A protein quality control system, consisting of molecular chaperones and proteases, controls the folding status of proteins and mediates the refolding or degradation of misfolded proteins. Ring-forming AAA+ (ATPase associated with various cellular activities) proteins play crucial roles in both processes by co-operating with either peptidases or chaperone systems. Peptidase-associated AAA+ proteins bind substrates and thread them through their axial channel into the attached proteolytic chambers for degradation. In contrast, the AAA+ protein ClpB evolved independently from an interacting peptidase and co-operates with a cognate Hsp70 (heat-shock protein 70) chaperone system to solubilize and refold aggregated proteins. The activity of this bi-chaperone system is crucial for the survival of bacteria, yeast and plants during severe stress conditions. Hsp70 acts at initial stages of the disaggregation process, enabling ClpB to extract single unfolded polypeptides from the aggregate via a threading activity. Although both classes of AAA+ proteins share a common threading activity, it is apparent that their divergent evolution translates into specific mechanisms, reflecting adaptations to their respective functions. The ClpB-specific M-domain (middle domain) represents such an extra feature that verifies ClpB as the central disaggregase in vivo. M-domains act as regulatory devices to control both ClpB ATPase activity and the Hsp70-dependent binding of aggregated proteins to the ClpB pore, thereby coupling the Hsp70 chaperone activity with the ClpB threading motor to ensure efficient protein disaggregation.
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February 2008
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Conference Article|
January 22 2008
Common and specific mechanisms of AAA+ proteins involved in protein quality control
Axel Mogk;
Axel Mogk
1
1ZMBH (Zentrum fuer Molekulare Biologie Heidelberg), Universität Heidelberg, Im Neuenheimer Feld 282, Heidelberg D-69120, Germany
1Correspondence may be addressed to either of these authors (email bukau@zmbh.uni-heidelberg.de or a.mogk@zmbh.uni-heidelberg.de).
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Tobias Haslberger;
Tobias Haslberger
1ZMBH (Zentrum fuer Molekulare Biologie Heidelberg), Universität Heidelberg, Im Neuenheimer Feld 282, Heidelberg D-69120, Germany
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Peter Tessarz;
Peter Tessarz
1ZMBH (Zentrum fuer Molekulare Biologie Heidelberg), Universität Heidelberg, Im Neuenheimer Feld 282, Heidelberg D-69120, Germany
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Bernd Bukau
Bernd Bukau
1
1ZMBH (Zentrum fuer Molekulare Biologie Heidelberg), Universität Heidelberg, Im Neuenheimer Feld 282, Heidelberg D-69120, Germany
1Correspondence may be addressed to either of these authors (email bukau@zmbh.uni-heidelberg.de or a.mogk@zmbh.uni-heidelberg.de).
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Publisher: Portland Press Ltd
Received:
August 14 2007
Online ISSN: 1470-8752
Print ISSN: 0300-5127
© The Authors Journal compilation © 2008 Biochemical Society
2008
Biochem Soc Trans (2008) 36 (1): 120–125.
Article history
Received:
August 14 2007
Citation
Axel Mogk, Tobias Haslberger, Peter Tessarz, Bernd Bukau; Common and specific mechanisms of AAA+ proteins involved in protein quality control. Biochem Soc Trans 1 February 2008; 36 (1): 120–125. doi: https://doi.org/10.1042/BST0360120
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