Abstract

BackgroundNP4P 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).ResultsIn 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 Staphylococcus aureus), 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 S. aureus membranes with enhanced efficacy in the presence of NP4P.ConclusionsNP4P selectively enhanced the bactericidal activities of membrane-disrupting antimicrobial peptides by increasing the efficacy of membrane disruption against the cytoplasmic membrane.

Highlights

  • IntroductionNP4P 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)

  • NP4P is a synthetic peptide derived from a natural, non-antimicrobial peptide fragment by substitution of all acidic amino acid residues with amides (i.e., Glu ® Gln, and Asp ® Asn)

  • Enhancer activity for antimicrobial peptides The parent peptide P4P inhibited the bactericidal activity of cecropin P4 and some other antimicrobial peptides

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Summary

Introduction

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). Antimicrobial peptides (AMPs) are peptides that are selectively toxic against microbes. More than 800 AMPs have been discovered in various organisms including vertebrates, invertebrates, plants, protozoans, and microbes. The structures of AMPs are extremely diverse. They are categorized into distinct structural groups such as amphipathic a-helical peptides, and bsheet peptides stabilized by intramolecular disulfide bridges [1]. Several AMPs are already in practical use. Many AMPs have been investigated for practical use [4]. Microbial killing by AMPs is often correlated mainly with membrane disruption some other intracelluar and extracellular mechanisms contribute to overall activity [1]

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