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Title: Does the cyanobacterial KaiABC clock run near minimal cost?
Plain: Three proteins called KaiA, KaiB and KaiC keep a 24-hour rhythm in a test tube by burning ATP. The question is whether they spend close to the least energy that physics allows for their precision.
Precise: For the reconstituted KaiABC oscillator (period $\sim 24\,\mathrm{h}$; ATP use of approximately 15 ATP per KaiC monomer per day), measure the phase-diffusion constant and the total entropy production per period, and compare with the thermodynamic uncertainty relation $\operatorname{Var}(N_T)/\langle N_T\rangle^2 \ge 2 k_B/\Sigma_T$ for the cycle count $N_T$ over time T with entropy production $\Sigma_T$. Answer: the ratio of measured cost to the bound.
Settled by: Simultaneous measurement of phase diffusion and ATP hydrolysis rate in the reconstituted oscillator at fixed protein concentrations.
Kind: well-posed
Answer type: value
References: (empty)
Literature status: open
Status note: A 2015 model (Cao, Wang, Ouyang, Tu) linked KaiABC precision to its free-energy consumption; a direct test against a rigorous bound is not established.
Posed since: (empty)