通过RHEB激活mTORC1和通过PRAS40抑制的机制
Haijuan Yang1, Xiaolu Jiang1,2, Buren Li1
1Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, New York 10065, USA.
Nature
|December 14, 2017
概括
拉巴胺素复合物1 (mTORC1) 结构的机理性标揭示了RHEB结合如何激活激酶以及癌症突变如何模仿这种激活. 这些见解解释了mTORC1基质的选择和调节.
科学领域:
- 生物化学
- 结构生物学
- 细胞生物学
背景情况:
- 拉巴胺复合体1 (mTORC1) 的机械标是细胞生长和新陈代谢的关键调节剂.
- mTORC1的活动由营养素,能量状态和生长因子调节.
- 主要成分包括mTOR激酶,RAPTOR,RHEB (激活剂) 和PRAS40 (抑制剂).
研究的目的:
- 阐明 mTORC1 激活和调节的结构机制.
- 调查RHEB在异质激活mTORC1激酶活性中的作用.
- 通过PRAS40定义基质识别和抑制的结构基础.
主要方法:
- 用冷电子显微镜 (cryo-EM) 确定mTORC1和激活的RHEB-mTORC1的结构.
- 进行X射线晶体学以解析RAPTOR-TOS动机复合体,mTOR FRB基质复合体和mTOR-PRAS40复合体的结构.
- 生物化学测试以评估激酶活性和突变的影响.
主要成果:
- RHEB-mTORC1的冷-EM结构显示,RHEB结合会诱导全局形状变化,从而以异构方式激活mTOR激酶活性部位.
- 与癌症相关的突变被映射到保持不活跃状态的区域,表明它们模仿RHEB介导的激活.
- 晶体结构定义了RAPTOR的TOS模式识别,并通过mTORFRB域确定了第二个基质招募机制.
- 据证实,PRAS40可以抑制两种基质招募部位.
结论:
- 结构和生化数据解释了mTORC1如何选择基质以及如何调节其激酶活性.
- 这些发现提供了对mTORC1激活和癌症相关突变的机制见解.
- 这些发现为了解癌症等疾病中的mTORC1失调提供了基础.
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