'''STRUCTURE OF PROTOCATECHUATE 3,4-DIOXYGENASE COMPLEXED WITH 3-HYDROXYBENZOATE'''
===STRUCTURE OF PROTOCATECHUATE 3,4-DIOXYGENASE COMPLEXED WITH 3-HYDROXYBENZOATE===
==Overview==
<!--
Protocatechuate 3,4-dioxygenase (3,4-PCD) catalyzes the oxidative ring cleavage of 3,4-dihydroxybenzoate to produce beta-carboxy-cis, cis-muconate. Crystal structures of Pseudomonas putida3,4-PCD [quaternary structure of (alphabetaFe3+)12] complexed with seven competitive inhibitors [3-hydroxyphenylacetate (MHP), 4-hydroxyphenylacetate (PHP), 3-hydroxybenzoate (MHB), 4-hydroxybenzoate (PHB), 3-fluoro-4-hydroxybenzoate (FHB), 3-chloro-4-hydroxybenzoate (CHB), and 3-iodo-4-hydroxybenzoate (IHB)] are reported at 2.0-2.2 A resolution with R-factors of 0. 0.159-0.179. The inhibitors bind in a narrow active site crevasse lined with residues that provide a microenvironment that closely matches the chemical characteristics of the inhibitors. This results in as little as 20% solvent-exposed surface area for the higher-affinity inhibitors (PHB, CHB, and FHB). In uncomplexed 3,4-PCD, the active site Fe3+ is bound at the bottom of the active site crevasse by four endogenous ligands and a solvent molecule (Wat827). The orientations of the endogenous ligands are relatively unperturbed in each inhibitor complex, but the inhibitors themselves bind to or near the iron in a range of positions, all of which perturb the position of Wat827. The three lowest-affinity inhibitors (MHP, PHP, and IHB) yield distorted trigonal bipyramidal iron coordination geometry in which the inhibitor C4-phenolate group displaces the solvent ligand. MHB binds within the active site, but neither its C3-OH group nor the solvent molecule binds to the iron. The C4-phenolate group of the three highest-affinity inhibitors (PHB, CHB, and FHB) coordinates the Fe3+ adjacent to Wat827, resulting in a shift in its position to yield a six-coordinate distorted octahedral geometry. The range of inhibitor orientations may mimic the mechanistically significant stages of substrate binding to 3, 4-PCD. The structure of the final substrate complex is reported in the following paper [Orville, A. M., Lipscomb, J. D., & Ohlendorf, D. H. (1997) Biochemistry 36, 10052-10066].
The line below this paragraph, {{ABSTRACT_PUBMED_9254599}}, adds the Publication Abstract to the page
(as it appears on PubMed at http://www.pubmed.gov), where 9254599 is the PubMed ID number.
-->
{{ABSTRACT_PUBMED_9254599}}
==About this Structure==
==About this Structure==
Line 32:
Line 36:
[[Category: Nonheme]]
[[Category: Nonheme]]
[[Category: Oxidoreductase]]
[[Category: Oxidoreductase]]
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May 4 22:09:06 2008''
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Jul 3 12:59:46 2008''
Revision as of 09:59, 3 July 2008
This article has been automatically seeded. Changes to this page should pertain to the PDB entry only and not to the protein or biomolecule in general.
Structures of competitive inhibitor complexes of protocatechuate 3,4-dioxygenase: multiple exogenous ligand binding orientations within the active site., Orville AM, Elango N, Lipscomb JD, Ohlendorf DH, Biochemistry. 1997 Aug 19;36(33):10039-51. PMID:9254599
