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8.3
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Journals
Biomolecules
Special Issues
Structure and Function of Antimicrobial Peptides
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Structure and Function of Antimicrobial Peptides

A special issue of Biomolecules (ISSN 2218-273X).

Deadline for manuscript submissions: closed (28 October 2019) | Viewed by 11696

Special Issue Editors

Prof. Dr. Kornelius Zeth

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Guest Editor
Department for Science and Environment, Roskilde University, 4000 Roskilde, Denmark
Interests: recombinant protein expression; protein structure; protein biochemistry; molecular biology; microbiology; biochemistry; nanobiotechnology; crystal structure; crystallization; microscopy
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Håvard Jenssen

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Guest Editor
Department for Science and Environment, Roskilde Universitetscenter, 4000 Roskilde, Denmark
Interests: antimicrobial peptides; membrane proteins; structural biology; protein X-ray crystallography
Prof. Dr. Enea Sancho-Vaello

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Guest Editor
Institute of Microbiology and Infection, University of Birmingham, Birmingham B15 2TT, UK
Interests: antimicrobial peptides; membrane proteins; structural biology; protein X-ray crystallography; efflux pumps
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The increase in antibiotic resistance is one of the biggest health challenges our society is facing. As a consequence, the discovery of new antibiotic lead structures from all sources, including antimicrobial peptides (AMPs), is urgent. According to many recent studies, AMPs have the potential to effectively eradicate pathogenic bacteria and biofilms, and hence the potential to serve as another class of new antibiotics. However, in spite of the large number of peptides, only a minor fraction was introduced into clinical studies, and none of these is on the pharmaceutical market as new antibiotics. This is, in part, a consequence of the insufficient understanding of the mechanisms of how individual AMPs target and kill bacterial cells, and hence the rational basis for the design of new AMPs with tailored properties is impeded. Therefore, more AMP structures, ideally in complex with their cellular targets, are needed in order to track their pathways and interfaces with AMP/target-complexes so as to specifically enhance their properties.

The aim of this Special Issue is to combine the most recent developments in the structural biology, biophysics, biochemistry, and microbiology of antimicrobial peptides, focusing on a small selection of representative AMPs. This assembled information is used to reconsider the current repertoire of the three main basic AMP targeting mechanisms of bacterial cell membranes (the barrel stave model, the carpet model, and the toroidal model). The combination of the structures and functions assembled here will guide towards the architectural principles of AMPs, and give hints as to their particular mechanism targeting the molecules of the bacterial cell wall or cytoplasm, respectively. The collected information will show the diversity of molecular targets at the bacterial cell wall of Gram-positive and -negative bacteria, and will help explain why AMPs, in spite of their long evolution in the presence of bacteria, have maintained their significant activity by targeting, for example, the cytoplasmic membrane—the Achilles’ heel of the cell. Finally, the structures and functions will be used to re-formulate the three membrane-centered basic models by adding the most recent structural and functional information in order to ultimately furnish a set of new and enhanced mechanistic models, which can be used as a basis for the discussion of AMPs in future literature.

Dr. Kornelius Zeth
Dr. Håvard Jenssen
Dr. Enea Sancho-Vaello
Guest Editors

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. Biomolecules 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 2700 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
  • Function
  • Structure
  • Assembly
  • Fibrils, fibers, and amyloids
  • Functional models
  • Modelling
  • Mode of action
  • NMR and X-ray

Published Papers (3 papers)

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Research

23 pages, 4983 KiB  
Article
Temporin-SHa and Its Analogs as Potential Candidates for the Treatment of Helicobacter pylori
by Hamza Olleik, Elias Baydoun, Josette Perrier, Akram Hijazi, Josette Raymond, Marine Manzoni, Lucas Dupuis, Ghislain Pauleau, Yvain Goudard, Bruno de La Villéon, Géraldine Goin, Philippe Sockeel, Muhammad Iqbal Choudhary, Eric Di Pasquale, Muhammad Nadeem-ul-Haque, Hunain Ali, Arif Iftikhar Khan, Farzana Shaheen and Marc Maresca
Biomolecules 2019, 9(10), 598; https://doi.org/10.3390/biom9100598 - 11 Oct 2019
Cited by 11 | Viewed by 4926
Abstract
Helicobacterpylori is one of the most prevalent pathogens colonizing 50% of the world’s population and causing gastritis and gastric cancer. Even with triple and quadruple antibiotic therapies, H. pylori shows increased prevalence of resistance to conventional antibiotics and treatment failure. Due to [...] Read more.
Helicobacterpylori is one of the most prevalent pathogens colonizing 50% of the world’s population and causing gastritis and gastric cancer. Even with triple and quadruple antibiotic therapies, H. pylori shows increased prevalence of resistance to conventional antibiotics and treatment failure. Due to their pore-forming activity, antimicrobial peptides (AMP) are considered as a good alternative to conventional antibiotics, particularly in the case of resistant bacteria. In this study, temporin-SHa (a frog AMP) and its analogs obtained by Gly to Ala substitutions were tested against H. pylori. Results showed differences in the antibacterial activity and toxicity of the peptides in relation to the number and position of D-Ala substitution. Temporin-SHa and its analog NST1 were identified as the best molecules, both peptides being active on clinical resistant strains, killing 90–100% of bacteria in less than 1 h and showing low to no toxicity against human gastric cells and tissue. Importantly, the presence of gastric mucins did not prevent the antibacterial effect of temporin-SHa and NST1, NST1 being in addition resistant to pepsin. Taken together, our results demonstrated that temporin-SHa and its analog NST1 could be considered as potential candidates to treat H. pylori, particularly in the case of resistant strains. Full article
(This article belongs to the Special Issue Structure and Function of Antimicrobial Peptides)
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15 pages, 1825 KiB  
Article
Immunomodulatory Functions of the Human Cathelicidin LL-37 (aa 13–31)-Derived Peptides are Associated with Predicted α-Helical Propensity and Hydrophobic Index
by Mahadevappa Hemshekhar, Sana Faiyaz, Ka-Yee Grace Choi, Oleg V. Krokhin and Neeloffer Mookherjee
Biomolecules 2019, 9(9), 501; https://doi.org/10.3390/biom9090501 - 18 Sep 2019
Cited by 11 | Viewed by 2978
Abstract
The anti-endotoxin activity of the cationic peptide LL-37 and its derivative IG-19 is attributed to electrostatic interaction of the peptides’ positive charge with negatively charged bacterial lipopolysaccharides (LPS), and in part to the alteration of intracellular mechanisms independent of peptide binding to LPS. [...] Read more.
The anti-endotoxin activity of the cationic peptide LL-37 and its derivative IG-19 is attributed to electrostatic interaction of the peptides’ positive charge with negatively charged bacterial lipopolysaccharides (LPS), and in part to the alteration of intracellular mechanisms independent of peptide binding to LPS. We examined the immunomodulatory responses induced by IG-19 and four IG-19-derived scrambled peptides (IG-19a–d), in the presence and absence of LPS, in macrophages and peripheral blood-derived mononuclear cells. All peptides had identical net charge (+5) and amino acid composition, but different hydrophobicity and α-helical propensity. Peptide IG-19 suppressed LPS-induced cytokine/chemokine production by >90%, IG-19a and IG-19b suppressed it by 40–50%, and IG-19c and IG-19d did not suppress cytokine/chemokine production at all. In silico prediction algorithms and the peptide retention time (RT) on a C18 RP HPLC column indicated a linear association between α-helical propensity and hydrophobicity with the ability of the peptides to inhibit LPS-induced responses. Peptide RT exhibited a significant correlation (>70%) between the suppression of LPS-induced cytokine/chemokine production and peptide-induced production of the anti-inflammatory cytokine IL-1RA. These results indicate that RT on a C18 column can be used as a predictor for the immunomodulatory functions of cationic peptides. Overall, we demonstrated that the immunomodulatory functions of LL-37-derived peptides with identical positive charge and amino acid composition are directly associated with the predicted α-helical propensity and hydrophobicity of the peptides. Full article
(This article belongs to the Special Issue Structure and Function of Antimicrobial Peptides)
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13 pages, 1748 KiB  
Article
Sulfated Glycoaminoglycans and Proteoglycan Syndecan-4 Are Involved in Membrane Fixation of LL-37 and Its Pro-Migratory Effect in Breast Cancer Cells
by Chahrazed Habes, Günther Weber and Caroline Goupille
Biomolecules 2019, 9(9), 481; https://doi.org/10.3390/biom9090481 - 12 Sep 2019
Cited by 20 | Viewed by 3140
Abstract
Initially characterized by its antimicrobial activities, LL-37 has also been shown to significantly contribute to tumor development. On breast cancer cell lines, LL-37 increases intracellular calcium via the TRPV2 channel and their migration via the activation of PI3K/AKT signaling. Its all-d enantiomer [...] Read more.
Initially characterized by its antimicrobial activities, LL-37 has also been shown to significantly contribute to tumor development. On breast cancer cell lines, LL-37 increases intracellular calcium via the TRPV2 channel and their migration via the activation of PI3K/AKT signaling. Its all-d enantiomer d-LL-37 induces similar effects, which excludes a protein-protein interaction of LL-37 in a classic ligand-receptor manner. Its net charge of +6 gave rise to the hypothesis that the peptide uses the negative charges of sulfoglycans or sialic acids to facilitate its attachment to the cell membrane and to induce its activities. Whereas several vegetal lectins, specifically attaching to sialylated or sulfated structures, blocked the activities of LL-37 on both calcium increase and cell migration, several sialidases had no effect. However, the competitive use of free sulfated glycoaminoglycans (GAGs) as chrondroitin and heparin, or treatment of the cell surface with chondroitinase and heparinase resulted in an activity loss of 50–100% for LL-37. Concordant results were obtained by blocking the synthesis of GAGs with 4-Methylumbelliferyl-β-d-xyloside, and by suppression of glycan sulfatation by sodium chlorate. Using a candidate approach by suppressing proteoglycan synthesis using RNA interference, syndecan-4 was shown to be required for the activities of LL-37 and its binding to the cell surface. This leads to the conclusion that syndecan-4, by means of sulfated GAGs, could act as a receptor for LL-37. Full article
(This article belongs to the Special Issue Structure and Function of Antimicrobial Peptides)
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