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Two distinct effects on neurotransmission in a temperature‐sensitive SNAP‐25 mutant
Author(s) -
Rao Sujata S.,
Stewart Bryan A.,
Rivlin Patricia K.,
Vilinsky Ilya,
Watson Brendon O.,
Lang Cynthia,
Boulianne Gabrielle,
Salpeter Miriam M.,
Deitcher David L.
Publication year - 2001
Publication title -
the embo journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 7.484
H-Index - 392
eISSN - 1460-2075
pISSN - 0261-4189
DOI - 10.1093/emboj/20.23.6761
Subject(s) - biology , mutant , snare complex , neurotransmitter , snap , microbiology and biotechnology , neurotransmission , synaptic vesicle , lipid bilayer fusion , mutation , vesicle , biophysics , receptor , biochemistry , membrane , gene , computer graphics (images) , computer science
Vesicle fusion in eukaryotic cells is mediated by SNAREs (soluble N ‐ethylmaleimide‐sensitive factor attachment protein receptors). In neurons, the t‐SNARE SNAP‐25 is essential for synaptic vesicle fusion but its exact role in this process is unknown. We have isolated a SNAP‐25 temperature‐sensitive paralytic mutant in Drosophila , SNAP‐25 ts . The mutation causes a Gly50 to Glu change in SNAP‐25's first amphipathic helix. A similar mutation in the yeast homologue SEC9 also results in temperature sensitivity, implying a conserved role for this domain in secretion. In vitro ‐generated 70 kDa SNARE complexes containing SNAP‐25 ts are thermally stable but the mutant SNARE multimers (of ∼120 kDa) rapidly dissociate at 37°C. The SNAP‐25 ts mutant has two effects on neurotransmitter release depending upon temperature. At 22°C, evoked release of neurotransmitter in SNAP‐25 ts larvae is greatly increased, and at 37°C, the release of neurotransmitter is reduced as compared with controls. Our data suggest that at 22°C the mutation causes the SNARE complex to be more fusion competent but, at 37°C the same mutation leads to SNARE multimer instability and fusion incompetence.