The Structure of a Zeta Class Glutathione S-Transferase from Arabidopsis Thaliana: Characterisation of a Gst with Novel Active-Site Architecture and a Putative Role in Tyrosine Catabolism.Thom, R., Dixon, D.P., Edwards, R., Cole, D.J., Lapthorn, A.J.
(2001) J.Mol.Biol. 308: 949
- PubMed: 11352584
- DOI: 10.1006/jmbi.2001.4638
- PubMed Abstract:
- Characterisation of a Zeta Class Glutathione Transferase from Arabidopsis Thaliana with a Putative Role in Tyrosine Catabolism
Dixon, D.P.,Cole, D.J.,Edwards, R.
(2000) Arch.Biochem.Biophys. 384: 407
The cis-trans isomerisation of maleylacetoacetate to fumarylacetoacetate is the penultimate step in the tyrosine/phenylalanine catabolic pathway and has recently been shown to be catalysed by glutathione S-transferase enzymes belonging to the zeta cl ...
The cis-trans isomerisation of maleylacetoacetate to fumarylacetoacetate is the penultimate step in the tyrosine/phenylalanine catabolic pathway and has recently been shown to be catalysed by glutathione S-transferase enzymes belonging to the zeta class. Given this primary metabolic role it is unsurprising that zeta class glutathione S-transferases are well conserved over a considerable period of evolution, being found in vertebrates, plants, insects and fungi. The structure of this glutathione S-transferase, cloned from Arabidopsis thaliana, has been solved by single isomorphous replacement with anomalous scattering and refined to a final crystallographic R-factor of 19.6% using data from 25.0 A to 1.65 A. The zeta class enzyme adopts the canonical glutathione S-transferase fold and forms a homodimer with each subunit consisting of 221 residues. In agreement with structures of glutathione S-transferases from the theta and phi classes, a serine residue (Ser17) is present in the active site, at a position that would allow it to stabilise the thiolate anion of glutathione. Site-directed mutagenesis of this residue confirms its importance in catalysis. In addition, the role of a highly conserved cysteine residue (Cys19) present in the active site of the zeta class glutathione S-transferase enzymes is discussed.
Department of Chemistry, University of Glasgow, Glasgow, G12 8QQ, UK.