Sugar Time

Metabolic activity, not light, drives the circadian clock in cyanobacteria.

Catherine Offord
Mar 1, 2016

SWEET TIMEKEEPERS: S. elongatus cyanobacteria (chlorophyll visible here) set their circadian clocks by metabolism rather than light.YI LIAO, UNIVERSITY OF CHICAGO


The paper
G.K. Pattanayak et al., “Controlling the cyanobacterial clock by synthetically rewiring metabolism,” Cell Reports, 13:2362-67, 2015.

Tiny tickers
Like many organisms, the photosynthetic cyanobacterium Synechococcus elongatus has a circadian clock that cycles with light/dark rhythms. The timekeeper has just three core proteins—KaiA, KaiB, and KaiC—making it the simplest circadian clock known to science. Given that researchers have failed to identify light-sensitive clock components in S. elongatus, but have demonstrated that Kai proteins respond to metabolic activity, some scientists suggest that cyanobacteria are synchronizing to the downstream metabolites of photosynthesis, as opposed to light itself.

Decoupling metabolism
To tease apart light-dark cycles and metabolism, researchers led by Michael Rust at the University of Chicago engineered a strain of...