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Solution structure of the ESCRT-I and -II supercomplex: implications for membrane budding and scission
Evzen Boura1, Bartosz Różycki, Hoi Sung Chung
1Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
Structure (London, England : 1993)
|May 15, 2012
Summary
The ESCRT-I-II supercomplex stabilizes endosomal membrane buds for protein degradation. Its dynamic structures coordinate cargo sorting, offering a general model for multiprotein assemblies.
Area of Science:
- Cell Biology
- Structural Biology
- Biochemistry
Background:
- The ESCRT-I and ESCRT-II supercomplex drives membrane budding into endosomes.
- This process is crucial for the lysosomal degradation of ubiquitinated membrane proteins.
Purpose of the Study:
- To determine the solution conformation of the yeast ESCRT-I-II supercomplex.
- To elucidate the mechanism of membrane budding and cargo sorting.
Main Methods:
- Small-angle X-ray scattering (SAXS)
- Single-molecule Förster resonance energy transfer (smFRET)
- Double electron-electron resonance (DEER) spectroscopy
- Hybrid refinement of structural ensembles
Main Results:
- An ensemble of 18 ESCRT-I-II supercomplex structures was generated, showing conformational flexibility from compact to extended states.
- The supercomplex adopts crescent shapes, providing a structural basis for its function.
- The structures reveal how ESCRT-I-II stabilizes membrane buds and sorts cargo within nascent bud necks.
Conclusions:
- The ESCRT-I-II supercomplex plays a key role in endosomal sorting and protein degradation.
- The determined structures offer a detailed mechanistic model for membrane budding.
- The hybrid refinement approach is broadly applicable to studying dynamic multiprotein assemblies.
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