Iron-sulfur (Fe-S) cluster assembly: the SufBCD complex is a new type of Fe-S scaffold with a flavin redox cofactor

Silke Wollers (1) , Gunhild Layer (1) , Ricardo Garcia-Serres (1) , Luca Signor (2) , Martin Clemancey (1) , Jean-Marc Latour (1) , Marc Fontecave (1, 3) , Sandrine Ollagnier de Choudens (1)

1 LCBM - UMR 5249 - Laboratoire de Chimie et Biologie des Métaux
2 IBS - UMR 5075 - Institut de biologie structurale
3 Collège de France - Chaire Chimie des processus biologiques

Assembly of iron-sulfur (Fe-S) clusters and maturation of Fe-S proteins in vivo require complex machineries. In Escherichia coli, under adverse stress conditions this process is achieved by the SUF system that contains six proteins: SufA, SufB, SufC, SufD, SufS and SufE. Here we provide a detailed characterization of the SufBCD complex whose function was so far unknown. Using biochemical and spectroscopic analyses we demonstrate that the complex (i) as isolated exists mainly in a 1:2:1 (B:C:D) stoichiometry, (ii) can assemble a [4Fe-4S] cluster in vitro and transfer it to target-proteins; and (iii) binds one molecule of a Flavin Adenine Dinucleotide per SufBC2D complex, only in its reduced form (FADH2), that has the ability to reduce ferric iron. These results suggest that the SufBC2D complex functions as a novel type of scaffold protein which assembles a Fe-S cluster through the mobilization of sulfur from the SufSE cysteine desulfurase and the FADH2-dependent reductive mobilization of Fe.

Domaines: Biochimie, Biologie Moléculaire

Silke Wollers, Gunhild Layer, Ricardo Garcia-Serres, Luca Signor, Martin Clemancey, et al.. Iron-sulfur (Fe-S) cluster assembly: the SufBCD complex is a new type of Fe-S scaffold with a flavin redox cofactor. Journal of Biological Chemistry, 2010, 285 (30), pp.23331-23341. ⟨10.1074/jbc.M110.127449⟩. ⟨hal-01053728⟩