Central role of cyclic electron transport around photosystem I in the regulation of photosynthesis.

Toshiharu Shikanai

Journal: Current opinion in biotechnology 2014;26():25-30

PMID: 24679254

Full Text on Elsevier Science View on PubMed

Abstract

Cyclic electron transport around photosystem I generates ATP without the accumulation of NADPH in chloroplasts. In angiosperms, electron transport consists of a PGR5-PGRL1 protein-dependent pathway and a chloroplast NADH dehydrogenase-like complex-dependent pathway. Most likely, the PGR5-PGRL1 pathway corresponds to the cyclic phosphorylation discovered by Arnon and contributes mainly to ΔpH formation in photosynthesis. ATP synthesis utilizes this ΔpH formed by both linear and PSI cyclic electron transport. Furthermore, acidification of the thylakoid lumen downregulates light energy utilization in photosystem II and also electron transport through the cytochrome b6f complex. In the absence of PGR5, chloroplast NDH compensates for the reduced ΔpH formation to some extent. Additionally, proton conductivity is upregulated, probably through ATPase, in pgr5 mutants. The photosynthetic machinery likely forms a complex network to maintain high photosynthesis activity under fluctuating light conditions.

Address: Department of Botany, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan; CREST, Japan Science and Technology Agency, Chiyoda-ku, Tokyo 102-0076, Japan. Electronic address: [email protected].

DOI: 10.1016/j.copbio.2013.08.012

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MeSH Terms: Adenosine Triphosphatases, Adenosine Triphosphate, Antimycin A, Arabidopsis Proteins, Chloroplasts, Cytochrome b6f Complex, Electron Transport, Ferredoxins, Homeostasis, Hydrogen-Ion Concentration, Light, Magnoliopsida, Membrane Proteins, NADH Dehydrogenase, Oxidation-Reduction, Photosynthesis, Photosynthetic Reaction Center Complex Proteins, Photosystem I Protein Complex, Plastoquinone, Protons