The circadian clock and darkness control natural competence in cyanobacteria

Taton, A., Erikson, C., Yang, Y. et al. The circadian clock and darkness control natural competence in cyanobacteria. Nat Commun 11, 1688 (2020).


The cyanobacterium Synechococcus elongatus is a model organism for the study of circadian rhythms. It is naturally competent for transformation—that is, it takes up DNA from the environment, but the underlying mechanisms are unclear. Here, we use a genome-wide screen to identify genes required for natural transformation in S. elongatus, including genes encoding a conserved Type IV pilus, genes known to be associated with competence in other bacteria, and others. Pilus biogenesis occurs daily in the morning, while natural transformation is maximal when the onset of darkness coincides with the dusk circadian peak. Thus, the competence state in cyanobacteria is regulated by the circadian clock and can adapt to seasonal changes of day length.

Further reading

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Timing is everything. A fresh example supporting the old saying has been found in connection with the systems regulated by biological clocks.

Research on circadian rhythms, our internal 24-hour patterns that affect sleep-wake and metabolic cycles, has shown that timing is key for human health. When our activities and internal circadian clocks are out of step with the natural day-night cycle—for example, in cases of irregular shift work, jet lag and poor sleep-wake habits—we increase our risk of disease because of the mistiming of important biological processes. But the genetics behind these mechanisms haven’t been well established. Read more at  

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