Fungicidal properties, sterol binding, and proteolytic resistance of the synthetic peptide D4E1

Abstract

The fungicidal properties of the synthetic peptide D4E1 were studied with nongerminated and germinating conidia of Aspergillus flavus, Aspergillus fumigatus, Aspergillus niger, Fusarium moniliforme, and Fusarium oxysporum. The minimal lethal concentrations (MLC) needed to kill 100% of germinating conidia ofA. fumigatus, A. flavus, and A. niger were 12.5, 12.5, and 25 µM, respectively. The MLC value for nongerminated and germinating conidia of both Fusarium spp. was 3.0 µM. Except for A. fumigatus, D4E1 was inactive against the nongerminated conidia of the Aspergillus spp. Physicochemical studies showed D4E1 complexed with ergosterol, a sterol present in conidial walls. Cholesterol, present in nongerminated conidia of F. moniliforme, had a greater affinity for D4E1 than did ergosterol. D4E1 was more resistant to fungal and plant protease degradation than the natural peptide, cecropin A. These in vitro results suggest D4E1 is a candidate for transgenic expression in plants to enhance host resistance to fungal infection.Key words: peptides, fungicidal, Aspergillus spp., Fusarium spp., sterols.