Oligomerization and insertion of antimicrobial peptide TP4 on bacterial membrane and membrane-mimicking surfactant sarkosyl

• Published in: PloS one 2019-05, Vol.14 (5), p.e0216946-e0216946
• Main Authors: Wang, Shih-Han, Wang, Chiu-Feng, Chang, Ting-Wei, Wang, Yu-June, Liao, You-Di
• Format: Article
• Language: English
• Subjects: Animals; Anti-Bacterial Agents - chemistry; Anti-Bacterial Agents - isolation & purification; Anti-Bacterial Agents - pharmacology; Antibiotics; Antiinfectives and antibacterials; Antimicrobial agents; Antimicrobial Cationic Peptides - chemistry; Antimicrobial Cationic Peptides - isolation & purification; Antimicrobial Cationic Peptides - pharmacology; Antimicrobial peptides; Bacteria; Biological Transport; Biology and Life Sciences; Cell Membrane - drug effects; Cell Membrane - metabolism; Cell Membrane Permeability - drug effects; Cellulose; Cichlids - physiology; Cytosol; Drug resistance; E coli; Escherichia coli; Escherichia coli - drug effects; Escherichia coli - metabolism; Fish Proteins - chemistry; Fish Proteins - isolation & purification; Fish Proteins - pharmacology; Fluorescent Dyes - metabolism; Genetic aspects; Glutaraldehyde; Hydrophobic and Hydrophilic Interactions; Hydrophobicity; Insertion; Membrane permeability; Membranes; Microorganisms; Mimicry; Morphology; Oligomerization; Oligomers; Organic Chemicals - metabolism; Peptides; Permeability; Physical Sciences; Polymer crosslinking; Protein Binding; Protein Multimerization; Proteins; Research and Analysis Methods; Sarcosine - analogs & derivatives; Sarcosine - pharmacology; Solubility; Static Electricity; Surface active agents; Surface-Active Agents - pharmacology; Surfactants; Tilapia; Trifluoroethanol; Trifluoroethanol - pharmacology
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0216946

Antimicrobial peptides (AMPs) are important components of the host innate defense mechanism against invading microorganisms. Although AMPs are known to act on bacterial membranes and increase membrane permeability, the action mechanism of most AMPs still remains unclear. In this report, we found that the TP4 peptides from Nile tilapia anchored on E. coli cells and enabled them permeable to SYTOX Green in few minutes after TP4 addition. TP4 peptides existed in small dots either on live or glutaraldehyde-fixed cells. TP4 peptides were driven into oligomers either in soluble or insoluble form by a membrane-mimicking anionic surfactant, sarkosyl, depending on the concentrations employed. The binding forces among TP4 components were mediated through hydrophobic interaction. The soluble oligomers were negatively charged on surface, while the insoluble oligomers could be fused with each other or piled on existing particles to form larger particles with diameters 0.1 to 20 μm by hydrophobic interactions. Interestingly, the morphology and solubility of TP4 particles changed with the concentration of exogenous sarkosyl or trifluoroethanol. The TP4 peptides were assembled into oligomers on or in bacterial membrane. This study provides direct evidence and a model for the oligomerization and insertion of AMPs into bacterial membrane before entering into cytosol.