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PMID: 20512644 Published · ppublish English Journal Article Research Support, N.I.H., Extramural

SNARE complex zipping as a driving force in the dilation of proteinaceous fusion pores.

The Journal of membrane biology ·Vol. 235 ·No. 2 ·2010-06-00 ·Pages 89-100

Jackson MB

Abstract

The assembly of SNARE proteins into a tight complex has been hypothesized to drive membrane fusion. A model of the initial fusion pore as a proteinaceous channel formed by SNARE proteins places their membrane anchors in separate membranes. This leaves the possibility of a final assembly step that brings the membrane anchors together and drives fusion pore expansion. The present study develops a model for expansion in which the final SNARE complex zipping step drives a transition from a proteinaceous fusion pore to a lipidic fusion pore. An estimate of the energy released upon merger of the helical segments of the SNARE motifs with the helical segments of the membrane anchors indicates that completing the assembly of a few SNARE complexes can overcome the elastic energy that opposes lipid bilayer deformation into a narrow fusion pore. The angle between the helical axes of the membrane anchor and SNARE motif serves as a useful reaction coordinate for this transition. Energy was calculated as a function of this angle, incorporating contributions from membrane bending, SNARE complex assembly, membrane anchor flexing and hydrophobic interactions. The rate of this transition was evaluated as a process of diffusion over the barrier imposed by these combined energies, and the rates estimated were consistent with experimental measurements.

MeSH Terms
Animals Exocytosis/physiology Humans Lipid Bilayers/chemistry,metabolism Membrane Fusion/physiology Membrane Proteins/chemistry,metabolism Models, Biological Models, Theoretical SNARE Proteins/chemistry,metabolism
Chemicals
Lipid Bilayers Membrane Proteins SNARE Proteins
Authors & Affiliations
1 authors, click to expand affiliations / ORCID
Jackson Meyer B
Department of Physiology, University of Wisconsin, Madison, USA. mjackson@physiology.wisc.edu
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Article Info
Journal
The Journal of membrane biology
Abbr.
J Membr Biol
ISSN
1432-1424
DOI
10.1007/s00232-010-9258-1
Email
mjackson@physiology.wisc.edu
Published
2010-06-00
Epub
2010-00-30
Pages
89-100
Language
English
Region
United States
NLM ID
0211301
PMCID
PMC2944410
Subset
IM
Grants
NINDS NIH HHS · NS44057 · United States
NINDS NIH HHS · R01 NS044057-08 · United States
NINDS NIH HHS · R01 NS044057-09 · United States
NINDS NIH HHS · R01 NS044057 · United States
NINDS NIH HHS · R01 NS044057-07 · United States
External Links
PubMed source DOI: 10.1007/s00232-010-9258-1 PMC Full Text View journal details
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