Reference "Purification, regulation and cloning of a glutathione transferase (GST) from maize resembling the auxin-inducible type-III GSTs"

Reference ID

7470

Title

Purification, regulation and cloning of a glutathione transferase (GST) from maize resembling the auxin-inducible type-III GSTs

Source

Plant molecular biology, 1998, vol. 36, pp. 75-87

Authors (3)

Dixon-D-P	Cole-D-J
Edwards-R

Abstract

The glutathione transferases (GSTs) from maize (Zea mays L.) with activities
toward the chloroacetanilide herbicide metolachlor and the diphenyl ether
herbicide fluorodifen were fractionated into two pools based on binding to
affinity columns. Pool 1 GSTs were retained on Orange A agarose and were
identified as isoenzymes Zea mays (Zm) GST I-I, Zm GST I-II and Zm GST I-III,
which have been described previously. Pool 2 GSTs selectively bound to S-hexyl-glutathione-
Sepharose and were distinct from the pool 1 GSTs, being composed of a homodimer
of 28.5 kDa subunits, termed Zm GST V-V, and a heterodimer of the 28.5 kDa
polypeptide and a 27.5 kDa subunit, termed Zm GST V-VI. Using an antibody raised
to Zm GST V-VI, a cDNA expression library was screened and a Zm GST V clone
identified showing sequence similarity to the type-III auxin-inducible GSTs
previously identified in tobacco and other dicotyledenous species. Recombinant
Zm GST V-V showed high GST activity towards the diphenyl ether herbicide
fluorodifen, detoxified toxic alkenal derivatives and reduced organic
hydroperoxides. Antibodies raised to Zm GST I-II and Zm GST V-VI were used to
monitor the expression of GST subunits in maize seedlings. Over a 24 h period
the Zm GST I subunit was unresponsive to chemical treatment, while expression of
Zm GST II was enhanced by auxins, herbicides, the herbicide safener dichlormid
and glutathione. The Zm GST V subunit was more selective in its induction, only
accumulating significantly in response to dichlormid treatment. During
development Zm GST I and Zm GST V were expressed more in roots than in shoots,
with Zm GST II expression limited to the roots.