title: Different modes of interaction in cyanobacterial complexes of plastocyanin and cytochrome f.
abstract: The highly efficient electron-transfer chain in photosynthesis demonstrates a remarkable variation among organisms in the type of interactions between the soluble electron-transfer protein plastocyanin and it partner cytochrome f. The complex from the cyanobacterium Nostoc sp. PCC 7119 was studied using nuclear magnetic resonance spectroscopy and compared to that of the cyanobacterium Phormidium laminosum. In both systems, the main site of interaction on plastocyanin is the hydrophobic patch. However, the interaction in the Nostoc complex is highly dependent on electrostatics, contrary to that of Phormidium, resulting in a binding constant that is an order of magnitude larger at low ionic strength for the Nostoc complex. Studies of the mixed complexes show that these differences in interactions are mainly attributable to the surface properties of the plastocyanins.
authors.affiliation: Instituto de Bioquímica Vegetal y Fotosíntesis, Universidad de Sevilla y Consejo Superior de Investigaciones Científicas, Américo Vespucio 49, 41092 Sevilla, Spain.
authors.forename: Irene
authors.initials: I
authors.lastname: Díaz-Moreno
authors.forename: Antonio
authors.initials: A
authors.lastname: Díaz-Quintana
authors.forename: Miguel A
authors.initials: MA
authors.lastname: De la Rosa
authors.forename: Peter B
authors.initials: PB
authors.lastname: Crowley
authors.forename: Marcellus
authors.initials: M
authors.lastname: Ubbink
mesh_terms: D000458:Cyanobacteria / Q000737:chemistry* / Q000201:enzymology / Q000378:metabolism*; D045348:Cytochromes f / Q000737:chemistry / Q000378:metabolism*; D057927:Hydrophobic and Hydrophilic Interactions; D008958:Models, Molecular; D046912:Multiprotein Complexes / Q000737:chemistry* / Q000378:metabolism*; D046937:Nostoc / Q000201:enzymology; D019906:Nuclear Magnetic Resonance, Biomolecular; D009994:Osmolar Concentration; D010970:Plastocyanin / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D055672:Static Electricity
chemical_list: D046912:Multiprotein Complexes; D010970:Plastocyanin; D045348:Cytochromes f