Rheb binds and regulates the mTOR kinase
Rheb binds and regulates the mTOR kinase
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DOI：
10.1016/j.cub.2005.02.053
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发表时间：
2005-04-26
期刊：
影响因子：
9.2
通讯作者：
Avruch, J
中科院分区：
文献类型：
--
作者：
Long, X;Lin, Y;Avruch, J
背景资料：雷帕霉素（TOR）的靶标与蛋白raptor和LST 8（TOR复合物1）复合，磷酸化p70 S6 K和4 E-BP 1以促进mRNA翻译。遗传学证据证实，体内TOR复合物活性需要小的GTdR heb，并且Rheb的过表达可以通过氨基酸提取来挽救体内TOR失活。的恶性硬化异源二聚体（TSC 1/TSC 2）的功能作为Rheb GT3激活剂和抑制TOR signaling in vivo.Results：在这里，我们表明，Rheb结合到TOR复合物特异性，独立于其能力，结合TSC 2，通过单独的相互作用与mTOR催化结构域和LST 8。Rheb在体内和体外与TOR复合物的结合不需要Rheb鸟苷酸充电，但受GTP调节并受开关1环中的某些突变（Ile 39 Lys）损害。核苷酸缺陷型Rheb突变体虽然能够在体内和体外结合mTOR，但在体内是抑制性的，并且在体内与核苷酸缺陷型Rheb缔合的mTOR多肽在体外缺乏激酶活性。相反地，与Rheb（GIn 64 Leu）结合的mTOR多肽（一种带近90%GTP电荷的突变体）表现出比与野生型Rheb结合的mTOR显著更高的蛋白激酶比活性。结论：TOR复合物1是Rheb-GTP的直接靶点，其结合能够激活TOR激酶。
Background: The target of rapamycin (TOR), in complex with the proteins raptor and LST8 (TOR complex 1), phosphorylates the p70S6K and 4E-BP1 to promote mRNA translation. Genetic evidence establishes that TOR complex activity in vivo requires the small GTPase Rheb, and overexpression of Rheb can rescue TOR from inactivation in vivo by amino-acid withdrawal. The Tuberous Sclerosis heterodimer (TSC1/TSC2) functions as a Rheb GTPase activator and inhibits TOR signaling in vivo.Results: Here, we show that Rheb binds to the TOR complex specifically, independently of its ability to bind TSC2, through separate interactions with the mTOR catalytic domain and with LST8. Rheb binding to the TOR complex in vivo and in vitro does not require Rheb guanyl nucleotide charging but is modulated by GTP and impaired by certain mutations (Ile39Lys) in the switch 1 loop. Nucleotide-deficient Rheb mutants, although capable of binding mTOR in vivo and in vitro, are inhibitory in vivo, and the mTOR polypeptides that associate with nucleotide-deficient Rheb in vivo lack kinase activity in vitro. Reciprocally, mTOR polypeptides bound to Rheb(GIn64Leu), a mutant that is nearly 90% GTP charged, exhibit substantially higher protein kinase specific activity than mTOR bound to wild-type Rheb. Conclusions: The TOR complex 1 is a direct target of Rheb-GTP, whose binding enables activation of the TOR kinase.