Metal Homeostatic Mechanisms in Yeast

描述（由申请人提供）：本申请集中于酵母酿酒酵母中细胞内铜（Cu）和铁（Fe）水平与基因表达的稳态偶联。铜吸收基因的金属调节受Mac 1转录激活因子控制。铁吸收基因的金属调节由两个相关的激活子Aft 1和Aft 2控制。这三个因子在金属缺乏的细胞中是转录激活因子，但在金属丰富的细胞中被特异性抑制。 主要目的是阐明铜离子传感器Mac 1和铁离子传感器Aft 1和Aft 2的机制。 酵母中Fe和Cu稳态之间存在许多相互联系。在过去的研究中，我们提供的证据表明，Mac 1通过直接结合Cu（I）离子来感知酵母细胞核内的Cu离子。 Cu（I）结合似乎诱导N-末端DNA结合结构域和C-末端反式激活结构域之间的分子内相互作用。研究提出，以验证直接感应铜和映射的分子内界面，抑制DNA结合和反式激活。 一个重要的目标是确定其他重要的酵母蛋白质，无论是铜穿梭到细胞核或铜抑制Mac 1。 酵母中的铁稳态由Aft 1和Aft 2调节。 铁抑制Aft 1和Aft 2功能的机制尚不清楚。 这些研究的意义在于S.酿酒酵母是理解转录调节子的铁传感机制的最佳模型真核系统。 我们建议，以确定铁传感是否发生通过直接铁结合，铁介导的翻译后修饰或通过另一种蛋白质？ Aft 1和Aft 2在酵母中表现出有限的功能冗余。 我们建议，以确定是否每一个表现出不同的生理功能。 Mac 1和Aft 1/Aft 2是研究营养调控gone表达的理想真核生物模型。 收集到的信息的机制，铜和铁的调节可能适用于其他物种。

DESCRIPTION (provided by applicant): 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.