Multi-domain CGFS-type glutaredoxin Grx4 regulates iron homeostasis via direct interaction with a repressor Fep1 in fission yeast

► Monothiol glutaredoxin Grx4 allows Fep1-mediated de-repression of iron uptake genes at low iron. ► Grx4 directly interacts with Fep1 in vivo and in vitro. ► The Cys172 in the CGFS motif of Grx4 is necessary for cell proliferation and iron regulation. ► The Cys172 of Grx4 is required for normal interaction with Fep1.