PDBsum entry: 3grt

Oxidoreductase

PDB id: 3grt

Contents

Protein chain

461 a.a. *

Ligands

FAD

TS2

Waters ×3

* Residue conservation analysis

PDB id:

3grt

Name:

Oxidoreductase

Title:

Human glutathione reductase a34e, r37w mutant, oxidized tryp complex

Structure:

Glutathione reductase. Chain: a. Synonym: grtr. Engineered: yes. Mutation: yes. Other_details: contains a non-covalently bound fad and oxid glutathione substrate

Source:

Homo sapiens. Human. Organism_taxid: 9606. Organ: blood. Cell: red blood cells. Expressed in: escherichia coli. Expression_system_taxid: 562.

Biol. unit:

Dimer (from PQS)

Resolution:

2.50Å R-factor: 0.171

Authors:

V.S.Stoll,S.J.Simpson,R.L.Krauth-Siegel,C.T.Walsh,E.F.Pai

Key ref:

V.S.Stoll et al. (1997). Glutathione reductase turned into trypanothione reductase: structural analysis of an engineered change in substrate specificity. Biochemistry, 36, 6437-6447. PubMed id: 9174360 DOI: 10.1021/bi963074p

Date:

12-Feb-97 Release date: 12-Aug-97

Protein chain

P00390  (GSHR_HUMAN) -  Glutathione reductase, mitochondrial

Seq: 522 a.a.

Struc: 461 a.a.*

* PDB and UniProt seqs differ at 2 residue positions (black crosses)

Enzyme reactions

• Enzyme class: E.C.1.8.1.7 - Glutathione-disulfide reductase.
• Reaction: 2 glutathione + NADP⁺ = glutathione disulfide + NADPH

2 × glutathione + NADP(+) = glutathione disulfide (Bound ligand (Het Group name = TS2) matches with 76.00% similarity) + NADPH

• Cofactor: FAD

FAD (Bound ligand (Het Group name = FAD) corresponds exactly)

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

 Gene Ontology (GO) functional annotation 

• Cellular component: cytoplasm (1 term)
• Biological process: oxidation-reduction process (3 terms)
• Biochemical function: oxidoreductase activity (5 terms)

reference

DOI no: 10.1021/bi963074p

Biochemistry 36:6437-6447 (1997)

PubMed id: 9174360

Glutathione reductase turned into trypanothione reductase: structural analysis of an engineered change in substrate specificity.

V.S.Stoll, S.J.Simpson, R.L.Krauth-Siegel, C.T.Walsh, E.F.Pai.

ABSTRACT

Trypanosoma and Leishmania, pathogens responsible for diseases such as African sleeping sickness, Chagas' heart disease, or Oriental sore, are two of the very few genera that do not use the ubiquitous glutathione/glutathione reductase system to keep a stable cellular redox balance. Instead, they rely on trypanothione and trypanothione reductase to protect them from oxidative stress. Trypanothione reductase (TR) and the corresponding host enzyme, human red blood cell glutathione reductase (GR), belong to the same flavoprotein family. Despite their closely related three-dimensional structures and although their natural substrates share the common structural glutathione core, the two enzymes are mutually exclusive with respect to their disulfide substrates. This makes the parasite enzyme a potential target for antitrypanosomal drug design. While a large body of structural data on GR complexes is available, information on TR-ligand interactions is very limited. When the two amino acid changes Ala34Glu and Arg37Trp are introduced into human GR, the resulting mutant enzyme (GRTR) prefers trypanothione 700-fold over its original substrate, effectively converting a GR into a TR [Bradley, M., Bücheler, U. S., & Walsh, C. T. (1991) Biochemistry 30, 6124-6127]. The crystal structure of GRTR has been determined at 2.3 A resolution and refined to a crystallographic R factor of 20.9%. We have taken advantage of the ease with which ligand complexes can be produced in GR crystals, a property that extends to the isomorphous GRTR crystals, and have produced and analyzed crystals of GRTR complexes with glutathione, trypanothione, glutathionylspermidine and of a true catalytic intermediate, the mixed disulfide between trypanothione and the enzyme. The corresponding molecular structures have been characterized at resolutions between 2.3 and 2.8 A with R factors ranging from 17.1 to 19.7%. The results indicate that the Ala34Glu mutation causes steric hindrance leading to a large displacement of the side chain of Arg347. This movement combined with the change in charge introduced by the mutations modifies the binding cavity, forcing glutathione to adopt a nonproductive binding mode and permitting trypanothione and to a certain degree also the weak substrate glutathionylspermidine to assume a productive mode.