A glutathione S‐transferase with glutathione‐peroxidase activity from Arabidopsis thaliana

Abstract

A full-length cDNA clone for a novel glutathione S-transferase was isolated from Arabidopsis thaliana and characterized. The cDNA encodes a polypeptide of 218 amino acids with a calculated molecular mass of 24363 Da. The sequence was most related to the theta class within the glutathione-S-transferase superfamily of enzymes. The protein encoded by the cDNA was functionally expressed and enzymically active in Escherichia coli ; glutathione-S-transferase activity with the standard enzyme substrate 1 -chloro-2,4-dinitrobenzene was demonstrated (apparent K,, 10 mM ; apparent K,, for glutathione, 0.08 mM). The enzyme is substrate specific and did not use several electrophilic reduced-glutathione acceptor molecules for conjugation. However, it efficiently catalyzed the conversion of 13-hydroperoxy-9,11,15-octadecatrienoic acid (Km, 0.67 mM) as well as 13-hydroperoxy-9,ll -0ctadecadienoic acid (K,,, 0.79 mM) to the corresponding hydroxy derivatives with concomitant formation of oxidized glutathione. The enzyme did not use H,O, as substrate. Thus, the cloned A. thaliana enzyme functions as glutathione peroxidase and, in the plant cell, may be involved in the removal of reactive organic hydroperoxides, such as the products of lipid peroxidation. The enzyme is structurally and enzymically, however, unrelated to the selenium-containing glutathione peroxidases. Enzymic and immunoblotting data suggest that the A. thaliana enzyme is soluble and constitutively expressed in vegetative rosettes, but is under developmental control during the transition to bolting and flowering.

Isolation and characterization of an auxin-inducible glutathione S-transferase gene of Arabidopsis thaliana

“…Also proteins encoded by different GSTs of arabidopsis were compared to the AT103-1A protein. These protein sequences were dervived from cDNAs or genes gst2 [20], PM239x14 [1], E R D l l and ERD13 [11]. tains two exons interrupted by one intron.…”

S-glutathionylation: relevance in diabetes and potential role as a biomarker

“…They catalyze the formation of adducts of glutathione with electrophilic compounds that are exported out of the cell (Coleman et al, 1997) (Figure 1, reaction 7). They can also act as peroxidases and thiol transferases (Bartling et al, 1993;Board et al, 2000). Human GSTs are divided into two groups: microsomal and cytosolic.…”

Photosynthetic electron transport regulates the expression of cytosolic ascorbate peroxidase genes in Arabidopsis during excess light stress.

“…The following were used in this study: Fe-, Mn-and CuZn-SOD cDNAs from Scots pine and Nicotiana plumbaginafiolia (Bowler et al, 1989;Van Camp et al, 1990;Karpinski et al, 1992); cytosolic GOR2 and organellar GOR7 from pea (Creissen et al, 1992; EMBL accession number X98274); CAT7 and CAT2 from tobacco (Willekens et al, 1994b); MDR from pea (P.M. Mullineaux, unpublished results); GST with glutathione-peroxidase activity from Arabidopsis (Bartling et al, 1993); GPX from pea (P. Mullineaux, unpublished results); LHCB (Jansson and Gustafsson, 1990); PSBA and large subunit of ribulose-I ,5-bisphosphate carboxylase oxygenase (RBCL) from Scots pine (Karpinska and Karpinski, 1993); phenylalanine ammonialyase (PAL) from Antirrhinum (Martin et al, 1991); and heat shock protein 70 (HSP 70) from pea (Domoney et al, 1991). Probes were labeled with C X -~~P -~C T P by the random primer method (Sambrook et Each RT-PCR reaction was prepared from 2.0 pg of total RNA, and cDNAs were amplified in 30 cycles in a 50-kL volume.…”