The Inner Workings of a Clock

Science Signaling  07 Aug 2012:
Vol. 5, Issue 236, pp. ec209
DOI: 10.1126/scisignal.2003467

Eukaryotic circadian clocks are built at least in part on transcriptional feedback loops, but the mechanisms underlying circadian feedback are poorly understood. Padmanabhan et al. explored the transcriptional feedback mechanism at the heart of the mammalian circadian clock. The proteins PERIOD (PER) and CRYPTOCHROME suppress transcription of their own genes. PER complexes do so in part by recruiting a histone deacetylase to promoters of clock genes. But PER is also present on DNA in a complex with Senataxin, a helicase that functions in transcriptional termination. Senataxin appears to be inhibited in the PER complex, thus inhibiting termination and further reducing the rate of transcription.

K. Padmanabhan, M. S. Robles, T. Westerling, C. J. Weitz, Feedback regulation of transcriptional termination by the mammalian circadian clock PERIOD complex. Science 337, 599–602 (2012). [Abstract] [Full Text]