title: NMR analysis of the transient complex between membrane photosystem I and soluble cytochrome c6.
abstract: A structural analysis of the surface areas of cytochrome c(6), responsible for the transient interaction with photosystem I, was performed by NMR transverse relaxation-optimized spectroscopy. The hemeprotein was titrated by adding increasing amounts of the chlorophyllic photosystem, and the NMR spectra of the free and bound protein were analyzed in a comparative way. The NMR signals of cytochrome c(6) residues located at the hydrophobic and electrostatic patches, which both surround the heme cleft, were specifically modified by binding. The backbones of internal residues close to the hydrophobic patch of cytochrome c(6) were also affected, a fact that is ascribed to the conformational changes taking place inside the hemeprotein when interacting with photosystem I. To the best of our knowledge, this is the first structural analysis by NMR spectroscopy of a transient complex between soluble and membrane proteins.
authors.affiliation: Instituto de Bioquímica Vegetal y Fotosíntesis, Universidad de Sevilla y Consejo de Investigaciones Científicas, Américo Vespucio, Spain.
authors.forename: Irene
authors.initials: I
authors.lastname: Díaz-Moreno
authors.forename: Antonio
authors.initials: A
authors.lastname: Díaz-Quintana
authors.forename: Fernando P
authors.initials: FP
authors.lastname: Molina-Heredia
authors.forename: Pedro M
authors.initials: PM
authors.lastname: Nieto
authors.forename: Orjan
authors.initials: O
authors.lastname: Hansson
authors.forename: Miguel A
authors.initials: MA
authors.lastname: De la Rosa
authors.forename: B Göran
authors.initials: BG
authors.lastname: Karlsson
mesh_terms: D002462:Cell Membrane / Q000378:metabolism; D000458:Cyanobacteria / Q000378:metabolism; D045365:Cytochromes c6 / Q000502:physiology*; D004926:Escherichia coli / Q000378:metabolism; D006418:Heme / Q000737:chemistry; D006859:Hydrogen / Q000737:chemistry; D007477:Ions; D008239:Lysine / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D008958:Models, Molecular; D009584:Nitrogen / Q000737:chemistry; D045331:Photosystem I Protein Complex / Q000502:physiology*; D011487:Protein Conformation; D012984:Software; D013053:Spectrophotometry; D055672:Static Electricity
chemical_list: D045365:Cytochromes c6; D007477:Ions; D045331:Photosystem I Protein Complex; D006418:Heme; D006859:Hydrogen; D008239:Lysine; D009584:Nitrogen