Iron-Sulfur (Fe-S) Cluster Assembly: THE SufBCD COMPLEX IS A NEW TYPE OF Fe-S SCAFFOLD WITH A FLAVIN REDOX COFACTOR

• Published in: The Journal of biological chemistry Vol. 285; no. 30; pp. 23331 - 23341
• Main Authors: Wollers, Silke, Layer, Gunhild, Garcia-Serres, Ricardo, Signor, Luca, Clemancey, Martin, Latour, Jean-Marc, Fontecave, Marc, Ollagnier de Choudens, Sandrine
• Format: Journal Article
• Language: English
• Published: United States American Society for Biochemistry and Molecular Biology 23-07-2010
• Subjects: Adenosine Triphosphatases - chemistry; Adenosine Triphosphatases - metabolism; Amino Acid Sequence; Anaerobiosis; Biochemistry, Molecular Biology; Carrier Proteins - chemistry; Carrier Proteins - metabolism; Escherichia coli - metabolism; Escherichia coli Proteins - chemistry; Escherichia coli Proteins - metabolism; Flavin-Adenine Dinucleotide - analogs & derivatives; Flavin-Adenine Dinucleotide - metabolism; Iron-Sulfur Proteins - chemistry; Iron-Sulfur Proteins - metabolism; Life Sciences; Metabolism; Molecular Sequence Data; Oxidants - metabolism; Oxidation-Reduction; Protein Synthesis and Degradation
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M110.127449

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 as follows: 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 the following: (i) the complex as isolated exists mainly in a 1:2:1 (B:C:D) stoichiometry; (ii) the complex can assemble a [4Fe-4S] cluster in vitro and transfer it to target proteins; and (iii) the complex binds one molecule of flavin adenine nucleotide per SufBC₂D complex, only in its reduced form (FADH₂), which has the ability to reduce ferric iron. These results suggest that the SufBC₂D complex functions as a novel type of scaffold protein that assembles an Fe-S cluster through the mobilization of sulfur from the SufSE cysteine desulfurase and the FADH₂-dependent reductive mobilization of iron.