Editors' ChoiceCircadian Rhythms

Defining necessary circadian clock elements

Sci. Signal.  03 Feb 2015:
Vol. 8, Issue 362, pp. ec27
DOI: 10.1126/scisignal.aaa8158

The circadian clock in organisms as diverse as fungi and humans has a rather similar structure: Timing depends on daily cycles of transcription in circuits in which feedback loops control the timing of oscillations. A critical role has been ascribed to negative elements, which lead to inhibition of their own transcription, and to degradation of these elements, which is signaled by phosphorylation events. However, Larrondo et al. show that in the fungus Neurospora, after manipulations that prevent phosphorylation-signaled degradation of the negative element FREQUENCY (FRQ), rhythms still persist (see the Perspective by Kramer). They suggest a model in which other phosphorylation events on Frq (of which there are over 100) must have critical roles in controlling the clock, independent of negative element degradation.

L. F. Larrondo, C. Olivares-Yañez, C. L. Baker, J. J. Loros, J. C. Dunlap, Decoupling circadian clock protein turnover from circadian period determination. Science 347, 1257277 (2015). [Abstract] [Full Text]

A. Kramer, When the circadian clock becomes blind. Science 347, 476–477 (2015). [Summary] [Full Text]