Functional studies of nigerolysins in Aspergillus niger

Author:

Nada Kraševec 1, Maruša Novak 2, Urška Čepin 3,4, Vesna Hodnik 2, Mojca Narat 5,
Maja Jamnik 1, Gregor Anderluh 1, Kristina Sepčić 2

Author address:

1 Department of Molecular Biology and Nanobiotechnology, National Institute of Chemistry, Ljubljana, Slovenia;
2 Department of Biology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia;
3 BioSistemika Ltd, Ljubljana, Slovenia;
4 National Institute of Biology, Ljubljana, Slovenia;
5 Department of Animal Science, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia

Full conference title:

15th European Conference on Fungal Genetics 2020

Date: 21 June 2020

Abstract:

Proteins of the aegerolysin family have a high abundance in Fungi. Due to their specific binding to membrane lipids, and their membrane-permeabilization potential in concert with protein partners belonging to a membrane-attack-complex/perforin (MACPF) superfamily, they were proposed as useful tools in different biotechnological and biomedical applications (1).

We performed functional studies on expression of the genes encoding aegerolysin and MACPF-like proteins in A. niger (2). Following the naming of these proteins in Pleurotus sp, these predicted homologues have been named as Nigerolysins (Nig), adding A and a number (1 or 2) for aegerolysins and B and a number (1 or 2) for MACPF-like proteins. Results suggest the sporulation process being crucial for strong induction of the expression of all these genes. However, deletion of either of the nigerolysin A genes did not influence the growth, development, sporulation efficiency and phenotype of the mutants, indicating that nigerolysins A are not key factors in the sporulation process. In all expression studies we noticed a strong correlation in the expression of one of the nigerolysins A and one of the nigerolysins B gene. Nigerolysins A were confirmed to be secreted from the fungus. We also showed the specific interaction of a recombinant A. niger nigerolysin A with an invertebrate-specific membrane sphingolipid. Moreover, using this protein labelled with mCherry we successfully stained insect cells membranes containing this particular sphingolipid.

Our results suggest, that nigerolysins A in this species, and probably also in other aspergilli, could be involved in defence against predators.

1. Novak, Kraševec, Skočaj, Maček, Anderluh, Sepčić. Fungal aegerolysin-like proteins: distribution, activities, and applications. Appl microbiol biotechnol 2015

2. Novak, Čepin, Hodnik, Narat, Jamnik, Kraševec, Sepčić, Anderluh. Functional studies of aegerolysin and MACPF-like proteins in Aspergillus niger. Mol microbiol 2019

Link to conference website:

Link Conference abstract:

ECFG 15