Structural biology of oxygen-evolving photosystem II

2015 Fiscal Year Final Research Report

• Project/Area Number: 24687006
• Research Category: Grant-in-Aid for Young Scientists (A)
• Allocation Type: Partial Multi-year Fund
• Research Field: Plant molecular biology/Plant physiology
• Research Institution: Osaka City University
• Principal Investigator: Kawakami Keisuke 大阪市立大学, 複合先端研究機構, 特任准教授 (40619904)
• Project Period (FY): 2012-04-01 – 2016-03-31
• Keywords: 光化学系II / 酸素発生反応 / 酸素発生中心 / ヨウ素イオン / 還元反応

Outline of Final Research Achievements

Plants and cyanobacteria form oxygen molecules required for life on the earth. Tis reaction is performed by light-induced electron transfer and water-splitting reaction of oxygen-evolving center, the so-called Mn4CaO5-cluster in photosystem II (PSII). The chloride ion (Cl-) in PSII is known to be an essential co-factor in the water-splitting reaction, however, the reaction is inhibited when Cl- is replaced with iodine ion (I-). We analyzed the crystal structure of iodine-substituted PSII (I-PSII) to elucidate the inhibition mechanism of the water-splitting reaction by I- and the associated structural changes of the Mn4CaO5-cluster. In this study, we conformed the dynamic structural changes in the Mn4CaO5-cluster and reduction reaction of the cluster upon I- substitution.

Free Research Field

植物生理学, 構造生物化学