title: Cellular iron homeostasis mediated by the Mrs4-Ccc1-Smf3 pathway is essential for mitochondrial function, morphogenesis and virulence in Candida albicans.
abstract: Iron bioavailability is crucial for mitochondrial metabolism and biosynthesis. Dysregulation of cellular iron homeostasis affects multiple aspects of mitochondrial physiology and cellular processes. However, the intracellular iron trafficking pathway in Candida albicans remains unclear. In this study, we characterized the Mrs4-Ccc1-Smf3 pathway, and demonstrated its important role in maintaining cellular iron levels. Double deletion of vacuolar iron exporter SMF3 and mitochondrial iron transporter MRS4 further elevated cellular iron levels in comparison with the single MRS4 deletion. However, deletion of vacuolar iron importer CCC1 in the mrs4delta/delta mutant restored cellular iron homeostasis to normal wild-type levels, and also normalized most of the defective phenotypes in response to various environmental stresses. Our results also suggested that both Mrs4 and Cccl contributed to the maintenance of mitochondrial function. The mrs4delta/delta and mrs4delta/deltasmf3delta/delta mutants exhibited an obvious decrease in aconitase activities and mitochondrial membrane potential, whereas deletion of CCC1 in the mrs4delta/delta mutant effectively rescued these defects. Furthermore, we also found that the Mrs4-Ccc1-Smf3 pathway was indispensable for cell-wall stability, antifungal drug tolerance, filamentous growth and virulence, supporting the novel viewpoint that mitochondria might be the promising target for better antifungal therapies. Interestingly, the addition of exogenous iron failed to rescue the defects on non-fermentable carbon sources or hyphae-inducing medium, indicating that the defects in mitochondrial respiration and filamentous development might result from the disturbance of cellular iron homeostasis rather than environmental iron deprivation. Taken together, our results propose the Mrs4-Ccc1-Smf3 pathway as a potentially attractive target for antifungal drug development.
authors.forename: Ning
authors.initials: N
authors.lastname: Xu
authors.forename: Yijie
authors.initials: Y
authors.lastname: Dong
authors.forename: Xinxin
authors.initials: X
authors.lastname: Cheng
authors.forename: Qilin
authors.initials: Q
authors.lastname: Yu
authors.forename: Kiefan
authors.initials: K
authors.lastname: Qian
authors.forename: Jiwei
authors.initials: J
authors.lastname: Mao
authors.forename: Chang
authors.initials: C
authors.lastname: Jia
authors.forename: Xiaohui
authors.initials: X
authors.lastname: Ding
authors.forename: Bing
authors.initials: B
authors.lastname: Zhang
authors.forename: Yulu
authors.initials: Y
authors.lastname: Chen
authors.forename: Biao
authors.initials: B
authors.lastname: Zhang
authors.forename: Laijun
authors.initials: L
authors.lastname: Xing
authors.forename: Mingchun
authors.initials: M
authors.lastname: Li
mesh_terms: D000935:Antifungal Agents / Q000494:pharmacology; D001692:Biological Transport; D002176:Candida albicans / Q000187:drug effects / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity*; D027682:Cation Transport Proteins / Q000235:genetics / Q000378:metabolism*; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D006706:Homeostasis; D007501:Iron / Q000378:metabolism*; D053078:Membrane Potential, Mitochondrial / Q000502:physiology; D008928:Mitochondria / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D014774:Virulence
chemical_list: D000935:Antifungal Agents; D027682:Cation Transport Proteins; D005656:Fungal Proteins; D007501:Iron