线粒体TIM23复合体的光映射揭示了一个面向水的,基质相互作用的螺旋表面
Nathan N Alder1, Robert E Jensen, Arthur E Johnson
1Department of Molecular and Cellular Medicine, Texas A&M Health Science Center, College Station, TX 77843-1114, USA.
Cell
|August 12, 2008
概括
研究人员使用光探针绘制了线粒体中TIM23复杂通道的结构. 这揭示了蛋白质在进口过程中如何穿越内线粒体膜.
科学领域:
- 线粒体生物学 线粒体生物学
- 蛋白质的运输蛋白质的运输
- 膜生物物理学 膜生物物理学
背景情况:
- 蛋白质穿过线粒体内膜的转移对于细胞功能至关重要,由TIM23复合体介导.
- Tim23子单元的精确结构,特别是形成蛋白质导电通道的区域,仍然在很大程度上是未知的.
研究的目的:
- 在完整的线粒体中研究功能性TIM23复合体内的Tim23子单元的高分辨率结构和环境.
- 为了确定与进口蛋白相互作用的Tim23的区域,并了解通道关门机制.
主要方法:
- 使用了对环境敏感的光探头,每个都在Tim23衍生品的特定位置,集成到功能性TIM23复合体中.
- 采用多种光谱技术来分析活跃线粒体内的探针环境.
- 将光数据与交叉连接研究结合起来,以绘制蛋白质导通通道内的探头位置.
主要成果:
- 在Tim23的跨膜区域内确定了一个alpha-helical结构,位于两环境中.
- 在蛋白质进口过程中观察到水面螺旋表面的探头的特定光谱变化,表明了动态结构变化.
- 评估探头对火剂的可访问性,为通道封闭过程提供了洞察力.
结论:
- 提供了一个前所未有的,高分辨率的视图,在一个完全可操作的,膜嵌入式复合体内,一个跨位置通道结构.
- 阐明了通过TIM23通道进行蛋白质转移的结构基础,并提供了对其动态调节的见解.
- 证明了特定地点的光探针在现场研究膜蛋白质复合物的实用性.
相关概念视频
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01:39Mitochondrial Protein Sorting
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Most of these mitochondrial proteins are encoded by the nucleus and imported to the mitochondria as unfolded or loosely folded precursors. Mitochondrial precursors...
Most of these mitochondrial proteins are encoded by the nucleus and imported to the mitochondria as unfolded or loosely folded precursors. Mitochondrial precursors...
01:19Translocation of Proteins into the Mitochondria
Mitochondrial precursors are translocated to the internal subcompartments via independent mechanisms involving distinct protein machineries called translocases.
Sorting of outer membrane proteins:
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Sorting of outer membrane proteins:
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01:37Energy to Drive Translocation
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Generally, polypeptides are unfolded by two distinct...
Generally, polypeptides are unfolded by two distinct...
01:12Porin Insertion in the Outer Mitochondrial Membrane
Porins are beta-barrel proteins translocated to the mitochondrial outer membrane through the TOM complex into the intermembrane space. Porin precursors bind TIM chaperones within the intermembrane space and are guided to the Sorting and Assembly Machinery complex or SAM complex on the outer mitochondrial membrane.
Three models describe the assembly of porins by the SAM complex and their insertion into the outer membrane. Model 1 suggests that porins are assembled outside the SAM channel as the...
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01:34Protein Transport into the Inner Mitochondrial Membrane
Nuclear encoded mitochondrial precursors are imported to the inner membrane in a multistep process involving two separate translocons, TIM22 and TIM23. TIM23 is a cation-selective pore that remains closed by the N terminal segment of the protein. Negative charges on the TIM23 act as a receptor for the incoming precursor, pulling the positively charged matrix-targeting sequence for peptide insertion and translocation.
Transport of mitochondrial precursors across the TIM23 channel is driven by...
Transport of mitochondrial precursors across the TIM23 channel is driven by...