Search results for "Antimicrobial peptides"
showing 10 items of 76 documents
Antimicrobial peptides from echinoderms as antibiofilm agents: a natural strategy to combat bacterial infections
2014
AbstractIncreased attention has been focused on marine invertebrates as a source of bioactive molecules for biomedical applications. Many bioactive molecules are part of the innate immune system. Some more recently isolated compounds, mainly from the sea urchin and the sea cucumber, are antimicrobial peptides (AMPs) active against Gram-positive and Gram-negative bacteria, and fungi. In this review we described the most recent studies on AMPs isolated from echinoderms. AMPs are small peptides (< 10 kDa) with cationic charge and amphipathic structure. Recently, it was demonstrated that in the coelomocyte lysates of Paracentrotus lividus and Holothuria tubulosa, AMPs possess activity against s…
The LuxR Regulators PcoR and RfiA Co-regulate Antimicrobial Peptide and Alginate Production in Pseudomonas corrugata
2018
Cyclic lipopeptides (CLPs) are considered as some of the most important secondary metabolites in different plant-associated bacteria, thanks to their antimicrobial, cytotoxic, and surfactant properties. In this study, our aim was to investigate the role of the Quorum Sensing (QS) system, PcoI/PcoR, and the LuxR-type transcriptional regulator RfiA in CLP production in the phytopatogenic bacterium, Pseudomonas corrugata based on our previous work where we reported that the pcoR and rfiA mutants were devoid of the CLPs cormycin and corpeptin production. Due to the close genetic link between the QS system and the RfiA (rfiA is co-transcribed with pcoI), it was difficult to ascertain the specifi…
Antimicrobial and antistaphylococcal biofilm activity from the sea urchin Paracentrotus lividus
2010
Aims: Staphylococcal biofilm-associated infections are resistant to conventional antibiotics. Consequently, new agents are needed to treat them. With this aim, we focused on the effector cells (coelomocytes) of the sea urchin Paracentrotus lividus immune system. Methods and Results: We tested the activity of the 5-kDa peptide fraction of the cytosol from coelomocytes (5-CC) against a group of Gram-positive, Gram-negative bacteria and fungi. We determined minimal inhibitory concentrations (MICs) ranging from 253·7 to 15·8 mg ml−1. We observed an inhibitory activity and antibiofilm properties of 5-CC against staphylococcal biofilms of reference strains Staphylococcus epidermidis DSM 3269 an…
Echinoderm Antimicrobial Peptides
2016
Abstract Antimicrobial peptides (AMPs) are widely expressed in organisms and have been linked to innate and acquired immunity in vertebrates. These compounds are constitutively expressed from different cellular types to interact directly with infectious agents and/or modulate immunoreactions. In invertebrates, including echinoderms, which lack a vertebrate-type adaptive immune system, AMPs represent the major humoral defense system against infection, showing a diverse spectrum of action mechanisms, most of them related to plasma membrane disturbance and lethal alteration of microbial integrity. Here, we summarize the knowledge of AMPs in echinoderms as Strongylocins identified in the sea ur…
Temporal patterns in immune responses to a range of microbial insults (Tenebrio molitor).
2008
8 pages; International audience; Much work has elucidated the pathways and mechanisms involved in the production of insect immune effector systems. However, the temporal nature of these responses with respect to different immune insults is less well understood. This study investigated the magnitude and temporal variation in phenoloxidase and antimicrobial activity in the mealworm beetle Tenebrio molitor in response to a number of different synthetic and real immune elicitors. We found that antimicrobial activity in haemolymph increased rapidly during the first 48h after a challenge and was maintained at high levels for at least 14 days. There was no difference in the magnitude of responses …
Bacterial biofilms: a challenge in the discovery of new anti-infective agents.
2010
The ability to form a biofilm, bacterial communities able to grow on surfaces and surrounded by an extracellular polymeric substance biofilm agents.Our research group focused on discovering of novel chemical agents of potential therapeutic utility in the treatment of staphylococcal biofilm-associatedinfections by screening novel compounds (synthetic or natural). In a recent study, the antistaphylococcalbiofilm activity of pyrrolomycins C,D, F1, F2a, F2b, F3 a family of halogenated pyrroles which are naturally produced byActinosporangium vitaminophylum and of the synthesized related compounds I, II, III were investigated and compared (Schillaci et al, 2010). We also focused on marine inverte…
Fragments of β-thymosin from the sea urchin Paracentrotus lividus as potential antimicrobial peptides against staphylococcal biofilms.
2012
The immune mediators in echinoderms can be a potential source of novel antimicrobial peptides (AMPs) applied toward controlling pathogenic staphylococcal biofilms that are intrinsically resistant to conventional antibiotics. The peptide fraction5 kDa from the cytosol of coelomocytes of the sea urchin Paracentrotus lividus (5-CC) was tested against a group of Gram-positive and Gram-negative pathogen reference strains. The 5-CC of P. lividus was active against all planktonic-tested strains but also showed antibiofilm properties against staphylococcal strains. Additionally, we demonstrated the presence of three small peptides in the 5-CC belonging to segment 9-41 of a P. lividusβ-thymosin. The…
Microbiome symbionts and diet diversity incur costs on the immune system of insect larvae
2017
Communities of symbiotic microorganisms that colonize the gastrointestinal tract play an important role in food digestion and protection against opportunistic microbes. Diet diversity increases the number of symbionts in the intestines, a benefit that is considered to impose no cost for the host organism. However, less is known about the possible immunological investments that hosts have to make in order to control the infections caused by symbiont populations that increase due to diet diversity. By using taxonomical composition analysis of the 16S rRNA V3 region, we show that Enterococci are the dominating group of bacteria in the midgut of the larvae of the greater wax moth (Galleria mell…
FRAGMENTS OF BETA-THYMOSIN FROM THE SEA-URCHIN PARACENTROTUS LIVIDUS AS NOVEL ANTIMICROBIAL PEPTIDES AGAINST STAPHYLOCOCCAL BIOFILMS
2012
With the aim to face the threat of pathogen biofilms intrinsically resistant to conventional antibiotics, we focused on coelomocytes, the immune mediators in echinoderms, as source of novel antimicrobial peptides (AMPs). The proteic fraction <5kDa from coelomocytes cytosol of the sea-urchin Paracentrotus lividus (5-CC) was tested against a group of Gram positive and Gram negative pathogen reference strains. The 5-CC of P. lividus resulted active against all tested strains at concentrations ranging from 15.8 to 253.7 mg/mL. The ability to prevent staphylococcal biofilm formation was evaluated against the biofilm of clinical strain S.epidermidis 1457 using live/dead staining in combination wi…
Stabilisation of mixed peptide/lipid complexes in selective antifungal hexapeptides
2004
AbstractThe design of antimicrobial peptides could have benefited from structural studies of known peptides having specific activity against targetmicrobes, but not toward other microorganisms. We have previously reported the identification of a series of peptides (PAF-series) activeagainst certain postharvest fungal phytopathogens, and devoid of toxicity towards E. coli and S. cerevisiae [Lo´pez-Garci´a et al. Appl.Environ. Microbiol. 68 (2002) 2453]. The peptides inhibited the conidia germination and hyphal growth. Here, we present a comparativestructural characterisation of selected PAF peptides obtained by single-amino-acid replacement, which differ in biological activity. Thepeptides w…