Stern M, Jensen R, Herskowitz I
J Mol Biol. 1984 Oct 5;178(4):853-68. doi: 10.1016/0022-2836(84)90315-2.
High-frequency mating type interconversion in yeast requires the HO gene, which encodes a site-specific endonuclease that initiates the switching process. We have isolated and analyzed switching-defective mutants. These mutants define five complementation and linkage groups, SWI 1 to SWI 5. We have shown by two assays, Northern hybridization and beta-galactosidase activity in strains containing an HO-lacZ fusion, that mutants defective any SWI gene fail to express the HO gene. In addition, all of the swi mutants exhibit other phenotypes, the most notable being the inviability of double mutants defective in SWI 4 and in either SWI 1, SWI 2 or SWI 3. These results indicate that the SWI genes function in some way as positive regulators of HO expression and have additional cellular roles.
酵母中的高频交配型相互转换需要HO基因，该基因编码一种位点特异性内切核酸酶，它启动转换过程。我们已经分离并分析了转换缺陷型突变体。这些突变体定义了五个互补和连锁群，即SWI 1至SWI 5。我们通过两种测定方法，即Northern杂交和含有HO-lacZ融合体的菌株中的β-半乳糖苷酶活性，表明任何SWI基因缺陷的突变体都无法表达HO基因。此外，所有swi突变体都表现出其他表型，最显著的是SWI 4以及SWI 1、SWI 2或SWI 3中任何一个缺陷的双突变体的 inviability。这些结果表明，SWI基因以某种方式作为HO表达的正调节因子发挥作用，并具有额外的细胞作用。
