title: Crystal structure of halophilic dodecin: a novel, dodecameric flavin binding protein from Halobacterium salinarum.
abstract: A novel, 68 amino acid long flavoprotein called dodecin has been discovered in the proteome of Halobacterium salinarum by inverse structural genomics. The 1.7 A crystal structure of this protein shows a dodecameric, hollow sphere-like arrangement of the protein subunits. Unlike other known flavoproteins, which bind only monomeric flavin cofactors, the structure of the dodecin oligomer comprises six riboflavin dimers. The dimerization of these riboflavins along the re-faces is mediated by aromatic, antiparallel pi staggering of their isoalloxazine moieties. A unique aromatic tetrade is formed by further sandwiching of the riboflavin dimers between the indole groups of two symmetry-related Trp36s. So far, the dodecins represent the smallest known flavoproteins. Based on the structure and the wide spread occurrences in pathogenic and soil eubacteria, a function in flavin storage or protection against radical or oxygenic stress is suggested for the dodecins.
authors.affiliation: Department of Membrane Biochemistry, Max Planck Institute for Biochemistry, Am Klopferspitz 18a, D-82152, Martinsried, Germany.
authors.forename: Boris
authors.initials: B
authors.lastname: Bieger
authors.forename: Lars-Oliver
authors.initials: LO
authors.lastname: Essen
authors.forename: Dieter
authors.initials: D
authors.lastname: Oesterhelt
mesh_terms: D000595:Amino Acid Sequence; D019843:Archaeal Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics; D018360:Crystallography, X-Ray; D019281:Dimerization; D005415:Flavins / Q000378:metabolism*; D023281:Genomics; D019617:Halobacterium salinarum / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D015394:Molecular Structure; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment
chemical_list: D019843:Archaeal Proteins; D001426:Bacterial Proteins; D005415:Flavins; D021122:Protein Subunits