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Plastidial transporters KEA1 and KEA2 at the inner envelope membrane adjust stromal pH in the dark.
New Phytol. 2021 02; 229(4):2080-2090.NP

Abstract

Photosynthesis and carbon fixation depend critically on the regulation of pH in chloroplast compartments in the daylight and at night. While it is established that an alkaline stroma is required for carbon fixation, it is not known how alkaline stromal pH is formed, maintained or regulated. We tested whether two envelope transporters, AtKEA1 and AtKEA2, directly affected stromal pH in isolated Arabidopsis chloroplasts using the fluorescent probe 2',7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein (BCECF). External K+ -induced alkalinization of the stroma was observed in chloroplasts from wild-type (WT) plants but not from kea1kea2 mutants, suggesting that KEA1 and KEA2 mediate K+ uptake/H+ loss to modulate stromal pH. While light-stimulated alkalinization of the stroma was independent of KEA1 and KEA2, the rate of decay to neutral pH in the dark is delayed in kea1kea2 mutants. However, the dark-induced loss of a pH gradient across the thylakoid membrane was similar in WT and mutant chloroplasts. This indicates that proton influx from the cytosol mediated by envelope K+ /H+ antiporters contributes to adjustment of stromal pH upon light to dark transitions.

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Authors+Show Affiliations

Aranda Sicilia MN
Department of Biochemistry, Cell and Molecular Biology of Plants, Estación Experimental del Zaidín, CSIC, C/ Profesor Albareda 1, Granada, 18008, Spain.
Sánchez Romero ME
Department of Biochemistry, Cell and Molecular Biology of Plants, Estación Experimental del Zaidín, CSIC, C/ Profesor Albareda 1, Granada, 18008, Spain.
Rodríguez Rosales MP
Department of Biochemistry, Cell and Molecular Biology of Plants, Estación Experimental del Zaidín, CSIC, C/ Profesor Albareda 1, Granada, 18008, Spain.
Venema K
Department of Biochemistry, Cell and Molecular Biology of Plants, Estación Experimental del Zaidín, CSIC, C/ Profesor Albareda 1, Granada, 18008, Spain.

MeSH

Arabidopsis ProteinsChloroplastsHydrogen-Ion ConcentrationPlastidsPotassium-Hydrogen Antiporters

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

33111995

Citation

Aranda Sicilia, María Nieves, et al. "Plastidial Transporters KEA1 and KEA2 at the Inner Envelope Membrane Adjust Stromal pH in the Dark." The New Phytologist, vol. 229, no. 4, 2021, pp. 2080-2090.
Aranda Sicilia MN, Sánchez Romero ME, Rodríguez Rosales MP, et al. Plastidial transporters KEA1 and KEA2 at the inner envelope membrane adjust stromal pH in the dark. New Phytol. 2021;229(4):2080-2090.
Aranda Sicilia, M. N., Sánchez Romero, M. E., Rodríguez Rosales, M. P., & Venema, K. (2021). Plastidial transporters KEA1 and KEA2 at the inner envelope membrane adjust stromal pH in the dark. The New Phytologist, 229(4), 2080-2090. https://doi.org/10.1111/nph.17042
Aranda Sicilia MN, et al. Plastidial Transporters KEA1 and KEA2 at the Inner Envelope Membrane Adjust Stromal pH in the Dark. New Phytol. 2021;229(4):2080-2090. PubMed PMID: 33111995.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Plastidial transporters KEA1 and KEA2 at the inner envelope membrane adjust stromal pH in the dark. AU - Aranda Sicilia,María Nieves, AU - Sánchez Romero,María Elena, AU - Rodríguez Rosales,María Pilar, AU - Venema,Kees, Y1 - 2020/11/27/ PY - 2020/09/14/received PY - 2020/10/10/accepted PY - 2020/10/29/pubmed PY - 2021/5/15/medline PY - 2020/10/28/entrez KW - Arabidopsis thaliana KW - BCECF KW - K+/H+ antiport KW - KEA KW - pH KW - plastidial envelope KW - stroma SP - 2080 EP - 2090 JF - The New phytologist JO - New Phytol VL - 229 IS - 4 N2 - Photosynthesis and carbon fixation depend critically on the regulation of pH in chloroplast compartments in the daylight and at night. While it is established that an alkaline stroma is required for carbon fixation, it is not known how alkaline stromal pH is formed, maintained or regulated. We tested whether two envelope transporters, AtKEA1 and AtKEA2, directly affected stromal pH in isolated Arabidopsis chloroplasts using the fluorescent probe 2',7'-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein (BCECF). External K+ -induced alkalinization of the stroma was observed in chloroplasts from wild-type (WT) plants but not from kea1kea2 mutants, suggesting that KEA1 and KEA2 mediate K+ uptake/H+ loss to modulate stromal pH. While light-stimulated alkalinization of the stroma was independent of KEA1 and KEA2, the rate of decay to neutral pH in the dark is delayed in kea1kea2 mutants. However, the dark-induced loss of a pH gradient across the thylakoid membrane was similar in WT and mutant chloroplasts. This indicates that proton influx from the cytosol mediated by envelope K+ /H+ antiporters contributes to adjustment of stromal pH upon light to dark transitions. SN - 1469-8137 UR - https://www.unboundmedicine.com/medline/citation/33111995/Plastidial_transporters_KEA1_and_KEA2_at_the_inner_envelope_membrane_adjust_stromal_pH_in_the_dark_ DB - PRIME DP - Unbound Medicine ER -