2JGL: Crystal structure of mouse acetylcholinesterase inhibited by aged VX and sarin

Citation:
Abstract
Organophosphorus compounds (OPs), such as nerve agents and a group of insecticides, irreversibly inhibit the enzyme acetylcholinesterase (AChE) by a rapid phosphorylation of the catalytic Ser203 residue. The formed AChE-OP conjugate subsequently undergoes an elimination reaction, termed aging, that results in an enzyme completely resistant to oxime-mediated reactivation by medical antidotes. In this study, we present crystal structures of the non-aged and aged complexes between Mus musculus AChE (mAChE) and the nerve agents sarin, VX, and diisopropyl fluorophosphate (DFP) and the OP-based insecticides methamidophos (MeP) and fenamiphos (FeP). Non-aged conjugates of MeP, sarin, and FeP and aged conjugates of MeP, sarin, and VX are very similar to the noninhibited apo conformation of AChE. A minor structural change in the side chain of His447 is observed in the non-aged conjugate of VX. In contrast, an extensive rearrangement of the acyl loop region (residues 287-299) is observed in the non-aged structure of DFP and in the aged structures of DFP and FeP. In the case of FeP, the relatively large substituents of the phosphorus atom are reorganized during aging, providing a structural support of an aging reaction that proceeds through a nucleophilic attack on the phosphorus atom. The FeP aging rate constant is 14 times lower than the corresponding constant for the structurally related OP insecticide MeP, suggesting that tight steric constraints of the acyl pocket loop preclude the formation of a trigonal bipyramidal intermediate.
PDB ID: 2JGLDownload
MMDB ID: 45661
PDB Deposition Date: 2007/2/13
Updated in MMDB: 2007/10
Experimental Method:
x-ray diffraction
Resolution: 2.6  Å
Source Organism:
Similar Structures:
Biological Unit for 2JGL: monomeric; determined by author and by software (PQS)
Molecular Components in 2JGL
Label Count Molecule
Protein (1 molecule)
1
Acetylcholinesterase(Gene symbol: Ache)
Molecule annotation
Chemicals (4 molecules)
1
1
2
1
3
1
4
1
* Click molecule labels to explore molecular sequence information.

Citing MMDB
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