Author:
Kitada Tasuku,Kuryan Benjamin G.,Tran Nancy Nga Huynh,Song Chunying,Xue Yong,Carey Michael,Grunstein Michael
Abstract
Yeast contains heterochromatin at telomeres and the silent mating-type loci (HML/HMR). Genes positioned within the telomeric heterochromatin of Saccharomyces cerevisiae switch stochastically between epigenetically bistable ON and OFF expression states. Important aspects of the mechanism of variegated gene expression, including the chromatin structure of the natural ON state and the mechanism by which it is maintained, are unknown. To address this issue, we developed approaches to select cells in the ON and OFF states. We found by chromatin immunoprecipitation (ChIP) that natural ON telomeres are associated with Rap1 binding and, surprisingly, also contain known characteristics of OFF telomeres, including significant amounts of Sir3 and H4K16 deacetylated nucleosomes. Moreover, we found that H3K79 methylation (H3K79me), H3K4me, and H3K36me, which are depleted from OFF telomeres, are enriched at ON telomeres. We demonstrate in vitro that H3K79me, but not H3K4me or H3K36me, disrupts transcriptional silencing. Importantly, H3K79me does not significantly reduce Sir complex binding in vivo or in vitro. Finally, we show that maintenance of H3K79me at ON telomeres is dependent on transcription. Therefore, although Sir proteins are required for silencing, we propose that epigenetic variegation of telomeric gene expression is due to the bistable enrichment/depletion of H3K79me and not the fluctuation in the amount of Sir protein binding to nucleosomes.
Publisher
Cold Spring Harbor Laboratory
Subject
Developmental Biology,Genetics
Reference85 articles.
1. Interplay of Chromatin Modifiers on a Short Basic Patch of Histone H4 Tail Defines the Boundary of Telomeric Heterochromatin
2. Structural Basis of Silencing: Sir3 BAH Domain in Complex with a Nucleosome at 3.0 Å Resolution
3. [10] 5-Fluoroorotic acid as a selective agent in yeast molecular genetics
4. High-throughput real-time quantitative reverse transcription PCR;Curr Protoc Mol Biol,2006
5. Two DNA-binding factors recognize specific sequences at silencers, upstream activating sequences, autonomously replicating sequences, and telomeres in Saccharomyces cerevisiae;Mol Cell Biol,1988
Cited by
56 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献