DDT-dehydrochlorinase

 

This glutathione reductase is known to perform the conjugation of reduced glutathione to a wide number of exogenous and endogenous hydrophobic electrophiles [PMID:22082028, PMID:20417639]. Has DDT dehydrochlorinase activity [PMID:20417639] and may also be involved in detoxification [PMID:22082028]. Docking and NMR studies have shown that the DDT molecule binds in the H-site.

 

Reference Protein and Structure

Sequence
P20432 UniProt (2.5.1.18, 4.5.1.1) IPR004045 (Sequence Homologues) (PDB Homologues)
Biological species
Drosophila melanogaster (Fruit fly) Uniprot
PDB
3mak - Crystal structure of Glutathione transferase dmGSTD1 from Drosophila melanogaster, in complex with glutathione (1.8 Å) PDBe PDBsum 3mak
Catalytic CATH Domains
3.40.30.10 CATHdb (see all for 3mak)
Cofactors
Glutathione (1)
Click To Show Structure

Enzyme Reaction (EC:4.5.1.1)

DDT
CHEBI:16130ChEBI
→
DDE
CHEBI:16598ChEBI
+
chloride
CHEBI:17996ChEBI
+
hydron
CHEBI:15378ChEBI
Alternative enzyme names: DDT-ase, 1,1,1-trichloro-2,2-bis(4-chlorophenyl)ethane chloride-lyase, DDTase,

Enzyme Mechanism

Introduction

The thiolate group of activated ionic GSH abstracts the DDT beta-hydrogen, which eliminates a chloride ion from DDT to yield the final product DDE. The chloride anion then abstracts the proton from GSH to regenerate the enzyme active site.

Catalytic Residues Roles

UniProt PDB* (3mak)
Ser10 Ser10A Stabilises the thiolate anion of glutathione. electrostatic stabiliser
*PDB label guide - RESx(y)B(C) - RES: Residue Name; x: Residue ID in PDB file; y: Residue ID in PDB sequence if different from PDB file; B: PDB Chain; C: Biological Assembly Chain if different from PDB. If label is "Not Found" it means this residue is not found in the reference PDB.

Chemical Components

proton transfer, bimolecular elimination, overall reactant used, overall product formed, native state of enzyme regenerated, native state of cofactor regenerated

References

  1. Wang Y et al. (2008), J Struct Biol, 164, 228-235. Structure of an insect epsilon class glutathione S-transferase from the malaria vector Anopheles gambiae provides an explanation for the high DDT-detoxifying activity. DOI:10.1016/j.jsb.2008.08.003. PMID:18778777.
  2. Saisawang C et al. (2012), Biochem J, 442, 181-190. A preliminary characterization of the cytosolic glutathione transferase proteome from Drosophila melanogaster. DOI:10.1042/BJ20111747. PMID:22082028.
  3. Wongsantichon J et al. (2012), Arch Biochem Biophys, 521, 77-83. Structural evidence for conformational changes of Delta class glutathione transferases after ligand binding. DOI:10.1016/j.abb.2012.03.023. PMID:22475449.
  4. Ayres CF et al. (2011), PLoS One, 6, e29237-. Comparative genomics of the anopheline glutathione S-transferase epsilon cluster. DOI:10.1371/journal.pone.0029237. PMID:22206003.
  5. Low WY et al. (2010), J Mol Biol, 399, 358-366. Recognition and detoxification of the insecticide DDT by Drosophila melanogaster glutathione S-transferase D1. DOI:10.1016/j.jmb.2010.04.020. PMID:20417639.
  6. Chen L et al. (2003), Acta Crystallogr D Biol Crystallogr, 59, 2211-2217. Structure of an insect delta-class glutathione S-transferase from a DDT-resistant strain of the malaria vector Anopheles gambiae. PMID:14646079.

Step 1. Activated glutathione abstracts the beta proton from the DDT substrate.

Download: Image, Marvin File

Catalytic Residues Roles

Residue Roles
Ser10A electrostatic stabiliser

Chemical Components

proton transfer, ingold: bimolecular elimination, overall reactant used, overall product formed

Step 2. In an inferred return step the activated glutathione species is regenerated. The species responsible for the final proton abstraction is not known, shown here as the product chloride anion.

Download: Image, Marvin File

Catalytic Residues Roles

Residue Roles
Ser10A electrostatic stabiliser

Chemical Components

native state of enzyme regenerated, proton transfer, overall product formed, native state of cofactor regenerated
Download: Image, Marvin File

Step 1. Activated glutathione abstracts the beta proton from the DDT substrate.

Step 2. In an inferred return step the activated glutathione species is regenerated. The species responsible for the final proton abstraction is not known, shown here as the product chloride anion.

Products.

Contributors

Gemma L. Holliday