Circadian Rhythms

Many Ways to Make a Circadian Oscillator

Science's STKE  08 Jun 2004:
Vol. 2004, Issue 236, pp. tw208
DOI: 10.1126/stke.2362004tw208

Circadian pacemakers keep cyanobacteria and eukaryotes on a 24-hour cycle that is synchronized with the environment. In Drosophila, a cryptochrome (CRY) is the primary circadian photoreceptor. It interacts with the transcription factors PERIOD (PER) and TIMELESS (TIM) that are involved in regulation of clock genes. However, the molecular mechanism of entrainment has been unclear. Busza et al. show that CRY binding to TIM is light-dependent in flies. The interaction is transient, but it commits TIM to proteosomal degradation. In CRY, the photolyase homology domain is involved in light detection and phototransduction, whereas the C-terminal domain regulates CRY stability and the CRY-TIM interaction. These results contrast with the functions of Arabidopsis CRY domains.

A. Busza, M. Emery-Le, M. Rosbash, P. Emery, Roles of the two Drosophila CRYPTOCHROME structural domains in circadian photoreception. Science 304, 1503-1506 (2004). [Abstract] [Full Text]