Revision 1

Accepted · first revision · record

Title: Mechanism of temperature compensation in circadian clocks
Plain: Most chemical reactions speed up strongly when warmed, yet circadian clocks, the cell's 24-hour timers, keep nearly the same period over a wide range of temperatures. How the clock cancels the temperature dependence of its reactions is not understood.
Precise: For the KaiABC oscillator in vitro, the period has $Q_{10}$ of approximately 1.1 between about 298 and 308 K while individual rate constants have $Q_{10} \sim 2$ to 3 ($Q_{10}$ = rate ratio for a 10 K rise). Identify the mechanism (balanced activation energies of opposing reactions, temperature-insensitive KaiC ATPase, structural constraint) that makes $d \ln(\mathrm{period})/dT$ small, and predict the period's temperature dependence from measured rate constants.
Settled by: A kinetic model built from independently measured temperature-dependent rate constants that predicts the period versus temperature and the effect of mutations that break compensation.
Kind: phenomenon
Answer type: mechanism
References: (empty)
Literature status: open
Status note: (empty)
Posed since: 1954