Premium
Higher‐order assemblies of oligomeric cargo receptor complexes form the membrane scaffold of the Cvt vesicle
Author(s) -
Bertipaglia Chiara,
Schneider Sarah,
Jakobi Arjen J,
Tarafder Abul K,
Bykov Yury S,
Picco Andrea,
Kukulski Wanda,
Kosinski Jan,
Hagen Wim JH,
Ravichandran Arvind C,
Wilmanns Matthias,
Kaksonen Marko,
Briggs John AG,
Sachse Carsten
Publication year - 2016
Publication title -
embo reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.584
H-Index - 184
eISSN - 1469-3178
pISSN - 1469-221X
DOI - 10.15252/embr.201541960
Subject(s) - chemistry , vesicle , scaffold , microbiology and biotechnology , biophysics , scaffold protein , membrane , order (exchange) , receptor , biochemistry , biology , business , signal transduction , computer science , finance , database
Selective autophagy is the mechanism by which large cargos are specifically sequestered for degradation. The structural details of cargo and receptor assembly giving rise to autophagic vesicles remain to be elucidated. We utilize the yeast cytoplasm‐to‐vacuole targeting (Cvt) pathway, a prototype of selective autophagy, together with a multi‐scale analysis approach to study the molecular structure of Cvt vesicles. We report the oligomeric nature of the major Cvt cargo Ape1 with a combined 2.8 Å X‐ray and negative stain EM structure, as well as the secondary cargo Ams1 with a 6.3 Å cryo‐ EM structure. We show that the major dodecameric cargo prApe1 exhibits a tendency to form higher‐order chain structures that are broken upon interaction with the receptor Atg19 in vitro . The stoichiometry of these cargo–receptor complexes is key to maintaining the size of the Cvt aggregate in vivo . Using correlative light and electron microscopy, we further visualize key stages of Cvt vesicle biogenesis. Our findings suggest that Atg19 interaction limits Ape1 aggregate size while serving as a vehicle for vacuolar delivery of tetrameric Ams1.