ENZYMES INVOLVED IN DNA REPAIR AND MEIOSIS

参与 DNA 修复和减数分裂的酶

• 批准号: 3840983
• 负责人: M A RESNICK
• 金额: --
• 依托单位: NATIONAL INSTITUTE OF ENVIRONMENTAL HEALTH SCIENCES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/3840983
• 关键词: DNA repair; Saccharomyces cerevisiae; biological signal transduction; chimeric proteins; enzyme activity; enzyme induction /repression; fungal genetics; fusion gene; gene deletion mutation; gene expression; gene interaction; genetic recombination; genetic strain; guanine nucleotide binding protein; molecular cloning; nuclease; posttranslational modifications; protein sequence; western blottings

From studies of DNA repair and recombination, it is apparent that nucleases play a major role in both of these processes. In the yeast S. cerevisiae the RAD52 gene is essential for the repair of DNA double-strand breaks (DSB), mitotic recombination and for the successful completion of meiosis. Although the function of RAD52 remains unclear, RAD52 may play a role in controlling the levels of a 72 kD nuclease (RhoNUC). From Western blot analysis, the levels of RhoNUC are greatly decreased in rad52 mutants suggesting that this nuclease is under the control of RAD52. The gene encoding RhoNUC (RNC1) has been cloned and sequenced. OFAGE analysis placed the gene encoding RhoNUC on chromosome XI. Examination of the deduced primary sequence reveals that RhoNUC is a chimeric protein with the N-terminal region exhibiting extensive homology with the ras/rho superfamily of GTP binding proteins while the C-terminus appears to encode the nuclease function. Hence, this protein has been named RhoNUC for rho- associated nuclease. Analysis of RNC1::lacZ gene fusions reveals that the control of RhoNUC by RAD52 does not occur at the level of transcription suggesting that the control is at the post-translational level. Although overexpression of RNC1 yields no significant genetic phenotype, the overexpression does cause the cells to enlarge and their nuclei appear enlarged and diffuse. Interestingly, strains carrying deletions for both RAD52 and RNC1 have nearly wild-type levels of direct repeat recombination when measured either on plasmids or on the chromosome (strains carrying only a deletion of RAD52 exhibit recombination levels approximately 100- fold lower than wild-type). From these observations, we believe that RhoNUC represents a newly identified class of proteins exhibiting both a cellular signalling function (G-protein activity) and a DNA metabolic activity (nuclease activity involved in recombination).

从DNA修复和重组的研究中，很明显核酸酶 在这两个过程中发挥重要作用。 在酵母S.酿酒酵母 RAD 52基因是修复DNA双链断裂所必需的 (DSB)、有丝分裂重组和减数分裂的成功完成。 尽管RAD 52的功能尚不清楚，但RAD 52可能在以下方面发挥作用： 控制72 kD核酸酶（RhoNUC）的水平。 Western blot 分析，RhoNUC的水平在rad 52突变体中大大降低 这表明该核酸酶受RAD 52的控制。 基因 编码RhoNUC（RNC 1）的cDNA已被克隆并测序。 OFAGE分析 将编码RhoNUC的基因置于染色体XI上。 审查 推导的一级序列显示RhoNUC是一种嵌合蛋白， 与ras/rho具有广泛同源性的N-末端区域 GTP结合蛋白的超家族，而C-末端似乎编码 核酸酶的功能。 因此，这种蛋白质被命名为RhoNUC， 相关核酸酶 对RNC 1：：lacZ基因融合体的分析表明， RAD 52对RhoNUC的控制并不发生在转录水平 这表明控制在翻译后水平。 虽然 RNC 1的过表达不产生显著的遗传表型， 过度表达确实会导致细胞增大，细胞核出现 扩大和扩散。 有趣的是，携带两种基因缺失的菌株 RAD 52和RNC 1具有接近野生型水平的直接重复重组 当在质粒上或在染色体上测量时（携带 只有RAD 52的缺失表现出约100- 100%的重组水平。 比野生型低1倍）。 根据这些观察，我们认为， RhoNUC代表了一类新鉴定的蛋白质， 细胞信号传导功能（G蛋白活性）和DNA代谢 活性（参与重组的核酸酶活性）。