title: Thioredoxin-mediated reduction of the photosystem I subunit PsaF and activation through oxidation by the interaction partner plastocyanin.
abstract: In the photosynthetic electron-transfer chain, the photosystem I subunit PsaF is involved in the specific binding of plastocyanin. Using fluorescence electrophoresis we show here that the luminal domain of PsaF is a target for thioredoxin-mediated reduction of the Cys residues 8 and 63. Furthermore, by using NMR spectroscopy, we show that the thiolated form of PsaF has a lower affinity towards reduced plastocyanin than when the disulfide bridge is intact. Time-resolved absorbance measurements and fluorescence electrophoresis shows that oxidized plastocyanin can re-oxidize PsaF and thus restore the active form.
authors.affiliation: Department of Chemistry, University of Gothenburg, Gothenburg, Sweden.
authors.forename: Daniel
authors.initials: D
authors.lastname: Farkas
authors.forename: Orjan
authors.initials: O
authors.lastname: Hansson
mesh_terms: D003545:Cysteine / Q000378:metabolism; D004220:Disulfides; D004586:Electrophoresis; D010084:Oxidation-Reduction; D045331:Photosystem I Protein Complex / Q000378:metabolism*; D010970:Plastocyanin / Q000378:metabolism*; D011485:Protein Binding; D013057:Spectrum Analysis; D018724:Spinacia oleracea / Q000201:enzymology*; D013879:Thioredoxins / Q000378:metabolism*
chemical_list: D004220:Disulfides; D045331:Photosystem I Protein Complex; D013879:Thioredoxins; D010970:Plastocyanin; D003545:Cysteine