title: Phosphorylation-dependent maturation of Neurospora circadian clock protein from a nuclear repressor toward a cytoplasmic activator.
abstract: Frequency (FRQ) is a central component of interconnected negative and positive limbs of feedback loops of the circadian clock of Neurospora. In the negative limb, FRQ inhibits its transcriptional activator White Collar Complex (WCC) and in the positive limb, FRQ supports accumulation of WCC. We show that these conflicting functions are confined to distinct subcellular compartments and coordinated in temporal fashion. Inactivation of the transcriptional activator WCC requires nuclear FRQ and occurs early after the onset of FRQ expression. Support of WCC accumulation requires cytosolic FRQ and occurs on a post-translational level, when high amounts of FRQ have accumulated. The transcriptional function of FRQ in the negative loop and its post-translational function in the positive loop are independent and associated with distinct regions of FRQ. Phosphorylation of FRQ at the PEST-2 region triggers its maturation from a nuclear repressor toward a cytoplasmic activator.
authors.affiliation: Biochemie-Zentrum der Universität Heidelberg, 69120 Heidelberg, Germany.
authors.forename: Tobias
authors.initials: T
authors.lastname: Schafmeier
authors.forename: Krisztina
authors.initials: K
authors.lastname: Káldi
authors.forename: Axel
authors.initials: A
authors.lastname: Diernfellner
authors.forename: Christian
authors.initials: C
authors.lastname: Mohr
authors.forename: Michael
authors.initials: M
authors.lastname: Brunner
mesh_terms: D000818:Animals; D056926:CLOCK Proteins; D002467:Cell Nucleus / Q000235:genetics / Q000378:metabolism; D002940:Circadian Rhythm / Q000235:genetics / Q000502:physiology; D003600:Cytosol / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D029721:Drosophila Proteins / Q000235:genetics / Q000378:metabolism; D025461:Feedback, Physiological; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D015966:Gene Expression Regulation, Fungal / Q000502:physiology*; D008954:Models, Biological; D009491:Neurospora / Q000235:genetics / Q000502:physiology*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D014170:Transformation, Genetic
chemical_list: D004268:DNA-Binding Proteins; D029721:Drosophila Proteins; C087405:FRQ protein, Neurospora crassa; D005656:Fungal Proteins; D009687:Nuclear Proteins; D015534:Trans-Activators; D014157:Transcription Factors; C096445:tim protein, Drosophila; C105589:wc-1 protein, Neurospora crassa; D056926:CLOCK Proteins