dorsal/arxiv
View SchemaAn allosteric model of KaiC phosphorylation
| Authors | Jeroen S. van Zon, David K. Lubensky, Pim R. H. Altena, Pieter Rein ten Wolde |
|---|---|
| Categories | |
| ArXiv ID | q-bio/0703009 |
| URL | https://arxiv.org/abs/q-bio/0703009 |
| DOI | 10.1073/pnas.0608665104 |
Abstract
In a recent series of ground-breaking experiments, Nakajima et al. [Science 308, 414-415 (2005)] showed that the three cyanobacterial clock proteins KaiA, KaiB, and KaiC are sufficient in vitro to generate circadian phosphorylation of KaiC. Here, we present a mathematical model of the Kai system. At its heart is the assumption that KaiC can exist in two conformational states, one favoring phosphorylation and the other dephosphorylation. Each individual KaiC hexamer then has a propensity to be phosphorylated in a cyclic manner. To generate macroscopic oscillations, however, the phosphorylation cycles of the different hexamers must be synchronized. We propose a novel synchronisation mechanism based on differential affinity: KaiA stimulates KaiC phosphorylation, but the limited supply of KaiA dimers binds preferentially to those KaiC hexamers that are falling behind in the oscillation. KaiB sequesters KaiA and stabilizes the dephosphorylating KaiC state. We show that our model can reproduce a wide range of published data, including the observed insensitivity of the oscillation period to variations in temperature, and that it makes nontrivial predictions about the effects of varying the concentrations of the Kai proteins.
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"abstract": "In a recent series of ground-breaking experiments, Nakajima et al. [Science\n308, 414-415 (2005)] showed that the three cyanobacterial clock proteins KaiA,\nKaiB, and KaiC are sufficient in vitro to generate circadian phosphorylation of\nKaiC. Here, we present a mathematical model of the Kai system. At its heart is\nthe assumption that KaiC can exist in two conformational states, one favoring\nphosphorylation and the other dephosphorylation. Each individual KaiC hexamer\nthen has a propensity to be phosphorylated in a cyclic manner. To generate\nmacroscopic oscillations, however, the phosphorylation cycles of the different\nhexamers must be synchronized. We propose a novel synchronisation mechanism\nbased on differential affinity: KaiA stimulates KaiC phosphorylation, but the\nlimited supply of KaiA dimers binds preferentially to those KaiC hexamers that\nare falling behind in the oscillation. KaiB sequesters KaiA and stabilizes the\ndephosphorylating KaiC state. We show that our model can reproduce a wide range\nof published data, including the observed insensitivity of the oscillation\nperiod to variations in temperature, and that it makes nontrivial predictions\nabout the effects of varying the concentrations of the Kai proteins.",
"arxiv_id": "q-bio/0703009",
"authors": [
"Jeroen S. van Zon",
"David K. Lubensky",
"Pim R. H. Altena",
"Pieter Rein ten Wolde"
],
"categories": [
"q-bio.MN",
"q-bio.CB"
],
"doi": "10.1073/pnas.0608665104",
"title": "An allosteric model of KaiC phosphorylation",
"url": "https://arxiv.org/abs/q-bio/0703009"
},
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