Yeast based model of anthrax lethal factor toxicity

描述（由申请人提供）：炭疽芽孢杆菌的致死因子是一种锌内源性蛋白酶，靶向丝裂原活化蛋白激酶（MEK）信号蛋白家族。该毒素识别该家族的特定成员，并切割mek与其下游效应物-丝裂原活化蛋白激酶（MAPKs）相互作用所需的基元。因此，多种MAPK通路被抑制，这损害了受影响细胞的活力。该项目的目标是开发一种体内筛选系统，可以快速识别有效和高度特异性的治疗方法。我们不会在体外筛选影响致死因子功能的特定方面的化合物（例如，毒素的蛋白水解活性或底物亲和力），而是选择使用特殊工程的出芽酵母酿酒酵母菌株来保护整个细胞免受致死因子毒性的分子。该酵母菌株将被设计成有条件地表达炭疽致死因子，并需要人类MEK的功能才能存活。当致命因子的表达开启时，MEK就会失活，细胞就会死亡。通过选择酵母细胞的活力，我们可以在几周内筛选数十万种化合物并识别出有效的抗毒素。这种方法的一个重要优点是它需要维护MEK功能。干扰MEK信号的药物不会通过筛选。该系统的另一个吸引人的特点是，与基于哺乳动物细胞的筛选相比，酵母由于其相对较快的生长速度，可以对病原体的新突变株做出更快的反应。除了提供概念证明外，我们还将优化基于酵母的系统，用于高通量筛选肽和cDNA文库，以及膜渗透性小分子的组合文库。

DESCRIPTION (provided by applicant): The lethal factor of Bacillus anthracis is a Zn-endoproteinase that targets the mitogen activated protein kinase kinase (MEK) family of signaling proteins. The toxin recognizes particular members of this family and cleaves a motif that is required for the interaction of MEKs with their downstream effectors--mitogen-activated protein kinases (MAPKs). As a consequence, multiple MAPK pathways are inhibited, and this impairs the viability of affected cells. The goal of this project is to develop an in vivo screening system that allows for the rapid identification of potent and highly specific therapeutics. Rather than screening for compounds that affect particular aspects of lethal factor function in vitro (e.g., its proteolytic activity of the toxin or substrate affinity), we will select for molecules that protect whole cells from lethal factor toxicity using specially engineered strains of the budding yeast Saccharomyces cerevisiae. The yeast strains will be designed to conditionally express anthrax lethal factor and to require the function of a human MEK for survival. When expression of the lethal factor is turned on, the MEK will be inactivated and the cells will die. By selecting for the viability of yeast cells, we can screen hundreds of thousands of compounds and identify potent anti-toxins in a matter of weeks. An important advantage of this approach is that it requires maintenance of MEK function. Agents that interfere with MEK signaling will not pass through the screen. Another attractive feature of this system is that in comparison to mammalian cell-based screens, yeast allow for a much faster response to new mutant strains of the pathogen due to its relatively rapid rate of growth. In addition to providing proof of concept, we will optimize the yeast-based system for high-throughput screening of peptide and cDNA libraries, as well as combinatorial libraries of membrane-permeable small molecules.