1kfb

CRYSTAL STRUCTURE OF ALPHAT183V MUTANT OF TRYPTOPHAN SYNTHASE FROM SALMONELLA TYPHIMURIUM WITH Indole Glycerol Phosphate

spinqualitylabelsall models 1kfb, resolution 1.90Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1kfb is a 2 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: IGP, PLP Related: 1k8x Resources: FirstGlance, OCA, RCSB, PDBsum 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 The catalytic activity and substrate channeling of the pyridoxal 5'-phosphate-dependent tryptophan synthase alpha(2)beta(2) complex is regulated by allosteric interactions that modulate the switching of the enzyme between open, low activity and closed, high activity states during the catalytic cycle. The highly conserved alphaThr183 residue is part of loop alphaL6 and is located next to the alpha-active site and forms part of the alpha-beta subunit interface. The role of the interactions of alphaThr183 in alpha-site catalysis and allosteric regulation was investigated by analyzing the kinetics and crystal structures of the isosteric mutant alphaThr183Val. The mutant displays strongly impaired allosteric alpha-beta communication, and the catalytic activity of the alpha-reaction is reduced one hundred fold, whereas the beta-activity is not affected. The structural work establishes that the basis for the missing inter-subunit signaling is the lack of loop alphaL6 closure even in the presence of the alpha-subunit ligands, 3-indolyl-D-glycerol 3'-phosphate, or 3-indolylpropanol 3'-phosphate. The structural basis for the reduced alpha-activity has its origins in the missing hydrogen bond between alphaThr183 and the catalytic residue, alphaAsp60. On the role of alphaThr183 in the allosteric regulation and catalytic mechanism of tryptophan synthase.,Kulik V, Weyand M, Seidel R, Niks D, Arac D, Dunn MF, Schlichting I J Mol Biol. 2002 Dec 6;324(4):677-90. PMID:12460570 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Tryptophan synthase

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