The C-terminal (331-376) sequence of Escherichia coli DnaJ is essential for dimerization and chaperone activity: a small angle X-ray scattering study in solution

J Biol Chem. 2005 Jun 17;280(24):22761-8. doi: 10.1074/jbc.M503643200. Epub 2005 Apr 21.


DnaJ, an Escherichia coli Hsp40 protein composed of 376 amino acid residues, is a chaperone with thioldisulfide oxidoreductase activity. We present here for the first time a small angle x-ray scattering study of intact DnaJ and a truncated version, DnaJ (1-330), in solution. The molecular weight of DnaJ and DnaJ (1-330) determined by both small angle x-ray scattering and size-exclusion chromatography provide direct evidence that DnaJ is a homodimer and DnaJ (1-330) is a monomer. The restored models show that DnaJ is a distorted omega-shaped dimeric molecule with the C terminus of each subunit forming the central part of the omega, whereas DnaJ (1-330) exists as a monomer. This indicates that the deletion of the C-terminal 46 residues of DnaJ impairs the association sites, although it does not cause significant conformational changes. Biochemical studies reveal that DnaJ (1-330), while fully retaining its thiol-disulfide oxidoreductase activity, is structurally less stable, and its peptide binding capacity is severely impaired relative to that of the intact molecule. Together, our results reveal that the C-terminal (331-376) residues are directly involved in dimerization, and the dimeric structure of DnaJ is necessary for its chaperone activity but not required for the thiol-disulfide oxidoreductase activity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Chromatography
  • Dimerization
  • Disulfides
  • Dose-Response Relationship, Drug
  • Electrophoresis, Polyacrylamide Gel
  • Escherichia coli / metabolism*
  • Escherichia coli Proteins
  • HSP40 Heat-Shock Proteins
  • Heat-Shock Proteins / chemistry*
  • Heat-Shock Proteins / metabolism
  • Kinetics
  • Models, Molecular
  • Models, Statistical
  • Molecular Chaperones / chemistry
  • Oxidoreductases / chemistry
  • Protein Conformation
  • Protein Structure, Tertiary
  • Scattering, Radiation
  • Sulfhydryl Compounds / chemistry
  • X-Rays
  • Zinc Fingers


  • Disulfides
  • DnaJ protein, E coli
  • Escherichia coli Proteins
  • HSP40 Heat-Shock Proteins
  • Heat-Shock Proteins
  • Molecular Chaperones
  • Sulfhydryl Compounds
  • Oxidoreductases