Autophagy is the major pathway for the delivery of cytoplasmic material to the vacuole or lysosome. Selective autophagy is mediated by cargo receptors, which link the cargo to the scaffold protein Atg11 and to Atg8 family proteins on the forming autophagosomal membrane. We show that the essential kinase Hrr25 activates the cargo receptor Atg19 by phosphorylation, which is required to link cargo to the Atg11 scaffold, allowing selective autophagy to proceed. We also find that the Atg34 cargo receptor is regulated in a similar manner, suggesting a conserved mechanism.
Autophagy cargo receptors recruit the material to be degraded to Atg11 and Atg8 proteins on the growing phagophore. Here, Hrr25 kinase is shown to enable this process by directly activating selective autophagy receptor Atg19.
- The caseine kinase 1 homologue Hrr25 phosphorylates the cargo receptor Atg19 in its Atg11 binding region on serine residues 390, 391 and 396.
- These phosphorylation events are required for Atg19 binding to Atg11 and the progression of the Cvt pathway.
- The cargo receptor Atg34 requires similar phosphorylation in its Atg11 binding region for binding to Atg11.