Sterol Regulatory Element-Binding Protein, BbSre1, Controls Oxidative Stress Response, Peroxisome Division, and Lipid Homeostasis in an Insect Fungal Pathogen.

Sterol regulatory element-binding protein, Sre1, regulates sterol biosynthesis, lipid metabolism, hypoxia adaptation, and virulence in some fungi, even though its roles are varied in fungal species. However, few studies report its other functions in fungi. Here, we report novel roles of Sre1 homolog, BbSre1, in the insect fungal pathogen, Beauveria bassiana , that regulates oxidative stress response, peroxisome division, and redox homeostasis. The gene disruption stain showed increased sensitivity to oxidative stress, which was in line with oxidative stress-induced-BbSre1 nuclear import and control of antioxidant and detoxification-involved genes. The gene mutation also inhibited peroxisome division, affected redox homeostasis, and impaired lipid/fatty acid metabolism and sterol biosynthesis, which was verified by downregulation of their associated genes. These data broaden our understanding of role of Sre1, which regulates peroxisome division, antioxidant, and detoxification-involved genes for control of redox homeostasis and oxidative stress response that links to lipid/fatty acid metabolism and sterol biosynthesis.