title: Structure at 1.3 A resolution of Rhodothermus marinus caa(3) cytochrome c domain.
abstract: The cytochrome c domain of subunit II from the Rhodothermus marinus caa(3) HiPIP:oxygen oxidoreductase, a member of the superfamily of heme-copper-containing terminal oxidases, was produced in Escherichia coli and characterised. The recombinant protein, which shows the same optical absorption and redox properties as the corresponding domain in the holo enzyme, was crystallized and its structure was determined to a resolution of 1.3 A by the multiwavelength anomalous dispersion (MAD) technique using the anomalous dispersion of the heme iron atom. The model was refined to final R(cryst) and R(free) values of 13.9% and 16.7%, respectively. The structure reveals the insertion of two short antiparallel beta-strands forming a small beta-sheet, an interesting variation of the classical all alpha-helical cytochrome c fold. This modification appears to be common to all known caa(3)-type terminal oxidases, as judged by comparative modelling and by analyses of the available amino acid sequences for these enzymes. This is the first high-resolution crystal structure reported for a cytochrome c domain of a caa(3)-type terminal oxidase. The R.marinus caa(3) uses HiPIP as the redox partner. The calculation of the electrostatic potential at the molecular surface of this extra C-terminal domain provides insights into the binding to its redox partner on one side and its interaction with the remaining subunit II on the other side.
authors.affiliation: Department of Molecular Membrane Biology, Max Planck Institute of Biophysics, Marie-Curie-Str. 15, D-60439 Frankfurt am Main, Germany.
authors.forename: Vasundara
authors.initials: V
authors.lastname: Srinivasan
authors.forename: Chitra
authors.initials: C
authors.lastname: Rajendran
authors.forename: Filipa L
authors.initials: FL
authors.lastname: Sousa
authors.forename: Ana M P
authors.initials: AM
authors.lastname: Melo
authors.forename: Lígia M
authors.initials: LM
authors.lastname: Saraiva
authors.forename: Manuela M
authors.initials: MM
authors.lastname: Pereira
authors.forename: Margarida
authors.initials: M
authors.lastname: Santana
authors.forename: Miguel
authors.initials: M
authors.lastname: Teixeira
authors.forename: Hartmut
authors.initials: H
authors.lastname: Michel
mesh_terms: D000595:Amino Acid Sequence; D001412:Bacillus subtilis / Q000201:enzymology; D018360:Crystallography, X-Ray; D003574:Cytochrome c Group / Q000737:chemistry* / Q000378:metabolism; D045264:Cytochromes a / Q000737:chemistry* / Q000378:metabolism; D045266:Cytochromes a3 / Q000737:chemistry* / Q000378:metabolism; D006418:Heme / Q000737:chemistry / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D011487:Protein Conformation; D045245:Rhodothermus / Q000201:enzymology*; D016415:Sequence Alignment; D055672:Static Electricity; D016963:Thermus thermophilus / Q000201:enzymology
chemical_list: D003574:Cytochrome c Group; D045266:Cytochromes a3; C435384:cytochrome caa(3); D006418:Heme; D045264:Cytochromes a