Dilation of fusion pores by crowding of SNARE proteins
- School of Medicine, Yale University, United States
- Yale University, United States
- Columbia University, United States
Abstract
Hormones and neurotransmitters are released through fluctuating exocytotic fusion pores that can flicker open and shut multiple times. Cargo release and vesicle recycling depend on the fate of the pore, which may reseal or dilate irreversibly. Pore nucleation requires zippering between vesicle-associated v- and target membrane t-SNAREs, but the mechanisms governing the subsequent pore dilation are not understood. Here, we probed dilation of single fusion pores using v-SNARE-reconstituted ~23 nm diameter discoidal nanolipoprotein particles (vNLPs) as fusion partners with cells ectopically expressing cognate, 'flipped' t-SNAREs. Pore nucleation required a minimum of 2, and reached a maximum above ~4 copies per face, but the probability of pore dilation was far from saturating at 15 copies, the NLP capacity. Our experimental and computational results suggest SNARE availability may be pivotal in determining whether neurotransmitters or hormones are released through a transient (kiss & run) or an irreversibly dilating pore (full fusion).
Article and author information
Author details
Shyam S Krishnakumar
Funding
National Institute of General Medical Sciences (R01GM108954)
- Erdem Karatekin
Kavli Foundation (Neuroscience Scholar Award)
- Erdem Karatekin
Deutsche Forschungsgemeinschaft (VE760/1-1)
- Wensi Vennekate
National Institute of Diabetes and Digestive and Kidney Diseases (R01DK027044)
- Shyam S Krishnakumar
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2017, Wu 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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Dilation of fusion pores by crowding of SNARE proteins
eLife 6:e22964.
https://doi.org/10.7554/eLife.22964
