Hrr25 phosphorylates the autophagic receptor Atg34 to promote vacuolar transport of α-mannosidase under nitrogen starvation conditions.

In Saccharomyces cerevisiae, under nitrogen-starvation conditions, the α-mannosidase Ams1 is recognized by the autophagic receptor Atg34 and transported into the vacuole, where it functions as an active enzyme. In this study, we identified Hrr25 as the kinase that phosphorylates Atg34 under these conditions. Hrr25-mediated phosphorylation does not affect the interaction of Atg34 with Ams1, but instead promotes Atg34 binding to the adaptor protein Atg11, which recruits the autophagy machinery to the Ams1-Atg34 complex, resulting in activation of the vacuolar transport of Ams1. Our findings reveal the regulatory mechanism of a biosynthetic pathway mediated by the autophagy machinery.