The breakdown of autophagic vesicles inside the vacuole depends on Aut4p.
Autophagy is a degradative transport pathway that delivers cytosolic proteins to the lysosome (vacuole). Cytosolic proteins appear inside the vacuole enclosed in autophagic vesicles. These autophagic vesicles are broken down in the vacuole together with their cytosolic content. The breakdown of vesicular transport intermediates is a unique feature of autophagy. We here identify Aut4p, a component essential for the disintegration of autophagic vesicles, inside the vacuole of S. cerevisiae cells. Aut4p is a putative integral membrane protein with limited homologies to permeases. Chromosomal deletion of AUT4 has no obvious influence on growth, vacuolar acidification and the activities of vacuolar proteinases. Like proteinase B-deficient cells, aut4-deleted cells show a partial reduction in total protein breakdown during nitrogen starvation. A biologically active fusion protein of Aut4p and the green fluorescent protein is visualized at the vacuolar membrane and in punctate structures attached to the vacuole.
Suriapranata
I
I
Institut fuer Biochemie, Universitaet Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart.
Epple
U D
UD
Bernreuther
D
D
Bredschneider
M
M
Sovarasteanu
K
K
Thumm
M
M
D000595:Amino Acid Sequence; D001343:Autophagy; D000071183:Autophagy-Related Proteins; D001483:Base Sequence; D015825:Chromosomes, Fungal; D003600:Cytosol / Q000378:metabolism; D010450:Endopeptidases / Q000378:metabolism; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009838:Oligodeoxyribonucleotides; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000502:physiology* / Q000648:ultrastructure; D029701:Saccharomyces cerevisiae Proteins; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014617:Vacuoles / Q000502:physiology* / Q000648:ultrastructure
C418505:ATG22 protein, S cerevisiae; D000071183:Autophagy-Related Proteins; D005656:Fungal Proteins; D008565:Membrane Proteins; D009838:Oligodeoxyribonucleotides; D029701:Saccharomyces cerevisiae Proteins; D010450:Endopeptidases