Abstract
Saccharomyces cerevisiae (budding yeast) and Schizosaccharomyces pombe (fission yeast) are two of the most recognised and well-studied model systems for epigenetic regulation and the inheritance of chromatin states. Their silent loci serve as a proxy for heterochromatic chromatin in higher eukaryotes, and as such both species have provided a wealth of information on the mechanisms behind the establishment and maintenance of epigenetic states, not only in yeast, but in higher eukaryotes. This review focuses specifically on the role of histone modifications in governing telomeric silencing in S. cerevisiae and centromeric silencing in S. pombe as examples of genetic loci that exemplify epigenetic inheritance. We discuss the recent advancements that for the first time provide a mechanistic understanding of how heterochromatin, dictated by histone modifications specifically, is preserved during S-phase. We also discuss the current state of our understanding of yeast nucleosome dynamics during DNA replication, an essential component in delineating the contribution of histone modifications to epigenetic inheritance.
Highlights
The term epigenetics has invoked much controversy since it was coined by Conrad Waddington in 1942 [1] and despite our best efforts, a working definition of epigenetics varies widely [2]
In the last two decades, studies on yeast have shaped much of our current understanding of epigenetic mechanisms, and they are likely to continue to refine that understanding regarding inheritance of epigenetic states
DNA CpG methylation is absent from both budding and fission yeasts, and S. cerevisiae lacks the RNA interference (RNAi) machinery and repressive histone Histone H3 lysine 9 (H3K9) methylation, which are found in fission yeast and many other eukaryotes
Summary
Saccharomyces cerevisiae (budding yeast) and Schizosaccharomyces pombe (fission yeast) are two of the most recognised and well-studied model systems for epigenetic regulation and the inheritance of chromatin states. Their silent loci serve as a proxy for heterochromatic chromatin in higher eukaryotes, and as such both species have provided a wealth of information on the mechanisms behind the establishment and maintenance of epigenetic states, in yeast, but in higher eukaryotes. We discuss the current state of our understanding of yeast nucleosome dynamics during DNA replication, an essential component in delineating the contribution of histone modifications to epigenetic inheritance. Accepted Manuscript Online: 15 March 2019 Version of Record published: 07 May 2019
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