A DOUBLETIME kinase binding domain on the Drosophila PERIOD protein is essential for its hyperphosphorylation, transcriptional repression, and circadian clock function.
A common feature of animal circadian clocks is the progressive phosphorylation of PERIOD (PER) proteins from hypo- to hyperphosphorylated species, events that are highly dependent on casein kinase 1 epsilon (termed DOUBLETIME [DBT] in Drosophila melanogaster) and necessary for normal clock progression. Drosophila PER (dPER) functions in the negative limb of the clockworks by presumably binding to the transcription factor CLOCK (CLK) and inhibiting its transactivation activity. Here, we identify a small region on dPER that is conserved with mammalian PERs and contains the major in vivo DBT binding domain, termed dPDBD (for dPER DBT binding domain). This domain is required for the manifestation of molecular and behavioral rhythms in vivo. In the absence of the dPDBD, the dPER protein is present at constant high levels throughout a daily cycle, undergoes little phosphorylation, and is severely impaired in its ability to function as a transcriptional repressor. Our findings indicate that the binding of dPER to CLK is not sufficient for transcriptional inhibition, implicating a more indirect mode of action whereby dPER acts as a molecular bridge to "deliver" DBT and/or other factors that directly repress CLK-dependent gene expression.
Kim
Eun Young
EY
Rutgers University, Center for Advanced Biotechnology and Medicine, Piscataway, NJ 08854, USA.
Ko
Hyuk Wan
HW
Yu
Wangjie
W
Hardin
Paul E
PE
Edery
Isaac
I
D000595:Amino Acid Sequence; D000818:Animals; D001683:Biological Clocks; D048149:Casein Kinase 1 epsilon / Q000378:metabolism*; D018797:Cell Cycle Proteins / Q000378:metabolism; D002940:Circadian Rhythm; D029721:Drosophila Proteins / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000235:genetics* / Q000502:physiology; D025461:Feedback, Physiological; D008954:Models, Biological; D008969:Molecular Sequence Data; D009043:Motor Activity; D050505:Mutant Proteins / Q000378:metabolism; D009687:Nuclear Proteins / Q000737:chemistry* / Q000378:metabolism*; D056950:Period Circadian Proteins; D010766:Phosphorylation; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D017434:Protein Structure, Tertiary; D012097:Repressor Proteins / Q000378:metabolism; D017384:Sequence Deletion; D013329:Structure-Activity Relationship; D014158:Transcription, Genetic; D015533:Transcriptional Activation / Q000235:genetics; D044767:Ubiquitin-Protein Ligases / Q000378:metabolism
D018797:Cell Cycle Proteins; D029721:Drosophila Proteins; D050505:Mutant Proteins; D009687:Nuclear Proteins; C539040:PER protein, Drosophila; D056950:Period Circadian Proteins; D012097:Repressor Proteins; C113519:dco protein, Drosophila; C110233:slmb protein, Drosophila; C096445:tim protein, Drosophila; D044767:Ubiquitin-Protein Ligases; D048149:Casein Kinase 1 epsilon