The PSI-PSII megacomplex in green plants.
The PSI-PSII megacomplex in green plants.
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绿色植物中的 PSI-PSII 巨型复合物。
DOI：
10.1093/pcp/pcz026
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Tanaka A.
中科院分区：
文献类型：
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作者：
Yokono M;Takabayashi A;Kishimoto J;Fujita T;Iwai M;Murakami A;Akimoto S;Tanaka A.
能量耗散对暴露在阳光直射下的陆地和浅水植物至关重要。几乎所有的绿色植物为了保护光系统反应中心——光系统II （PSII）和光系统I （PSI）而耗散多余的激发能，在强光下继续生长。在我们之前的工作中，我们报道了拟南芥中大约一半的光系统反应中心形成PSI - PSII巨型复合物，并且多余的能量从PSII快速转移到PSI。然而，该巨复合体的生理功能和结构尚不清楚。因此，我们认为光照适应性强的太阳植物比遮荫植物更能积累PSI-PSII巨复合体。此外，太阳植物的PSI有一个深阱来接收激发能，激发能是低能叶绿素，其荧光最大值大于730 nm。这种深阱可以通过改善激发能量耗散来提高PSI的高光耐受性。电子显微图显示，绿色植物中一个PSII二聚体直接夹在两个具有2倍旋转对称的psi之间，形成了PSI-PSII巨复合物的基本形式。这种结构应该能够使能量从PSII快速转移到PSI，并允许PSII中的能量通过PSI中的深阱消散。
Energy dissipation is crucial for land and shallow-water plants exposed to direct sunlight. Almost all green plants dissipate excess excitation energy to protect the photosystem reaction centers, photosystem II (PSII) and photosystem I (PSI), and continue to grow under strong light. In our previous work, we reported that about half of the photosystem reaction centers form a PSI–PSII megacomplex inArabidopsis thaliana, and that the excess energy was transferred from PSII to PSI fast. However, the physiological function and structure of the megacomplex remained unclear. Here, we suggest that high-light adaptable sun-plants accumulate the PSI–PSII megacomplex more than shade-plants. In addition, PSI of sun-plants has a deep trap to receive excitation energy, which is low-energy chlorophylls showing fluorescence maxima longer than 730 nm. This deep trap may increase the high-light tolerance of PSI by improving excitation energy dissipation. Electron micrographs suggest that one PSII dimer is directly sandwiched between two PSIs with 2-fold rotational symmetry in the basic form of the PSI–PSII megacomplex in green plants. This structure should enable fast energy transfer from PSII to PSI and allow energy in PSII to be dissipated via the deep trap in PSI.