每日摘要：線粒體在綠藻的光合作用中發揮重要作用

二月

10

這是郝事之秋陪你的第259天！

Hope everybody can study well and make progress every day!

Mitochondria affect photosynthetic electron transport and photo-sensitivity in a green alga

First author:Veronique Larosa;Università di Padova(帕多瓦大學):Padova, Italy

Corresponding author:Tomas Morosinotto

Photosynthetic organisms (光合生物) use sunlight as the primary source of energy to support their metabolism. In eukaryotes reactions responsible of the conversion of light into chemical energy occur in specific organelles, the chloroplasts. In this study we showed that mitochondria also have a seminal (有重大影響的) influence on cells" energy metabolism and on photosynthetic reactions. This is illustrated by the observation that the strong photosensitivity (感光性) ofChlamydomonas reinhardtii(萊茵衣藻) cells depleted of the chloroplast protein PGRL1 was rescued by the introduction of a mitochondrial mutation affecting respiratory complex I (呼吸複合物I). Functional analysis showed that such a reduced respiratory activity influenced chloroplast electron transport with consequent over-reduction (過度還原) of plastoquinone (質體醌) and donor-side limitation of Photosystem (PS; 光系統) I. As a consequence, damage due to excess light affected more Photosystem (PS) II rather than PSI. Double mutant cells are able to grow under excess illumination (照明), while singlepgrl1are not, thanks to the presence of an efficient repair mechanism of Photosystem II. These results also underline the seminal biological relevance (生物相關性) of the regulation of electron transport reactions (電子傳遞反應) within the photosynthetic complexes. Photosynthetic organisms evolved a strategy to respond to excess light where damage is targeting preferentially to a specific complex, PSII. Cells are able to endure (忍受) extensive damage targeting this complex thanks to an efficient repair mechanisms while, if PSI is affected there are drastic (猛烈的) consequences on growth.

光合生物利用自然光作為其代謝的主要能量來源。在真核生物中，將光能轉化為化學能的過程主要在植物的特殊的器官中進行，就是植物的葉綠體。在本文中，作者的研究顯示植物的線粒體同樣在細胞的能量代謝和光合反應過程中扮演著非常重要的作用。萊茵衣藻細胞具有較強的感光性，在葉綠體蛋白PGRL1被破壞後萊茵衣藻的感光性會減弱，而該過程可以被一個影響呼吸複合物I的線粒體突變所恢復。功能分析顯示呼吸活性的降低可以影響葉綠體電子傳遞，導致質體醌的過度還原以及光系統I供體側的限制。因而，相比於光系統I，過度光照更有可能對光系統II造成更大的影響。雙突變體的細胞可以在過度光照的條件下生長，而單個pgrl1突變則不可以，這主要是歸功於光系統II的高效修復機制。本文的結果顯示了光合複合物間電子傳遞反應的生物相關性。光合生物演化出了一種響應於過度光照的策略，通過優先靶向PSII來避免更多的傷害。由於光系統II高效的修復機制，細胞能夠忍受大範圍的破壞，而如果是PSI受到影響的話，可能會對植物的生長造成劇烈的影響。

通訊：Tomas Morosinotto(https://www.biologia.unipd.it/en/persona/?tx_wfqbe_pi1%5Baccount%5D=tomas-morosinotto)

研究方向：藻類作為材料用作生物燃料的生產；植物從水生到陸生過程中光合作用的演化和適應；類胡蘿蔔素生物合成酶的結構與功能研究。

doi: https://doi.org/10.1104/pp.17.01249

Journal:Plant Physiology

First Published date: 08 February, 2018

（P.S. 歡迎訪問個人博客：http://bbs.sciencenet.cn/u/TickingClock）

（P.S. 封面圖片為綠藻的電鏡照片，來源維基百科）

喜歡這篇文章嗎？立刻分享出去讓更多人知道吧！