title: Coordination between manganese and nitrogen within the ligands in the manganese complexes facilitates the reconstitution of the water-oxidizing complex in manganese-depleted photosystem II preparations.
abstract: The water-oxidizing complex (WOC) within photosystem II (PSII) can be reconstituted with synthetic manganese complexes by a process called photoactivation; however, the key factors affecting the efficiency of synthetic manganese complexes in reconstitution of electron transport and oxygen evolution activity in manganese-depleted PSII remain unclear. In the present study, four complexes with different manganese coordination environments were used to reconstitute the WOC, and an interesting relationship was found between the coordination environment of the manganese atom in the complexes and their efficiency in restoring electron transport and oxygen evolution. If Mn(II) is coordinated to nitrogen atoms within the ligand, it can restore significant rates of electron transport and oxygen evolution; however, if the manganese atom is coordinated only to oxygen atoms instead of nitrogen atoms, it has no capability to restore electron transport and oxygen evolution. So, our results demonstrate that the capability of manganese complexes to reconstitute the WOC is mainly determined by the coordination between nitrogen atoms from ligands and the manganese atom. It is suggested from our results that the ligation between the nitrogen atom and the manganese atom within the manganese complex facilitates the photoligation of the manganese atom to histidyl residues on the apo-protein in manganese-depleted PSII during photoactivation.
authors.affiliation: Photosynthesis Research Center, Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China. lishq@ibcas.ac.cn
authors.forename: Shuqin
authors.initials: S
authors.lastname: Li
authors.forename: Guiying
authors.initials: G
authors.lastname: Chen
authors.forename: Guangye
authors.initials: G
authors.lastname: Han
authors.forename: Lin
authors.initials: L
authors.lastname: Ling
authors.forename: Deguang
authors.initials: D
authors.lastname: Huang
authors.forename: A A
authors.initials: AA
authors.lastname: Khorobrykh
authors.forename: S K
authors.initials: SK
authors.lastname: Zharmukhamedov
authors.forename: Qiutian
authors.initials: Q
authors.lastname: Liu
authors.forename: V V
authors.initials: VV
authors.lastname: Klimov
authors.forename: Tingyun
authors.initials: T
authors.lastname: Kuang
mesh_terms: D005453:Fluorescence; D008024:Ligands; D008345:Manganese / Q000737:chemistry*; D009584:Nitrogen / Q000737:chemistry*; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry; D045332:Photosystem II Protein Complex / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
chemical_list: D008024:Ligands; D045332:Photosystem II Protein Complex; D014867:Water; D008345:Manganese; D009584:Nitrogen; D010100:Oxygen