Frataxin Binds Iron Authored: Lill, R, 2012-09-24 Authored: May, B, 2011-06-04 Edited: May, B, 2011-06-04 Frataxin (FXN) specifically binds 2 atoms of ferrous iron per monomer (reviewed in Stemmler et al. 2010). Iron bound to Frataxin may (Yoon and Cowan 2003, Gerber et al. 2003) or may not (Schmucker et al. 2011) enhance the interaction of Frataxin with NFS1, ICSU, and ISD11. Frataxin was shown to stimulate the cysteine desulfurase activity of NFS1 and was proposed to be a regulator of sulfur production (Tsai et al. 2010). The formation of sulfide by NFS1 is most efficiently observed when NFS1 is in complex with ISD11, ISCU, and FXN in the presence of cysteine and iron. This means that only the complete system of NFS1, ISD11, ISCU, FXN, cysteine, and iron is fully active as a desulfurase. FXN therefore seems to be a regulator of the cysteine desulfurase permitting sulfide production only when all components needed for Fe-S cluster synthesis are present and the ISCU-bound Fe-S cluster can be formed. Pubmed11823441 Pubmed12785837 Pubmed15509595 Pubmed18425540 Pubmed20522547 Pubmed20873749 Pubmed21298097 Pubmed21776984 Reactome Database ID Release 431362416 Reactome, http://www.reactome.org ReactomeREACT_150163 Reviewed: Rouault, TA, 2012-10-11 Reviewed: Tong, Wing-Hang, 2012-10-11 has a Stoichiometric coefficient of 4 FXN:ISD11:NFS1:ISCU 2 Iron:FXN:NFS1:ISD11:ISCU