title: Structural characterization of the entire 1.3S subunit of transcarboxylase from Propionibacterium shermanii.
abstract: Transcarboxylase (TC) from Propionibacterium shermanii, a biotin-dependent enzyme, catalyzes the transfer of a carboxyl group from methylmalonyl-CoA to pyruvate in two partial reactions. Within the multisubunit enzyme complex, the 1.3S subunit functions as the carboxyl group carrier. The 1.3S is a 123-amino acid polypeptide (12.6 kDa), to which biotin is covalently attached at Lys 89. We have expressed 1.3S in Escherichia coli with uniform 15N labeling. The backbone structure and dynamics of the protein have been characterized in aqueous solution by three-dimensional heteronuclear nuclear magnetic resonance (NMR) spectroscopy. The secondary structure elements in the protein were identified based on NOE information, secondary chemical shifts, homonuclear 3J(HNHalpha) coupling constants, and amide proton exchange data. The protein contains a predominantly disordered N-terminal half, while the C-terminal half is folded into a compact domain comprising eight beta-strands connected by short loops and turns. The topology of the C-terminal domain is consistent with the fold found in both carboxyl carrier and lipoyl domains, to which this domain has approximately 26-30% sequence similarity.
authors.affiliation: Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, Ohio 44106-4970, USA.
authors.forename: D V
authors.initials: DV
authors.lastname: Reddy
authors.forename: S
authors.initials: S
authors.lastname: Rothemund
authors.forename: B C
authors.initials: BC
authors.lastname: Shenoy
authors.forename: P R
authors.initials: PR
authors.lastname: Carey
authors.forename: F D
authors.initials: FD
authors.lastname: Sönnichsen
mesh_terms: D000595:Amino Acid Sequence; D019878:Carboxyl and Carbamoyl Transferases / Q000737:chemistry*; D004926:Escherichia coli / Q000235:genetics; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D009587:Nitrogen Isotopes / Q000032:analysis; D011424:Propionibacterium / Q000201:enzymology*; D017510:Protein Folding; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000737:chemistry
chemical_list: D009587:Nitrogen Isotopes; D011994:Recombinant Proteins; D019878:Carboxyl and Carbamoyl Transferases; C021580:Methylmalonyl-CoA carboxytransferase