A novel mitochondrial membrane protein, Ohmm, limits fungal oxidative stress resistance and virulence in the insect fungal pathogen Beauveria bassiana
A novel mitochondrial membrane protein, Ohmm, limits fungal oxidative stress resistance and virulence in the insect fungal pathogen Beauveria bassiana
复制标题
一种新型线粒体膜蛋白 Ohmm 限制了昆虫真菌病原体白僵菌的真菌氧化应激抵抗力和毒力
DOI：
10.1111/1462-2920.12713
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发表时间：
2015-11-01
影响因子：
5.1
通讯作者：
Zhang, Yongjun
中科院分区：
文献类型：
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作者：
He, Zhangjiang;Zhang, Suhong;Zhang, Yongjun
Hog1丝裂原活化蛋白（MAP）激酶调控球孢白僵菌这种昆虫病原真菌对环境胁迫的响应及毒力。为进一步阐明该信号通路，我们构建了一个富集Hog1调控基因的消减文库。其中一个目标基因编码一种新型膜蛋白Ohmm（氧化稳态膜蛋白 - 线粒体蛋白），经鉴定，在非胁迫及渗透胁迫条件下生长时，该基因在Hog1缺失背景中表达下调，而在氧化胁迫下表达上调。Ohmm是一种经实验验证的黄素结合蛋白，定位于线粒体。敲除Ohmm导致氧化胁迫抗性增强，而过表达则产生相反的表型。与野生型亲本相比，Ohmm表现出活性氧积累，细胞壁成分改变，相容性溶质积累明显。产孢量减少超过80%；然而，Ohmm缺失菌株产生的分生孢子萌发速度显著快于野生型细胞。以大蜡螟进行的昆虫生物测定显示，在体表接种和血腔注射试验中，Ohmm缺失菌株的毒力均有所增强，表明Ohmm的存在对致病过程有负面影响。正如我们根据特性分析所预测的，在Hog1缺失背景中敲除Ohmm可挽救其氧化敏感表型，证实Ohmm在Hog1 MAP激酶下游发挥作用。
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.