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Involvement of glycogen metabolism in circadian control of UV resistance in cyanobacteria
Most organisms harbor circadian clocks as endogenous timing systems in order to adapt to daily environmental changes, such as exposure to ultraviolet (UV) light. It has been hypothesized that the circadian clock evolved to prevent UV-sensitive activities, such as DNA replication and cell division, d...
Autores principales: | , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
Public Library of Science
2020
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7728383/ https://www.ncbi.nlm.nih.gov/pubmed/33253146 http://dx.doi.org/10.1371/journal.pgen.1009230 |
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author | Kawasaki, Koji Iwasaki, Hideo |
author_facet | Kawasaki, Koji Iwasaki, Hideo |
author_sort | Kawasaki, Koji |
collection | PubMed |
description | Most organisms harbor circadian clocks as endogenous timing systems in order to adapt to daily environmental changes, such as exposure to ultraviolet (UV) light. It has been hypothesized that the circadian clock evolved to prevent UV-sensitive activities, such as DNA replication and cell division, during the daytime. Indeed, circadian control of UV resistance has been reported in several eukaryotic organisms, from algae to higher organisms, although the underlying mechanisms remain unknown. Here, we demonstrate that the unicellular cyanobacterium Synechococcus elongatus PCC 7942 exhibits a circadian rhythm in resistance to UV-C and UV-B light, which is higher during subjective dawn and lower during subjective dusk. Nullification of the clock gene cluster kaiABC or the DNA-photolyase phr abolished rhythmicity with constitutively lower resistance to UV-C light, and amino acid substitutions of KaiC altered the period lengths of the UV-C resistance rhythm. In order to elucidate the molecular mechanism underlying the circadian regulation of UV-C resistance, transposon insertion mutants that alter UV-C resistance were isolated. Mutations to the master circadian output mediator genes sasA and rpaA and the glycogen degradation enzyme gene glgP abolished circadian rhythms of UV-C resistance with constitutively high UV-C resistance. Combining these results with further experiments using ATP synthesis inhibitor and strains with modified metabolic pathways, we showed that UV-C resistance is weakened by directing more metabolic flux from the glycogen degradation to catabolic pathway such as oxidative pentose phosphate pathway and glycolysis. We suggest glycogen-related metabolism in the dark affects circadian control in UV sensitivity, while the light masks this effect through the photolyase function. |
format | Online Article Text |
id | pubmed-7728383 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2020 |
publisher | Public Library of Science |
record_format | MEDLINE/PubMed |
spelling | pubmed-77283832020-12-17 Involvement of glycogen metabolism in circadian control of UV resistance in cyanobacteria Kawasaki, Koji Iwasaki, Hideo PLoS Genet Research Article Most organisms harbor circadian clocks as endogenous timing systems in order to adapt to daily environmental changes, such as exposure to ultraviolet (UV) light. It has been hypothesized that the circadian clock evolved to prevent UV-sensitive activities, such as DNA replication and cell division, during the daytime. Indeed, circadian control of UV resistance has been reported in several eukaryotic organisms, from algae to higher organisms, although the underlying mechanisms remain unknown. Here, we demonstrate that the unicellular cyanobacterium Synechococcus elongatus PCC 7942 exhibits a circadian rhythm in resistance to UV-C and UV-B light, which is higher during subjective dawn and lower during subjective dusk. Nullification of the clock gene cluster kaiABC or the DNA-photolyase phr abolished rhythmicity with constitutively lower resistance to UV-C light, and amino acid substitutions of KaiC altered the period lengths of the UV-C resistance rhythm. In order to elucidate the molecular mechanism underlying the circadian regulation of UV-C resistance, transposon insertion mutants that alter UV-C resistance were isolated. Mutations to the master circadian output mediator genes sasA and rpaA and the glycogen degradation enzyme gene glgP abolished circadian rhythms of UV-C resistance with constitutively high UV-C resistance. Combining these results with further experiments using ATP synthesis inhibitor and strains with modified metabolic pathways, we showed that UV-C resistance is weakened by directing more metabolic flux from the glycogen degradation to catabolic pathway such as oxidative pentose phosphate pathway and glycolysis. We suggest glycogen-related metabolism in the dark affects circadian control in UV sensitivity, while the light masks this effect through the photolyase function. Public Library of Science 2020-11-30 /pmc/articles/PMC7728383/ /pubmed/33253146 http://dx.doi.org/10.1371/journal.pgen.1009230 Text en © 2020 Kawasaki, Iwasaki 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 Kawasaki, Koji Iwasaki, Hideo Involvement of glycogen metabolism in circadian control of UV resistance in cyanobacteria |
title | Involvement of glycogen metabolism in circadian control of UV resistance in cyanobacteria |
title_full | Involvement of glycogen metabolism in circadian control of UV resistance in cyanobacteria |
title_fullStr | Involvement of glycogen metabolism in circadian control of UV resistance in cyanobacteria |
title_full_unstemmed | Involvement of glycogen metabolism in circadian control of UV resistance in cyanobacteria |
title_short | Involvement of glycogen metabolism in circadian control of UV resistance in cyanobacteria |
title_sort | involvement of glycogen metabolism in circadian control of uv resistance in cyanobacteria |
topic | Research Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7728383/ https://www.ncbi.nlm.nih.gov/pubmed/33253146 http://dx.doi.org/10.1371/journal.pgen.1009230 |
work_keys_str_mv | AT kawasakikoji involvementofglycogenmetabolismincircadiancontrolofuvresistanceincyanobacteria AT iwasakihideo involvementofglycogenmetabolismincircadiancontrolofuvresistanceincyanobacteria |