1.
Bysell, Helena, et al.
(författare)
Binding and release of consensus peptides by poly(acrylic acid) microgels
2009
Ingår i: Biomacromolecules. - : American Chemical Society. - 1525-7797 .- 1526-4602. ; 10:8, s. 2162-2168
Tidskriftsartikel (refereegranskat) abstract
The interaction between positively charged consensus peptides and poly(acrylic acid) microgels was investigated with micromanipulator-assisted light microscopy and confocal laser scanning microscopy. Peptide binding and release was monitored by microgel deswelling and swelling for monodisperse multiples of heparin-binding Cardin and Weintraub motifs, (AKKARA)(n) (1 <= n <= 4) and (ARKKAAKA)(n) (1 <= n <= 3), as well as the corresponding titratable (AHHAHA)(4) and (AHHHAAHA)(3) peptides (A, K. R and H, refering to alanine, lysine, arginine, and histidine, respectively). When fully charged, these peptides distribute homogenously throughout the microgels and display concentration-dependent deswelling, which increases with increasing peptide length. Both (AKKARA)(4) and (ARKKAAKA)(3) display potent and fast microgel deswelling but only marginal subsequent electrolyte-induced desorption. In contrast, reducing the peptide charge for (AHHAHA)(4) and (AHHHAAHA)(3) at neutral and high pH, or the peptide length, substantially reduces the peptide affinity for the microgels and facilitates rapid peptide release. Taken together, the results also show that quite short peptides of moderate charge density interact strongly and cause extensive gel deswelling of oppositely charged microgels, precluding peptide release. They also show, however, that desirable triggered release can be achieved with peptides of lower charge density.
2.
Kacprzyk, Lukasz, et al.
(författare)
Antimicrobial activity of histidine-rich peptides is dependent on acidic conditions
2007
Ingår i: Biochimica et Biophysica Acta - Biomembranes. - : Elsevier BV. - 0005-2736 .- 1879-2642. ; 1768:11, s. 2667-2680
Tidskriftsartikel (refereegranskat) abstract
Synthetic peptides composed of multiples of the consensus heparin-binding Cardin and Weintraub sequences AKKARA and ARKKAAKA are antimicrobial. Replacement of lysine and arginine by histidine in these peptides completely abrogates their antimicrobial and heparin-binding activities at neutral pH. However, the antibacterial activity against Gram-negative (Escherichia coli, Pseudomonas aeruginosa) and Gram-positive bacteria (Bacillus subtilis and Staphylococcus aureus) as well as the fungus Candida albicans, was restored at acidic conditions (pH 5.5). Fluorescence microscopy and FACS analysis showed that the binding of the histidine-rich peptides to E. coli and Candida was significantly enhanced at pH 5.5. Likewise, fluorescence studies for assessment of membrane permeation as well as electron microscopy analysis of peptide-treated bacteria, paired with studies of peptide effects on liposomes, demonstrated that the peptides induce membrane lysis only at acidic pH. No discernible hemolysis was noted for the histidine-rich peptides. Similar pH-dependent antimicrobial activities were demonstrated for peptides derived from histidine-rich and heparin-binding regions of human kininogen and histidine-rich glycoprotein. The results demonstrate that the presence of art acidic environment is an important regulator of the activity of histidine-rich antimicrobial peptides.
3.
4.
Malmsten, Martin, et al.
(författare)
Antimicrobial peptides derived from growth factors
2007
Ingår i: Growth Factors. - : Informa UK Limited. - 0897-7194 .- 1029-2292. ; 25:1, s. 60-70
Tidskriftsartikel (refereegranskat) abstract
Growth factors, comprising diverse protein and peptide families, are involved in a multitude of developmental processes, including embryogenesis, angiogenesis, and wound healing. Here we show that peptides derived from HB-EGF, amphiregulin, hepatocyte growth factor, PDGF-A and PDGF-B, as well as various FGFs are antimicrobial, demonstrating a previously unknown activity of growth factor-derived peptides. The peptides killed the Gram-negative bacteria Escherichia coli, Pseudomonas aeruginosa, and the Gram-positive Bacillus subtilis, as well as the fungus Candida albicans. Several peptides were also active against the Gram-positive S. aureus. Electron microscopy analysis of peptide-treated bacteria, paired with analysis of peptide effects on liposomes, showed that the peptides exerted membrane-breaking effects similar to those seen after treatment with the “classical” human antimicrobial peptide LL-37. Furthermore, HB-EGF was antibacterial per se, and its epitope GKRKKKGKGLGKKRDPCLRKYK retained its activity in presence of physiological salt and plasma. No discernible hemolysis was noted for the growth factor-derived peptides. Besides providing novel templates for design of peptide-based antimicrobials, our findings demonstrate a previously undisclosed link between the family of growth factors and antimicrobial peptides, both of which are induced during tissue remodelling and repair.
5.
Pasupuleti, Mukesh, et al.
(författare)
Antimicrobial activity of a C-terminal peptide from human extracellular superoxide dismutase
2009
Ingår i: BMC research notes. - : Springer Science and Business Media LLC. - 1756-0500. ; 2, s. 136-
Tidskriftsartikel (refereegranskat) abstract
BACKGROUND: Antimicrobial peptides (AMP) are important effectors of the innate immune system. Although there is increasing evidence that AMPs influence bacteria in a multitude of ways, bacterial wall rupture plays the pivotal role in the bactericidal action of AMPs. Structurally, AMPs share many similarities with endogenous heparin-binding peptides with respect to secondary structure, cationicity, and amphipathicity. FINDINGS: In this study, we show that RQA21 (RQAREHSERKKRRRESECKAA), a cationic and hydrophilic heparin-binding peptide corresponding to the C-terminal region of extracellular superoxide dismutase (SOD), exerts antimicrobial activity against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus subtilis and Candida albicans. The peptide was also found to induce membrane leakage of negatively charged liposomes. However, its antibacterial effects were abrogated in physiological salt conditions as well as in plasma. CONCLUSION: The results provide further evidence that heparin-binding peptide regions are multifunctional, but also illustrate that cationicity alone is not sufficient for AMP function at physiological conditions. However, our observation, apart from providing a link between heparin-binding peptides and AMPs, raises the hypothesis that proteolytically generated C-terminal SOD-derived peptides could interact with, and possibly counteract bacteria. Further studies are therefore merited to study a possible role of SOD in host defence.
6.
Pasupuleti, Mukesh, et al.
(författare)
Antimicrobial activity of human prion protein is mediated by its N-terminal region
2009
Ingår i: PloS one. - : Public Library of Science (PLoS). - 1932-6203. ; 4:10, s. e7358-
Tidskriftsartikel (refereegranskat) abstract
BACKGROUND: Cellular prion-related protein (PrP(c)) is a cell-surface protein that is ubiquitously expressed in the human body. The multifunctionality of PrP(c), and presence of an exposed cationic and heparin-binding N-terminus, a feature characterizing many antimicrobial peptides, made us hypothesize that PrP(c) could exert antimicrobial activity. METHODOLOGY AND PRINCIPAL FINDINGS: Intact recombinant PrP exerted antibacterial and antifungal effects at normal and low pH. Studies employing recombinant PrP and N- and C-terminally truncated variants, as well as overlapping peptide 20mers, demonstrated that the antimicrobial activity is mediated by the unstructured N-terminal part of the protein. Synthetic peptides of the N-terminus of PrP killed the Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa, and the Gram-positive Bacillus subtilis and Staphylococcus aureus, as well as the fungus Candida parapsilosis. Fluorescence studies of peptide-treated bacteria, paired with analysis of peptide effects on liposomes, showed that the peptides exerted membrane-breaking effects similar to those seen after treatment with the "classical" human antimicrobial peptide LL-37. In contrast to LL-37, however, no marked helix induction was detected for the PrP-derived peptides in presence of negatively charged (bacteria-mimicking) liposomes. PrP furthermore showed an inducible expression during wounding of human skin ex vivo and in vivo, as well as stimulation of keratinocytes with TGF-alpha in vitro. CONCLUSIONS: The demonstration of an antimicrobial activity of PrP, localisation of its activity to the N-terminal and heparin-binding region, combined with results showing an increased expression of PrP during wounding, indicate that PrPs could have a previously undisclosed role in host defense.
7.
Pasupuleti, Mukesh, et al.
(författare)
End-tagging of ultra-short antimicrobial peptides by W/F stretches to facilitate bacterial killing
2009
Ingår i: PloS one. - : Public Library of Science (PLoS). - 1932-6203. ; 4:4, s. e5285-
Tidskriftsartikel (refereegranskat) abstract
BACKGROUND: Due to increasing resistance development among bacteria, antimicrobial peptides (AMPs), are receiving increased attention. Ideally, AMP should display high bactericidal potency, but low toxicity against (human) eukaryotic cells. Additionally, short and proteolytically stable AMPs are desired to maximize bioavailability and therapeutic versatility. METHODOLOGY AND PRINCIPAL FINDINGS: A facile approach is demonstrated for reaching high potency of ultra-short antimicrobal peptides through end-tagging with W and F stretches. Focusing on a peptide derived from kininogen, KNKGKKNGKH (KNK10) and truncations thereof, end-tagging resulted in enhanced bactericidal effect against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus. Through end-tagging, potency and salt resistance could be maintained down to 4-7 amino acids in the hydrophilic template peptide. Although tagging resulted in increased eukaryotic cell permeabilization at low ionic strength, the latter was insignificant at physiological ionic strength and in the presence of serum. Quantitatively, the most potent peptides investigated displayed bactericidal effects comparable to, or in excess of, that of the benchmark antimicrobial peptide LL-37. The higher bactericidal potency of the tagged peptides correlated to a higher degree of binding to bacteria, and resulting bacterial wall rupture. Analogously, tagging enhanced peptide-induced rupture of liposomes, particularly anionic ones. Additionally, end-tagging facilitated binding to bacterial lipopolysaccharide, both effects probably contributing to the selectivity displayed by these peptides between bacteria and eukaryotic cells. Importantly, W-tagging resulted in peptides with maintained stability against proteolytic degradation by human leukocyte elastase, as well as staphylococcal aureolysin and V8 proteinase. The biological relevance of these findings was demonstrated ex vivo for pig skin infected by S. aureus and E. coli. CONCLUSIONS/SIGNIFICANCE: End-tagging by hydrophobic amino acid stretches may be employed to enhance bactericidal potency also of ultra-short AMPs at maintained limited toxicity. The approach is of general applicability, and facilitates straightforward synthesis of hydrophobically modified AMPs without the need for post-peptide synthesis modifications.
8.
Pasupuleti, Mukesh, et al.
(författare)
Preservation of Antimicrobial Properties of Complement Peptide C3a, from Invertebrates to Humans
2007
Ingår i: Journal of Biological Chemistry. - 0021-9258 .- 1083-351X. ; 282:4, s. 2520-2528
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.
9.
Reijmar, K., et al.
(författare)
Bactericidal and hemolytic properties of mixed LL-37/surfactant systems
2007
Ingår i: Journal of drug delivery science and technology. - 1773-2247. ; 17:4, s. 293-297
Tidskriftsartikel (refereegranskat) abstract
The interaction between acyl chain homologues (C10 and C12) of n-acyl β-D-maltoside and the antimicrobial peptide LL-37 (LLGDFFRKSKEKIGKEFKRIVQRIKDFLRNLVPRTES) was investigated. Emphasis was placed on peptide-micelle complexation and its consequences for peptide proteolytic stability, as well as bactericidal and hemolytic effects of the mixed systems. From circular dichroism and liposome leakage experiments, it was found that LL-37 interacts with both surfactants investigated, and that this reduces the effective free peptide concentration. Analogously, LL-37 displayed increased proteolytic stability towards Pseudomonas aeruginosa elastase in surfactant solution. Despite this, conditions can be found at which the bactericidal effect of mixed peptide-surfactant systems is comparable to that of free LL-37. However, also a number of challenges to this type of antimicrobial peptide (AMP) carrier system were identified, notably related to reduction of bactericidal effect for some systems, and occurrence of hemolysis for mixed peptide-surfactant systems displaying advantageous bactericidal effects. Any use of such AMP carrier systems will therefore have to be carefully optimized in order to retain bactericidal activity and minimize toxicity.
10.
Ringstad, Lovisa, et al.
(författare)
An electrochemical study into the interaction between complement-derived peptides and DOPC mono- and bilayers.
2008
Ingår i: Langmuir. - : American Chemical Society (ACS). - 0743-7463 .- 1520-5827. ; 24:1, s. 208-216
Tidskriftsartikel (refereegranskat) abstract
Electrochemical methods employing the hanging mercury drop electrode were used to study the interaction between variants of the complement-derived antimicrobial peptide CNY21 (CNYITELRRQH ARASHLGLAR) and dioleoyl phosphatidylcholine (DOPC) monolayers. Capacitance potential and impedance measurements showed that the CNY21 analogues investigated interact with DOPC monolayers coating the mercury drop. Increasing the peptide hydrophobicity by substituting the two histidine residues with leucine resulted in a deeper peptide penetration into the hydrophobic region of the DOPC monolayer, indicated by an increase in the dielectric constant of the lipid monolayer (Deltaepsilon = 2.0 after 15 min interaction). Increasing the peptide net charge from +3 to +5 by replacing the histidines by lysines, on the other hand, arrests the peptide in the lipid head group region. Reduction of electroactive ions (Tl+, Pb2+, Cd2+, and Eu3+) at the monolayer-coated electrode was employed to further characterize the types of defects induced by the peptides. All peptides studied permeabilize the monolayer to Tl+ to an appreciable extent, but this effect is more pronounced for the more hydrophobic peptide (CNY21L), which also allows penetration of larger ions and ions of higher valency. The results for the various ions indicate that charge repulsion rather than ion size is the determining factor for cation penetration through peptide-induced defects in the DOPC monolayer. The effects obtained for monolayers were compared to results obtained with bilayers from liposome leakage and circular dichroism studies for unilamellar DOPC vesicles, and in situ ellipsometry for supported DOPC bilayers. Trends in peptide-induced liposome leakage were similar to peptide effects on electrochemical impedance and permeability of electroactive ions for the monolayer system, demonstrating that formation of transmembrane pores alone does not constitute the mechanism of action for the peptides investigated. Instead, our results point to the importance of local packing defects in the lipid membrane in close proximity to the adsorbed peptide molecules.
