Addition of L-cysteine to the N- or C-terminus of the all-D-enantiomer [ D (KLAKLAK) 2 ] increases antimicrobial activities against multidrug-resistant Pseudomonas aeruginosa, Acinetobacter baumannii and Escherichia coli

PeerJ

article

Maki K. Ohno¹  Teruo Kirikae²  Eisaku Yoshihara³  Fumiko Kirikae²  Isao Ishida¹ 

[1]Faculty of Pharmaceutical Sciences, Teikyo Heisei University

[2]Department of Microbiology, Juntendo University School of Medicine

[3]Tokai University School of Medicine

关键词: Antimicrobial peptide;    Multidrug-resistant Gram-negative bacteria;   

DOI  :  10.7717/peerj.10176

学科分类：社会科学、人文和艺术（综合）

来源: Inra

【 摘 要 】

BackgroundAntimicrobial peptides have a broad spectrum of antimicrobial activities and are attracting attention as promising next-generation antibiotics against multidrug-resistant (MDR) bacteria. The all-d-enantiomer [D(KLAKLAK)2] has been reported to have antimicrobial activity against Escherichia coli and Pseudomonas aeruginosa, and to be resistant to protein degradation in bacteria because it is composed of D-enantiomer compounds. In this study, we demonstrated that modification of [D(KLAKLAK)2] by the addition of an L-cysteine residue to its N- or C- terminus markedly enhanced its antimicrobial activities against Gram-negative bacteria such as MDR Acinetobacter baumannii, E. coli, and P. aeruginosa.MethodsThe peptides [D(KLAKLAK)295% purity. The minimum inhibitory concentrations of peptides and antibiotics were determined by the broth microdilution method. The synergistic effects of the peptides and the antibiotics against MDR P. aeruginosa were evaluated using the checkerboard dilution method. In order to assess how these peptides affect the survival of human cells, cell viability was determined using a Cell Counting Kit-8.ResultsC-DP and DP-C enhanced the antimicrobial activities of the peptide against MDR Gram-negative bacteria, including A. baumannii, E. coli, and P. aeruginosa. The antimicrobial activity of DP-C was greater than that of C-DP, with these peptides also having antimicrobial activity against drug-susceptible P. aeruginosa and drug-resistant P. aeruginosa overexpressing the efflux pump components. C-DP and DP-C also showed antimicrobial activity against colistin-resistant E. coli harboring mcr-1, which encodes a lipid A modifying enzyme. DP-C showed synergistic antimicrobial activity against MDR P. aeruginosa when combined with colistin. The LD50 of DP-C against a human cell line HepG2 was six times higher than the MIC of DP-C against MDR P. aeruginosa. The LD50 of DP-C was not altered by incubation with low-dose colistin.ConclusionAttachment of an L-cysteine residue to the N- or C-terminus of [D(KLAKLAK)2] enhanced its antimicrobial activity against A. baumannii, E. coli, and P. aeruginosa. The combination of C-DP or DP-C and colistin had synergistic effects against MDR P. aeruginosa. In addition, DP-C and C-DP showed much stronger antimicrobial activity against MDR A. baumannii and E. coli than against P. aeruginosa.

【 授权许可】

CC BY