PDBsum entry 2wu3

Hydrolase

PDB id: 2wu3

Contents

Protein chains

539 a.a. *

Ligands

HI6 ×2

NAG ×2

P6G

CO3 ×2

Waters ×291

* Residue conservation analysis

PDB id:

2wu3

Name:

Hydrolase

Title:

Crystal structure of mouse acetylcholinesterase in complex with fenamiphos and hi-6

Structure:

Acetylcholinesterase. Chain: a, b. Fragment: catalytic domain, residues 32-574. Engineered: yes. Other_details: fenamiphos covalently bound to ser203

Source:

Mus musculus. Mouse. Organism_taxid: 10090. Expressed in: homo sapiens. Expression_system_taxid: 9606. Expression_system_cell_line: hek293f.

Resolution:

2.70Å R-factor: 0.172 R-free: 0.226

Authors:

A.Hornberg,E.Artursson,R.Warme,Y.-P.Pang,F.Ekstrom

Key ref:

A.Hörnberg et al. (2010). Crystal structures of oxime-bound fenamiphos-acetylcholinesterases: reactivation involving flipping of the His447 ring to form a reactive Glu334-His447-oxime triad. Biochem Pharmacol, 79, 507-515. PubMed id: 19732756

Date:

28-Sep-09 Release date: 20-Oct-09

Protein chains

P21836  (ACES_MOUSE) -  Acetylcholinesterase from Mus musculus

Seq: 614 a.a.

Struc: 539 a.a.*

* PDB and UniProt seqs differ at 3 residue positions (black crosses)

Enzyme reactions

• Enzyme class: E.C.3.1.1.7 - acetylcholinesterase.
• Reaction: acetylcholine + H2O = choline + acetate + H⁺

acetylcholine (Bound ligand (Het Group name = NAG) matches with 41.18% similarity) + H2O = choline (Bound ligand (Het Group name = CO3) matches with 60.00% similarity) + acetate + H(+)

Molecule diagrams generated from .mol files obtained from the KEGG ftp site

reference

Biochem Pharmacol 79:507-515 (2010)

PubMed id: 19732756

Crystal structures of oxime-bound fenamiphos-acetylcholinesterases: reactivation involving flipping of the His447 ring to form a reactive Glu334-His447-oxime triad.

A.Hörnberg, E.Artursson, R.Wärme, Y.P.Pang, F.Ekström.

ABSTRACT

Organophosphorus insecticides and nerve agents inhibit the vital enzyme acetylcholinesterase by covalently bonding to the catalytic serine residue of the enzyme. Oxime-based reactivators, such as [(E)-[1-[(4-carbamoylpyridin-1-ium-1-yl)methoxymethyl]pyridin-2-ylidene]methyl]-oxoazanium dichloride (HI-6) and 1,7-heptylene-bis-N,N'-2-pyridiniumaldoxime dichloride (Ortho-7), restore the organophosphate-inhibited enzymatic activity by cleaving the phosphorous conjugate. In this article, we report the intermolecular interactions between Mus musculus acetylcholinesterase inhibited by the insecticide fenamiphos (fep-mAChE) and HI-6 or Ortho-7 revealed by a combination of crystallography and kinetics. The crystal structures of the two oxime-bound fep-mAChE complexes show that both oximes interact with the peripheral anionic site involving different conformations of Trp286 and different peripheral-site residues (Tyr124 for HI-6 and Tyr72 for Ortho-7). Moreover, residues at catalytic site of the HI-6-bound fep-mAChE complex adopt conformations that are similar to those in the apo mAChE, whereas significant conformational changes are observed for the corresponding residues in the Ortho-7-bound fep-mAChE complex. Interestingly, flipping of the His447 imidazole ring allows the formation of a hydrogen bonding network among the Glu334-His447-Ortho-7 triad, which presumably deprotonates the Ortho-7 oxime hydroxyl group, increases the nucleophilicity of the oxime group, and leads to cleavage of the phosphorous conjugate. These results offer insights into a detailed reactivation mechanism for the oximes and development of improved reactivators.