament formation. The overall goal of our proposal is to characterize the mechanism of Orc6 functions in DNA replication and cytokinesis using Drosophila as a model system. Our experiments are designed to answer important questions about the structure of Orc6, its functions in replication and its role in septin polymerization. Drosophila model systems will be used to analyze the effects of naturally occurring and structure-guided targeted mutations of human Orc6 in diverse protein functions. Because ORC is conserved in evolution, what we learn about its functions in Drosophila will be valuable to our understanding of ORC's functions in other eukaryotes. A better understanding of how ORC functions in Drosophila will provide insights into ORC's behavior in mammals and provide clues as to how its misregulation leads to cancer.