Oral Presentation The 5th Prato Conference on Pore Forming Proteins 2021

Insect-specific lipid-binding aegerolysin from the entomopathogenic fungus Beauveria bassiana (#22)

Nada Kraševec 1 , Špela Lemež 1 2 , Anastasija Panevska 3 , Jaka Razinger 4 , Kristina Sepčić 3 , Gregor Anderluh 1 , Marjetka Podobnik 1
  1. Department of Molecular Biology and Nanobiotechnology, National Institute of Chemistry, Ljubljana, Slovenia
  2. Biotechnology Studies, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
  3. Department of Biology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
  4. Plant Protection Department, Agricultural Institute of Slovenia, Ljubljana, Slovenia

Fungi act as decomposers, symbionts and pathogens. Among other things, they are the most common pathogens of insects and thus important regulators of their populations. Several biotic preparations containing the active ingredient of the fungus Beauveria bassiana, which acts as a bioinsecticide, have been approved. The victim of the entomopathogenic fungus dies due to vegetative overgrowth and potential toxin release into the host hemocoel, after the fungus has successfully breached the cuticle and overcome the insect’s innate immune response. Aegerolysin family proteins are well adapted to the lifestyle of the organisms that produce them and may be involved in several biologically relevant processes such as: attack and defence against other organisms, ontogenetic development or cell cycle regulation. They act alone or in concert with membrane attack complex/perforin (MACPF)-like domain-containing proteins to form pores with cytolytic or hemolytic activity. We have performed an in-depth bioinformatic analysis of aegerolysins in Fungi, with a particular focus on entomopathogenic fungi. Aegerolysins were encoded in genomes of entomopathogenic fungi such as: Beauveria, Cordyceps, Metarhizium and Ophiocordyceps. From this group of fungi, we selected a candidate aegerolysin from B. bassiana and expressed it as a recombinant protein in Escherichia coli. We purified it to further determine its functional and structural properties including lipid binding ability. The results obtained were compared with functionally related proteins: aegerolysins from white root and edible fungi, Pleurotus sp. or from the ubiquitous saprophytic filamentous fungus Aspergillus niger. We found that recombinant aegerolysin from B. bassiana has lipid- binding activity against insect-specific lipids. The paring of aegerolysins to MACPF-like domain- containing proteins also appears to be characteristic of entomopathogenic fungi. We believe that identified aegerolysins paired with MACPF-like domain- containing proteins play a role in promoting the entomopathogenic activity of these fungi.