Cellular Functions of Eukaryotic DNA Ligases

真核 DNA 连接酶的细胞功能

• 批准号: 6622080
• 负责人: Alan E Tomkinson
• 金额: $ 6.88万
• 依托单位: UNIVERSITY OF TEXAS HLTH SCIENCE CENTER
• 依托单位国家: 美国
• 财政年份: 1993
• 资助国家: 美国
• 起止时间: 1993-08-01 至 2004-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6622080
• 关键词: DNA repair; DNA replication; Saccharomyces cerevisiae; cell cycle; cell growth regulation; enzyme activity; eukaryote; fungal genetics; gene mutation; genetic recombination; genetic strain; genetic transcription; molecular cloning; nucleic acid metabolism; nucleic acid sequence; phenotype; phosphoester ligase

DESCRIPTION (provided by applicant): In multicellular organisms, genomic stability and integrity is maintained by the combined actions of accurate DNA replication machinery and a complex network of DNA repair pathways. DNA joining is an essential step in DNA replication, in DNA excision repair and in the repair of DNA strand breaks. Three mammalian genes encoding DNA ligases, LIG1, LIG3 and LIG4, have been identified. Genetic studies have indicated that the LIG4 gene and the functionally homologous DNL4 gene of Saccharomyces cerevisiae participate in the repair of DNA double-strand breaks (DSB)s by the non-homologous end joining (NHEJ). In mammalian cells, this pathway is required for genomic stability. Furthermore defects in NHEJ result in the type of genetic rearrangements frequently observed in cancer cells. In this proposal we will elucidate the molecular mechanisms of DNA ligase IV-dependent NHEJ in eukaryotes. Preliminary studies have revealed a functional interaction between the complex containing the yeast DNL4 gene product and its partner protein Lif 1, and the multifunctional Rad5O/Mrel l/Xrs complex. In Specific aim 1,we will employ a combination of biochemical and genetic approaches to delineate the molecular mechanisms of NHEJ in yeast. These studies will provide a conceptual framework for Specific aim 2, a parallel investigation of NHEJ in mammalian cells. In the last funding period, we identified a functional interaction between the complex containing the human LIG4 gene product and its partner protein XRCC4 and another critical NHEJ factor, the DNA-dependent protein kinase (DNA-PK). Since yeast cells lack a functional homolog of the kinase subunit of DNA-PK, it appears that there will be important differences between NHEJ in yeast and mammalian cells. The long term goal of our research on eukaryotic DNA ligases is to use these enzymes as molecular probes to gain a better understanding of the complex network of pathways that function to maintain genetic stability. The studies in this proposal will contribute to an overall picture of how the repair of DSBs by NHEJ prevents the deleterious genetic changes associated with cancer cells.

描述（由申请人提供）： 在多细胞生物中，基因组稳定性和完整性由 精确的DNA复制机械和复合物的合并动作 DNA修复途径网络。 DNA连接是DNA的重要步骤 复制，在DNA切除修复和DNA链断裂的修复中。 编码DNA连接酶Lig1，Lig3和Lig4的三个哺乳动物基因已是 确定。遗传研究表明Lig4基因和 酿酒酵母的功能上同源的DNL4基因参与 通过非同源末端连接的DNA双链断裂（DSB）的修复 （nhej）。在哺乳动物细胞中，基因组稳定性需要此途径。 此外，NHEJ的缺陷导致遗传重排类型 在癌细胞中经常观察到。 在此提案中，我们将阐明DNA连接酶的分子机制 IV依赖性NHEJ在真核生物中。初步研究揭示了功能 包含酵母DNL4基因产物的复合物与其之间的相互作用 伴侣蛋白LIF 1和多功能RAD5O/MREL L/XRS复合物。在 特定目标1，我们将采用生化和遗传的组合 描绘酵母中NHEJ的分子机制的方法。这些 研究将为特定目标2提供一个概念框架， NHEJ在哺乳动物细胞中的研究。在最后的资金期间，我们 确定了包含人的复合物之间的功能相互作用 Lig4基因产品及其伴侣蛋白XRCC4和另一个关键NHEJ 因子，DNA依赖性蛋白激酶（DNA-PK）。由于酵母细胞缺乏 DNA-PK的激酶亚基的功能同源物，似乎会有 在酵母菌和哺乳动物细胞中的NHEJ之间是重要的差异。 我们研究真核DNA连接酶的长期目标是使用这些 酶作为分子探针，以更好地了解复合物 能够维持遗传稳定性的途径网络。研究 该提案将有助于总体情况DSB的维修 NHEJ防止了与癌细胞相关的有害遗传变化。