title: High-resolution crystal structures of Desulfovibrio vulgaris (Hildenborough) nigerythrin: facile, redox-dependent iron movement, domain interface variability, and peroxidase activity in the rubrerythrins.
abstract: High-resolution crystal structures of Desulfovibrio vulgaris nigerythrin (DvNgr), a member of the rubrerythrin (Rbr) family, demonstrate an approximately 2-A movement of one iron (Fe1) of the diiron site from a carboxylate to a histidine ligand upon conversion of the mixed-valent ([Fe2(II),Fe1(III)]) to diferrous states, even at cryogenic temperatures. This Glu<-->His ligand "toggling" of one iron, which also occurs in DvRbr, thus, appears to be a characteristic feature of Rbr-type diiron sites. Unique features of DvNgr revealed by these structures include redox-induced flipping of a peptide carbonyl that reversibly forms a hydrogen bond to the histidine ligand to Fe1 of the diiron site, an intra-subunit proximal orientation of the rubredoxin-(Rub)-like and diiron domains, and an electron transfer pathway consisting of six covalent and two hydrogen bonds connecting the Rub-like iron with Fe2 of the diiron site. This pathway can account for DvNgr's relatively rapid peroxidase turnover. The characteristic combination of iron sites together with the redox-dependent iron toggling between protein ligands can account for the selectivity of Rbrs for hydrogen peroxide over dioxygen.
authors.affiliation: Department of Chemistry, University of Georgia, Athens, GA 30602, USA.
authors.forename: Ramesh B
authors.initials: RB
authors.lastname: Iyer
authors.forename: Radu
authors.initials: R
authors.lastname: Silaghi-Dumitrescu
authors.forename: Donald M
authors.initials: DM
authors.lastname: Kurtz
authors.forename: William N
authors.initials: WN
authors.lastname: Lanzilotta
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism*; D018360:Crystallography, X-Ray; D016969:Desulfovibrio vulgaris / Q000737:chemistry*; D004579:Electron Transport; D005288:Ferredoxins / Q000378:metabolism*; D006422:Hemerythrin / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D010084:Oxidation-Reduction; D009195:Peroxidase / Q000378:metabolism; D012416:Rubredoxins
chemical_list: D001426:Bacterial Proteins; D005288:Ferredoxins; D006422:Hemerythrin; D012416:Rubredoxins; C079962:nigerythrin protein, Desulfovibrio vulgaris; C055857:rubrerythrins; D007501:Iron; D009195:Peroxidase