Exocyst dynamics during vesicle tethering and fusion
Syed Mukhtar Ahmed1, Hisayo Nishida-Fukuda2,3,4,5, Yuchong Li6,7
1Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN, 37240, USA. syed.m.ahmed@vanderbilt.edu.
Nature Communications
|December 5, 2018
Summary
The exocyst complex, crucial for vesicle transport, is dynamic in mammalian cells. It functions as two independent subcomplexes that assemble and disassemble during exocytosis.
Area of Science:
- Cell biology
- Molecular biology
- Biochemistry
Background:
- The exocyst complex is essential for tethering vesicles to the plasma membrane during exocytosis.
- Mechanisms of exocyst assembly and delivery in mammalian cells are not well understood.
Purpose of the Study:
- To investigate the dynamic assembly and disassembly mechanisms of the exocyst complex in mammalian cells.
- To characterize the behavior of exocyst subunits during vesicle tethering and fusion.
Main Methods:
- Utilized Cas9 gene-editing to create sfGFP or Halo-tagged endogenous exocyst subunit knock-in cell lines.
- Employed high-speed imaging and correlation spectroscopy to analyze exocyst dynamics in mammary epithelial cells.
Main Results:
- Mammalian exocyst exists as dynamic tetrameric subcomplexes that associate independently with vesicles and the plasma membrane.
- Subcomplexes are in equilibrium with octameric and monomeric forms, with distinct subunit departure times around fusion.
- Approximately 9 exocyst complexes associate per vesicle.
Conclusions:
- The mammalian exocyst functions as a dynamic, two-part complex with independent subcomplexes.
- Provides novel insights into the assembly and disassembly processes governing exocytosis in mammalian systems.
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