Editors' ChoiceCircadian clocks

Synchronize Your Watches

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Science Signaling  18 Jan 2011:
Vol. 4, Issue 156, pp. ec18
DOI: 10.1126/scisignal.4156ec18

Biological clocks have periods of about 24 hours but rely on entrainment from exposure to light to stay in synch with day length. Rust et al. show that, in cyanobacteria, such entrainment is coupled, at least in part, by the effect of light on photosynthesis increasing the relative concentration of adenosine triphosphate (ATP) to adenosine diphosphate. The cyanobacterial clock can be reconstituted in vitro from just three proteins that are regulated through phosphorylation reactions in which ATP is a substrate. One of the proteins, KaiC, can integrate the status of the endogenous clock through its interaction with the KaiA component, and with the metabolic state of the cell, through competitive inhibition of KaiC’s binding to its substrate ATP. A mathematical model was developed that could reproduce the entrainment of the clock by light.

M. J. Rust, S. S. Golden, E. K. O’Shea, Light-driven changes in energy metabolism directly entrain the cyanobacterial circadian oscillator. Science 331, 220–223 (2011). [Abstract] [Full Text]

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