The role of the DIF motif of the DnaJ (Hsp40) co-chaperone in the regulation of the DnaK (Hsp70) chaperone cycle

J Biol Chem. 2006 May 5;281(18):12436-44. doi: 10.1074/jbc.M511192200. Epub 2006 Mar 13.

Abstract

To perform effectively as a molecular chaperone, DnaK (Hsp70) necessitates the assistance of its DnaJ (Hsp40) co-chaperone partner, which efficiently stimulates its intrinsically weak ATPase activity and facilitates its interaction with polypeptide substrates. In this study, we address the function of the conserved glycine- and phenylalanine-rich (G/F-rich) region of the Escherichia coli DnaJ in the DnaK chaperone cycle. We show that the G/F-rich region is critical for DnaJ co-chaperone functions in vivo and that despite a significant degree of sequence conservation among the G/F-rich regions of Hsp40 homologs from bacteria, yeast, or humans, functional complementation in the context of the E. coli DnaJ is limited. Furthermore, we found that the deletion of the whole G/F-rich region is mirrored by mutations in the conserved Asp-Ile/Val-Phe (DIF) motif contained in this region. Further genetic and biochemical analyses revealed that this amino acid triplet plays a critical role in regulation of the DnaK chaperone cycle, possibly by modulating a crucial step subsequent to DnaK-mediated ATP hydrolysis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Triphosphate / chemistry
  • Amino Acid Motifs
  • Amino Acid Sequence
  • Animals
  • Conserved Sequence
  • Escherichia coli / metabolism
  • Escherichia coli Proteins / chemistry*
  • Escherichia coli Proteins / metabolism
  • Glycine / chemistry
  • HSP40 Heat-Shock Proteins / chemistry*
  • HSP40 Heat-Shock Proteins / metabolism
  • HSP70 Heat-Shock Proteins / chemistry*
  • HSP70 Heat-Shock Proteins / metabolism
  • Humans
  • Hydrolysis
  • Molecular Chaperones / chemistry
  • Molecular Sequence Data
  • Phenylalanine / chemistry

Substances

  • Escherichia coli Proteins
  • HSP40 Heat-Shock Proteins
  • HSP70 Heat-Shock Proteins
  • Molecular Chaperones
  • Phenylalanine
  • Adenosine Triphosphate
  • dnaK protein, E coli
  • Glycine