1U00

HscA substrate binding domain complexed with the IscU recognition peptide ELPPVKIHC

Summary for 1U00

• Entry DOI: 10.2210/pdb1u00/pdb
• Descriptor: Chaperone protein hscA, IscU recognition peptide (3 entities in total)
• Functional Keywords: hsca, hsc66, dnak, hsp70, iscu, chaperone
• Biological source: Escherichia coli
• Total number of polymer chains: 2
• Total formula weight: 25452.96

Authors

Cupp-Vickery, J.R.,Peterson, J.C.,Ta, D.T.,Vickery, L.E. (deposition date: 2004-07-12, release date: 2004-10-05, Last modification date: 2024-04-03)

Primary citation

Cupp-Vickery, J.R.,Peterson, J.C.,Ta, D.T.,Vickery, L.E.
Crystal Structure of the Molecular Chaperone HscA Substrate Binding Domain Complexed with the IscU Recognition Peptide ELPPVKIHC.
J.Mol.Biol., 342:1265-1278, 2004

PubMed Abstract: 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. Molecular replacement with the E.coli DnaK(SBD) model was used for phasing, and the HscA(SBD)-peptide model was refined to Rfactor=17.4% (Rfree=21.0%) at 1.95 A resolution. The overall structure of HscA(SBD) is similar to that of DnaK(SBD), although the alpha-helical subdomain (residues 506-613) is shifted up to 10 A relative to the beta-sandwich subdomain (residues 389-498) when compared to DnaK(SBD). The ELPPVKIHC peptide is bound in an extended conformation in a hydrophobic cleft in the beta-subdomain, which appears to be solvent-accessible via a narrow passageway between the alpha and beta-subdomains. The bound peptide is positioned in the reverse orientation of that observed in the DnaK(SBD)-NRLLLTG peptide complex placing the N and C termini of the peptide on opposite sides of the HscA(SBD) relative to the DnaK(SBD) complex. Modeling of the peptide in the DnaK-like forward orientation suggests that differences in hydrogen bonding interactions in the binding cleft and electrostatic interactions involving surface residues near the cleft contribute to the observed directional preference.

PubMed: 15351650
DOI: 10.1016/j.jmb.2004.07.025

Experimental method

X-RAY DIFFRACTION (1.95 Å)