Fig 8. A proposed model of iron homeostasis regulated by FgAtm1 in F. graminearum.

FgAtm1 regulates the export of GSH-linked [2Fe-2S] clusters from mitochondria to cytoplasm, subsequently affects the assembly of cytoplasmic Fe-S proteins nitrite reductase (FgNiiA) and xanthine dehydrogenase (FgXdh) that are key enzymes for non-preferred nitrogen utilization. The activated FgNiiA and FgXdh inhibit the transcription of nitrogen metabolism regulator FgAreA. FgAreA activates expression of the transcription repressor FgHapX, subsequently regulates the transcription of iron-related genes in F. graminearum. In addition, the function of FgHapX is dependent on its interacting protein FgGrx4 and phosphorylation mediated by kinase FgYak1.