A second stress-inducible glutathione S-transferase gene from Schizosaccharomyces pombe

A second glutathione S-transferase gene (GST II) was isolated from the chromosomal DNA of the fission yeast Schizosaccharomyces pombe. The nucleotide sequence determined contains 1908 bp including an open reading frame of 230 amino acids that would encode a protein of a molecular mass of 26843.4 Da. The amino acid sequence of the putative GST II is very homologous with that of the previously isolated GST gene (GST I) located in the same chromosome III of S. pombe. The cloned GST II gene produces the functional GST in S. pombe, and it gives much higher GST in the stationary phase than in the exponential phase. Regulation of the GST II gene was studied using the GST II-lacZ fusion. The synthesis of beta-galactosidase from the fusion plasmid is greatly enhanced by the treatments with oxidative stresses such as menadione and mercuric chloride. It is also induced by o-dinitrobenzene, one of the GST substrates. NO-generating S-nitroso-N-acetylpenicillamine has a weak induction effect on the expression of GST II gene. These results indicate that the S. pombe GST II gene is involved in the oxidative stress response and detoxification. However, physiological meaning on the existence of the two similar GST genes in S. pombe remains unknown yet.