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Mol Cell. 2016 Dec 1;64(5):888-899. doi: 10.1016/j.molcel.2016.09.040. Epub 2016 Nov 3.

Hsp90 and p23 Molecular Chaperones Control Chromatin Architecture by Maintaining the Functional Pool of the RSC Chromatin Remodeler.

Author information

1
Department of Cell and Developmental Biology, University of Illinois, Urbana-Champaign, 601 S. Goodwin Avenue, Urbana, IL 61801, USA.
2
Department of Cell and Developmental Biology, University of Illinois, Urbana-Champaign, 601 S. Goodwin Avenue, Urbana, IL 61801, USA; Department Chemie, Technische Universität München, Garching 85748, Germany.
3
Program of Molecular Medicine, University of Massachusetts Medical School, 373 Plantation Street, Worcester, MA 01605, USA.
4
Department of Cell and Developmental Biology, University of Illinois, Urbana-Champaign, 601 S. Goodwin Avenue, Urbana, IL 61801, USA. Electronic address: bfree@illinois.edu.

Abstract

Molecular chaperones govern protein homeostasis, being allied to the beginning (folding) and ending (degradation) of the protein life cycle. Yet, the Hsp90 system primarily associates with native factors, including fully assembled complexes. The significance of these connections is poorly understood. To delineate why Hsp90 and its cochaperone p23 interact with a mature structure, we focused on the RSC chromatin remodeler. Both Hsp90 and p23 triggered the release of RSC from DNA or a nucleosome. Although Hsp90 only freed bound RSC, p23 enhanced nucleosome remodeling prior to discharging the complex. In vivo, RSC mobility and remodeling function were chaperone dependent. Our results suggest Hsp90 and p23 contribute to proteostasis by chaperoning mature factors through energetically unfavorable events, thereby maintaining the cellular pool of active native proteins. In the case of RSC, p23 and Hsp90 promote a dynamic action, allowing a limited number of remodelers to effectively maintain chromatin in a pliable state.

KEYWORDS:

Hsp90; RSC; chromatin remodeling; molecular chaperones; p23; protein dynamics

PMID:
27818141
DOI:
10.1016/j.molcel.2016.09.040
[Indexed for MEDLINE]
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