TONSOKU is required for the maintenance of repressive chromatin modifications in Arabidopsis

• Published in: Cell reports (Cambridge) 2023-07, Vol.42 (7), p.112738-112738, Article 112738
• Main Authors: Wang, Lin, Xue, Mande, Zhang, Huairen, Ma, Lijun, Jiang, Danhua
• Format: Article
• Language: English
• Subjects: Animals; Arabidopsis - genetics; Arabidopsis - metabolism; chromatin; Chromatin - metabolism; CP: Molecular biology; CP: Plants; DNA Methylation; DNA Replication; epigenetic inheritance; H2A.W; H3K27 methylation; H3K9 methylation; Histones - metabolism; Polycomb-Group Proteins - metabolism; replication
• ISSN: 2211-1247; 2211-1247
• DOI: 10.1016/j.celrep.2023.112738

The stability of eukaryotic genomes relies on the faithful transmission of DNA sequences and the maintenance of chromatin states through DNA replication. Plant TONSOKU (TSK) and its animal ortholog TONSOKU-like (TONSL) act as readers for newly synthesized histones and preserve DNA integrity via facilitating DNA repair at post-replicative chromatin. However, whether TSK/TONSL regulate the maintenance of chromatin states remains elusive. Here, we show that TSK is dispensable for global histone and nucleosome accumulation but necessary for maintaining repressive chromatin modifications, including H3K9me2, H2A.W, H3K27me3, and DNA methylation. TSK physically interacts with H3K9 methyltransferases and Polycomb proteins. Moreover, TSK mutation strongly enhances defects in Polycomb pathway mutants. TSK is intended to only associate with nascent chromatin until it starts to mature. We propose that TSK ensures the preservation of chromatin states by supporting the recruitment of chromatin modifiers to post-replicative chromatin in a critical short window of time following DNA replication. [Display omitted] •TSK is dispensable for global histone and nucleosome accumulation•TSK contributes to the maintenance of repressive chromatin modifications•TSK associates with the H3K9 methyltransferases SUVH5 and SUVH6•TSK physically and genetically interacts with PcG proteins Plant TONSOKU (TSK) and its animal ortholog TONSOKU-like (TONSL) have been found to aid in DNA damage repair during DNA replication. Here, Wang et al. show that TSK also participates in the maintenance of chromatin modifications, suggesting multiple functions of TSK/TONSL in safeguarding both DNA integrity and chromatin states.