Head-to-tail interactions of the coiled-coil domains regulate ClpB cooperation with Hsp70 in protein disaggregation
- Birkbeck College, University of London, United Kingdom
- Zentrum für Molekulare Biologie der Universität Heidelberg, Germany
- Ludwig-Maximilians-University Munich, Germany
- Biochemie-Zentrum der Universität Heidelberg (BZH), Germany
Abstract
The hexameric AAA+ chaperone ClpB reactivates aggregated proteins in cooperation with the Hsp70 system. Essential for disaggregation, the ClpB middle domain (MD) is a coiled-coil propeller that binds Hsp70. Although the ClpB subunit structure is known, positioning of the MD in the hexamer and its mechanism of action are unclear. We obtained electron microscopy (EM) structures of the BAP variant of ClpB that binds the protease ClpP, clearly revealing MD density on the surface of the ClpB ring. Mutant analysis and asymmetric reconstructions show that MDs adopt diverse positions in a single ClpB hexamer. Adjacent, horizontally oriented MDs form head-to-tail contacts and repress ClpB activity by preventing Hsp70 interaction. Tilting of the MD breaks this contact, allowing Hsp70 binding, and releasing the contact in adjacent subunits. Our data suggest a wavelike activation of ClpB subunits around the ring.
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© 2014, Carroni et al.
This article is distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use and redistribution provided that the original author and source are credited.
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Head-to-tail interactions of the coiled-coil domains regulate ClpB cooperation with Hsp70 in protein disaggregation
eLife 3:e02481.
https://doi.org/10.7554/eLife.02481
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