Targeting Genes of Cd Induced Oxidative Stress Response in Yeasts

ABSTRACT

The microbial biosynthesis of nanoparticles has become one of the most studied fields of nanobiotechnology. However, exposure of cells to heavy metals and matalloides profoundly affects biological systems as it generally leads to intracellular oxidative damage and strongly depends on the cellular metabolic status. In this respect, the cadmium resistance of 7 yeast species differing in their type of glucose oxidation and energy generation (Saccharomyces cerevisiae, Candida glabrata, Schizosaccharomyces pombe, Pichia pastoris, Hansenula polymorpha, Kluyveromyces lactis and Rhodotorula graminis) was studied. It was shown that the cellular growth of S. pombe and C. glabrata was not significantly impaired when high Cd concentration was applied. Unusually elevated survival levels were also detected in H. polymorpha and R. graminis yeasts. To further investigate the cellular resistance to Cd ions, a comprehensive in silico analysis of key antioxidant enzymes were performed. Applying a computational approach, it was shown that Crabtree positive Schizosaccharomyces pombe and Candida glabrata, as well as the oxidative yeast Rhodotorula graminis possess genetically determined advantages for surviving when higher concentrations of toxic Cd ions are present in the environment: existence of duplicated copies of genes encoded key antioxidant enzymes (catalases, glutathione peroxidases and glutathione S-transferases). Moreover, the proteins involved in cellular antioxidant defence in those yeast species possess numerous targeting signals allowing their localization plasticity in different subcellular structures. In spite of the lack of antioxidant genetic advantages, Hansenula polymorpha also revealed high Cd resistance.

Keywords:

• yeasts
• cadmium
• metal toxicity
• in silico analysis
• antioxidant enzymes