Hsp90 and p23 Molecular Chaperones Control Chromatin Architecture by Maintaining the Functional Pool of the RSC
Frank J Echtenkamp1, Zlata Gvozdenov2, Nicholas L Adkins3
1Department of Cell and Developmental Biology, University of Illinois, Urbana-Champaign, 601 S. Goodwin Avenue, Urbana, IL 61801, USA.
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.
Related Concept Videos
Nucleosome Remodeling
Nucleosome remodeling complex
Eukaryotic cells have specialized enzymes called ATP-dependent nucleosome remodeling enzymes. These enzymes...
Chromatin Structure Regulates pre-mRNA Processing
The chromatin structure, especially...
Spreading of Chromatin Modifications
Writers
The writer...
Heterochromatin
Constitutive heterochromatin: It is a highly compact region of chromatin that is mostly concentrated in the centromere and telomere. Unlike euchromatin, the amino acid at...
Chromatin Modification in iPS Cells
Compact chromatin makes reprogramming difficult. Enzymes, such as histone demethylases and acetyltransferases, are often added during reprogramming to loosen the chromatin, making the DNA more accessible to transcription factors. Molecules that inhibit histone...
Regulation of Nuclear Protein Sorting


