Yeast Mon1p/Aut12p functions in vacuolar fusion of autophagosomes and cvt‐vesicles

Here we identify Mon1p as being essential for the cvt‐pathway and autophagy. Thus, mon1Δ cells are impaired in proaminopeptidase I maturation and homozygous diploid mon1Δ cells do not sporulate. Quantitative autophagy measurements suggest a complete autophagy block. The autophagosomal marker protein GFP‐Aut7p accumulates in mon1Δ cells at punctate structures outside the vacuole. Furthermore, proaminopeptidase I accumulates in mon1Δ cells in a proteinase‐protected form. Our data demonstrate that mon1Δ cells are defective in the fusion of cvt‐vesicles and autophagosomes with the vacuole. Consistent with this, GFP‐Mon1p localizes to the cytosol and to punctate structures within the cytosol.

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