Circadian rhythms of superhelical status of DNA in cyanobacteria
- 20 November 2007
- journal article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences of the United States of America
- Vol. 104 (47), 18819-18824
- https://doi.org/10.1073/pnas.0706069104
Abstract
The cyanobacterium Synechococcus elongatus expresses robust circadian (daily) rhythms under the control of the KaiABC-based core clockwork. Unlike eukaryotic circadian systems characterized thus far, the cyanobacterial clockwork modulates gene expression patterns globally and specific clock gene promoters are not necessary in mediating the circadian feedback loop. The oscilloid model postulates that global rhythms of transcription are based on rhythmic changes in the status of the cyanobacterial chromosome that are ultimately controlled by the KaiABC oscillator. By using a nonessential, cryptic plasmid (pANS) as a reporter of the superhelical state of DNA in cyanobacteria, we show that the supercoiling status of this plasmid changes in a circadian manner in vivo. The rhythm of topological change in the plasmid is conditional; this change is rhythmic in constant light and in light/dark cycles, but not in constant darkness. In further support of the oscilloid model, cyanobacterial promoters that are removed from their native chromosomal locations and placed on a plasmid preserve their circadian expression patterns.This publication has 48 references indexed in Scilit:
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