Sch9 regulates ribosome biogenesis via Stb3, Dot6 and Tod6 and the histone deacetylase complex RPD3L (mRNA-Seq data). Saccharomyces cerevisiae

TORC1 is a structurally and functionally conserved multiprotein complex that regulates many aspects of eukaryote growth including the synthesis and assembly of ribosomes. The protein kinase activity of this complex is responsive to environmental cues and is potently inhibited by the natural product macrolide rapamycin. Insights into how TORC1 regulates growth have been provided with the recent identification of the rapamycin-sensitive phosphoproteome in yeast. Building on these data, we show here that Sch9, an AGC family kinase and direct substrate of TORC1, promotes ribosome biogenesis (ribi) and ribosomal protein (RP) gene expression via direct inhibitory phosphorylation of three transcription repressors, Stb3, Dot6 and Tod6. Dephosphorylation of these factors allows them to recruit the RPD3L histone deactelyase complex to ribi/RP gene promoters. Since rRNA and tRNA transcription are also under its control, Sch9 appears to be well positioned to coordinately regulate transcriptional aspects of ribosome biogenesis. Overall design: mRNA-Seq of 8 S. cerevisiae strains treated with either DMSO alone or 1NM-PP1, a small molecule inhibitor for analog-sensitive kinases such as sch9-as.

雷帕霉素靶蛋白复合物1（TORC1）是一种在结构与功能上均保守的多蛋白复合物，可调控真核生物生长的诸多方面，包括核糖体的合成与组装。该复合物的蛋白激酶活性可响应环境信号，并可被天然大环内酯类产物雷帕霉素强效抑制。近期针对酵母中雷帕霉素敏感磷酸化蛋白质组的鉴定工作，为解析TORC1调控细胞生长的分子机制提供了重要见解。基于上述数据，本研究证实，作为AGC家族激酶及TORC1直接底物的Sch9，可通过对三种转录抑制因子Stb3、Dot6与Tod6实施直接抑制性磷酸化，促进核糖体生物发生（ribi）及核糖体蛋白（RP）基因的表达。上述转录因子的去磷酸化可使其招募RPD3L组蛋白去乙酰化酶复合物结合至核糖体生物发生/核糖体蛋白基因的启动子区域。鉴于核糖体RNA（rRNA）与转运RNA（tRNA）的转录同样受Sch9调控，该激酶似乎能够精准协同调控核糖体生物发生相关的转录事件。

实验设计：对经二甲基亚砜（DMSO）单独处理，或经针对类似物敏感型激酶（如sch9-as）的小分子抑制剂1NM-PP1处理的8株酿酒酵母（S. cerevisiae）菌株进行mRNA测序（mRNA-Seq）。