title: D-Peptides as inhibitors of the DnaK/DnaJ/GrpE chaperone system.
abstract: DnaK, a Hsp70 homolog of Escherichia coli, together with its co-chaperones DnaJ and GrpE protects denatured proteins from aggregation and promotes their refolding by an ATP-consuming mechanism. DnaJ not only stimulates the gamma-phosphate cleavage of DnaK-bound ATP but also binds polypeptide substrates on its own. Unfolded polypeptides, such as denatured luciferase, thus form ternary complexes with DnaJ and DnaK. A previous study has shown that d-peptides compete with l-peptides for the same binding site in DnaJ but do not bind to DnaK (Feifel, B., Schönfeld, H.-J., and Christen, P. (1998) J. Biol. Chem. 273, 11999-12002). Here we report that d-peptides efficiently inhibit the refolding of denatured luciferase by the DnaK/DnaJ/GrpE chaperone system (EC50 = 1-2 microM). The inhibition of the chaperone action is due to the binding of d-peptide to DnaJ (Kd = 1-2 microM), which seems to preclude DnaJ from forming ternary (ATP.DnaK)m.substrate.DnaJn complexes. Apparently, simultaneous binding of DnaJ and DnaK to one and the same target polypeptide is essential for effective chaperone action.
authors.affiliation: Biochemisches Institut der Universität Zürich, Winterthurerstrasse 190, CH-8057, Zürich, Switzerland.
authors.forename: Pius
authors.initials: P
authors.lastname: Bischofberger
authors.forename: Wanjiang
authors.initials: W
authors.lastname: Han
authors.forename: Bastian
authors.initials: B
authors.lastname: Feifel
authors.forename: Hans-Joachim
authors.initials: HJ
authors.lastname: Schönfeld
authors.forename: Philipp
authors.initials: P
authors.lastname: Christen
mesh_terms: D000251:Adenosine Triphosphatases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D001426:Bacterial Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism / Q000494:pharmacology; D001665:Binding Sites; D001667:Binding, Competitive; D004926:Escherichia coli / Q000737:chemistry; D029968:Escherichia coli Proteins; D050956:HSP40 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism / Q000494:pharmacology; D006360:Heat-Shock Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism / Q000494:pharmacology; D007700:Kinetics; D008156:Luciferases / Q000737:chemistry; D010446:Peptide Fragments / Q000378:metabolism / Q000494:pharmacology*; D011489:Protein Denaturation; D017510:Protein Folding; D013884:Thiosulfate Sulfurtransferase / Q000737:chemistry*
chemical_list: D001426:Bacterial Proteins; C494635:DnaJ protein, E coli; D029968:Escherichia coli Proteins; C068113:GrpE protein, Bacteria; C489400:GrpE protein, E coli; D050956:HSP40 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D010446:Peptide Fragments; D000255:Adenosine Triphosphate; D008156:Luciferases; D013884:Thiosulfate Sulfurtransferase; D000251:Adenosine Triphosphatases; C063842:dnaK protein, E coli