title: High-resolution structure of the recombinant sweet-tasting protein thaumatin I.
abstract: Thaumatin, an intensely sweet-tasting plant protein, elicits a sweet taste at a concentration of 50 nM. The crystal structure of a recombinant form of thaumatin I produced in the yeast Pichia pastoris has been determined to a resolution of 1.1 Å. The model was refined with anisotropic B parameters and riding H atoms. A comparison of the diffraction data and refinement statistics for recombinant thaumatin I with those for plant thaumatin I revealed no significant differences in the diffraction data. The R values for recombinant thaumatin I and plant thaumatin I (F(o) > 4σ) were 9.11% and 9.91%, respectively, indicating the final model to be of good quality. Notably, the electron-density maps around Asn46 and Ser63, which differ between thaumatin variants, were significantly improved. Furthermore, a number of H atoms became visible in an OMIT map and could be assigned. The high-quality structure of recombinant thaumatin with H atoms should provide details about sweetness determinants in thaumatin and provide valuable insights into the mechanism of its interaction with taste receptors.
authors.affiliation: Division of Food Science and Biotechnology, Graduate School of Agriculture, Kyoto University, Gokasho, Uji, Kyoto, Japan. t2masuda@kais.kyoto-u.ac.jp
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Masuda
authors.forename: Keisuke
authors.initials: K
authors.lastname: Ohta
authors.forename: Bunzo
authors.initials: B
authors.lastname: Mikami
authors.forename: Naofumi
authors.initials: N
authors.lastname: Kitabatake
mesh_terms: D018360:Crystallography, X-Ray; D008958:Models, Molecular; D010843:Pichia / Q000737:chemistry; D010940:Plant Proteins / Q000737:chemistry*; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry; D040681:Structural Homology, Protein
chemical_list: D010940:Plant Proteins; D011994:Recombinant Proteins; C003427:thaumatin protein, plant