Roles of Pichia pastoris Uvrag in vacuolar protein sorting and the phosphatidylinositol 3-kinase complex in phagophore elongation in autophagy pathways.
Although it has been established that Atg6/Beclin 1, the phosphatidylinositol 3-kinase (PI3K) Vps34, and associated proteins have direct or indirect roles in autophagic pathways in both mammals and yeasts, the elucidation of these roles and the proteins required for them is ongoing. The involvement of the Beclin 1-binding protein, UVRAG, has been a particular source of disagreement. We found that PpAtg6 is required for all autophagic pathways that have been identified in the yeast Pichia pastoris, as well as for the carboxypeptidase Y (PpCPY) vacuolar protein sorting pathway. We localized PpAtg6 to the phagophore assembly site (PAS) and observed its continued presence at that site as the isolation membrane grew from it and matured into a pexophagosome. PpUvrag, however, was required for proper PpCPY sorting, but not for any autophagic pathway. Rather, the defects in all autophagic pathways observed when PpUvrag was overexpressed support its presence in a complex that competes with the PI3K complex required for autophagy.
Farré
Jean-Claude
JC
Section of Molecular Biology, Division of Biological Sciences, University California, San Diego, CA, USA.
Mathewson
Richard D
RD
Manjithaya
Ravi
R
Subramani
Suresh
S
D033942:Adaptor Proteins, Vesicular Transport / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D000595:Amino Acid Sequence; D001343:Autophagy / Q000235:genetics / Q000502:physiology*; D056827:Endosomal Sorting Complexes Required for Transport / Q000378:metabolism* / Q000502:physiology; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D015966:Gene Expression Regulation, Fungal; D008954:Models, Biological; D008969:Molecular Sequence Data; D030781:Organisms, Genetically Modified; D010588:Phagosomes / Q000235:genetics / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism / Q000502:physiology*; D010843:Pichia / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology; D014018:Tissue Distribution; D025521:Tumor Suppressor Proteins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology*
D033942:Adaptor Proteins, Vesicular Transport; D056827:Endosomal Sorting Complexes Required for Transport; D005656:Fungal Proteins; D025521:Tumor Suppressor Proteins; D019869:Phosphatidylinositol 3-Kinases