Thermally regulated translational control of FRQ mediates aspects of temperature responses in the neurospora circadian clock

Cell. 1997 May 2;89(3):477-86. doi: 10.1016/s0092-8674(00)80228-7.


Two forms of FRQ, a central component of the Neurospora circadian clock, arise through alternative in-frame initiation of translation. Either form alone suffices for a functional clock at some temperatures, but both are always necessary for robust rhythmicity. Temperature regulates the ratio of FRQ forms by favoring different initiation codons at different temperatures; when either initiation codon is eliminated, the temperature range permissive for rhythmicity is demonstrably reduced. This temperature-influenced choice of translation-initiation site represents a novel adaptive mechanism that extends the physiological temperature range over which clocks function. Additionally, a temperature-dependent threshold level of FRQ is required to establish the feedback loop comprising the oscillator. These data may explain how temperature limits permissive for rhythmicity are established, thus providing a molecular understanding for a basic characteristic of circadian clocks.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Biological Clocks / genetics
  • Circadian Rhythm / genetics*
  • Codon, Initiator / genetics
  • Fungal Proteins / chemistry
  • Fungal Proteins / genetics*
  • Gene Expression Regulation, Fungal / physiology
  • Isomerism
  • Mutagenesis, Site-Directed / physiology
  • Neurospora / chemistry
  • Neurospora / genetics*
  • Protein Biosynthesis / physiology*
  • Temperature


  • Codon, Initiator
  • FRQ protein, Neurospora crassa
  • Fungal Proteins