CONTROL OF ENTRY INTO MEIOSIS IN YEAST

一个基本的生物学问题是， 离散的调节信号被识别和整合， 操纵基因表达这个问题直接影响到我们的 对发育和分化的控制的理解 更高的生物。酵母菌中孢子形成的过程 酿酒酵母是一个理想的模式系统， 真核生物的发育开关。这个简单的发展 程序依赖于多种监管影响，这些影响相互作用， 促进减数分裂和减数分裂形成的细胞类型特异性诱导 （统称为孢子形成）。MCK 1基因控制着 决定退出有丝分裂细胞周期并进入孢子形成 途径，并在介导着丝粒行为中起积极作用 在有丝分裂期间。MCK 1 p基因产物被认为是 一类新的蛋白激酶， 在丝氨酸、苏氨酸和酪氨酸上磷酸化靶蛋白 残基事实上，蛋白质磷酸化是一种常用的 真核细胞的信号转导机制，发育 规范的系统。因此，阐明作用机制 蛋白激酶的研究对于理解 生物体控制着分化、生长和发育。此外，委员会认为， 许多酪氨酸激酶与转化和 致癌潜力提供了额外的激励。这项建议 描述了旨在阐明MCK 1 通过鉴定控制减数分裂特异性基因表达， 表征其底物、靶标和调节剂。 MCK 1 p介导进入减数分裂响应细胞类型和 饥饿信号通过控制减数分裂激活剂的去阻遏 IME 1基因。因此，MCK 1 p靶点的磷酸化转导了 启动IME 1基因表达所需的信号。 我们建议：（1）确定和表征推定的底物 通过三种方法的组合：（a）分离突变体， mck 1缺陷的剂量依赖性抑制剂;（B）鉴定 与MCK 1 p物理相互作用的蛋白质;以及（c）鉴定 在IME 1启动子中的MCK 1-应答位点和 与这个网站互动。(2)探索监管影响， 通过分析激酶活性和底物特异性调节MCK 1 p 在已知影响进入减数分裂的条件下;以及（3）进行 体外激酶活性和底物特异性分析， 这类独特的蛋白激酶的特征。

One fundamental biological question is how cellular responses to discrete regulatory signals are recognized and integrated to precisely manipulate gene expression. This problem impacts directly on our understanding of the control of development and differentiation in higher organisms. The process of sporulation in the yeast Saccharomyces cerevisiae is an ideal model system for investigation of the control of developmental switches in eukaryotes. This simple developmental program relies on multiple regulatory influences which interact to promote cell-type-specific induction of meiosis and ascus formation (collectively referred to as sporulation). The MCK1 gene governs the decision to exit the mitotic cell cycle and enter the sporulation pathway, and plays a positive role in mediating centromere behavior during mitosis. The MCK1p gene product has been implicated as a member of a new class of protein kinase with the novel ability to phosphorylate target proteins on serine, threonine and tyrosine residues. Indeed, protein phosphorylation is a commonly exploited mechanism of signal transduction in eukaryotic, developmentally regulated systems. Therefore, elucidation of the mechanism of action of protein kinases is of paramount importance to understanding how an organism controls differentiation, growth and development. Furthermore, the association of many tyrosine kinases with transforming and oncogenic potential contributes added incentive. This proposal describes studies intended to elucidate the mechanism by which MCK1 controls meiotic-specific gene expression through identification and characterization of its substrates, targets and regulators. MCK1p mediates entry into meiosis in response to cell-type and starvation signals by controlling derepression of the meiotic activator gene IME1. Thus, phosphorylation of a target of MCK1p transduces the signal(s) required for initiation of IME1 gene expression. We propose to: (l) Identify and characterize putative substrates of MCK1p by a combination of three approaches: (a) isolation of mutant and dosage-dependent suppressors of an mck1 deficiency; (b) identification of proteins that physically interact with MCK1p; and (c) identification of the MCK1-Response Site in the IME1 promoter and factors that interact with this site. (2) Explore the regulatory influences that modulate MCK1p by analyzing kinase activity and substrate specificity under conditions known to affect entry into meiosis; and (3) Conduct in vitro kinase activity and substrate specificity analyses aimed at characterizing this unique class of protein kinase.