Inhibiting sequential biosynthetic steps of a fungal-specific organelle

项目总结/摘要 在美国，白色念珠菌是最常见的引起侵袭性疾病的真菌。 这些感染是严重疾病的可怕并发症，特别是在住院或 免疫功能低下的患者。C.白色念珠菌感染是具有挑战性的根除， 导致20%的患者死亡目前只有3类抗真菌药物可用 来治疗侵袭性真菌感染抗真菌药物的开发是困难的，因为它们之间的相似性。 真菌和人类细胞，这导致许多破坏或杀死真菌的化合物的不可接受的毒性。 开发靶点在人类细胞中不存在的抗真菌剂将克服这一困难。 增加抗真菌药物的效力也可能导致更好的结果。一个范例， 复方新诺明是一种重要的复方抗生素，其两组分作用靶点 四氢叶酸生物合成中的连续步骤。 该提案的目标是找到可以开发成两种特异性抑制剂的化合物， 真菌特有的细胞过程，它们的结合可以产生更有效的抗真菌剂。 两种真菌细胞过程是根本不同的或在人类中不存在的是磷酸盐 稳态和细胞壁构建。我们以前发现，主要的C。高亲和力白念珠菌 磷酸转运蛋白Pho84是正常营养（雷帕霉素靶）信号传导、细胞壁 胁迫和氧化胁迫抗性、菌丝生长和毒力。因为人类管理他们的 磷酸盐平衡与真菌完全不同，阻断Pho84预计不会影响人类 细胞功能。Pho84在真菌界高度保守，包括在新出现的病原体中 比如耳念珠菌缺乏Pho84的细胞含有减少浓度的核苷酸， 生产需要充足的细胞内磷酸盐供应，以及它们的下游代谢物， 核苷酸糖。核苷酸糖是生物合成主要细胞壁聚合物的前体。我们 我建议利用这一缺陷，通过以下方式依次干扰细胞壁生物合成中的主要步骤 将抑制Pho84与抑制葡聚糖生物合成相结合。为了做到这一点，我们建立了一个小说， 高通量分析系统来检测这些真菌靶标的特异性抑制剂。我们会优先打击 根据其在毒性相关或必需细胞过程中的生物学效应， 根据它们的化学特征。这项工作将奠定基础，应用范例的逐步 抑制抗真菌药物开发的关键生物合成过程。该提案意在 选择符合规定的生物学和药物化学标准的筛选结果用于进一步开发。

PROJECT SUMMARY/ABSTRACT Candida albicans is the most frequently isolated fungus causing invasive disease in the United States. These infections are dreaded complications of serious illnesses, especially in hospitalized or immunocompromised patients. C. albicans infections are challenging to eradicate, and are still estimated to lead to death in 20% of the affected patients. Currently only 3 classes of antifungal drugs are available to treat invasive fungal infections. Antifungal drug development is difficult because of the similarity between fungal and human cells, which leads to unacceptable toxicity of many compounds that damage or kill fungi. Developing antifungal agents whose targets are absent in human cells would circumvent this difficulty. Increasing potency of antifungal drugs could also lead to better outcomes. A paradigm for increased antimicrobial potency is the important combination antibiotic Cotrimoxazole, whose two components target sequential steps in the biosynthesis of tetrahydrofolate. The goal of this proposal is to find compounds that can be developed into specific inhibitors of two cellular processes unique to fungi, whose combination could give rise to a more potent antifungal agent. Two fungal cellular processes that are fundamentally different or absent in humans are phosphate homeostasis and cell wall construction. We previously found that the major C. albicans high-affinity phosphate transporter Pho84 is required for normal nutritional (Target of Rapamycin-) signaling, cell wall stress- and oxidative stress resistance, hyphal growth and virulence. Since humans manage their phosphate balance completely differently from fungi, blocking Pho84 is not predicted to impact human cellular functions. Pho84 is highly conserved across the fungal kingdom, including in emerging pathogens like Candida auris. Cells that lack Pho84 contain diminished concentrations of nucleotides, whose production requires ample intracellular phosphate supplies, and of their downstream metabolites, nucleotide sugars. Nucleotide sugars are precursors for biosynthesis of the major cell wall polymers. We propose to take advantage of this defect to sequentially perturb major steps in cell wall biosynthesis by combining inhibition of Pho84 with inhibition of glucan biosynthesis. To do this, we established a novel high-throughput assay system to detect specific inhibitors of these fungal targets. We will prioritize hit compounds according to their biological effects in virulence-associated or essential cellular processes, and according to their chemical features. This work will lay the ground to apply the paradigm of stepwise inhibition of a critical biosynthetic process to antifungal drug development. The proposal is intended to select screen hits that meet defined biological and medicinal chemistry criteria for further development.