1k7f
From Proteopedia
OCA (Talk | contribs)
(New page: 200px<br /><applet load="1k7f" size="450" color="white" frame="true" align="right" spinBox="true" caption="1k7f, resolution 1.90Å" /> '''CRYSTAL STRUCTURE OF...)
Next diff →
Revision as of 16:47, 20 November 2007
|
CRYSTAL STRUCTURE OF WILD-TYPE TRYPTOPHAN SYNTHASE COMPLEXED WITH N-[1H-INDOL-3-YL-ACETYL]VALINE ACID
Overview
Tryptophan synthase is a bifunctional alpha(2)beta(2) complex catalyzing, the last two steps of l-tryptophan biosynthesis. The natural substrates of, the alpha-subunit indole- 3-glycerolphosphate and, glyceraldehyde-3-phosphate, and the substrate analogs, indole-3-propanolphosphate and dl-alpha-glycerol-3-phosphate are, allosteric effectors of the beta-subunit activity. It has been shown, recently, that the indole-3-acetyl amino acids indole-3-acetylglycine and, indole-3-acetyl-l-aspartic acid are both alpha-subunit inhibitors and, beta-subunit allosteric effectors, whereas indole-3-acetyl-l-valine is, only an alpha-subunit inhibitor (Marabotti, A., Cozzini, P., and, Mozzarelli, A. (2000) Biochim. Biophys. Acta 1476, 287-299). The crystal, structures of tryptophan synthase complexed with indole-3-acetylglycine, and indole-3-acetyl-l-aspartic acid show that both ligands bind to the, active site such that the carboxylate moiety is positioned similarly as, the phosphate group of the natural substrates. As a consequence, the, residues of the alpha-active site that interact with the ligands are the, same as observed in the indole 3-glycerolphosphate-enzyme complex. Ligand, binding leads to closure of loop alphaL6 of the alpha-subunit, a key, structural element of intersubunit communication. This is in keeping with, the allosteric role played by these compounds. The structure of the enzyme, complex with indole-3-acetyl-l-valine is quite different. Due to the, hydrophobic lateral chain, this molecule adopts a new orientation in the, alpha-active site. In this case, closure of loop alphaL6 is no longer, observed, in agreement with its functioning only as an inhibitor of the, alpha-subunit reaction.
About this Structure
1K7F is a Protein complex structure of sequences from Salmonella typhimurium with IAV and PLP as ligands. Active as Tryptophan synthase, with EC number 4.2.1.20 Full crystallographic information is available from OCA.
Reference
Crystal structures of a new class of allosteric effectors complexed to tryptophan synthase., Weyand M, Schlichting I, Marabotti A, Mozzarelli A, J Biol Chem. 2002 Mar 22;277(12):10647-52. Epub 2001 Dec 26. PMID:11756456
Page seeded by OCA on Tue Nov 20 18:55:11 2007
