論文

査読有り 最終著者 責任著者
2020年11月30日

Involvement of glycogen metabolism in circadian control of UV resistance in cyanobacteria

PLOS Genetics
  • Koji Kawasaki
  • ,
  • Hideo Iwasaki

16
11
開始ページ
e1009230
終了ページ
e1009230
記述言語
掲載種別
研究論文(学術雑誌)
DOI
10.1371/journal.pgen.1009230
出版者・発行元
Public Library of Science (PLoS)

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 <italic>Synechococcus elongatus</italic> 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 <italic>kaiABC</italic> or the DNA-photolyase <italic>phr</italic> 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 <italic>sasA</italic> and <italic>rpaA</italic> and the glycogen degradation enzyme gene <italic>glgP</italic> 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.

リンク情報
DOI
https://doi.org/10.1371/journal.pgen.1009230
URL
https://dx.plos.org/10.1371/journal.pgen.1009230
ID情報
  • DOI : 10.1371/journal.pgen.1009230
  • eISSN : 1553-7404
  • ORCIDのPut Code : 84400298

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