The program for processing newly synthesized histones H3.1 and H4

• DOI: 10.1038/nsmb.1911
• Publication Date: 2010-10-17T17:41:46Z
• Authors: Eric I Campos; Jeffrey Fillingham; Guohong Li; Haiyan Zheng; Philipp Voigt; Wei-Hung W Kuo; Harshika Seepany; Zhonghua Gao; Loren A Day; Jack F Greenblatt; Danny Reinberg
• Keywords: 0301 basic medicine; Cytoplasm; Models, Genetic; Active Transport, Cell Nucleus; Nuclear Proteins; Acetylation; Cell Cycle Proteins; Saccharomyces cerevisiae; Karyopherins; Autoantigens; Article; Cell Line; Epigenesis, Genetic; Histones; 03 medical and health sciences; Humans; Histone Chaperones; RNA Interference; Dimerization; Protein Processing, Post-Translational; Histone Acetyltransferases

The mechanism by which newly synthesized histones are imported into the nucleus and deposited onto replicating chromatin alongside segregating nucleosomal counterparts is poorly understood, yet this program is expected to bear on the putative epigenetic nature of histone post-translational modifications. To define the events by which naive pre-deposition histones are imported into the nucleus, we biochemically purified and characterized the full gamut of histone H3.1-containing complexes from human cytoplasmic fractions and identified their associated histone post-translational modifications. Through reconstitution assays, biophysical analyses and live cell manipulations, we describe in detail this series of events, namely the assembly of H3-H4 dimers, the acetylation of histones by the HAT1 holoenzyme and the transfer of histones between chaperones that culminates with their karyopherin-mediated nuclear import. We further demonstrate the high degree of conservation for this pathway between higher and lower eukaryotes.