Mechanisms of Genomic Rearrangement in Yeast

酵母基因组重排机制

• 批准号: 8919182
• 负责人: Lorraine Symington
• 金额: $ 40.5万
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1990
• 资助国家: 美国
• 起止时间: 1990-05-01 至 1993-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8919182&HistoricalAwards=false
• 关键词: Mechanisms; Genomic; Rearrangement; Yeast

We have isolated a hyper-recombination mutants, TOP3 that identifies a novel eukaryotic topoisomerase in the yeast, Saccharomyces cerevisiae. The predicted open reading frame of the TOP3 gene is homologous to the bacterial type, I topoisomerase, TopA, but not homologous to eukaryotic type I or II enzymes. We plan to investigate the biochemical properties of this novel enzyme and to define its substrate preferences. Null mutations exhibit pleiotropic phenotypes such as slow growth, reduced diploid formation and a sporulation defect. We will investigate the consequences of these pleiotropies by examining mitotic and meiotic nuclear division, spindle formation and the mating reaction. Genetic experiments will address these pleiotropies by in vitro mutagenesis of the TOP3 gene and by searching for genetic suppressors of these phenotypes. A slow growth suppressor, sgs1, has already been isolated and will be cloned and mapped using a modified Ty mutagenesis method that we will develop. Lastly, we will begin to investigate whether the TOP3 gene is a general feature of all cell by attempting to identify a homologue in the evolutionarily distant yeast Schizosaccharomyces pombe by using either nucleic acid homology or protein homology as a probe. It is our goal to understand the role that this novel topoisomerase plays in cells growth and development. The process of genetic recombination is observed in all living organisms. Although this process has important biological consequences both for individuals and for populations, and the details of its mechanism has been under intense study in a number of laboratories for years, we still do not have a good understanding of how this process helps living organisms survive. During his previous investigations into the mechanism of recombination in yeast, the author of this proposal discovered anew gene involved in this process; this gene encoded an enzyme of a type not previously seen in yeast or higher organisms. Mutants defective in this gene also had defects in many aspects of their life cycle. This is a proposal to investigate how this gene is involved with these other life processes.

我们已经分离出一个超重组突变体，TOP3， 鉴定了酵母中一种新的真核拓扑异构酶， 酿酒酵母 预测的开放阅读框架 TOP3基因与细菌类型I同源， 拓扑异构酶，TopA，但与真核I型或 II酶。 我们计划研究 并确定其底物偏好。 突变表现出多效性表型，如慢 生长、二倍体形成减少和孢子形成缺陷。 我们 将调查这些多效性的后果， 检查有丝分裂和减数分裂核分裂，纺锤体形成 和交配反应 基因实验将解决这些问题 通过TOP3基因的体外诱变和通过 寻找这些表型的遗传抑制因子。 一个缓慢 生长抑制因子SGS 1已经被分离出来， 克隆和映射使用修改的泰诱变方法，我们 将发展。 最后，我们将开始调查 TOP3基因是所有细胞的一般特征， 在进化上遥远的酵母中发现一个同源物 粟酒裂殖酵母通过使用任一核酸同源性 或蛋白质同源性作为探针。 我们的目标是了解 这种新型拓扑异构酶在细胞生长中的作用， 发展 基因重组的过程可以在 所有的生物体。 虽然这一过程具有重要意义， 对个体和群体的生物学后果， 其机制的细节一直在紧张的研究中， 多年来，我们一直没有一个很好的实验室。 了解这一过程如何帮助生物体生存。 在他以前调查的机制， 在酵母重组，该提案的作者发现， 参与这一过程的一种新基因;这种基因编码一种酶 以前在酵母或高等生物中没有发现的类型。 该基因缺陷的突变体在许多方面也存在缺陷 的生命周期。 这是一个研究如何 基因与其他生命过程有关。