2gn2 | pdb_00002gn2

Crystal structure of tetrameric biodegradative threonine deaminase (TdcB) from Salmonella typhimurium in complex with CMP at 2.5A resolution (Hexagonal form)

spinqualitylabelsall models 2gn2, resolution 2.50Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2gn2 is a 1 chain structure with sequence from Salmonella enterica subsp. enterica serovar typhimurium. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: C5P, NA NonStd Res: LLP Related: 2gn0, 2gn1 Gene: tdcB (Salmonella enterica subsp. enterica serovar Typhimurium) Activity: Threonine ammonia-lyase, with EC number 4.3.1.19 Resources: FirstGlance, OCA, RCSB, PDBsum Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed Two different pyridoxal 5'-phosphate-containing l-threonine deaminases (EC 4.3.1.19), biosynthetic and biodegradative, which catalyze the deamination of l-threonine to alpha-ketobutyrate, are present in Escherichia coli and Salmonella typhimurium. Biodegradative threonine deaminase (TdcB) catalyzes the first reaction in the anaerobic breakdown of l-threonine to propionate. TdcB, unlike the biosynthetic threonine deaminase, is insensitive to l-isoleucine and is activated by AMP. In the present study, TdcB from S. typhimurium was cloned and overexpressed in E. coli. In the presence of AMP or CMP, the recombinant enzyme was converted to the tetrameric form accompanied by significant enzyme activation. To provide insights into ligand-mediated oligomerization and enzyme activation, crystal structures of S. typhimurium TdcB and its complex with CMP were determined. In the native structure, TdcB is in a dimeric form, whereas in the TdcB.CMP complex, it exists in a tetrameric form with 222 symmetry and appears as a dimer of dimers. Tetrameric TdcB binds to four molecules of CMP, two at each of the dimer interfaces. Comparison of the dimer structure in the ligand (CMP)-free and -bound forms suggests that the changes induced by ligand binding at the dimer interface are essential for tetramerization. The differences observed in the tertiary and quaternary structures of TdcB in the absence and presence of CMP appear to account for enzyme activation and increased binding affinity for l-threonine. Comparison of TdcB with related pyridoxal 5'-phosphate-dependent enzymes points to structural and mechanistic similarities. Crystal structures of Salmonella typhimurium biodegradative threonine deaminase and its complex with CMP provide structural insights into ligand-induced oligomerization and enzyme activation.,Simanshu DK, Savithri HS, Murthy MR J Biol Chem. 2006 Dec 22;281(51):39630-41. Epub 2006 Oct 17. PMID:17046821 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Deaminase

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