title: USP14 deubiquitinates proteasome-bound substrates that are ubiquitinated at multiple sites.
abstract: USP14 is a major regulator of the proteasome and one of three proteasome-associated deubiquitinating enzymes. Its effects on protein turnover are substrate-specific, for unknown reasons. We report that USP14 shows a marked preference for ubiquitin-cyclin B conjugates that carry more than one ubiquitin modification or chain. This specificity is conserved from yeast to humans and is independent of chain linkage type. USP14 has been thought to cleave single ubiquitin groups from the distal tip of a chain, but we find that it removes chains from cyclin B en bloc, proceeding until a single chain remains. The suppression of degradation by USP14's catalytic activity reflects its capacity to act on a millisecond time scale, before the proteasome can initiate degradation of the substrate. In addition, single-molecule studies showed that the dwell time of ubiquitin conjugates at the proteasome was reduced by USP14-dependent deubiquitination. In summary, the specificity of the proteasome can be regulated by rapid ubiquitin chain removal, which resolves substrates based on a novel aspect of ubiquitin conjugate architecture.
authors.affiliation: Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, Massachusetts 02115, USA.
authors.forename: Byung-Hoon
authors.initials: BH
authors.lastname: Lee
authors.affiliation: Department of Systems Biology, Harvard Medical School, 200 Longwood Avenue, Boston, Massachusetts 02115, USA.
authors.forename: Ying
authors.initials: Y
authors.lastname: Lu
authors.affiliation: Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, Massachusetts 02115, USA.
authors.forename: Miguel A
authors.initials: MA
authors.lastname: Prado
authors.affiliation: Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, Massachusetts 02115, USA.
authors.forename: Yuan
authors.initials: Y
authors.lastname: Shi
authors.affiliation: Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, Massachusetts 02115, USA.
authors.forename: Geng
authors.initials: G
authors.lastname: Tian
authors.affiliation: Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, Massachusetts 02115, USA.|Life Sciences Institute, Zhejiang University, Hangzhou, 310058, China.
authors.forename: Shuangwu
authors.initials: S
authors.lastname: Sun
authors.affiliation: Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, Massachusetts 02115, USA.
authors.forename: Suzanne
authors.initials: S
authors.lastname: Elsasser
authors.affiliation: Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, Massachusetts 02115, USA.
authors.forename: Steven P
authors.initials: SP
authors.lastname: Gygi
authors.affiliation: Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, Massachusetts 02115, USA.
authors.forename: Randall W
authors.initials: RW
authors.lastname: King
authors.affiliation: Department of Cell Biology, Harvard Medical School, 240 Longwood Avenue, Boston, Massachusetts 02115, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Finley
mesh_terms: D055162:Biocatalysis; D019926:Cyclin B / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D008958:Models, Molecular; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D059748:Proteolysis; D013379:Substrate Specificity; D025801:Ubiquitin / Q000378:metabolism; D043222:Ubiquitin Thiolesterase / Q000378:metabolism*; D054875:Ubiquitination; D015003:Yeasts / Q000201:enzymology
chemical_list: D019926:Cyclin B; C509299:USP14 protein, human; D025801:Ubiquitin; D043222:Ubiquitin Thiolesterase; D046988:Proteasome Endopeptidase Complex