Comparative investigation of the reaction mechanisms of the organophosphate-degrading phosphotriesterases from Agrobacterium radiobacter (OpdA) and Pseudomonas diminuta (OPH).

Pedroso, Marcelo M., Ely, Fernanda, Mitic, Natasa, Carpenter, Margaret C., Gahan, Lawrence R., Wilcox, Dean E., Larrabee, James L., Ollis, David L. and Schenk, Gerhard (2014) Comparative investigation of the reaction mechanisms of the organophosphate-degrading phosphotriesterases from Agrobacterium radiobacter (OpdA) and Pseudomonas diminuta (OPH).. Journal of Biological Inorganic Chemistry, 19 8: 1263-1275. doi:10.1007/s00775-014-1183-9


Author Pedroso, Marcelo M.
Ely, Fernanda
Mitic, Natasa
Carpenter, Margaret C.
Gahan, Lawrence R.
Wilcox, Dean E.
Larrabee, James L.
Ollis, David L.
Schenk, Gerhard
Title Comparative investigation of the reaction mechanisms of the organophosphate-degrading phosphotriesterases from Agrobacterium radiobacter (OpdA) and Pseudomonas diminuta (OPH).
Journal name Journal of Biological Inorganic Chemistry   Check publisher's open access policy
ISSN 0949-8257
1432-1327
Publication date 2014-08-01
Year available 2014
Sub-type Article (original research)
DOI 10.1007/s00775-014-1183-9
Open Access Status Not yet assessed
Volume 19
Issue 8
Start page 1263
End page 1275
Total pages 13
Place of publication Heidelberg, Germany
Publisher Springer
Language eng
Abstract Metal ion-dependent, organophosphate-degrading enzymes have acquired increasing attention due to their ability to degrade and thus detoxify commonly used pesticides and nerve agents such as sarin. The best characterized of these enzymes are from Pseudomonas diminuta (OPH) and Agrobacterium radiobacter (OpdA). Despite high sequence homology (> 90 % identity) and conserved metal ion coordination these enzymes display considerable variations in substrate specificity, metal ion affinity/preference and reaction mechanism. In this study, we highlight the significance of the presence (OpdA) or absence (OPH) of an extended hydrogen bond network in the active site of these enzymes for the modulation of their catalytic properties. In particular, the second coordination sphere residue in position 254 (Arg in OpdA, His in OPH) is identified as a crucial factor in modulating the substrate preference and binding of these enzymes. Inhibition studies with fluoride also support a mechanism for OpdA whereby the identity of the hydrolysis-initiating nucleophile changes as the pH is altered. The same is not observed for OPH.
Formatted abstract
Metal ion-dependent, organophosphate-degrading enzymes have acquired increasing attention due to their ability to degrade and thus detoxify commonly used pesticides and nerve agents such as sarin. The best characterized of these enzymes are from Pseudomonas diminuta (OPH) and Agrobacterium radiobacter (OpdA). Despite high sequence homology (>90 % identity) and conserved metal ion coordination these enzymes display considerable variations in substrate specificity, metal ion affinity/preference and reaction mechanism. In this study, we highlight the significance of the presence (OpdA) or absence (OPH) of an extended hydrogen bond network in the active site of these enzymes for the modulation of their catalytic properties. In particular, the second coordination sphere residue in position 254 (Arg in OpdA, His in OPH) is identified as a crucial factor in modulating the substrate preference and binding of these enzymes. Inhibition studies with fluoride also support a mechanism for OpdA whereby the identity of the hydrolysis-initiating nucleophile changes as the pH is altered. The same is not observed for OPH
Keyword Binding affinity
Calorimetry
Enzyme Kinetics
Magnetic circular dichroism
Site directed mutagenesis
Q-Index Code C1
Q-Index Status Confirmed Code
Grant ID DP120104263
FT120100694
CHE0848433
Institutional Status UQ
Additional Notes epub ahead of print

Document type: Journal Article
Sub-type: Article (original research)
Collections: Official 2015 Collection
School of Chemistry and Molecular Biosciences
 
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Created: Sat, 16 Aug 2014, 00:28:24 EST by Mrs Louise Nimwegen on behalf of School of Chemistry & Molecular Biosciences