Targeted Fungal RAS Signaling for Antimicrobial Therapy

摘要：项目 2 – 用于抗菌治疗的靶向真菌 Ras 信号传导 重要的 Ras 信号转导途径的蛋白质已作为靶点进行了深入研究 抗癌疗法，而且在其他疾病中也具有潜力。我们找到了 Ras 的核心角色和 真菌发病机制中的 Ras 加工酶，特别是与病原体的高效能力相关 温度增长。我们的证据表明 Ras 通路抑制剂可以作为新疗法 治疗人类真菌疾病。许多化合物正处于临床前开发和临床试验中 抑制Ras，我们建议从这些已知的抑制剂开始设计具有改进抗真菌作用的药物 基于我们对蛋白质结构的了解的特性。 我们的目标是一种称为异戊烯基转移酶的酶，它可以修饰 Ras 蛋白，我们还将探索一种 第二组 Ras 修饰酶，棕榈酰转移酶。这两种蛋白质都是必需的 Ras 信号蛋白的正确定位；如果没有酶的活性，Ras 功能就会丧失。我们有 研究了哺乳动物异戊二烯基转移酶的结构并帮助开发了针对性的异戊二烯基转移酶 抑制剂。在最近的工作中，我们还解决了四种真菌异戊烯基转移酶的结构，FTase 和 GGTase，在不同的病原真菌中。我们的工作揭示了保守的分子特征 真菌酶，但与哺乳动物酶不同。这种真菌特有的特征表明，当前 抑制剂可以衍生化以增强抗真菌效果。我们的数据还表明 Ras 抑制将 与针对真菌钙调神经磷酸酶和海藻糖途径的疗法具有协同作用（项目 1 和 3）。 在这项提案中，我们建立并扩展了基于结构的研究，以开发新颖的协同、广泛的 谱抗真菌药。我们提出三个具体目标：1) 重新定向大量 FTase 抑制剂 （FTIs）使用结构引导方法开发抗真菌药物的癌症化疗药物。 2) 至 研究 GGTase 作为抗真菌药物靶点，并类似地使用结构引导开发有效的抑制剂 接近。 3) 研究Ras家族蛋白的棕榈酰化在真菌发病机制中的作用，并评价其作用 治疗靶向的潜力。棕榈酰转移酶在真菌和哺乳动物之间存在很大差异，并且 我们提出的遗传和生化研究将允许集中筛选和优化 棕榈酰化抑制剂作为新型抗真菌药。该项目将利用所有三个核心并与 该计划的项目 1 和 2 旨在加速治疗生命的新型药物的开发 威胁人类的真菌感染。

ABSTRACT: Project 2 – Targeted Fungal Ras Signaling for Antimicrobial Therapy Proteins of the important Ras signal transduction pathway have been intensely studied as targets for anticancer therapeutics, but also hold potential in other diseases. We have found central roles for Ras and Ras-processing enzymes in fungal pathogenesis, particularly related to pathogens' capability for high temperature growth. Our evidence suggests that inhibitors of the Ras pathway could serve as novel therapies to treat human fungal diseases. Numerous compounds are in preclinical development and in clinical trials that inhibit Ras, and we propose to start from these known inhibitors to design agents with improved antifungal properties based on our knowledge of the proteins' structures. Our targets are enzymes called prenyltransferases that modify Ras proteins, and we also will explore a second set of Ras-modifying enzymes, the palmitoyltransferases. Both of these proteins are required for proper localization of Ras signaling proteins; without the enzymes' activities, Ras function is lost. We have studied the structure of mammalian prenyltransferases and have helped develop focused prenyltransferase inhibitors. In more recent work, we also have solved the structures of four fungal prenyltransferases, FTase and GGTase, in different pathogenic fungi. Our work has revealed molecular features that are conserved in the fungal enzymes but differ from the mammalian ones. Such fungal-specific features suggest that current inhibitors could be derivatized for enhanced antifungal effect. Our data also indicate that Ras inhibition will be synergistic with therapies directed against fungal calcineurin and trehalose pathways (Projects 1 and 3). In this proposal, we build on and expand our structure-based studies to develop novel synergistic, broad- spectrum antifungals. We propose three Specific Aims: 1) To redirect the large collections of FTase inhibitors (FTIs) developed for cancer chemotherapeutics to antifungal agents using structure-guided approaches. 2) To investigate GGTase as an antifungal drug target, and similarly develop potent inhibitors using structure-guided approaches. 3) To investigate palmitoylation of Ras-family proteins in fungal pathogenesis, and evaluate its potential for therapeutic targeting. Palmitoyltransferases are highly divergent between fungi and mammals, and our proposed genetic and biochemical studies will allow the focused screening and optimization of palmitoylation inhibitors as new antifungals. This Project will utilize all three Cores and interact closely with Projects 1 and 2 of this Program Project in order to accelerate development of novel agents to treat life- threatening fungal infections in humans.