Resolving the molecular architecture of the photoreceptor active zone by 3D-MINFLUX

Authors

Grabner CP, Jansen I, Neef J, Weihs T, Schmidt R, Riedel D, Wurm CA, Moser T

Journal

Science Advances

Citation

Sci Adv. 2022, accepted.

Abstract

Cells assemble macromolecular complexes into scaffoldings that serve as substrates for catalytic processes. Years of molecular neurobiology indicate that neurotransmission depends on such optimization strategies. However, the molecular topography of the presynaptic Active Zone (AZ), where transmitter is released upon synaptic vesicle (SV) fusion, remains to be visualized. Therefore, we implemented MINFLUX optical nanoscopy to resolve the AZ of rod photoreceptors. This built on a novel sample immobilization technique that we name Heat Assisted Rapid Dehydration (HARD), wherein a thin layer of rod synaptic terminals (spherules) was transferred onto glass coverslips from fresh retinal slices. Ribbon-type rod AZs were readily immunolabeled and imaged in 3D with a precision of few nanometers. Our 3D-MINFLUX results indicate that the SV release site in rods is a molecular complex of bassoon−RIM2−ubMunc13-2−Cav1.4, which repeats longitudinally on both sides of the ribbon.

DOI

10.1101/2021.05.28.446138