title: Cationic state distribution over the chlorophyll d-containing P(D1)/P(D2) pair in photosystem II.
abstract: Most of the chlorophyll (Chl) cofactors in photosystem II (PSII) from Acaryochloris marina are Chld, although a few Chla molecules are also present. To evaluate the possibility that Chla may participate in the P(D1)/P(D2) Chl pair in PSII from A. marina, the P(D1)(•+)/P(D2)(•+) charge ratio was investigated using the PSII crystal structure analyzed at 1.9-Å resolution, while considering all possibilities for the Chld-containing P(D1)/P(D2) pair, i.e., Chld/Chld, Chla/Chld, and Chld/Chla pairs. Chld/Chld and Chla/Chld pairs resulted in a large P(D1)(•+) population relative to P(D2)(•+), as identified in Chla/Chla homodimer pairs in PSII from other species, e.g., Thermosynechococcus elongatus PSII. However, the Chld/Chla pair possessed a P(D1)(•+)/P(D2)(•+) ratio of approximately 50/50, which is in contrast to previous spectroscopic studies on A. marina PSII. The present results strongly exclude the possibility that the Chld/Chla pair serves as P(D1)/P(D2) in A. marina PSII. This article is part of a Special Issue entitled: Photosynthesis Research for Sustainability: from Natural to Artificial.
authors.affiliation: Graduate School of Medicine, Kyoto University, Kyoto, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Saito
authors.forename: Jian-Ren
authors.initials: JR
authors.lastname: Shen
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Ishikita
mesh_terms: D002734:Chlorophyll / Q000737:chemistry*; D010788:Photosynthesis; D045332:Photosystem II Protein Complex / Q000737:chemistry*; D055503:Protein Multimerization
chemical_list: D045332:Photosystem II Protein Complex; D002734:Chlorophyll; C107509:chlorophyll d