PDBsum entry 4zwp

Hydrolase

PDB id: 4zwp

Contents

Protein chains

422 a.a.

Ligands

M44 ×2

GOL

Metals

_MN ×7

_BA ×3

Waters ×377

References listed in PDB file

Key reference

• Title: Engineering the organophosphorus acid anhydrolase enzyme for increased catalytic efficiency and broadened stereospecificity on russian vx.
• Authors: C.M.Daczkowski, S.D.Pegan, S.P.Harvey.
• Ref.: Biochemistry, 2015, 54, 6423-6433. [DOI no: 10.1021/acs.biochem.5b00624]
• PubMed id: 26418828

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.