Clock-associated genes in Arabidopsis: a family affair.
The identification of components of the plant circadian clock has been advanced recently with the success of two forward genetics approaches. The ZEITLUPE and TOC1 loci were cloned and each was found to be part of two separate, larger gene families with intriguing domain structures. The ZTL family of proteins contains a subclass of the PAS domain coupled to an F box and kelch motifs, suggesting that they play a role in a novel light-regulated ubiquitination mechanism. TOC1 shares similarity to the receiver domain of the well-known two-component phosphorelay signalling systems, combined with a strong similarity to a region of the CONSTANS transcription factor, which is involved in controlling flowering time. When added to the repertoire of previously identified clock-associated genes, it is clear that both similarities and differences with other circadian systems will emerge in the coming years.
Somers
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Department of Plant Biology, Ohio State University, Columbus, OH 43210, USA. somers.24@osu.edu
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000502:physiology*; D029681:Arabidopsis Proteins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism*; D002940:Circadian Rhythm / Q000235:genetics*; D018506:Gene Expression Regulation, Plant; D008969:Molecular Sequence Data; D005810:Multigene Family; D010940:Plant Proteins / Q000235:genetics; D017434:Protein Structure, Tertiary; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors
C091601:ABI3 protein, Arabidopsis; C448162:APRR3 protein, Arabidopsis; C448160:APRR5 protein, Arabidopsis; C448161:APRR7 protein, Arabidopsis; C448159:APRR9 protein, Arabidopsis; D029681:Arabidopsis Proteins; D010940:Plant Proteins; C411822:TOC1 protein, Arabidopsis; D014157:Transcription Factors; C410503:ZTL protein, Arabidopsis