YEAST ESS1, A CONSERVED PPIASE ESSENTIAL FOR MITOSIS

酵母和人类细胞需要ESS1基因才能分裂。 这种重要的基因通过有丝分裂控制细胞周期的进程， 鉴于其非同寻常的保护，可能在所有方面都需要 真核生物。这项工作的目标是了解ESS1是如何 控制细胞周期。酵母酿酒酵母， 发现ESS1的生物体将被用作模型 系统。ESS1在结构和结构上都高度保守 功能上；ESS1同源物来自果蝇和黑腹果蝇 人类拯救了酵母ESS1突变体。Ess1蛋白及其相关基因 对应的蛋白质是已知的唯一既包含WW又包含WW的蛋白质 结构域和PPIase(肽基-脯氨基异构酶)结构域。万维网 结构域是蛋白质中的一种蛋白质相互作用模块 如肌营养不良蛋白，由人类肌肉营养不良症编码 吉恩。PPIase结构域是一个催化模块，控制着 激酶、受体和转录因子的折叠和活性 并在亲环素等蛋白质中发现，这些蛋白质介导了 免疫抑制药。这些域在Ess1中如何发挥作用 对细胞周期的控制尚不清楚。在这项提案中，酵母遗传学 将用于了解Ess1如何控制有丝分裂进程和 WW和PPIase域对此活动的贡献。这 将通过(1)实施广泛的结构来实现- Ess1 WW和PPIase结构域的功能分析，(2)通过 分离ESS1基因的条件等位基因并利用这些等位基因 细胞周期分析，以及(3)通过鉴定细胞周期的其他成分 利用抑制子筛选和双杂交选择的ESS1通路。 了解ESS1在酵母中的功能将有助于 对有丝分裂调节的途径知之甚少，并将提供 洞察所有真核细胞中细胞周期的控制。

Yeast and human cells require the ESS1 gene in order to divide. This essential gene controls cell cycle progression through mitosis, and given its extraordinary conservation, is probably required in all eukaryotes. The goal of this work is to understand how ESS1 controls the cell cycle. The yeast saccharomyces cerevisiae, the organism in which ESS1 was discovered, will be used as a model system. ESS1 is highly conserved both structurally and functionally; ESS1 homologs from Drosophila melanogaster and humans rescue yeast ess1 mutants. The Ess1 protein and its counterparts are the only known proteins to contain both a WW domain and a PPIase (peptidyl-prolyl isomerase) domain. The WW domain is a protein-protein interaction module found in proteins such as Dystrophin, encoded by the human muscular dystrophy gene. The PPIase domain is a catalytic module that controls the folding and activity of kinases, receptors and transcription factors and is found in proteins like cyclophilin that mediate the effects of immunosuppressive drugs. How these domains function in Ess1 to control the cell cycle is not known. In this proposal, yeast genetics will be used understand how Ess1 controls mitotic progression and how the WW and PPIase domains contribute to this activity. This will be accomplished by (1) conducting an extensive structure- function analysis of the Ess1 WW and PPIase domains, (2) by isolating conditional alleles of ESS1 gene and using these alleles for cell cycle analysis, and (3) by identifying other components of the ESS1 pathway using suppressor screens and tow-hybrid selections. An understanding of how ESS1 functions in yeast will illuminate poorly understood pathways of mitotic regulation and will provide insight into the control of the cell cycle in all eukaryotic cells.