Identification of a Na+-Binding Site near the Oxygen-Evolving Complex of Spinach Photosystem II.
Biochemistry
; 59(30): 2823-2831, 2020 08 04.
Article
em En
| MEDLINE
| ID: mdl-32650633
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.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Oxigênio
/
Sódio
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Spinacia oleracea
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Complexo de Proteína do Fotossistema II
Tipo de estudo:
Diagnostic_studies
Idioma:
En
Ano de publicação:
2020
Tipo de documento:
Article