In vivo iron-sulfur cluster formation

It has been proposed that iron-sulfur [Fe-S] clusters destined for the maturation of [Fe-S] proteins can be preassembled on a molecular scaffold designated IscU. In the present article, it is shown that production of the intact Azotobacter vinelandii [Fe-S] cluster biosynthetic machinery at levels e...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2008-06, Vol.105 (25), p.8591-8596
Main Authors: Raulfs, Estella C, O'Carroll, Ina P, Dos Santos, Patricia C, Unciuleac, Mihaela-Carmen, Dean, Dennis R
Format: Article
Language:English
Subjects:
Absorption spectra
Amino acids
Azotobacter vinelandii
Azotobacter vinelandii - metabolism
Bacteria
Bacterial Proteins - metabolism
Bacteriology
Biochemistry
Biological Sciences
Biosynthesis
Carbon-Sulfur Lyases - metabolism
Chromatography
Imidazoles
Iron
Iron-sulfur proteins
Iron-Sulfur Proteins - metabolism
Kinetics
Line spectra
Protein Subunits - chemistry
Protein Subunits - metabolism
Proteins
Scaffolds
Sulfur
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Summary:It has been proposed that iron-sulfur [Fe-S] clusters destined for the maturation of [Fe-S] proteins can be preassembled on a molecular scaffold designated IscU. In the present article, it is shown that production of the intact Azotobacter vinelandii [Fe-S] cluster biosynthetic machinery at levels exceeding the amount required for cellular maturation of [Fe-S] proteins results in the accumulation of: (i) apo-IscU, (ii) an oxygen-labile [2Fe-2S] cluster-loaded form of IscU, and (iii) IscU complexed with the S-delivery protein, IscS. It is suggested that these species represent different stages of the [Fe-S] cluster assembly process. Substitution of the IscU Asp³⁹ residue by Ala results in the in vivo trapping of a stoichiometric, noncovalent, nondissociating IscU-IscS complex that contains an oxygen-resistant [Fe-S] species. In aggregate, these results validate the scaffold hypothesis for [Fe-S] cluster assembly and indicate that in vivo [Fe-S] cluster formation is a dynamic process that involves the reversible interaction of IscU and IscS.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.0803173105