PDBsum entry: 1lzl

Hydrolase

PDB id: 1lzl

Contents

Protein chain

317 a.a. *

Waters ×313

* Residue conservation analysis

PDB id:

1lzl

Name:

Hydrolase

Title:

Bacterial heroin esterase

Structure:

Heroin esterase. Chain: a. Engineered: yes

Source:

Rhodococcus sp.. Organism_taxid: 1831. Strain: h1. Expressed in: escherichia coli. Expression_system_taxid: 562.

Biol. unit:

Dimer (from PQS)

Resolution:

1.30Å R-factor: 0.153 R-free: 0.213

Authors:

X.Zhu,N.A.Larsen,A.Basran,N.C.Bruce,I.A.Wilson

Key ref:

X.Zhu et al. (2003). Observation of an arsenic adduct in an acetyl esterase crystal structure. J Biol Chem, 278, 2008-2014. PubMed id: 12421810 DOI: 10.1074/jbc.M210103200

Date:

10-Jun-02 Release date: 28-Jan-03

Protein chain

O06441  (O06441_RHOSO) -  Heroin esterase

Seq: 322 a.a.

Struc: 317 a.a.*

* PDB and UniProt seqs differ at 14 residue positions (black crosses)

DOI no: 10.1074/jbc.M210103200

J Biol Chem 278:2008-2014 (2003)

PubMed id: 12421810

Observation of an arsenic adduct in an acetyl esterase crystal structure.

X.Zhu, N.A.Larsen, A.Basran, N.C.Bruce, I.A.Wilson.

ABSTRACT

The crystal structures of an acetyl esterase, HerE, and its complex with an inhibitor dimethylarsinic acid have been determined at 1.30- and 1.45-A resolution, respectively. Although the natural substrate for the enzyme is unknown, HerE hydrolyzes the acetyl groups from heroin to yield morphine and from phenyl acetate to yield phenol. Recently, the activity of the enzyme toward heroin has been exploited to develop a heroin biosensor, which affords higher sensitivity than other currently available detection methods. The crystal structure reveals a single domain with the canonical alpha/beta hydrolase fold with an acyl binding pocket that snugly accommodates the acetyl substituent of the substrate and three backbone amides that form a tripartite oxyanion hole. In addition, a covalent adduct was observed between the active site serine and dimethylarsinic acid, which inhibits the enzyme. This crystal structure provides the first example of an As-containing compound in a serine esterase active site and the first example of covalent modification of serine by arsenic. Thus, the HerE complex reveals the structural basis for the broad scope inhibition of serine hydrolases by As(V)-containing organic compounds.

Selected figure(s)

Figure 3.
Fig. 3. HerE forms a dimer. In this view, the two molecules are rendered in light and dark shades and are related by a 2-fold crystallographic axis that is perpendicular to the plane of the paper. The interface is formed by continuation of the central -sheet via four hydrogen bonds between strands 8. In addition, there are coiled-coil interactions between helices E-E and F'-F'.

Figure 6.
Fig. 6. Proposed mechanism for arsenic inhibitor binding. His-290 acts as a general acid and general base. In the first step, His-290 deprotonates the Ser-160 hydroxyl, facilitating nucleophilic attack of arsenic by the reactive serine O . This attack results in the formation of a transient trigonal bipyramidal transition state, where the oxyanion is stabilized by three hydrogen bonds in the oxyanion hole, and the hydroxyl forms a hydrogen bond with His-290. His-290 then acts as a general acid, protonating the hydroxyl leaving group. In the final tetrahedral complex, the oxygen is divalent and remains positioned in the oxyanion hole. The pro-S methyl group interacts with Trp-209 in the acyl binding pocket, and the pro-R methyl forms close van der Waals contacts with the histidine.

The above figures are reprinted by permission from the ASBMB: J Biol Chem (2003, 278, 2008-2014) copyright 2003.

Figures were selected by an automated process.