Aut5/Cvt17p, a Putative Lipase Essential for Disintegration of Autophagic Bodies inside the Vacuole

• DOI: 10.1128/jb.183.20.5942-5955.2001
• Publication Date: 2002-07-27T10:01:09Z
• Authors: Ulrike D. Epple; Ivet Suriapranata; Eeva-Liisa Eskelinen; Michael Thumm
• Keywords: 0301 basic medicine; Binding Sites; Membrane Glycoproteins; Saccharomyces cerevisiae Proteins; Sequence Homology, Amino Acid; Amino Acid Motifs; Genes, Fungal; Molecular Sequence Data; Autophagy-Related Proteins; Lipase; Saccharomyces cerevisiae; Phosphotransferases (Alcohol Group Acceptor); Protein Transport; 03 medical and health sciences; Vacuoles; Autophagy; Aspartic Acid Endopeptidases; Amino Acid Sequence; Microscopy, Immunoelectron; Carboxylic Ester Hydrolases; Glycoproteins; Half-Life

ABSTRACT Selective disintegration of membrane-enclosed autophagic bodies is a feature eukaryotic cells not studied in detail. Using Saccharomyces cerevisiae mutant defective autophagic-body breakdown, we identified and characterized Aut5p, glycosylated integral membrane protein. Site-directed mutagenesis demonstrated the relevance its putative lipase active-site motif for breakdown. aut5 Δ show reduced protein turnover during starvation are maturation proaminopeptidase I. Most recently, by means latter phenotype, Aut5p was independently as Cvt17p. In this study additionally checked effects on vacuolar acidification detected mature proteases, both which prerequisites lysis. Furthermore, biologically active hemagglutinin-tagged (Aut5-Ha) localizes to endoplasmic reticulum (nuclear envelope) targeted lumen independent autophagy. pep4 immunogold electron microscopy located Aut5-Ha at ∼50-nm-diameter intravacuolar vesicles. Characteristic missorting vps class E fab1 cells, affects multivesicular body (MVB) pathway, suggests targeting similar that MVB pathway. agreement with localization vesicles lack wild-type our pulse-chase experiments clearly indicated degradation 50 70 min half-life dependent proteinase A.