Molecular Plant
Volume 11, Issue 8, 6 August 2018, Pages 1038-1052
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Research Article
LHP1 Interacts with ATRX through Plant-Specific Domains at Specific Loci Targeted by PRC2

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Abstract

Heterochromatin Protein 1 (HP1) is a major regulator of chromatin structure and function. In animals, the network of proteins interacting with HP1 is mainly associated with constitutive heterochromatin marked by H3K9me3. HP1 physically interacts with the putative ortholog of the SNF2 chromatin remodeler ATRX, which controls deposition of histone variant H3.3 in mammals. In this study, we show that the Arabidopsis thaliana ortholog of ATRX participates in H3.3 deposition and possesses specific conserved domains in plants. We found that plant Like HP1 (LHP1) protein interacts with ATRX through domains that evolved specifically in land plant ancestors. Loss of ATRX function in Arabidopsis affects the expression of a limited subset of genes controlled by PRC2 (POLYCOMB REPRESSIVE COMPLEX 2), including the flowering time regulator FLC. The function of ATRX in regulation of flowering time requires novel LHP1-interacting domain and ATPase activity of the ATRX SNF2 helicase domain. Taken together, these results suggest that distinct evolutionary pathways led to the interaction between ATRX and HP1 in mammals and its counterpart LHP1 in plants, resulting in distinct modes of transcriptional regulation.

Key words

ATRX
LHP1
H3 variants
Chromatin
Histone
Evolution

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Published by the Molecular Plant Shanghai Editorial Office in association with Cell Press, an imprint of Elsevier Inc., on behalf of CSPB and IPPE, SIBS, CAS.