title: Structural and biochemical characterization of the Cop9 signalosome CSN5/CSN6 heterodimer.
abstract: The Cop9 signalosome complex (CSN) regulates the functional cycle of the major E3 ubiquitin ligase family, the cullin RING E3 ubiquitin ligases (CRLs). Activated CRLs are covalently modified by the ubiquitin-like protein Nedd8 (neural precursor cell expressed developmentally down-regulated protein 8). CSN serves an essential role in myriad cellular processes by reversing this modification through the isopeptidase activity of its CSN5 subunit. CSN5 alone is inactive due to an auto-inhibited conformation of its catalytic domain. Here we report the molecular basis of CSN5 catalytic domain activation and unravel a molecular hierarchy in CSN deneddylation activity. The association of CSN5 and CSN6 MPN (for Mpr1/Pad1 N-terminal) domains activates its isopeptidase activity. The CSN5/CSN6 module, however, is inefficient in CRL deneddylation, indicating a requirement of further elements in this reaction such as other CSN subunits. A hybrid molecular model of CSN5/CSN6 provides a structural framework to explain these functional observations. Docking this model into a published CSN electron density map and using distance constraints obtained from cross-linking coupled to mass-spectrometry, we find that the C-termini of the CSN subunits could form a helical bundle in the centre of the structure. They likely play a key scaffolding role in the spatial organization of CSN and precise positioning of the dimeric MPN catalytic core.
authors.affiliation: Centre de Biochimie Structurale, Unité Mixte de Recherche (UMR) 5048, Centre National de Recherche Scientifique (CNRS), Université Montpellier 1 (UM1), Université Montpellier 2 (UM2), Montpellier, France; Institut national de la santé et de la recherche médicale (INSERM) U1054, Paris, France.
authors.forename: Melissa
authors.initials: M
authors.lastname: Birol
authors.affiliation: ETH Zurich, Department of Biology, Institute of Biochemistry, Zurich, Switzerland.
authors.forename: Radoslav Ivanov
authors.initials: RI
authors.lastname: Enchev
authors.affiliation: Centre de Biochimie Structurale, Unité Mixte de Recherche (UMR) 5048, Centre National de Recherche Scientifique (CNRS), Université Montpellier 1 (UM1), Université Montpellier 2 (UM2), Montpellier, France; Institut national de la santé et de la recherche médicale (INSERM) U1054, Paris, France.
authors.forename: André
authors.initials: A
authors.lastname: Padilla
authors.affiliation: ETH Zurich, Department of Biology, Institute of Molecular Systems Biology, Zurich, Switzerland.
authors.forename: Florian
authors.initials: F
authors.lastname: Stengel
authors.affiliation: ETH Zurich, Department of Biology, Institute of Molecular Systems Biology, Zurich, Switzerland; Faculty of Science, University of Zurich, Zurich, Switzerland.
authors.forename: Ruedi
authors.initials: R
authors.lastname: Aebersold
authors.affiliation: Centre de Recherche en Cancérologie de Marseille, Centre de Biochimie Structurale, Unité Mixte de Recherche (UMR) 7258, Institut national de la santé et de la recherche médicale (INSERM) U1068, Institut Paoli-Calmettes, Aix-Marseille Université UM105, Marseille, France.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Betzi
authors.affiliation: Centre de Biochimie Structurale, Unité Mixte de Recherche (UMR) 5048, Centre National de Recherche Scientifique (CNRS), Université Montpellier 1 (UM1), Université Montpellier 2 (UM2), Montpellier, France; Institut national de la santé et de la recherche médicale (INSERM) U1054, Paris, France.
authors.forename: Yinshan
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Centre de Biochimie Structurale, Unité Mixte de Recherche (UMR) 5048, Centre National de Recherche Scientifique (CNRS), Université Montpellier 1 (UM1), Université Montpellier 2 (UM2), Montpellier, France; Institut national de la santé et de la recherche médicale (INSERM) U1054, Paris, France.
authors.forename: François
authors.initials: F
authors.lastname: Hoh
authors.affiliation: ETH Zurich, Department of Biology, Institute of Biochemistry, Zurich, Switzerland.
authors.forename: Matthias
authors.initials: M
authors.lastname: Peter
authors.affiliation: Centre de Biochimie Structurale, Unité Mixte de Recherche (UMR) 5048, Centre National de Recherche Scientifique (CNRS), Université Montpellier 1 (UM1), Université Montpellier 2 (UM2), Montpellier, France; Institut national de la santé et de la recherche médicale (INSERM) U1054, Paris, France.
authors.forename: Christian
authors.initials: C
authors.lastname: Dumas
authors.affiliation: Centre de Biochimie Structurale, Unité Mixte de Recherche (UMR) 5048, Centre National de Recherche Scientifique (CNRS), Université Montpellier 1 (UM1), Université Montpellier 2 (UM2), Montpellier, France; Institut national de la santé et de la recherche médicale (INSERM) U1054, Paris, France.
authors.forename: Aude
authors.initials: A
authors.lastname: Echalier
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000737:chemistry* / Q000378:metabolism; D000075686:COP9 Signalosome Complex; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D046912:Multiprotein Complexes / Q000737:chemistry* / Q000378:metabolism; D000075687:NEDD8 Protein; D010447:Peptide Hydrolases / Q000737:chemistry* / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D054730:Protein Interaction Domains and Motifs; D055503:Protein Multimerization; D021122:Protein Subunits; D014452:Ubiquitins / Q000378:metabolism
chemical_list: D048868:Adaptor Proteins, Signal Transducing; C470634:COPS6 protein, human; D047908:Intracellular Signaling Peptides and Proteins; D046912:Multiprotein Complexes; D000075687:NEDD8 Protein; C082860:NEDD8 protein, human; D021122:Protein Subunits; D014452:Ubiquitins; D010447:Peptide Hydrolases; C501488:COPS5 protein, human; D000075686:COP9 Signalosome Complex