Recruitment of Rpd3 to the telomere depends on the protein arginine methyltransferase Hmt1

PLoS One. 2012;7(8):e44656. doi: 10.1371/journal.pone.0044656. Epub 2012 Aug 31.

Abstract

In the yeast Saccharomyces cerevisiae, the establishment and maintenance of silent chromatin at the telomere requires a delicate balance between opposing activities of histone modifying enzymes. Previously, we demonstrated that the protein arginine methyltransferase Hmt1 plays a role in the formation of yeast silent chromatin. To better understand the nature of the Hmt1 interactions that contribute to this phenomenon, we carried out a systematic reverse genetic screen using a null allele of HMT1 and the synthetic genetic array (SGA) methodology. This screen revealed interactions between HMT1 and genes encoding components of the histone deacetylase complex Rpd3L (large). A double mutant carrying both RPD3 and HMT1 deletions display increased telomeric silencing and Sir2 occupancy at the telomeric boundary regions, when comparing to a single mutant carrying Hmt1-deletion only. However, the dual rpd3/hmt1-null mutant behaves like the rpd3-null single mutant with respect to silencing behavior, indicating that RPD3 is epistatic to HMT1. Mutants lacking either Hmt1 or its catalytic activity display an increase in the recruitment of histone deacetylase Rpd3 to the telomeric boundary regions. Moreover, in such loss-of-function mutants the levels of acetylated H4K5, which is a substrate of Rpd3, are altered at the telomeric boundary regions. In contrast, the level of acetylated H4K16, a target of the histone deacetylase Sir2, was increased in these regions. Interestingly, mutants lacking either Rpd3 or Sir2 display various levels of reduction in dimethylated H4R3 at these telomeric boundary regions. Together, these data provide insight into the mechanism whereby Hmt1 promotes the proper establishment and maintenance of silent chromatin at the telomeres.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetylation
  • Chromatin Immunoprecipitation
  • Epistasis, Genetic
  • Gene Silencing
  • Genes, Synthetic / genetics
  • Genetic Testing
  • Genome, Fungal / genetics
  • Histone Deacetylases / genetics
  • Histone Deacetylases / metabolism*
  • Histones / metabolism
  • Methylation
  • Mutation / genetics
  • Protein Binding
  • Protein Subunits / metabolism
  • Protein-Arginine N-Methyltransferases / genetics
  • Protein-Arginine N-Methyltransferases / metabolism*
  • Repressor Proteins / genetics
  • Repressor Proteins / metabolism*
  • Saccharomyces cerevisiae / enzymology*
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism*
  • Silent Information Regulator Proteins, Saccharomyces cerevisiae / metabolism
  • Sirtuin 2 / metabolism
  • Telomere / metabolism*

Substances

  • Histones
  • Protein Subunits
  • Repressor Proteins
  • Saccharomyces cerevisiae Proteins
  • Silent Information Regulator Proteins, Saccharomyces cerevisiae
  • HMT1 protein, S cerevisiae
  • Protein-Arginine N-Methyltransferases
  • RPD3 protein, S cerevisiae
  • SIR2 protein, S cerevisiae
  • Sirtuin 2
  • Histone Deacetylases

Grants and funding

This work was supported by a Scientist Development grant (0830279N) from the American Heart Association, to MCY. The publication costs of this article were supported by the Julian Park Fund, College of Arts and Sciences, University at Buffalo. The funders had no role in study design, data collection, data interpretation, or the decision to prepare and publish of the manuscript.