4s2b | pdb_00004s2b

Covalent complex of E. coli transaldolase TalB with tagatose-6-phosphate

spinqualitylabelsall models 4s2b, resolution 1.46Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 4s2b is a 2 chain structure with sequence from Escherichia coli K-12. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 1.46Å Ligands: 44S, SO4 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function TALB_ECOLI Transaldolase is important for the balance of metabolites in the pentose-phosphate pathway.[HAMAP-Rule:MF_00492] Publication Abstract from PubMed Transaldolase B (TalB) and D-fructose-6-phosphate aldolase A (FSAA) from Escherichia coli are C-C bond-forming enzymes. Using kinetic inhibition studies and mass spectrometry, it is shown that enzyme variants of FSAA and TalB that exhibit D-fructose-6-phosphate aldolase activity are inhibited covalently and irreversibly by D-tagatose 6-phosphate (D-T6P), whereas no inhibition was observed for wild-type transaldolase B from E. coli. The crystal structure of the variant TalB(F178Y) with bound sugar phosphate was solved to a resolution of 1.46 A and revealed a novel mode of covalent inhibition. The sugar is bound covalently via its C2 atom to the -NH2 group of the active-site residue Lys132. It is neither bound in the open-chain form nor as the closed-ring form of D-T6P, but has been converted to beta-D-galactofuranose 6-phosphate (D-G6P), a five-membered ring structure. The furanose ring of the covalent adduct is formed via a Heyns rearrangement and subsequent hemiacetal formation. This reaction is facilitated by Tyr178, which is proposed to act as acid-base catalyst. The crystal structure of the inhibitor complex is compared with the structure of the Schiff-base intermediate of TalB(E96Q) formed with the substrate D-fructose 6-phosphate determined to a resolution of 2.20 A. This comparison highlights the differences in stereochemistry at the C4 atom of the ligand as an essential determinant for the formation of the inhibitor adduct in the active site of the enzyme. Novel mode of inhibition by D-tagatose 6-phosphate through a Heyns rearrangement in the active site of transaldolase B variants.,Stellmacher L, Sandalova T, Schneider S, Schneider G, Sprenger GA, Samland AK Acta Crystallogr D Struct Biol. 2016 Apr;72(Pt 4):467-76. doi:, 10.1107/S2059798316001170. Epub 2016 Mar 24. PMID:27050126 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Transaldolase 3D structures

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