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- Nordahl, Emma, et al.
(författare)
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Domain 5 of high molecular weight kininogen is antibacterial.
- 2005
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Ingår i: Journal of Biological Chemistry. - 1083-351X. ; 280:41, s. 34832-34839
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Tidskriftsartikel (refereegranskat)abstract
- Antimicrobial peptides are important effectors of the innate immune system. These peptides belong to a multifunctional group of molecules that apart from their antibacterial activities also interact with mammalian cells and glycosaminoglycans and control chemotaxis, apoptosis, and angiogenesis. Here we demonstrate a novel antimicrobial activity of the heparin-binding and cell-binding domain 5 of high molecular weight kininogen. Antimicrobial epitopes of domain 5 were characterized by analysis of overlapping peptides. A peptide, HKH20 (His(479) - His(498)), efficiently killed the Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa and the Gram-positive Enterococcus faecalis. Fluorescence microscopy and electron microscopy demonstrated that HKH20 binds to and induces breaks in bacterial membranes. Furthermore, no discernible hemolysis or membrane-permeabilizing effects on eukaryotic cells were noted. Proteolytic degradation of high molecular weight kininogen by neutrophil-derived proteases as well as the metalloproteinase elastase from P. aeruginosa yielded fragments comprising HKH20 epitopes, indicating that kininogen-derived antibacterial peptides are released during proteolysis.
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- Nordahl, Emma
(författare)
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Novel Endogenous Antimicrobial Peptides
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Antimicrobial peptides serve as a first line of defence against invading microorganisms and are an essential part of our fast innate immune system. They are ancient molecules found in all classes of life. Antimicrobial peptides rapidly kill a broad spectrum of microbes and are immunomodulatory, i.e. having additional actions influencing inflammation and other innate immune responses. Results presented in this thesis demonstrate that proteases of common human pathogens degrade and inactivate the antimicrobial peptide LL-37, probably a strategy for bacteria to circumvent the action of antimicrobial peptides. Likewise, heavily sulphated glycosaminoglycans like dermatan sulphate and heparin were shown to bind to and inactivate LL-37. Furthermore, we demonstrate that structural characteristics associated with heparin affinity (cationicity and amphipathicity) may confer antimicrobial properties to any given peptide. Heparin-binding consensus sequences were proven to be active against Gram-positive bacteria, Gram-negative bacteria and the fungus Candida albicans. Similar results were obtained with synthetic peptides derived from heparin-binding sequences within endogenous proteins. In addition, novel antimicrobial activity and heparin-binding capacity were discovered for the anaphylatoxin C3a, generated during activation of the complement system, and the inactive derivative of C3a (C3adesArg), as well as shorter synthetic peptides from the molecule. Novel antimicrobial activity was also shown for the heparin binding and cell-binding domain 5 of high molecular weight kininogen, a substrate in the intrinsic pathway of coagulation. Interestingly, the peptide HKH20 (His479 His498) from this domain was active in high salt, and highly resistant to degradation by various bacterial proteases. The understanding that heparin binding is a property of many antimicrobial peptides may represent a powerful tool in the discovery of novel endogenous antimicrobial peptides from complex biological mixtures.
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- Pasupuleti, Mukesh, et al.
(författare)
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Preservation of Antimicrobial Properties of Complement Peptide C3a, from Invertebrates to Humans
- 2007
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Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 282:4, s. 2520-2528
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Tidskriftsartikel (refereegranskat)abstract
- The human anaphylatoxin peptide C3a, generated during complement activation, exerts antimicrobial effects. Phylogenetic analysis, sequence analyses, and structural modeling studies paired with antimicrobial assays of peptides from known C3a sequences showed that, in particular in vertebrate C3a, crucial structural determinants governing antimicrobial activity have been conserved during the evolution of C3a. Thus, regions of the ancient C3a from Carcinoscorpius rotundicauda as well as corresponding parts of human C3a exhibited helical structures upon binding to bacterial lipopolysaccharide permeabilized liposomes and were antimicrobial against Gram-negative and Gram-positive bacteria. Human C3a and C4a (but not C5a) were antimicrobial, in concert with the separate evolutionary development of the chemotactic C5a. Thus, the results demonstrate that, notwithstanding a significant sequence variation, functional and structural constraints imposed on C3a during evolution have preserved critical properties governing antimicrobial activity.
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- Ringstad, Lovisa, et al.
(författare)
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Composition Effect on Peptide Interaction with Lipids and Bacteria : Variants of C3a Peptide CNY21
- 2007
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Ingår i: Biophysical Journal. - : Elsevier BV. - 0006-3495 .- 1542-0086. ; 92:1, s. 87-98
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Tidskriftsartikel (refereegranskat)abstract
- The effect of peptide hydrophobicity and charge on peptide interaction with model lipid bilayers was investigated for the C3a-derived peptide CNY21 by fluorescence spectroscopy, circular dichroism, ellipsometry, z-potential, and photon correlation spectroscopy measurements. For both zwitterionic and anionic liposomes, the membrane-disruptive potency for CNY21 variants increased with increasing net positive charge and mean hydrophobicity and was completely lost on elimination of all peptide positive charges. Analogous effects of elimination of the peptide positive net charge in particular were found regarding bacteria killing for both Pseudomonas aeruginosa and Bacillus subtilis. The peptides, characterized by moderate helix content both in buffer and when attached to the liposomes, displayed high adsorption for the net positively charged peptide variants, whereas adsorption was nonmeasurable for the uncharged peptide. That electrostatically driven adsorption represents the main driving force for membrane disruption in lipid systems was also demonstrated by a drastic reduction in both liposome leakage and peptide adsorption with increasing ionic strength, and this salt inactivation can be partly avoided by increasing the peptide hydrophobicity. This increased electrolyte resistance translates also to a higher antibacterial effect for the hydrophobically modified variant at high salt concentration. Overall, our findings demonstrate the importance of the peptide adsorption and resulting peptide interfacial density for membrane-disruptive effects of these peptides.
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- Sonesson, Andreas, et al.
(författare)
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Antifungal activities of peptides derived from domain 5 of high-molecular-weight kininogen.
- 2011
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Ingår i: International Journal of Peptides. - : Hindawi Limited. - 1687-9775 .- 1687-9767. ; 2011:Sep 14
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Tidskriftsartikel (refereegranskat)abstract
- In both immunocompromised and immunocompetent patients, Candida and Malassezia are causing or triggering clinical manifestations such as cutaneous infections and atopic eczema. The innate immune system provides rapid responses to microbial invaders, without requiring prior stimulation, through a sophisticated system of antimicrobial peptides (AMPs). High molecular weight kininogen (HMWK) and components of the contact system have previously been reported to bind to Candida and other pathogens, leading to activation of the contact system. A cutaneous Candida infection is characterized by an accumulation of neutrophils, leading to an inflammatory response and release of enzymatically active substances. In the present study we demonstrate that antifungal peptide fragments are generated through proteolytic degradation of HMWK. The recombinant domain 5 (rD5) of HMWK, D5-derived peptides, as well as hydrophobically modified D5-derived peptides efficiently killed Candida and Malassezia. Furthermore, the antifungal activity of modified peptides was studied at physiological conditions. Binding of a D5-derived peptide, HKH20 (His(479)-His(498)), to the fungal cell membrane was visualized by fluorescence microscopy. Our data disclose a novel antifungal activity of D5-derived peptides and also show that proteolytic cleavage of HMWK results in fragments exerting antifungal activity. Of therapeutic interest is that structurally modified peptides show an enhanced antifungal activity.
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- Sonesson, Andreas, et al.
(författare)
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Antifungal activity of C3a and C3a-derived peptides against Candida
- 2007
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Ingår i: Biochimica et Biophysica Acta - Biomembranes. - : Elsevier BV. - 0005-2736 .- 1879-2642. ; 1768:2, s. 346-353
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Tidskriftsartikel (refereegranskat)abstract
- Antimicrobial peptides are generated during activation of the complement system [Nordahl et al. Proc. Natl. Acad. Sci. U. S. A. 2004, 101:16879-16884]. Here we show that the anaphylatoxin C3a exerts antimicrobial effects against the yeast Candida. Fluorescence microscopy and electron microscopy analysis demonstrated that C3a-derived peptides bound to the cell surface of Candida, and induced membrane perturbations and release of extracellular material. Various Candida isolates were found to induce complement degradation, leading to generation of C3a. Arginine residues were found to be critical for the antifungal and membrane breaking activity of a C3a-derived antimicrobial peptide, CNY21 (C3a; Cys57–Arg77). A CNY21 variant with increased positive net charge displayed enhanced antifungal activity. Thus, C3a-derived peptides can be utilized as templates in the development of peptide-based antifungal therapies.
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