Selective transport of alpha-mannosidase by autophagic pathways: identification of a novel receptor, Atg34p.

In Saccharomyces cerevisiae, aminopeptidase I (Ape1p) and α-mannosidase (Ams1p) are known cargoes of selective autophagy. Atg19p has been identified as an Ape1p receptor and targets Ape1p to the preautophagosomal structure (PAS). Under nutrient-rich conditions, transport of Ams1p to the vacuole largely depends on Atg19p. Here, we show that Atg34p (Yol083wp), a homolog of Atg19p, is a receptor for Ams1p transport during autophagy. Atg34p interacted with Ams1p, Atg11p, and Atg8p using distinct domains. Homo-oligomerized Ams1p bound to the Ams1-binding domain of Atg34p; this binding was important for the formation of a higher order complex named the Ams1 complex. In the absence of the interaction of Atg34p with Atg8p, the Ams1 complex was targeted to the preautophagosomal structure but failed to transit to the vacuole, indicating that the interaction of Atg34p with Atg8p is crucial for the Ams1 complex to be enclosed by autophagosomes. Atg34p and Atg19p have similar domain structures and are important for Ams1p transport during autophagy.