Revealing the Mechanisms of Synergistic Action of Two Magainin Antimicrobial Peptides

The study of peptide-lipid and peptide-peptide interactions as well as their topology and dynamics using biophysical and structural approaches have changed our view how antimicrobial peptides work and function. It has become obvious that both the peptides and the lipids arrange in soft supramolecular arrangements which are highly dynamic and able to change and mutually adapt their conformation, membrane penetration, and detailed morphology. This can occur on a local and a global level. This review focuses on cationic amphipathic peptides of the magainin family which were studied extensively by biophysical approaches. They are found intercalated at the membrane interface where they cause membrane thinning and ultimately lysis. Interestingly, mixtures of two of those peptides namely magainin 2 and PGLa which occur naturally as a cocktail in the frog skin exhibit synergistic enhancement of antimicrobial activities when investigated together in antimicrobial assays but also in biophysical experiments with model membranes. Detailed dose-response curves, presented here for the first time, show a cooperative behavior for the individual peptides which is much increased when PGLa and magainin are added as equimolar mixture. This has important consequences for their bacterial killing activities and resistance development. In membranes that carry unsaturations both peptides align parallel to the membrane surface where they have been shown to arrange into mesophases involving the peptides and the lipids. This supramolecular structuration comes along with much-increased membrane affinities for the peptide mixture. Because this synergism is most pronounced in membranes representing the bacterial lipid composition it can potentially be used to increase the therapeutic window of pharmaceutical formulations.

Download Full-text

Interaction of the Gelsolin-Derived Antibacterial PBP 10 Peptide with Lipid Bilayers and Cell Membranes

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00134-06 ◽

2006 ◽

Vol 50 (9) ◽

pp. 2932-2940 ◽

Cited By ~ 36

Author(s):

Robert Bucki ◽

Paul A. Janmey

Keyword(s):

Antimicrobial Peptides ◽

Lipid Bilayers ◽

Cell Membranes ◽

Plasma Membranes ◽

Antimicrobial Activities ◽

Eukaryotic Cells ◽

Hypotonic Solution ◽

Antibacterial Peptides ◽

Bacterial Killing ◽

Bacterial Membranes

ABSTRACTPBP 10, an antibacterial, cell membrane-permeant rhodamine B-conjugated peptide derived from the polyphosphoinositide binding site of gelsolin, interacts selectively with both lipopolysaccharides (LPS) and lipoteichoic acid (LTA), the distinct components of gram-negative and gram-positive bacteria, respectively. Isolated LPS and LTA decrease the antimicrobial activities of PBP 10, as well as other antimicrobial peptides, such as cathelicidin-LL37 (LL37) and mellitin. In an effort to elucidate the mechanism of bacterial killing by PBP 10, we compared its effects on artificial lipid bilayers and eukaryotic cell membranes with the actions of the mellitin, magainin II, and LL37 peptides. This study reveals that pore formation is unlikely to be involved in PBP 10-mediated membrane destabilization. We also investigated the effects of these peptides on platelets and red blood cells (RBCs). Comparison of these antimicrobial peptides shows that only mellitin has a toxic effect on platelets and RBCs in a concentration range concomitant with its bactericidal activity. The hemolytic activities of the PBP 10 and LL37 peptides significantly increase when RBCs are osmotically swollen in hypotonic solution, indicating that these antibacterial peptides may take advantage of the more extended form of bacterial membranes in exerting their killing activities. Additionally, we found that LL37 hemolytic activity was much higher when RBCs were induced to expose phosphatidylserine to the external leaflet of their plasma membranes. This finding suggests that asymmetrical distribution of phospholipids in the external membranes of eukaryotic cells may represent an important factor in determining the specificity of antibacterial peptides for targeting bacteria rather than eukaryotic cells.

Download Full-text

Plant antimicrobial peptides: structures, functions, and applications

Botanical Studies ◽

10.1186/s40529-021-00312-x ◽

2021 ◽

Vol 62 (1) ◽

Author(s):

Junpeng Li ◽

Shuping Hu ◽

Wei Jian ◽

Chengjian Xie ◽

Xingyong Yang

Keyword(s):

Antimicrobial Activity ◽

Antimicrobial Peptides ◽

Agricultural Production ◽

Food Additives ◽

Antimicrobial Activities ◽

Gram Positive Bacteria ◽

Potential Applications ◽

Potential Applicability ◽

Bacteria And Fungi ◽

Positively Charged

AbstractAntimicrobial peptides (AMPs) are a class of short, usually positively charged polypeptides that exist in humans, animals, and plants. Considering the increasing number of drug-resistant pathogens, the antimicrobial activity of AMPs has attracted much attention. AMPs with broad-spectrum antimicrobial activity against many gram-positive bacteria, gram-negative bacteria, and fungi are an important defensive barrier against pathogens for many organisms. With continuing research, many other physiological functions of plant AMPs have been found in addition to their antimicrobial roles, such as regulating plant growth and development and treating many diseases with high efficacy. The potential applicability of plant AMPs in agricultural production, as food additives and disease treatments, has garnered much interest. This review focuses on the types of plant AMPs, their mechanisms of action, the parameters affecting the antimicrobial activities of AMPs, and their potential applications in agricultural production, the food industry, breeding industry, and medical field.

Download Full-text

Vibrating Mesh Nebulisation of Pro-Antimicrobial Peptides for Use in Cystic Fibrosis

Pharmaceutics ◽

10.3390/pharmaceutics11050239 ◽

2019 ◽

Vol 11 (5) ◽

pp. 239 ◽

Cited By ~ 3

Author(s):

Éanna Forde ◽

Graeme Kelly ◽

Louise Sweeney ◽

Deirdre Fitzgerald-Hughes ◽

Ronan MacLoughlin ◽

...

Keyword(s):

Cystic Fibrosis ◽

Antimicrobial Peptides ◽

Droplet Size ◽

Droplet Size Distribution ◽

Antimicrobial Activities ◽

Physical Characteristics ◽

Mechanically Ventilated ◽

Delivery Times ◽

Before And After ◽

Spontaneously Breathing

Background: There has been considerable interest in the use of antimicrobial peptides (AMPs) as antimicrobial therapeutics in many conditions including cystic fibrosis (CF). The aim of this study is to determine if the prodrugs of AMPs (pro-AMPs) can be delivered to the lung by a vibrating mesh nebuliser (VMN) and whether the pro-AMP modification has any effect on delivery. Methods: Physical characteristics of the peptides (AMP and pro-AMP) and antimicrobial activity were compared before and after nebulisation. Droplet size distribution was determined by laser diffraction and cascade impaction. Delivery to a model lung was determined in models of spontaneously-breathing and mechanically-ventilated patients. Results: The physical characteristics and antimicrobial activities were unchanged after nebulisation. Mean droplet size diameters were below 5 μm in both determinations, with the fine particle fraction approximately 67% for both peptides. Approximately 25% of the nominal dose was delivered in the spontaneously-breathing model for both peptides, with higher deliveries observed in the mechanically-ventilated model. Delivery times were approximately 170 s per mL for both peptides and the residual volume in the nebuliser was below 10% in nearly all cases. Conclusions: These results demonstrate that the delivery of (pro-)AMPs to the lung using a VMN is feasible and that the prodrug modification is not detrimental. They support the further development of pro-AMPs as therapeutics in CF.

Download Full-text

Antimicrobial peptides in silkworm

Animal Biology ◽

10.1163/15707563-20191065 ◽

2019 ◽

Vol 69 (4) ◽

pp. 391-410 ◽

Cited By ~ 1

Author(s):

Zhi Li ◽

Yan Ma ◽

Xuan Liu ◽

Yi Li ◽

Fangyin Dai

Keyword(s):

Antioxidant Activity ◽

Clinical Practice ◽

Antimicrobial Peptides ◽

Structure Function ◽

Broad Spectrum ◽

Antibacterial Properties ◽

Antimicrobial Activities ◽

Vital Role ◽

Bacteria Resistance

Abstract Antimicrobial peptides (AMPs) are a type of small molecular proteins that play a vital role in the resistance to alien pathogens. AMPs are widespread in bacteria, archaea, protists, fungi, plants and animals. AMPs have a broad spectrum of antimicrobial activities and they rarely induce bacteria resistance; thus, they are thought to be good candidates for antibiotics in clinical practice. Recently, AMPs are increasingly attracting attention because of their outstanding features and functions. In addition to their known antibacterial properties, some kinds of AMPs have also been reported to have antiviral, anticancer, antiparasitic, and antioxidant activity. In this review, we introduce the diversity of AMPs, including their structure, function and related mechanisms. We focus primarily on recent studies of silkworm AMPs and summarize their classification, activities and possible mechanisms. Finally, based on the review, probable directions and perspectives for studies of the AMPs of silkworm are discussed and proposed.

Download Full-text

Mode of Action of Chronotropic Agents in Cardiac Purkinje Fibers

The Journal of General Physiology ◽

10.1085/jgp.64.3.320 ◽

1974 ◽

Vol 64 (3) ◽

pp. 320-342 ◽

Cited By ~ 40

Author(s):

Richard W. Tsien

Keyword(s):

Surface Charge ◽

External Surface ◽

Membrane Surface ◽

Internal Surface ◽

Phosphodiesterase Inhibitors ◽

Common Mechanism ◽

Pacemaker Activity ◽

Response Curves ◽

Voltage Shift ◽

Cardiac Purkinje Fibers

Hauswirth et al. (1968) proposed that epinephrine acts on iKK2 by adding its own positive charge to the external membrane surface near the iKK2 channel. This hypothesis was tested by using noncationic compounds, theophylline and R07-2956, which mimicked epinephrine's effects on pacemaker activity and on iKK2. In maximally effective doses, theophylline or R07-2956 occluded the effect of epinephrine, indicating a shared final common mechanism. Since theophylline and R07-2956 are noncationic at pH 7.4, the common mechanism cannot be a direct change in external surface charge. On the contrary, epinephrine does not interfere with the voltage shift produced by La+++, which is thought to modify the external surface charge. The results argue against the original hypothesis but leave open the possibility that an alteration in internal surface charge generates the observed voltage shift. The potency of theophylline and R07-2956 as phosphodiesterase inhibitors suggests that the final common mechanism begins with the elevation of intracellular cyclic AMP, leading to a saturable process which limits the voltage shift's magnitude. This hypothesis is used to generate dose-response curves describing the combined effects of epinephrine and theophylline, and these are compared with experimental data.

Download Full-text

Antimicrobial Peptides from Rat-Tailed Maggots of the Drone Fly Eristalis tenax Show Potent Activity against Multidrug-Resistant Gram-Negative Bacteria

Microorganisms ◽

10.3390/microorganisms8050626 ◽

2020 ◽

Vol 8 (5) ◽

pp. 626 ◽

Cited By ~ 1

Author(s):

Rolf Hirsch ◽

Jochen Wiesner ◽

Armin Bauer ◽

Alexander Marker ◽

Heiko Vogel ◽

...

Keyword(s):

Antimicrobial Peptides ◽

Multidrug Resistant ◽

Therapeutic Window ◽

Gram Negative Bacteria ◽

Strong Activity ◽

Gram Negative ◽

Physiological Conditions ◽

Manure Storage ◽

Defense Molecules ◽

Generation Sequencing

The spread of multidrug-resistant Gram-negative bacteria is an increasing threat to human health, because novel compound classes for the development of antibiotics have not been discovered for decades. Antimicrobial peptides (AMPs) may provide a much-needed breakthrough because these immunity-related defense molecules protect many eukaryotes against Gram-negative pathogens. Recent concepts in evolutionary immunology predict the presence of potent AMPs in insects that have adapted to survive in habitats with extreme microbial contamination. For example, the saprophagous and coprophagous maggots of the drone fly Eristalis tenax (Diptera) can flourish in polluted aquatic habitats, such as sewage tanks and farmyard liquid manure storage pits. We used next-generation sequencing to screen the E. tenax immunity-related transcriptome for AMPs that are synthesized in response to the injection of bacterial lipopolysaccharide. We identified 22 AMPs and selected nine for larger-scale synthesis to test their activity against a broad spectrum of pathogens, including multidrug-resistant Gram-negative bacteria. Two cecropin-like peptides (EtCec1-a and EtCec2-a) and a diptericin-like peptide (EtDip) displayed strong activity against the pathogens, even under simulated physiological conditions, and also achieved a good therapeutic window. Therefore, these AMPs could be used as leads for the development of novel antibiotics.

Download Full-text

Cell Membrane-Interrupting Antimicrobial Peptides from Isatis indigotica Fortune Isolated by a Bacillus subtilis Expression System

Biomolecules ◽

10.3390/biom10010030 ◽

2019 ◽

Vol 10 (1) ◽

pp. 30 ◽

Cited By ~ 4

Author(s):

Jia Wu ◽

Hafiz Muhammad Khalid Abbas ◽

Jiale Li ◽

Yuan Yuan ◽

Yunjun Liu ◽

...

Keyword(s):

Bacillus Subtilis ◽

Cell Membrane ◽

Antimicrobial Peptides ◽

Viral Infections ◽

Clinical Medicine ◽

Raw Materials ◽

Expression System ◽

Electrical Potential ◽

Antimicrobial Activities ◽

Isatis Indigotica

The situation of drug resistance has become more complicated due to the scarcity of plant resistance genes, and overcoming this challenge is imperative. Isatis indigotica has been used for the treatment of wounds, viral infections, and inflammation for centuries. Antimicrobial peptides (AMPs) are found in all classes of life ranging from prokaryotes to eukaryotes. To identify AMPs, I. indigotica was explored using a novel, sensitive, and high-throughput Bacillus subtilis screening system. We found that IiR515 and IiR915 exhibited significant antimicrobial activities against a variety of bacterial (Xanthomonas oryzae, Ralstonia solanacearum, Clavibacter michiganensis, and C. fangii) and fungal (Phytophthora capsici and Botrytis cinerea) pathogens. Scanning electron microscope and cytometric analysis revealed the possible mechanism of these peptides, which was to target and disrupt the bacterial cell membrane. This model was also supported by membrane fluidity and electrical potential analyses. Hemolytic activity assays revealed that these peptides may act as a potential source for clinical medicine development. In conclusion, the plant-derived novel AMPs IiR515 and IiR915 are effective biocontrol agents and can be used as raw materials in the drug discovery field.

Download Full-text

A Head-to-Head Comparison of the Antimicrobial Activities of 30 Ultra-Short Antimicrobial Peptides Against Staphylococcus aureus, Pseudomonas aeruginosa and Candida albicans

International Journal of Peptide Research and Therapeutics ◽

10.1007/s10989-014-9440-x ◽

2014 ◽

Vol 21 (1) ◽

pp. 21-28 ◽

Cited By ~ 7

Author(s):

Qiu Ying Lau ◽

Xing Yao Choo ◽

Zhi Xue Lim ◽

Xin Ni Kong ◽

Fui Mee Ng ◽

...

Keyword(s):

Staphylococcus Aureus ◽

Pseudomonas Aeruginosa ◽

Candida Albicans ◽

Antimicrobial Peptides ◽

Antimicrobial Activities

Download Full-text

cDNA cloning and functional characterisation of four antimicrobial peptides from Paa spinosa

Zeitschrift für Naturforschung C ◽

10.1515/znc-2015-4220 ◽

2015 ◽

Vol 70 (9-10) ◽

pp. 251-256 ◽

Cited By ~ 3

Author(s):

Bao Juan Dong ◽

Zhong Gen Zhan ◽

Rong Quan Zheng ◽

Wen Chen ◽

Jin Jin Min

Keyword(s):

Antimicrobial Peptides ◽

Chemical Properties ◽

Antimicrobial Activities ◽

Innate Immune ◽

Gram Negative Bacteria ◽

Bacterial Strains ◽

Small Peptides ◽

Future Design ◽

Functional Characterisation ◽

Race Technique

Abstract Antimicrobial peptides (AMPs) are small peptides found in many organisms defending themselves against pathogens. AMPs form the first line of host defence against pathogenic infections and are key components of the innate immune system of amphibians. In the current study, cDNAs of precursors of four novel antimicrobial peptides in the skin of Paa spinosa were cloned and sequenced using the 3′-RACE technique. Mature peptides, named spinosan A–D, encoded by the cDNAs were chemically synthesized and their chemical properties were predicted. The antimicrobial, antioxidative, cyotoxic and haemolytic activities of these four AMPs were determined. While the synthesised spinosans A–C exhibited no activity towards any of the bacterial strains tested, spinosan-D exhibited weak but broad-spectrum antimicrobial activities against Gram-positive and Gram-negative bacteria. All peptides were weakly haemolytic towards rabbit erythrocytes, had a strong antioxidative activity, and a low cytotoxic activity against HeLa cells. These findings provide helpful insights that may be useful in the future design of anti-infective peptide agents.

Download Full-text