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Mechanisms of Antimicrobial Peptides on Pathogens

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A special issue of Antibiotics (ISSN 2079-6382). This special issue belongs to the section "Antimicrobial Peptides".

Deadline for manuscript submissions: closed (30 April 2022) | Viewed by 16374

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Special Issue Editor

Dr. Malgorzata Paduszynska

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Guest Editor

Department of Inorganic Chemistry, Faculty of Pharmacy, Medical University of Gdansk, Gdansk, Poland
Interests: antimicrobial peptides; peptide synthesis; peptide drug formulation;combination antibiotic therapy; bacterial biofilm; microbial resistance
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Antimicrobial peptides (AMPs) are considered as promising alternative for conventional antimicrobials. They are widely distributed in nature as developmental components of the innate immunity of living organisms. The majority of AMPs are cationic, amphipathic molecules that exhibit strong activity against a broad spectrum of pathogens including multi-drug resistant strains. Their ability to eliminate and prevent biofilm structures has been proven in in vitro and in vivo studies.

The most common mode of action of AMPs is disruption of cell membranes leading to microbial lysis. Due to their unique mechanism of action based on interactions with the microbial cell membrane, AMPs can act on slow-growing or even non-growing bacteria and are active against biofilm. This mode has also less risk of acquired resistance or cross-resistance with other agents than other modes of action, which makes it an attractive template for the design of new antimicrobials for specific applications.

Several mechanisms of membrane perturbation are discussed on a molecular level (e.g. toroidal pore formation, the carpet model, void formation, clustering of lipids, and membrane curvature). However, also numerous AMPs with non-conventional modes of action have been described so far. Determination and understanding the modes of action of AMPs are crucial for the rational design of improved antimicrobial compounds.

The aim of this special issue is to extend the scientific knowledge on AMPs in order to examine their modes of action, understand possible mechanims of microbial resistance, explore potential clinical applications and to survey recent achievements in this field of research.

Dr. Malgorzata Paduszynska
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Antibiotics is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2900 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

Antimicrobial peptides
mechanisms of antimicrobial activities
interactions with bacterial membrane
microbial resistance
inhibition of biofilm formation
biofilm eradication

Published Papers (6 papers)

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Research

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8 pages, 963 KiB

Open AccessCommunication

Can Immobilized Artificial Membrane Chromatography Support the Characterization of Antimicrobial Peptide Origin Derivatives?

by Krzesimir Ciura, Natalia Ptaszyńska, Hanna Kapica, Monika Pastewska, Anna Łęgowska, Krzysztof Rolka, Wojciech Kamysz, Wiesław Sawicki and Katarzyna E. Greber

Antibiotics 2021, 10(10), 1237; https://doi.org/10.3390/antibiotics10101237 - 12 Oct 2021

Cited by 6 | Viewed by 1586

Abstract

The emergence and spread of multiple drug-resistant bacteria strains caused the development of new antibiotics to be one of the most important challenges of medicinal chemistry. Despite many efforts, the commercial availability of peptide-based antimicrobials is still limited. The presented study aims to explain that immobilized artificial membrane chromatography can support the characterization of antimicrobial peptides. Consequently, the chromatographic experiments of three groups of related peptide substances: (i) short cationic lipopeptides, (ii) citropin analogs, and (iii) conjugates of ciprofloxacin and levofloxacin, with a cell-penetrating peptide were discussed. In light of the discussion of the mechanisms of action of these compounds, the obtained results were interpreted. Full article

(This article belongs to the Special Issue Mechanisms of Antimicrobial Peptides on Pathogens)

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14 pages, 1598 KiB

Open AccessArticle

Antibacterial Peptides Produced by Alcalase from Cowpea Seed Proteins

by Ali Osman, Gamal Enan, Abdul-Raouf Al-Mohammadi, Seham Abdel-Shafi, Samar Abdel-Hameid, Mahmoud Z. Sitohy and Nashwa El-Gazzar

Antibiotics 2021, 10(7), 870; https://doi.org/10.3390/antibiotics10070870 - 17 Jul 2021

Cited by 22 | Viewed by 2760

Abstract

Cowpea seed protein hydrolysates (CPH) were output from cowpea seeds applying alcalase^® from Bacillus licheniformis. CPH with an elevated level of hydrolysis was fractionated by size exclusion chromatography (SEC). Both CPH and SEC-portions showed to contain antimicrobial peptides (AMPs) as they inhibited both Gram-positive bacteria, such as Listeria monocytogenes LMG10470 (L. monocytogenes), Listeria innocua. LMG11387 (L. innocua), Staphylococcus aureus ATCC25923 (S.aureus), and Streptococcus pyogenes ATCC19615 (St.pyogenes), and Gram-negative bacteria, such as Klebsiella pnemoniae ATCC43816 (K. pnemoniae), Pseudomonas aeroginosa ATCC26853 (P. aeroginosa), Escherichia coli ATCC25468) (E.coli) and Salmonella typhimurium ATCC14028 (S. typhimurium).The data exhibited that both CPH and size exclusion chromatography-fraction 1 (SEC-F1) showed high antibacterial efficiency versus almost all the assessed bacteria. The MIC of the AMPs within SEC-F1 and CPHs were (25 µg/mL) against P. aeruginosa, E.coli and St. pyogenes. However, higher MICsof approximately 100–150 µg/mL showed for both CPHs and SEC-F1 against both S. aureus and L. innocua; it was 50 µg/mL of CPH against S.aureus. The Electro-spray-ionization-mass-spectrometry (ESI-MS) of fraction (1) revealed 10 dipeptides with a molecular masses arranged from 184 Da to 364 Da and one Penta peptide with a molecular mass of approximately 659 Da inthe case of positive ions. While the negative ions showed 4 dipeptides with the molecular masses that arranged from 330 Da to 373 Da. Transmission electron microscope (TEM) demonstrated that the SEC-F1 induced changes in the bacterial cells affected. Thus, the results suggested that the hydrolysis of cowpea seed proteins by Alcalase is an uncomplicated appliance to intensify its antibacterial efficiency. Full article

(This article belongs to the Special Issue Mechanisms of Antimicrobial Peptides on Pathogens)

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8 pages, 1654 KiB

Open AccessArticle

Catalase Protects Biofilm of Staphylococcus aureus against Daptomycin Activity

by Cristina El Haj, Mads Lichtenberg, Karen Leth Nielsen, Thomas Bjarnsholt and Peter Østrup Jensen

Antibiotics 2021, 10(5), 511; https://doi.org/10.3390/antibiotics10050511 - 30 Apr 2021

Cited by 8 | Viewed by 2529

Abstract

Daptomycin is recommended for the treatment of Staphylococcus aureus infections due to its bactericidal activity. However, its mechanism of action is poorly understood. The involvement of reactive oxygen species (ROS) in the bactericidal activity of daptomycin has been proved against planktonic S. aureus, but not against the biofilm of S. aureus. Therefore, we evaluated if ROS contributes to the effect of daptomycin against biofilm of S. aureus. Biofilms of wild type, catalase deficient and daptomycin-resistant S. aureus strains were grown in microtiter-plates. After three days, the biofilms were exposed to daptomycin with or without thiourea in the presence of a ROS indicator. After overnight incubation, the amount of ROS and the percentage of surviving bacteria were determined. The bacterial survival was higher and the amount of ROS was lower in the wild type than in the catalase deficient biofilm, demonstrating a protective effect of catalase against daptomycin. The induction of cytotoxic ROS formation by daptomycin was verified by the addition of thiourea, which reduced the amount of ROS and protected the wild type biofilm against high concentrations of daptomycin. Accordingly, only the highest concentration of daptomycin reduced the bacterial survival and increased the ROS formation in the resistant biofilm. In conclusion, daptomycin induced the production of cytotoxic levels of endogenous ROS in S. aureus biofilm and the presence of catalase protected the biofilm against the lethality of the induced ROS. Full article

(This article belongs to the Special Issue Mechanisms of Antimicrobial Peptides on Pathogens)

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19 pages, 1803 KiB

Open AccessArticle

Novel Cecropin-4 Derived Peptides against Methicillin-Resistant Staphylococcus aureus

by Jian Peng, Biswajit Mishra, Rajamohammed Khader, LewisOscar Felix and Eleftherios Mylonakis

Antibiotics 2021, 10(1), 36; https://doi.org/10.3390/antibiotics10010036 - 01 Jan 2021

Cited by 13 | Viewed by 2773

Abstract

Increasing microbial resistance, coupled with a lack of new antimicrobial discovery, has led researchers to refocus on antimicrobial peptides (AMPs) as novel therapeutic candidates. Significantly, the less toxic cecropins have gained widespread attention for potential antibacterial agent development. However, the narrow activity spectrum and long sequence remain the primary limitations of this approach. In this study, we truncated and modified cecropin 4 (41 amino acids) by varying the charge and hydrophobicity balance to obtain smaller AMPs. The derivative peptide C18 (16 amino acids) demonstrated high antibacterial activity against Gram-negative and Gram-positive bacteria, as well as yeasts. Moreover, C18 demonstrated a minimal inhibitory concentration (MIC) of 4 µg/mL against the methicillin-resistant Staphylococcus aureus (MRSA) and showed synergy with daptomycin with a fractional inhibition concentration index (FICI) value of 0.313. Similar to traditional cecropins, C18 altered the membrane potential, increased fluidity, and caused membrane breakage at 32 µg/mL. Importantly, C18 eliminated 99% persisters at 10 × MIC within 20 min and reduced the biofilm adherence by ~40% and 35% at 32 and 16 µg/mL. Besides, C18 possessed a strong binding ability with DNA at 7.8 μM and down-regulated the expression of virulence factor genes like agrA, fnb-A, and clf-1 by more than 5-fold (p < 0.05). Interestingly, in the Galleria mellonella model, C18 rescued more than 80% of larva infected with the MRSA throughout 120-h post-infection at a single dose of 8 mg/kg (p < 0.05). In conclusion, this study provides a reference for the transformation of cecropin to derive small peptides and presents C18 as an attractive therapeutic candidate to be developed to treat severe MRSA infections. Full article

(This article belongs to the Special Issue Mechanisms of Antimicrobial Peptides on Pathogens)

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21 pages, 4483 KiB

Open AccessArticle

Powerful Antibacterial Peptides from Egg Albumin Hydrolysates

by Abdul-Raouf Al-Mohammadi, Ali Osman, Gamal Enan, Seham Abdel-Shafi, Mona El-Nemer, Mahmoud Sitohy and Mohamed A. Taha

Antibiotics 2020, 9(12), 901; https://doi.org/10.3390/antibiotics9120901 - 13 Dec 2020

Cited by 21 | Viewed by 3243

Abstract

Native egg albumin (NEA) was isolated from hen eggs and hydrolyzed by pepsin to produce hydrolyzed egg albumin (HEA). HEA was chemically characterized and screened for its antibacterial activity against 10 pathogenic bacteria (6 Gram (+) and 4 Gram (−)). The SDS-PAGE pattern of NEA showed molecular weights of hen egg albumin subunits ranging from 30 to 180 kDa. The highest intensive bands appeared at a molecular mass of about 50 and 97 kDa. Ultra-performance liquid chromatography (UPLC) of the peptic HEA revealed 44 peptides, 17 of them were dipeptides, and the other 27 fractions corresponded to bigger peptides (3–9 amino acids). The dipeptides and big peptides represented 26% and 74% of the total hydrolysate, respectively. The MIC of HEA was about 100 μg/L for Listeria monocytogenes, Bacillus cereus, Staphylococcus aureus, Salmonella typhimurium, Streptococcus pyogenes, and Klebsiella oxytoca and 150 μg/L for Pseudomonas aeruginosa, Bacillus subtilis, and Listeria ivanovii and 200 μg/L for Escherichia coli. L. monocytogenes was the most sensitive organism to HEA. Mixtures of HEA with antibiotics showed more significant antibacterial activity than individually using them. Transmission electron microscopy (TEM) revealed various signs of cellular deformation in the protein-treated bacteria. HEA may electrostatically and hydrophobically interact with the cell wall and cell membrane of the susceptible bacteria, engendering large pores and pore channels leading to cell wall and cell membrane disintegration. Higher cell permeability may, thus, occur, leading to cell emptiness, lysis, and finally death. Alternatively, no toxicity signs appeared when HEA was administrated to Wistar Albino rats as one single dose (2000, 5000 mg/kg body weight) or repeated daily dose (500 and 2500 mg/kg body weight/day) for 28 days to disclose the possible toxicity hazards. HEA did not produce any death. Full article

(This article belongs to the Special Issue Mechanisms of Antimicrobial Peptides on Pathogens)

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Other

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9 pages, 416 KiB

Open AccessPerspective

Synthetic Antimicrobial Immunomodulatory Peptides: Ongoing Studies and Clinical Trials

by Małgorzata Lesiuk, Małgorzata Paduszyńska and Katarzyna E. Greber

Antibiotics 2022, 11(8), 1062; https://doi.org/10.3390/antibiotics11081062 - 05 Aug 2022

Cited by 10 | Viewed by 2035

Abstract

The increasingly widespread antimicrobial resistance forces the search for new antimicrobial substances capable of fighting infection. Antimicrobial peptides (AMPs) and their synthetic analogs form an extensive group of compounds of great structural diversity and multifunctionality, different modes of antimicrobial action, and considerable market potential. Some AMPs, in addition to their proven antibacterial, antifungal, and antiviral activity, also demonstrate anti-inflammatory and immunomodulatory capabilities; these are called innate defense regulator (IDR) peptides. IDR peptides stimulate or inhibit the body’s immune system, e.g., by stimulating leukocyte migration to the site of infection, driving macrophage differentiation and activation, providing chemotactic action for neutrophils, degranulation and activation of mast cells, altering chemokine and cytokine production, and even induction of angiogenesis and wound healing. Such multifunctional immunomodulatory peptide molecules are currently being investigated and developed. Exploring and utilizing IDR peptides as an indirect weapon against infectious diseases could represent a completely new strategy to cope with the issue of antimicrobial resistance. Full article

(This article belongs to the Special Issue Mechanisms of Antimicrobial Peptides on Pathogens)

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