Antibacterial and cell penetrating-effects of LFcin17-30, LFampin265-284 and LFchimera on enteroaggregative Escherichia coli

Lactoferrin (LF) is a protein with antimicrobial activity, which is conferred in part by two regions contained in its N-terminal lobe. These regions have been used to develop the following synthetic peptides: Lactoferricin17-30, Lactoferrampin265-284 and LFchimera (a fusion of Lactoferricin17-30 and Lactoferrampin265-284). We have reported that these LFpeptides have antibacterial activity against several pathogenic bacteria; however, the exact mechanism of action has not been established. Here, we report the effects of LFpeptides on the viability of enteroaggregative Escherichia coli (EAEC) and the ability of these peptides to penetrate into the bacteria cytoplasm. Materials and Methods: The viability of EAEC treated with LFpeptides was determined via enumeration of colony-forming units, and the binding and internalization of the LFpeptides was followed via immunogold labeling and electron microscopy. Results: Treatment of EAEC with 20 and 40 ÂľM LFpeptides reduced bacterial growth compared to untreated bacteria. Initially the peptides associated with the plasma membrane, but after 5 to 30 min of incubation, the peptides were found in the cytoplasm. Remarkably, bacteria treated with LFchimera developed cytosolic electrondense structures that contained the antimicrobial peptide. Our results suggest that the antibacterial mechanism of LFpeptides on EAEC involves their interaction with and penetration into the bacteria.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author