Nucleotide Sequence of the Gene for a Glutathione S-Transferase from Cell Suspension Cultures of Silene cucubalus.

Glutathione S-transferases (4) are involved in numerous plant physiological processes such as herbicide resistance (8), senescing flower petal response to ethylene (7), host response to pathogenic attack (2), and mammalian systems in the detoxification of xenobiotics. It has also been proposed that human glutathione S-transferase interacts with mercury, copper, and cadmium, therefore becoming a part of the heavy metal detoxification system (1). The gene sequences of only a limited number of members of this multigene family have been reported in the literature. To date, there is sequence information available for a maize gene (3, 10) and two wheat genes (gstAl [2] and gstA2 [6]) encoding various glutathione S-transferase isozymes. We report here the nucleotide sequence of a gene coding for a constitutive glutathione Stransferase from cell suspension cultures of the Alpen Leimkraut, Silene cucubalus (Fig. 1, Table I). The gene sequence contained 2507 nucleotides from the 5'-flanking region and 1191 nucleotides from the 3'-flanking region. The open reading frame was interrupted by two introns, intron I being 1719 nucleotides long and intron II 116 nucleotides long. When a 2513-nucleotide segment of the 5'-untranslated region was fused in front of a gene for 13-glucuronidase and transformed into Nicotiana plumbaginifolia protoplasts, promoter activity equal to 70% of the 35S cauliflower mosaic virus promoter was detected. The nucleotide sequence within the reading frame was 51.9% homologous to the wheat gstA2 gene when compared by the Needleman-Wunsch algorithm (9).