Download MendeleyPhosphatidylinositol 4,5-Bisphosphate Clusters Act as Molecular Beacons for Vesicle Recruitment
Honigmann, A., Van Den Bogaart, G., Iraheta, E., Risselada, H.J., Milovanovic, D., Mueller, V., Muellar, S., Diederichsen, U., Fasshauer, D., Grubmuller, H., Hell, S.W., Eggeling, C., Kuhnel, K., Jahn, R.(2013) Nat Struct Mol Biol 20: 679
- PubMed: 23665582
- DOI: https://doi.org/10.1038/nsmb.2570
- Primary Citation of Related Structures:
2YOA - PubMed Abstract:
Synaptic-vesicle exocytosis is mediated by the vesicular Ca(2+) sensor synaptotagmin-1. Synaptotagmin-1 interacts with the SNARE protein syntaxin-1A and acidic phospholipids such as phosphatidylinositol 4,5-bisphosphate (PIP2). However, it is unclear how these interactions contribute to triggering membrane fusion. Using PC12 cells from Rattus norvegicus and artificial supported bilayers, we show that synaptotagmin-1 interacts with the polybasic linker region of syntaxin-1A independent of Ca(2+) through PIP2. This interaction allows both Ca(2+)-binding sites of synaptotagmin-1 to bind to phosphatidylserine in the vesicle membrane upon Ca(2+) triggering. We determined the crystal structure of the C2B domain of synaptotagmin-1 bound to phosphoserine, allowing development of a high-resolution model of synaptotagmin bridging two different membranes. Our results suggest that PIP2 clusters organized by syntaxin-1 act as molecular beacons for vesicle docking, with the subsequent Ca(2+) influx bringing the vesicle membrane close enough for membrane fusion.
Organizational Affiliation:
Department of Nanobiophotonics, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany.
