title: Backbone dynamics of reduced plastocyanin from the cyanobacterium Anabaena variabilis: regions involved in electron transfer have enhanced mobility.
abstract: The dynamics of the backbone of the electron-transfer protein plastocyanin from the cyanobacterium Anabaena variabilis were determined from the (15)N and (13)C(alpha) R(1) and R(2) relaxation rates and steady-state [(1)H]-(15)N and [(1)H]-(13)C nuclear Overhauser effects (NOEs) using the model-free approach. The (13)C relaxation studies were performed using (13)C in natural abundance. Overall, it is found that the protein backbone is rigid. However, the regions that are important for the function of the protein show moderate mobility primarily on the microsecond to millisecond time scale. These regions are the "northern" hydrophobic site close to the metal site, the metal site itself, and the "eastern" face of the molecule. In particular, the mobility of the latter region is interesting in light of recent findings indicating that residues also on the eastern face of plastocyanins from prokaryotes are important for the function of the protein. The study also demonstrates that relaxation rates and NOEs of the (13)C(alpha) nuclei of proteins are valuable supplements to the conventional (15)N relaxation measurements in studies of protein backbone dynamics.
authors.affiliation: Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen Ø, Denmark.
authors.forename: Lixin
authors.initials: L
authors.lastname: Ma
authors.forename: Mathias A S
authors.initials: MA
authors.lastname: Hass
authors.forename: Nanna
authors.initials: N
authors.lastname: Vierick
authors.forename: Søren M
authors.initials: SM
authors.lastname: Kristensen
authors.forename: Jens
authors.initials: J
authors.lastname: Ulstrup
authors.forename: Jens J
authors.initials: JJ
authors.lastname: Led
mesh_terms: D000595:Amino Acid Sequence; D017033:Anabaena / Q000737:chemistry* / Q000378:metabolism; D002247:Carbon Isotopes; D004579:Electron Transport; D008956:Models, Chemical; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009587:Nitrogen Isotopes; D019906:Nuclear Magnetic Resonance, Biomolecular; D010084:Oxidation-Reduction; D010970:Plastocyanin / Q000737:chemistry* / Q000378:metabolism*; D011487:Protein Conformation; D055672:Static Electricity; D013816:Thermodynamics
chemical_list: D002247:Carbon Isotopes; D009587:Nitrogen Isotopes; D010970:Plastocyanin