Cip4, a new COP1 target, is a nucleus-localized positive regulator of Arabidopsis photomorphogenesis.
Arabidopsis COP1 acts within the nucleus to repress photomorphogenesis, and its nuclear abundance is negatively regulated by light. Here, we report the identification of a COP1-interactive partner, CIP4. CIP4 is a nuclear protein and a potent transcription coactivator. Conditional suppression of CIP4 expression resulted in an elongated hypocotyl and reduced chlorophyll content in the light, indicating that CIP4 is required for the promotion of photomorphogenesis. Furthermore, CIP4 was revealed to act downstream of multiple photoreceptors as well as COP1 in mediating light control of development. CIP4 expression is light inducible and regulated by COP1. However, CIP4 does not play a role in mediating the light induction of anthocyanin accumulation. Together with our previous studies of CIP7 and HY5, our data suggest that COP1 interacts directly with and regulates multiple physiological targets, which in turn regulate distinct sets of light-regulated responses.
Yamamoto
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Plant Function Exploration Team, Plant Functional Genomics Research Group, Genomic Sciences Center, RIKEN, Hirosawa 2-1, Wako, Saitama 351-0198, Japan.
Deng
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Matsui
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D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites; D002467:Cell Nucleus / Q000378:metabolism; D017343:Genes, Plant; D008027:Light; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D020319:Oligodeoxyribonucleotides, Antisense / Q000235:genetics; D010641:Phenotype; D045322:Photosynthetic Reaction Center Complex Proteins / Q000378:metabolism; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D015533:Transcriptional Activation; D044767:Ubiquitin-Protein Ligases
D029681:Arabidopsis Proteins; D009687:Nuclear Proteins; D020319:Oligodeoxyribonucleotides, Antisense; D045322:Photosynthetic Reaction Center Complex Proteins; C471983:AT2G32950 protein, Arabidopsis; D044767:Ubiquitin-Protein Ligases