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School of Biological and Biomedical Sciences

Academic Staff

Publication details for Prof Robert Edwards

Dixon, DP, Cole, DJ & Edwards, R (2000). Characterisation of a zeta class glutathione transferase from Arabidopsis thaliana with a putative role in tyrosine catabolism. Archives Of Biochemistry And Biophysics 384(2): 407-412.
  • Publication type: Journal papers: academic
  • ISSN/ISBN: 0003-9861
  • Keywords: Arabidopsis thaliana; glutathione; glutathione transferase; isomerase;tyrosine degradationS-TRANSFERASES; MALEYLACETOACETATE ISOMERASE; GENE; HOMOGENTISATE;DIOXYGENASE; ACID; IDENTIFICATION; PURIFICATION; BIOSYNTHESIS;INHIBITION
  • View online: Online version

Author(s) from Durham

Abstract

A glutathione transferase (GST) similar to zeta GSTs in animals and
fungi has been cloned from Arabidopsis thaliana using RT-PCR. The
Arabidopsis zeta GST (AtGSTZ1) was expressed in Escherichia coli as
his-tagged polypeptides, which associated together to form the 50-kDa
AtGSTZ1-1 homodimer. Following purification, AtGSTZ1-1 was assayed for
a range of activities and compared with other purified recombinant
plant GSTs from the phi, tau, and theta classes. AtGSTZ1-1 differed
from the other GSTs in showing no glutathione conjugating activity
toward xenobiotics and no glutathione peroxidase activity toward
organic hydroperoxides. Uniquely among the plant GSTs, AtGSTZ1-1 showed
activity as a maleylacetone isomerase (MAI). This glutathione-dependent
reaction is analogous to the cis-trans isomerization of
maleylacetoacetate to fumarylacetoacetate, which occurs in the course
of tyrosine catabolism to acetoacetate and fumarate. Thus, rather than
functioning as a conventional GST, AtGSTZ1-1 appears to be involved in
tyrosine degradation. In addition to the MAI activity, the AtGSTZ1-1
also catalyzed the glutathione-dependent dehalogenation of
dichloroacetic acid to glyoxylic acid. This latter activity was used to
demonstrate the presence of functional AtGSTZ1-1 in planta. (C) 2000
Academic Press.