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THREE-DIMENSIONAL STRUCTURE OF THE ZINC-CONTAINING PHOSPHOTRIESTERASE WITH BOUND SUBSTRATE ANALOG TRIETHYLPHOSPHATE
Structural highlights
FunctionOPD_BREDI Has an unusual substrate specificity for synthetic organophosphate triesters and phosphorofluoridates. All of the phosphate triesters found to be substrates are synthetic compounds. The identity of any naturally occurring substrate for the enzyme is unknown. Has no detectable activity with phosphate monoesters or diesters and no activity as an esterase or protease. It catalyzes the hydrolysis of the insecticide paraoxon at a rate approaching the diffusion limit and thus appears to be optimally evolved for utilizing this synthetic substrate. 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 PubMedPhosphotriesterase (PTE) from Pseudomonas diminuta catalyzes the detoxification of organophosphates such as the widely utilized insecticide paraoxon and the chemical warfare agent sarin. The three-dimensional structure of the enzyme is known from high resolution x-ray crystallographic analyses. Each subunit of the homodimer folds into a so-called TIM barrel, with eight strands of parallel beta-sheet. The two zinc ions required for activity are positioned at the C-terminal portion of the beta-barrel. Here, we describe the three-dimensional structure of PTE complexed with the inhibitor diisopropyl methyl phosphonate, which serves as a mimic for sarin. Additionally, the structure of the enzyme complexed with triethyl phosphate is also presented. In the case of the PTE-diisopropyl methyl phosphonate complex, the phosphoryl oxygen of the inhibitor coordinates to the more solvent-exposed zinc ion (2.5 A), thereby lending support to the presumed catalytic mechanism involving metal coordination of the substrate. In the PTE-triethyl phosphate complex, the phosphoryl oxygen of the inhibitor is positioned at 3.4 A from the more solvent-exposed zinc ion. The two structures described in this report provide additional molecular understanding for the ability of this remarkable enzyme to hydrolyze such a wide range of organophosphorus substrates. The binding of substrate analogs to phosphotriesterase.,Benning MM, Hong SB, Raushel FM, Holden HM J Biol Chem. 2000 Sep 29;275(39):30556-60. PMID:10871616[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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