State Key Laboratory of Microbial Technology, School of Life Science, Shandong University, Jinan, Shandong, China.
Curr Microbiol. 2010 Sep;61(3):210-6. doi: 10.1007/s00284-010-9598-1. Epub 2010 Feb 5.
The interplay between the yeast prototypical transcriptional activator Gal4p and the inhibitor protein Gal80p determines the transcriptional status of the genes needed for galactose utilization in Saccharomyces cerevisiae. In this study, we showed that deletion of dsg1 coding for the F box protein Dsg1/Mdm30 delayed but did not eliminate growth of yeast on galactose. Correspondingly, the impaired expression of a GAL1-LacZ reporter in the absence of Dsg1 was only apparent during an early stage of induction. The requirement for Dsg1 in induction was abrogated by the absence of Gal80p or partly bypassed by Gal4 derivatives with decreased interaction with Gal80p. A K23R mutation in the DNA-binding domain of Gal4p was also identified to alleviate the induction defect by dsg1 deletion. On the other hand, the overall accumulation of multi-ubiquitylated Gal4p was not affected by the absence of dsg1 and the induction defect with deletion of dsg1 was partly rescued by disruption of dnm1, a gene encoding a component of the mitochondria division machinery. Taken together, these results suggest that the Dsg1-mediated efficient transcription process of GAL genes may depend on the interaction status between Gal4p and Gal80p.
酵母原型转录激活因子 Gal4p 和抑制剂蛋白 Gal80p 之间的相互作用决定了酿酒酵母利用半乳糖所需基因的转录状态。在这项研究中，我们表明，编码 F 盒蛋白 Dsg1/Mdm30 的 dsg1 缺失会延迟但不会消除酵母在半乳糖上的生长。相应地，在没有 Dsg1 的情况下，GAL1-LacZ 报告基因的表达受损仅在诱导的早期阶段明显。在没有 Gal80p 的情况下，Dsg1 的缺失会消除对诱导的需求，或者通过与 Gal80p 相互作用减弱的 Gal4 衍生物部分绕过。Gal4p 的 DNA 结合域中的 K23R 突变也被鉴定为可以减轻 dsg1 缺失引起的诱导缺陷。另一方面，多泛素化 Gal4p 的整体积累不受 dsg1 缺失的影响，并且 dsg1 缺失的诱导缺陷部分通过破坏编码线粒体分裂机制组件的 dnm1 基因得到挽救。总之，这些结果表明，Dsg1 介导的 GAL 基因有效转录过程可能依赖于 Gal4p 和 Gal80p 之间的相互作用状态。
