title: A cryo-crystallographic time course for peroxide reduction by rubrerythrin from Pyrococcus furiosus.
abstract: High-resolution crystal structures of Pyrococcus furiosus rubrerythrin (PfRbr) in the resting (all-ferrous) state and at time points following exposure of the crystals to hydrogen peroxide are reported. This approach was possible because of the relativity slow turnover of PfRbr at room temperature. To this end, we were able to perform time-dependent peroxide treatment of the fully reduced enzyme, under strictly anaerobic conditions, in the crystalline state. In this work we demonstrate, for the first time, that turnover of a thermophilic rubrerythrin results in approximately 2-Å movement of one iron atom in the diiron site from a histidine to a carboxylate ligand. These results confirm that, despite the domain-swapped architecture, the hyperthermophilic rubrerythrins also utilize the classic combination of iron sites together with redox-dependent iron toggling to selectively reduce hydrogen peroxide over dioxygen. In addition, we have identified previously unobserved intermediates in the reaction cycle and observed structural changes that may explain the enzyme precipitation observed for the all-iron form of PfRbr upon oxidation to the all-ferric state.
authors.affiliation: Department of Biochemistry and Molecular Biology, The Center for Metalloenzyme Studies, University of Georgia, Athens, GA 30602, USA.
authors.forename: Bret D
authors.initials: BD
authors.lastname: Dillard
authors.forename: Jonathan M
authors.initials: JM
authors.lastname: Demick
authors.forename: Michael W W
authors.initials: MW
authors.lastname: Adams
authors.forename: William N
authors.initials: WN
authors.lastname: Lanzilotta
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D003080:Cold Temperature; D018360:Crystallography, X-Ray; D006422:Hemerythrin / Q000737:chemistry* / Q000378:metabolism; D007501:Iron / Q000737:chemistry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D015394:Molecular Structure; D010084:Oxidation-Reduction; D010545:Peroxides / Q000737:chemistry*; D011487:Protein Conformation; D020027:Pyrococcus furiosus / Q000737:chemistry*; D012416:Rubredoxins / Q000737:chemistry* / Q000378:metabolism; D013997:Time Factors
chemical_list: D001426:Bacterial Proteins; D006422:Hemerythrin; D010545:Peroxides; D012416:Rubredoxins; C055857:rubrerythrins; D007501:Iron