Conjugation of Cell-Penetrating Peptides to Antimicrobial Peptides Enhances Antibacterial Activity

Hyunhee Lee; Sung In Lim; Sung-Heui Shin; Yong Lim; Jae Woong Koh; Sungtae Yang

doi:10.1021/acsomega.9b02278

Conjugation of Cell-Penetrating Peptides to Antimicrobial Peptides Enhances Antibacterial Activity

ACS Omega. 2019 Sep 9;4(13):15694-15701. doi: 10.1021/acsomega.9b02278. eCollection 2019 Sep 24.

Authors

Hyunhee Lee¹, Sung In Lim², Sung-Heui Shin^{1

3}, Yong Lim^{1

3}, Jae Woong Koh³, Sungtae Yang^{1

3}

Affiliations

¹ Department of Biomedical Science, Graduate School, Chosun University, Gwangju 61452, South Korea.
² Department of Chemical Engineering, Pukyong National University, Busan 48513, South Korea.
³ Department of Microbiology, Department of Immunology, and Department of Ophthalmology, Chosun University College of Medicine, Gwangju 61452, South Korea.

Abstract

Antimicrobial peptides (AMPs), essential elements in host innate immune defenses against numerous pathogens, have received considerable attention as potential alternatives to conventional antibiotics. Most AMPs exert broad-spectrum antimicrobial activity through depolarization and permeabilization of the bacterial cytoplasmic membrane. Here, we introduce a new approach for enhancing the antibiotic activity of AMPs by conjugation of a cationic cell-penetrating peptide (CPP). Interestingly, CPP-conjugated AMPs elicited only a 2- to 4-fold increase in antimicrobial activity against Gram-positive bacteria, but showed a 4- to 16-fold increase in antimicrobial activity against Gram-negative bacteria. Although CPP-AMP conjugates did not significantly increase membrane permeability, they efficiently translocated across a lipid bilayer. Indeed, confocal microscopy showed that, while AMPs were localized mainly in the membrane of Escherichia coli, the conjugates readily penetrated bacterial cells. In addition, the conjugates exhibited a higher affinity for DNA than unconjugated AMPs. Collectively, we demonstrate that CPP-AMP conjugates possess multiple functional properties, including membrane permeabilization, membrane translocation, and DNA binding, which are involved in their enhanced antibacterial activity against Gram-negative bacteria. We propose that conjugation of CPPs to AMPs may present an effective approach for the development of novel antimicrobials against Gram-negative bacteria.