The PAS/LOV protein VIVID supports a rapidly dampened daytime oscillator that facilitates entrainment of the Neurospora circadian clock.
A light-entrainable circadian clock controls development and physiology in Neurospora crassa. Existing simple models for resetting based on light pulses (so-called nonparametric entrainment) predict that constant light should quickly send the clock to an arrhythmic state; however, such a clock would be of little use to an organism in changing photoperiods in the wild, and we confirm that true, albeit dampened, rhythmicity can be observed in extended light. This rhythmicity requires the PAS/LOV protein VIVID (VVD) that acts, in the light, to facilitate expression of an oscillator that is related to, but distinguishable from, the classic FREQUENCY/WHITE-COLLAR complex (FRQ/WCC)-based oscillator that runs in darkness. VVD prevents light resetting of the clock at dawn but, by influencing frq RNA turnover, promotes resetting at dusk, thereby allowing the clock to run through the dawn transition and take its phase cues from dusk. Consistent with this, loss of VVD yields a clock whose performance follows the simple predictions of earlier models, and overexpression of VVD restores rhythmicity in the light and sensitivity of phase to the duration of the photoperiod.
Elvin
Mark
M
Faculty of Life Sciences, The University of Manchester, Manchester, M13 9PT, United Kingdom.
Loros
Jennifer J
JJ
Dunlap
Jay C
JC
Heintzen
Christian
C
D002940:Circadian Rhythm / Q000502:physiology*; D003624:Darkness; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal / Q000502:physiology*; D009492:Neurospora crassa / Q000502:physiology*; D017440:Photoperiod; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism
C087405:FRQ protein, Neurospora crassa; D005656:Fungal Proteins; D014157:Transcription Factors; C423283:VVD protein, Neurospora crassa