title: Cloning, characterization and regulation of a family of phi class glutathione transferases from wheat.
abstract: Six phi (F) class glutathione transferases (GSTs) were cloned from bread wheat (Triticum aestivum L.) treated with the herbicide safener fenchlorazole ethyl and named TaGSTF1-6. Recombinant TaGSTFs were assayed for glutathione conjugating activity towards xenobiotics including herbicides and for glutathione peroxidase (GPOX) activity. TaGSTF1, which resembled ZmGSTF1, the dominant GST in maize (Zea mays), was highly active in conjugating 1-chloro-2,4-dinitrobenezene (CDNB) but had low activities towards chloroacetanilide, diphenyl ether and aryloxphenoxypropionate herbicides. TaGSTF2, TaGSTF3 and TaGSTF4 all resembled the safener-inducible ZmGSTF2, with TaGSTF2 and TaGSTF3 being highly active GPOXs and rapidly detoxifying chloroacetanilides. TaGSTF5 resembled ZmGSTF3, having limited conjugating and GPOX activity. TaGSTF6 contained both ZmGSTF1- and ZmGSTF2-like sequences but was most similar to ZmGSTF1 in detoxifying activity. The expression of TaGSTFs in wheat seedlings was enhanced upon exposure to fenchlorazole ethyl, herbicides or other chemical inducing treatments. TaGSTFs were also enhanced by treatment with the natural products caffeic acid, 7,4-dihydroxyflavone and naringenin. The CDNB-conjugating activity of TaGSTF1, and to a lesser extent TaGSTF6, was highly sensitive to inhibition by flavonoids, particularly the chalcone isoliquiritigenin. The other TaGSTFs were much less sensitive to such inhibition. It was subsequently determined that isoliquiritigenin underwent glutathione conjugation, though this reversible reaction did not require the intervention of any TaGSTF. The potential importance of GSTFs and glutathione conjugation in flavonoid metabolism is discussed.
authors.affiliation: Crop Protection Group, School of Biological and Biomedical Sciences, University of Durham, Durham, DH1 3LE, UK.
authors.forename: Ian
authors.initials: I
authors.lastname: Cummins
authors.forename: David
authors.initials: D
authors.lastname: O'Hagan
authors.forename: Istvan
authors.initials: I
authors.lastname: Jablonkai
authors.forename: David J
authors.initials: DJ
authors.lastname: Cole
authors.forename: Alain
authors.initials: A
authors.lastname: Hehn
authors.forename: Danièle
authors.initials: D
authors.lastname: Werck-Reichhart
authors.forename: Robert
authors.initials: R
authors.lastname: Edwards
mesh_terms: D000595:Amino Acid Sequence; D003001:Cloning, Molecular; D005419:Flavonoids / Q000378:metabolism / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D005978:Glutathione / Q000378:metabolism / Q000494:pharmacology; D005982:Glutathione Transferase / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D006540:Herbicides / Q000494:pharmacology; D015151:Immunoblotting; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D011994:Recombinant Proteins / Q000187:drug effects / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014908:Triticum / Q000187:drug effects / Q000201:enzymology / Q000235:genetics*; D015262:Xenobiotics / Q000494:pharmacology
chemical_list: D005419:Flavonoids; D006540:Herbicides; D007527:Isoenzymes; D011994:Recombinant Proteins; D015262:Xenobiotics; D005982:Glutathione Transferase; D005978:Glutathione