Aegerolysins are relatively small (15 kDa) proteins with unique biotechnological potential. Their most prominent feature is a high affinity for specific membrane lipids or lipid combinations. Aegerolysins are non-toxic and can be easily produced in recombinant form. In some aegerolysin-production organisms, aegerolysins co-occur with proteins bearing the Membrane Attack Complex / Perforin (MACPF) domain.
The aegerolysins known to date are characterised by their high affinity for ceramide phosphoethanolamine (CPE), an insect-specific membrane sphingolipid. In addition, some of these aegerolysins bind less specifically to sphingomyelin (SM) combined with cholesterol (Chol), which is a characteristic lipid mixture in vertebrate membranes. Fluorescently labelled aegerolysins can be used to study these lipids and lipid combinations similarly as antibodies are used to study the localisation or presence of proteins in cells. Although aegerolysins are non-toxic, they can form transmembrane cytolytic complexes in membranes containing aegerolysin the lipid receptor together with with MACPF-domain protein partners. In these two-component cytolytic complexes, component A (aegerolysin) recognises the lipid target, and component B (protein partner with the MACPF domain) enables the formation of the transmembrane pore.
We are currently investigating new fungal aegerolysins and their MACPF protein partners from the basidiomycetes Pleurotus pulmonarius, Heterobasidion irregulare, Trametes versicolor, Mucidula mucida and Lepista nuda. Here, we present the lipid binding affinities of these aegerolysins and their pore-forming activities when combined with their MACPF protein partners.