Antioxidant System Response of Yarrowia lipolytica Cells Under Oxidative Stress

Eukaryotic cells respond to oxidative stress (OS), a physiological condition characterized by the accumulation of reactive oxygen species (ROS), through various protective mechanisms. The antioxidant defense system (ADS) is activated either by post-translational modifications of pre-existing proteins or through the induction of gene expression. These mechanisms protect cellular biomolecules against ROS damage. Although extensive research has been conducted in different species, there is limited information regarding the specific response of Yarrowia lipolytica to OS. This study aims to elucidate the molecular mechanisms by which Y. lipolytica responds to OS by analyzing the expression of genes encoding enzymes involved in antioxidant response, such as superoxide dismutase (Sod), catalase (Cat), and glutathione peroxidase (Gpx). The Y. lipolytica genome contains three CAT genes, one SOD gene, one copper chaperone for Sod (CCS) gene, and one GPX gene. The expression profiles of these genes were assessed in Y. lipolytica cells exposed to H₂O₂ [5 mM] over time. All genes reached their maximal expression within the first 15 min of exposure. Comparative analysis between young and aged Y. lipolytica cells subjected to OS revealed that young cells exhibited higher expression levels for all genes, with CAT3 and SOD showing the highest expression values. These findings suggest that the enzymes encoded by these genes play a crucial role in the antioxidant response of this species. To our knowledge, this is the first study demonstrating that the ADS in Y. lipolytica is regulated at the transcriptional level.