title: An evolutionary analysis of the reaction mechanisms of photosystem I reduction by cytochrome c(6) and plastocyanin.
abstract: Photosystem I reduction by the soluble metalloproteins cytochrome c(6) and plastocyanin, which are alternatively synthesized by some photosynthetic organisms depending on the relative availability of copper and iron, has been investigated in cyanobacteria, green algae and plants. The reaction mechanism is classified in three different types on the basis of the affinity of the membrane complex towards its electron donor protein. The role of electrostatic interactions in forming an intermediate transient complex, as well as the structural and functional similarities of cytochrome c(6) and plastocyanin are analysed from an evolutionary point of view. The proposal made is that the heme protein was first "discovered" by nature, when iron was much more abundant on the Earth's surface, and replaced by plastocyanin when copper became available because of the oxidizing conditions of the new atmosphere.
authors.affiliation: Instituto de Bioquímica Vegetal y Fotosíntesis, Universidad de Sevilla y Consejo Superior de Investigaciones Científicas, Américo Vespucio s/n, E-41092 Seville, Spain. marosa@us.es
authors.forename: Miguel A
authors.initials: MA
authors.lastname: De la Rosa
authors.forename: José A
authors.initials: JA
authors.lastname: Navarro
authors.forename: Antonio
authors.initials: A
authors.lastname: Díaz-Quintana
authors.forename: Berta
authors.initials: B
authors.lastname: De la Cerda
authors.forename: Fernando P
authors.initials: FP
authors.lastname: Molina-Heredia
authors.forename: Alexis
authors.initials: A
authors.lastname: Balme
authors.forename: Piedad del S
authors.initials: Pdel S
authors.lastname: Murdoch
authors.forename: Irene
authors.initials: I
authors.lastname: Díaz-Moreno
authors.forename: Raúl V
authors.initials: RV
authors.lastname: Durán
authors.forename: Manuel
authors.initials: M
authors.lastname: Hervás
mesh_terms: D003580:Cytochromes / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D045348:Cytochromes f; D019143:Evolution, Molecular; D008958:Models, Molecular; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010970:Plastocyanin / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D055672:Static Electricity
chemical_list: D003580:Cytochromes; D045322:Photosynthetic Reaction Center Complex Proteins; D010970:Plastocyanin; D045348:Cytochromes f