Department of Molecular Biology and Institute of Genetics and Genomics of Geneva (iGE3), University of Geneva, 30 Quai Ernest Ansermet, CH1211 Geneva, Switzerland.
European Molecular Biology Laboratory, Grenoble Outstation, 71 Avenue des Martyrs, 38042 Grenoble, France; Fondation ARC, 9 rue Guy Môquet, BP 90003, 04803 Villejuif Cedex, France.
Mol Cell. 2015 Jun 18;58(6):977-88. doi: 10.1016/j.molcel.2015.04.031. Epub 2015 May 28.
Target of Rapamycin (TOR) plays central roles in the regulation of eukaryote growth as the hub of two essential multiprotein complexes: TORC1, which is rapamycin-sensitive, and the lesser characterized TORC2, which is not. TORC2 is a key regulator of lipid biosynthesis and Akt-mediated survival signaling. In spite of its importance, its structure and the molecular basis of its rapamycin insensitivity are unknown. Using crosslinking-mass spectrometry and electron microscopy, we determined the architecture of TORC2. TORC2 displays a rhomboid shape with pseudo-2-fold symmetry and a prominent central cavity. Our data indicate that the C-terminal part of Avo3, a subunit unique to TORC2, is close to the FKBP12-rapamycin-binding domain of Tor2. Removal of this sequence generated a FKBP12-rapamycin-sensitive TORC2 variant, which provides a powerful tool for deciphering TORC2 function in vivo. Using this variant, we demonstrate a role for TORC2 in G2/M cell-cycle progression.
雷帕霉素靶蛋白（TOR）作为两个必需的多蛋白复合物的中心，在真核生物生长的调节中起着核心作用：雷帕霉素敏感的 TORC1 和特征不那么明显的 TORC2。TORC2 是脂质生物合成和 Akt 介导的存活信号的关键调节剂。尽管它很重要，但它的结构及其对雷帕霉素不敏感的分子基础尚不清楚。我们使用交联质谱和电子显微镜来确定 TORC2 的结构。TORC2 呈菱形，具有拟 2 重对称和突出的中央腔。我们的数据表明，Avo3 的 C 端部分，TORC2 特有的亚基，靠近 Tor2 的 FKBP12-雷帕霉素结合域。去除这个序列产生了一个 FKBP12-雷帕霉素敏感的 TORC2 变体，这为在体内破译 TORC2 功能提供了一个强大的工具。使用这个变体，我们证明了 TORC2 在 G2/M 细胞周期进程中的作用。
