A Hard Day's Night: Diatoms continue recycling Photosystem II in the dark
Marine diatoms are photosynthetic, and thrive in environments where light fluctuates. Like all oxygenic photosynthetic organisms diatoms face a light-dependent inactivation of the Photosystem II complexes that photooxidize water to generate biosynthetic reductant. To maintain photosynthesis this ph...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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Frontiers Media S.A.
2016-11-01
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| Series: | Frontiers in Marine Science |
| Subjects: | |
| Online Access: | http://journal.frontiersin.org/Journal/10.3389/fmars.2016.00218/full |
| _version_ | 1819259599374516224 |
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| author | Gang Li Amy Woroch Natalie Donaher Amanda Mary Cockshutt Douglas Andrew Campbell |
| author_facet | Gang Li Amy Woroch Natalie Donaher Amanda Mary Cockshutt Douglas Andrew Campbell |
| author_sort | Gang Li |
| collection | DOAJ |
| description | Marine diatoms are photosynthetic, and thrive in environments where light fluctuates. Like all oxygenic photosynthetic organisms diatoms face a light-dependent inactivation of the Photosystem II complexes that photooxidize water to generate biosynthetic reductant. To maintain photosynthesis this photoinactivation must be countered by slow and metabolically expensive protein turnover, which is light dependent in cyanobacteria and in plants. We tracked daily cycles of the content, synthesis and degradation of Photosystem II, in a small and in a large marine diatom, under low and high growth light levels. We show that, unlike plants, diatoms maintain extensive cycling of Photosystem II proteins even in the dark. Photosystem II protein cycling saturates at low light, and continued cycling in dark periods, using energy from respiration, allows the diatoms to catch up to excess photoinactivation accumulated over the preceding illuminated period. The large diatom suffers only limited photoinactivation of Photosystem II, but cycling of Photosystem II protein exceeds Photosystem II inactivation, so the large diatom recycles functional Photosystem II units before they are inactivated. Through the diel cycle the contents of active Photosystem II centers and Photosystem II proteins change predictably, but are not correlated, generating large changes in the fraction of total PSII that is active at a given time or growth condition. We propose that dark and steady cycling of Photosystem II proteins is driven by the tight integration of chloroplastic and mitochondrial metabolism in diatoms. This ability for baseline, continuous Photosystem II repair could contribute to the success of diatoms in mixed water environments that carry them from illumination to darkness and back. |
| first_indexed | 2024-12-23T19:12:34Z |
| format | Article |
| id | doaj.art-a517d8cf57ce434b8c0de40d05be188b |
| institution | Directory Open Access Journal |
| issn | 2296-7745 |
| language | English |
| last_indexed | 2024-12-23T19:12:34Z |
| publishDate | 2016-11-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Marine Science |
| spelling | doaj.art-a517d8cf57ce434b8c0de40d05be188b2022-12-21T17:34:24ZengFrontiers Media S.A.Frontiers in Marine Science2296-77452016-11-01310.3389/fmars.2016.00218220960A Hard Day's Night: Diatoms continue recycling Photosystem II in the darkGang Li0Amy Woroch1Natalie Donaher2Amanda Mary Cockshutt3Douglas Andrew Campbell4South China Sea Institute of OceanologyMount Allison UniversityMount Allison UniversityMount Allison UniversityMount Allison UniversityMarine diatoms are photosynthetic, and thrive in environments where light fluctuates. Like all oxygenic photosynthetic organisms diatoms face a light-dependent inactivation of the Photosystem II complexes that photooxidize water to generate biosynthetic reductant. To maintain photosynthesis this photoinactivation must be countered by slow and metabolically expensive protein turnover, which is light dependent in cyanobacteria and in plants. We tracked daily cycles of the content, synthesis and degradation of Photosystem II, in a small and in a large marine diatom, under low and high growth light levels. We show that, unlike plants, diatoms maintain extensive cycling of Photosystem II proteins even in the dark. Photosystem II protein cycling saturates at low light, and continued cycling in dark periods, using energy from respiration, allows the diatoms to catch up to excess photoinactivation accumulated over the preceding illuminated period. The large diatom suffers only limited photoinactivation of Photosystem II, but cycling of Photosystem II protein exceeds Photosystem II inactivation, so the large diatom recycles functional Photosystem II units before they are inactivated. Through the diel cycle the contents of active Photosystem II centers and Photosystem II proteins change predictably, but are not correlated, generating large changes in the fraction of total PSII that is active at a given time or growth condition. We propose that dark and steady cycling of Photosystem II proteins is driven by the tight integration of chloroplastic and mitochondrial metabolism in diatoms. This ability for baseline, continuous Photosystem II repair could contribute to the success of diatoms in mixed water environments that carry them from illumination to darkness and back.http://journal.frontiersin.org/Journal/10.3389/fmars.2016.00218/fullThylakoidsphotosystem IThalassiosiraprotein turnoverFtsHPsbA |
| spellingShingle | Gang Li Amy Woroch Natalie Donaher Amanda Mary Cockshutt Douglas Andrew Campbell A Hard Day's Night: Diatoms continue recycling Photosystem II in the dark Frontiers in Marine Science Thylakoids photosystem I Thalassiosira protein turnover FtsH PsbA |
| title | A Hard Day's Night: Diatoms continue recycling Photosystem II in the dark |
| title_full | A Hard Day's Night: Diatoms continue recycling Photosystem II in the dark |
| title_fullStr | A Hard Day's Night: Diatoms continue recycling Photosystem II in the dark |
| title_full_unstemmed | A Hard Day's Night: Diatoms continue recycling Photosystem II in the dark |
| title_short | A Hard Day's Night: Diatoms continue recycling Photosystem II in the dark |
| title_sort | hard day 39 s night diatoms continue recycling photosystem ii in the dark |
| topic | Thylakoids photosystem I Thalassiosira protein turnover FtsH PsbA |
| url | http://journal.frontiersin.org/Journal/10.3389/fmars.2016.00218/full |
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