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Sequence-specific rates of interaction of target peptides with the molecular chaperones DnaK and DnaJ.
Journal article

Sequence-specific rates of interaction of target peptides with the molecular chaperones DnaK and DnaJ.

  • 1998-12-08
Published in:
  • Biochemistry. - 1998
2-Naphthylamine
Adenosine Triphosphate
Amino Acid Sequence
Bacterial Proteins
Escherichia coli
Escherichia coli Proteins
Fluorescent Dyes
HSP40 Heat-Shock Proteins
HSP70 Heat-Shock Proteins
Heat-Shock Proteins
Ligands
Macromolecular Substances
Molecular Sequence Data
Peptides
Protein Binding
Spectrometry, Fluorescence
English The kinetics of complex formation between nine different fluorescence-labeled peptides (7-22 amino acid residues) and DnaK (Hsp70 homologue of Escherichia coli) in the nucleotide-free R state and in the ATP-liganded T state were measured. R-state DnaK (1 microM) formed high-affinity complexes (Kd = 0.06-2 microM) and bound all peptides (22-50 nM) in slow one- or two-step processes with apparent rate constants for the first phase, varying only by a maximum factor of 30 (kobs1 = 0.003-0.084 s-1 at pH 7.0 and 25 degreesC). In contrast, the rates of complex formation between DnaK-ATP and the same peptides (Kd = 2.2-107 microM) have been found previously to vary by 4 orders of magnitude [one- or two-step processes with kobs1 = 0.001-7.9 s-1; Gisler, S. M., Pierpaoli E. V., and Christen, P. (1998) J. Mol. Biol. 279, 833-840]. The slow and relatively uniform rates of peptide binding to the R state might be determined by the fraction of time during which the alpha-helical lid above the peptide-binding site is open. The faster and widely divergent rates of binding to the open T state might reflect sequence-specific conformational rearrangements in the peptide-binding site and perhaps of the peptide itself. The different rates of association with DnaK-ATP suggest a kinetic partitioning of target sequences in which only slowly interacting segments of polypeptides are channeled into the chaperone cycle.
Language
  • English
Open access status
closed
Identifiers
Persistent URL
https://sonar.ch/global/documents/237864
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