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The highly conserved protein, IscU, serves as the scaffold for iron-sulfur cluster (ISC) assembly in the ISC system common to bacteria and eukaryotic mitochondria. The apo-form of IscU from Escherichia coli has been shown to populate two slowly interconverting conformational states: one structured (S) and one dynamically disordered (D). Furthermore,(More)
IscU is a scaffold protein that functions in iron-sulfur cluster assembly and transfer. Its critical importance has been recently underscored by the finding that a single intronic mutation in the human iscu gene is associated with a myopathy resulting from deficient succinate dehydrogenase and aconitase [Mochel, F., Knight, M. A., Tong, W. H., Hernandez,(More)
The structural mechanism by which Hsp70-type chaperones interact with Hsp40-type co-chaperones has been of great interest, yet still remains a matter of debate. Here, we used solution NMR spectroscopy to investigate the ATP-/ADP-dependent interactions between Escherichia coli HscA and HscB, the specialized Hsp70/Hsp40 molecular chaperones that mediate(More)
IscU from Escherichia coli, the scaffold protein for iron-sulfur cluster biosynthesis and delivery, populates a complex energy landscape. IscU exists as two slowly interconverting species: one (S) is largely structured with all four peptidyl-prolyl bonds trans; the other (D) is partly disordered but contains an ordered domain that stabilizes two cis(More)
The scaffold protein for iron-sulfur cluster assembly, apo-IscU, populates two interconverting conformational states, one disordered (D) and one structured (S) as revealed by extensive NMR assignments. At pH 8 and 25 °C, approximately 70% of the protein is S, and the lifetimes of the states are 1.3 s (S) and 0.50 s (D). Zn(II) and Fe(II) each bind and(More)
The Escherichia coli isc operon encodes key proteins involved in the biosynthesis of iron-sulfur (Fe-S) clusters. Whereas extensive studies of most ISC proteins have revealed their functional properties, the role of IscX (also dubbed YfhJ), a small acidic protein encoded by the last gene in the operon, has remained in question. Previous studies showed that(More)
The Escherichia coli protein IscU serves as the scaffold for Fe-S cluster assembly and the vehicle for Fe-S cluster transfer to acceptor proteins, such as apoferredoxin. IscU populates two conformational states in solution, a structured conformation (S) that resembles the conformation of the holoprotein IscU-[2Fe-2S] and a dynamically disordered(More)
Escherichia coli [2Fe-2S]-ferredoxin (Fdx) is encoded by the isc operon along with other proteins involved in the 'house-keeping' mechanism of iron-sulfur cluster biogenesis. Although it has been proposed that Fdx supplies electrons to reduce sulfane sulfur (S(0)) produced by the cysteine desulfurase (IscS) to sulfide (S(2-)) as required for the assembly of(More)
SUMMARY PONDEROSA (Peak-picking Of Noe Data Enabled by Restriction of Shift Assignments) accepts input information consisting of a protein sequence, backbone and sidechain NMR resonance assignments, and 3D-NOESY ((13)C-edited and/or (15)N-edited) spectra, and returns assignments of NOESY crosspeaks, distance and angle constraints, and a reliable NMR(More)
Human ISCU is the scaffold protein for mitochondrial iron-sulfur (Fe-S) cluster biogenesis and transfer. NMR spectra have revealed that ISCU populates two conformational states; that is, a more structured state (S) and a partially disordered state (D). We identified two single amino acid substitutions (D39V and N90A) that stabilize the S-state and two (D39A(More)