Ion antiport accelerates photosynthetic acclimation in fluctuating light environments. Author Ute Armbruster, L Ruby Carrillo, Kees Venema, Lazar Pavlovic, Elisabeth Schmidtmann, Ari Kornfeld, Peter Jahns, Joseph Berry, David Kramer, Martin Jonikas Publication Year 2014 Type Journal Article Abstract Many photosynthetic organisms globally, including crops, forests and algae, must grow in environments where the availability of light energy fluctuates dramatically. How photosynthesis maintains high efficiency despite such fluctuations in its energy source remains poorly understood. Here we show that Arabidopsis thaliana K(+) efflux antiporter (KEA3) is critical for high photosynthetic efficiency under fluctuating light. On a shift from dark to low light, or high to low light, kea3 mutants show prolonged dissipation of absorbed light energy as heat. KEA3 localizes to the thylakoid membrane, and allows proton efflux from the thylakoid lumen by proton/potassium antiport. KEA3's activity accelerates the downregulation of pH-dependent energy dissipation after transitions to low light, leading to faster recovery of high photosystem II quantum efficiency and increased CO2 assimilation. Our results reveal a mechanism that increases the efficiency of photosynthesis under fluctuating light. Keywords Down-Regulation, Light, Adaptation, Physiological, Arabidopsis, Arabidopsis Proteins, Body Temperature Regulation, Environment, Photosynthesis, Photosystem II Protein Complex, Potassium-Hydrogen Antiporters Journal Nat Commun Volume 5 Pages 5439 Date Published 2014 Nov 13 ISSN Number 2041-1723 DOI 10.1038/ncomms6439 Alternate Journal Nat Commun PMCID PMC4243252 PMID 25451040 PubMedPubMed CentralGoogle ScholarBibTeXEndNote X3 XML