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Adaptive and Mutational Responses to Peptide Dendrimer Antimicrobials in Pseudomonas aeruginosa

Type of publication Peer-reviewed
Publikationsform Original article (peer-reviewed)
Author Ben Jeddou Fatma, Falconnet Léna, Luscher Alexandre, Siriwardena Thissa, Reymond Jean-Louis, van Delden Christian, Köhler Thilo,
Project Antimicrobial peptide dendrimers (AMPD) and bicyclic peptides (AMBP) as therapeutic agents against multidrug resistant bacteria
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Original article (peer-reviewed)

Journal Antimicrobial Agents and Chemotherapy
Volume (Issue) 64(4)
Page(s) 1 - 14
Title of proceedings Antimicrobial Agents and Chemotherapy
DOI 10.1128/aac.02040-19

Open Access

URL http://doi.org/10.1128/AAC.02040-19
Type of Open Access Publisher (Gold Open Access)

Abstract

ABSTRACT Colistin (polymyxin E) is a last-resort antibiotic against multidrug-resistant isolates of Pseudomonas aeruginosa . However, the nephro-toxicity of colistin limits its use, spurring the interest in novel antimicrobial peptides (AMP). Here, we show that the synthetic AMP-dendrimer G3KL (MW 4,531.38 Da, 15 positive charges, MIC = 8 mg/liter) showed faster killing than polymyxin B (Pmx-B) with no detectable resistance selection in P. aeruginosa strain PA14. Spontaneous mutants selected on Pmx-B, harboring loss of function mutations in the PhoQ sensor kinase gene, showed increased Pmx-B MICs and arnB operon expression (4-amino- l -arabinose addition to lipid A), but remained susceptible to dendrimers. Two mutants carrying a missense mutation in the periplasmic loop of the PmrB sensor kinase showed increased MICs for Pmx-B (8-fold) and G3KL (4-fold) but not for the dendrimer T7 (MW 4,885.64 Da, 16 positive charges, MIC = 8 mg/liter). The pmrB mutants showed increased expression of the arnB operon as well as of the speD2-speE2 -PA4775 operon, located upstream of pmrAB , and involved in polyamine biosynthesis. Exogenous supplementation with the polyamines spermine and norspermine increased G3KL and T7 MICs in a phoQ mutant background but not in the PA14 wild type. This suggests that both addition of 4-amino- l -arabinose and secretion of polyamines are required to reduce susceptibility to dendrimers, probably neutralizing the negative charges present on the lipid A and the 2-keto-3-deoxyoctulosonic acid (KDO) sugars of the lipopolysaccharide (LPS), respectively. We further show by transcriptome analysis that the dendrimers G3KL and T7 induce adaptive responses through the CprRS two-component system in PA14.
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