Glutaredoxins: roles in iron homeostasis.

Glutaredoxins, proteins traditionally involved in redox reactions, are also required for iron-sulfur cluster assembly and haem biosynthesis. These new roles are probably related to the ability of some glutaredoxins to bind labile [2Fe-2S] clusters and to transfer them rapidly and efficiently to acceptor proteins. Recent results point to putative roles for glutaredoxins in the sensing of cellular iron and in iron-sulfur cluster biogenesis, either as scaffold proteins for the de novo synthesis of iron-sulfur clusters or as carrier proteins for the transfer of preformed iron-sulfur clusters. Based on prokaryote genome analysis and in vivo studies of iron regulation in yeast, we propose putative new roles and binding partners for glutaredoxins in the assembly of metalloproteins.