Fig. 1.

Ordered maturation of FeS clusters within mitochondria. Yfh1 binds the pre-formed Isu1–Nfs1(Isd11) complex facilitating FeS cluster synthesis. Other factors needed for cluster assembly include: yeast ferredoxin Yah1, which is functionally coupled with ferredoxin reductase Arh1, to provide electrons required for sulfur reduction. Jac1 displaces holo-Isu1 from the assembly complex to form the holo-Isu1–Jac1 complex. Ssq1 binds the PVK motif of holo-Isu1 in complex with Jac1. J-domain (J) of Jac1 stimulates the ATPase activity of Ssq1 facilitating FeS cluster transfer to the recipient apoprotein