Search results for "ANTIMICROBIAL PEPTIDES"

(19)F NMR screening of unrelated antimicrobial peptides shows that membrane interactions are largely governed by lipids.

2014

AbstractMany amphiphilic antimicrobial peptides permeabilize bacterial membranes via successive steps of binding, re-alignment and/or oligomerization. Here, we have systematically compared the lipid interactions of two structurally unrelated peptides: the cyclic β-pleated gramicidin S (GS), and the α-helical PGLa. 19F NMR was used to screen their molecular alignment in various model membranes over a wide range of temperatures. Both peptides were found to respond to the phase state and composition of these different samples in a similar way. In phosphatidylcholines, both peptides first bind to the bilayer surface. Above a certain threshold concentration they can re-align and immerse more dee…

A Novel Peptide with Antifungal Activity from Red Swamp Crayfish Procambarus clarkii

2022

The defense system of freshwater crayfish Procambarus clarkii as a diversified source of bioactive molecules with antimicrobial properties was studied. Antimicrobial activity of two polypeptide-enriched extracts obtained from hemocytes and hemolymph of P. clarkii were assessed against Gram positive (Staphylococcus aureus, Enterococcus faecalis) and Gram negative (Pseudomonas aeruginosa, Escherichia coli) bacteria and toward the yeast Candida albicans. The two peptide fractions showed interesting MIC values (ranging from 11 to 700 μg/mL) against all tested pathogens. Polypeptide-enriched extracts were further investigated using a high-resolution mass spectrometry and database search and 14 n…

Study of the cwaRS-ldcA Operon Coding a Two-Component System and a Putative L,D-Carboxypeptidase in Lactobacillus paracasei

2020

International audience; The cell surface is the primary recognition site between the bacterium and the host. An operon of three genes, LSEI_0219 (cwaR), LSEI_0220 (cwaS), and LSEI_0221 (ldcA), has been previously identified as required for the establishment of Lactobacillus paracasei in the gut. The genes cwaR and cwaS encode a predicted two-component system (TCS) and ldcA a predicted D-alanyl-D-alanine carboxypeptidase which is a peptidoglycan (PG) biosynthesis enzyme. We explored the functionality and the physiological role of these three genes, particularly their impact on the bacterial cell wall architecture and on the bacterial adaptation to environmental perturbations in the gut. The …

A peptide from human β thymosin as a platform for the development of new anti-biofilm agents for Staphylococcus spp. and Pseudomonas aeruginosa

2016

Conventional antibiotics might fail in the treatment of biofilm-associated infections causing infection recurrence and chronicity. The search for antimicrobial peptides has been performed with the aim to discover novel anti-infective agents active on pathogens in both planktonic and biofilm associated forms. The fragment 9-19 of human thymosin β4 was studied through 1 μs MD simulation. Two main conformations of the peptide were detected, both constituted by a central hydrophobic core and by the presence of peripheral charged residues suggesting a possible mechanism of interaction with two models of biological membranes, related to eukaryotic or bacterial membrane respectively. In addition, …

Recent findings on phenoloxidase activity and antimicrobial activity of hemocyanins

2003

Antimicrobial Peptides and Their Superior Fluorinated Analogues: Structure-Activity Relationships as Revealed by NMR Spectroscopy and MD Calculations

2010

9 pag., 6 fig, 3 tab.

Established cotton stainer gut bacterial mutualists evade regulation by host antimicrobial peptides

2019

Symbioses with microorganisms are ubiquitous in nature and confer important ecological traits to animal hosts but also require control mechanisms to ensure homeostasis of the symbiotic interactions. In addition to protecting hosts against pathogens, animal immune systems recognize, respond to, and regulate mutualists. The gut bacterial symbionts of the cotton stainer bug, Dysdercus fasciatus, elicit an immune response characterized by the upregulation of c-type lysozyme and the antimicrobial peptide pyrrhocoricin in bugs with their native gut microbiota compared to that in dysbiotic insects. In this study, we investigated the impact of the elicited antimicrobial immune response on the estab…

Peptidomimetics – An infinite reservoir of metal binding motifs in metabolically stable and biologically active molecules

2020

The involvement of metal ions in interactions with therapeutic peptides is inevitable. They are one of the factors able to fine-tune the biological properties of antimicrobial peptides, a promising group of drugs with one large drawback - a problematic metabolic stability. Appropriately chosen, proteolytically stable peptidomimetics seem to be a reasonable solution of the problem, and the use of D-, β-, γ-amino acids, unnatural amino acids, azapeptides, peptoids, cyclopeptides and dehydropeptides is an infinite reservoir of metal binding motifs in metabolically stable, well-designed, biologically active molecules. Below, their specific structural features, metal-chelating abilities and anti…

Inactivation of an Enveloped Virus by Immobilized Antimicrobial Peptides.

2021

Infections caused by viruses are difficult to treat due to their life cycle, which depends on the replication machinery of the respective host cells. Commonly used antiviral strategies are based upon the application of, e.g., entry inhibitors and other compounds that interfere with virus replication. Besides possible side effects, the rapid occurrence of viral resistance poses a great challenge. Antimicrobial peptides (AMPs), as a component of the innate immunity, are able to kill bacteria and fungi and, in addition, may inactivate enveloped viruses. Many AMPs exert their biological function by impairing microbial and viral membranes. As a result, membrane integrity is lost, leading to bact…

Zn-Enhanced Asp-Rich Antimicrobial Peptides N-Terminal Coordination by Zn(II) and Cu(II), Which Distinguishes Cu(II) Binding to Different Peptides

2021

The antimicrobial activity of surfactant-associated anionic peptides (SAAPs), which are isolated from the ovine pulmonary surfactant and are selective against the ovine pathogen Mannheimia haemolytica, is strongly enhanced in the presence of Zn(II) ions. Both calorimetry and ITC measurements show that the unique Asp-only peptide SAAP3 (DDDDDDD) and its analogs SAAP2 (GDDDDDD) and SAAP6 (GADDDDD) have a similar micromolar affinity for Zn(II), which binds to the N-terminal amine and Asp carboxylates in a net entropically-driven process. All three peptides also bind Cu(II) with a net entropically-driven process but with higher affinity than they bind Zn(II) and coordination that involves the N…