Zhou Xiaogang, Yang Guorong, Li Chengxi, Yang Fan, Chang Xuelian
Anhui Key Laboratory of Infection and Immunity, School of Basic Medicine, Bengbu Medical College, Bengbu, China.
Front Microbiol. 2022 Aug 9;13:957857. doi: 10.3389/fmicb.2022.957857. eCollection 2022.
Drug resistance in fungal pathogens is a new challenge in clinical aspergillosis treatment. Mitochondria as dynamic organelles are involved in numerous biological processes in fungi, including drug resistance. However, little is known about the mechanism underlying mitochondrial regulation of the response of fungal pathogens to antifungal drugs. Here, we showed that a putative mitochondrial GTPase, GemA, a yeast Gem1 homolog, is crucial for the azole response and cell wall integrity in the opportunistic pathogen . The fluorescence observation showed that GFP-labeled GemA is located in mitochondria, and loss of results in aberrant giant mitochondrial morphology and abnormal mitochondrial membrane potential. Moreover, a Δ mutant attenuates fungal virulence in the model of aspergillosis. Furthermore, loss increases resistance to azoles and terbinafine but not to amphotericin B. Of note, RNA-seq combined with RT-qPCR showed that a series of drug efflux pumps were upregulated in the deletion mutant. Deleting or inhibiting the expression of drug efflux pumps can partially decrease the resistance to azoles resulting from the mutant, implying that GemA influences azole response by affecting the expression of drug efflux pumps. Importantly, the Δ mutant is susceptible to the cell wall-perturbing reagent CR, but not to CFW, and this defect can be partly rescued by hyperosmotic stress. TEM revealed that the cell wall of Δ was thicker than that of the WT strain, demonstrating that GemA plays a role in cell wall composition and integrity. Collectively, we identified a putative mitochondrial GTPase, GemA, which is critical for hyphal growth, virulence, azole susceptibility, and cell wall integrity and acts by affecting mitochondrial function.
真菌病原体中的耐药性是临床曲霉病治疗中的一个新挑战。线粒体作为动态细胞器，参与真菌的众多生物学过程，包括耐药性。然而，关于线粒体调节真菌病原体对抗真菌药物反应的潜在机制知之甚少。在这里，我们表明一种假定的线粒体GTP酶GemA（酵母Gem1的同源物）对机会性病原体中的唑类反应和细胞壁完整性至关重要。荧光观察表明，GFP标记的GemA位于线粒体中，其缺失导致异常的巨大线粒体形态和异常的线粒体膜电位。此外，Δ突变体在曲霉病模型中减弱了真菌毒力。此外，缺失会增加对唑类和特比萘芬的耐药性，但对两性霉素B不耐药。值得注意的是，RNA测序结合RT-qPCR表明，一系列药物外排泵在缺失突变体中上调。删除或抑制药物外排泵的表达可以部分降低由突变体引起的对唑类的耐药性，这意味着GemA通过影响药物外排泵的表达来影响唑类反应。重要的是，Δ突变体对细胞壁干扰试剂CR敏感，但对CFW不敏感，这种缺陷可以通过高渗胁迫部分挽救。透射电子显微镜显示，Δ的细胞壁比野生型菌株的厚，表明GemA在细胞壁组成和完整性中起作用。我们共同鉴定出一种假定的线粒体GTP酶GemA，它对菌丝生长、毒力、唑类敏感性和细胞壁完整性至关重要，并通过影响线粒体功能发挥作用。
