Proteomic Research of the Stress Response of Saccharomyces cerevisiae W303 Yeast to Metal Ions Eluted from Orthodontic Appliances

Although orthodontic appliances are widely used in daily practice, they also have their downsides due to the large amount of metal ions released from their surface. In this study, the influence of such released metal ions on the yeast Saccharomyces cerevisiae W303 as a model organism was investigated. Experimental yeast media in which metal ions (iron, aluminum, nickel, chromium, copper, and manganese) were eluted for 3, 7, 14, and 28 days were prepared and then used for yeast cultivation (up to the early stationary growth phase). The growth, increase, and viability of the cells were tested. The mitochondria were isolated from the spheroplasts, and the mitochondrial proteins were obtained and analyzed by liquid chromatography/mass spectrometry. Fortythree significantly altered proteins were identified. They showed significantly reduced expression in all metal-treated groups compared to the control. The metabolic processes for energy supply (glycolysis, gluconeogenesis, tricarboxylic acid cycle, and adenosine triphosphate synthesis) dominated with 50% of the total amount of significantly altered proteins in all samples, but their proportions changed at different time points. The downregulation of mitochondrial proteins such as Atp1, Atp2, and Pet9 under conditions of metal overload suggests a broader impairment of mitochondrial function. Three levels of response to stress can be observed—at relatively low metal ion concentrations in the medium (3 days of elution, approx. 3 mg/L), at medium concentrations (7 days of elution, approx. 5.5 mg/L), and at high concentrations (>8 mg/L, 14 and 28 days of elution), each affecting a specific group of proteins. The results show that mixtures of metal ions in experimental media led to a specific response (in terms of the amount and type of proteins) in each sample type to combat the provoked stress.