title: High-resolution solution structure of the 18 kDa substrate-binding domain of the mammalian chaperone protein Hsc70.
abstract: The three-dimensional structure for the substrate-binding domain of the mammalian chaperone protein Hsc70 of the 70 kDa heat shock class (HSP70) is presented. This domain includes residues 383-540 (18 kDa) and is necessary for the binding of the chaperone with substrate proteins and peptides. The high-resolution NMR solution structure is based on 4150 experimental distance constraints leading to an average root-mean-square precision of 0.38 A for the backbone atoms and 0.76 A for all atoms in the beta-sandwich sub-domain. The protein is observed to bind residue Leu539 in its hydrophobic substrate-binding groove by intramolecular interaction. The position of a helical latch differs dramatically from what is observed in the crystal and solution structures of the homologous prokaryotic chaperone DnaK. In the Hsc70 structure, the helix lies in a hydrophobic groove and is anchored by a buried salt-bridge. Residues involved in this salt-bridge appear to be important for the allosteric functioning of the protein. A mechanism for interdomain allosteric modulation of substrate-binding is proposed. It involves large-scale movements of the helical domain, redefining the location of the hinge area that enables such motions.
authors.affiliation: Department of Biological Chemistry,University of Michigan, Ann Arbor, 48109, USA.
authors.forename: R C
authors.initials: RC
authors.lastname: Morshauser
authors.forename: W
authors.initials: W
authors.lastname: Hu
authors.forename: H
authors.initials: H
authors.lastname: Wang
authors.forename: Y
authors.initials: Y
authors.lastname: Pang
authors.forename: G C
authors.initials: GC
authors.lastname: Flynn
authors.forename: E R
authors.initials: ER
authors.lastname: Zuiderweg
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002352:Carrier Proteins / Q000737:chemistry* / Q000378:metabolism; D029968:Escherichia coli Proteins; D050883:HSC70 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins / Q000737:chemistry* / Q000378:metabolism; D008322:Mammals; D018832:Molecular Chaperones / Q000737:chemistry* / Q000378:metabolism; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D011487:Protein Conformation; D051381:Rats; D017386:Sequence Homology, Amino Acid; D012996:Solutions; D013379:Substrate Specificity
chemical_list: D002352:Carrier Proteins; D029968:Escherichia coli Proteins; D050883:HSC70 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; C494373:Hspa8 protein, rat; D018832:Molecular Chaperones; D012996:Solutions; C063842:dnaK protein, E coli