title: Photoreduction of the ferredoxin/ferredoxin-NADP(+)-reductase complex by a linked ruthenium polypyridyl chromophore.
abstract: Photosynthetic ferredoxin and its main partner ferredoxin-NADP(+)-reductase (FNR) are key proteins during the photoproduction of reductive power involved in photosynthetic growth. In this work, we used covalent attachment of ruthenium derivatives to different cysteine mutants of ferredoxin to trigger by laser-flash excitation both ferredoxin reduction and subsequent electron transfer from reduced ferredoxin to FNR. Rates and yields of reduction of the ferredoxin [2Fe-2S] cluster by reductively quenched Ru* could be measured for the first time for such a low redox potential protein whereas ferredoxin-FNR electron transfer was characterized in detail for one particular Ru-ferredoxin covalent adduct. For this adduct, the efficiency of FNR single reduction by reduced ferredoxin was close to 100% under both first-order and diffusion-limited second-order conditions. Interprotein intracomplex electron transfer was measured unambiguously for the first time with a fast rate of c. 6500s(-1). Our measurements point out that Ru photosensitizing is a powerful approach to study the functional interactions of ferredoxin with its numerous partners besides FNR.
authors.affiliation: CEA, iBiTec-S/SB2SM, CEA Saclay, 91191 Gif sur Yvette, France; Université Paris-Saclay, I2BC, UMR 9198, 91190 Gif sur Yvette, France.
authors.forename: Annamaria
authors.initials: A
authors.lastname: Quaranta
authors.affiliation: CEA, iBiTec-S/SB2SM, CEA Saclay, 91191 Gif sur Yvette, France.
authors.forename: Bernard
authors.initials: B
authors.lastname: Lagoutte
authors.affiliation: CEA, iBiTec-S/SB2SM, CEA Saclay, 91191 Gif sur Yvette, France.
authors.forename: Julien
authors.initials: J
authors.lastname: Frey
authors.affiliation: CEA, iBiTec-S/SB2SM, CEA Saclay, 91191 Gif sur Yvette, France; Université Paris-Saclay, I2BC, UMR 9198, 91190 Gif sur Yvette, France. Electronic address: pierre.setif@cea.fr.
authors.forename: Pierre
authors.initials: P
authors.lastname: Sétif
mesh_terms: D056831:Coordination Complexes / Q000737:chemistry* / Q000378:metabolism; D004579:Electron Transport; D005287:Ferredoxin-NADP Reductase / Q000737:chemistry / Q000378:metabolism*; D005288:Ferredoxins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D007700:Kinetics; D008027:Light; D016297:Mutagenesis, Site-Directed; D010084:Oxidation-Reduction / Q000528:radiation effects; D054730:Protein Interaction Domains and Motifs / Q000528:radiation effects; D017434:Protein Structure, Tertiary; D012428:Ruthenium / Q000737:chemistry*
chemical_list: D056831:Coordination Complexes; D005288:Ferredoxins; D012428:Ruthenium; D005287:Ferredoxin-NADP Reductase
keywords: Electron transfer; Kinetics; Photochemistry; Photosynthesis; Protein–protein interactions