title: Atg19p ubiquitination and the cytoplasm to vacuole trafficking pathway in yeast.
abstract: The cytoplasm to vacuole (Cvt) trafficking pathway in S. cerevisiae is a constitutive biosynthetic pathway required for the transport of two vacuolar enzymes, aminopeptidase I (Ape1p) and alpha-mannosidase (Ams1p), to the vacuole. Ape1p and Ams1p bind to their receptor, Atg19p, in the cytosol to form a Cvt complex, which then associates with a membrane structure that envelops the complex before fusing with the vacuolar membrane. Ubiquitin-like modifications are required for both Cvt and macroautophagy, but no role for ubiquitin itself has been described. Here, we show that the deubiquitinating enzyme Ubp3p interacts with Atg19p. Moreover, Atg19p is ubiquitinated in vivo, and Atg19p-ubiquitin conjugates accumulate in cells lacking either Ubp3p or its cofactor, Bre5p. Deletion of UBP3 also leads to decreased targeting of Ape1p to the vacuole. Atg19p is ubiquitinated on two lysine residues, Lys(213) and Lys(216), which, when mutated, reduce the interaction of Atg19p with Ape1p. These results suggest that both ubiquitination and deubiquitination of Atg19p are required for its full function.
authors.affiliation: Department of Biology, University of Rochester, Rochester, New York 14627, USA.
authors.forename: Bonnie K
authors.initials: BK
authors.lastname: Baxter
authors.forename: Hagai
authors.initials: H
authors.lastname: Abeliovich
authors.forename: Xin
authors.initials: X
authors.lastname: Zhang
authors.forename: Aline G
authors.initials: AG
authors.lastname: Stirling
authors.forename: Alma L
authors.initials: AL
authors.lastname: Burlingame
authors.forename: David S
authors.initials: DS
authors.lastname: Goldfarb
mesh_terms: D000595:Amino Acid Sequence; D000626:Aminopeptidases / Q000378:metabolism; D000071183:Autophagy-Related Proteins; D001665:Binding Sites / Q000235:genetics; D001693:Biological Transport, Active; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism; D010450:Endopeptidases / Q000235:genetics / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020798:Two-Hybrid System Techniques; D025801:Ubiquitin / Q000378:metabolism; D014617:Vacuoles / Q000378:metabolism; D033921:Vesicular Transport Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D043323:alpha-Mannosidase / Q000378:metabolism
chemical_list: C434480:ATG19 protein, S cerevisiae; D000071183:Autophagy-Related Proteins; D002352:Carrier Proteins; D011956:Receptors, Cell Surface; D011993:Recombinant Fusion Proteins; D029701:Saccharomyces cerevisiae Proteins; D025801:Ubiquitin; D033921:Vesicular Transport Proteins; D043323:alpha-Mannosidase; D010450:Endopeptidases; D000626:Aminopeptidases; C019689:APE1 protein, S cerevisiae; C503886:Bre5 protein, S cerevisiae; C101111:UBP3 protein, S cerevisiae