Histone H3 N-terminal acetylation sites especially K14 are important for rDNA silencing and aging

Heng-Hao Xu,Yong Xue,Trent Su

doi:10.1038/srep21900

Heng-Hao Xu, Yong Xue + Show 1 more

Open Access

https://doi.org/10.1038/srep21900

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Abstract

Histone variants and histone modifications are essential components in the establishment and maintenance of the repressed status of heterochromatin. Among these histone variants and modifications, acetylation at histone H4K16 is uniquely important for the maintenance of silencing at telomere and mating type loci but not at the ribosomal DNA locus. Here we show that mutations at H3 N-terminal acetylation site K14 specifically disrupt rDNA silencing. However, the mutant ion at H3K14R doesn’t affect the recruitment of Pol II repressor RENT (regulator of nucleolar silencing and telophase exit) complex at the rDNA region. Instead, the CAF-1(chromatin assembly factor I) subunit Cac2 level decreased in the H3K14R mutant. Further experiments revealed that the single mutation at H3K14 and multi-site mutations at H3 N-terminus including K14 also delayed replication-depend nucleosome assembly and advanced replicative life span. In conclusion, our data suggest that histone H3 N-terminal acetylation sites especially at K14 are important for rDNA silencing and aging.

Highlights

We investigated the role of histone H3 N terminal acetylation in rDNA silencing by measuring the expression of silencing reporter gene MET15, which was integrated into the RDN1 locus
Histone H3K14 acetylation is uniquely important for rDNA silencing
To determine which lysine residues are primarily involved and/or whether their function are redundantly involved in RDN1 silencing, we used RT-PCR to examine the expression of MET15 reporters at the RDN1 locus in nested H3 N terminal single and multiple amino acid substitutions at five H3 acetylation sites

Summary

Introduction

We investigated the role of histone H3 N terminal acetylation in rDNA silencing by measuring the expression of silencing reporter gene MET15, which was integrated into the RDN1 locus. We found that among H3 N terminal acetylation residues (K9, K14, K18, K23, and K27), K14 is uniquely important for rDNA silencing. The LRS mutation H3K14R does not affect RENT complex recruitment. The recruitment of chromatin assembly factor (CAF-1) subunit Cac[2] is decreased in H3K14R mutant. Further experiments revealed that H3K14 acetylation regulates replication-depend nucleosome assembly and replicative aging. Our data indicate that histone H3 N-terminal acetylation sites especially at K14 are important for rDNA silencing and aging, possibly through replication-dependent nucleosome assembly factor CAF-1

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