Cyclic electron flow and Photosystem II-less photosynthesis.

IF 2.6 4区 生物学 Q2 PLANT SCIENCES
Maria Ermakova, Duncan Fitzpatrick, Anthony W D Larkum
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引用次数: 0

Abstract

Oxygenic photosynthesis is characterised by the cooperation of two photo-driven complexes, Photosystem II (PSII) and Photosystem I (PSI), sequentially linked through a series of redox-coupled intermediates. Divergent evolution has resulted in photosystems exhibiting complementary redox potentials, spanning the range necessary to oxidise water and reduce CO2 within a single system. Catalysing nature's most oxidising reaction to extract electrons from water is a highly specialised task that limits PSII's metabolic function. In contrast, potential electron donors in PSI span a range of redox potentials, enabling it to accept electrons from various metabolic processes. This metabolic flexibility of PSI underpins the capacity of photosynthetic organisms to balance energy supply with metabolic demands, which is key for adaptation to environmental changes. Here, we review the phenomenon of 'PSII-less photosynthesis' where PSI functions independently of PSII by operating cyclic electron flow using electrons derived from non-photochemical reactions. PSII-less photosynthesis enables supercharged ATP production and is employed, for example, by cyanobacteria's heterocysts to host nitrogen fixation and by bundle sheath cells of C4 plants to boost CO2 assimilation. We discuss the energetic benefits of this arrangement and the prospects of utilising it to improve the productivity and stress resilience of photosynthetic organisms.

循环电子流和无光子系统 II 的光合作用。
氧光合作用的特点是两个光驱动复合体--光系统 II(PSII)和光系统 I(PSI)--的合作,它们通过一系列氧化还原耦合中间体依次连接起来。不同的进化使光合系统表现出互补的氧化还原电位,跨越了在单一系统中氧化水和还原二氧化碳所需的范围。催化自然界最具氧化性的反应以从水中提取电子是一项高度专业化的任务,限制了 PSII 的新陈代谢功能。与此相反,PSI 中的潜在电子供体具有不同的氧化还原电位,使其能够接受来自各种代谢过程的电子。PSI 的这种新陈代谢灵活性是光合作用生物体平衡能量供应与新陈代谢需求的基础,也是适应环境变化的关键。在这里,我们回顾了 "无 PSII 光合作用 "现象,即 PSI 利用来自非光化反应的电子进行循环电子流,从而独立于 PSII 发挥作用。无 PSII 光合作用可以产生超强的 ATP,例如,蓝藻的异囊可以利用它来进行固氮,C4 植物的束鞘细胞可以利用它来促进 CO2 同化。我们将讨论这种安排的能量优势,以及利用它提高光合生物的生产力和抗压能力的前景。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
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来源期刊
Functional Plant Biology
Functional Plant Biology 生物-植物科学
CiteScore
5.50
自引率
3.30%
发文量
156
审稿时长
1 months
期刊介绍: Functional Plant Biology (formerly known as Australian Journal of Plant Physiology) publishes papers of a broad interest that advance our knowledge on mechanisms by which plants operate and interact with environment. Of specific interest are mechanisms and signal transduction pathways by which plants adapt to extreme environmental conditions such as high and low temperatures, drought, flooding, salinity, pathogens, and other major abiotic and biotic stress factors. FPB also encourages papers on emerging concepts and new tools in plant biology, and studies on the following functional areas encompassing work from the molecular through whole plant to community scale. FPB does not publish merely phenomenological observations or findings of merely applied significance. Functional Plant Biology is published with the endorsement of the Commonwealth Scientific and Industrial Research Organisation (CSIRO) and the Australian Academy of Science. Functional Plant Biology is published in affiliation with the Federation of European Societies of Plant Biology and in Australia, is associated with the Australian Society of Plant Scientists and the New Zealand Society of Plant Biologists.
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