Day/Night Separation of Oxygenic Energy Metabolism and Nuclear DNA Replication in the Unicellular Red Alga <italic toggle="yes">Cyanidioschyzon merolae</italic>

ABSTRACT The transition from G1 to S phase and subsequent nuclear DNA replication in the cells of many species of eukaryotic algae occur predominantly during the evening and night in the absence of photosynthesis; however, little is known about how day/night changes in energy metabolism and cell cyc...

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Autores principales:	Shin-ya Miyagishima, Atsuko Era, Tomohisa Hasunuma, Mami Matsuda, Shunsuke Hirooka, Nobuko Sumiya, Akihiko Kondo, Takayuki Fujiwara
Formato:	article
Lenguaje:	EN
Publicado:	American Society for Microbiology 2019
Materias:	cell cycle Cyanidioschyzon merolae endosymbiosis photosynthetic oxidative stress Microbiology QR1-502
Acceso en línea:	https://doaj.org/article/0d41193050824b5bb88905d2c8c5f446
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spelling	oai:doaj.org-article:0d41193050824b5bb88905d2c8c5f4462021-11-15T16:22:09ZDay/Night Separation of Oxygenic Energy Metabolism and Nuclear DNA Replication in the Unicellular Red Alga <italic toggle="yes">Cyanidioschyzon merolae</italic>10.1128/mBio.00833-192150-7511https://doaj.org/article/0d41193050824b5bb88905d2c8c5f4462019-08-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mBio.00833-19https://doaj.org/toc/2150-7511ABSTRACT The transition from G1 to S phase and subsequent nuclear DNA replication in the cells of many species of eukaryotic algae occur predominantly during the evening and night in the absence of photosynthesis; however, little is known about how day/night changes in energy metabolism and cell cycle progression are coordinated and about the advantage conferred by the restriction of S phase to the night. Using a synchronous culture of the unicellular red alga Cyanidioschyzon merolae, we found that the levels of photosynthetic and respiratory activities peak during the morning and then decrease toward the evening and night, whereas the pathways for anaerobic consumption of pyruvate, produced by glycolysis, are upregulated during the evening and night as reported recently in the green alga Chlamydomonas reinhardtii. Inhibition of photosynthesis by 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) largely reduced respiratory activity and the amplitude of the day/night rhythm of respiration, suggesting that the respiratory rhythm depends largely on photosynthetic activity. Even when the timing of G1/S-phase transition was uncoupled from the day/night rhythm by depletion of retinoblastoma-related (RBR) protein, the same patterns of photosynthesis and respiration were observed, suggesting that cell cycle progression and energy metabolism are regulated independently. Progression of the S phase under conditions of photosynthesis elevated the frequency of nuclear DNA double-strand breaks (DSB). These results suggest that the temporal separation of oxygenic energy metabolism, which causes oxidative stress, from nuclear DNA replication reduces the risk of DSB during cell proliferation in C. merolae. IMPORTANCE Eukaryotes acquired chloroplasts through an endosymbiotic event in which a cyanobacterium or a unicellular eukaryotic alga was integrated into a previously nonphotosynthetic eukaryotic cell. Photosynthesis by chloroplasts enabled algae to expand their habitats and led to further evolution of land plants. However, photosynthesis causes greater oxidative stress than mitochondrion-based respiration. In seed plants, cell division is restricted to nonphotosynthetic meristematic tissues and populations of photosynthetic cells expand without cell division. Thus, seemingly, photosynthesis is spatially sequestrated from cell proliferation. In contrast, eukaryotic algae possess photosynthetic chloroplasts throughout their life cycle. Here we show that oxygenic energy conversion (daytime) and nuclear DNA replication (night time) are temporally sequestrated in C. merolae. This sequestration enables “safe” proliferation of cells and allows coexistence of chloroplasts and the eukaryotic host cell, as shown in yeast, where mitochondrial respiration and nuclear DNA replication are temporally sequestrated to reduce the mutation rate.Shin-ya MiyagishimaAtsuko EraTomohisa HasunumaMami MatsudaShunsuke HirookaNobuko SumiyaAkihiko KondoTakayuki FujiwaraAmerican Society for Microbiologyarticlecell cycleCyanidioschyzon merolaeendosymbiosisphotosynthetic oxidative stressMicrobiologyQR1-502ENmBio, Vol 10, Iss 4 (2019)
institution	DOAJ
collection	DOAJ
language	EN
topic	cell cycle Cyanidioschyzon merolae endosymbiosis photosynthetic oxidative stress Microbiology QR1-502
spellingShingle	cell cycle Cyanidioschyzon merolae endosymbiosis photosynthetic oxidative stress Microbiology QR1-502 Shin-ya Miyagishima Atsuko Era Tomohisa Hasunuma Mami Matsuda Shunsuke Hirooka Nobuko Sumiya Akihiko Kondo Takayuki Fujiwara Day/Night Separation of Oxygenic Energy Metabolism and Nuclear DNA Replication in the Unicellular Red Alga <italic toggle="yes">Cyanidioschyzon merolae</italic>
description	ABSTRACT The transition from G1 to S phase and subsequent nuclear DNA replication in the cells of many species of eukaryotic algae occur predominantly during the evening and night in the absence of photosynthesis; however, little is known about how day/night changes in energy metabolism and cell cycle progression are coordinated and about the advantage conferred by the restriction of S phase to the night. Using a synchronous culture of the unicellular red alga Cyanidioschyzon merolae, we found that the levels of photosynthetic and respiratory activities peak during the morning and then decrease toward the evening and night, whereas the pathways for anaerobic consumption of pyruvate, produced by glycolysis, are upregulated during the evening and night as reported recently in the green alga Chlamydomonas reinhardtii. Inhibition of photosynthesis by 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) largely reduced respiratory activity and the amplitude of the day/night rhythm of respiration, suggesting that the respiratory rhythm depends largely on photosynthetic activity. Even when the timing of G1/S-phase transition was uncoupled from the day/night rhythm by depletion of retinoblastoma-related (RBR) protein, the same patterns of photosynthesis and respiration were observed, suggesting that cell cycle progression and energy metabolism are regulated independently. Progression of the S phase under conditions of photosynthesis elevated the frequency of nuclear DNA double-strand breaks (DSB). These results suggest that the temporal separation of oxygenic energy metabolism, which causes oxidative stress, from nuclear DNA replication reduces the risk of DSB during cell proliferation in C. merolae. IMPORTANCE Eukaryotes acquired chloroplasts through an endosymbiotic event in which a cyanobacterium or a unicellular eukaryotic alga was integrated into a previously nonphotosynthetic eukaryotic cell. Photosynthesis by chloroplasts enabled algae to expand their habitats and led to further evolution of land plants. However, photosynthesis causes greater oxidative stress than mitochondrion-based respiration. In seed plants, cell division is restricted to nonphotosynthetic meristematic tissues and populations of photosynthetic cells expand without cell division. Thus, seemingly, photosynthesis is spatially sequestrated from cell proliferation. In contrast, eukaryotic algae possess photosynthetic chloroplasts throughout their life cycle. Here we show that oxygenic energy conversion (daytime) and nuclear DNA replication (night time) are temporally sequestrated in C. merolae. This sequestration enables “safe” proliferation of cells and allows coexistence of chloroplasts and the eukaryotic host cell, as shown in yeast, where mitochondrial respiration and nuclear DNA replication are temporally sequestrated to reduce the mutation rate.
format	article
author	Shin-ya Miyagishima Atsuko Era Tomohisa Hasunuma Mami Matsuda Shunsuke Hirooka Nobuko Sumiya Akihiko Kondo Takayuki Fujiwara
author_facet	Shin-ya Miyagishima Atsuko Era Tomohisa Hasunuma Mami Matsuda Shunsuke Hirooka Nobuko Sumiya Akihiko Kondo Takayuki Fujiwara
author_sort	Shin-ya Miyagishima
title	Day/Night Separation of Oxygenic Energy Metabolism and Nuclear DNA Replication in the Unicellular Red Alga <italic toggle="yes">Cyanidioschyzon merolae</italic>
title_short	Day/Night Separation of Oxygenic Energy Metabolism and Nuclear DNA Replication in the Unicellular Red Alga <italic toggle="yes">Cyanidioschyzon merolae</italic>
title_full	Day/Night Separation of Oxygenic Energy Metabolism and Nuclear DNA Replication in the Unicellular Red Alga <italic toggle="yes">Cyanidioschyzon merolae</italic>
title_fullStr	Day/Night Separation of Oxygenic Energy Metabolism and Nuclear DNA Replication in the Unicellular Red Alga <italic toggle="yes">Cyanidioschyzon merolae</italic>
title_full_unstemmed	Day/Night Separation of Oxygenic Energy Metabolism and Nuclear DNA Replication in the Unicellular Red Alga <italic toggle="yes">Cyanidioschyzon merolae</italic>
title_sort	day/night separation of oxygenic energy metabolism and nuclear dna replication in the unicellular red alga <italic toggle="yes">cyanidioschyzon merolae</italic>
publisher	American Society for Microbiology
publishDate	2019
url	https://doaj.org/article/0d41193050824b5bb88905d2c8c5f446
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Day/Night Separation of Oxygenic Energy Metabolism and Nuclear DNA Replication in the Unicellular Red Alga <italic toggle="yes">Cyanidioschyzon merolae</italic>

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