title: Small heat shock proteins, ClpB and the DnaK system form a functional triade in reversing protein aggregation.
abstract: Small heat shock proteins (sHsps) can efficiently prevent the aggregation of unfolded proteins in vitro. However, how this in vitro activity translates to function in vivo is poorly understood. We demonstrate that sHsps of Escherichia coli, IbpA and IbpB, co-operate with ClpB and the DnaK system in vitro and in vivo, forming a functional triade of chaperones. IbpA/IbpB and ClpB support independently and co-operatively the DnaK system in reversing protein aggregation. A delta ibpAB delta clpB double mutant exhibits strongly increased protein aggregation at 42 degrees C compared with the single mutants. sHsp and ClpB function become essential for cell viability at 37 degrees C if DnaK levels are reduced. The DnaK requirement for growth is increasingly higher for delta ibpAB, delta clpB, and the double delta ibpAB delta clpB mutant cells, establishing the positions of sHsps and ClpB in this chaperone triade.
authors: ZMBH, Universität Heidelberg, Im Neuenheimer Feld 282, Heidelberg D-69120, Germany. a.mogk@zmbh.uni-heidelberg.de
authors: Axel
authors: A
authors: Mogk
authors: Elke
authors: E
authors: Deuerling
authors: Sonja
authors: S
authors: Vorderwülbecke
authors: Elizabeth
authors: E
authors: Vierling
authors: Bernd
authors: B
authors: Bukau
mesh_terms: D049071:Endopeptidase Clp; D029968:Escherichia coli Proteins / Q000378:metabolism*; D018840:HSP70 Heat-Shock Proteins / Q000378:metabolism*; D006360:Heat-Shock Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018832:Molecular Chaperones / Q000378:metabolism; D011485:Protein Binding; D017510:Protein Folding
chemical_list: D029968:Escherichia coli 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