2XMG

G117H mutant of human butyrylcholinesterase in complex with VX

Summary for 2XMG

• Entry DOI: 10.2210/pdb2xmg/pdb
• Related: 1EHO 1EHQ 1KCJ 1P0I 1P0M 1P0P 1P0Q 1XLU 1XLV 1XLW 2J4C 2WID 2WIF 2WIG 2WIJ 2WIK 2WIL 2WSL 2XMB 2XMC 2XMD
• Descriptor: CHOLINESTERASE, 2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-[beta-L-fucopyranose-(1-6)]2-acetamido-2-deoxy-beta-D-glucopyranose, beta-L-fucopyranose-(1-6)-2-acetamido-2-deoxy-beta-D-glucopyranose, ... (10 entities in total)
• Functional Keywords: glycoprotein, hydrolase
• Biological source: HOMO SAPIENS (HUMAN)
• Total number of polymer chains: 1
• Total formula weight: 62400.14

Authors

Nachon, F.,Carletti, E.,Wandhammer, M.,Nicolet, Y.,Schopfer, L.M.,Masson, P.,Lockridge, O. (deposition date: 2010-07-27, release date: 2010-12-01, Last modification date: 2024-11-13)

Primary citation

Nachon, F.,Carletti, E.,Wandhammer, M.,Nicolet, Y.,Schopfer, L.M.,Masson, P.,Lockridge, O.
X-Ray Crystallographic Snapshots of Reaction Intermediates in the G117H Mutant of Human Butyrylcholinesterase, a Nerve Agent Target Engineered Into a Catalytic Bioscavenge
Biochem.J., 434:73-, 2011

PubMed Abstract: OPs (organophosphylates) exert their acute toxicity through inhibition of acetylcholinesterase, by phosphylation of the catalytic serine residue. Engineering of human butyrylcholinesterase, by substitution of a histidine residue for the glycine residue at position 117, led to the creation of OP hydrolase activity. However, the lack of structural information and poor understanding of the hydrolytic mechanism of the G117H mutant has hampered further improvements in the catalytic activity. We have solved the crystallographic structure of the G117H mutant with a variety of ligands in its active site. A sulfate anion bound to the active site suggested the positioning for an OP prior to phosphylation. A fluoride anion was found in the active site when NaF was added to the crystallization buffer. In the fluoride complex, the imidazole ring from the His117 residue was substantially shifted, adopting a relaxed conformation probably close to that of the unliganded mutant enzyme. Additional X-ray structures were obtained from the transient covalent adducts formed upon reaction of the G117H mutant with the OPs echothiophate and VX [ethyl ({2-[bis(propan-2-yl)amino]ethyl}sulfanyl](methyl)phosphinate]. The position of the His117 residue shifted in response to the introduction of these adducts, overlaying the phosphylserine residue. These structural data suggest that the dephosphylation mechanism involves either a substantial conformational change of the His117 residue or an adjacent nucleophilic substitution by water.

PubMed: 21091433
DOI: 10.1042/BJ20101648

Experimental method

X-RAY DIFFRACTION (2.7 Å)