Sensitivity to Sn2+ of the Yeast Saccharomyces cerevisiae Depends on General Energy Metabolism, Metal Transport, Anti-Oxidative Defences, and DNA Repair
Resistance to stannous chloride (SnCl2) of the yeast Saccharomyces cerevisiae is a product of several metabolic pathways of this unicellular eukaryote. Sensitivity testing of different null mutants of yeast to SnCl2 revealed that DNA repair contributes to resistance, mainly via recombinational (Rad52p) and error-prone (Rev3p) steps. Independently, the membrane transporter Atr1p/Snq1p (facilitated transport) contributed significantly to Sn2+-resistance whereas absence of ABC export permease Snq2p did not enhance sensitivity. Sensitivity of the superoxide dismutase mutants sod1 and sod2 revealed the importance of these anti-oxidative defence enzymes against Sn2+-imposed DNA damage while a catalase-deficient mutant (ctt1) showed wild type (WT) resistance. Lack of transcription factor Yap1, responsible for the oxidative stress response in yeast, led to 3-fold increase in Sn2+-sensitivity. While loss of mitochondrial DNA did not change the Sn2+-resistance phenotype in any yeast strain, cells with defect cytochrome c oxidase (CcO mutants) showed gradually enhanced sensitivities to Sn2+ and different spontaneous mutation rates. Highest sensitivity to Sn2+ was observed when yeast was in exponential growth phase under glucose repression. During diauxic shift (release from glucose repression) Sn2+-resistance increased several hundred-fold and fully respiring and resting cells were sensitive only at more than 1000-fold exposure dose, i.e. they survived better at 25 mM than exponentially growing cells at 25 μM Sn2+. This phenomenon was observed not only in WT but also in already Sn2+-sensitive rad52 as well as in sod1, sod2 and CcO mutant strains. The impact of metabolic steps in contribution to Sn2+-resistance had the following ranking: Resting WT cells > membrane transporter Snq1p > superoxide dismutases > transcription factor Yap1p ≥ DNA repair \( \gg \) exponentially growing WT cells.
Keywordscytochrome oxidase DNA repair genotoxicity glucose repression membrane transport oxidative stress stannous chloride yeast
Unable to display preview. Download preview PDF.
- Alseth I, Eide L, Pirovano M, Rognes T, Seeberg E, Bjoras M (1999) The Saccharomyces cerevisiae homologues of endonuclease III from Escherichia coli, Ntg1 and Ntg2, are both required for efficient repair of spontaneous and induced oxidative DNA damage in yeast. Mol Cell Biol 19:3779–3787PubMedGoogle Scholar
- Burke D, Dawson D. Stearns T (2000) Methods in yeast genetics. Cold Spring Harbour Laboratory Course Manual, CSH Laboratory Press, N.YGoogle Scholar
- De Winde JH, Thevelein JM, Winderickx J (1997) From feast to famine: adaptation to nutrient depletion in yeast. In: Hohmann S, Mager WH (eds) Yeast Stress Responses. Springer, Berlin, Heidelberg, New York, pp 7–52Google Scholar
- Eide D, Guerinot ML (1997) Metal ion uptake in eukaryotes: research on Saccharomyces cerevisiae reveals complexity and insights about other species. ASM News 63:199–205Google Scholar
- Fuge EK, Werner-Washburne M (1997) Stationary phase in the yeast Saccharomyces cerevisiae. In: Hohmann S, Mager WH (eds) Yeast Stress Responses. Springer, Berlin, Heidelberg New York, pp 53–74Google Scholar
- McLean JR, Kaplan JG (1979) The effect of tin on unscheduled and semi-conservative DNA synthesis. In: Kaplan JG (ed) The Molecular Basis of Immune Cell Function. Elsevier Biomedical, AmsterdamGoogle Scholar
- Pungartnik C, Viau C, Picada J, Caldeira-de-Araújo A, Henriques JAP, Brendel M. 2005 Genotoxicity of stannous chloride in yeast and bacteria. Mutat Res 583, 146–157Google Scholar
- Viau CM, Yoneama ML, Dias JF, Pungartnik C, Brendel M, Henriques JAP (2005) Detection and quantitative determination by PIXE of the mutagen Sn2+ in yeast cells. Nucl. Instrum Meth Physics Res B, in pressGoogle Scholar
- von Borstel RC, Cain KT, Steinberg CM (1971) Inheritance of spontaneous mutability in yeast. Genetics 69:17–27Google Scholar
- Wehner EP, Rao E, Brendel M (1983) Molecular structure and genetic regulation of SFA, a gene responsible for resistance to formaldehyde in Saccharomyces cerevisiae. Mol Gen Genet 237:351–358Google Scholar