Antimicrobial Activity and Mechanisms of Action of Peptides

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

Deadline for manuscript submissions: closed (30 June 2023) | Viewed by 6268

Special Issue Editor


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Guest Editor
Department of Medicine and Surgery, Laboratory of Microbiology and Virology, University of Parma, Parma, Italy
Interests: antimicrobial peptides; serum protein-derived peptides; infectious diseases; anti-infective peptides; anti-biofilm peptides; structure-function relationship of AMP

Special Issue Information

Dear Colleagues,

in the landscape of the growing emergence of drug resistance among pathogens, antimicrobial peptides (AMPs) appear as valuable candidates for the development of a new generation of therapeutic agents intended to replace or supplement conventional antimicrobial drugs.

In fact, AMPs are active against different classes of pathogens, including multidrug-resistant microorganisms, and they do not easily induce resistance, while in many cases showing little or no toxicity toward human cells. New delivery strategies and chemical structure optimization, together with improvement in chemical synthesis procedures, will possibly overcome known limitations related to pharmacokinetics and costs of production of AMPs.

To date, a plethora of natural and synthetic AMPs has been identified with the ability to exert a direct action on pathogens (i.e., killing of microorganisms or inhibition of viral replication) or to indirectly promote the resolution of the infection through immunomodulatory effects. AMPs with wound healing properties have been also described.

These AMPs present an assortment of structures ranging from helical to β-strand, mixed, or random coil, which may account for diverse mechanisms of action. Other characteristics such as charge, hydrophobicity, amphipathicity, and peptide length have been shown to be responsible for modulating the anti-infective mechanism of AMPs.

This Special Issue aims to gather contributions which may promote a better understanding of the structure–function relationship, mechanism of action, and possible biomedical applications of AMPs. Submissions on the discovery of new AMPs or novel activities of already known AMPs are also encouraged.

All submission types, including original research articles, short communications, and comprehensive reviews, are welcome.

Dr. Laura Giovati
Guest Editor

Manuscript Submission Information

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Keywords

  • antimicrobial peptides
  • mechanisms of AMP
  • antimicrobial activity
  • antiviral activity
  • host immunity modulation
  • wound healing
  • biomedical application

Published Papers (4 papers)

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Research

15 pages, 2510 KiB  
Article
Antimicrobial Properties and Mode of Action of Cryptdin-4, a Mouse α-Defensin Regulated by Peptide Redox Structures and Bacterial Cultivation Conditions
by Yi Wang, Yuchi Song, Shaonan Yan, Rina Hiramine, Yuki Ohnishi, Yuki Yokoi, Kiminori Nakamura, Takashi Kikukawa, Tokiyoshi Ayabe and Tomoyasu Aizawa
Antibiotics 2023, 12(6), 1047; https://doi.org/10.3390/antibiotics12061047 - 14 Jun 2023
Viewed by 1247
Abstract
Cryptdin-4 (crp4) is an enteric α-defensin derived from mice, and is a main mediator of immunity to oral infections and a determinant of the composition of the intestinal microbiota. Structurally, crp4 exists in two states: the oxidized form (crp4oxi), constrained by three invariant [...] Read more.
Cryptdin-4 (crp4) is an enteric α-defensin derived from mice, and is a main mediator of immunity to oral infections and a determinant of the composition of the intestinal microbiota. Structurally, crp4 exists in two states: the oxidized form (crp4oxi), constrained by three invariant disulfide bonds, and the reduced form (crp4red) with six free thiol groups, both of which exist in the intestinal tract. In this study, the antibacterial mechanisms of crp4 in both forms under aerobic and anaerobic conditions were investigated using Escherichia coli (E. coli), an anaerobic facultative bacterium, as a model. Fluorescent dye studies revealed that both crp4oxi and crp4red exhibited antimicrobial activity against cells cultured under aerobic conditions via rapid membrane depolarization. Furthermore, the antioxidant treatment experiments suggested that only crp4oxi exhibited antimicrobial activity by the induction and accumulation of reactive oxygen species (ROS). However, under anaerobic culture conditions, the ability of both forms to disrupt the function of bacterial membranes decreased and activity was greatly reduced, but crp4red maintained some antimicrobial activity. This activity may be due to the inhibition of intracellular functions by DNA binding. Altogether, these data indicate that, according to its redox structure and the environmental redox conditions, crp4 could perform different antimicrobial activities via different mechanisms. Full article
(This article belongs to the Special Issue Antimicrobial Activity and Mechanisms of Action of Peptides)
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16 pages, 3989 KiB  
Article
Novel Arginine- and Proline-Rich Candidacidal Peptides Obtained through a Bioinformatic Approach
by Tecla Ciociola, Laura Giovati, Tiziano De Simone, Greta Bergamaschi, Alessandro Gori, Valerio Consalvi, Stefania Conti and Alberto Vitali
Antibiotics 2023, 12(3), 472; https://doi.org/10.3390/antibiotics12030472 - 26 Feb 2023
Cited by 2 | Viewed by 1680
Abstract
Antimicrobial resistance is a major public health concern worldwide. Albeit to a lesser extent than bacteria, fungi are also becoming increasingly resistant to antifungal drugs. Moreover, due to the small number of antifungal classes, therapy options are limited, complicating the clinical management of [...] Read more.
Antimicrobial resistance is a major public health concern worldwide. Albeit to a lesser extent than bacteria, fungi are also becoming increasingly resistant to antifungal drugs. Moreover, due to the small number of antifungal classes, therapy options are limited, complicating the clinical management of mycoses. In this view, antimicrobial peptides (AMPs) are a potential alternative to conventional drugs. Among these, Proline-rich antimicrobial peptides (PrAMPs), almost exclusively of animal origins, are of particular interest due to their peculiar mode of action. In this study, a search for new arginine- and proline-rich peptides from plants has been carried out with a bioinformatic approach by sequence alignment and antimicrobial prediction tools. Two peptide candidates were tested against planktonic cells and biofilms of Candida albicans and Candida glabrata strains, including resistant isolates. These peptides showed similar potent activity, with half-maximal effective concentration values in the micromolar range. In addition, some structural and functional features, revealing peculiar mechanistic behaviors, were investigated. Full article
(This article belongs to the Special Issue Antimicrobial Activity and Mechanisms of Action of Peptides)
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13 pages, 1946 KiB  
Article
Oligopeptide Sortase Inhibitor Modulates Staphylococcus aureus Cell Adhesion and Biofilm Formation
by Svetlana A. Bozhkova, Ekaterina M. Gordina, Dmitry V. Labutin and Konstantin V. Kudryavtsev
Antibiotics 2022, 11(12), 1836; https://doi.org/10.3390/antibiotics11121836 - 17 Dec 2022
Cited by 3 | Viewed by 1287
Abstract
Prevention of bacterial adhesion is one of the most important antivirulence strategies for meeting the global challenge posed by antimicrobial resistance. We aimed to investigate the influence of a peptidic S. aureus sortase A inhibitor on bacterial adhesion to eukaryotic cells and biofilm [...] Read more.
Prevention of bacterial adhesion is one of the most important antivirulence strategies for meeting the global challenge posed by antimicrobial resistance. We aimed to investigate the influence of a peptidic S. aureus sortase A inhibitor on bacterial adhesion to eukaryotic cells and biofilm formation as a potential method for reducing S. aureus virulence. The pentapeptide LPRDA was synthesized and characterized as a pure individual organic compound. Incubation of MSSA and MRSA strains with LPRDA induced a subsequent reduction in staphylococcal adhesion to Vero cells and biofilm formation, as visualized by microscopic and spectrophotometric methods, respectively. LPRDA did not have a cytotoxic effect on eukaryotic or bacterial cells. The pentapeptide LPRDA deserves further investigation using in vitro and in vivo models of Gram-positive bacteriemia as a potential antibacterial agent with an antiadhesive mechanism of action. Full article
(This article belongs to the Special Issue Antimicrobial Activity and Mechanisms of Action of Peptides)
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14 pages, 5468 KiB  
Article
Dual Roles of Extracellular Histone H3 in Host Defense: Its Differential Regions Responsible for Antimicrobial and Cytotoxic Properties and Their Modes of Action
by Yuri Tanaka, Nanako Yamanaka, Izumi Koyano, Itaru Hasunuma, Tetsuya Kobayashi, Sakae Kikuyama and Shawichi Iwamuro
Antibiotics 2022, 11(9), 1240; https://doi.org/10.3390/antibiotics11091240 - 13 Sep 2022
Cited by 4 | Viewed by 1495
Abstract
Extracellular histones play a dual role—antimicrobial and cytotoxic—in host defense. In this study, we evaluated the antimicrobial and cytotoxic activities of histone H3 and identified the responsible molecular regions for these properties. Broth microdilution assays indicated that histone H3 exhibits growth inhibitory activity [...] Read more.
Extracellular histones play a dual role—antimicrobial and cytotoxic—in host defense. In this study, we evaluated the antimicrobial and cytotoxic activities of histone H3 and identified the responsible molecular regions for these properties. Broth microdilution assays indicated that histone H3 exhibits growth inhibitory activity against not only Gram-negative and -positive bacteria but also fungi. Observations under scanning electron microscopy (SEM) revealed that histone H3 induced morphological abnormalities on the cell surface of a wide range of reference pathogens. MTT assays and SEM observations indicated that histone H3 has strong cytotoxic and cell lytic effects on mammalian normal, immortal, and tumor cell lines. Assays using synthetic peptides corresponding to fragments 1–34 (H3DP1), 35–68 (H3DP2), 69–102 (H3DP3), and 103–135 (H3DP4) of histone H3 molecule demonstrated that its antimicrobial activity and cytotoxicity are elicited by the H3DP2 and H3DP3 protein regions, respectively. Enzyme-linked endotoxin binding assays indicated that histones H3 and H3DP1, H3DP2, and H3DP4, but not H3DP3, exhibited high affinities toward lipopolysaccharide and lipoteichoic acid. Our findings are expected to contribute to the development of new histone H3-based peptide antibiotics that are not cytotoxic. Full article
(This article belongs to the Special Issue Antimicrobial Activity and Mechanisms of Action of Peptides)
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