title: The Bax inhibitor MrBI-1 regulates heat tolerance, apoptotic-like cell death, and virulence in Metarhizium robertsii.
abstract: Bax inhibitor 1 (BI-1) is a highly conserved protein originally identified as a suppressor of the proapoptotic protein Bax to inhibit cell death in animals and plants. The orthologs of BI-1 are widely distributed in filamentous fungi but their functions remain largely unknown. Herein, we report the identification and characterizations of MrBI-1, an ortholog of BI-1, in the entomopathogenic fungus Metarhizium robertsii. First, we found that MrBI-1 could partially rescue mammalian Bax-induced cell death in yeast. Deletion of MrBI-1 impaired fungal development, virulence and heat tolerance in M. robertsii. We also demonstrated that inactivation of MrBI-1 reduced fungal resistance to farnesol but not to hydrogen peroxide, suggesting that MrBI-1 contributes to antiapoptotic-like cell death via the endoplasmic reticulum stress-signaling pathway rather than the classical mitochondrium-dependent pathway. In particular, we found that unlike the observations in yeasts and plants, expression of mammalian Bax did not lead to a lethal effect in M. robertsii; however, it did aggravate the fungal apoptotic effect of farnesol. The results of this study advance our understanding of BI-1-like protein functions in filamentous fungi.
authors.affiliation: Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China.
authors.forename: Yixiong
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China.|Current address:Department of Neuroscience &Cell Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway NJ, 08854, USA.
authors.forename: Zhibing
authors.initials: Z
authors.lastname: Duan
authors.affiliation: Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China.
authors.forename: Peilin
authors.initials: P
authors.lastname: Chen
authors.affiliation: Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China.
authors.forename: Yanfang
authors.initials: Y
authors.lastname: Shang
authors.affiliation: Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China.
authors.forename: Chengshu
authors.initials: C
authors.lastname: Wang
mesh_terms: D000220:Adaptation, Biological; D017209:Apoptosis; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D006358:Hot Temperature; D006861:Hydrogen Peroxide / Q000494:pharmacology; D052981:Metarhizium / Q000145:classification / Q000187:drug effects / Q000472:pathogenicity / Q000502:physiology*; D050296:Microbial Viability / Q000187:drug effects / Q000235:genetics; D010641:Phenotype; D010802:Phylogeny; D054730:Protein Interaction Domains and Motifs; D013172:Spores, Fungal; D014774:Virulence; D051028:bcl-2-Associated X Protein / Q000037:antagonists & inhibitors* / Q000378:metabolism
chemical_list: D005656:Fungal Proteins; D051028:bcl-2-Associated X Protein; D006861:Hydrogen Peroxide