Gene repression inS. cerevisiae-looking beyond Sir-dependent gene silencing

摘要

Gene silencing by theSIR(Silent Information Region) family of proteins inS. cerevisiaehas been extensively studied and has served as a founding paradigm for our general understanding of gene repression and its links to histone deacetylation and chromatin structure. In recent years, our understanding of other mechanisms of gene repression inS.cerevisiaewas significantly advanced. In this review, we focus on such Sir-independent mechanisms of gene repression executed by various Histone Deacetylases (HDACs) and Histone Methyl Transferases (HMTs). We focus on the genes regulated by these enzymes and their known mechanisms of action. We describe the cooperation and redundancy between HDACs and HMTs, and their involvement in gene repression by non-coding RNAs or by their non-histone substrates. We also propose models of epigenetic transmission of the chromatin structures produced by these enzymes and discuss these in the context of gene repression phenomena in other organisms. These include the recycling of the epigenetic marks imposed by HMTs or the recycling of the complexes harboring HDACs.