ジャーナル: Nature / 年: 2017 タイトル: Mechanisms of mTORC1 activation by RHEB and inhibition by PRAS40. 著者: Haijuan Yang / Xiaolu Jiang / Buren Li / Hyo J Yang / Meredith Miller / Angela Yang / Ankita Dhar / Nikola P Pavletich / 要旨: The mechanistic target of rapamycin complex 1 (mTORC1) controls cell growth and metabolism in response to nutrients, energy levels, and growth factors. It contains the atypical kinase mTOR and the ...The mechanistic target of rapamycin complex 1 (mTORC1) controls cell growth and metabolism in response to nutrients, energy levels, and growth factors. It contains the atypical kinase mTOR and the RAPTOR subunit that binds to the Tor signalling sequence (TOS) motif of substrates and regulators. mTORC1 is activated by the small GTPase RHEB (Ras homologue enriched in brain) and inhibited by PRAS40. Here we present the 3.0 ångström cryo-electron microscopy structure of mTORC1 and the 3.4 ångström structure of activated RHEB-mTORC1. RHEB binds to mTOR distally from the kinase active site, yet causes a global conformational change that allosterically realigns active-site residues, accelerating catalysis. Cancer-associated hyperactivating mutations map to structural elements that maintain the inactive state, and we provide biochemical evidence that they mimic RHEB relieving auto-inhibition. We also present crystal structures of RAPTOR-TOS motif complexes that define the determinants of TOS recognition, of an mTOR FKBP12-rapamycin-binding (FRB) domain-substrate complex that establishes a second substrate-recruitment mechanism, and of a truncated mTOR-PRAS40 complex that reveals PRAS40 inhibits both substrate-recruitment sites. These findings help explain how mTORC1 selects its substrates, how its kinase activity is controlled, and how it is activated by cancer-associated mutations.
構造決定の手法: 単一同系置換・異常分散 / 解像度: 3→20 Å / Cor.coef. Fo:Fc: 0.911 / Cor.coef. Fo:Fc free: 0.885 / SU B: 48.25 / SU ML: 0.379 / 交差検証法: THROUGHOUT / ESU R Free: 0.491 / 立体化学のターゲット値: MAXIMUM LIKELIHOOD / 詳細: HYDROGENS HAVE BEEN ADDED IN THE RIDING POSITIONS
Rfactor
反射数
%反射
Selection details
Rfree
0.26771
1007
4 %
RANDOM
Rwork
0.22735
-
-
-
obs
0.229
24264
91.17 %
-
溶媒の処理
イオンプローブ半径: 0.8 Å / 減衰半径: 0.8 Å / VDWプローブ半径: 1 Å / 溶媒モデル: MASK