Skip to Content
Merck
  • Cationic amphipathic peptides KT2 and RT2 are taken up into bacterial cells and kill planktonic and biofilm bacteria.

Cationic amphipathic peptides KT2 and RT2 are taken up into bacterial cells and kill planktonic and biofilm bacteria.

Biochimica et biophysica acta (2015-03-15)
Thitiporn Anunthawan, César de la Fuente-Núñez, Robert E W Hancock, Sompong Klaynongsruang
ABSTRACT

We investigated the mechanisms of two tryptophan-rich antibacterial peptides (KT2 and RT2) obtained in a previous optimization screen for increased killing of both Gram-negative and Gram-positive bacteria pathogens. At their minimal inhibitory concentrations (MICs), these peptides completely killed cells of multidrug-resistant, enterohemorrhagic pathogen Escherichia coli O157:H7 within 1-5 min. In addition, both peptides exhibited anti-biofilm activity at sub-MIC levels. Indeed, these peptides prevented biofilm formation and triggered killing of cells in mature E. coli O157:H7 biofilms at 1 μM. Both peptides bound to bacterial surface LPS as assessed using the dansyl-polymyxin displacement assay, and were able to interact with the lipids of liposomes as determined by observing a tryptophan blue shift. Interestingly, even though these peptides were highly antimicrobial, they did not induce pore formation or aggregates in bacterial cell membranes. Instead these peptides readily penetrated into bacterial cells as determined by confocal microscopy of labeled peptides. DNA binding assays indicated that both peptides bound to DNA with higher affinity than the positive control peptide buforin II. We propose that cationic peptides KT2 and RT2 bind to negatively-charged LPS to enable self-promoted uptake and, subsequently interact with cytoplasmic membrane phospholipids through their hydrophobic domains enabling translocation across the bacterial membrane and entry into cells within minutes and binding to DNA and other cytoplasmic membrane. Due to their dual antimicrobial and anti-biofilm activities, these peptides may find use as an alternative to (or in conjunction with) conventional antibiotics to treat acute infections caused by planktonic bacteria and chronic, biofilm-related infections.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Phenol, BioUltra, for molecular biology, TE-saturated, ~73% (T)
Sigma-Aldrich
Phenol, unstabilized, purified by redistillation, ≥99%
Sigma-Aldrich
Phenol, unstabilized, ReagentPlus®, ≥99%
Sigma-Aldrich
Phenol, ≥99%
Sigma-Aldrich
Phenol, contains hypophosphorous as stabilizer, loose crystals, ACS reagent, ≥99.0%
Sigma-Aldrich
Phenol, puriss., meets analytical specification of Ph. Eur., BP, USP, 99.5-100.5% (GC)
Sigma-Aldrich
Phenol, puriss., meets analytical specification of Ph. Eur., BP, USP, ≥99.5% (GC), crystalline (detached)
Sigma-Aldrich
8-Aminonaphthalene-1,3,6-trisulfonic acid disodium salt, BioReagent, suitable for fluorescence, ≥90% (CE)
Sigma-Aldrich
Phenol, ≥96.0% (calc. on dry substance, T)
Sigma-Aldrich
p-Xylene-bis(N-pyridinium bromide), ≥95% (TLC)
Sigma-Aldrich
Phenol solution, BioReagent, Saturated with 0.01 M citrate buffer, pH 4.3 ± 0.2, for molecular biology
Sigma-Aldrich
Phenol, for molecular biology
Sigma-Aldrich
1,2-Dioleoyl-sn-glycero-3-phosphocholine, lyophilized powder
Sigma-Aldrich
Phenol, BioXtra, ≥99.5% (GC)
Sigma-Aldrich
Liquified Phenol, ≥89.0%
Sigma-Aldrich
Phenol solution, Equilibrated with 10 mM Tris HCl, pH 8.0, 1 mM EDTA, BioReagent, for molecular biology
Sigma-Aldrich
Phenol, puriss. p.a., ACS reagent, reag. Ph. Eur., 99.0-100.5%
Sigma-Aldrich
Phenol, natural, 97%, FG
Sigma-Aldrich
DL-Tryptophan, ≥99% (HPLC)
Sigma-Aldrich
DL-Tryptophan, ≥99% (HPLC)