Iron-sulfur cluster assembly: characterization of IscA and evidence for a specific and functional complex with ferredoxin.
The synthesis of iron-sulfur clusters in Escherichia coli is believed to require a complex protein machinery encoded by the isc (iron-sulfur cluster) operon. The product of one member of this operon, IscA, has been overexpressed, purified, and characterized. It can assemble an air-sensitive [2Fe-2S] cluster as shown by UV-visible and resonance Raman spectroscopy. The metal form but not the apoform of IscA binds ferredoxin, another member of the isc operon, selectively, allowing transfer of iron and sulfide from IscA to ferredoxin and formation of the [2Fe-2S] holoferredoxin. These results thus suggest that IscA is involved in ferredoxin cluster assembly and activation. This is an important function because a functional ferredoxin is required for maturation of other cellular Fe-S proteins.
Ollagnier-de-Choudens
S
S
Laboratoire de Chimie et Biochimie des Centres Rédox Biologiques, DBMS-CB, CEA/CNRS/Université Joseph Fourier, UMR 5047, 17 Avenue des Martyrs, 38054 Grenoble Cedex 09, France.
Mattioli
T
T
Takahashi
Y
Y
Fontecave
M
M
D001426:Bacterial Proteins / Q000302:isolation & purification / Q000378:metabolism*; D001483:Base Sequence; D017931:DNA Primers; D004591:Electrophoresis, Polyacrylamide Gel; D005288:Ferredoxins / Q000378:metabolism*; D007506:Iron-Sulfur Proteins / Q000378:metabolism*; D009876:Operon; D011485:Protein Binding; D011994:Recombinant Proteins / Q000302:isolation & purification / Q000378:metabolism
D001426:Bacterial Proteins; D017931:DNA Primers; D005288:Ferredoxins; D007506:Iron-Sulfur Proteins; D011994:Recombinant Proteins