The Liprin homology domain is essential for the homomeric interaction of SYD-2/Liprin-α protein in presynaptic assembly.
Synapses are asymmetric structures that are specialized for neuronal signal transduction. A unique set of proteins is present at the presynaptic active zone, which is a core structure essential for neurotransmitter release. In Caenorhabditis elegans HSN neurons, SYD-2, a Liprin-α family protein, acts together with a GAP protein SYD-1 to ... promote presynaptic assembly. Previous studies have shown that elevating the activity of syd-2 can bypass the requirement of syd-1. Liprin-α proteins are composed of coiled-coil-rich regions in the N-terminal half, which mediate interactions with adapter proteins at the presynaptic active zone, and three SAM domains in the C terminus, which bind proteins such as LAR receptor tyrosine phosphatase. To address the molecular mechanism by which SYD-2 activity is regulated, we performed structure-function studies. By monitoring the ability of SYD-2 transgenes to rescue syd-2(lf) and to suppress syd-1(lf) phenotypes in HSN neuron synapses, we identified the N-terminal half of SYD-2 as minimally required for rescuing syd-2(lf) phenotypes. A highly conserved short coiled-coil segment named Liprin Homology 1 (LH1) domain is both necessary and sufficient to suppress syd-1(lf) defects. We show that the LH1 domain forms a dimer and promotes further oligomerization and/or complex formation of SYD-2/Liprin-α proteins. The role of the LH1 domain in presynaptic assembly can be partially complemented by artificial dimerization. These findings suggest a model by which the self-assembly of SYD-2/Liprin-α proteins mediated by the coiled-coil LH1 domain is one of the key steps to the accumulation of presynaptic components at nascent synaptic junctions.
Mesh Terms:
Adaptor Proteins, Signal Transducing, Animals, Animals, Genetically Modified, Caenorhabditis elegans, Caenorhabditis elegans Proteins, Cell Line, Transformed, Cercopithecus aethiops, Gene Expression Regulation, Green Fluorescent Proteins, Humans, Motor Neurons, Mutation, Phosphoproteins, Presynaptic Terminals, Protein Structure, Tertiary, Synapses
Adaptor Proteins, Signal Transducing, Animals, Animals, Genetically Modified, Caenorhabditis elegans, Caenorhabditis elegans Proteins, Cell Line, Transformed, Cercopithecus aethiops, Gene Expression Regulation, Green Fluorescent Proteins, Humans, Motor Neurons, Mutation, Phosphoproteins, Presynaptic Terminals, Protein Structure, Tertiary, Synapses
J. Neurosci.
Date: Nov. 09, 2011
PubMed ID: 22072677
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