Subtomogram averaging of COPII assemblies reveals how coat organization dictates membrane shape.
Subtomogram averaging of COPII assemblies reveals how coat organization dictates membrane shape.
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DOI：
10.1038/s41467-018-06577-4
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发表时间：
2018-10-08
影响因子：
16.6
通讯作者：
Zanetti G
中科院分区：
文献类型：
--
作者：
Hutchings J;Stancheva V;Miller EA;Zanetti G
真核细胞利用膜结合载体在区室之间运输货物，这一过程对细胞功能至关重要。载体是由将货物捕获与膜变形耦合的涂层复合物产生的。 COPII 涂层通过在内层和外层组装来介导内质网的输出，产生不同形状和大小的载体，从而允许分泌数千种不同的货物。尽管对 COPII 亚基有了详细的了解，但涂层组装和膜变形的分子机制尚不清楚。在这里，我们展示了体外重建的膜结合内层的 4.9 Å 冷冻断层扫描亚断层图平均结构。我们发现外层 (Sec13–Sec31) 桥接内层亚基 (Sar1–Sec23–Sec24)，促进它们组装成紧密的晶格。我们直接观察膜嵌入的 Sar1 两亲性螺旋，揭示晶格形成诱导平行螺旋插入，产生管状曲率。我们建议像前胶原受体 TANGO1 这样的调节因子可以调节这种机制来确定囊泡的形状和大小。 COPII 外壳组装成两个同心层并介导内质网的蛋白质输出。在这里，作者展示了通过体外重建获得的膜结合 COPII 内层的 4.9 Å 分辨率冷冻断层扫描和亚断层图平均结构，并讨论了其机制含义。
Eukaryotic cells employ membrane-bound carriers to transport cargo between compartments in a process essential to cell functionality. Carriers are generated by coat complexes that couple cargo capture to membrane deformation. The COPII coat mediates export from the endoplasmic reticulum by assembling in inner and outer layers, yielding carriers of variable shape and size that allow secretion of thousands of diverse cargo. Despite detailed understanding of COPII subunits, the molecular mechanisms of coat assembly and membrane deformation are unclear. Here we present a 4.9 Å cryo-tomography subtomogram averaging structure of in vitro-reconstituted membrane-bound inner coat. We show that the outer coat (Sec13–Sec31) bridges inner coat subunits (Sar1–Sec23–Sec24), promoting their assembly into a tight lattice. We directly visualize the membrane-embedded Sar1 amphipathic helix, revealing that lattice formation induces parallel helix insertions, yielding tubular curvature. We propose that regulators like the procollagen receptor TANGO1 modulate this mechanism to determine vesicle shape and size. The COPII coat assembles in two concentric layers and mediates protein export from the endoplasmic reticulum. Here the authors present the 4.9 Å resolution cryo-tomography and subtomogram averaging structure of the membrane bound COPII inner coat that was obtained by in vitro reconstitution and discuss mechanistic implications.
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SAR1 GTPase周期的调节对于内质网的大型货物分泌是必要的。
影响因子：
5.5
作者：
Saito K;Maeda M;Katada T
通讯作者：
Katada T
DOI：
10.1083/jcb.201312062
发表时间：
2014-09-15
期刊：
The Journal of cell biology
影响因子：
--
作者：
Saito K;Yamashiro K;Shimazu N;Tanabe T;Kontani K;Katada T
通讯作者：
Katada T
影响因子：
3
作者：
Kremer, JR;Mastronarde, DN;McIntosh, JR
通讯作者：
McIntosh, JR
影响因子：
64.5
作者：
Lee, MCS;Orci, L;Schekman, R
通讯作者：
Schekman, R
影响因子：
4.6
作者：
Bacia, Kirsten;Futai, Eugene;Prinz, Simone;Meister, Annette;Daum, Sebastian;Glatte, Daniela;Briggs, John A. G.;Schekman, Randy
通讯作者：
Schekman, Randy