title: Multiple ubiquitin ligase-mediated processes require COP9 signalosome and AXR1 function.
abstract: The COP9 signalosome (CSN) is an evolutionarily conserved multiprotein complex that mediates the repression of photomorphogenesis in the dark in Arabidopsis through the degradation of transcription factors such as HY5 and HYH. CSN-mediated HY5 and HYH degradation also requires the activity of the putative E3 ubiquitin ligase (E3) component COP1 and the E2-conjugating enzyme variant COP10. Recently, it was shown that CSN also is required for auxin responses mediated by the SCF-type E3 SCF(TIR1). To determine whether Arabidopsis CSN is required for E3-mediated processes in a more general manner, we generated plants with reduced E3 function by suppressing AtRBX1, an essential core subunit of SCF-type E3s. We observed that AtRBX1 transgenic plants share multiple phenotypes with CSN reduced-function plants, such as morphological defects and reduced responses to auxin, jasmonic acid, and cold stress, suggesting that CSN is required for multiple AtRBX1-mediated processes. Furthermore, we observed that mutants with defects in AXR1, a protein that had been described only as a regulator of SCF(TIR1) function, also is required for other E3-mediated processes and for the COP1/COP10/CSN-mediated repression of photomorphogenesis in the dark. We conclude that CSN and AXR1 are of general importance for different pathways that are controlled by E3-mediated protein degradation.
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism; D000075686:COP9 Signalosome Complex; D003080:Cold Temperature; D003517:Cyclopentanes / Q000494:pharmacology; D003624:Darkness; D019143:Evolution, Molecular; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D006133:Growth Substances / Q000235:genetics* / Q000378:metabolism; D007210:Indoleacetic Acids / Q000494:pharmacology; D008025:Ligases / Q000235:genetics* / Q000378:metabolism; D008027:Light; D008969:Molecular Sequence Data; D046912:Multiprotein Complexes; D009687:Nuclear Proteins; D054883:Oxylipins; D010447:Peptide Hydrolases; D010453:Peptide Synthases / Q000235:genetics / Q000378:metabolism; D010641:Phenotype; D010802:Phylogeny; D010937:Plant Growth Regulators / Q000494:pharmacology; D030821:Plants, Genetically Modified; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D044843:SKP Cullin F-Box Protein Ligases; D014157:Transcription Factors / Q000378:metabolism; D044763:Ubiquitin-Conjugating Enzymes; D044767:Ubiquitin-Protein Ligases; D014452:Ubiquitins / Q000235:genetics / Q000378:metabolism
chemical_list: C081977:AXR1 protein, Arabidopsis; D029681:Arabidopsis Proteins; C445070:CSN6B protein, Arabidopsis; D003517:Cyclopentanes; D006133:Growth Substances; D007210:Indoleacetic Acids; D046912:Multiprotein Complexes; D009687:Nuclear Proteins; D054883:Oxylipins; D010937:Plant Growth Regulators; D011506:Proteins; D014157:Transcription Factors; D014452:Ubiquitins; C011006:jasmonic acid; C450820:COP10 protein, Arabidopsis; D044763:Ubiquitin-Conjugating Enzymes; D044843:SKP Cullin F-Box Protein Ligases; D044767:Ubiquitin-Protein Ligases; D011494:Protein Kinases; D010447:Peptide Hydrolases; D000075686:COP9 Signalosome Complex; D008025:Ligases; D010453:Peptide Synthases