Plastidial transporters KEA1 and KEA2 at the inner envelope membrane adjust stromal pH in the dark.

Autor: 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.
Jazyk: angličtina
Zdroj: The New phytologist [New Phytol] 2021 Feb; Vol. 229 (4), pp. 2080-2090. Date of Electronic Publication: 2020 Nov 27.
DOI: 10.1111/nph.17042
Abstrakt: 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.
(© 2020 The Authors New Phytologist © 2020 New Phytologist Foundation.)
Databáze: MEDLINE
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