title: In vivo participation of a high potential iron-sulfur protein as electron donor to the photochemical reaction center of Rubrivivax gelatinosus.
abstract: We have found that the only high redox potential electron transfer component in the soluble fraction of Rubrivivax gelatinosus TG-9 is a high-potential iron-sulfur protein (HiPIP). We demonstrated the participation of this HiPIP in the photoinduced electron transfer both in vivo and in vitro. First, the addition of HiPIP to purified membranes enhanced the rate of re-reduction of the photooxidized reaction center. Second, the photooxidation of HiPIP was observed in intact cells of Ru. gelatinosus TG-9 under anaerobic conditions by EPR and absorption spectroscopies. Analysis of flash-induced absorption changes showed that the equilibration of positive equivalents between the reaction center and HiPIP occurs in less than 1 ms after flash excitation. The complete re-reduction of the photooxidized reaction center is achieved in tens of milliseconds. The turnover of a cyt bc1 is also involved in this reaction, as shown by a slow electrogenic phase of the membrane potential linked to this process.
authors.affiliation: Département de Physiologie Végétale et Ecosystèmes, LBC-C.E. Cadarache, Saint Paul-lez-Durance, France.
authors.forename: B
authors.initials: B
authors.lastname: Schoepp
authors.forename: P
authors.initials: P
authors.lastname: Parot
authors.forename: L
authors.initials: L
authors.lastname: Menin
authors.forename: J
authors.initials: J
authors.lastname: Gaillard
authors.forename: P
authors.initials: P
authors.lastname: Richaud
authors.forename: A
authors.initials: A
authors.lastname: Verméglio
mesh_terms: D004578:Electron Spin Resonance Spectroscopy; D004579:Electron Transport; D014450:Electron Transport Complex III / Q000737:chemistry; D006418:Heme / Q000737:chemistry; D007506:Iron-Sulfur Proteins / Q000737:chemistry* / Q000528:radiation effects; D007700:Kinetics; D010084:Oxidation-Reduction; D010777:Photochemistry; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry* / Q000528:radiation effects; D012244:Rhodospirillaceae / Q000737:chemistry* / Q000528:radiation effects; D012995:Solubility; D013053:Spectrophotometry
chemical_list: D007506:Iron-Sulfur Proteins; D045322:Photosynthetic Reaction Center Complex Proteins; D006418:Heme; D014450:Electron Transport Complex III