一个Rag GTPase激活检查点的结构机制
Rosalie E Lawrence1,2, Simon A Fromm1, Yangxue Fu1
1Department of Molecular and Cell Biology, University of California at Berkeley, Berkeley, CA 94720, USA.
概括
瘤抑制素 (FLCN) 调节mTORC1的信号传递. 它的溶解体功能通过冷EM被发现,作为控制溶解体生物发生的检查点.
科学领域:
- 细胞生物学
- 分子生物学
- 生物化学
背景情况:
- 瘤抑制素 (FLCN) 对于mTORC1信号的营养依赖激活至关重要.
- 对于mTORC1的一个关键调节剂RagC,FLCN表现出关三酸酶 (GTPase) 激活蛋白 (GAP) 的活性.
- 在饥饿过程中,FLCN从细胞质转移到 lysosomes,这表明它在 lysosomal 功能中的作用.
研究的目的:
- 通过确定人类溶酶体FLCN复合体 (LFC) 的结构来阐明FLCN的溶酶体功能.
- 了解FLCN的GAP活动是如何在 lysosomal环境中调节的.
- 研究LFC在控制mTORC1信号和溶酶体生物发生中的作用.
主要方法:
- 包括FLCN,FNIP2,RagAGDP:RagCGTP和Ragulator复合体在内的人类溶解体FLCN复合体 (LFC) 的复合.
- 在3.6安格斯特罗姆分辨率下确定LFC的冷电子显微镜 (cryo-EM) 结构.
- 在复制的LFC中分析FLCN的RagC-GAP活性.
主要成果:
- 冷-EM结构显示,由于催化性氨酸残留物的固体阻碍,FLCN的RagC-GAP活性在LFC中受到抑制.
- 拆解LFC可以释放FLCN的GAP活动.
- 这种调节的GAP活性会影响转录因子E3的mTORC1依赖调节,这是溶酶体生物发生的主调节者.
结论:
- 溶酶体FLCN复合体 (LFC) 作为mTORC1信号传递中的关键检查点.
- 在LFC中的FLCN抑制状态防止营养缺乏期间的mTORC1过早激活.
- 通过LFC的调节分解,可以对细胞信号进行适当的 lysosomal biogenesis控制.
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