Work

Single-cell, real-time detection of oxidative stress induced in Escherichia coli by the antimicrobial peptide CM15

Year: 2015

Type: article

Abstract: Antibiotics target specific biochemical mechanisms in bacteria. In response to new drugs, pathogenic bacteria rapidly develop resistance. In contrast, antimicrobial peptides (AMPs) have retained broad spectrum antibacterial potency over millions of years. We present single-cell fluorescence assays that detect reactive oxygen species (ROS) in the Escherichia coli cytoplasm in real time. Within 30 s of permeabilization of the cytoplasmic membrane by the cationic AMP CM15 [combining residues 1-7 of cecropin A (from moth) with residues 2-9 of melittin (bee venom)], three fluorescence signals report oxidative stress in the cytoplasm, apparently involving O2 (-), H2O2, and •OH. Mechanistic studies indicate that active respiration is a prerequisite to the CM15-induced oxidative damage. In anaerobic conditions, signals from ROS are greatly diminished and the minimum inhibitory concentration increases 20-fold. Evidently the natural human AMP LL-37 also induces a burst of ROS. Oxidative stress may prove a significant bacteriostatic mechanism for a variety of cationic AMPs. If so, host organisms may use the local oxygen level to modulate AMP potency.

Source: Proceedings of the National Academy of Sciences

DOI: 10.1073/pnas.1417703112

Authors: Heejun Choi, Zhilin Yang, James C. Weisshaar

Institution: University of Wisconsin–Madison

Language: English

Topic: Antimicrobial Peptides and Activities

Subfield: Microbiology

Field: Immunology and Microbiology

Domain: Life Sciences

SDG: Good health and well-being

Open Access status: bronze

Funders: University of Wisconsin-Madison, National Institutes of Health, University of Illinois at Urbana-Champaign, National Institute of General Medical Sciences