The structure of the COPI coat determined within the cell
- European Molecular Biology Laboratory, Germany
- Max Planck Institute of Biochemistry, Germany
Abstract
COPI-coated vesicles mediate trafficking within the Golgi apparatus and from the Golgi to the endoplasmic reticulum. The structures of membrane protein coats, including COPI, have been extensively studied with in vitro reconstitution systems using purified components. In a previous paper (Dodonova et al., 2017), we determined a complete structural model of the in vitro reconstituted COPI coat. Here, we applied cryo-focused ion beam milling, cryo-electron tomography and subtomogram averaging to determine the native structure of the COPI coat within vitrified Chlamydomonas reinhardtii cells. The native algal structure resembles the in vitro mammalian structure, but additionally reveals cargo bound beneath β'-COP. We find that all coat components disassemble simultaneously and relatively rapidly after budding. Structural analysis in situ, maintaining Golgi topology, shows that vesicles change their size, membrane thickness, and cargo content as they progress from cis to trans, but the structure of the coat machinery remains constant.
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Article and author information
Author details
Svetlana O Dodonova
Funding
Deutsche Forschungsgemeinschaft (SFB1129 (Z2))
- John AG Briggs
Deutsche Forschungsgemeinschaft (SFB-1035/Project A01)
- Wolfgang Baumeister
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2017, Bykov et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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The structure of the COPI coat determined within the cell
eLife 6:e32493.
https://doi.org/10.7554/eLife.32493
Further reading
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- Structural Biology and Molecular Biophysics
- Cell Biology
Advances in imaging techniques have shed new light on the structure of vesicles formed by COPI protein complexes.
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- Structural Biology and Molecular Biophysics
Previously, we reported that α-synuclein (α-syn) clusters synaptic vesicles (SV) Diao et al., 2013, and neutral phospholipid lysophosphatidylcholine (LPC) can mediate this clustering Lai et al., 2023. Meanwhile, post-translational modifications (PTMs) of α-syn such as acetylation and phosphorylation play important yet distinct roles in regulating α-syn conformation, membrane binding, and amyloid aggregation. However, how PTMs regulate α-syn function in presynaptic terminals remains unclear. Here, based on our previous findings, we further demonstrate that N-terminal acetylation, which occurs under physiological conditions and is irreversible in mammalian cells, significantly enhances the functional activity of α-syn in clustering SVs. Mechanistic studies reveal that this enhancement is caused by the N-acetylation-promoted insertion of α-syn’s N-terminus and increased intermolecular interactions on the LPC-containing membrane. N-acetylation in our work is shown to fine-tune the interaction between α-syn and LPC, mediating α-syn’s role in synaptic vesicle clustering.
