Proton and Water Transfer Pathways in the S2→ S3Transition of the Water-Oxidizing Complex in Photosystem II: Time-Resolved Infrared Analysis of the Effects of D1-N298A Mutation and NO3-Substitution

Yasutada Okamoto, Yuichiro Shimada, Ryo Nagao, Takumi Noguchi

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)

Abstract

Photosynthetic water oxidation is performed through a light-driven cycle of five intermediates (S0-S4states) in photosystem II (PSII). The S2→ S3transition, which involves concerted water and proton transfer, is a key process for understanding the water oxidation mechanism. Here, to identify the water and proton transfer pathways during the S2→ S3transition, we examined the effects of D1-N298A mutation and NO3-substitution for Cl-, which perturbed the O1 and Cl channels, respectively, on the S2→ S3kinetics using time-resolved infrared spectroscopy. The S2→ S3transition was retarded both upon NO3-substitution and upon D1-N298A mutation, whereas it was unaffected by further NO3-substitution in N298A PSII. The H/D kinetic isotope effect in N298A PSII was relatively small, revealing that water transfer is a rate-limiting step in this mutant. From these results, it was suggested that during the S2→ S3transition, water delivery and proton release occur through the O1 and Cl channels, respectively.

Original languageEnglish
Pages (from-to)6864-6873
Number of pages10
JournalJournal of Physical Chemistry B
Volume125
Issue number25
DOIs
Publication statusPublished - Jul 1 2021
Externally publishedYes

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films
  • Materials Chemistry

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