Department of Biology, Ball State University, Muncie, Indiana, United States.
Mode of Action and Resistance Management Center of Expertise, Corteva Agriscience, Indianapolis, Indiana, United States.
PeerJ. 2023 Aug 25;11:e15897. doi: 10.7717/peerj.15897. eCollection 2023.
is the most prevalent human fungal pathogen. In immunocompromised individuals, can cause serious systemic disease, and patients infected with drug-resistant isolates have few treatment options. The ubiquitin-proteasome system has not been thoroughly characterized in . Research from other organisms has shown ubiquitination is important for protein quality control and regulated protein degradation at the endoplasmic reticulum (ER) ER-associated protein degradation (ERAD).
Here we perform the first characterization, to our knowledge, of ERAD in a human fungal pathogen. We generated functional knockouts of genes encoding three proteins predicted to play roles in ERAD, the ubiquitin ligases Hrd1 and Doa10 and the ubiquitin-conjugating enzyme Ubc7. We assessed the fitness of each mutant in the presence of proteotoxic stress, and we used quantitative tandem mass tag mass spectrometry to characterize proteomic alterations in yeast lacking each gene.
Consistent with a role in protein quality control, yeast lacking proteins thought to contribute to ERAD displayed hypersensitivity to proteotoxic stress. Furthermore, each mutant displayed distinct proteomic profiles, revealing potential physiological ERAD substrates, co-factors, and compensatory stress response factors. Among candidate ERAD substrates are enzymes contributing to ergosterol synthesis, a known therapeutic vulnerability of . Together, our results provide the first description of ERAD function in , and, to our knowledge, any pathogenic fungus.
是最常见的人类真菌病原体。在免疫功能低下的个体中，可导致严重的全身疾病，而感染耐药分离株的患者几乎没有治疗选择。泛素-蛋白酶体系统在 中尚未得到彻底研究。来自其他生物体的研究表明，泛素化对于蛋白质质量控制和内质网（ER）中的调节蛋白降解（ERAD）很重要。
在这里，我们首次对人类真菌病原体中的 ERAD 进行了特征描述。我们生成了编码三种蛋白的基因的功能敲除，这些蛋白被预测在 ERAD 中发挥作用，泛素连接酶 Hrd1 和 Doa10 以及泛素缀合酶 Ubc7。我们评估了每种突变体在存在蛋白毒性应激时的适应性，并用定量串联质量标签质谱法对每个基因缺失的酵母中的蛋白质组变化进行了表征。
与蛋白质质量控制的作用一致，被认为有助于 ERAD 的酵母蛋白缺失表现出对蛋白毒性应激的敏感性增加。此外，每种突变体都显示出独特的蛋白质组谱，揭示了潜在的生理 ERAD 底物、共同因子和补偿应激反应因子。候选 ERAD 底物包括参与麦角固醇合成的酶，这是 的已知治疗弱点。总之，我们的结果首次描述了 ERAD 在 中的功能，并且据我们所知，在任何致病性真菌中都是如此。
