Histone H1 protects telomeric repeats from H3K27me3 invasion in Arabidopsis

Gianluca Teano (1) , Lorenzo Concia (1) , Léopold Carron (2) , Léa Wolff (1) , Kateřina Adamusová , Miloslava Fojtová , Michael Bourge , Amira Kramdi , Vincent Colot (1) , Ueli Grossniklaus , Chris Bowler (1) , Célia Baroux , Alessandra Carbone (2) , Aline V. Probst (3) , Petra Procházková Schrumpfová , Jiří Fajkus , Simon Amiard (3) , Stefan Grob , Clara Bourbousse (1) , Fredy Barneche (1)

1 IBENS - Institut de biologie de l'ENS Paris
2 LCQB - Biologie Computationnelle et Quantitative = Laboratory of Computational and Quantitative Biology
3 GReD - Génétique, Reproduction et Développement

Linker histones play a pivotal role in shaping chromatin architecture, notably through their globular H1 (GH1) domain that contacts the nucleosome and linker DNA. Yet, the interplay of H1 with chromatin factors along the epigenome landscape is poorly understood. Here, we report that Arabidopsis H1 favors chromatin compaction and H3K27me3 marking on a majority of Polycomb-targeted protein-coding genes while preventing H3K27me3 accumulation on telomeres and pericentromeric interstitial telomeric repeats (ITRs). These contrasting effects of H1 on H3K27me3 enrichment are associated with long-distance effects on the 3D organization of telomeres and ITRs. Mechanistically, H1 prevents ITRs from being invaded by Telomere Repeat Binding 1 (TRB1), a GH1-containing telomere component with an extra-telomeric function in targeting Polycomb to genes bearing telomeric motifs. We propose that reciprocal DNA binding of H1 and TRB1 to clustered telobox motifs prevents H3K27me3 accumulation on large chromosomal blocks, conferring a sequence-specific role to H1 in epigenome homeostasis.

Domaines: Sciences du Vivant [q-bio]

Gianluca Teano, Lorenzo Concia, Léopold Carron, Léa Wolff, Kateřina Adamusová, et al.. Histone H1 protects telomeric repeats from H3K27me3 invasion in Arabidopsis. 2021. ⟨hal-03099675⟩