Data for: Screening of stapled peptides for inhibition of calcium-triggered exocytosis

The so-called primary interface between the SNARE complex and
synaptotagmin-1 (Syt1) is essential for Ca2+-triggered neurotransmitter
release in neuronal synapses. The interacting residues of the primary
interface are conserved across different species for synaptotagmins (Syt1,
Syt2, Syt9), SNAP-25, and syntaxin-1A homologs involved in fast
synchronous release. This Ca2+-independent interface forms prior to
Ca2+-triggering and plays a role in synaptic vesicle priming. This primary
interface is also conserved in the fusion machinery, that is, responsible
for mucin granule membrane fusion. Ca2+ stimulated mucin secretion is
mediated by the SNAREs syntaxin-3, SNAP-23, VAMP8, synaptotagmin-2, and
other proteins. Here, we designed and screened a series of
hydrocarbon-stapled peptides consisting of SNAP-25 fragments that included
some of the key residues involved in the primary interface as observed in
high-resolution crystal structures. We selected a subset of four stapled
peptides that were highly α-helical as assessed by circular dichroism and
that inhibited both Ca2+-independent and Ca2+-triggered ensemble
lipid-mixing with neuronal SNAREs and Syt1. In a single-vesicle
content-mixing assay with reconstituted neuronal SNAREs and
synaptotagmin-1 or with reconstituted airway SNAREs and synaptotagmin-2,
the selected peptides also suppressed Ca2+-triggered fusion. Taken
together, hydrocarbon-stapled peptides that interfere with the primary
interface consequently inhibit Ca2+-triggered exocytosis. Our inhibitor
screen suggests that these compounds may be useful to combat mucus
hypersecretion, that is, a major cause of airway obstruction in the
pathophysiology of asthma and cystic fibrosis.