title: Regulation and Levels of the Thylakoid K+/H+ Antiporter KEA3 Shape the Dynamic Response of Photosynthesis in Fluctuating Light.
abstract: Crop canopies create environments of highly fluctuating light intensities. In such environments, photoprotective mechanisms and their relaxation kinetics have been hypothesized to limit photosynthetic efficiency and therefore crop yield potential. Here, we show that overexpression of the Arabidopsis thylakoid K+/H+antiporter KEA3 accelerates the relaxation of photoprotective energy-dependent quenching after transitions from high to low light in Arabidopsis and tobacco. This, in turn, enhances PSII quantum efficiency in both organisms, supporting that in wild-type plants, residual light energy quenching following a high to low light transition represents a limitation to photosynthetic efficiency in fluctuating light. This finding underscores the potential of accelerating quenching relaxation as a building block for improving photosynthetic efficiency in the field. Additionally, by overexpressing natural KEA3 variants with modification to the C-terminus, we show that KEA3 activity is regulated by a mechanism involving its lumen-localized C-terminus, which lowers KEA3 activity in high light. This regulatory mechanism fine-tunes the balance between photoprotective energy dissipation in high light and maximum quantum yield in low light, likely to be critical for efficient photosynthesis in fluctuating light conditions.
authors.affiliation: Howard Hughes Medical Institute, Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA ute.armbruster78@gmail.com.|Carnegie Institution for Science, Department of Plant Biology, Stanford, CA 94305, USA.|Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, D-14476 Potsdam, Germany.
authors.forename: Ute
authors.initials: U
authors.lastname: Armbruster
authors.affiliation: Howard Hughes Medical Institute, Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA.
authors.forename: Lauriebeth
authors.initials: L
authors.lastname: Leonelli
authors.affiliation: Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, D-14476 Potsdam, Germany.
authors.forename: Viviana
authors.initials: V
authors.lastname: Correa Galvis
authors.affiliation: Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, D-14476 Potsdam, Germany.
authors.forename: Deserah
authors.initials: D
authors.lastname: Strand
authors.affiliation: Howard Hughes Medical Institute, Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA.
authors.forename: Erica H
authors.initials: EH
authors.lastname: Quinn
authors.affiliation: Carnegie Institution for Science, Department of Plant Biology, Stanford, CA 94305, USA.
authors.forename: Martin C
authors.initials: MC
authors.lastname: Jonikas
authors.affiliation: Howard Hughes Medical Institute, Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA.|Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
authors.forename: Krishna K
authors.initials: KK
authors.lastname: Niyogi
mesh_terms: D017398:Alternative Splicing / Q000235:genetics; D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000254:growth & development / Q000502:physiology* / Q000528:radiation effects*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D008027:Light; D010788:Photosynthesis / Q000528:radiation effects*; D045332:Photosystem II Protein Complex / Q000378:metabolism; D027961:Potassium-Hydrogen Antiporters / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020524:Thylakoids / Q000378:metabolism* / Q000528:radiation effects; D014026:Nicotiana / Q000502:physiology / Q000528:radiation effects
chemical_list: D029681:Arabidopsis Proteins; C000589494:KEA3 protein, Arabidopsis; D045332:Photosystem II Protein Complex; D027961:Potassium-Hydrogen Antiporters; D020033:Protein Isoforms; D012333:RNA, Messenger
keywords: Arabidopsis; KEA3; Non-photochemical quenching; PSII quantum efficiency; Thylakoid membrane