title: Structure of a tau class glutathione S-transferase from wheat active in herbicide detoxification.
abstract: Glutathione S-transferases (GSTs) from the phi (GSTF) and tau (GSTU) classes are unique to plants and play important roles in stress tolerance and secondary metabolism as well as catalyzing the detoxification of herbicides in crops and weeds. We have cloned and functionally characterized a group of GSTUs from wheat treated with fenchlorazole-ethyl, a herbicide safener. One of these enzymes, TaGSTU4-4, was highly active in conjugating the chemically distinct wheat herbicides fenoxaprop and dimethenamid. The structure of TaGSTU4-4 has been determined at 2.2 A resolution in complex with S-hexylglutathione. This enzyme is the first tau class GST structure to be determined and most closely resembles the omega class GSTs, but without the unique N-terminal extension or active site cysteine. The X-ray structure identifies key amino acid residues in the hydrophobic binding site and provides insights into the substrate specificity of these enzymes.
authors.affiliation: Department of Chemistry, University of Glasgow, Glasgow, G12 8QQ, United Kingdom.
authors.forename: Russell
authors.initials: R
authors.lastname: Thom
authors.forename: Ian
authors.initials: I
authors.lastname: Cummins
authors.forename: David P
authors.initials: DP
authors.lastname: Dixon
authors.forename: Robert
authors.initials: R
authors.lastname: Edwards
authors.forename: David J
authors.initials: DJ
authors.lastname: Cole
authors.forename: Adrian J
authors.initials: AJ
authors.lastname: Lapthorn
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D003001:Cloning, Molecular; D019281:Dimerization; D005978:Glutathione / Q000378:metabolism*; D005982:Glutathione Transferase / Q000737:chemistry* / Q000378:metabolism; D006540:Herbicides / Q000378:metabolism*; D008658:Inactivation, Metabolic / Q000502:physiology; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity; D014908:Triticum / Q000201:enzymology*
chemical_list: D006540:Herbicides; D011994:Recombinant Proteins; D005982:Glutathione Transferase; D005978:Glutathione