Computational insights on crystal structures of the oxygen-evolving complex of photosystem II with either Ca2+ or Ca2+ substituted by Sr2+

Leslie Vogt, Mehmed Z. Ertem, Rhitankar Pal, Gary W Brudvig, Victor S. Batista

Research output: Contribution to journalArticle

23 Citations (Scopus)

Abstract

The oxygen-evolving complex of photosystem II can function with either Ca2+ or Sr2+ as the heterocation, but the reason for different turnover rates remains unresolved despite reported X-ray crystal structures for both forms. Using quantum mechanics/molecular mechanics (QM/MM) calculations, we optimize structures with each cation in both the resting state (S1) and in a series of reduced states (S0, S-1, and S-2). Through comparison with experimental data, we determine that the X-ray crystal structures with either Ca2+ or Sr2+ are most consistent with the S-2 state (i.e., Mn4[III,III,III,II] with O4 and O5 protonated). As expected, the QM/MM models show that Ca2+/Sr2+ substitution results in the elongation of the heterocation bonds and the displacement of terminal waters W3 and W4. The optimized structures also show that hydrogen-bonded W5 is displaced in all S states with Sr2+ as the heterocation, suggesting that this water may play a critical role during water oxidation. (Chemical Presented).

Original languageEnglish
Pages (from-to)820-825
Number of pages6
JournalBiochemistry
Volume54
Issue number3
DOIs
Publication statusPublished - Jan 27 2015

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Photosystem II Protein Complex
Mechanics
Molecular mechanics
Crystal structure
Quantum theory
Oxygen
Water
X rays
X-Rays
Molecular Models
Cations
Elongation
Hydrogen
Substitution reactions
Oxidation

ASJC Scopus subject areas

  • Biochemistry
  • Medicine(all)

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Computational insights on crystal structures of the oxygen-evolving complex of photosystem II with either Ca2+ or Ca2+ substituted by Sr2+ . / Vogt, Leslie; Ertem, Mehmed Z.; Pal, Rhitankar; Brudvig, Gary W; Batista, Victor S.

In: Biochemistry, Vol. 54, No. 3, 27.01.2015, p. 820-825.

Research output: Contribution to journalArticle

Vogt, Leslie ; Ertem, Mehmed Z. ; Pal, Rhitankar ; Brudvig, Gary W ; Batista, Victor S. / Computational insights on crystal structures of the oxygen-evolving complex of photosystem II with either Ca2+ or Ca2+ substituted by Sr2+ . In: Biochemistry. 2015 ; Vol. 54, No. 3. pp. 820-825.
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