Nasmyth K, Stillman D, Kipling D
Cell. 1987 Feb 27;48(4):579-87. doi: 10.1016/0092-8674(87)90236-4.
The HO gene, which encodes an endonuclease responsible for initiating mating type switching in yeast, is transcribed at START during the cell cycle of mother cells but not at all during the cell cycle of daughter cells. At least six genes, called SWI1-6, are necessary for HO transcription. We describe the isolation and characterization of mutations in two new genes called SDI1 and SDI2, which partially suppress the requirement for SWI5 and which cause daughter cells to express HO. The analysis of mating type switching in swi5- sdi1- and SWI5+ sdi1- strains suggests that the mother cell specificity of HO transcription is due exclusively to the selective action of SWI5 in mother cells. SDI1 encodes (or regulates) a repressor protein that binds to the HO promoter and prevents HO transcription in daughter cells by causing HO to be fully SWI5 dependent.
HO基因编码一种核酸内切酶，负责启动酵母中的交配型转换，在母细胞的细胞周期中于START时转录，但在子细胞的细胞周期中完全不转录。至少有六个基因，称为SWI1 - 6，是HO转录所必需的。我们描述了两个新基因SDI1和SDI2中突变的分离和表征，这两个基因部分抑制了对SWI5的需求，并导致子细胞表达HO。对swi5 - sdi1 - 和SWI5 + sdi1 - 菌株中交配型转换的分析表明，HO转录的母细胞特异性完全归因于SWI5在母细胞中的选择性作用。SDI1编码（或调节）一种阻遏蛋白，该蛋白与HO启动子结合，并通过使HO完全依赖SWI5来阻止子细胞中的HO转录。
