Artículo
A Single Arginyl Residue in Plastocyanin and in Cytochrome c6 from the Cyanobacterium Anabaenasp. PCC 7119 Is Required for Efficient Reduction of Photosystem I
Autor/es | Molina Heredia, Fernando Publio
Hervás Morón, Manuel Navarro Carruesco, José Antonio Rosa Acosta, Miguel Ángel de la |
Departamento | Universidad de Sevilla. Departamento de Bioquímica Vegetal y Biología Molecular |
Fecha de publicación | 2001 |
Fecha de depósito | 2022-06-02 |
Publicado en |
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Resumen | Positively charged plastocyanin from Anabaena sp. PCC 7119 was investigated by site-directed mutagenesis. The reactivity of its mutants toward photosystem I was analyzed by laser flash spectroscopy. Replacement of arginine ... Positively charged plastocyanin from Anabaena sp. PCC 7119 was investigated by site-directed mutagenesis. The reactivity of its mutants toward photosystem I was analyzed by laser flash spectroscopy. Replacement of arginine at position 88, which is adjacent to the copper ligand His-87, by glutamine and, in particular, by glutamate makes plastocyanin reduce its availability for transferring electrons to photosystem I. Such a residue in the copper protein thus appears to be isofunctional with Arg-64 (which is close to the heme group) in cytochrome c6 from Anabaena(Molina-Heredia, F. P., Dı́az-Quintana, A., Hervás, M., Navarro, J. A., and De la Rosa, M. A. (1999)J. Biol. Chem. 274, 33565–33570) and Synechocystis (De la Cerda, B., Dı́az-Quintana, A., Navarro, J. A., Hervás, M., and De la Rosa, M. A. (1999) J. Biol. Chem. 274, 13292–13297). Other mutations concern specific residues of plastocyanin either at its positively charged east face (D49K, H57A, H57E, K58A, K58E, Y83A, and Y83F) or at its north hydrophobic pole (L12A, K33A, and K33E). Mutations altering the surface electrostatic potential distribution allow the copper protein to modulate its kinetic efficiency: the more positively charged the interaction site, the higher the rate constant. Whereas replacement of Tyr-83 by either alanine or phenylalanine has no effect on the kinetics of photosystem I reduction, Leu-12 and Lys-33 are essential for the reactivity of plastocyanin. |
Cita | Molina Heredia, F.P., Hervás Morón, M., Navarro Carruesco, J.A. y Rosa Acosta, M.Á.d.l. (2001). A Single Arginyl Residue in Plastocyanin and in Cytochrome c6 from the Cyanobacterium Anabaenasp. PCC 7119 Is Required for Efficient Reduction of Photosystem I. Journal of Biological Chemistry, 276 (1), 601-605. |
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