Synapsin I senses membrane curvature by an amphipathic lipid packing sensor motif.

Institute of Chemistry and Biochemistry and Neurocure Cluster of Excellence, Freie Universität, 14195 Berlin, Germany.
Journal of Neuroscience (Impact Factor: 6.91). 12/2011; 31(49):18149-54. DOI: 10.1523/JNEUROSCI.4345-11.2011
Source: PubMed

ABSTRACT Sustained neurotransmitter release at synapses during high-frequency synaptic activity involves the mobilization of synaptic vesicles (SVs) from the tightly clustered reserve pool (RP). Synapsin I (Syn I), a brain-specific peripheral membrane protein that undergoes activity-dependent cycles of SV association and dissociation, is implicated in RP organization via its ability to cluster SVs. Although Syn I has affinity for phospholipids, the mechanism for the reversible association of synapsin with SV membranes remains enigmatic. Here, we show that rat Syn I is able to sense membrane curvature via an evolutionary conserved amphipathic lipid packing sensor motif (ALPS). Deletion or mutational inactivation of the ALPS impairs the ability of Syn I to associate with highly curved membranes and with SVs. Furthermore, a Syn I mutant lacking ALPS displays defects in its ability to undergo activity-induced cycles of dispersion and reclustering in neurons and fails to induce vesicle clustering in vitro. Our data suggest a crucial role for ALPS-mediated sensing of membrane curvature in regulating synapsin function.

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May 27, 2014