Ascorbic Acid and Thiol Antioxidants Suppress Spontaneous Mutagenesis in a Cu,Zn-superoxide Dismutase-deficient Mutant of Saccharomyces cerevisiae

Abstract

Cu,Zn-superoxide dismutase (SOD1) is a critical enzyme in the cellular antioxidant system. The yeast Saccharomyces cerevisiae SOD1 mutant (SOD1D) exhibits a moderate mutator phenotype under aerobic conditions. The mutation frequency of a SOD1D strain determined by a CAN1 forward-mutation assay was about 12-fold higher than that of the parental strain. Base substitutions G･C→ T･A, G･C→A･T, and A･T→C･G were most commonly observed in CAN1 mutants, indicating that the mutations are caused mainly by oxidative DNA damage. The mutation frequency of SOD1D was reduced in a dose-dependent manner by cultivating it in the presence of ascorbic acid, implying that the SOD1D mutant can be used as a tester strain for small molecule antioxidants. Exogenous glutathione and N-acetylcystein also alleviated the mutator phenotype. The results indicate that ascorbic acid and thiol antioxidants are able to e‹ciently protect cells against oxidative damage-induced mutagenesis. In this assay, no apparent mutation suppression was seen for other categories of antioxidants including resveratrol, Trolox and melatonin.

Suppressive Effects of Natural Compounds on Methionine Auxotrophy of a Cu,Zn-Superoxide Dismutase-Deficient Mutant of <i>Saccharomyces cerevisiae</i>

“…These antioxidants have been demonstrated to have effective antioxidant activities in various in vitro assays, and most compounds are ingredients in commercially available dietary supplements (Bouayed and Bohn, 2010;Bergström et al, 2012;Sadowska-antioxidants (AsA and thiol antioxidants) can suppress Met auxotrophy of the sod1∆ strain by exogenous supplementation. The same pattern of antioxidant action was found when studying the restoration of sod1∆ from oxidative stress-sensitive phenotypes (Lewinska et al, 2004;Kozioł et al, 2005;Tamura et al, 2010;Kwolek-Mirek et al, 2012) and a mutator phenotype (Nagira et al, 2013).…”

“…The sod1∆ strain used here was obtained from the collection of the Saccharomyces Genome Deletion Project, and exhibited Met auxotrophy under atmospheric oxygen levels, as well as sensitivity to oxygen and hypertonic stress, and a mutator phenotype (Tamura et al, 2010;Nagira et al, 2013). In the present study, we modified the method of Zyracka et al (2005a;2005b) and thrombosis (Wierzbicki, 2007;Cattaneo, 1999).…”

“…The yeast Saccharomyces cerevisiae lacking Cu, has a number of oxygen-dependent defects, including sensitivity to oxygen, redox cycling drugs, and hyperosmotic stress (Chang et al, 1991;Krasowska et al, 2003;Kozioł et al, 2005;Saffi et al, and Valentine, 1991;Nagira et al, 2013), metabolic alterations including auxotrophy for the amino acids Lys and Met (Chang and Kosman, 1990;Wallace et al, 2004;Sehati et al, 2011), and shortening of the replicative life span (Krzepiłko et al, 2004;Owsiak et al, 2010). These detrimental phenotypes of sod1∆ could be alleviated by the addition of vitamin C (ascorbic acid, AsA), suggesting the possibility that the yeast mutant can be used as a biosensor for low molecular weight antioxidants (Zyracka et al, 2005b;Tamura et al, 2010;Nagira et al, 2013).…”

“…These detrimental phenotypes of sod1∆ could be alleviated by the addition of vitamin C (ascorbic acid, AsA), suggesting the possibility that the yeast mutant can be used as a biosensor for low molecular weight antioxidants (Zyracka et al, 2005b;Tamura et al, 2010;Nagira et al, 2013).…”