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A saturated reaction in repressor synthesis creates a daytime dead zone in circadian clocks
Negative feedback loops (NFLs) for circadian clocks include light-responsive reactions that allow the clocks to shift their phase depending on the timing of light signals. Phase response curves (PRCs) for light signals in various organisms include a time interval called a dead zone where light signa...
Autores principales: | , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Public Library of Science
2019
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6396941/ https://www.ncbi.nlm.nih.gov/pubmed/30779745 http://dx.doi.org/10.1371/journal.pcbi.1006787 |
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author | Uriu, Koichiro Tei, Hajime |
author_facet | Uriu, Koichiro Tei, Hajime |
author_sort | Uriu, Koichiro |
collection | PubMed |
description | Negative feedback loops (NFLs) for circadian clocks include light-responsive reactions that allow the clocks to shift their phase depending on the timing of light signals. Phase response curves (PRCs) for light signals in various organisms include a time interval called a dead zone where light signals cause no phase shift during daytime. Although the importance of the dead zone for robust light entrainment is known, how the dead zone arises from the biochemical reactions in an NFL underlying circadian gene expression rhythms remains unclear. In addition, the observation that the light-responsive reactions in the NFL vary between organisms raises the question as to whether the mechanism for dead zone formation is common or distinct between different organisms. Here we reveal by mathematical modeling that the saturation of a biochemical reaction in repressor synthesis in an NFL is a common mechanism of daytime dead zone generation. If light signals increase the degradation of a repressor protein, as in Drosophila, the saturation of repressor mRNA transcription nullifies the effect of light signals, generating a dead zone. In contrast, if light signals induce the transcription of repressor mRNA, as in mammals, the saturation of repressor translation can generate a dead zone by cancelling the influence of excess amount of mRNA induced by light signals. Each of these saturated reactions is located next to the light-responsive reaction in the NFL, suggesting a design principle for daytime dead zone generation. |
format | Online Article Text |
id | pubmed-6396941 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2019 |
publisher | Public Library of Science |
record_format | MEDLINE/PubMed |
spelling | pubmed-63969412019-03-09 A saturated reaction in repressor synthesis creates a daytime dead zone in circadian clocks Uriu, Koichiro Tei, Hajime PLoS Comput Biol Research Article Negative feedback loops (NFLs) for circadian clocks include light-responsive reactions that allow the clocks to shift their phase depending on the timing of light signals. Phase response curves (PRCs) for light signals in various organisms include a time interval called a dead zone where light signals cause no phase shift during daytime. Although the importance of the dead zone for robust light entrainment is known, how the dead zone arises from the biochemical reactions in an NFL underlying circadian gene expression rhythms remains unclear. In addition, the observation that the light-responsive reactions in the NFL vary between organisms raises the question as to whether the mechanism for dead zone formation is common or distinct between different organisms. Here we reveal by mathematical modeling that the saturation of a biochemical reaction in repressor synthesis in an NFL is a common mechanism of daytime dead zone generation. If light signals increase the degradation of a repressor protein, as in Drosophila, the saturation of repressor mRNA transcription nullifies the effect of light signals, generating a dead zone. In contrast, if light signals induce the transcription of repressor mRNA, as in mammals, the saturation of repressor translation can generate a dead zone by cancelling the influence of excess amount of mRNA induced by light signals. Each of these saturated reactions is located next to the light-responsive reaction in the NFL, suggesting a design principle for daytime dead zone generation. Public Library of Science 2019-02-19 /pmc/articles/PMC6396941/ /pubmed/30779745 http://dx.doi.org/10.1371/journal.pcbi.1006787 Text en © 2019 Uriu, Tei http://creativecommons.org/licenses/by/4.0/ This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/) , which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. |
spellingShingle | Research Article Uriu, Koichiro Tei, Hajime A saturated reaction in repressor synthesis creates a daytime dead zone in circadian clocks |
title | A saturated reaction in repressor synthesis creates a daytime dead zone in circadian clocks |
title_full | A saturated reaction in repressor synthesis creates a daytime dead zone in circadian clocks |
title_fullStr | A saturated reaction in repressor synthesis creates a daytime dead zone in circadian clocks |
title_full_unstemmed | A saturated reaction in repressor synthesis creates a daytime dead zone in circadian clocks |
title_short | A saturated reaction in repressor synthesis creates a daytime dead zone in circadian clocks |
title_sort | saturated reaction in repressor synthesis creates a daytime dead zone in circadian clocks |
topic | Research Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6396941/ https://www.ncbi.nlm.nih.gov/pubmed/30779745 http://dx.doi.org/10.1371/journal.pcbi.1006787 |
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