Dixon, D. P. and Sellars, J. D. and Edwards, R. (2011) 'The 'Arabidopsis' phi class glutathione transferase 'At'GSTF2 : binding and regulation by biologically active heterocyclic ligands.', Biochemical journal., 438 (1). pp. 63-70.
The plant-specific phi class of glutathione transferases (GSTFs) are often highly stress-inducible and expressed in a tissue-specific manner, suggestive of them having important protective roles. To date, these functions remain largely unknown, although activities associated with the binding and transport of reactive metabolites have been proposed. Using a sensitive and selective binding screen, we have probed the Arabidopsis thaliana GSTFs for natural product ligands from bacteria and plants. Uniquely, when over-expressed in bacteria, family members GSTF2 and GSTF3 bound a series of heterocyclic compounds including lumichrome, harmane, norharmane and indole-3-aldehyde. When screened against total metabolite extracts from A. thaliana, GSTF2 also selectively bound the indole-derived phytoalexin camalexin as well as the flavonol quercetin-3-O-rhamnoside. In each case, isothermal titration calorimetry revealed high affinity binding (typically Kd < 1 µM), which was enhanced in the presence of glutathione and by the other heterocyclic ligands. With GSTF2, these secondary ligand associations resulted in an allosteric enhancement in glutathione conjugating activity. Together with the known stress responsiveness of GSTF2 and its association with membrane vesicles, these results are suggestive of roles in regulating the binding and transport of defence-related compounds in planta.
|Keywords:||Flavonoid, Indole, Ligandin, Phi class glutathione transferase 2 (GSTF2), Phytoalexin, Plant defence.|
|Full text:||PDF - Accepted Version (179Kb)|
|Publisher Web site:||http://dx.doi.org/10.1042/BJ20101884|
|Publisher statement:||The Version of Record (VoR) is available at www.biochemj.org|
|Record Created:||02 Aug 2011 17:20|
|Last Modified:||20 Jun 2012 15:27|
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