Abstract
The oxygen-evolving complex (OEC) of photosystem II (PSII) is an oxomanganese cluster composed of four redox-active Mn ions and one redox-inactive Ca2+ ion, with two nearby bound Cl- ions. Sodium is a common counterion of both chloride and hydroxide anions, and a sodium-specific binding site has not been identified near the OEC. Here, we find that the oxygen-evolution activity of spinach PSII increases with Na+ concentration, particularly at high pH. A Na+-specific binding site next to the OEC, becomes available after deprotonation of the D1-H337 amino acid residue, is suggested by the analysis of two recently published PSII cryo-electron microscopy maps in combination with quantum mechanical calculations and multiconformation continuum electrostatics simulations.
Original language | English |
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Pages (from-to) | 2823-2831 |
Number of pages | 9 |
Journal | Biochemistry |
Volume | 59 |
Issue number | 30 |
DOIs | |
Publication status | Published - Aug 4 2020 |
ASJC Scopus subject areas
- Biochemistry