title: Structure of the branched-chain aminotransferase from Streptococcus mutans.
abstract: The branched-chain amino-acid aminotransferase from Streptococcus mutans (SmIlvE) was recombinantly expressed in Escherichia coli with high yield. An effective purification protocol was established. A bioactivity assay indicated that SmIlvE had aminotransferase activity. The specific activity of SmIlvE towards amino-acid substrates was found to be as follows (in descending order): Ile > Leu > Val > Trp > Gly. The protein was crystallized using the hanging-drop vapour-diffusion method with PEG 3350 as the primary precipitant. The structure of SmIlvE was solved at 1.97 Å resolution by the molecular-replacement method. Comparison with structures of homologous proteins enabled the identification of conserved structural elements that might play a role in substrate binding. Further work is needed to confirm the interaction between SmIlvE and its substrates by determining the structures of their complexes.
authors.affiliation: Department of Immunology, School of Basic Medical Sciences, Capital Medical University, Beijing 100069, People's Republic of China.
authors.forename: Jing
authors.initials: J
authors.lastname: Ruan
authors.forename: Jia
authors.initials: J
authors.lastname: Hu
authors.forename: Aihong
authors.initials: A
authors.lastname: Yin
authors.forename: Wenqi
authors.initials: W
authors.lastname: Wu
authors.forename: Xuzhen
authors.initials: X
authors.lastname: Cong
authors.forename: Xueting
authors.initials: X
authors.lastname: Feng
authors.forename: Shentao
authors.initials: S
authors.lastname: Li
mesh_terms: D000595:Amino Acid Sequence; D001671:Biochemistry / Q000379:methods; D002138:Calibration; D019295:Computational Biology / Q000379:methods; D003460:Crystallization; D004926:Escherichia coli / Q000378:metabolism; D008968:Molecular Conformation; D008969:Molecular Sequence Data; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry; D017386:Sequence Homology, Amino Acid; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods; D013295:Streptococcus mutans / Q000201:enzymology*; D000637:Transaminases / Q000737:chemistry*; D014961:X-Ray Diffraction
chemical_list: D011994:Recombinant Proteins; D000637:Transaminases; C019798:branched-chain-amino-acid transaminase