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Regulation of Photosynthetic Light Harvesting Involves Intrathylakoid Lumen pH Sensing by the PsbS Protein*
A bifacial model for the functional interaction of PsbS with photosystem II is proposed, based on the extent of qE inhibition in the mutants, photochemical and nonphotochemical quenching processes of Photosystem II were associated with distinct chlorophyll fluorescence life-time distribution components.
Architecture of a Charge-Transfer State Regulating Light Harvesting in a Plant Antenna Protein
It is proposed that reversible conformational changes in CP29 can “tune” the electronic coupling between the chlorophylls in this dimer, thereby modulating the energy of thechlorophyll-zeaxanthin charge-transfer state and switching on and off the charge- transfer quenching during qE.
Carotenoid-binding proteins of photosystem II.
It was confirmed that the photosystem II reaction centre contains beta-carotene as the only carotenoid, and it was proposed that a role for the minor photosystem-II chlorophyll-a/b proteins is the regulation of energy transfer to the reaction centre.
Light-induced Dissociation of an Antenna Hetero-oligomer Is Needed for Non-photochemical Quenching Induction
PsbS controls the association/dissociation of a five-subunit membrane complex, composed of two monomeric Lhcb proteins (CP29 and CP24) and the trimeric LHCII-M and shows that changes are reversible and do not require protein synthesis/degradation, thus allowing for changes in PSII antenna size and adaptation to rapidly changing environmental conditions.
Zeaxanthin Has Enhanced Antioxidant Capacity with Respect to All Other Xanthophylls in Arabidopsis Leaves and Functions Independent of Binding to PSII Antennae1[C][W]
The results indicate that the antioxidant activity of zeaxanthin, distinct from NPQ, can occur in the absence of PSII light-harvesting complexes.
Analysis of LhcSR3, a Protein Essential for Feedback De-Excitation in the Green Alga Chlamydomonas reinhardtii
To prevent photodamage by excess light, plants use different proteins to sense pH changes and to dissipate excited energy states. In green microalgae, however, the LhcSR3 gene product is able to
Contrasting Behavior of Higher Plant Photosystem I and II Antenna Systems during Acclimation*
Photosystem I light harvesting function was shown to be regulated through different mechanisms like the control of photosystem I to photosystem II ratio and the association or dissociation of Lhcb polypeptides to photoystem I.
Analysis of the Chloroplast Protein Kinase Stt7 during State Transitions
It is proposed that the activity of Stt7 is regulated through its transmembrane domain and that a disulfide bond between the two lumen Cys is essential for its activity.
Zeaxanthin Radical Cation Formation in Minor Light-harvesting Complexes of Higher Plant Antenna*
It is concluded that minor complexes which bind zeaxanthin are sites of charge transfer quenching in vivo and that they can assume Non-quenching and Quenching conformations, the equilibrium LHC(N) ⇆LHC(Q) of which is modulated by the transthylakoid pH gradient, the PsbS protein, and protein-protein interactions.
A zeaxanthin-independent nonphotochemical quenching mechanism localized in the photosystem II core complex.
Reaction-center quenching seems to be a common transient feature during illumination, being replaced by other phenomena (photochemical or antenna quenched and photoinhibition), depending on the balance between light and carbon fixation fluxes.