Evaluation of the Role of Glutathione in the Lead-Induced Toxicity in Saccharomyces cerevisiae Rita R. Perez • Ca ´tia A. Sousa • Thomas Vankeersbilck • Manuela D. Machado • Eduardo V. Soares Received: 17 December 2012 / Accepted: 5 March 2013 / Published online: 17 April 2013 Ó Springer Science+Business Media New York 2013 Abstract The effect of intracellular reduced glutathione (GSH) in the lead stress response of Saccharomyces cere- visiae was investigated. Yeast cells exposed to Pb, for 3 h, lost the cell proliferation capacity (viability) and decreased intracellular GSH level. The Pb-induced loss of cell via- bility was compared among yeast cells deficient in GSH1 (Dgsh1) or GSH2 (Dgsh2) genes and wild-type (WT) cells. When exposed to Pb, Dgsh1 and Dgsh2 cells did not dis- play an increased loss of viability, compared with WT cells. However, the depletion of cellular thiols, including GSH, by treatment of WT cells with iodoacetamide (an alkylating agent, which binds covalently to thiol group), increased the loss of viability in Pb-treated cells. In con- trast, GSH enrichment, due to the incubation of WT cells with amino acids mixture constituting GSH (L-glutamic acid, L-cysteine and glycine), reduced the Pb-induced loss of proliferation capacity. The obtained results suggest that intracellular GSH is involved in the defence against the Pb- induced toxicity; however, at physiological concentration, GSH seems not to be sufficient to prevent the Pb-induced loss of cell viability. Introduction Although lead occurs naturally, its presence in the envi- ronment comes, mainly, from human activities, like mining or smelting of ore, manufacture of lead-containing products (such as car batteries), combustion of coal and oil, and waste incineration. Lead is a non-essential metal for bio- logical functions and is classified by the International Agency for Research on Cancer as probable human car- cinogen [1]. The yeast Saccharomyces cerevisiae is a suitable eukaryotic model organism for studying Pb toxic effects, since its cellular structure and functional organization share many similarities with animal and plant cells. This yeast can be easily manipulated, presents a short generation time and has the genome completely sequenced. In addition, valuable tools are available such as the yeast deletion strain collection for understanding gene functions [22]. In S. cerevisiae, Pb inhibits metabolic activity [23] and cell growth, impairs ammonium assimilation and reduces DNA/RNA ratio [4]. In addition, it was shown that Pb induces the intracellular accumulation of reactive oxygen species (ROS), which can be the trigger of programmed cell death by apoptosis [3]. Yeast cells have different protection mechanisms for controlling the levels of ROS, which can be, basically, divided in enzymatic (superoxide dismutases, catalases and peroxidases) and non-enzymatic defences (as glutathione and trehalose) [10, 12]. The tripeptide glutathione (L-c-glutamyl-L-cysteinyl- glycine) is the main intracellular low molecular mass thiol. R. R. Perez Á C. A. Sousa Á T. Vankeersbilck Á M. D. Machado Á E. V. Soares (&) Bioengineering Laboratory-CIETI, Chemical Engineering Department, ISEP-School of Engineering of Polytechnic Institute of Porto, Rua Dr Anto ´nio Bernardino de Almeida, 431, 4200-072 Porto, Portugal e-mail: evs@isep.ipp.pt T. Vankeersbilck Department Industrial Engineering, KaHo St.-Lieven, Gebroeders Desmetstraat 1, 9000 Ghent, Belgium M. D. Machado Á E. V. Soares IBB-Institute for Biotechnology and Bioengineering, Centre for Biological Engineering, Universidade do Minho, Campus de Gualtar, 4710-057 Braga, Portugal 123 Curr Microbiol (2013) 67:300–305 DOI 10.1007/s00284-013-0364-z