Neurospora WC-1 recruits SWI/SNF to remodel frequency and initiate a circadian cycle

PLoS Genet. 2014 Sep 25;10(9):e1004599. doi: 10.1371/journal.pgen.1004599. eCollection 2014 Sep.


In the negative feedback loop comprising the Neurospora circadian oscillator, the White Collar Complex (WCC) formed from White Collar-1 (WC-1) and White Collar-2 (WC-2) drives transcription of the circadian pacemaker gene frequency (frq). Although FRQ-dependent repression of WCC has been extensively studied, the mechanism by which the WCC initiates a circadian cycle remains elusive. Structure/function analysis of WC-1 eliminated domains previously thought to transactivate frq expression but instead identified amino acids 100-200 as essential for frq circadian expression. A proteomics-based search for coactivators with WCC uncovered the SWI/SNF (SWItch/Sucrose NonFermentable) complex: SWI/SNF interacts with WCC in vivo and in vitro, binds to the Clock box in the frq promoter, and is required both for circadian remodeling of nucleosomes at frq and for rhythmic frq expression; interestingly, SWI/SNF is not required for light-induced frq expression. These data suggest a model in which WC-1 recruits SWI/SNF to remodel and loop chromatin at frq, thereby activating frq expression to initiate the circadian cycle.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Circadian Rhythm*
  • DNA-Binding Proteins / chemistry
  • DNA-Binding Proteins / metabolism*
  • Fungal Proteins / chemistry
  • Fungal Proteins / genetics
  • Fungal Proteins / metabolism*
  • Gene Expression Regulation, Fungal
  • Gene Knockout Techniques
  • Models, Biological
  • Mutation
  • Neurospora / physiology*
  • Nucleosomes / metabolism
  • Promoter Regions, Genetic
  • Protein Binding
  • Protein Interaction Domains and Motifs
  • Transcription Factors / chemistry
  • Transcription Factors / metabolism*
  • Transcription, Genetic


  • DNA-Binding Proteins
  • Fungal Proteins
  • Nucleosomes
  • Transcription Factors
  • wc-1 protein, Neurospora crassa