Hourglass Model for a Protein-Based Circadian Oscillator

Eldon Emberly and Ned S. Wingreen
Phys. Rev. Lett. 96, 038303 – Published 24 January 2006

Abstract

Many organisms possess internal biochemical clocks, known as circadian oscillators, which allow them to regulate their biological activity with a 24-hour period. It was recently discovered that the circadian oscillator of photosynthetic cyanobacteria is able to function in a test tube with only three proteins, KaiA, KaiB, and KaiC, and ATP. Biochemical events are intrinsically stochastic, and this tends to desynchronize oscillating protein populations. We propose that stability of the Kai-protein oscillator relies on active synchronization by (i) monomer exchange between KaiC hexamers during the day, and (ii) formation of clusters of KaiC hexamers at night. Our results highlight the importance of collective assembly or disassembly of proteins in biochemical networks, and may help guide design of novel protein-based oscillators.

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  • Received 15 September 2005

DOI:https://doi.org/10.1103/PhysRevLett.96.038303

©2006 American Physical Society

Authors & Affiliations

Eldon Emberly

  • Physics Department, Simon Fraser University, Burnaby, British Columbia, Canada V5A 1S6

Ned S. Wingreen

  • Department of Molecular Biology, Princeton University, Princeton, New Jersey 08544-1014, USA

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Vol. 96, Iss. 3 — 27 January 2006

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