Conservation of the COP9/signalosome in budding yeast.
BACKGROUND
The COP9/signalosome (CSN), a multiprotein complex consisting of eight subunits, is implicated in a wide variety of regulatory processes including cell cycle control, signal transduction, transcriptional activation, and plant photomorphogenesis. Some of these functions have been linked to CSN-associated enzymes, including kinases and an activity that removes the ubiquitin-like protein NEDD8/Rub1p from the cullin subunit of E3 ligases. CSN is highly conserved across species from fission yeast to humans, but sequence comparison has failed to identify the complex in budding yeast, except for a putative CSN5 subunit called Rri1p.


RESULTS
We show that disruption of four budding yeast genes, PCI8 and three previously uncharacterized ORFs, which encode proteins interacting with Rrr1p/Csn5p, each results in the accumulation of the cullin Cdc53p exclusively in the Rub1p-modified state. This phenotype, which resembles that of fission yeast csn mutants, is due to a biochemical defect in deneddylation that is complemented by wild-type cell lysate and by purified human CSN in vitro. Although three of the four genes encode proteins with PCI domains conserved in metazoan CSN proteins, their disruption does not confer the DNA damage sensitivity described in some fission yeast csn mutants.


CONCLUSIONS
Our studies present unexpected evidence for the conservation of a functional homologue of the metazoan CSN, which mediates control of cullin neddylation in budding yeast.
Department of Cancer Cell Biology, Harvard School of Public Health, Boston, USA. swee@hsph.harvard.edu
Susan
S
Wee
Bettina
B
Hetfeld
Wolfgang
W
Dubiel
Dieter A
DA
Wolf
D000818:Animals; D001665:Binding Sites / Q000235:genetics; D000075686:COP9 Signalosome Complex; D016213:Cyclins / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D019143:Evolution, Molecular; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D005816:Genetic Complementation Test; D006801:Humans; D046912:Multiprotein Complexes; D009154:Mutation; D051738:Origin Recognition Complex; D010447:Peptide Hydrolases; D011485:Protein Binding; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins; D004718:Saccharomycetales / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D020798:Two-Hybrid System Techniques; D014452:Ubiquitins
D016213:Cyclins; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D046912:Multiprotein Complexes; D051738:Origin Recognition Complex; C066824:PHO80 protein, S cerevisiae; D011506:Proteins; C111706:RUB1 protein, S cerevisiae; D012097:Repressor Proteins; D029701:Saccharomyces cerevisiae Proteins; D014452:Ubiquitins; D010447:Peptide Hydrolases; D000075686:COP9 Signalosome Complex