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Working in tandem, two photosystems in the chloroplast thylakoid membranes produce a linear electron flow from H(2)O to NADP(+). Final electron transfer from ferredoxin to NADP(+) is accomplished by a flavoenzyme ferredoxin:NADP(+) oxidoreductase (FNR). Here we describe TROL (thylakoid rhodanese-like protein), a nuclear-encoded component of thylakoid membranes that is required for tethering of FNR and sustaining efficient linear electron flow (LEF) in vascular plants. TROL consists of two distinct modules; a centrally positioned rhodanese-like domain and a C-terminal hydrophobic FNR binding region. Analysis of Arabidopsis mutant lines indicates that, in the absence of TROL, relative electron transport rates at high-light intensities are severely lowered accompanied with significant increase in non-photochemical quenching (NPQ). Thus, TROL might represent a missing thylakoid membrane docking site for a complex between FNR, ferredoxin and NADP(+). Such association might be necessary for maintaining photosynthetic redox poise and enhancement of the NPQ.
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http://dx.doi.org/10.1111/j.1365-313X.2009.03999.x | DOI Listing |
Curr Issues Mol Biol
August 2025
State Key Laboratory of Nutrient Use and Management, Jinan 250100, China.
Off-white or yellowish shoots are common in tea plants ( L.), and such albino variations are often accompanied by metabolic reprogramming, including increased contents of amino acids and lower levels of polyphenols. Nonetheless, the molecular mechanisms that underlie these albino variations remain to be fully clarified.
View Article and Find Full Text PDFPlant J
August 2025
College of Life Science, Sichuan Agricultural University, Ya'an, 625014, China.
Chlorophyll (Chl) b deficiency leads to vulnerability to high light and oxidative stress in wheat plants, while the detailed mechanism by which Chl b is involved in photoprotection remains unclear in plants. In this study, the roles of thylakoid protein composition and complexes in photosynthetic electron transport, photoprotective responses, and energy dissipation were investigated in Chl b-deficient mutant lines (ANK-32A) and the wild type (WT) of wheat. Compared to the WT, ANK-32A showed higher non-photochemical quenching (NPQ), slower state transitions, and a significant decline in the amount of Lhca1-4, Lhcb1-3, and PSII-LHCII supercomplexes at the early growth stage.
View Article and Find Full Text PDFPlant Physiol
August 2025
Department of Life Science and Technology, Tokyo Institute of Technology, Yokohama 226-8501, Japan.
Land plants have evolved sophisticated regulatory mechanisms to precisely modulate electron flow during photosynthesis that is crucial for protecting the photosynthetic machinery and other cellular components from oxidative photodamage. Non-photochemical quenching (NPQ) serves as a major photoprotective mechanism, dissipating excess absorbed light energy as heat. The chloroplast protein DAY-LENGTH-DEPENDENT DELAYED-GREENING1 (DLDG1), which is specifically conserved in oxygenic phototrophs, plays a pivotal role in controlling NPQ by regulating H+ translocation across the chloroplast envelope membranes.
View Article and Find Full Text PDFPlant Cell Physiol
August 2025
Institute of Plant Science and Resources, Okayama University, Kurashiki, Okayama 710-0046, Japan.
The thylakoid membrane (TM), a defining feature for almost all oxygen-evolving photosynthetic organisms, serves as the structural foundation for light-driven energy conversion. In vascular plants, the TM evolved into a complex architecture composed of single-layered stroma thylakoids and stacked grana thylakoids, enabling the spatial organization of two photosystems (PSII and PSI) to optimize light capture and energy transfer. In addition, two membrane regions, one connecting these two compartments (grana margin) and the other corresponding to the curvature domain in grana, function in dissipating excess energy, balancing electron transfer, and maintaining functional PSII.
View Article and Find Full Text PDFPlant J
August 2025
Graduate School of Arts and Sciences, The University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, 153-8902, Japan.
Photosynthetic organisms alter the lipid composition of the thylakoid membrane in response to environmental conditions. Phosphatidic acid (PA) is the branch point in the biosynthetic pathways of glycolipids and a phospholipid, phosphatidylglycerol (PG). PA and its dephosphorylated form, diacylglycerol (DG), are mutually convertible by PA phosphatase (PAP) and DG kinase (DGK).
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