Rhythmic binding of a WHITE COLLAR-containing complex to the frequency promoter is inhibited by FREQUENCY.
The biological clock of Neurospora crassa includes interconnected transcriptional and translational feedback loops that cause both the transcript and protein encoded by the frequency gene (frq) to undergo the robust daily oscillations in abundance, which are essential for clock function. To understand better the mechanism generating rhythmic frq transcript, reporter constructs were used to show that the oscillation in frq message is transcriptionally regulated, and a single cis-acting element in the frq promoter, the Clock Box (C box), is both necessary and sufficient for this rhythmic transcription. Nuclear protein extracts used in binding assays revealed that a White Collar (WC)-1- and WC-2-containing complex (WCC) binds to the C box in a time-of-day-specific manner. Overexpression of an ectopic copy of FRQ or addition of in vitro-generated FRQ resulted in reduced WCC binding to the C box. These data suggest that oscillations in frq transcript result from WCC binding to the frq promoter and activating transcription with subsequent changes in FRQ levels having an inverse effect on WCC binding. In this way rhythmic expression and turnover of FRQ drives the rhythm in its own transcription.
Froehlich
Allan C
AC
Department of Genetics, Dartmouth Medical School, HB7400, Hanover, NH 03755, USA.
Loros
Jennifer J
JJ
Dunlap
Jay C
JC
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics; D001483:Base Sequence; D001665:Binding Sites; D002940:Circadian Rhythm; D017931:DNA Primers; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism; D007700:Kinetics; D008969:Molecular Sequence Data; D009492:Neurospora crassa / Q000235:genetics* / Q000502:physiology; D010957:Plasmids; D011401:Promoter Regions, Genetic; D015183:Restriction Mapping; D014157:Transcription Factors / Q000037:antagonists & inhibitors / Q000235:genetics* / Q000378:metabolism; D016335:Zinc Fingers
D001426:Bacterial Proteins; D017931:DNA Primers; D004268:DNA-Binding Proteins; C087405:FRQ protein, Neurospora crassa; D005656:Fungal Proteins; D014157:Transcription Factors; C105589:wc-1 protein, Neurospora crassa