Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520, USA.
Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520, USA; Department of Chemistry, Yale University, New Haven, CT 06520, USA; Howard Hughes Medical Institute, Yale University, New Haven, CT 06520, USA.
J Mol Biol. 2024 Apr 15;436(8):168513. doi: 10.1016/j.jmb.2024.168513. Epub 2024 Mar 5.
Systemic fungal infections are a growing public health threat, and yet viable antifungal drug targets are limited as fungi share a similar proteome with humans. However, features of RNA metabolism and the noncoding transcriptomes in fungi are distinctive. For example, fungi harbor highly structured RNA elements that humans lack, such as self-splicing introns within key housekeeping genes in the mitochondria. However, the location and function of these mitochondrial riboregulatory elements has largely eluded characterization. Here we used an RNA-structure-based bioinformatics pipeline to identify the group I introns interrupting key mitochondrial genes in medically relevant fungi, revealing their fixation within a handful of genetic hotspots and their ubiquitous presence across divergent phylogenies of fungi, including all highest priority pathogens such as Candida albicans, Candida auris, Aspergillus fumigatus and Cryptococcus neoformans. We then biochemically characterized two representative introns from C. albicans and C. auris, demonstrating their exceptionally efficient splicing catalysis relative to previously-characterized group I introns. Indeed, the C. albicans mitochondrial intron displays extremely rapid catalytic turnover, even at ambient temperatures and physiological magnesium ion concentrations. Our results unmask a significant new set of players in the RNA metabolism of pathogenic fungi, suggesting a promising new type of antifungal drug target.
系统性真菌感染是一个日益严重的公共卫生威胁，而有效的抗真菌药物靶点却很有限，因为真菌与人类的蛋白质组有相似之处。然而，RNA 代谢和真菌中非编码转录组的特征是独特的。例如，真菌中存在着高度结构化的 RNA 元件，而人类则没有，例如线粒体中关键管家基因内的自我剪接内含子。然而，这些线粒体核糖调节元件的位置和功能在很大程度上仍未得到描述。在这里，我们使用基于 RNA 结构的生物信息学管道来鉴定医学相关真菌中断关键线粒体基因的 I 组内含子，揭示了它们在少数遗传热点中的固定性以及它们在真菌的不同进化枝中的普遍存在性，包括所有最高优先级的病原体，如白色念珠菌、耳念珠菌、烟曲霉和新型隐球菌。然后，我们对来自白色念珠菌和耳念珠菌的两个代表性内含子进行了生化表征，证明它们相对于以前表征的 I 组内含子具有极高的剪接催化效率。事实上，白色念珠菌的线粒体内含子显示出极其快速的催化周转，即使在环境温度和生理镁离子浓度下也是如此。我们的研究结果揭示了病原真菌 RNA 代谢中的一组重要的新参与者，这表明了一种有前途的新型抗真菌药物靶点。
