title: Desulforubrerythrin from Campylobacter jejuni, a novel multidomain protein.
abstract: A novel multidomain metalloprotein from Campylobacter jejuni was overexpressed in Escherichia coli, purified, and extensively characterized. This protein is isolated as a homotetramer of 24-kDa monomers. According to the amino acid sequence, each monomer was predicted to contain three structural domains: an N-terminal desulforedoxin-like domain, followed by a four-helix bundle domain harboring a non-sulfur μ-oxo diiron center, and a rubredoxin-like domain at the C-terminus. The three predicted iron sites were shown to be present and were studied by a combination of UV-vis, EPR, and resonance Raman spectroscopies, which allowed the determination of the electronic and redox properties of each site. The protein contains two FeCys(4) centers with reduction potentials of +240 mV (desulforedoxin-like center) and +185 mV (rubredoxin-like center). These centers are in the high-spin configuration in the as-isolated ferric form. The protein further accommodates a μ-oxo-bridged diiron site with reduction potentials of +270 and +235 mV for the two sequential redox transitions. The protein is rapidly reoxidized by hydrogen peroxide and has a significant NADH-linked hydrogen peroxide reductase activity of 1.8 μmol H(2)O(2) min(-1) mg(-1). Owing to its building blocks and its homology to the rubrerythrin family, the protein is named desulforubrerythrin. It represents a novel example of the large diversity of the organization of domains exhibited by this enzyme family.
authors.affiliation: Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Avenida da República (EAN), 2780-157, Oeiras, Portugal.
authors.forename: Ana F
authors.initials: AF
authors.lastname: Pinto
authors.forename: Smilja
authors.initials: S
authors.lastname: Todorovic
authors.forename: Peter
authors.initials: P
authors.lastname: Hildebrandt
authors.forename: Manabu
authors.initials: M
authors.lastname: Yamazaki
authors.forename: Fumio
authors.initials: F
authors.lastname: Amano
authors.forename: Shizunobu
authors.initials: S
authors.lastname: Igimi
authors.forename: Célia V
authors.initials: CV
authors.lastname: Romão
authors.forename: Miguel
authors.initials: M
authors.lastname: Teixeira
mesh_terms: D000595:Amino Acid Sequence; D016123:Campylobacter jejuni / Q000378:metabolism*; D004578:Electron Spin Resonance Spectroscopy; D006422:Hemerythrin / Q000737:chemistry / Q000378:metabolism*; D006861:Hydrogen Peroxide / Q000378:metabolism; D007506:Iron-Sulfur Proteins / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D012416:Rubredoxins / Q000737:chemistry / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D013059:Spectrum Analysis, Raman
chemical_list: D006422:Hemerythrin; D007506:Iron-Sulfur Proteins; D012416:Rubredoxins; C055857:rubrerythrins; D006861:Hydrogen Peroxide