Antifungal mechanism of antifungal peptide derived from cecropin A(1- 8)-melittin(1-12) hybrid against Aspergillus fumigatus

The antifungal mechanism of the antifungal peptide against Aspergillus fumigatus, K^{18, 19}CA-(1-8)-ME(1-12), derived from cecropin A(1-8)- melittin(1-12) was investigated by confocal laser scanning microscopy, cell wall regeneration, ATPase activity inhibition, and released potassium ion. By confocal laser scanning microscopy, K^{18, 19}-CA(1-8)-ME(1-12) was detected on the surface of A. fumigatus, while cecropin A used as a negative control peptide was not detected. The protoplast of A. fumigatus treated with K^{18, 19}-CA(1-8)-ME(1-12) failed to regenerate the fungal cell walls. Compared with cecropin A, the amount of potassium ion released by K^{18, 19}-CA(1-8)-ME(1-12) was increased. Furthermore, K^{18, 19}-CA(1-8)-ME(1- 12) inhibited the ATPase activity on the plasma membrane. These results suggested that K^{18, 19}-CA(1-8)-ME (1-12) acts on the plasma membrane of A. fumigatus and its antifungal action is due to the ion channel or pore formation on the plasma membrane.