线粒体氨酸的基于寡合体的功能
Hironori Takeda1,2, Saori Shinoda1,3, Chiho Goto1
1Faculty of Life Sciences, Kyoto Sangyo University, Kyoto, Japan.
Nature communications
|July 27, 2025
概括
酵母蛋白 (Por1) 组合,除了其运输作用外,还促进了线粒体蛋白质的进口,维持了外膜脂质组成,并调节了线粒体DNA. 这项研究揭示了这个关键线粒体通道的新功能.
科学领域:
- 线粒体生物学 线粒体生物学
- 结构生物学是结构生物学.
- 分子和细胞生物学分子和细胞生物学.
背景情况:
- 氨酸,也称为电压依赖性离子通道 (VDAC),是线粒体外膜中的关键β-桶通道.
- 它对于运输小分子和离子至关重要,并在亡和炎症反应中发挥重要作用.
研究的目的:
- 为了确定酵母素 (Por1) 在六合体形式的高分辨率冷电子显微镜结构.
- 通过在原质体接口引入突变来研究Por1组件的功能,超越其正规的运输作用.
主要方法:
- 电子显微镜 (cryo-EM) 用于确定六米酵母素 (Por1) 的3.2 Å分辨率结构.
- 在原质体接口的位点定向突变发生,以探测Por1组装功能.
- 使用Por1突变体对相互作用蛋白质 (包括核酶) 的查.
主要成果:
- 这项研究揭示了酵母葡萄素 (Por1) 的六米结构,分辨率为3.2 Å.
- 突变性确定了Por1组装的三个关键功能:结合未组装的Tom22以帮助线粒体蛋白质的进口,作为外膜脂质平衡的脂质杂化酶,并调节线粒体DNA的保留和损失.
- 在线粒体DNA管理中与Por1合作的核酶的识别.
结论:
- 酵母葡萄素 (Por1) 组合具有多方面的作用,不仅仅是离子和代谢物运输.
- Por1是线粒体蛋白质进口,膜脂质调节和线粒体DNA稳定性的组成部分.
- Por1突变的结构洞察力和功能表征为进一步研究线粒体动力学和功能障碍提供了基础.
相关概念视频
01:21Structure of Porins
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Mitochondria, chloroplasts, and gram-negative bacteria have transmembrane, beta-barrel proteins called porins to mediate the free diffusion of ions and metabolites across the membrane. Mitochondrial porin precursors contain conserved amino acid sequences called beta signals at their C-terminal. Beta signals have a motif of PoXGXXHyXHy (Po-Polar, X-Any amino acid, G-Glycine, Hy-LargeHydrophobic), which are crucial for precursor recognition to initiate precursor assembly. Beta-barrel...
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01:12Porin Insertion in the Outer Mitochondrial Membrane
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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...
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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01:39Mitochondrial Protein Sorting
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Mitochondria are double-membrane organelles of the eukaryotes involved in cellular metabolism, signaling, ATP synthesis, and programmed cell death. Each of these processes requires specific proteins and enzymes that must be correctly sorted to the right mitochondrial subcompartment for the proper functioning of the organelle.
Most of these mitochondrial proteins are encoded by the nucleus and imported to the mitochondria as unfolded or loosely folded precursors. Mitochondrial precursors...
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01:45Mitochondrial Membranes
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A single mitochondrion is a bean-shaped organelle enclosed by a double-membrane system. The outer membrane of mitochondria is smooth and contains many porins - the integral membrane transporters. Porins enable free diffusion of ions and small uncharged molecules through the outer mitochondrial membrane but limit the transport of molecules larger than 5000 Daltons. Further, the outer mitochondrial membrane forms a unique structure called membrane contact sites with other subcellular organelles,...
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01:34Protein Transport into the Inner Mitochondrial Membrane
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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.
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01:39Mitochondrial Precursor Proteins
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Mitochondrial precursors are partially unfolded or loosely folded polypeptide chains. Newly synthesized precursors are inhibited from spontaneously folding into their native conformation by the cytosolic chaperones, heat shock proteins 70 (Hsp70), and mitochondrial import stimulation factors (MSFs). Precursors bound to MSFs are guided to the TOM70-TOM37 receptors, while precursors bound to Hsp70 chaperones are targetted to TOM20-TOM22 receptor complexes.
Most of the mitochondrial...
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