DAXX adds a de novo H3.3K9me3 deposition pathway to the histone chaperone network.

A multitude of histone chaperones are required to support histones from their biosynthesis until DNA deposition. They cooperate through the formation of histone co-chaperone complexes, but the crosstalk between nucleosome assembly pathways remains enigmatic. Using exploratory interactomics, we define the interplay between human histone H3-H4 chaperones in the histone chaperone network. We identify previously uncharacterized histone-dependent complexes and predict the structure of the ASF1 and SPT2 co-chaperone complex, expanding the role of ASF1 in histone dynamics. We show that DAXX provides a unique functionality to the histone chaperone network, recruiting histone methyltransferases to promote H3K9me3 catalysis on new histone H3.3-H4 prior to deposition onto DNA. Hereby, DAXX provides a molecular mechanism for de novo H3K9me3 deposition and heterochromatin assembly. Collectively, our findings provide a framework for understanding how cells orchestrate histone supply and employ targeted deposition of modified histones to underpin specialized chromatin states.
Competing Interests: Declaration of interests C.M.H. and A.G. are inventors on a patent covering the therapeutic targeting of TONSL for cancer therapy. A.G. is co-founder and chief scientific officer of Ankrin Therapeutics. A.G. is a member of Molecular Cell’s Scientific Advisory Board. A.I. and M.V.-A. are cofounders of EpiQMAx. G.M. is co-founder and member of the board of directors of Twelve Bio and is a member of the Scientific Advisory Board at Ensoma.
(Copyright © 2023 The Author(s). Published by Elsevier Inc. All rights reserved.)