title: Redirecting electron transfer in photosystem II from water to redox-active metal complexes.
abstract: A negatively charged region on the surface of photosystem II (PSII) near Q(A) has been identified as a docking site for cationic exogenous electron acceptors. Oxygen evolution activity, which is inhibited in the presence of the herbicide 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), is recovered by adding Co(III) complexes. Thus, a new electron-transfer pathway is created with Co(III) as the new terminal electron acceptor from Q(A)(-). This binding site is saturated at ∼2.5 mM [Co(III)], which is consistent with the existence of low-affinity interactions with a solvent-exposed surface. This is the first example of a higher plant PSII in which the electron-transfer pathway has been redirected from the normal membrane-associated quinone electron acceptors to water-soluble electron acceptors. The proposed Co(III) binding site may enable efficient collection of electrons generated from photochemical water oxidation by PSII immobilized on an electrode surface.
authors.affiliation: Department of Chemistry, Yale University, New Haven, Connecticut 06520-8107, United States.
authors.forename: Gözde
authors.initials: G
authors.lastname: Ulas
authors.forename: Gary W
authors.initials: GW
authors.lastname: Brudvig
mesh_terms: D001665:Binding Sites; D056831:Coordination Complexes / Q000737:chemistry / Q000378:metabolism*; D004237:Diuron / Q000378:metabolism; D004579:Electron Transport; D006540:Herbicides / Q000378:metabolism; D008958:Models, Molecular; D010084:Oxidation-Reduction; D045332:Photosystem II Protein Complex / Q000737:chemistry / Q000378:metabolism*; D018724:Spinacia oleracea / Q000737:chemistry / Q000378:metabolism*; D014867:Water / Q000737:chemistry / Q000378:metabolism*
chemical_list: D056831:Coordination Complexes; D006540:Herbicides; D045332:Photosystem II Protein Complex; D014867:Water; D004237:Diuron