In situ structural analysis reveals membrane shape transitions during autophagosome formation.
In situ structural analysis reveals membrane shape transitions during autophagosome formation.
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原位结构分析揭示了自噬体形成过程中的膜形状转变。
DOI：
10.1073/pnas.2209823119
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发表时间：
2022-09-27
影响因子：
11.1
通讯作者：
中科院分区：
文献类型：
--
作者：
大自噬是（真核）细胞内稳态的基本降解过程，其中胞质物质被双膜自噬体吞噬以递送到裂解区室。在这项研究中，我们捕获酵母细胞内的自噬体生物合成的瞬态中间体在以前未达到的分辨率相关冷冻电子断层扫描（cryo-ET）。我们的自噬膜的定量分析揭示了意想不到的结构特征和形状的转变，从开放的吞噬细胞封闭的自噬体。我们进一步定义了自噬结构的亚细胞环境，揭示了与特定细胞器的极化接触位点。这些结果对自噬中的膜源和诱导吞噬体形状的力具有直接影响，从而突出了冷冻ET在生物物理学和细胞生物学结合处的潜力。自噬体是一种独特的细胞器，它以双膜囊泡的形式重新形成，吞噬胞质物质进行破坏。它们的生物发生涉及形态明显的中间体的膜转化，其超微结构知之甚少。在这里，我们结合联合收割机细胞生物学，相关的冷冻电子断层扫描（cryo-ET），和广泛的数据分析，揭示了一步一步的结构进展的自噬体生物合成直接在酵母细胞内的高分辨率。分析揭示了一个意想不到的薄的膜间距离，在吞噬细胞边缘扩张。基于几何特征的个体自噬结构到时间轴的映射揭示了生长中的吞噬细胞的膜形状和曲率的动态变化。此外，我们的断层图像显示了生长中的自噬体的细胞器相互作用组，突出了吞噬细胞和细胞器之间的接触部位的极性组织，如液泡和内质网（ER）。总的来说，这些发现对自噬过程中不同膜源的贡献以及在没有模板货物的情况下塑造和驱动吞噬细胞走向关闭的力量具有重要意义。
Macroautophagy is a degradation process fundamental for (eukaryotic) cellular homeostasis, in which cytosolic material is engulfed by a double-membrane autophagosome for delivery to a lytic compartment. In this study, we capture transient intermediates of autophagosome biogenesis within yeast cells at previously unattained resolution by correlative cryo-electron tomography (cryo-ET). Our quantitative analysis of autophagic membranes reveals unexpected structural features and shape transitions from open phagophores to closed autophagosomes. We further define the subcellular environment of autophagic structures, uncovering polarized contact sites with specific organelles. These results have direct implications for the membrane sources in autophagy and for the forces inducing phagophore shape, thus highlighting the potential of cryo-ET at the junction of biophysics and cell biology. Autophagosomes are unique organelles that form de novo as double-membrane vesicles engulfing cytosolic material for destruction. Their biogenesis involves membrane transformations of distinctly shaped intermediates whose ultrastructure is poorly understood. Here, we combine cell biology, correlative cryo-electron tomography (cryo-ET), and extensive data analysis to reveal the step-by-step structural progression of autophagosome biogenesis at high resolution directly within yeast cells. The analysis uncovers an unexpectedly thin intermembrane distance that is dilated at the phagophore rim. Mapping of individual autophagic structures onto a timeline based on geometric features reveals a dynamical change of membrane shape and curvature in growing phagophores. Moreover, our tomograms show the organelle interactome of growing autophagosomes, highlighting a polar organization of contact sites between the phagophore and organelles, such as the vacuole and the endoplasmic reticulum (ER). Collectively, these findings have important implications for the contribution of different membrane sources during autophagy and for the forces shaping and driving phagophores toward closure without a templating cargo.
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影响因子：
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作者：
Bertipaglia C;Schneider S;Jakobi AJ;Tarafder AK;Bykov YS;Picco A;Kukulski W;Kosinski J;Hagen WJ;Ravichandran AC;Wilmanns M;Kaksonen M;Briggs JA;Sachse C
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影响因子：
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Baba, M;Takeshige, K;Baba, N;Ohsumi, Y
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作者：
Hollenstein, David M.;Gomez-Sanchez, Rubeprimen;Kraft, Claudine
通讯作者：
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