PMID:12654915
| Citation |
Han, W and Christen, P (2003) Mechanism of the targeting action of DnaJ in the DnaK molecular chaperone system. J. Biol. Chem. 278:19038-43 |
|---|---|
| Abstract |
In the DnaK (Hsp70) molecular chaperone system of Escherichia coli, the substrate polypeptide is fed into the chaperone cycle by association with the fast-binding, ATP-liganded form of the DnaK. The substrate binding properties of DnaK are controlled by its two cochaperones DnaJ (Hsp40) and GrpE. DnaJ stimulates the hydrolysis of DnaK-bound ATP, and GrpE accelerates ADP/ATP exchange. DnaJ has been described as targeting the substrate to DnaK, a concept that has remained rather obscure. Based on binding experiments with peptides and polypeptides we propose here a novel mechanism for the targeting action of DnaJ: ATP.DnaK and DnaJ with its substrate-binding domain bind to different segments of one and the same polypeptide chain forming (ATP.DnaK)m.substrate.DnaJn complexes; in these ternary complexes efficient cis-interaction of the J-domain of DnaJ with DnaK is favored by their propinquity and triggers the hydrolysis of DnaK-bound ATP, converting DnaK to its ADP-liganded high affinity state and thus locking it onto the substrate polypeptide. |
| Links |
PubMed Online version:10.1074/jbc.M300756200 |
| Keywords |
Adenosine Diphosphate/metabolism; Adenosine Triphosphatases/metabolism; Adenosine Triphosphate/metabolism; Bacterial Proteins/pharmacology; Binding, Competitive; Chromatography, High Pressure Liquid; Escherichia coli; Escherichia coli Proteins; HSP40 Heat-Shock Proteins; HSP70 Heat-Shock Proteins/metabolism; Heat-Shock Proteins/metabolism; Heat-Shock Proteins/pharmacology; Hydrolysis; Luciferases/chemistry; Luciferases/pharmacology; Peptide Fragments/metabolism; Protein Binding; Protein Denaturation; Protein Folding; Thiosulfate Sulfurtransferase/chemistry; Thiosulfate Sulfurtransferase/pharmacology |
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