The monothiol glutaredoxin GrxD is essential for sensing iron starvation in Aspergillus fumigatus
The monothiol glutaredoxin GrxD is essential for sensing iron starvation in Aspergillus fumigatus
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DOI：
10.1371/journal.pgen.1008379
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发表时间：
2019-09-01
期刊：
影响因子：
4.5
通讯作者：
Haas, Hubertus
中科院分区：
文献类型：
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作者：
Misslinger, Matthias;Scheven, Mareike Thea;Haas, Hubertus
对铁饥饿的有效适应是最常见的人类霉菌病原体烟曲霉的重要毒力决定因素。在这里，我们证明了细胞溶质的单巯基谷氧还蛋白GrxD在这种真菌的铁传感中起着至关重要的作用。我们的研究表明：（i）GrxD是生长所必需的;（ii）在铁充足的条件下，转录因子SreA抑制grxD的表达，而在铁饥饿的条件下，该基因的表达上调;（iii）在铁饥饿而非铁充足的条件下，GrxD显示出主要的核定位;（iv）grxD表达的下调导致参与铁依赖性途径的基因的去阻遏和参与铁饥饿期间铁获得的基因的阻遏，（v）GrxD显示与细胞溶质铁-硫簇生物合成机制的组分的蛋白质-蛋白质相互作用，表明在该过程中的作用，以及与转录因子SreA和HapX的蛋白质-蛋白质相互作用，所述转录因子SreA和HapX介导铁获得和铁依赖性途径的铁调节;（vi）重组HapX或HapX和GrxD的复合物的UV-Vis光谱表明铁-硫簇的配位;和（viii）存在一种GrxD非依赖性机制，用于通过HapX感知铁充足;（ix）SreA的失活抑制由GrxD失活引起的致死效应。综上所述，这项研究表明，GrxD是至关重要的铁稳态在A。烟曲霉是一种普遍存在的致病霉菌，是引起危及生命的曲霉病的主要病原体。为了改善治疗，迫切需要更好地了解真菌生理学。我们以前已经表明，适应铁饥饿是一个重要的毒力属性。烟熏。在本研究中，我们的特点是采用的机制，A。fumigatus来感知细胞铁状态，这对于铁稳态是必不可少的。我们证明，转录因子SreA和HapX，协调铁的收购，铁的消耗和铁解毒需要与单巯基谷胱甘肽谷胱甘肽还原酶GrxD的物理相互作用感铁饥饿。此外，我们发现，有一个GrxD独立的机制，用于检测过量的铁。
Efficient adaptation to iron starvation is an essential virulence determinant of the most common human mold pathogen, Aspergillus fumigatus. Here, we demonstrate that the cytosolic monothiol glutaredoxin GrxD plays an essential role in iron sensing in this fungus. Our studies revealed that (i) GrxD is essential for growth; (ii) expression of the encoding gene, grxD, is repressed by the transcription factor SreA in iron replete conditions and upregulated during iron starvation; (iii) during iron starvation but not iron sufficiency, GrxD displays predominant nuclear localization; (iv) downregulation of grxD expression results in de-repression of genes involved in iron-dependent pathways and repression of genes involved in iron acquisition during iron starvation, but did not significantly affect these genes during iron sufficiency; (v) GrxD displays protein-protein interaction with components of the cytosolic iron-sulfur cluster biosynthetic machinery, indicating a role in this process, and with the transcription factors SreA and HapX, which mediate iron regulation of iron acquisition and iron-dependent pathways; (vi) UV-Vis spectra of recombinant HapX or the complex of HapX and GrxD indicate coordination of iron-sulfur clusters; (vii) the cysteine required for iron-sulfur cluster coordination in GrxD is in vitro dispensable for interaction with HapX; and (viii) there is a GrxD-independent mechanism for sensing iron sufficiency by HapX; (ix) inactivation of SreA suppresses the lethal effect caused by GrxD inactivation. Taken together, this study demonstrates that GrxD is crucial for iron homeostasis in A. fumigatus.Author summary Aspergillus fumigatus is a ubiquitous saprophytic mold and the major causative pathogen causing life-threatening aspergillosis. To improve therapy, there is an urgent need for a better understanding of the fungal physiology. We have previously shown that adaptation to iron starvation is an essential virulence attribute of A. fumigatus. In the present study, we characterized the mechanism employed by A. fumigatus to sense the cellular iron status, which is essential for iron homeostasis. We demonstrate that the transcription factors SreA and HapX, which coordinate iron acquisition, iron consumption and iron detoxification require physical interaction with the monothiol glutaredoxin GrxD to sense iron starvation. Moreover, we show that there is a GrxD-independent mechanism for sensing excess of iron.