1,721,123 research outputs found
Short native antimicrobial peptides and engineered ultrashort lipopeptides: similarities and differences in cell specificities and modes of action
No full textDue to the rapid emergence of resistant microbes to the currently available antibiotics, cationic antimicrobial peptides have attracted considerable interest as a possible new generation of anti-infective compounds. However, low cost development for therapeutic or industrial purposes requires, among other properties, that the peptides will be small and with simple structure. Therefore, considerable research has been devoted to optimizing peptide length combined with a simple design. This review focuses on the similarities and differences in the mode of action and target cell specificity of two families of small peptides: the naturally occurring temporins from the skin of amphibia and the engineered ultrashort lipopeptides. We will also discuss the finding that acylation of cationic peptides results in molecules with a more potent spectrum of activity and a higher resistance to proteolytic degradation. Conjugation of fatty acids to linear native peptide sequences is a powerful strategy to engineer novel successful anti-infective drugs
Current development of analytical affinity chromatography: Design and biotechnological uses of molecular recognition surfaces
No full textAnalytical high performance liquid affinity chromatography (analytical HPLAC) has been investigated as an experimental guide to both synthetic design and affinity technological use of peptide and protein recognition surfaces. This work has progressed from the ongoing use of analytical affinity chromatography to study interaction mechanisms of naturally-occurring peptides and proteins, including enzyme fragment complexes and neuroendocrine biosynthetic precursors. We recently initiated a study to use analytical HPLAC for de novo design of recognition peptides called “anti-sense peptides”. Present data suggest the potential to use anti-sense peptides as “synthetic antibodies”, in immobilized forms, for biomolecular separation and analysis. Analogous studies have been started with immobilized natural antibodies in analytical immuno HPLAC. Our present data typify the growing usefulness of analytical HPLAC when designing recognition molecules, analyzing their interaction characteristics, and devising ways to use them in affinity technology
Mode of action of the antimicrobial peptide Bombinin H2 and its natural single D-amino acid diastereomer, on Leishmania parasites and model membranes
No full textLeishmaniasis encompasses a wide range of infections caused by the human parasitic protozoan species belonging to the Leishmania genus. It appears frequently as an opportunistic disease, especially in virus-infected immunodepressed people. Similarly to other pathogens, parasites became resistant to most of first-line drugs. Therefore, there is an urgent need to develop antiparasitic agents with new modes of action. Gene-encoded antimicrobial peptides (AMPs) are promising candidates. They are lethal for a broad spectrum of pathogens, but little is known about their activity and mode of action against the insect (promastigote) and the mammalian (amastigote) stage of the Leishmania parasite. We report on the lethal activity of bombinin H2 and H4, two AMPs isolated from the skin secretions of Bombina variegata, which differ one from each other by only the configuration of a single amino acid. We found that H4, which represents the first natural AMP of animal origin containing a D-amino acid in its sequence, is the most active one. The mode of action of the peptides on Leishmania and model membranes was investigated. These studies include: membrane depolarizition, membrane leakage and damage, membrane binding (using surface plasmon resonance) and the determination of the structure and organization of the peptide in Leishmania mimicking membranes (using ATR-FTIR spectroscopy). Our results highlight the importance of a single a-amino acid epimerization as a tool used by nature to modulate the activity of AMPs. In addition, our findings suggest bombinins H as potential templates for the design of new drugs with a new mode of action against Leishmania
LPS is a Key Molecule in the Synergistic Effect of Temporins on Gram-Negative Bacteria
No full textThe growing emergence of multidrug-resistant microbes requires the discovery of new antibiotics with new modes of action. Naturally occurring antimicrobial peptides (AMPs), which are produced by almost all forms of life, represent promising candidates [1].
There is compelling evidence that unlike conventional antibiotics, most AMPs interact and increase the permeability of the bacterial membrane as part of their killing mechanism. However, before reaching it, they need to cross the cell wall that, in Gram-negative bacteria, is surrounded by the lipopolysaccharide (LPS)-outer membrane, which forms a very efficient barrier against a variety of hydrophilic and hydrophobic molecules [2, 3].
In Amphibia, temporins are among the shortest (10 to 16 residues) AMPs, with up to ten isoforms within the same specimen [4]. However, the biological significance of the coexistence of so many isoforms in a single living organism is not clear. We addressed this question using temporins A, B and L isolated from Rana temporaria skin secretion.
In this study, we show that temporins A and B, which are only weakly active on Gram-negative bacteria, can synergize, when combined each with temporin L, to overcome the bacterial resistance imposed by the LPS protective layer. Furthermore, this effect is highly dependent on the type of LPS. To understand the underlying mechanism, we investigated the effect of two types of LPS (from E. coli O111:B4 and O26:B6) on the organization of temporins, alone and when mixed one with each other. Our data indicate that the synergism between temporins is related to the ability of temporin L to prevent the oligomerization of A and B when in contact with LPS O111:B4, thus allowing their traslocation across the bacterial cell wall into the target cytoplasmic membrane [5].
Overall, such studies should contribute to the development of new peptide-based anti-infective therapeutic strategies, urgently needed because of the increasing microbial resistance to the available antibiotics.
References
1. Zasloff, M. 2002. Antimicrobial peptides of multicellular organisms. Nature. 415: 389-395.
2. Nikaido, H. 1994. Prevention of drug access to bacterial targets: permeability barriers and active efflux. Science. 264: 382-8.
3. Papo, N. and Y. Shai. 2005.A molecular mechanism for lipopolysaccharide protection of Gram-negative bacteria from antimicrobial peptides. J Biol Chem. 280: 10378-87.
4. Mangoni, M.L. 2006.Temporins, anti-infective peptides with expanding properties. Cell Mol Life Sci.
5. Rosenfeld, Y., D. Barra, M. Simmaco, Y. Shai and M.L. Mangoni. 2006. A synergism between temporins toward Gram-negative bacteria overcomes resistance imposed by the lipopolysaccharide protective layer. J Biol Chem. 281: 28565-74
A Synergistic Effect Between Temporins Control Bacterial Resistance Due to the Lipopolysaccharide Layer
No full textAntimicrobial Peptides of the Temporin Family: Features, Biological Activities and Membrane-Interactions
No full textThe increasing emergence of multidrug-resistant microbes does urgently require the discovery of new antibiotics with a new mode of action, and naturally occurring antimicrobial peptides (AMPs), which are produced by almost all living organisms, represent promising candidates (1).
Amphibian skin represents one of the richest sources for AMPs, which are synthesized and stored within granules of holocrine-type serous glands and released upon stimulation (2,3). In particular, temporins constitute a large family and are among the smallest amphipathic α-helical peptides (10-16 residues) found in nature to date, and with the lowest number of positively charged amino acids (4). Interestingly, some of them do possess attractive and unique properties including: (i) a rapid membranolytic effect against a large spectrum of pathogens (bacteria, fungi and protozoa of Leishmania genus) and lipid vesicles of different composition (5,6); (ii) preservation of biological activity in serum and in physiological salt concentration; (iii) anti-endotoxin activity by binding to lipopolysaccharide (LPS) and by inhibition of TNF-α release from LPS-activated macrophages; (iv) synergistic effect, between them, against Gram-negative bacteria to overcome the microbial resistance imposed by the LPS protective layer. LPS is the major component of the outer membrane of Gram-negative bacteria and forms an efficient barrier against a variety of molecules, including AMPs. LPS also possesses inflammatory properties which can result in a fatal phenomenon known as septic shock (7). Therefore, the ability of a peptide to display both antimicrobial and anti-endotoxin activities makes it an attractive compound for therapeutic application. Our data have indicated that membrane permeation is the major target for the killing process of temporins and that the synergistic effect of temporins A+L and B+L in the antimicrobial activity is related to the ability of temporin L to prevent the oligomerization of A and B when in contact with LPS, thus allowing their translocation across the bacterial cell wall into the target cytoplasmic membrane. We have also demonstrated that the same temporin combinations can synergize in the LPS detoxification with a molecular mechanism which is different from that controlling the synergistic effect in the antimicrobial activity against Gram-negative bacteria (8). However, the two types of synergism are highly dependent on the type of LPS. Besides improving our knowledge on the peptide-membrane interaction, such studies should give a valuable contribution to assist in the future design and manufacturing of new peptide-based anti-infective and antisepsis drugs with a new mode of action.
1. Zasloff M, Nature 2002; 415: 389-395
2. Mangoni ML et al., FASEB J. 2001; 15: 1431-1432
3. Rinaldi AC. Curr. Opin. Chem. Biol. 2002; 6: 799-804
4. Simmaco M et al, Eur. J. Biochem. 1996; 242: 788-792
5. Mangoni ML et al, J. Biol. Chem. 2005; 280: 984-990
6. Rinaldi AC et al, Biochem. J. 2002; 368: 91-100
7. Stone R, Science 1994; 264: 365-367
8. Mangoni ML et al, J. Biol. Chem. 2008; 283: 22907-2291
Peptide-Lipid Interaction: Shedding Light into the Mode of Action and Cell Specificity of Antimicrobial Peptides
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