The COP9 signalosome-like complex in S. cerevisiae and links to other PCI complexes.
The COP9 signalosome (CSN), the lid subcomplex of the proteasome and translational initiation factor 3 (eIF3) share structural similarities and are often referred to as the PCI family of complexes. In multicellular eukaryotes, the CSN is highly conserved as an 8-subunit complex but in Saccharomyces cerevisiae the complex is rather divergent. We further characterize the composition and properties of the CSN in budding yeast and its interactions with these related complexes. Using the generalized profile method we identified CSN candidates, four with PCI domains: Csn9, Csn10, Pci8/Csn11, and Csn12, and one with an MPN domain, Csn5/Rri1. These proteins and an additional interactor, Csi1, were tested for pairwise interactions by yeast two-hybrid and were found to form a cluster surrounding Csn12. Csn5 and Csn12 cofractionate in a complexed form with an apparent molecular weight of roughly 250kDa. However, Csn5 migrates as a monomer in Deltacsn12 supporting the pivotal role of Csn12 in stabilizing the complex. Confocal fluorescence microscopy detects GFP-tagged Csn5 preferentially in the nucleus, whereas in absence of Csn12, Csn10, Pci8/Csn11, or Csi1, Csn5 is delocalized throughout the cell, indicating that multiple subunits are required for nuclear localization of Csn5. Two CSN subunits, Csn9 and Csi1, interact with the proteasome lid subunit Rpn5. Pci8/Csn11 has previously been shown to interact with eIF3. Together, these results point to a network of interactions between these three structurally similar, yet functionally diverse, complexes.
Maytal-Kivity
Vered
V
Department of Biology and Institute for Catalysis Science and Technology (ICST), Technion-Israel Institute of Technology, 32000, Haifa, Israel.
Pick
Elah
E
Piran
Ron
R
Hofmann
Kay
K
Glickman
Michael H
MH
D000595:Amino Acid Sequence; D000075686:COP9 Signalosome Complex; D003546:Cysteine Endopeptidases / Q000235:genetics; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000235:genetics; D046912:Multiprotein Complexes; D010447:Peptide Hydrolases; D010802:Phylogeny; D046988:Proteasome Endopeptidase Complex; D011506:Proteins / Q000737:chemistry* / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000235:genetics; D004718:Saccharomycetales / Q000235:genetics*; D016415:Sequence Alignment; D017385:Sequence Homology; D014157:Transcription Factors / Q000737:chemistry* / Q000235:genetics; D025801:Ubiquitin / Q000235:genetics
D004268:DNA-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; D009097:Multienzyme Complexes; D046912:Multiprotein Complexes; D011506:Proteins; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D025801:Ubiquitin; D010447:Peptide Hydrolases; C501488:COPS5 protein, human; D000075686:COP9 Signalosome Complex; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex