title: The solution structure of the PufX polypeptide from Rhodobacter sphaeroides.
abstract: PufX organizes the photosynthetic reaction centre-light harvesting complex 1 (RC-LH1) core complex of Rhodobacter sphaeroides and facilitates quinol/quinone exchange between the RC and cytochrome bc(1) complexes. The structure of PufX in organic solvent reveals two hydrophobic helices flanked by unstructured termini and connected by a helical bend. The proposed location of basic residues and tryptophans at the membrane interface orients the C-terminal helix along the membrane normal, with the GXXXG motifs in positions unsuitable as direct drivers of dimerisation of the RC-LH1 complex. The N-terminal helix is predicted to extend approximately 40 Anggstrom along the membrane interface.
authors.affiliation: Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK.
authors.forename: Richard B
authors.initials: RB
authors.lastname: Tunnicliffe
authors.forename: Emma C
authors.initials: EC
authors.lastname: Ratcliffe
authors.forename: C Neil
authors.initials: CN
authors.lastname: Hunter
authors.forename: Mike P
authors.initials: MP
authors.lastname: Williamson
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics; D015870:Gene Expression; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D010455:Peptides / Q000737:chemistry* / Q000235:genetics; D017434:Protein Structure, Tertiary; D012242:Rhodobacter sphaeroides / Q000737:chemistry* / Q000235:genetics; D017186:Titrimetry
chemical_list: D001426:Bacterial Proteins; D045342:Light-Harvesting Protein Complexes; D010455:Peptides; C088749:PufX protein, Rhodobacter