Optimal Discretization in Hour-Glass Molecular Clocks Driven by Oscillating Free Energy

Fuente: arXiv
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Main Authors: Zhen, Zhuangcheng, Shi, Kaiyue, Ouyang, Qi, Cao, Yuansheng
Format: Preprint
Published: 2026
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author Zhen, Zhuangcheng
Shi, Kaiyue
Ouyang, Qi
Cao, Yuansheng
author_facet Zhen, Zhuangcheng
Shi, Kaiyue
Ouyang, Qi
Cao, Yuansheng
contents Hour-glass clocks do not free-run; they keep time by riding an external rhythm. Motivated by the primordial KaiBC system in cyanobacteria, we study a driven, finite-state molecular clock that advances through a small number of biochemical states under an intrinsic driving energy and a rotating energy landscape set by day-night metabolism. In the continuum limit, coherence is maximized at a resonant operating point where the intrinsic drift matches the driving frequency. In realistic clocks with a finite number of states, discreteness matters: as the rotating landscape sweeps over a lattice of states, it generates a small and high frequency vibration of the collective phase that makes timing inaccurate. Combining the resonant cost with this discreteness penalty yields a trade-off in the number of states: few states are energetically cheap but noisy; many states are precise but costly. The optimum lies at moderate discretization (typically five to fifteen states) and an environmental coupling that is strong enough for responsiveness yet weak enough to avoid large discrete-state vibrations. These design rules rationalize why KaiC's hexameric architecture falls near the predicted optimum and suggest a general principle for hour-glass clocks across organisms.
format Preprint
id arxiv_https___arxiv_org_abs_2601_08395
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Optimal Discretization in Hour-Glass Molecular Clocks Driven by Oscillating Free Energy
Zhen, Zhuangcheng
Shi, Kaiyue
Ouyang, Qi
Cao, Yuansheng
Biological Physics
Statistical Mechanics
Hour-glass clocks do not free-run; they keep time by riding an external rhythm. Motivated by the primordial KaiBC system in cyanobacteria, we study a driven, finite-state molecular clock that advances through a small number of biochemical states under an intrinsic driving energy and a rotating energy landscape set by day-night metabolism. In the continuum limit, coherence is maximized at a resonant operating point where the intrinsic drift matches the driving frequency. In realistic clocks with a finite number of states, discreteness matters: as the rotating landscape sweeps over a lattice of states, it generates a small and high frequency vibration of the collective phase that makes timing inaccurate. Combining the resonant cost with this discreteness penalty yields a trade-off in the number of states: few states are energetically cheap but noisy; many states are precise but costly. The optimum lies at moderate discretization (typically five to fifteen states) and an environmental coupling that is strong enough for responsiveness yet weak enough to avoid large discrete-state vibrations. These design rules rationalize why KaiC's hexameric architecture falls near the predicted optimum and suggest a general principle for hour-glass clocks across organisms.
title Optimal Discretization in Hour-Glass Molecular Clocks Driven by Oscillating Free Energy
topic Biological Physics
Statistical Mechanics
url https://arxiv.org/abs/2601.08395