Molecular characterization of subunit 6 of the COP9 signalosome and its role in multifaceted developmental processes in Arabidopsis.
The COP9 signalosome is a highly conserved protein complex initially identified as a repressor of photomorphogenesis. Here, we report that subunit 6 of the Arabidopsis COP9 signalosome is encoded by a family of two genes (CSN6A and CSN6B) located on chromosomes V and IV, respectively. The CSN6A and CSN6B proteins share 87% amino acid identity and contain a MPR1p and PAD1p N-terminal (MPN) domain at the N-terminal region. The CSN6 proteins share homology with CSN5 and belong to the Mov34 superfamily of proteins. CSN6 proteins present only in the complex form and coimmunoprecipitate with other known subunits of the COP9 signalosome. Partial loss-of-function strains of the COP9 signalosome created by antisense and cosuppression with CSN6A exhibit diverse developmental defects, including homeotic organ transformation, symmetric body organization, and organ boundary definition. Protein blot analysis revealed that the defective plants accumulate significant amounts of ubiquitinated proteins, supporting the conclusion that the COP9 signalosome regulates multifaceted developmental processes through its involvement in ubiquitin/proteasome-mediated protein degradation.
Peng
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Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, Connecticut 06520-8104, USA.
Serino
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Deng
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XW
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000145:classification / Q000235:genetics*; D029681:Arabidopsis Proteins; D000075686:COP9 Signalosome Complex; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics; D006801:Humans; D008969:Molecular Sequence Data; D005810:Multigene Family; D046912:Multiprotein Complexes; D010447:Peptide Hydrolases; D010641:Phenotype; D010802:Phylogeny; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics; D011494:Protein Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D021122:Protein Subunits; D011506:Proteins / Q000235:genetics*; D012441:Saccharomyces cerevisiae / Q000235:genetics; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014170:Transformation, Genetic
D029681:Arabidopsis Proteins; C445070:CSN6B protein, Arabidopsis; D018076:DNA, Complementary; D046912:Multiprotein Complexes; D010940:Plant Proteins; D021122:Protein Subunits; D011506:Proteins; D011494:Protein Kinases; D010447:Peptide Hydrolases; D000075686:COP9 Signalosome Complex