An enhancer peptide for membrane-disrupting antimicrobial peptides

<p>Abstract</p> <p>Background</p> <p>NP4P is a synthetic peptide derived from a natural, non-antimicrobial peptide fragment (pro-region of nematode cecropin P4) by substitution of all acidic amino acid residues with amides (i.e., Glu → Gln, and Asp → Asn).</p> <p>Results</p> <p>In the presence of NP4P, some membrane-disrupting antimicrobial peptides (ASABF-α, polymyxin B, and nisin) killed microbes at lower concentration (e.g., 10 times lower minimum bactericidal concentration for ASABF-α against <it>Staphylococcus aureus</it>), whereas NP4P itself was not bactericidal and did not interfere with bacterial growth at ≤ 300 μg/mL. In contrast, the activities of antimicrobial agents with a distinct mode of action (indolicidin, ampicillin, kanamycin, and enrofloxacin) were unaffected. Although the membrane-disrupting activity of NP4P was slight or undetectable, ASABF-α permeabilized <it>S. aureus </it>membranes with enhanced efficacy in the presence of NP4P.</p> <p>Conclusions</p> <p>NP4P selectively enhanced the bactericidal activities of membrane-disrupting antimicrobial peptides by increasing the efficacy of membrane disruption against the cytoplasmic membrane.</p