Abstract
The transcription factor SKN7 is a highly conserved protein among fungi and was initially recognized as a response regulator that protects cells from oxidative stress and maintains cell wall integrity in yeast. Orthologs of SKN7 are extensively present in biocontrol agents of plant pathogens, but they had not been functionally characterized. Here, we identified and characterized the transcription factor SKN7 in the nematode endoparasitic fungus Hirsutella minnesotensis. Null mutant lacking HIM-SKN7 (HIM_03620), which was generated by a gene disruption strategy, demonstrated reduced conidiation, increased sensitivity to high temperature, hydrogen peroxide, mannitol and ethanol, and reduced fungal resistance to farnesol. However, over-expression mutant showed increased conidial production, thermotolerance and resistance to farnesol, suggesting that HIM-SKN7 regulates antiapoptotic-like cell death in H. minnesotensis. Moreover, the results showed that in null mutant, H. minnesotensis had decreased endoparasitic ability as compared to wild type and over-expression strain. During the infection process, the relative expression of the HIM-SKN7 gene was significantly induced in the wild type and over-expression strain. The results of the present study advance our understanding of the functions of the SKN7 gene in biocontrol agents, in particular, nematode endoparasitic fungi.
Highlights
Heat shock proteins are a conserved family of proteins that are encoded by several heat shock genes
Skn[7] is a stress-responsive transcription factor with a uniform architecture that is composed of a N-terminal DNA binding domain that is homologous to a heat shock transcription factor (HSF) and a C-terminal receiver domain[14]
It has been revealed that SKN7 and HSF1 collaborate to achieve the maximal induction of heat shock genes in response to oxidative stress[16], and the disruption of SKN7 in Saccharomyces cerevisiae resulted in sensitivity to oxidizing agents and the induction of TRX2 genes[17]
Summary
Heat shock proteins are a conserved family of proteins that are encoded by several heat shock genes. Skn[7] is a stress-responsive transcription factor with a uniform architecture that is composed of a N-terminal DNA binding domain that is homologous to a heat shock transcription factor (HSF) and a C-terminal receiver domain[14] These domains are highly conserved among fungi. In the human fungal pathogen Cryptococcus neoformans, SKN7 mutants were less virulent and sensitive to reactive oxygen species, as compared to those with wild-type[21] These results suggest that SKN7 plays functional roles in the response to different stresses and might be involved in the expression of genes that regulate the cell wall. We have functionally characterized a gene within the H. minnesotensis wild type strain, WT-3608, encoding a HSF-type DNA-binding domain along with REC (signal receiver domain), and designated it as transcription factor, HIM-SKN7. We developed HIM-SKN7 knockout and over-expression mutant of H. minnesotensis WT-3608 and found that HIM-SKN7 regulates conidiation, thermotolerance, abiotic stress resistance, antiapoptotic like cell death and nematode endoparasitic efficiency
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
