The histone chaperones ASF1 and HIRA are required for telomere length and 45S rDNA copy number homeostasis

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Authors

MACHELOVÁ Adéla NEŠPOR DADEJOVÁ Martina FRANEK Michal MOUGEOT Guillaume SIMON Lauriane LE GOFF Samuel DUC Celine BASSLER Jasmin DEMKO Martin SCHWARZEROVA Jana DESSET Sophie PROBST Aline V DVOŘÁČKOVÁ Martina

Year of publication 2024
Type Article in Periodical
Magazine / Source Plant Journal
MU Faculty or unit

Central European Institute of Technology

Citation
web https://onlinelibrary.wiley.com/doi/10.1111/tpj.17041?af=R
Doi http://dx.doi.org/10.1111/tpj.17041
Keywords chromatin; telomeres; histone chaperones; ASF1; HIRA; 45S rDNA; Arabidopsis thaliana
Description Genome stability is significantly influenced by the precise coordination of chromatin complexes that facilitate the loading and eviction of histones from chromatin during replication, transcription, and DNA repair processes. In this study, we investigate the role of the Arabidopsis H3 histone chaperones ANTI-SILENCING FUNCTION 1 (ASF1) and HISTONE REGULATOR A (HIRA) in the maintenance of telomeres and 45S rDNA loci, genomic sites that are particularly susceptible to changes in the chromatin structure. We find that both ASF1 and HIRA are essential for telomere length regulation, as telomeres are significantly shorter in asf1a1b and hira mutants. However, these shorter telomeres remain localized around the nucleolus and exhibit a comparable relative H3 occupancy to the wild type. In addition to regulating telomere length, ASF1 and HIRA contribute to silencing 45S rRNA genes and affect their copy number. Besides, ASF1 supports global heterochromatin maintenance. Our findings also indicate that ASF1 transiently binds to the TELOMERE REPEAT BINDING 1 protein and the N terminus of telomerase in vivo, suggesting a physical link between the ASF1 histone chaperone and the telomere maintenance machinery.
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