title: Definitive evidence for Ufd2-catalyzed elongation of the ubiquitin chain through Lys48 linkage.
abstract: Saccharomyces cerevisiae Ufd2 is a ubiquitin chain elongation factor in the ubiquitin fusion degradation (UFD) pathway and functions in stress tolerance. A recent study has suggested that the mammalian Ufd2 homologue UFD2a catalyzes formation of Lys27- and Lys33-linked polyubiquitin chains rather than the Lys48-linked chain, but the linkage type of the polyubiquitin chain formed by yeast Ufd2 remains unclear. To determine the property of Ufd2, we reconstituted the UFD pathway using purified enzymes from yeast. Direct determination of the ubiquitin chain linkage type in polyubiquitinated UFD substrates by MALDI-TOF mass spectrometry revealed that Ufd2 catalyzes elongation of the ubiquitin chain through Lys48 linkage.
authors.affiliation: Department of Biochemistry, Graduate School of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Saeki
authors.forename: Yoko
authors.initials: Y
authors.lastname: Tayama
authors.forename: Akio
authors.initials: A
authors.lastname: Toh-e
authors.forename: Hideyoshi
authors.initials: H
authors.lastname: Yokosawa
mesh_terms: D001665:Binding Sites; D002384:Catalysis; D008239:Lysine / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D013329:Structure-Activity Relationship; D025801:Ubiquitin / Q000737:chemistry* / Q000378:metabolism*; D044763:Ubiquitin-Conjugating Enzymes
chemical_list: D029701:Saccharomyces cerevisiae Proteins; D025801:Ubiquitin; D044763:Ubiquitin-Conjugating Enzymes; C114683:UFD2 protein, S cerevisiae; D008239:Lysine