Autophagy and the cytoplasm to vacuole targeting pathway both require Aut10p

We here report the identification of AUT10 as a novel gene required for both the cytoplasm to vacuole targeting of proaminopeptidase I and starvation-induced autophagy. aut10Δ cells are impaired in maturation of proaminopeptidase I under starvation and non-starvation conditions. A lack of Aut10p causes a defect in autophagy prior to vacuolar uptake of autophagosomes. Homozygous aut10Δ diploids do not sporulate. Vacuolar acidification indicated by accumulation of quinacrine is normal in aut10Δ cells and mature vacuolar proteinases are present. A biologically active Ha-tagged Aut10p, chromosomally expressed from its endogenous promoter, localizes in indirect immunofluorescence microscopy in the cytosol and on granulated structures, which appear clustered around the vacuolar membrane. This localization differs from known autophagy proteins.