title: Structure of a thermophilic cyanobacterial b6f-type Rieske protein.
abstract: The `Rieske protein' PetC is one of the key subunits of the cytochrome b(6)f complex. Its Rieske-type [2Fe-2S] cluster participates in the photosynthetic electron-transport chain. Overexpression and careful structure analysis at 2.0 Å resolution of the extrinsic soluble domain of PetC from the thermophilic cyanobacterium Thermosynechococcus elongatus BP-1 enabled in-depth spectroscopic and structural characterization and suggested novel structural features. In particular, both the protein structure and the positions of the internal water molecules unexpectedly showed a higher similarity to eukaryotic PetCs than to other prokaryotic PetCs. The structure also revealed a deep pocket on the PetC surface which is oriented towards the membrane surface in the whole complex. Its surface properties suggest a binding site for a hydrophobic compound and the complete conservation of the pocket-forming residues in all known PetC sequences indicates the functional importance of this pocket in the cytochrome b(6)f complex.
authors.affiliation: Plant Biochemistry, Ruhr University Bochum, 44780 Bochum, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Veit
authors.forename: Kazuki
authors.initials: K
authors.lastname: Takeda
authors.forename: Yuichi
authors.initials: Y
authors.lastname: Tsunoyama
authors.forename: Dorothea
authors.initials: D
authors.lastname: Rexroth
authors.forename: Matthias
authors.initials: M
authors.lastname: Rögner
authors.forename: Kunio
authors.initials: K
authors.lastname: Miki
mesh_terms: D017124:Conserved Sequence; D018360:Crystallography, X-Ray; D045346:Cytochrome b6f Complex / Q000737:chemistry* / Q000235:genetics; D014450:Electron Transport Complex III / Q000737:chemistry* / Q000235:genetics; D008024:Ligands; D010084:Oxidation-Reduction; D046940:Synechococcus / Q000737:chemistry* / Q000235:genetics
chemical_list: D008024:Ligands; C037989:Rieske iron-sulfur protein; D045346:Cytochrome b6f Complex; D014450:Electron Transport Complex III