Metal Homeostatic Mechanisms in Yeast

超出提供的空间。这一应用侧重于酵母细胞内铜(铜)和铁(铁)水平与基因表达的动态平衡耦合。铜摄取基因的金属调控是由MAC1转录激活因子控制的。铁摄取基因的金属调控由两个相关的激活因子Aft1和Aft2控制。这三个因子在金属缺乏的细胞中是转录激活剂，但在金属充足的细胞中被特异性地抑制。主要目的是阐明MAC1对铜离子的传感和Aft1和Aft2对Fe离子的传感机制。酵母中铁和铜的动态平衡之间存在着许多相互联系。在过去的授权周期中，我们提供的证据表明，MAC1通过与铜(I)离子直接结合而感测酵母核内的铜离子。铜(I)结合似乎诱导了N端DNA结合域和C端反式激活域之间的分子内相互作用。有人建议进行研究，以验证铜的直接传感，并绘制抑制DNA结合和反式激活的分子内界面。一个重要的目标是确定在铜穿梭到细胞核或铜抑制MAC1的过程中起重要作用的其他酵母蛋白。酵母铁稳态受Aft1和Aft2调控。铁抑制Aft1和Aft2功能的机制尚不清楚。这些研究的意义在于，酿酒酵母是了解铁的转录调控机制的最好的模式真核系统。我们建议确定铁感应是通过直接铁结合、铁介导的翻译后修饰还是通过另一种蛋白质发生的？Aft1和Aft2在酵母中表现出有限的功能冗余。我们建议确定是否每一个都表现出不同的生理功能。MAC1和Aft1/Aft2是研究Gone表达营养调控的良好模式真核系统。有关铜、铁调控机制的信息可能也适用于其他物种。表演网站========================================Section End===========================================

EXCEED THE SPACE PROVIDED. This application focuses on homeostatic coupling of intracellular copper (Cu) and iron (Fe) levels to gene expression in the yeast Saccharomyces cerevisiae. Metalloregulation of Cu uptake genes is controlled by the Mac1 transcriptional activator. Metalloregulation of Fe uptake genes is controlled by two related activators, Aft1 and Aft2. These three factors are transcriptional activators in metal-deficient cells, but specifically inhibited in metal-replete cells. The major objectives are to elucidate the mechanisms of Cu ion sensing by Mac1 and Fe ion sensing by Aft1 and Aft2. Many interconnections exist between Fe and Cu homeostasis in yeast. In the past grant cycle we provided evidence suggestive that Mac1 senses Cu ions within the yeast nucleus through direct binding of Cu(I) ions by Mac1. Cu(I) binding appears to induce an intramolecular interaction between the N-terminal DNA binding domain and C-terminal transactivation domain. Studies are proposed to verify direct sensing of Cu and to map the intramolecular interface that inhibits both DNA binding and transactivation. An important goal is to identify other yeast proteins important in either Cu shuttling to the nucleus or Cu inhibition of Mac1. Fe-homeostasis in yeast is regulated by Aft1 and Aft2. The mechanism of Fe inhibition of Aft1 and Aft2 function is unknown. The significance of these studies is that S. cerevisiae is the best model eukaryotic system to understand the mechanism of Fe sensing by a transcription regulator. We propose to determine whether Fe sensing occurs through direct Fe binding, Fe-mediated post-translational modification or through another protein? Aft1 and Aft2 exhibit limited functional redundancy in yeast. We propose to determine whether each exhibits a distinct physiological function. Mac1 and Aftl/Aft2 are excellent model eukaryotic systems to study nutritional control of gone expression. Information gleaned on the mechanism of Cu- and Fe-regulation may be applicable to other species. PERFORMANCE SITE ========================================Section End===========================================