Article: article d'un périodique ou d'un magazine.
Is assembly of the SNARE complex enough to fuel membrane fusion?
Journal of Biological Chemistry
Date de publication
The three key players in the exocytotic release of neurotransmitters from synaptic vesicles are the SNARE (soluble N-ethylmaleimide-sensitive factor attachment protein receptor) proteins synaptobrevin 2, syntaxin 1a, and SNAP-25. Their assembly into a tight four-helix bundle complex is thought to pull the two membranes into close proximity. It is debated, however, whether the energy generated suffices for membrane fusion. Here, we have determined the thermodynamic properties of the individual SNARE assembly steps by isothermal titration calorimetry. We found extremely large favorable enthalpy changes counterbalanced by positive entropy changes, reflecting the major conformational changes upon assembly. To circumvent the fact that ternary complex formation is essentially irreversible, we used a stabilized syntaxin-SNAP-25 heterodimer to study synaptobrevin binding. This strategy revealed that the N-terminal synaptobrevin coil binds reversibly with nanomolar affinity. This suggests that individual, membrane-bridging SNARE complexes can provide much less pulling force than previously claimed.
Calorimetry, Circular Dichroism, Dimerization, Humans, Liposomes, Membrane Fusion/physiology, Protein Conformation, Qa-SNARE Proteins/metabolism, R-SNARE Proteins/metabolism, SNARE Proteins/metabolism, Synaptic Vesicles/metabolism, Synaptosomal-Associated Protein 25/metabolism
Web of science
Création de la notice
Dernière modification de la notice