2j9y

Tryptophan Synthase Q114N mutant in complex with Compound II

spinqualitylabelsall models 2j9y, resolution 1.80Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2j9y is a 2 chain structure. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: FOO, NA Related: 1a50, 1a5a, 1a5b, 1a5s, 1beu, 1bks, 1c29, 1c8v, 1c9d, 1cw2, 1cx9, 1fuy, 1k3u, 1k7e, 1k7f, 1k7x, 1k8x, 1k8y, 1k8z, 1kfb, 1kfc, 1kfe, 1kfj, 1kfk, 1qop, 1qoq, 1tjp, 1ttp, 1ubs, 1wbj, 2cle, 2clf, 2cli, 2clk, 2cll, 2clm, 2clo, 2trs, 2tsy, 2tys, 2wsy, 2j9x, 2j9z Activity: Tryptophan synthase, with EC number 4.2.1.20 Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function [TRPA_SALTY] The alpha subunit is responsible for the aldol cleavage of indoleglycerol phosphate to indole and glyceraldehyde 3-phosphate. [TRPB_SALTY] The beta subunit is responsible for the synthesis of L-tryptophan from indole and L-serine. 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 In the PLP-requiring alpha2beta2 tryptophan synthase complex, recognition of the substrate l-Ser at the beta-site includes a loop structure (residues beta110-115) extensively H-bonded to the substrate alpha-carboxylate. To investigate the relationship of this subsite to catalytic function and to the regulation of substrate channeling, two loop mutants were constructed: betaThr110 --> Val, and betaGln114 --> Asn. The betaT110V mutation greatly impairs both catalytic activity in the beta-reaction, and allosteric communication between the alpha- and beta-sites. The crystal structure of the betaT110V mutant shows that the modified l-Ser carboxylate subsite has altered protein interactions that impair beta-site catalysis and the communication of allosteric signals between the alpha- and beta-sites. Purified betaQ114N consists of two species of mutant protein, one with a reddish color (lambdamax = 506 nm). The reddish species is unable to react with l-Ser. The second betaQ114N species displays significant catalytic activities; however, intermediates obtained on reaction with substrate l-Ser and substrate analogues exhibit perturbed UV/vis absorption spectra. Incubation with l-Ser results in the formation of an inactive species during the first 15 min with lambdamax approximately 320 nm, followed by a slower conversion over 24 h to the species with lambdamax = 506 nm. The 320 and 506 nm species originate from conversion of the alpha-aminoacrylate external aldimine to the internal aldimine and alpha-aminoacrylate, followed by the nucleophilic attack of alpha-aminoacrylate on C-4' of the internal aldimine to give a covalent adduct with PLP. Subsequent treatment with sodium hydroxide releases a modified coenzyme consisting of a vinylglyoxylic acid moiety linked through C-4' to the 4-position of the pyridine ring. We conclude that the shortening of the side chain accompanying the replacement of beta114-Gln by Asn relaxes the steric constraints that prevent this reaction in the wild-type enzyme. This study reveals a new layer of structure-function interactions essential for reaction specificity in tryptophan synthase. BetaQ114N and betaT110V mutations reveal a critically important role of the substrate alpha-carboxylate site in the reaction specificity of tryptophan synthase.,Blumenstein L, Domratcheva T, Niks D, Ngo H, Seidel R, Dunn MF, Schlichting I Biochemistry. 2007 Dec 11;46(49):14100-16. Epub 2007 Nov 16. PMID:18004874 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Tryptophan synthase 3D structures

Proteopedia Page Contributors and Editors (what is this?)

OCA