Crystal structure of Hsc20, a J-type Co-chaperone from Escherichia coli

J Mol Biol. 2000 Dec 15;304(5):835-45. doi: 10.1006/jmbi.2000.4252.


Hsc20 is a 20 kDa J-protein that regulates the ATPase activity and peptide-binding specificity of Hsc66, an hsp70-class molecular chaperone. We report herein the crystal structure of Hsc20 from Escherichia coli determined to a resolution of 1.8 A using a combination of single isomorphous replacement (SIR) and multi-wavelength anomalous diffraction (MAD). The overall structure of Hsc20 consists of two distinct domains, an N-terminal J-domain containing residues 1-75 connected by a short loop to a C-terminal domain containing residues 84-171. The structure of the J-domain, involved in interactions with Hsc66, resembles the alpha-topology of J-domain fragments of Escherichia coli DnaJ and human Hdj1 previously determined by solution NMR methods. The C-terminal domain, implicated in binding and targeting proteins to Hsc66, consists of a three-helix bundle in which two helices comprise an anti-parallel coiled-coil. The two domains make contact through an extensive hydrophobic interface ( approximately 650 A(2)) suggesting that their relative orientations are fixed. Thus, Hsc20, in addition to its role in the regulation of the ATPase activity of Hsc66, may also function as a rigid scaffold to facilitate positioning of the protein substrates targeted to Hsc66.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Amino Acid Substitution / genetics
  • Binding Sites
  • Conserved Sequence / genetics
  • Crystallography, X-Ray
  • Cysteine / genetics
  • Escherichia coli / chemistry*
  • Escherichia coli / genetics
  • Escherichia coli Proteins*
  • HSP40 Heat-Shock Proteins
  • Heat-Shock Proteins / chemistry*
  • Heat-Shock Proteins / genetics
  • Heat-Shock Proteins / metabolism
  • Humans
  • Models, Molecular
  • Molecular Chaperones / chemistry*
  • Molecular Chaperones / genetics
  • Molecular Chaperones / metabolism
  • Molecular Sequence Data
  • Nuclear Magnetic Resonance, Biomolecular
  • Protein Structure, Secondary
  • Protein Structure, Tertiary
  • Sequence Alignment
  • Static Electricity
  • Structure-Activity Relationship
  • Substrate Specificity


  • DNAJB1 protein, human
  • DnaJ protein, E coli
  • Escherichia coli Proteins
  • HSCB protein, human
  • HSP40 Heat-Shock Proteins
  • Heat-Shock Proteins
  • HscB protein, E coli
  • Molecular Chaperones
  • Cysteine

Associated data

  • PDB/1FPO