AUTHOR=Wang Zhangxun , Chen Hua , Li Hao , Chen Hanyuan , Huang Bo 

TITLE=The Deubiquitinating Enzyme MrUbp14 Is Involved in Conidiation, Stress Response, and Pathogenicity in Metarhizium robertsii

JOURNAL=Frontiers in Fungal Biology

VOLUME=3

YEAR=2022

URL=https://www.frontiersin.org/journals/fungal-biology/articles/10.3389/ffunb.2022.896466

DOI=10.3389/ffunb.2022.896466

ISSN=2673-6128

ABSTRACT=<p>Protein ubiquitination, which is involved in various biological processes in eukaryotic cells, is a reversible modification of proteins. Deubiquitinases can maintain ubiquitin homeostasis by removing ubiquitin or modulating protein degradation <italic>via</italic> the ubiquitin-proteasome system (UPS). <italic>Metarhizium robertsii</italic>, an entomopathogenic fungus, has become a model fungus for investigating the interactions between insects and fungal pathogens. To explore the possible effects of the deubiquitination process on the development, stress response, and virulence of <italic>M. robertsii</italic>, disruption of <italic>MrUbp14</italic> (an ortholog of the yeast ubiquitin-specific protease gene, <italic>Ubp14</italic>) was performed. The results of this study showed that the deletion of <italic>MrUbp14</italic> led to accelerated conidial germination, reduced conidial yields, and decreased expression levels of some genes involved in conidiation. Furthermore, the <italic>MrUbp14</italic> mutant (Δ<italic>MrUbp14</italic>) exhibited decreased tolerance to cell wall-damaging stressors (Congo red and SDS) and heat stress. Importantly, the results of the bioassay demonstrated that the fungal virulence of the Δ<italic>MrUbp14</italic> strain was largely reduced in cuticle infection, but not in direct injection, which was accompanied by a significant decline in appressorium formation and cuticle penetration. Moreover, our results demonstrated that the disruption of <italic>MrUbp14</italic> resulted in significantly increased ubiquitination levels of total protein, suggesting that MrUbp14 acts as a deubiquitinating enzyme in <italic>M. robertsii</italic>. In summary, our phenotypic changes in the gene disruption mutants suggest that <italic>MrUbp14</italic> is important for conidiation, stress response, and fungal virulence in <italic>M. robertsii</italic>.</p>