title: Endoproteolytic activity of the proteasome.
abstract: The proteasome plays a central role in the degradation of regulatory and misfolded proteins. Current models suggest that substrates access the internal catalytic sites by processively threading their termini through the gated substrate channel. Here, we found that latent (closed) and activated (open) proteasomes degraded two natively disordered substrates at internal peptide bonds even when they lacked accessible termini, suggesting that these substrates themselves promoted gating of the proteasome. This endoproteolysis provides a molecular mechanism for regulated release of transcription factors from inactive precursors as well as a means of accessing internal folding defects of misfolded multidomain proteins.
authors.affiliation: Department of Physiology, University of Texas Southwestern Medical Center at Dallas, Dallas, TX 75390, USA.
authors.forename: Chang-Wei
authors.initials: CW
authors.lastname: Liu
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Corboy
authors.forename: George N
authors.initials: GN
authors.lastname: DeMartino
authors.forename: Philip J
authors.initials: PJ
authors.lastname: Thomas
mesh_terms: D000595:Amino Acid Sequence; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000737:chemistry / Q000378:metabolism*; D003500:Cyclization; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D049452:Green Fluorescent Proteins; D007976:Leupeptins / Q000494:pharmacology; D008164:Luminescent Proteins / Q000737:chemistry / Q000378:metabolism; D009097:Multienzyme Complexes / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000378:metabolism*; D010447:Peptide Hydrolases / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex; D011487:Protein Conformation; D017510:Protein Folding; D019154:Protein Splicing; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D051843:Synucleins
chemical_list: D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D015853:Cysteine Proteinase Inhibitors; D007976:Leupeptins; D008164:Luminescent Proteins; D009097:Multienzyme Complexes; D009419:Nerve Tissue Proteins; D011993:Recombinant Fusion Proteins; D051843:Synucleins; D049452:Green Fluorescent Proteins; D010447:Peptide Hydrolases; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde