2nxw

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spinqualitylabelsall models 2nxw, resolution 1.50Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

Crystal structure of phenylpyruvate decarboxylase of Azospirillum brasilense

Overview

Phenylpyruvate decarboxylase (PPDC) of Azospirillum brasilense, involved, in the biosynthesis of the plant hormone indole-3-acetic acid and the, antimicrobial compound phenylacetic acid, is a thiamine, diphosphate-dependent enzyme that catalyses the nonoxidative, decarboxylation of indole- and phenylpyruvate. Analogous to yeast pyruvate, decarboxylases, PPDC is subject to allosteric substrate activation, showing sigmoidal v versus [S] plots. The present paper reports the, crystal structure of this enzyme determined at 1.5 A resolution. The, subunit architecture of PPDC is characteristic for other members of the, pyruvate oxidase family, with each subunit consisting of three domains, with an open alpha/beta topology. An active site loop, bearing the, catalytic residues His112 and His113, could not be modelled due to, flexibility. The biological tetramer is best described as an asymmetric, dimer of dimers. A cysteine residue that has been suggested as the site, for regulatory substrate binding in yeast pyruvate decarboxylase is not, conserved, requiring a different mechanism for allosteric substrate, activation in PPDC. Only minor changes occur in the interactions with the, cofactors, thiamine diphosphate and Mg2+, compared to pyruvate, decarboxylase. A greater diversity is observed in the substrate binding, pocket accounting for the difference in substrate specificity. Moreover, a, catalytically important glutamate residue conserved in nearly all, decarboxylases is replaced by a leucine in PPDC. The consequences of these, differences in terms of the catalytic and regulatory mechanism of PPDC are, discussed.

About this Structure

2NXW is a Single protein structure of sequence from Azospirillum brasilense with MG, CL, TPP and GOL as ligands. Active as Phenylpyruvate decarboxylase, with EC number 4.1.1.43 Full crystallographic information is available from OCA.

Reference

The crystal structure of phenylpyruvate decarboxylase from Azospirillum brasilense at 1.5 A resolution. Implications for its catalytic and regulatory mechanism., Versees W, Spaepen S, Vanderleyden J, Steyaert J, FEBS J. 2007 May;274(9):2363-75. Epub 2007 Mar 30. PMID:17403037

Page seeded by OCA on Wed Nov 21 12:58:51 2007