title: Open-gate mutants of the mammalian proteasome show enhanced ubiquitin-conjugate degradation.
abstract: When in the closed form, the substrate translocation channel of the proteasome core particle (CP) is blocked by the convergent N termini of α-subunits. To probe the role of channel gating in mammalian proteasomes, we deleted the N-terminal tail of α3; the resulting α3ΔN proteasomes are intact but hyperactive in the hydrolysis of fluorogenic peptide substrates and the degradation of polyubiquitinated proteins. Cells expressing the hyperactive proteasomes show markedly elevated degradation of many established proteasome substrates and resistance to oxidative stress. Multiplexed quantitative proteomics revealed ∼ 200 proteins with reduced levels in the mutant cells. Potentially toxic proteins such as tau exhibit reduced accumulation and aggregate formation. These data demonstrate that the CP gate is a key negative regulator of proteasome function in mammals, and that opening the CP gate may be an effective strategy to increase proteasome activity and reduce levels of toxic proteins in cells.
authors.affiliation: Department of Biomedical Sciences, Seoul National University Graduate School, Seoul 03080, Korea.|Department of Biochemistry and Molecular Biology, Seoul National University College of Medicine, Seoul 03080, Korea.
authors.forename: Won Hoon
authors.initials: WH
authors.lastname: Choi
authors.affiliation: Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA.
authors.forename: Stefanie A H
authors.initials: SA
authors.lastname: de Poot
authors.affiliation: Department of Biochemistry and Molecular Biology, Seoul National University College of Medicine, Seoul 03080, Korea.
authors.forename: Jung Hoon
authors.initials: JH
authors.lastname: Lee
authors.affiliation: Department of Biomedical Sciences, Seoul National University Graduate School, Seoul 03080, Korea.
authors.forename: Ji Hyeon
authors.initials: JH
authors.lastname: Kim
authors.affiliation: Department of Biochemistry and Molecular Biology, Seoul National University College of Medicine, Seoul 03080, Korea.
authors.forename: Dong Hoon
authors.initials: DH
authors.lastname: Han
authors.affiliation: Center for Neuro-Medicine, Korea Institute of Science and Technology (KIST), Seoul 02790, Korea.
authors.forename: Yun Kyung
authors.initials: YK
authors.lastname: Kim
authors.affiliation: Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Finley
authors.affiliation: Department of Biomedical Sciences, Seoul National University Graduate School, Seoul 03080, Korea.|Department of Biochemistry and Molecular Biology, Seoul National University College of Medicine, Seoul 03080, Korea.|Neuroscience Research Institute, Seoul National University College of Medicine, Seoul 03080, Korea.
authors.forename: Min Jae
authors.identifier: http://orcid.org/0000-0002-3252-6467
authors.initials: MJ
authors.lastname: Lee
mesh_terms: D002460:Cell Line; D006801:Humans; D006868:Hydrolysis; D009154:Mutation; D046988:Proteasome Endopeptidase Complex / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D059748:Proteolysis; D025801:Ubiquitin / Q000378:metabolism*
chemical_list: D011506:Proteins; D025801:Ubiquitin; D046988:Proteasome Endopeptidase Complex