Most antimicrobial peptides (AMPs) impair the viability of target bacteria by permeabilizing bacterial
membranes. However, the proline-rich AMPs have been shown to kill susceptible organisms without causing
significant membrane perturbation and may act by inhibiting the activity of bacterial targets. To gain initial
insight into the events that follow interaction of a proline-rich peptide with bacterial cells, we used DNA
macroarray technology to monitor transcriptional alterations of Escherichia coli in response to challenge with
a subinhibitory concentration of the proline-rich Bac7(1-35). Substantial changes in the expression levels of 70
bacterial genes from various functional categories were detected. Among these, 26 genes showed decreased
expression, while 44 genes, including genes that are potentially involved in bacterial resistance to antimicrobials,
showed increased expression. The generation of a transcriptional response under the experimental
conditions used is consistent with the ability of Bac7(1-35) to interact with bacterial components and affect
biological processes in this organism.
