An antifungal protein from Escherichia coli

Abstract

A cytosolic protein was purified from Escherichia coli BL21 that demonstrated potent antifungal activity against pathogenic strains of Aspergillus fumigatus, Aspergillus flavus, Aspergillus niger and Candida albicans. The MIC of purified protein from E. coli BL21 (PPEBL21) against Aspergillus species and C. albicans was 1.95-3.98 and 15.62 microg ml(-1), respectively. In vitro toxicity tests demonstrated no cytotoxicity of PPEBL21 to human erythrocytes up to the tested concentrations of 1250 microg ml(-1). Amphotericin B was lethal to 100 % of human erythrocytes at a concentration of 37.5 microg ml(-1). The N-terminal amino acid sequence of PPEBL21 was found to be DLAEVASR, which showed 75 % sequence similarity with alcohol dehydrogenase of yeast. Mass fingerprinting by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry also substantiated these observations. The results suggested that E. coli BL21 might be an important bioresource of lead molecules for developing new peptide-based therapies for treating fungal infections.