Atg36: the Saccharomyces cerevisiae receptor for pexophagy

Eukaryotic cells adapt their organelle composition and abundance according to environmental conditions. Analysis of the peroxisomal membrane protein Pex3 has revealed that this protein plays a crucial role in peroxisome maintenance as it is required for peroxisome formation, segregation and breakdown. Although its function in peroxisome formation and segregation was known to involve its recruitment to the peroxisomal membrane of factors specific for these processes, the role of Pex3 in peroxisome breakdown was unclear until our recent identification of Atg36 as a novel Saccharomyces cerevisiae Pex3-interacting protein. Atg36 is recruited to peroxisomes by Pex3 and is required specifically for pexophagy. Atg36 is distinct from Atg30, the pexophagy receptor identified in Pichia pastoris. Atg36 interacts with Atg11 in vivo, and to a lesser extent with Atg8. These latter proteins link autophagic cargo receptors to the core autophagy machinery. Like other autophagic cargo receptors, Atg36 is a suicide receptor and is broken down in the vacuole together with its cargo. Unlike other cargo receptors, the interaction between Atg36 and Atg8 does not seem to be direct. Our recent findings suggest that Atg36 is a novel pexophagy receptor that may target peroxisomes for degradation via a noncanonical mechanism.