Proton Matrix ENDOR studies on Ca2+-depleted and Sr2+-substituted manganese cluster in photosystem II

Hiroki Nagashima, Yoshiki Nakajima, Jian Ren Shen, Hiroyuki Mino

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

Proton matrix ENDOR spectra were measured for Ca2+-depleted and Sr2+-substituted photosystem II (PSII) membrane samples from spinach and core complexes from Thermosynechococcus vulcanus in the S2 state. The ENDOR spectra obtained were similar for untreated PSII from T. vulcanus and spinach, as well as for Ca2+-containing and Sr2+-substituted PSII, indicating that the proton arrangements around the manganese cluster in cyanobacterial and higher plant PSII and Ca2+-containing and Sr2+-substituted PSII are similar in the S2 state, in agreement with the similarity of the crystal structure of both Ca2+-containing and Sr2+-substituted PSII in the S1 state. Nevertheless, slightly different hyperfine separations were found between Ca2+-containing and Sr2+-substituted PSII because of modifications of the water protons ligating to the Sr2+ ion. Importantly, Ca2+ depletion caused the loss of ENDOR signals with a 1.36-MHz separation because of the loss of the water proton W4 connecting Ca2+ and YZ directly. With respect to the crystal structure and the functions of Ca2+ in oxygen evolution, it was concluded that the roles of Ca2+ and Sr2+ involve the maintenance of the hydrogen bond network near the Ca2+ site and electron transfer pathway to the manganese cluster.

Original languageEnglish
Pages (from-to)28166-28174
Number of pages9
JournalJournal of Biological Chemistry
Volume290
Issue number47
DOIs
Publication statusPublished - Nov 20 2015

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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