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The histone chaperone complex HIR maintains nucleosome occupancy and counterbalances impaired histone deposition in CAF ‐1 complex mutants
Author(s) -
Duc Céline,
Benoit Matthias,
Le Goff Samuel,
Simon Lauriane,
Poulet Axel,
Cotterell Sylviane,
Tatout Christophe,
Probst Aline V.
Publication year - 2015
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.12758
Subject(s) - nucleosome , chromatin , histone , microbiology and biotechnology , biology , histone code , epigenetics , chaperone (clinical) , mutant , genetics , histone h2a , chromatin immunoprecipitation , histone h3 , gene , gene expression , promoter , pathology , medicine
Summary Chromatin organization is essential for coordinated gene expression, genome stability, and inheritance of epigenetic information. The main components involved in chromatin assembly are specific complexes such as Chromatin Assembly Factor 1 ( CAF ‐1) and Histone Regulator ( HIR ), which deposit histones in a DNA synthesis‐dependent or ‐independent manner, respectively. Here, we characterize the role of the plant orthologs Histone Regulator A ( HIRA ), Ubinuclein ( UBN ) and Calcineurin Binding protein 1 ( CABIN 1), which constitute the HIR complex. Arabidopsis loss‐of‐function mutants for the various subunits of the complex are viable, but hira mutants show reduced fertility. We show that loss of HIRA reduces extractable histone H3 protein levels and decreases nucleosome occupancy at both actively transcribed genes and heterochromatic regions. Concomitantly, HIRA contributes to maintenance of silencing of pericentromeric repeats and certain transposons. A genetic analysis based on crosses between mutants deficient in subunits of the CAF ‐1 and HIR complexes showed that simultaneous loss of both the CAF ‐1 and HIR histone H3 chaperone complexes severely affects plant survival, growth and reproductive development. Our results suggest that HIRA partially rescues impaired histone deposition in fas mutants to preserve nucleosome occupancy, implying plasticity in histone variant interaction and deposition.