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A 2,4‐D‐inducible glutathione S‐transferase from soybean ( Glycine max ). Purification, characterisation and induction
Author(s) -
Flury Thomas,
Adam Daniel,
Kreuz Klaus
Publication year - 1995
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1995.tb05317.x
Subject(s) - auxin , glutathione s transferase , biochemistry , glutathione , isozyme , affinity chromatography , molecular mass , glycine , 2,4 dichlorophenoxyacetic acid , amino acid , chemistry , polar auxin transport , protein subunit , enzyme , biology , microbiology and biotechnology , arabidopsis , gene , botany , mutant
Glutathione S‐transferases (GSTs; EC 2.5.1.18) have recently been proposed to form one large group among the auxin‐induced proteins. However. the properties and regulation of such auxin‐responsive GSTs in the plant still await detailed investigation. In this study, a 2,4‐dichloro‐phenoxyacetic acid (2,4‐D)‐inducible GST isozyme from soybean ( Glycine max [L.] Merr. cv. Williams) was purified to near homogeneity by anion‐exchange and affinity chromatography on S‐hexylglutathione agarose. The native enzyme had a molecular mass of 49 kDa, as determined by gel filtration, and consisted of 26‐kDa subunits. The purified GST conjugated glutathione to 1‐chloro‐2,4‐dinitrobenzene and to the herbicide metolachlor, but not to the other GST substrates atrazine. fluorodifen or trans‐cinnamic acid. The N‐termmal amino acid sequence shared significant homology with the deduced polypeptide sequences of two 2,4‐D‐inducible genes from tobacco, par A and CNT107 . The levels of the 26‐kDa GST subunit protein in soybean hypocotyls were analysed by immunoblotting. At micromolar concentrations, 2,4‐D induced a transient increase in net accumulation of GST, whereas indole‐3‐acetic acid or I‐naphthaleneacetic acid did not increase the GST levels. Known inhibitors of polar auxin transport, including 2.3.5‐tri‐iodobenzoic acid. N‐I‐naphthylphthalamic acid and analogues thereof, differed widely in their ability to elicit GST protein accumulation. It is concluded that the induction of soybean GST by 2,4‐D and by some of the auxin transport inhibitors is not related to auxin activity or to changes in the endogenous auxin levels.