DnaK-mediated association of ClpB to protein aggregates. A bichaperone network at the aggregate surface.
Intracellular protein aggregates formed under severe thermal stress can be reactivated by the concerted action of the Hsp70 system and Hsp100 chaperones. We analyzed here the interaction of DnaJ/DnaK and ClpB with protein aggregates. We show that aggregate properties modulate chaperone binding, which in turn determines aggregate reactivation efficiency. ClpB binding strictly depends on previous DnaK association with the aggregate. The affinity of ClpB for the aggregate-DnaK complex is low (K(d)=5-10 microM), indicating a weak interaction. Therefore, formation of the DnaK-ClpB bichaperone network is a three step process. After initial DnaJ binding, the cochaperone drives association of DnaK to aggregates, and in the third step, as shown here, DnaK mediates ClpB interaction with the aggregate surface.
Acebrón
Sergio P
SP
Unidad de Biofísica (CSIC-UPV/EHU), and Departamento de Bioquímica y Biología Molecular (UPV/EHU), Facultad de Ciencia y Tecnología, Universidad del País Vasco, PO Box 644, Bilbao, Spain.
Martín
Ianire
I
del Castillo
Urko
U
Moro
Fernando
F
Muga
Arturo
A
D049071:Endopeptidase Clp; D029968:Escherichia coli Proteins / Q000378:metabolism*; D050956:HSP40 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism*; D006360:Heat-Shock Proteins / Q000378:metabolism*; D018832:Molecular Chaperones / Q000378:metabolism*; D011485:Protein Binding
C494635:DnaJ protein, E coli; D029968:Escherichia coli Proteins; D050956:HSP40 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D049071:Endopeptidase Clp; C063842:dnaK protein, E coli; C069775:ClpB protein, E coli