Transcriptional Profile of theEscherichia coliResponse to the Antimicrobial Insect Peptide Cecropin A

Abstract

Cationic antimicrobial peptides are believed to exert their primary activities on anionic bacterial cell membranes; however, this model does not adequately account for several important structure-activity relationships. These relationships are likely to be influenced by the bacterial response to peptide challenge. In order to characterize the genomic aspect of this response, transcription profiles were examined for Escherichia coli isolates treated with sublethal and lethal concentrations of the cationic antimicrobial peptide cecropin A. Transcript levels for 26 genes changed significantly following treatment with sublethal peptide concentrations, and half of the transcripts corresponded to protein products with unknown function. The pattern of response is distinct from that following treatment with lethal concentrations and is also distinct from the bacterial response to nutritional, thermal, osmotic, or oxidative stress. These results demonstrate that cecropin A induces a genomic response in E. coli apart from any lethal effects on the membrane and suggest that a complete understanding of its mechanism of action may require a detailed examination of this response.

Antimicrobial peptides: A natural alternative to chemical antibiotics and a potential for applied biotechnology

“…It is thought that cationic peptides might induce genomic responses in bacteria treated with AMPs, in addition to any lethal effect on the bacterial membrane. This appears to be the case, as recently demonstrated (Hong et al 2003). These authors have shown that the transcription profiles of at least 26 Escherichia coli genes change specifically and significantly after exposure to lethal and sub lethal concentrations of Cecropin A, an emblematic cationic peptide.…”

Antibiotic dialogues: induction of silent biosynthetic gene clusters by exogenous small molecules

“…For example, results by Davies (Goh et al 2002) have shown that erythromycin-mediated transcriptional modulation occurred to the same extent in both wt and mutants defective in a variety of stress response pathways. Hu et al reached a similar conclusion when examining the transcriptional changes induced by the antibiotic cecropin in E. coli O157 (Hong et al 2003).…”

A Synergism between Temporins toward Gram-negative Bacteria Overcomes Resistance Imposed by the Lipopolysaccharide Protective Layer

“…These properties allow many of them to initially bind the negatively charged microbial membrane and alter its integrity, leading to cell death (9,11,12). However, a few AMPs have been shown to have additional/alternative intracellular targets besides the cytoplasmic membrane (13)(14)(15)(16)(17)(18). Interestingly, several kinds of plants and animals can synthesize a considerable number of AMPs with relatively minor sequences and structural differences among them.…”