Light-driven CO2 assimilation by photosystem II and its relation to photosynthesis

Photosynthesis is the greatest natural process converting sunlight into chemical energy on a massive scale and maintaining the life on Earth. There are basically two successive stages of oxygenic photosynthesis, of which the light-dependent reactions in photosystem II (PSII), and in photosystem I (PSI), enable the oxidation of H₂O into molecular oxygen, and production of reducing power (NADPH and ATP), while CO₂ assimilation is generally known to take place long after oxygen evolution and NADP⁺ reduction, via light-independent reactions in the stroma.

Meanwhile, there is wide consensus that during light dependent reactions CO₂ (or bicarbonate) is not reduced as a substrate, but plays a unique stimulatory role in O₂ evolution, namely the so-called “bicarbonate effect”. The role of bicarbonate effect as well as the bicarbonate binding sites in PSII have been intensively studied since the 1970s, with some important conclusions reached thus far. However, CO₂ (or bicarbonate) in PSII is thought to only play supporting roles during water oxidation, rather than being “assimilated” by PSII.

Recently, a team of researchers from Dalian University of Technology, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, China, and University of Illinois at Urbana-Champaign, USA, for the first time reported a light-driven CO₂ assimilation by PSII core complex, where the formation of methanol (CH₃OH), along with the oxygen evolution, is validated by in-situ mass spectrometry, gas chromatography and isotopic labeling experiments. Such an unusual CO₂ assimilation is likely to be a simultaneous event along with the usual electron transfer occurring in normal light-independent assimilation. This discovery is extraordinary and is of great significance as it may substantially modify our understanding of the mechanism of photosynthesis. The results were published in Chinese Journal of Catalysis (https://doi.org/10.1016/S1872-2067(22)64170-6).

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About the Journal

Chinese Journal of Catalysis is co-sponsored by Dalian Institute of Chemical Physics, Chinese Academy of Sciences and Chinese Chemical Society, and it is currently published by Elsevier group. This monthly journal publishes in English timely contributions of original and rigorously reviewed manuscripts covering all areas of catalysis. The journal publishes Reviews, Accounts, Communications, Articles, Highlights, Perspectives, and Viewpoints of highly scientific values that help understanding and defining of new concepts in both fundamental issues and practical applications of catalysis. Chinese Journal of Catalysis ranks among the top two journals in Applied Chemistry with a current SCI impact factor of 12.92. The Editors-in-Chief are Profs. Can Li and Tao Zhang.

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