The nanoscale mobility of calcium channels is driven by readily releasable synaptic vesicles to support precise neurotransmission in live C. elegans

Abstract

Precise neurotransmission requires voltage-gated calcium channels (VGCCs) to be tightly coupled with synaptic vesicles (SVs) at active zones (AZs). As VGCCs are mobile in the fluid presynaptic membrane, it remained unclear how they spatiotemporally align with SVs for reliable synaptic release. Using super-resolution imaging and single-molecule tracking in C. elegans, we report that two diffusive behaviors of N-type VGCCs at AZs are governed by primed SVs via distinct mechanisms. VGCCs diffuse slowly in multiple nanodomains ([~]100 nm) that spatially correlate with UNC-10/RIM, and the channels mobility and nanodomain numbers are coupled to SNAREs assembly and SV priming levels via RAB-3/UNC-10/UNC-13L tripartite complexes. Outside nanodomains, a faster mobility of VGCCs and their AZ distribution scale with UNC-13S-mediated priming under an antagonistic regulation by UNC-10 and TOM-1/Tomosyn. These findings reveal unexpected mechanisms whereby pools of readily releasable SVs actively control the nanoscale mobility and nanodomain organization of VGCCs to support precise neurotransmission.