Download MendeleyEngineering the Organophosphorus Acid Anhydrolase Enzyme for Increased Catalytic Efficiency and Broadened Stereospecificity on Russian VX.
Daczkowski, C.M., Pegan, S.D., Harvey, S.P.(2015) Biochemistry 54: 6423-6433
- PubMed: 26418828
- DOI: https://doi.org/10.1021/acs.biochem.5b00624
- Primary Citation of Related Structures:
4ZWO, 4ZWP, 4ZWU - PubMed Abstract:
The enzyme organophosphorus acid anhydrolase (OPAA), from Alteromonas sp. JD6.5, has been shown to rapidly catalyze the hydrolysis of a number of toxic organophosphorus compounds, including several G-type chemical nerve agents. The enzyme was cloned into Escherichia coli and can be produced up to approximately 50% of cellular protein. There have been no previous reports of OPAA activity on VR {Russian VX, O-isobutyl S-[2-(diethylamino)ethyl] methylphosphonothioate}, and our studies reported here show that wild-type OPAA has poor catalytic efficacy toward VR. However, via application of a structurally aided protein engineering approach, significant improvements in catalytic efficiency were realized via optimization of the small pocket within the OPAA's substrate-binding site. This optimization involved alterations at only three amino acid sites resulting in a 30-fold increase in catalytic efficiency toward racemic VR, with a strong stereospecificity toward the P(+) enantiomer. X-ray structures of this mutant as well as one of its predecessors provide potential structural rationales for their effect on the OPAA active site. Additionally, a fourth mutation at a site near the small pocket was found to relax the stereospecificity of the OPAA enzyme. Thus, it allows the altered enzyme to effectively process both VR enantiomers and should be a useful genetic background in which to seek further improvements in OPAA VR activity.
Organizational Affiliation:
Department of Pharmaceutical and Biomedical Sciences, University of Georgia , Athens, Georgia 30602, United States.
