title: The function of the clock-associated transcriptional regulator CCA1 (CIRCADIAN CLOCK-ASSOCIATED 1) in Arabidopsis thaliana.
abstract: In the model higher plant Arabidopsis thaliana, the CCA1 (CIRCADIAN CLOCK-ASSOCIATED 1) gene plays important circadian clock-associated roles. The CCA1 protein is a member of a small subfamily of single MYB-related transcription factors. This family consists of several homologous CCA1-like transcription factors, including the closest homolog LHY (LATE ELONGATED HYPOCOTYL). To gain insight into the molecular function of CCA1 and its homologs, here we took a unique genetic approach that was recently developed for Arabidopsis thaliana. Through this strategy, referred to as CRES-T (Chimeric REpressor Silencing Technology), a transgenic plant was constructed to produce a dominant negative transcriptional repressor (designated CCA1-SRDX). By employing the resulting transgenic lines, together with previously established cca1 lhy double mutant and CCA1-ox (over-expressing) plants, their circadian clock-associated phenotypes were examined and compared with each other. The observed clock-associated phenotypes of the CCA1-SRDX plants were very similar to those of CCA1-ox, but not to those of cca1 lhy, suggesting that CCA1 acts predominantly as a transcriptional repressor in nature. However, the developmental morphology (or architecture) of adult CCA1-SRDX plants were quite different from that of CCA1-ox, suggesting that CCA1 might also be implicated, directly or indirectly, in an as yet unknown circadian-associated output pathway at a late developmental stage.
authors.affiliation: Laboratory of Molecular Microbiology, School of Agriculture, Nagoya University, Chikusa-ku, Nagoya 464-8601, Japan.
authors.forename: Masakazu
authors.initials: M
authors.lastname: Kawamura
authors.forename: Shogo
authors.initials: S
authors.lastname: Ito
authors.forename: Norihito
authors.initials: N
authors.lastname: Nakamichi
authors.forename: Takafumi
authors.initials: T
authors.lastname: Yamashino
authors.forename: Takeshi
authors.initials: T
authors.lastname: Mizuno
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002940:Circadian Rhythm / Q000235:genetics; D003116:Color; D035264:Flowers / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D008027:Light; D010455:Peptides / Q000378:metabolism; D010641:Phenotype; D017440:Photoperiod; D010802:Phylogeny; D030821:Plants, Genetically Modified; D012680:Sensitivity and Specificity; D012689:Sequence Homology, Nucleic Acid; D013997:Time Factors; D014157:Transcription Factors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; C114425:CCA1 protein, Arabidopsis; D010455:Peptides; D014157:Transcription Factors