Unveiling the Multifaceted Mechanisms of Antibacterial Activity of Buforin II and Frenatin 2.3S Peptides from Skin Micro-Organs of the Orinoco Lime Treefrog (Sphaenorhynchus lacteus)

Amphibian skin is a rich source of natural compounds with diverse antimicrobial and immune defense properties. Our previous studies showed that the frog skin secretions obtained by skin micro-organs from various species of Colombian anurans have antimicrobial activities against bacteria and viruses. We purified for the first time two antimicrobial peptides from the skin micro-organs of the Orinoco lime treefrog (Sphaenorhynchus lacteus) that correspond to Buforin II (BF2) and Frenatin 2.3S (F2.3S). Here, we have synthesized the two peptides and tested them against Gram-negative and Gram-positive bacteria, observing an effective bactericidal activity at micromolar concentrations. Evaluation of BF2 and F2.3S membrane destabilization activity on bacterial cell cultures and synthetic lipid bilayers reveals a distinct membrane interaction mechanism. BF2 agglutinates E. coli cells and synthetic vesicles, whereas F2.3S shows a high depolarization and membrane destabilization activities. Interestingly, we found that F2.3S is able to internalize within bacterial cells and can bind nucleic acids, as previously reported for BF2. Moreover, bacterial exposure to both peptides alters the expression profile of genes related to stress and resistance response. Overall, these results show the multifaceted mechanism of action of both antimicrobial peptides that can provide alternative tools in the fight against bacterial resistance.

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Mammals’ antimicrobial peptides: potential and limitations for the treatment of Staphylococcus aureus infections

Revista de Medicina ◽

10.11606/issn.1679-9836.v97i1p59-70 ◽

2018 ◽

Vol 97 (1) ◽

pp. 59-70

Author(s):

Gabriel Bernardes Baron ◽

Nathália Franchon Marques Tejada ◽

Fabiano Pinheiro da Silva

Keyword(s):

Staphylococcus Aureus ◽

Antimicrobial Peptides ◽

English Language ◽

Bacterial Resistance ◽

Antimicrobial Activities ◽

Secondary Effects ◽

Antitumor Effects ◽

Routes Of Administration ◽

Living Organisms ◽

Do So

Antimicrobial peptides (AMPs) are small molecules produced by virtually all living organisms as a part of the innate immune system. They present a broad spectrum antimicrobial activity against a myriad of microorganisms, but also anti-inflammatory, immunomodulatory and antitumor effects, among others. Therefore, it was our objective to compile and analyze the current information about natural and synthetic AMPs, regarding their general mechanisms of action, potentials, and limitations for clinical use, especially for the treatment of Staphylococcus aureus infections. Furthermore, we intended to briefly discuss new routes of administration and the emergence of bacterial resistance to AMPs. To do so, two databases, PubMed and Scopus, and the keywords “Staphylococcus aureus”, “antimicrobial peptide” and “novel antibiotics” were used, and the articles were filtered by the English language for the period between 2011 and 2016. We found that AMPs possess different properties, with characteristic antimicrobial activities and secondary effects. Moreover, we also pointed some modifications that could be used to design new AMPs and different routes of administration that could be used to improve AMP capacity or to adapt it to a specific purpose, such as preventing biofilm formation in catheters or treating a specific disease. On the other hand, they also present limitations that include: development of bacterial resistance, cytotoxicity, and reduced stability, sometimes lower efficacy when compared to the actual treatment, high costs of production and also some inconsistent results between articles, which we believe that may be related to differences in methods and/or strains of S. aureus investigated.

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Antimicrobial Activities and Structures of Two Linear Cationic Peptide Families with Various Amphipathic β-Sheet and α-Helical Potentials

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.49.12.4957-4964.2005 ◽

2005 ◽

Vol 49 (12) ◽

pp. 4957-4964 ◽

Cited By ~ 70

Author(s):

Yi Jin ◽

Janet Hammer ◽

Michelle Pate ◽

Yu Zhang ◽

Fang Zhu ◽

...

Keyword(s):

Antimicrobial Activity ◽

Antimicrobial Peptides ◽

Plasma Membranes ◽

Membrane Lipids ◽

Lipid Vesicles ◽

Selective Advantage ◽

Antimicrobial Activities ◽

Helical Conformation ◽

Bacterial Cells ◽

Β Sheet

ABSTRACT Many naturally occurring antimicrobial peptides comprise cationic linear sequences with the potential to adopt an amphipathic α-helical conformation. We designed a linear 18-residue peptide that adopted an amphipathic β-sheet structure when it was bound to lipids. In comparison to a 21-residue amphipathic α-helical peptide of equal charge and hydrophobicity, this peptide possessed more similar antimicrobial activity and greater selectivity in binding to and inducing leakage in vesicles composed of bacterial membrane lipids than vesicles composed of mammalian membrane lipids (J. Blazyk, R. Weigand, J. Klein, J. Hammer, R. M. Epand, R. F. Epand, W. L. Maloy, and U. P. Kari, J. Biol. Chem. 276:27899-27906, 2001). Here, we compare two systematically designed families of linear cationic peptides to evaluate the importance of amphipathicity for determination of antimicrobial activity. Each peptide contains six lysine residues and is amidated at the carboxyl terminus. The first family consists of five peptides with various capacities to form amphipathic β-sheet structures. The second family consists of six peptides with various potentials to form amphipathic α helices. Only those peptides that can form a highly amphipathic structure (either a β sheet or an α helix) possessed significant antimicrobial activities. Striking differences in the abilities to bind to and induce leakage in membranes and lipid vesicles were observed for the two families. Overall, the amphipathic β-sheet peptides are less lytic than their amphipathic α-helical counterparts, particularly toward membranes containing phosphatidylcholine, a lipid commonly found in mammalian plasma membranes. Thus, it appears that antimicrobial peptides that can form an amphipathic β-sheet conformation may offer a selective advantage in targeting bacterial cells.

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The PhoQ-Activating Potential of Antimicrobial Peptides Contributes to Antimicrobial Efficacy and Is Predictive of the Induction of Bacterial Resistance

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00854-07 ◽

2007 ◽

Vol 51 (12) ◽

pp. 4374-4381 ◽

Cited By ~ 9

Author(s):

Jason Kindrachuk ◽

Nicole Paur ◽

Carla Reiman ◽

Erin Scruten ◽

Scott Napper

Keyword(s):

Antimicrobial Peptides ◽

Bacterial Resistance ◽

Immune Defense ◽

Minimal Bactericidal Concentration ◽

Adaptive Responses ◽

Bacterial Strains ◽

Concentration Data ◽

Antimicrobial Efficiency ◽

Novel Strategy ◽

Therapeutic Administration

ABSTRACT Antimicrobial peptides (AMPs) are among the leading candidates to replace antibiotics which have been rendered ineffective by the evolution of resistant bacterial strains. Concerns do exist, however, that the therapeutic administration of AMPs may also select for resistant strains but with much more dire consequences, as these peptides represent an endogenous and essential component of host immune defense. The recent demonstration that AMPs function as ligands for the bacterial sensory kinase PhoQ for the initiation of virulence and adaptive responses lends credence to these concerns. While the ability to serve as PhoQ ligands suggests that the therapeutic administration of AMPs could (i) exacerbate infections by promoting bacterial virulence and (ii) select resistant mutants by encouraging adaptive behaviors, it also provides a rational basis for AMP selection and optimization. Here, we demonstrate that derivatives of a representative AMP have differential abilities to serve as PhoQ ligands and that this correlates with the ability to induce bacterial adaptive responses. We propose that PhoQ-activating potential is a logical parameter for AMP optimization and introduce a novel strategy for the treatment of minimal bactericidal concentration data that permits the discrimination and quantification of the contributions of PhoQ-activating potential and direct antimicrobial activity to net antimicrobial efficiency.

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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.

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Hydramacin-1 in Action: Scrutinizing the Barnacle Model

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.02498-12 ◽

2013 ◽

Vol 57 (7) ◽

pp. 2955-2966 ◽

Cited By ~ 7

Author(s):

Matthias Michalek ◽

Bruno Vincent ◽

Rainer Podschun ◽

Joachim Grötzinger ◽

Burkhard Bechinger ◽

...

Keyword(s):

Antimicrobial Peptides ◽

Lipid Bilayers ◽

Binding Constants ◽

Head Group ◽

Target Cells ◽

Bacterial Cells ◽

Bacterial Strains ◽

Wide Range ◽

A Minor ◽

Lipid Interaction

ABSTRACTHydramacin-1 (HM1) from the metazoanHydraexerts antimicrobial activity against a wide range of bacterial strains. Notably, HM1 induces the aggregation of bacterial cells, accompanied by precipitation. To date, the proposed mechanism of peptide-lipid interaction, termed the barnacle model, has not been described on the molecular level. Here, we show by biochemical and biophysical techniques that the lipid-peptide interactions of HM1 are initiated by electrostatic and hydrophobic effects, in particular, by tryptophan and neighboring polar amino acid residues that cause an interfacial localization of the peptide between two self-contained lipid bilayers. The high binding constants of HM1 upon lipid interaction are in the range of other potent antimicrobial peptides, e.g., magainin, and can be reasonably explained by two distinct epitopes on the surface of the peptide's global structure, which both contain SWT(K/R) motifs. The residues of this motif favor localization of the peptide in the head group region of phospholipid bilayers up to a penetration depth of 4 Å and a minor participation of the lipids' hydrocarbon regions. Our results expand the knowledge about the molecular modes of action antimicrobial peptides use to tackle their target cells. Furthermore, the aggregation of living bacteria by HM1 was observed for a broad range of Gram-positive and Gram-negative bacteria. Therefore, the detailed view of peptide-lipid interactions described by the barnacle model consolidates it among the established models.

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Antimicrobial Peptides from Black Soldier Fly (Hermetia illucens) as Potential Antimicrobial Factors Representing an Alternative to Antibiotics in Livestock Farming

Animals ◽

10.3390/ani11071937 ◽

2021 ◽

Vol 11 (7) ◽

pp. 1937

Author(s):

Jing Xia ◽

Chaorong Ge ◽

Huaiying Yao

Keyword(s):

Antimicrobial Peptides ◽

Bacterial Resistance ◽

General Information ◽

Immune Defense ◽

Livestock Farming ◽

Black Soldier Fly ◽

Hermetia Illucens ◽

Pathogen Invasion ◽

Functional Investigation ◽

New Generation

Functional antimicrobial peptides (AMPs) are an important class of effector molecules of innate host immune defense against pathogen invasion. Inability of microorganisms to develop resistance against the majority of AMPs has made them alternatives to antibiotics, contributing to the development of a new generation of antimicrobials. Due to extensive biodiversity, insects are one of the most abundant sources of novel AMPs. Notably, black soldier fly insect (BSF; Hermetia illucens (Diptera: Stratiomyidae)) feeds on decaying substrates and displays a supernormal capacity to survive under adverse conditions in the presence of abundant microorganisms, therefore, BSF is one of the most promising sources for identification of AMPs. However, discovery, functional investigation, and drug development to replace antibiotics with AMPs from Hermetia illucens remain in a preliminary stage. In this review, we provide general information on currently verified AMPs of Hermetia illucens, describe their potential medical value, discuss the mechanism of their synthesis and interactions, and consider the development of bacterial resistance to AMPs in comparison with antibiotics, aiming to provide a candidate for substitution of antibiotics in livestock farming or, to some extent, for blocking the horizontal transfer of resistance genes in the environment, which is beneficial to human and animal welfare.

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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.

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The Lactococcal dgkB (yecE) and dxsA Genes for Lipid Metabolism Are Involved in the Resistance to Cell Envelope-Acting Antimicrobials

International Journal of Molecular Sciences ◽

10.3390/ijms22031014 ◽

2021 ◽

Vol 22 (3) ◽

pp. 1014

Author(s):

Aleksandra Tymoszewska ◽

Tamara Aleksandrzak-Piekarczyk

Keyword(s):

Antimicrobial Peptides ◽

Bacterial Resistance ◽

Antimicrobial Agents ◽

Cytoplasmic Membrane ◽

Cross Resistance ◽

Resistant Bacteria ◽

Membrane Targeting ◽

Nucleotide Polymorphisms ◽

Next Generation ◽

Lipid Ii

The emergence of antibiotic-resistant bacteria led to an urgent need for next-generation antimicrobial agents with novel mechanisms of action. The use of positively charged antimicrobial peptides that target cytoplasmic membrane is an especially promising strategy since essential functions and the conserved structure of the membrane hinder the development of bacterial resistance. Aureocin A53- and enterocin L50-like bacteriocins are highly cationic, membrane-targeting antimicrobial peptides that have potential as next-generation antibiotics. However, the mechanisms of resistance to these bacteriocins and cross-resistance against antibiotics must be examined before application to ensure their safe use. Here, in the model bacterium Lactococcus lactis, we studied the development of resistance to selected aureocin A53- and enterocin L50-like bacteriocins and its correlation with antibiotics. First, to generate spontaneous resistant mutants, L.lactis was exposed to bacteriocin BHT-B. Sequencing of their genomes revealed single nucleotide polymorphisms (SNPs) in the dgkB (yecE) and dxsA genes encoding diacylglycerol kinase and 1-deoxy-D-xylulose 5-phosphate synthase, respectively. Then, selected mutants underwent susceptibility tests with a wide array of bacteriocins and antibiotics. The highest alterations in the sensitivity of studied mutants were seen in the presence of cytoplasmic membrane targeting bacteriocins (K411, Ent7, EntL50, WelM, SalC, nisin) and antibiotics (daptomycin and gramicidin) as well as lipid II cycle-blocking bacteriocins (nisin and Lcn972) and antibiotics (bacitracin). Interestingly, decreased via the SNPs accumulation sensitivity to membrane-active bacteriocins and antibiotics resulted in the concurrently increased vulnerability to bacitracin, carbenicillin, or chlortetracycline. It is suspected that SNPs may result in alterations to the efficiency of the nascent enzymes rather than a total loss of their function as neither deletion nor overexpression of dxsA restored the phenotype observed in spontaneous mutants.

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A Real-Time Thermal Sensor System for Quantifying the Inhibitory Effect of Antimicrobial Peptides on Bacterial Adhesion and Biofilm Formation

Sensors ◽

10.3390/s21082771 ◽

2021 ◽

Vol 21 (8) ◽

pp. 2771

Author(s):

Tobias Wieland ◽

Julia Assmann ◽

Astrid Bethe ◽

Christian Fidelak ◽

Helena Gmoser ◽

...

Keyword(s):

Antimicrobial Peptides ◽

Real Time ◽

Bacterial Adhesion ◽

Biofilm Formation ◽

Pathogenic Bacteria ◽

Bovine Mastitis ◽

Inhibitory Effect ◽

Thermal Sensor ◽

Bacterial Cells ◽

Static Conditions

The increasing rate of antimicrobial resistance (AMR) in pathogenic bacteria is a global threat to human and veterinary medicine. Beyond antibiotics, antimicrobial peptides (AMPs) might be an alternative to inhibit the growth of bacteria, including AMR pathogens, on different surfaces. Biofilm formation, which starts out as bacterial adhesion, poses additional challenges for antibiotics targeting bacterial cells. The objective of this study was to establish a real-time method for the monitoring of the inhibition of (a) bacterial adhesion to a defined substrate and (b) biofilm formation by AMPs using an innovative thermal sensor. We provide evidence that the thermal sensor enables continuous monitoring of the effect of two potent AMPs, protamine and OH-CATH-30, on surface colonization of bovine mastitis-associated Escherichia (E.) coli and Staphylococcus (S.) aureus. The bacteria were grown under static conditions on the surface of the sensor membrane, on which temperature oscillations generated by a heater structure were detected by an amorphous germanium thermistor. Bacterial adhesion, which was confirmed by white light interferometry, caused a detectable amplitude change and phase shift. To our knowledge, the thermal measurement system has never been used to assess the effect of AMPs on bacterial adhesion in real time before. The system could be used to screen and evaluate bacterial adhesion inhibition of both known and novel AMPs.

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Pseudomonas aeruginosa Oligoribonuclease Controls Susceptibility to Polymyxin B by Regulating Pel Exopolysaccharide Production

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.02072-21 ◽

2022 ◽

Author(s):

Baopeng Yang ◽

Yujun Jiang ◽

Yongxin Jin ◽

Fang Bai ◽

Zhihui Cheng ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Bacterial Resistance ◽

Defense Mechanism ◽

Extracellular Polysaccharide ◽

Opportunistic Pathogen ◽

Polymyxin B ◽

Guanosine Monophosphate ◽

Extracellular Dna ◽

Bacterial Cells ◽

Bacterial Survival

Polymyxins are considered as the last resort antibiotics to treat infections caused by multidrug-resistant Gram negative pathogens. Pseudomonas aeruginosa is an opportunistic pathogen that causes various infections in humans. Proteins involved in lipopolysaccharide modification and maintaining inner and outer membrane integrities have been found to contribute to the bacterial resistance to polymyxins. Oligoribonuclease (Orn) is an exonuclease that regulates the homeostasis of intracellular (3'-5')-cyclic dimeric guanosine monophosphate (c-di-GMP), thereby regulating the production of extracellular polysaccharide in P. aeruginosa . Previously, we demonstrated that Orn affects the bacterial resistance to fluoroquinolone, β-lactam and aminoglycoside antibiotics. In this study, we found that mutation of orn increased the bacterial survival following polymyxin B treatment in a wild type P. aeruginosa strain PA14. Overexpression of c-di-GMP degradation enzymes in the orn mutant reduced the bacterial survival. By using a fluorescence labeled polymyxin B, we found that mutation of orn increased the bacterial surface bound polymyxin B. Deletion of the Pel synthesis genes or treatment with a Pel hydrolase reduced the surface bound polymyxin B and bacterial survival. We further demonstrated that Pel binds to extracellular DNA (eDNA), which traps polymyxin B and thus protects the bacterial cells. Collectively, our results revealed a novel defense mechanism against polymyxin in P. aeruginosa .

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