Huber Alexandre, Bodenmiller Bernd, Uotila Aino, Stahl Michael, Wanka Stefanie, Gerrits Bertran, Aebersold Ruedi, Loewith Robbie
Department of Molecular Biology, University of Geneva, Geneva, Switzerland.
Genes Dev. 2009 Aug 15;23(16):1929-43. doi: 10.1101/gad.532109.
The target of rapamycin complex 1 (TORC1) is an essential multiprotein complex conserved from yeast to humans. Under favorable growth conditions, and in the absence of the macrolide rapamycin, TORC1 is active, and influences virtually all aspects of cell growth. Although two direct effectors of yeast TORC1 have been reported (Tap42, a regulator of PP2A phosphatases and Sch9, an AGC family kinase), the signaling pathways that couple TORC1 to its distal effectors were not well understood. To elucidate these pathways we developed and employed a quantitative, label-free mass spectrometry approach. Analyses of the rapamycin-sensitive phosphoproteomes in various genetic backgrounds revealed both documented and novel TORC1 effectors and allowed us to partition phosphorylation events between Tap42 and Sch9. Follow-up detailed characterization shows that Sch9 regulates RNA polymerases I and III, the latter via Maf1, in addition to translation initiation and the expression of ribosomal protein and ribosome biogenesis genes. This demonstrates that Sch9 is a master regulator of protein synthesis.
雷帕霉素靶蛋白复合体1（TORC1）是一种从酵母到人类都保守的重要多蛋白复合体。在有利的生长条件下，且在不存在大环内酯类雷帕霉素的情况下，TORC1具有活性，并几乎影响细胞生长的所有方面。尽管已经报道了酵母TORC1的两种直接效应器（Tap42，一种PP2A磷酸酶的调节剂；以及Sch9，一种AGC家族激酶），但将TORC1与其远端效应器偶联的信号通路尚未得到很好的理解。为了阐明这些通路，我们开发并采用了一种定量的、无标记质谱方法。对各种遗传背景下雷帕霉素敏感的磷酸化蛋白质组的分析揭示了已记录的和新的TORC1效应器，并使我们能够区分Tap42和Sch9之间的磷酸化事件。后续的详细表征表明，除了翻译起始以及核糖体蛋白和核糖体生物发生基因的表达外，Sch9还通过Maf1调节RNA聚合酶I和III。这表明Sch9是蛋白质合成的主要调节因子。
