title: Extraproteasomal Rpn10 restricts access of the polyubiquitin-binding protein Dsk2 to proteasome.
abstract: Polyubiquitin is a diverse signal both in terms of chain length and linkage type. Lysine 48-linked ubiquitin is essential for marking targets for proteasomal degradation, but the significance and relative abundance of different linkages remain ambiguous. Here we dissect the relationship of two proteasome-associated polyubiquitin-binding proteins, Rpn10 and Dsk2, and demonstrate how Rpn10 filters Dsk2 interactions, maintaining proper function of the ubiquitin-proteasome system. Using quantitative mass spectrometry of ubiquitin, we found that in S. cerevisiae under normal growth conditions the majority of conjugated ubiquitin was linked via lysine 48 and lysine 63. In contrast, upon DSK2 induction, conjugates accumulated primarily in the form of lysine 48 linkages correlating with impaired proteolysis and cytotoxicity. By restricting Dsk2 access to the proteasome, extraproteasomal Rpn10 was essential for alleviating the cellular stress associated with Dsk2. This work highlights the importance of polyubiquitin shuttles such as Rpn10 and Dsk2 in controlling the ubiquitin landscape.
authors.affiliation: Department of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel.
authors.forename: Yulia
authors.initials: Y
authors.lastname: Matiuhin
authors.forename: Donald S
authors.initials: DS
authors.lastname: Kirkpatrick
authors.forename: Inbal
authors.initials: I
authors.lastname: Ziv
authors.forename: Woong
authors.initials: W
authors.lastname: Kim
authors.forename: Arun
authors.initials: A
authors.lastname: Dakshinamurthy
authors.forename: Oded
authors.initials: O
authors.lastname: Kleifeld
authors.forename: Steven P
authors.initials: SP
authors.lastname: Gygi
authors.forename: Noa
authors.initials: N
authors.lastname: Reis
authors.forename: Michael H
authors.initials: MH
authors.lastname: Glickman
mesh_terms: D018797:Cell Cycle Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D025821:Polyubiquitin / Q000737:chemistry / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D011485:Protein Binding; D016601:RNA-Binding Proteins; D012441:Saccharomyces cerevisiae / Q000737:chemistry / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000378:metabolism; D025801:Ubiquitin / Q000302:isolation & purification / Q000378:metabolism*; D014452:Ubiquitins / Q000737:chemistry / Q000378:metabolism
chemical_list: D018797:Cell Cycle Proteins; C100415:DSK2 protein, S cerevisiae; C498506:PSMD4 protein, human; D016601:RNA-Binding Proteins; D029701:Saccharomyces cerevisiae Proteins; D025801:Ubiquitin; D014452:Ubiquitins; D025821:Polyubiquitin; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease