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Structure and mode of action of a novel antibacterial peptide from the blood of Andrias davidianus
Author(s) -
Pei J.,
Chen D.,
Jin W.,
Geng J.,
Wang W.,
Zhang S.,
Yue T.,
Zhang H.
Publication year - 2019
Publication title -
letters in applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.698
H-Index - 110
eISSN - 1472-765X
pISSN - 0266-8254
DOI - 10.1111/lam.13219
Subject(s) - propidium iodide , bacteria , circular dichroism , chemistry , biophysics , random coil , antimicrobial peptides , peptide , mode of action , membrane , flow cytometry , aqueous solution , biochemistry , biology , microbiology and biotechnology , programmed cell death , apoptosis , organic chemistry , genetics
Abstract Andrias davidianus is widely recognized in traditional medicine as a cure‐all to treat a plethora of ailments. In a previous study, a novel antibacterial peptide named andricin B was isolated from A. davidianus blood. In this study, we investigated andricin B structure and its mode of action. Circular dichroism spectra suggested that andricin B adopts a random coil state in aqueous solution and a more rigid conformation in the presence of bacteria. Moreover propidium iodide/fluorescein diacetate double staining indicated that bacteria treated with andricin B were not immediately eliminated. Rather, there is a gradual bacterial death, followed by a sublethal stage. Scanning electronic microscope imaging indicates that andricin B might form pores on cell membranes, leading to the release of cytoplasmic contents. These results were consistent with flow cytometry analysis. Furthermore, Fourier transform infrared spectroscopy suggests that andricin B induces changes in the chemical properties in the areas surrounding these “pores” on the cell membranes. Significance and Impact of the Study The results of this study suggested the new perspectives about the mode of action of antimicrobial peptide (AMP) active against sensitive bacteria. The AMP was able to be in a random coiled state in aqueous solution but to change to a more rigid one in the presence of sensitive bacteria. Exposure to AMP might not lead to immediate death of treated bacteria, rather bacteria concentration decreased gradually flattening at a sublethal stage. These findings will help people to understand better how the AMPs activate against sensitive bacteria.