The Elongator Subunit Elp3 Regulates Development, Stress Tolerance, Cell Cycle, and Virulence in the Entomopathogenic Fungus Beauveria bassiana

Abstract

Transcriptional activity is mediated by chromatin remodeling, which in turn is affected by post-translational modifications, including histone acetylation. Histone acetyltransferases (HATs) are capable of promoting euchromatin formation and then activating gene transcription. Here, we characterize the Elp3 GNAT family HAT, which is also a subunit of Elongator complex, in the environmentally and economically important fungal insect pathogen, Beauveria bassiana. BbElp3 showed high localization levels to mitochondria, with some nuclear and cytoplasmic localization also apparent. Targeted gene knockout of BbElp3 resulted in impaired asexual development and morphogenesis, reduced tolerances to multiple stress conditions, reduced the ability of the fungus to utilize various carbon/nitrogen sources, increased susceptibility to rapamycin, and attenuated virulence in bioassays using the greater wax moth, Galleria mellonella. The ΔBbElp3 mutant also showed disrupted cell cycle, abnormal hyphal septation patterns, and enlarged autophagosomes in vegetative hyphae. Transcriptome analyses revealed differential expression of 775 genes (DEGs), including 336 downregulated and 438 upregulated genes in the ΔBbElp3 strain as compared to the wild type. Downregulated genes were mainly enriched in pathways involved in DNA processing and transcription, cell cycle control, cellular transportation, cell defense, and virulence, including hydrophobins, cellular transporters (ABC and MFS multidrug transporters), and insect cuticular degrading enzymes, while upregulated genes were mainly enriched in carbohydrate metabolism and amino acid metabolism. These data indicate pleiotropic effects of BbElp3 in impacting specific cellular processes related to asexual development, cell cycle, autophagy, and virulence.

Aspergillus fumigatus Elongator complex subunit 3 affects hyphal growth, adhesion and virulence through wobble uridine tRNA modification

“…bacteria [23]. Disruption of Elp3 results in pleiotropic phenotypes, including inhibited growth and development and altered stress responses in plants and fungi [27,[33][34][35][36]. Similarly, our phenotypic characterization revealed that loss of Elp3 leads to reduced hyphal growth and spore production in A. fumigatus (Fig 1…”

“…As a catalytic subunit of the Elongator complex, Elp3 is present in all three domains of life, including all archaea and some clades of bacteria [ 23 ]. Disruption of Elp3 results in pleiotropic phenotypes, including inhibited growth and development and altered stress responses in plants and fungi [ 27 , 33 – 36 ]. Similarly, our phenotypic characterization revealed that loss of Elp3 leads to reduced hyphal growth and spore production in A .…”

Proteomic analysis revealed the function of PoElp3 in development, pathogenicity, and autophagy through the tRNA-mediated translation efficiency in the rice blast fungus

“…2000), Fusarium graminearum (Lee et al . 2014) and Beauveria bassiana (Cai et al . 2022), but not in Aspergillus fumigatus (Zhang et al .…”

“…However, the effect of Elp3 on histone acetylation could be altered in different organisms, in suggestive of diverse regulatory mechanisms in different backgrounds. For example, the H3K14ac level was significantly reduced in S. cerevisiae (Wittschieben et al 2000), Fusarium graminearum (Lee et al 2014) and Beauveria bassiana (Cai et al 2022), but not in Aspergillus fumigatus (Zhang et al 2022) and Pyricularia oryzae (Zhang et al 2021). Elp3 also possesses a radical S-adenosylmethionine (SAM) domain, which is responsible for the modification of wobble uridine residues in eukaryotic tRNA (Dauden et al 2019;Lin et al 2019;Abbassi et al 2020).…”

Entomopathogenic Fungi in Biological Plant Protection: The Machinery of Multicomponent System Interactions

“…Researchers established that the Slt2-MAPK signalling pathway and the transcription factor RNS1 controlled conidiation in Metarhizium robertsii via direct regulation of the central regulatory pathway [ 3 ]. They also identified the elongator subunit (Elp3) that regulates development, stress tolerance, cell cycle and virulence in Beauveria bassiana [ 4 ]. MicroRNAs involved in immunity and development were found to participate in the modulation of M. anisopliae–Plutella xylostella interactions [ 5 ].…”