Lap3 is a selective target of autophagy in yeast, Saccharomyces cerevisiae.
Autophagy is a primarily non-selective degradation system of cytoplasmic constituents in lysosomes/vacuoles during starvation. In yeast, autophagy is also involved in the selective transport of Ape1, a vacuolar hydrolase, as a biosynthetic route. Ald6, a soluble cytoplasmic enzyme, is preferentially eliminated from cytoplasm via autophagy. However, little is known about the mechanisms of Ald6 targeting to autophagosomes. Here, we show that Lap3, a soluble cytosolic cysteine protease, is spatially associated with Ape1 and selectively transported to the vacuole during nitrogen starvation. The rate of Lap3 transport is much higher than that of Ald6 and is similar to that of Ape1. Moreover, ATG11 and ATG19, essential factors for Ape1 transport, are important for Lap3 transport. Most Lap3 is degraded within a couple of hours in the vacuole in contrast to Ape1; therefore, we conclude that the machinery required for Ape1 biosynthesis is used for selective degradation of Lap3.
Kageyama
Takuya
T
Division of Molecular Cell Biology, National Institute for Basic Biology, Okazaki 444-8585, Japan.
Suzuki
Kuninori
K
Ohsumi
Yoshinori
Y
D000626:Aminopeptidases / Q000235:genetics / Q000378:metabolism*; D001343:Autophagy; D000071183:Autophagy-Related Proteins; D003546:Cysteine Endopeptidases / Q000235:genetics / Q000378:metabolism*; D057056:Cysteine Proteases; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D009584:Nitrogen / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism; D021381:Protein Transport; D011956:Receptors, Cell Surface / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000502:physiology* / Q000648:ultrastructure; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D014617:Vacuoles / Q000201:enzymology; D033921:Vesicular Transport Proteins / Q000378:metabolism
C434480:ATG19 protein, S cerevisiae; D000071183:Autophagy-Related Proteins; D004268:DNA-Binding Proteins; D011956:Receptors, Cell Surface; D029701:Saccharomyces cerevisiae Proteins; D033921:Vesicular Transport Proteins; D011494:Protein Kinases; C477823:ATG1 protein, S cerevisiae; D057056:Cysteine Proteases; D000626:Aminopeptidases; C019689:APE1 protein, S cerevisiae; D003546:Cysteine Endopeptidases; C077486:LAP3 protein, S cerevisiae; D009584:Nitrogen