Studies on antifungal potential,primary characterization and mode of action of a de novo cytoplasmic protein (EAF) from human commensal Escherichia coli against Aspergillus spp.

A de novo protein named as eaf (escherichia antifungal protein) from the cytoplasmic pool of an escherichia coli strain (mtcc 1652),has been purified to homogeneity using anion exchange (q-xl sepharose) and cation exchange (sp-sepharose) chromatography. the mic (minimum inhibitory concentration) values of purified protein against a. fumigatus (the major pathogenic species) were found to be comparable with standard drugs i.e. 3.90 μg/ml,3.90 μg/ml and 1.25 μg/disc via microbroth dilution assay (mda),percentage spore germination inhibition (psgi) and disc diffusion assay (dda) respectively. toxicity results confirmed that it causes no haemolysis against human rbcs upto a concentration of 1000.0 μg/ml as compared to amphotericin b (conventional antifungal drug) that causes hundred percent haemolysis at a concentration of 37.50 μg/ml only.the purified protein demonstrated a molecular mass of 28 kda on sds-page which was further authenticated by maldi-tof. proteomic and bioinformatics studies deciphered its significant homology (72 %) with chain a-d-ribose binding protein (cluster 2 sugar binding periplasmic proteins; sequence homologues of transcription regulatory proteins) from e. coli. single dimensional page analysis of a. fumigatusproteins with due effect of eaf (at mic50) revealed the inhibition of two major proteins; a heat shock protein 70-hsp70 (68 kda); having role in protein folding and functioning andphenylanalyl-t rna synthetase podg subunit protein (74 kda); involved in growth polarity in fungi. scanning electron microscopic studies depicted homologous results. we suggest that eaf most likely belongs to a new group of proteins with potent antifungal characteristics,negligible toxicity and targeting vital proteins of fungal metabolism. © 2015 bentham science publishers.