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Plant Cell. 2017 Jul;29(7):1773-1793. doi: 10.1105/tpc.16.00877. Epub 2017 Jul 6.

Arabidopsis ATRX Modulates H3.3 Occupancy and Fine-Tunes Gene Expression.

Author information

1
GReD, Université Clermont Auvergne, CNRS, INSERM, 63001 Clermont-Ferrand, France.
2
The Sainsbury Laboratory, University of Cambridge, Cambridge CB2 1LR, United Kingdom.
3
Department of Biological and Medical Sciences, Oxford Brookes University, Oxford OX3 0BP, United Kingdom.
4
Department of Functional Genomics and Cancer, Institut de Génétique et de Biologie Moléculaire et Cellulaire, CNRS/INSERM/ULP, 67404 Illkirch, France.
5
Institute of Plant Sciences Paris Saclay IPS2, CNRS, INRA, Université Paris-Sud, Université Evry, Université Paris-Saclay, 91405 Orsay, France.
6
Division of Biological and Environmental Sciences and Engineering, King Abdullah University of Science and Technology, Thuwal, 23955-6900, Kingdom of Saudi Arabia.
7
GReD, Université Clermont Auvergne, CNRS, INSERM, 63001 Clermont-Ferrand, France aline.probst@uca.fr.

Abstract

Histones are essential components of the nucleosome, the major chromatin subunit that structures linear DNA molecules and regulates access of other proteins to DNA. Specific histone chaperone complexes control the correct deposition of canonical histones and their variants to modulate nucleosome structure and stability. In this study, we characterize the Arabidopsis thaliana Alpha Thalassemia-mental Retardation X-linked (ATRX) ortholog and show that ATRX is involved in histone H3 deposition. Arabidopsis ATRX mutant alleles are viable, but show developmental defects and reduced fertility. Their combination with mutants of the histone H3.3 chaperone HIRA (Histone Regulator A) results in impaired plant survival, suggesting that HIRA and ATRX function in complementary histone deposition pathways. Indeed, ATRX loss of function alters cellular histone H3.3 pools and in consequence modulates the H3.1/H3.3 balance in the cell. H3.3 levels are affected especially at genes characterized by elevated H3.3 occupancy, including the 45S ribosomal DNA (45S rDNA) loci, where loss of ATRX results in altered expression of specific 45S rDNA sequence variants. At the genome-wide scale, our data indicate that ATRX modifies gene expression concomitantly to H3.3 deposition at a set of genes characterized both by elevated H3.3 occupancy and high expression. Together, our results show that ATRX is involved in H3.3 deposition and emphasize the role of histone chaperones in adjusting genome expression.

PMID:
28684426
PMCID:
PMC5559740
DOI:
10.1105/tpc.16.00877
[Indexed for MEDLINE]
Free PMC Article

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