title: Quaternary structure of flavorubredoxin as revealed by synchrotron radiation small-angle X-ray scattering.
abstract: Flavodiiron proteins (FDP) are modular enzymes which function as NO and/or O(2) reductases. Although the majority is composed of two structural domains, the homolog found in Escherichia coli, flavorubredoxin, possesses an extra C-terminal module consisting of a linker and a rubredoxin (Rd) domain necessary for interprotein redox processes. In order to investigate the location of the Rd domain with respect to the flavodiiron structural core, small-angle X-ray scattering was used to construct low-resolution structural models of flavorubredoxin. Scattering patterns from the Rd domain, the FDP core, and full-length flavorubredoxin were collected. The latter two species were found to be tetrameric in solution. Ab initio shape reconstruction and rigid-body modeling indicate a peripheral location for the Rd domains, which appear to have weak contacts with the FDP core. This finding suggests that Rd behaves as an independent domain and is freely available to participate in redox reactions with protein partners.
authors.affiliation: European Molecular Biology Laboratory, Hamburg Outstation, Notkestrasse 85, 22603 Hamburg, Germany.
authors.forename: Maxim V
authors.initials: MV
authors.lastname: Petoukhov
authors.forename: João B
authors.initials: JB
authors.lastname: Vicente
authors.forename: Peter B
authors.initials: PB
authors.lastname: Crowley
authors.forename: Maria Arménia
authors.initials: MA
authors.lastname: Carrondo
authors.forename: Miguel
authors.initials: M
authors.lastname: Teixeira
authors.forename: Dmitri I
authors.initials: DI
authors.lastname: Svergun
mesh_terms: D020134:Catalytic Domain; D029968:Escherichia coli Proteins / Q000737:chemistry*; D008954:Models, Biological; D008958:Models, Molecular; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D053838:Scattering, Small Angle; D017356:Synchrotrons; D014157:Transcription Factors / Q000737:chemistry*; D014961:X-Ray Diffraction / Q000295:instrumentation
chemical_list: D029968:Escherichia coli Proteins; D014157:Transcription Factors; C451400:YgaK protein, E coli