GENETIC REGULATION OF YEAST CELL TYPE

这项建议研究了细胞特化的分子基础，并 酿酒酵母中的细胞间通讯。在 酵母在其生命周期中表现出三个不同的细胞 表型。其中两种单元格类型a和alpha专用于 交配。它们的区别在于产生特定于细胞类型的 蛋白质，例如信息素和信息素受体，使 它们相互发出信号表示它们的存在，并为交配做准备。 这里提出的工作有两个广泛的目标。首先，我们想要 了解细胞特化的分子基础。差异化 产生a和α细胞类型的基因表达受 由阿尔法交配型编码的调节蛋白α1和α2 轨迹。这些蛋白质与一般转录结合在一起发挥作用。 控制α-特异性和a-特异性转录的因子MCM1 基因。一个非常小的MCM1片段就足以执行所有 它已知的功能。我们将对此片段进行突变以确定 与共同调节剂相互作用所需的残基 转录激活。此外，我们还将确定 与MCM1富含谷氨酰胺的片段相互作用 导致转录激活。 第二个目标是了解对信息素的反应途径。 信息素与其同源受体结合可激活信号 在反应中引起生理变化的转导途径 手机。这些变化包括通过有丝分裂阻止进展。 细胞周期和其产物基因转录的增加 催化交配。尽管反应途径中的几个步骤 组件之间的关系以及它们的 活动是否受到监管尚不清楚。我们将开展一项系统的 寻找表现出结构性主动反应途径的突变体。 我们还将通过分离突变株来鉴定新的途径组件 不能进行信息素反应的特定方面。例如, 我们将选择不能经历细胞周期停滞但 转录诱导正常。我们将订购 通过双突变分析，使用在此发现的突变 项目以及现有的变种人。我们将确定活动如何 蛋白激酶STE11是一种特殊的信号转导途径成分 受监管的。这一努力将以主导的属性为指导， 我们最近分离到的结构性STE11等位基因。最后，我们会 识别在受体上工作的功能，以减弱 信息素产生的信号，因此允许有丝分裂恢复生长。

This proposal examines the molecular basis of cell specialization and cell-cell communication in the yeast Saccharomyces cerevisiae. In the course of its life cycle yeast exhibits three distinct cellular phenotypes. Two of the cell types, a and alpha, are specialized for mating. They are distinguished by the production of cell-type-specific proteins, for example pheromones and pheromone receptors, that enable them to signal their presence to one another and prepare for mating. There are two broad goals for the work proposed here. First, we want to understand the molecular basis for cell specialization. The differential gene expression that generates the a and alpha cell types is governed by regulatory proteins, alpha1 and alpha2, encoded by the alpha mating-type locus. These proteins work in combination with a general transcription factor, MCM1, to control transcription of alpha-specific and a-specific genes. A remarkably small segment of MCM1 is sufficient to carry out all its known functions. We will mutagenize this segment to identify residues that are required for interaction with co-regulators and for transcription activation. In addition, we will identify functions that interact with a glutamine-rich segment of MCM1 that is also capable of bringing about transcription activation. The second goal is to understand the pathway of response to pheromone. Binding of pheromone to its cognate receptor activates a signal transduction pathway that elicits physiological changes in the responding cell. These changes include arrest of progression through the mitotic cell cycle and an increase in the transcription of genes whose products catalyze mating. Although several steps in the response pathway have been identified, the relationships among the components and how their activities are regulated is not known. We will carry out a systematic search for mutants that exhibit a constitutively active response pathway. We will also identify new pathway components by isolating mutants that cannot carry out particular aspects of pheromone response. For example, we will select for mutants that cannot undergo cell cycle arrest but are normal for transcription induction. We will order components of the pathway by double mutant analysis, using mutants identified in this project as well as existing mutants. We will determine how the activity of a particular pathway component, the protein kinase STE11, is regulated. This effort will be guided by the properties of dominant, constitutive STE11 alleles recently isolated by us. Finally, we will identify functions that operate at the receptor to attenuate the pheromone-generated signal and therefore allow mitotic growth to resume.