Histone chaperones are a diverse class of proteins that facilitate chromatin assembly. Their ability to stabilize highly abundant histone proteins in the cellular environment prevents non-specific interactions and promotes nucleosome formation, but the various mechanisms for doing so are not well understood. We now focus on the dynamic features of the DAXX histone chaperone that have been elusive from previous structural studies. Using hydrogen/deuterium exchange coupled to mass spectrometry (H/DX-MS), we elucidate the concerted binding-folding of DAXX with histone variants H3.3/H4 and H3.2/H4 and find that high local stability at the variant-specific recognition residues rationalizes its known selectivity for H3.3. We show that the DAXX histone binding domain is largely disordered in solution and that formation of the H3.3/H4/DAXX complex induces folding and dramatic global stabilization of both histone and chaperone. Thus, DAXX uses a novel strategy as a molecular chaperone that paradoxically couples its own folding to substrate recognition and binding. Further, we propose a model for the chromatin assembly reaction it mediates, including a stepwise folding pathway that helps explain the fidelity of DAXX in associating with the H3.3 variant, despite an extensive and nearly identical binding surface on its counterparts, H3.1 and H3.2.
Pubmed ID: 24493739 RIS Download
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Collection of structural data of biological macromolecules. Database of information about 3D structures of large biological molecules, including proteins and nucleic acids. Users can perform queries on data and analyze and visualize results.
View all literature mentionsA a configurable software package for peptide and protein mass spectrometry analyses. It includes the SEQUEST search algorithm to identify separate proteins in complex mixtures, interactive navigation tools to filter and sort protein summaries, customized spectral plots, and chromatograms using the PEPMATCH and PEPMAP tools. This software also has batch processing capabilities to improve throughput by queuing up several files, and custom-build proprietary databases, index databases, and retrieve databases through a public server.
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