Antifungal Activity of NP20 Derived from Amphioxus Midkine/Pleiotrophin Homolog Against Aspergillus niger and Aspergillus fumigatus

With the emergence of antifungal resistance, systematic infections with Aspergillus are becoming the major cause of the clinical morbidity. The development of novel antifungal agents with high efficacy, low drug tolerance, and few side effects is urgent. In response to that need, we have identified NP20. Here we demonstrate clearly that NP20 has antifungal activity, capable of killing the spores of Aspergillus niger and Aspergillus fumigatus as well as causing direct damage to the surface, membrane, cytoplasm, organelle, and nucleus of the fungal spores. Interestingly, NP20 is active under temperature stress and a wide range of pH. Subsequently, MTT assay, assay for binding of NP20 to fungal cell wall components, membrane depolarization assay, confocal microscopy, ROS assay, DNA replication, and protein synthesis assay are performed to clarify the mechanisms underlying NP20 against Aspergillus. The results show that NP20 can bind with and pass through the fungal cell wall, and then interfere with the lipid membrane. Moreover, NP20 can induce intracellular ROS production, DNA fragmentation, and protein synthesis inhibition of the fungal cells. These together indicate that NP20 is a novel antifungal peptide, which has considerable potential for future development as novel peptide antibiotics against Aspergillus.