Gene silencing by the SIR (Silent Information Region) family of proteins in S. cerevisiae has 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 in S.cerevisiae was 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.

酿酒酵母中SIR（沉默信息区）蛋白家族的基因沉默已得到广泛研究，并已成为我们对基因阻抑及其与组蛋白脱乙酰化和染色质结构联系的一般理解的基础范例。近年来，我们对酿酒酵母基因阻抑的其他机制的了解明显进步了。在这篇综述中，我们重点研究由各种组蛋白脱乙酰基酶（HDAC）和组蛋白甲基转移酶（HMT）执行的Sir依赖性基因抑制机制。我们关注由这些酶调节的基因及其已知的作用机理。我们描述了HDAC和HMT之间的合作和冗余，以及它们通过非编码RNA或非组蛋白底物参与基因阻抑。我们还提出了由这些酶产生的染色质结构的表观遗传传递模型，并在其他生物的基因抑制现象的背景下讨论了这些模型。这些措施包括对HMT施加的表观遗传标记的回收或对具有HDAC的复合物的回收。