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

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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Combating bacterial resistance by combination of antibiotics with antimicrobial peptides

Pure and Applied Chemistry ◽

10.1515/pac-2018-0707 ◽

2019 ◽

Vol 91 (2) ◽

pp. 199-209 ◽

Cited By ~ 8

Author(s):

Dean E. Sheard ◽

Neil M. O’Brien-Simpson ◽

John D. Wade ◽

Frances Separovic

Keyword(s):

Antimicrobial Peptides ◽

Bacterial Infections ◽

Bacterial Resistance ◽

Synergistic Effects ◽

Resistance Mechanisms ◽

Bacterial Strains ◽

Diverse Range ◽

Recent Emergence ◽

Agricultural Industries ◽

Conventional Antibiotics

Abstract The overuse of antibiotics in the healthcare and agricultural industries has led to the worldwide spread of bacterial resistance. The recent emergence of multidrug resistant (MDR) bacteria has resulted in a call for the development of novel strategies to address this global issue. Research on a diverse range of antimicrobial peptides (AMPs) has shown promising activity against several resistant strains. Increased understanding of the mode of action of AMPs has shown similarity and complementarity to conventional antibiotics and the combination of both has led to synergistic effects in some cases. Combination therapy has been widely used to combat MDR bacterial infections and the recent focus on their application with AMPs may allow antibiotics to be effective against resistant bacterial strains. By conjugation of an antibiotic onto an AMP, a compound may be produced with possibly greater activity and with reduced side-effects and toxicity. The AMP in these conjugates may also act as a unique adjuvant for the antibiotic by disrupting the resistance mechanisms used by bacteria thus allowing the antibiotic to once again be effective. This mini-review outlines some of the current and past work in combining AMPs with conventional antibiotics as strategies to address bacterial resistance.

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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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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)

International Journal of Molecular Sciences ◽

10.3390/ijms19082170 ◽

2018 ◽

Vol 19 (8) ◽

pp. 2170 ◽

Cited By ~ 3

Author(s):

Carolina Muñoz-Camargo ◽

Vivian Salazar ◽

Laura Barrero-Guevara ◽

Sandra Camargo ◽

Angela Mosquera ◽

...

Keyword(s):

Antimicrobial Peptides ◽

Lipid Bilayers ◽

Bacterial Resistance ◽

Interaction Mechanism ◽

Antimicrobial Activities ◽

Immune Defense ◽

Bacterial Cells ◽

Amphibian Skin ◽

Resistance Response ◽

Membrane Destabilization

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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Challenge in the Discovery of New Drugs: Antimicrobial Peptides against WHO-List of Critical and High-Priority Bacteria

Pharmaceutics ◽

10.3390/pharmaceutics13060773 ◽

2021 ◽

Vol 13 (6) ◽

pp. 773

Author(s):

Cesar Augusto Roque-Borda ◽

Patricia Bento da Silva ◽

Mosar Corrêa Rodrigues ◽

Ricardo Bentes Azevedo ◽

Leonardo Di Filippo ◽

...

Keyword(s):

Antimicrobial Peptides ◽

Conventional Treatment ◽

Bacterial Resistance ◽

Resistance Mechanisms ◽

New Drugs ◽

Resistant Bacteria ◽

Multiple Resistance ◽

Clinical Use ◽

Bacterial Strains ◽

Bacterial Cell Membrane

Bacterial resistance has intensified in recent years due to the uncontrolled use of conventional drugs, and new bacterial strains with multiple resistance have been reported. This problem may be solved by using antimicrobial peptides (AMPs), which fulfill their bactericidal activity without developing much bacterial resistance. The rapid interaction between AMPs and the bacterial cell membrane means that the bacteria cannot easily develop resistance mechanisms. In addition, various drugs for clinical use have lost their effect as a conventional treatment; however, the synergistic effect of AMPs with these drugs would help to reactivate and enhance antimicrobial activity. Their efficiency against multi-resistant and extensively resistant bacteria has positioned them as promising molecules to replace or improve conventional drugs. In this review, we examined the importance of antimicrobial peptides and their successful activity against critical and high-priority bacteria published in the WHO list.

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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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In Vitro Evaluation of Five Antimicrobial Peptides against the Plant Pathogen Erwinia amylovora

Biomolecules ◽

10.3390/biom11040554 ◽

2021 ◽

Vol 11 (4) ◽

pp. 554

Author(s):

Rafael J. Mendes ◽

Laura Regalado ◽

João P. Luz ◽

Natália Tassi ◽

Cátia Teixeira ◽

...

Keyword(s):

Flow Cytometry ◽

Antimicrobial Peptides ◽

Erwinia Amylovora ◽

Growth Curves ◽

Fruit Trees ◽

Membrane Permeabilization ◽

Control Measures ◽

Minimal Bactericidal Concentration ◽

Pome Fruit

Fire blight is a major pome fruit trees disease that is caused by the quarantine phytopathogenic Erwinia amylovora, leading to major losses, namely, in pear and apple productions. Nevertheless, no effective sustainable control treatments and measures have yet been disclosed. In that regard, antimicrobial peptides (AMPs) have been proposed as an alternative biomolecule against pathogens but some of those AMPs have yet to be tested against E. amylovora. In this study, the potential of five AMPs (RW-BP100, CA-M, 3.1, D4E1, and Dhvar-5) together with BP100, were assessed to control E. amylovora. Antibiograms, minimal inhibitory, and bactericidal concentrations (minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC), growth and IC50 were determined and membrane permeabilization capacity was evaluated by flow cytometry analysis and colony-forming units (CFUs) plate counting. For the tested AMPs, the higher inhibitory and bactericidal capacity was observed for RW-BP100 and CA-M (5 and 5–8 µM, respectively for both MIC and MBC), whilst for IC50 RW-BP100 presented higher efficiency (2.8 to 3.5 µM). Growth curves for the first concentrations bellow MIC showed that these AMPs delayed E. amylovora growth. Flow cytometry disclosed faster membrane permeabilization for CA-M. These results highlight the potential of RW-BP100 and CA-M AMPs as sustainable control measures against E. amylovora.

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Alkaloid-Rich Crude Extracts, Fractions and Piperamide Alkaloids of Piper guineense Possess Promising Antibacterial Effects

Antibiotics ◽

10.3390/antibiotics7040098 ◽

2018 ◽

Vol 7 (4) ◽

pp. 98 ◽

Cited By ~ 5

Author(s):

Eunice Mgbeahuruike ◽

Pia Fyhrquist ◽

Heikki Vuorela ◽

Riitta Julkunen-Tiitto ◽

Yvonne Holm

Keyword(s):

Antibacterial Activity ◽

Pathogenic Bacteria ◽

Bacterial Resistance ◽

Hot Water ◽

Bacterial Strains ◽

Inhibitory Effects ◽

Piper Guineense ◽

E Coli ◽

Growth Inhibitory ◽

Derivatives Of

Piper guineense is a food and medicinal plant commonly used to treat infectious diseases in West-African traditional medicine. In a bid to identify new antibacterial compounds due to bacterial resistance to antibiotics, twelve extracts of P. guineense fruits and leaves, obtained by sequential extraction, as well as the piperine and piperlongumine commercial compounds were evaluated for antibacterial activity against human pathogenic bacteria. HPLC-DAD and UHPLC/Q-TOF MS analysis were conducted to characterize and identify the compounds present in the extracts with promising antibacterial activity. The extracts, with the exception of the hot water decoctions and macerations, contained piperamide alkaloids as their main constituents. Piperine, dihydropiperine, piperylin, dihydropiperylin or piperlonguminine, dihydropiperlonguminine, wisanine, dihydrowisanine and derivatives of piperine and piperidine were identified in a hexane extract of the leaf. In addition, some new piperamide alkaloids were identified, such as a piperine and a piperidine alkaloid derivative and two unknown piperamide alkaloids. To the best of our knowledge, there are no piperamides reported in the literature with similar UVλ absorption maxima and masses. A piperamide alkaloid-rich hexane leaf extract recorded the lowest MIC of 19 µg/mL against Sarcina sp. and gave promising growth inhibitory effects against S. aureus and E. aerogenes as well, inhibiting the growth of both bacteria with a MIC of 78 µg/mL. Moreover, this is the first report of the antibacterial activity of P. guineense extracts against Sarcina sp. and E. aerogenes. Marked growth inhibition was also obtained for chloroform extracts of the leaves and fruits against P. aeruginosa with a MIC value of 78 µg/mL. Piperine and piperlongumine were active against E. aerogenes, S. aureus, E. coli, S. enterica, P. mirabilis and B. cereus with MIC values ranging from 39–1250 µg/mL. Notably, the water extracts, which were almost devoid of piperamide alkaloids, were not active against the bacterial strains. Our results demonstrate that P. guineense contains antibacterial alkaloids that could be relevant for the discovery of new natural antibiotics.

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Antimicrobial Peptides: Mechanisms of Action and Resistance

Journal of Dental Research ◽

10.1177/0022034516679973 ◽

2016 ◽

Vol 96 (3) ◽

pp. 254-260 ◽

Cited By ~ 177

Author(s):

B. Bechinger ◽

S.-U. Gorr

Keyword(s):

Cell Wall ◽

Cell Membrane ◽

Antimicrobial Peptides ◽

Bacterial Resistance ◽

Rare Event ◽

Mechanisms Of Action ◽

Current Evidence ◽

Aggregation State ◽

Host Defense Peptides ◽

Bacterial Membranes

More than 40 antimicrobial peptides and proteins (AMPs) are expressed in the oral cavity. These AMPs have been organized into 6 functional groups, 1 of which, cationic AMPs, has received extensive attention in recent years for their promise as potential antibiotics. The goal of this review is to describe recent advances in our understanding of the diverse mechanisms of action of cationic AMPs and the bacterial resistance against these peptides. The recently developed peptide GL13K is used as an example to illustrate many of the discussed concepts. Cationic AMPs typically exhibit an amphipathic conformation, which allows increased interaction with negatively charged bacterial membranes. Peptides undergo changes in conformation and aggregation state in the presence of membranes; conversely, lipid conformation and packing can adapt to the presence of peptides. As a consequence, a single peptide can act through several mechanisms depending on the peptide’s structure, the peptide:lipid ratio, and the properties of the lipid membrane. Accumulating evidence shows that in addition to acting at the cell membrane, AMPs may act on the cell wall, inhibit protein folding or enzyme activity, or act intracellularly. Therefore, once a peptide has reached the cell wall, cell membrane, or its internal target, the difference in mechanism of action on gram-negative and gram-positive bacteria may be less pronounced than formerly assumed. While AMPs should not cause widespread resistance due to their preferential attack on the cell membrane, in cases where specific protein targets are involved, the possibility exists for genetic mutations and bacterial resistance. Indeed, the potential clinical use of AMPs has raised the concern that resistance to therapeutic AMPs could be associated with resistance to endogenous host-defense peptides. Current evidence suggests that this is a rare event that can be overcome by subtle structural modifications of an AMP.

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The Multidrug Resistance-Reversing Activity of a Novel Antimicrobial Peptide

Cancers ◽

10.3390/cancers12071963 ◽

2020 ◽

Vol 12 (7) ◽

pp. 1963

Author(s):

Qiu-Xu Teng ◽

Xiaofang Luo ◽

Zi-Ning Lei ◽

Jing-Quan Wang ◽

John Wurpel ◽

...

Keyword(s):

Multidrug Resistance ◽

Antimicrobial Peptides ◽

Anticancer Drugs ◽

Anticancer Agents ◽

Abc Transporters ◽

Intracellular Accumulation ◽

The Past ◽

Novel Strategy ◽

New Generation ◽

Abcb1 Transporter

The overexpression of ATP-binding cassette (ABC) transporters is a common cause of multidrug resistance (MDR) in cancers. The intracellular drug concentration of cancer cells can be decreased relative to their normal cell counterparts due to increased expression of ABC transporters acting as efflux pumps of anticancer drugs. Over the past decades, antimicrobial peptides have been investigated as a new generation of anticancer drugs and some of them were reported to have interactions with ABC transporters. In this article, we investigated several novel antimicrobial peptides to see if they could sensitize ABCB1-overexpressing cells to the anticancer drugs paclitaxel and doxorubicin, which are transported by ABCB1. It was found that peptide XH-14C increased the intracellular accumulation of ABCB1 substrate paclitaxel, which demonstrated that XH-14C could reverse ABCB1-mediated MDR. Furthermore, XH-14C could stimulate the ATPase activity of ABCB1 and the molecular dynamic simulation revealed a stable binding pose of XH-14C-ABCB1 complex. There was no change on the expression level or the location of ABCB1 transporter with the treatment of XH-14C. Our results suggest that XH-14C in combination with conventional anticancer agents could be used as a novel strategy for cancer treatment.

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Antimicrobial and Antibiofilm Peptides

Biomolecules ◽

10.3390/biom10040652 ◽

2020 ◽

Vol 10 (4) ◽

pp. 652 ◽

Cited By ~ 12

Author(s):

Angela Di Somma ◽

Antonio Moretta ◽

Carolina Canè ◽

Arianna Cirillo ◽

Angela Duilio

Keyword(s):

Antimicrobial Peptides ◽

Biofilm Formation ◽

Bacterial Resistance ◽

Antimicrobial Agents ◽

Multidrug Resistant ◽

Resistant Bacteria ◽

Antibiofilm Activity ◽

Chronic Infections ◽

Planktonic Bacteria ◽

Hostile Environments

The increasing onset of multidrug-resistant bacteria has propelled microbiology research towards antimicrobial peptides as new possible antibiotics from natural sources. Antimicrobial peptides are short peptides endowed with a broad range of activity against both Gram-positive and Gram-negative bacteria and are less prone to trigger resistance. Besides their activity against planktonic bacteria, many antimicrobial peptides also show antibiofilm activity. Biofilms are ubiquitous in nature, having the ability to adhere to virtually any surface, either biotic or abiotic, including medical devices, causing chronic infections that are difficult to eradicate. The biofilm matrix protects bacteria from hostile environments, thus contributing to the bacterial resistance to antimicrobial agents. Biofilms are very difficult to treat, with options restricted to the use of large doses of antibiotics or the removal of the infected device. Antimicrobial peptides could represent good candidates to develop new antibiofilm drugs as they can act at different stages of biofilm formation, on disparate molecular targets and with various mechanisms of action. These include inhibition of biofilm formation and adhesion, downregulation of quorum sensing factors, and disruption of the pre-formed biofilm. This review focuses on the proprieties of antimicrobial and antibiofilm peptides, with a particular emphasis on their mechanism of action, reporting several examples of peptides that over time have been shown to have activity against biofilm.

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