Circadian Rhythms

Flies and jetlag

Science's STKE  27 Jun 2006:
Vol. 2006, Issue 341, pp. tw217
DOI: 10.1126/stke.3412006tw217

Circadian clocks can be reset to a new phase by a brief exposure to light, but the molecular details of this resetting are not clear. In Drosophila, a light-sensitive protein cryptochrome undergoes a conformational change in response to light and binds to a clock component, the protein TIMELESS (TIM). This interaction then triggers TIM degradation, effectively resetting the clock. By screening mutant flies that show reduced sensitivity to this light-induced resetting, Koh et al. identify a gene, termed jetlag, that is necessary for degradation of TIM after the light pulse. JETLAG exists in a complex with TIM and increases its ubiquitination, a tag that marks the protein for degradation. Thus, JETLAG is an F-box protein that targets TIM for ubiquitination and consequent rapid degradation in response to light.

K. Koh, X. Zheng, A. Sehgal, JETLAG resets the Drosophila circadian clock by promoting light-induced degradation of TIMELESS. Science 312, 1809-1812 (2006). [Abstract] [Full Text]