Deletion of MET4 gene decreases tolerance to cadmium ions and their accumulation in yeast cells of Hansenula polymorpha and Saccharomyces cerevisiae
Institute of Biology IV- Microbiology and Genetics RWTH Aachen
Worringerweg 1, Aachen D-52056, Germany
The participation of the central regulatory gene of sulfur metabolism, ╠┼Ď4, in intracellular cadmium ion accumulation and in maintenance of cadmium ion tolerance was examined. It was shown that deletion of Hansenula polymorpha MET4 gene increased sensitivity of Δmet4 mutant to cadmium ions, while overexpression of this gene in mcMET4 transformant increased its resistance to cadmium. Cadmium ion accumulation study revealed that H. polymorpha mcGSH2 transformant, with overexpressed gene of the first step of glutathione biosynthesis, and both Δmet4 mutants of yeasts H. olymorpha and Saccharomyces cerevisiae exhibited decreased glucose-dependent absorption of cadmium ions, compared to the correspondent wild type strains. It was hypothesized that ╠┼Ď4 gene is involved in maturation of cellular Cd-GSH complex, which in turn regulates cadmium ion uptake.
Keywords: MET4, cadmium, Hansenula olymorpha, Saccharomyces cerevisiae