INO2 mutation in Saccharomyces cerevisiae

Effects on ER stress and membrane integrity

Abstract

INO2 plays a crucial role in regulating phospholipid and fatty acid biosynthesis. Previous research indicates ino2-Δ mutants have reduced lipid levels, leading to compromised cell membrane integrity. We hypothesize that an imbalance in lipids may cause stress on the endoplasmic reticulum (ER) membrane, resulting in the activation of the ER-associated degradation pathway and in the early ubiquitination of ER proteins. Thus, we measured ubiquitin levels of Saccharomyces cerevisiae as an indirect indicator of ER stress induced by ino2-Δ and were analysed via Western blotting. Additionally, to evaluate cell viability and membrane perturbation, propidium iodide staining with fluorescence microscopy was conducted. Contrary to our hypothesis, significant differences between the ubiquitin levels of wildtype and mutant strains were not observed. This suggests that under the conditions examined, the mutation does not markedly influence ER stress or compromises cell membrane integrity. This observation supports the phenomenon where exogenous lipid supplementation–such as YPD–may bypass the effects of the mutation, preserving cell membrane integrity. The findings of this study enhance our understanding on the crucial role of the effects of nutrient availability on the integrity of yeast cell membrane.