Characterization of a second gene encoding γ-glutamyl transpeptidase from Schizosaccharomyces pombe

Abstract

The first gene encoding gamma-glutamyl transpeptidase (GGTI) of the fission yeast has previously been characterized, and its expression was found to be regulated by various oxidative stress-inducing agents. In this work, a second gene, encoding GGTII, was cloned and characterized from the fission yeast Schizosaccharomyces pombe. The structural gene encoding GGTII was amplified from the genomic DNA of the fission yeast and ligated into the shuttle vector pRS316 to generate the recombinant plasmid pPHJ02. The determined sequence contains 3040 bp and is able to encode the putative 611 amino acid sequence of GGTII, which resembles the counterparts of Saccharomyces cerevisiae, Homo sapiens, Rattus norvegicus, and Escherichia coli. The DNA sequence also contains 940-bp upstream and 289-bp downstream regions of the GGTII gene. The Schizosaccharomyces pombe cells harboring plasmid pPHJ02 showed about 4-fold higher GGT activity in the exponential phase than the cells harboring the vector only, indicating that the cloned GGTII gene is functional. The S. pombe cells containing the cloned GGTII gene were found to contain higher levels of both intracellular glutathione (GSH) content and GSH uptake. The S. pombe cells harboring plasmid pPHJ02 showed increased survival on solid media containing hydrogen peroxide, diethylmaleate, aluminum chloride, cadmium chloride, or mercuric chloride. The GGTII mRNA level was significantly elevated by treatment with GSH-depleting diethylmaleate. These results imply that the S. pombe GGTII gene produces functional GGTII protein and is involved in the response to oxidative stresses in S. pombe cells.

Quantitative proteomics reveals new insights into calcium-mediated resistance mechanisms in Aspergillus flavus against the antifungal protein PgAFP in cheese

“…The proteins related to glutathione metabolism have been shown to be important in the maintenance of the redox status upon oxidative stress in fungi (Kang et al, 2005;Park et al, 2005Park et al, , 2004Springael and Penninckx, 2003). Thus, the higher relative abundance of these proteins could be related to the successful response of A. flavus to PgAFP in the calcium-enriched culture medium.…”

Comparative genomics of duplicate γ‐glutamyl transferase genes in teleosts: medaka (Oryzias latipes), stickleback (Gasterosteus aculeatus), green spotted pufferfish (Tetraodon nigroviridis), fugu (Takifugu rubripes), and zebrafish (Danio rerio)

“…GGT gene/protein sequences are found in most species examined including archaebacteria, eubacteria, protocysts, yeast, insects, and vertebrates, suggesting a basic conserved function for these enzymes throughout evolution (Suzuki et al, '89; Chikhi et al, '99; Park et al, 2005). GGT initiates the glutathione degradation in extracellular matrix by cleaving the glutamyl bond of glutathione or glutathione conjugates, producing cysteinyl‐glycine.…”