Three hydrophobic amino acids in Escherichia coli HscB make the greatest contribution to the stability of the HscB-IscU complex.

Background: General iron-sulfur cluster biosynthesis proceeds through assembly of a transient cluster on IscU followed by its transfer to a recipient apo-protein. The efficiency of the second step is increased by the presence of HscA and HscB, but the reason behind this is poorly understood. To shed light on the function of HscB, we began a study on the nature of its interaction with IscU.

Structure and dynamics of the iron-sulfur cluster assembly scaffold protein IscU and its interaction with the cochaperone HscB.

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.

Solution structure of the iron-sulfur cluster cochaperone HscB and its binding surface for the iron-sulfur assembly scaffold protein IscU.

The interaction between IscU and HscB is critical for successful assembly of iron-sulfur clusters. NMR experiments were performed on HscB to investigate which of its residues might be part of the IscU binding surface. Residual dipolar couplings ( (1) D HN and (1) D CalphaHalpha) indicated that the crystal structure of HscB [Cupp-Vickery, J.

X-ray diffraction analysis of a crystal of HscA from Escherichia coli.

HscA is a constitutively expressed Hsp70 that interacts with the iron-sulfur cluster assembly protein IscU. Crystals of a truncated form of HscA (52 kDa; residues 17-505) grown in the presence of an IscU-recognition peptide, WELPPVKI, have been obtained by hanging-drop vapor diffusion using ammonium sulfate as the precipitant. A complete native X-ray diffraction data set was collected from a single crystal at 100 K to a resolution of 2.

Crystal structure of the molecular chaperone HscA substrate binding domain complexed with the IscU recognition peptide ELPPVKIHC.

HscA, a specialized bacterial Hsp70-class molecular chaperone, interacts with the iron-sulfur cluster assembly protein IscU by recognizing a conserved LPPVK sequence motif. We report the crystal structure of the substrate-binding domain of HscA (SBD, residues 389-616) from Escherichia coli bound to an IscU-derived peptide, ELPPVKIHC. The crystals belong to the space group I222 and contain a single molecule in the asymmetric unit.

Crystal structure of IscA, an iron-sulfur cluster assembly protein from Escherichia coli.

IscA, an 11 kDa member of the hesB family of proteins, binds iron and [2Fe-2S] clusters, and participates in the biosynthesis of iron-sulfur proteins. We report the crystal structure of the apo-protein form of IscA from Escherichia coli to a resolution of 2.3A.

Identification of a novel candidate gene in the iron-sulfur pathway implicated in ataxia-susceptibility: human gene encoding HscB, a J-type co-chaperone.

Iron-sulfur proteins participate in a wide range of biochemical processes, including many that are central to mitochondrial electron transfer and energy metabolism. Mutations in two such proteins, frataxin and ABCB7, cause Friedreich ataxia and X-linked sideroblastic anemia with ataxia, respectively, rendering other participants in this pathway functional candidates for hereditary ataxia syndromes. Recently frataxin was shown to have an identical phylogenetic distribution with two genes and was most likely specifically involved in the same sub-process in iron-sulfur cluster assembly as one gene, designated hscB, in bacteria.

Hsc66 substrate specificity is directed toward a discrete region of the iron-sulfur cluster template protein IscU.

Hsc66 and Hsc20 comprise a specialized chaperone system important for the assembly of iron-sulfur clusters in Escherchia coli. Only a single substrate, the Fe/S template protein IscU, has been identified for the Hsc66/Hsc20 system, but the mechanism by which Hsc66 selectively binds IscU is unknown. We have investigated Hsc66 substrate specificity using phage display and a peptide array of IscU.