Examining the importance of folate biosynthetic enzymes in infectious fungi

叶酸生物合成(FOL)途径在叶酸生物合成(FOL)的研究中取得了巨大成功 抗癌、抗菌以及抗原虫药物。甲氨蝶呤和甲氧苄啶是一种有效的抑制剂。 哺乳动物和细菌的二氢叶酸还原酶(DHFR)，而一系列的磺胺类药物令人不安 二氢翼酸合酶在一些细菌和原生动物寄生虫中起作用。附加抗原虫药物 针对这一途径的药物还包括dhfr抑制剂乙胺嘧啶、普罗瓜尼和氯普瓜尼。 作为DHPS的抑制剂氨苯砜。然而，这些传统的抗叶酸药物几乎没有或几乎没有活性。 人类主要真菌病原体，要么是由于真菌酶结构的差异，要么是因为通透性 阻止它们进入真菌细胞的问题。此外，调整常规抗叶酸的努力 支架未能产生具有可行的抗真菌药物所需特性的衍生物，并集中于 几乎完全在DHFR上，其余的酶几乎完全没有任何特征 致病物种。我们建议利用这一途径开发抗真菌药物的努力应集中于 在FOL生物合成酶上，这些酶还没有成为重要研究的主题，并且 在哺乳动物中完全不存在。此外，他们应该寻找新的抗叶酸支架，这些支架对 整个真菌细胞。这项建议的目的是证实以真菌为靶点的有效性和可行性 Fol1p和Fol3p，它们共同拥有四种哺乳动物完全没有的FOL酶活性。在……里面 目的1我们将确认Fol1p和Fol3p蛋白在两种最常见的人类真菌中的重要性 病原菌、酵母菌、白色念珠菌和感染性霉菌烟曲霉，并建立了潜在的 利用侵袭性真菌小鼠模型靶向这些酶可达到的抗真菌效果 感染。在目标2中，我们将建立和验证高通量兼容的细胞和生化分析方法。 这可以用来确定这些酶活性的小分子抑制剂。总的来说，这些研究 将确定哺乳动物中不存在的FOL酶是否可以提供化学上易驯化和有效的 目标是设计新的抗真菌疗法，并可能产生能够形成这种基础的先导化合物 药物。

The folate biosynthetic (FOL) pathway has been targeted with enormous success in the development of anticancer, antibacterial as well as antiprotozoal drugs. Methotrexate and trimethoprim are potent inhibitors of mammalian and bacterial dihydrofolate reductase (DHFR) respectively, while a collection of ‘sulfa drugs’ perturb dihydropteroate synthase function in some bacterial as well as protozoan parasites. Additional antiprotozoal drugs that target this pathway include the DHFR inhibitors pyrimethamine, proguanil and chlorproguanil, as well as the DHPS inhibitor dapsone. However, these conventional antifolate drugs have little or no activity upon the major human fungal pathogens, either because of divergence of the fungal enzymes structure, or permeability issues that prevent them from entering fungal cells. Furthermore, efforts to adapt conventional antifolate scaffolds have failed to yield derivatives with the requisite properties of a viable antifungal drug and have focused almost exclusively upon DHFR, with the remaining enzymes almost completely uncharacterized in any pathogenic species. We propose that efforts to exploit this pathway for antifungal development should focus upon the FOL biosynthetic enzymes that have not yet been the subject of significant investigation and that are completely absent from mammals. In addition, they should seek novel antifolate scaffolds that are active upon whole fungal cells. The objective of this proposal is to substantiate the validity and feasibility of targeting fungal Fol1p and Fol3p, which together possess four FOL enzyme activities that are entirely absent from mammals. In aim 1 we will confirm the essentiality of the Fol1p and Fol3p proteins in two of the most prevalent human fungal pathogens, the yeast Candida albicans and the infectious mold Aspergillus fumigatus, and establish the potential antifungal efficacy that can be achieved in targeting these enzymes using mouse models of invasive fungal infection. In aim 2 we will establish and validate high-throughput compatible cell-based and biochemical assays that can be applied to identify small molecules inhibitors of these enzymes activity. Collectively, these studies will determine if FOL enzymes that are absent from mammals can provide chemically tractable and efficacious targets to devise new antifungal therapies and potentially yield lead compounds that can form the basis of such medications.