title: SAD phasing towards structure determination of a thermostable Rieske ferredoxin with a novel stabilizing disulfide bridge.
abstract: Rieske proteins and Rieske ferredoxins are ubiquitous electron-transfer metalloproteins that are characterized by a [2Fe-2S] cluster coordinated by pairs of cysteine and histidine residues. The thermoacidophilic archaeon Acidianus ambivalens contains a Rieske ferredoxin termed RFd2, which has an hitherto unknown additional region of 40-44 residues at the C-terminus with a Cx3C motif that introduces a novel disulfide bond within the Rieske fold. RFd2 was crystallized with the aim of determining its three-dimensional structure in order to understand the contribution of this as yet unique disulfide bridge to the function and stability of RFd2. RFd2 crystals were successively improved, increasing their diffraction to 1.9 Å resolution. Molecular replacement did not solve the RFd2 structure, but a highly multiple in-house diffraction data set collected at the Cu Kα edge led to solution of the phase problem.
authors.affiliation: IBET - Instituto de Biologia Experimental e Tecnológica, Apartado 12, 2780-901 Oeiras, Portugal.
authors.forename: Tiago M
authors.initials: TM
authors.lastname: Bandeiras
authors.forename: Micael C
authors.initials: MC
authors.lastname: Freitas
authors.forename: Dennis
authors.initials: D
authors.lastname: Petrasch
authors.forename: Arnulf
authors.initials: A
authors.lastname: Kletzin
authors.forename: Carlos
authors.initials: C
authors.lastname: Frazão
mesh_terms: D041541:Acidianus; D000595:Amino Acid Sequence; D018360:Crystallography, X-Ray; D004220:Disulfides / Q000737:chemistry*; D014450:Electron Transport Complex III / Q000737:chemistry* / Q000235:genetics; D005288:Ferredoxins / Q000737:chemistry / Q000235:genetics; D008969:Molecular Sequence Data; D017510:Protein Folding; D055550:Protein Stability; D017433:Protein Structure, Secondary
chemical_list: D004220:Disulfides; D005288:Ferredoxins; C037989:Rieske iron-sulfur protein; D014450:Electron Transport Complex III
keywords: Acidianus ambivalens; RFd2; Rieske ferredoxins; SAD; archaea; disulfides; electron transfer