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Plant glutathione transferases functioning as ligandins

Reference	BB/C51227X/1
Principal Investigator / Supervisor	Professor Robert Edwards
Co-Investigators / Co-Supervisors	Dr David Dixon, Dr Adrian Lapthorn
Institution	Durham University
Department	Biological and Biomedical Sciences
Funding type	Research
Value (£)	325,305
Status	Completed
Type	Research Grant
Start date	01/04/2005
End date	31/03/2008
Duration	36 months

Abstract

Arabidopsis thaliana (at) contains 26 tau (U) class glutathione transferases (GSTs) and 15 phi (F) GSTs, most of which have no assigned function. We have recently determined that the expression of maize GSTUs in Arabidopsis gives rise to a selective depletion in porphyrins and a major upregulation of phenolic metabolism under conditions of imposed abiotic stress. Based on this disruption and the activity of the GSTUs in vitro we propose that the ectopic expression of these proteins has interfered with the shuttling of porphyrins between the chloroplast and organelles, thereby unmasking a similar function for AtGSTU and AtGSTF orthologues. We also propose that specific ligandins function in light-mediated signalling cascades by acting as carriers of photoactive porphyrins and that this can regulate the central pathways of phenylpropanoid and flavonoid metabolism. In a three year interdisciplinary programme with structural biologists at Glasgow, we propose to define the conditions under which the transgenic ligandins function, determine the structural basis of porphyrin binding and identify AtGST orthologues. The AtGST ligandins will be characterised for binding activities in vitro and their roles in regulating porphyrin and phenolic metabolism determined in Arabidopsis using a combination of analysis of mutants and transgenic manipulation of ligandin expression. Finally the mechanism by which ligandins up-regulate phenylpropanoid and flavonoid accumulation will be determined. Technical objectives of the grant are: Objective 1. Define the effects of transgenic expression of ZmGSTUs, on porphyrin and phenolic metabolism (0 to 6 months; Durham). Objective 2. Structural characterisation of porphyrin binding to GST ligandins (Glasgow, 0-36 months). Objective 3. Identifying and characterising AtGSTs with ligandin activity (6 to 18 months; Durham). Objective 4. Effect of disrupting AtGST ligandin expression on phenolic and porphyrin metabolism in planta (0 to 30 months, Durham). Objective 5. Mechanisms of regulation of phenolic metabolism by AtGST ligandins (30 to 36 months; Durham).

Summary

unavailable

Committee	Closed Committee - Plant & Microbial Sciences (PMS)
Research Topics	X – not assigned to a current Research Topic
Research Priority	X – Research Priority information not available
Research Initiative	X - not in an Initiative
Funding Scheme	X – not Funded via a specific Funding Scheme

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