title: The organization of a CSN5-containing subcomplex of the COP9 signalosome.
abstract: The COP9 signalosome (CSN) is an evolutionarily conserved multi-protein complex that interfaces with the ubiquitin-proteasome pathway and plays critical developmental roles in both animals and plants. Although some subunits are present only in an ∼320-kDa complex-dependent form, other subunits are also detected in configurations distinct from the 8-subunit holocomplex. To date, the only known biochemical activity intrinsic to the complex, deneddylation of the Cullin subunits from Cullin-RING ubiquitin ligases, is assigned to CSN5. As an essential step to understanding the structure and assembly of a CSN5-containing subcomplex of the CSN, we reconstituted a CSN4-5-6-7 subcomplex. The core of the subcomplex is based on a stable heterotrimeric association of CSN7, CSN4, and CSN6, requiring coexpression in a bacterial reconstitution system. To this heterotrimer, we could then add CSN5 in vitro to reconstitute a quaternary complex. Using biochemical and biophysical methods, we identified pairwise and combinatorial interactions necessary for the formation of the CSN4-5-6-7 subcomplex. The subcomplex is stabilized by three types of interactions: MPN-MPN between CSN5 and CSN6, PCI-PCI between CSN4 and CSN7, and interactions mediated through the CSN6 C terminus with CSN4 and CSN7. CSN8 was also found to interact with the CSN4-6-7 core. These data provide a strong framework for further investigation of the organization and assembly of this pivotal regulatory complex.
authors.affiliation: Department of Molecular Biology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv 69978, Israel.
authors.forename: Giri Gowda
authors.initials: GG
authors.lastname: Kotiguda
authors.forename: Dahlia
authors.initials: D
authors.lastname: Weinberg
authors.forename: Moshe
authors.initials: M
authors.lastname: Dessau
authors.forename: Chiara
authors.initials: C
authors.lastname: Salvi
authors.forename: Giovanna
authors.initials: G
authors.lastname: Serino
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Chamovitz
authors.forename: Joel A
authors.initials: JA
authors.lastname: Hirsch
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D000075686:COP9 Signalosome Complex; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism*; D010447:Peptide Hydrolases / Q000235:genetics / Q000378:metabolism*; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000235:genetics / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D047908:Intracellular Signaling Peptides and Proteins; D046912:Multiprotein Complexes; D021122:Protein Subunits; D010447:Peptide Hydrolases; D000075686:COP9 Signalosome Complex