Peroxins in Peroxisomal Receptor Export System Contribute to Development, Stress Response, and Virulence of Insect Pathogenic Fungus Beauveria bassiana

Abstract

In filamentous fungi, recycling of receptors responsible for protein targeting to peroxisomes depends on the receptor export system (RES), which consists of peroxins Pex1, Pex6, and Pex26. This study seeks to functionally characterize these peroxins in the entomopathogenic fungus Beauveria bassiana. BbPex1, BbPex6, and BbPex26 are associated with peroxisomes and interact with each other. The loss of these peroxins did not completely abolish the peroxisome biogenesis. Three peroxins were all absolutely required for PTS1 pathway; however, only BbPex6 and BbPex26 were required for protein translocation via PTS2 pathway. Three gene disruption mutants displayed the similar phenotypic defects in assimilation of nutrients (e.g., fatty acid, protein, and chitin), stress response (e.g., oxidative and osmotic stress), and virulence. Notably, all disruptant displayed significantly enhanced sensitivity to linoleic acid, a polyunsaturated fatty acid. This study reinforces the essential roles of the peroxisome in the lifecycle of entomopathogenic fungi and highlights peroxisomal roles in combating the host defense system.

Unlocking the Siderophore Biosynthesis Pathway and Its Biological Functions in the Fungal Insect Pathogen Beauveria bassiana

“…46,47 After the death of the hosts, B. bassiana shifts to saprotrophic growth on the cadaver and generates conidia via asexual development, which is essential for fungal dispersal and new infection cycle. 27 Only BbSidA significantly contributes to conidiation. From this perspective, BbSidA plays a critical role in making the infection cycle run properly.…”

“…Fungal phenotypes were determined among the WT, gene disruption, and complemented mutant strains as described previously with three replicates. 27 Assays for ΔBbsidC and ΔBbsidD were performed with three independent disruptants due to the absence of the complementation mutant strains.…”