Crystallographic analysis of the intact metal centres [3Fe-4S]1+/0 and [4Fe-4S]2+/1+ in a Zn2+-containing ferredoxin

Detailed structural models of di-cluster seven-iron ferredoxins constitute a valuable resource for folding and stability studies relating the metal cofactors' role in protein stability. The. here reported, hemihedric twinned crystal structure at 2.0 angstrom resolution from Acidianus ambivalens ferredoxin, shows an integral 103 residues, physiologically relevant native form composed by a N-terminal extension comprising a His/Asp Zn2+ site and the ferredoxin (beta alpha beta)(2) core, which harbours intact clusters I and II, a [3Fe-4S(]1+/0) and a [4Fe-4S](2+/1+) centres. This is in contrast with the previously available ferredoxin structure from Sulfolofus tokodai, which was obtained from an artificial oxidative conversion with two [3Fe-4S](1+/0) centres and poor definition around cluster II. (c) 2008 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.