Transcriptional regulation of the Neurospora circadian clock gene wc-1 affects the phase of circadian output

WHITE COLLAR-1 (WC-1) is the limiting component of the White Collar Complex (WCC) controlling expression of the Neurospora circadian clock protein Frequency (FRQ). Accumulation of WC-1 is supported by FRQ on a post-transcriptional level. Here, we show that transcription of wc-1 is organized in a complex way. Three promoters drive transcription of wc-1. Pdist is dependent on WCC. Pprox is independent of WCC in darkness, but inducible by light in a WCC-dependent manner. A third promoter, Pint, is located in the wc-1 open reading frame and promotes expression of an amino-terminally truncated WC-1 isoform of unknown function. Expression of wc-1 by Pdist or Pprox alone, or by a heterologous promoter, affects the entrained phase of circadian conidiation and the response of Neurospora to light. Our results indicate that transcriptional regulation of wc-1 is required to modulate the circadian phase of clock output.