A novel mitochondrial membrane protein, Ohmm, limits fungal oxidative stress resistance and virulence in the insect fungal pathogen Beauveria bassiana

作者：He Zhangjiang; Zhang Suhong; Keyhani Nemat O; Song Yulin; Huang Shuaishuai; Pei Yan; Zhang Yongjun^*

来源：Environmental Microbiology, 2015, 17(11): 4213-4238.

DOI：10.1111/1462-2920.12713

The Hog1 mitogen-activated protein (MAP) kinase regulates environmental stress responses and virulence in the entomopathogenic fungus Beauveria bassiana. To further characterize this pathway, we constructed a subtraction library enriched for genes regulated by Hog1. One targeted gene, encoding a novel membrane protein, Ohmm (oxidative homeostasis membrane-protein-mitochondria), was uniquely identified as being downregulated in the Hog1 background during growth under non-stress and osmotic stress conditions, but upregulated under oxidative stress. Ohmm was an experimentally validated flavin-binding protein and targeted to the mitochondria. Deletion of Ohmm resulted in increased oxidative stress resistance, whereas overexpression caused an opposite phenotype. The Ohmm showed accumulation of reactive oxygen species with alterations in cell wall composition and compatible solute accumulation evident as compared with the wild type parent. Conidiation was reduced >80%; however, conidia produced by the Ohmm strain germinated significantly faster than wild type cells. Insect bioassays using the greater wax moth revealed increased virulence for the Ohmm strain in both topical and intrahemocoel injection assays, indicating a negative effect of the presence of Ohmm with respect to pathogenesis. As predicted from our characterization, deletion of Ohmm in a Hog1 background rescued its oxidative sensitivity phenotype, confirming that Ohmm acts downstream of the Hog1 MAP-kinase.

• 出版日期2015-11
• 单位西南大学