Glutathione reductase turned into trypanothione reductase: structural analysis of an engineered change in substrate specificity.Stoll, V.S., Simpson, S.J., Krauth-Siegel, R.L., Walsh, C.T., Pai, E.F.
(1997) Biochemistry 36: 6437-6447
- PubMed: 9174360
- DOI: 10.1021/bi963074p
- Primary Citation of Related Structures:
- PubMed Abstract:
- Comparison of the Three-Dimensional Protein and Nucleotide Structure of the Fad-Binding Domain of P-Hydroxybenzoate Hydroxylase with the Fad-as Well as Nadph-Binding Domains of Glutathione Reductase
Wierenga, R.K.,Drenth, J.,Schulz, G.E.
(1983) J.Mol.Biol. 167: 725
- Fad-Binding Site of Glutathione Reductase
Schulz, G.E.,Schirmer, R.H.,Pai, E.F.
(1982) J.Mol.Biol. 160: 287
- Three-Dimensional Structure of Glutathione Reductase at 2 A Resolution
Thieme, R.,Pai, E.F.,Schirmer, R.H.,Schulz, G.E.
(1981) J.Mol.Biol. 152: 763
- The Structure of the Flavoenzyme Glutathione Reductase
Schulz, G.E.,Schirmer, R.H.,Sachsenheimer, W.,Pai, E.F.
(1978) Nature 273: 120
- Refined Structure of Glutathione Reductase at 1.54 A Resolution
Karplus, P.A.,Schulz, G.E.
(1987) J.Mol.Biol. 195: 701
- Low Resolution Structure of Human Erythrocyte Glutathione Reductase
Zappe, H.A.,Krohne-Ehrich, G.,Schulz, G.E.
(1977) J.Mol.Biol. 113: 141
- Crystals of Human Erythrocyte Glutathione Reductase
Schulz, G.E.,Zappe, H.,Worthington, D.J.,Rosemeyer, M.A.
(1975) FEBS Lett. 54: 86
- Glutathione Reductase from Human Erythrocytes. The Sequences of the Nadph Domain and of the Interface Domain
Krauth-Siegel, R.L.,Blatterspiel, R.,Saleh, M.,Schiltz, E.,Schirmer, R.H.,Untucht-Grau, R.
(1982) Eur.J.Biochem. 121: 259
- The Catalytic Mechanism of Glutathione Reductase as Derived from X-Ray Diffraction Analyses of Reaction Intermediates
Pai, E.F.,Schulz, G.E.
(1983) J.Biol.Chem. 258: 1752
- The C-Terminal Fragment of Human Glutathione Reductase Contains the Postulated Catalytic Histidine
Untucht-Grau, R.,Schulz, G.E.,Schirmer, R.H.
(1979) FEBS Lett. 105: 244
- Gene Duplication in Glutathione Reductase
(1980) J.Mol.Biol. 138: 335
- Redox Enzyme Engineering: Conversion of Human Glutathione Reductase Into a Trypanothione Reductase
Bradley, M.,Bucheler, U.S.,Walsh, C.T.
(1991) Biochemistry 30: 6124
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 ...
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.
Department of Biochemistry, University of Toronto, Ontario Cancer Institute, Canada.