Antimicrobial Peptides from the Aurein Family Form Ion‐Selective Pores in Bacillus subtilis

Abstract

The mechanism of action of aurein 2.2 and aurein 2.3, antimicrobial peptides from the frog Litoria aurea, was investigated. Proteomic profiling of the Bacillus subtilis stress response indicates that the cell envelope is the main target for both aureins. Upon treatment, the cytoplasmic membrane depolarizes and cellular ATP levels decrease. Global element analysis shows that intracellular concentrations of certain metal ions (potassium, magnesium, iron, and manganese) strongly decrease. Selective translocation of some ions over others was demonstrated in vitro. The same set of ions also leaks from B. subtilis cells treated with sublethal concentrations of gramicidin S, MP196, and nisin. Aureins do not permeabilize the cell membrane for propidium iodide thus excluding formation of large, unspecific pores. Our data suggest that the aureins acts by forming small pores thereby causing membrane depolarization, and by triggering the release of certain metal ions thus disturbing cellular ion homeostasis.

Daptomycin inhibits cell envelope synthesis by interfering with fluid membrane microdomains

“…This finding is in sharp contrast to the leakage of potassium caused by the specific potassium ionophore valinomycin ( Fig. 2A) and the leakage of potassium, magnesium, iron, and manganese observed with the membranedisrupting peptide gramicidin S (32).…”

Alignment‐based design and synthesis of new antimicrobial Aurein‐derived peptides with improved activity against Gram‐negative bacteria and evaluation of their toxicity on human cells

“…In AureinN1 and N2, GKLR sequence is a high‐frequency segment in peptides used against Gram‐negative bacteria and was added to C terminal region. Although GLFD sequence is highly conserved in Aurein family (Wenzel et al, ), according to the basic concepts in AMPs design, the anionic aspartic acid can decrease the antimicrobial properties. Therefore, D was replaced with asparagine (N) and tryptophan (W) in AureinN1 and AureinN2, respectively.…”

“…So far, 17 Aurein peptides have been identified in the secretion of L. aurea and 16 peptides from the corresponding secretion of L. raniformis (Rozek1 et al, ). Aureins have suitable antibacterial activity against Gram‐positive bacteria and moderate or weak antimicrobial activity against Gram‐negative bacteria (Wenzel et al, ). To date, many AMPs in clinical trials have been ineffective due to some limitations disrupting their therapeutic application.…”

Structure and membrane interactions of the homodimeric antibiotic peptide homotarsinin

“…Hundreds of naturally occurring antimicrobial peptides differing in length, amino acid composition, primary structure, hydrophobicity, amphipathicity and membrane-bound conformation have been isolated from amphibians9101112. They have been classified for shared properties that appear to be important for their structure and activity such as their cationic amphipathic character, regions rich in hydrophobic and aromatic residues1314 or intra-chain cystine bonds as described for defensins15 and protegrins16.…”