Fungal mitochondria govern both gliotoxin biosynthesis and self-protection

Gliotoxin (GT) is a potent epipolythiodioxopiperazine toxin produced by the opportunistic pathogen Aspergillus fumigatus that contributes to virulence and inhibits competing microorganisms. However, GT is highly toxic to the producer itself, necessitating robust self-protection mechanisms. Here, we used a comparative transcriptomics approach between A. fumigatus (GT producer) and A. nidulans (non-producer) to identify additional genetic determinants of GT self-protection downstream of the transcription factor RglT. We characterized five RglT-dependent genes: abcC1 (ABC transporter), mfsD (major facilitator superfamily transporter), oxrA (oxidoreductase), mtrA (putative methyltransferase), and nmrC (a GATA-type repressor). Deletion mutants in A. fumigatus and A. nidulans revealed that all except oxrA were required for full GT protection, with ΔmtrA and ΔnmrC exhibiting distinct phenotypes in oxidative stress and iron-starvation conditions. Transcriptomic profiling and protein network analysis showed that MtrA and NmrC influence mitochondrial functions, particularly ubiquinone biosynthesis, despite not localizing to mitochondria. Functional assays confirmed that GT exposure disrupts mitochondrial integrity and sensitizes A. fumigatus to mitochondrial inhibitors. Notably, GT-induced cell death was associated with mitochondrial fragmentation but lacked hallmarks of apoptosis-like nuclear damage. Together, our findings reveal new genetic components of GT detoxification and establish a critical role for mitochondrial function in A. fumigatus GT self-protection and production.胶霉毒素（Gliotoxin, GT）是一种强效的表硫代二氧哌嗪类毒素（epipolythiodioxopiperazine toxin），由机会致病菌烟曲霉（Aspergillus fumigatus）产生，可增强致病菌毒力并抑制竞争性微生物。然而，GT对其产生菌本身具有极高毒性，因此需要完善的自我保护机制。本研究采用烟曲霉（GT产生菌）与构巢曲霉（Aspergillus nidulans，非GT产生菌）的比较转录组学方法，在转录因子RglT的下游筛选GT自我保护的额外遗传决定因子。我们鉴定了5个依赖RglT的基因：abcC1（ABC转运蛋白，ABC transporter）、mfsD（主要促进物超家族转运蛋白，major facilitator superfamily transporter）、oxrA（氧化还原酶，oxidoreductase）、mtrA（推定甲基转移酶，putative methyltransferase）以及nmrC（GATA型阻遏蛋白，GATA-type repressor）。对烟曲霉和构巢曲霉的缺失突变体分析显示，除oxrA外，其余基因均为实现完全GT保护所必需；其中ΔmtrA与ΔnmrC突变体在氧化应激与铁饥饿条件下表现出独特的表型。转录组分析与蛋白质网络分析表明，尽管MtrA与NmrC并不定位于线粒体，二者却可影响线粒体功能，尤其是泛醌的生物合成。功能实验证实，GT暴露会破坏线粒体完整性，并使烟曲霉对线粒体抑制剂更为敏感。值得注意的是，GT诱导的细胞死亡与线粒体碎裂相关，但未出现类凋亡的核损伤特征。综上，本研究揭示了GT解毒通路中新的遗传组分，并证实线粒体功能在烟曲霉的GT自我保护与GT生产中发挥关键作用。