Biogenesis of Fe-S Cluster by the Bacterial Suf System
SufS AND SufE FORM A NEW TYPE OF CYSTEINE DESULFURASE*
- Laurent Loiseau‡§,
- Sandrine Ollagnier-de-Choudens§¶,
- Laurence Nachin‡∥,
- Marc Fontecave¶,** and
- Frédéric Barras‡‡‡
Abstract
Biosynthesis of iron-sulfur clusters (Fe-S) depends on multiprotein systems. Recently, we described the SUF system of Escherichia coli and Erwinia chrysanthemi as being important for Fe-S biogenesis under stressful conditions. The SUF system is made of six proteins: SufC is an atypical cytoplasmic ABC-ATPase, which forms a complex with SufB and SufD; SufA plays the role of a scaffold protein for assembly of iron-sulfur clusters and delivery to target proteins; SufS is a cysteine desulfurase which mobilizes the sulfur atom from cysteine and provides it to the cluster; SufE has no associated function yet. Here we demonstrate that: (i) SufE and SufS are both cystosolic as all members of the SUF system; (ii) SufE is a homodimeric protein; (iii) SufE forms a complex with SufS as shown by the yeast two-hybrid system and by affinity chromatography; (iv) binding of SufE to SufS is responsible for a 50-fold stimulation of the cysteine desulfurase activity of SufS. This is the first example of a two-component cysteine desulfurase enzyme.
- Received June 5, 2003.
- Revision received July 11, 2003.
- The American Society for Biochemistry and Molecular Biology, Inc.
