Sunday, January 22, 2012

antimicrobial peptide | What isantimicrobial peptide |Papers on antimicrobial peptide|Research on antimicrobial peptide | Publications on antimicrobi


1.
J Biol Chem. 2012 Jan 18. [Epub ahead of print]

Structure-activity analysis of the dermcidin-derived peptide DCD 1L, an anionicantimicrobial peptide present in human sweat.

Source

University of Tuebingen, Germany;

Abstract

Dermcidin encodes the anionic amphiphilic peptide DCD 1L, which displays a broad spectrum of antimicrobial activity under conditions resembling those in human sweat. Here, we have investigated its mode of antimicrobial activity. We found that DCD 1L interacts preferentially with negatively charged bacterial phospholipids with a helix axis which is aligned flat on a lipid bilayer surface. Upon interaction with lipid bilayers DCD 1L forms oligomeric complexes which are stabilized by Zn2+. DCD-1L is able to form ion channels in the bacterial membrane and we propose that Zn2+-induced self-assembly of DCD 1L upon interaction with bacterial lipid bilayers is a prerequisite for ion channel formation. These data allow for the first time to propose a molecular model for the antimicrobial mechanism of a naturally processed human anionic peptide that is active under the harsh conditions present in human sweat.

PMID:
22262861
[PubMed - as supplied by publisher]
2.
Wiley Interdiscip Rev RNA. 2012 Jan 19. doi: 10.1002/wrna.1108. [Epub ahead of print]

Roles of tRNA in cell wall biosynthesis.

Source

Department of Microbiology, Ohio State University, Columbus, OH, USA.

Abstract

Recent research into various aspects of bacterial metabolism such as cell wall and antibiotic synthesis, degradation pathways, cellular stress, and amino acid biosynthesis has elucidated roles of aminoacyl-transfer ribonucleic acid (aa-tRNA) outside of translation. Although the two enzyme families responsible for cell wall modifications, aminoacyl-phosphatidylglycerol synthases (aaPGSs) and Fem, were discovered some time ago, they have recently become of intense interest for their roles in the antimicrobial resistance of pathogenic microorganisms. The addition of positively charged amino acids to phosphatidylglycerol (PG) by aaPGSs neutralizes the lipid bilayer making the bacteria less susceptible to positively charged antimicrobial agents. Fem transferases utilize aa-tRNA to form peptide bridges that link strands of peptidoglycan. These bridges vary among the bacterial species in which they are present and play a role in resistance to antibiotics that target the cell wall. Additionally, the formation of truncated peptides results in shorterpeptide bridges and loss of branched linkages which makes bacteria more susceptible to antimicrobials. A greater understanding of the structure and substrate specificity of this diverse enzymatic family is necessary to aid current efforts in designing potential bactericidal agents. These two enzyme families are linked only by the substrate with which they modify the cell wall, aa-tRNA; their structure, cell wall modification processes and the physiological changes they impart on the bacterium differ greatly. WIREs RNA 2012. doi: 10.1002/wrna.1108 For further resources related to this article, please visit the WIREs website.

Copyright © 2012 John Wiley & Sons, Ltd.

PMID:
22262511
[PubMed - as supplied by publisher]
3.
J Innate Immun. 2012 Jan 19. [Epub ahead of print]

Activity, Expression and Genetic Variation of Canine β-Defensin 103: A Multifunctional Antimicrobial Peptide in the Skin of Domestic Dogs.

Source

Department of Microbiology and Immunology, UC Davis School of Medicine, Davis, Calif., USA.

Abstract

The skin functions as more than a physical barrier to infection. Epithelial cells of the skin can synthesize antimicrobialpeptides, including defensins, which exhibit direct antimicrobial activity. Here we characterize the expression pattern, genetic variation and activity of the major β-defensin expressed in canine skin, canine β-defensin 103 (CBD103). The gene encoding CBD103 exhibits two forms of polymorphism: a common 3-basepair deletion allele and a gene copy-number variation. Golden retrievers and Labrador retrievers were the only breeds that encoded the variant allele of CBD103, termed CBD103ΔG23. Both these breeds also exhibited a CBD103 gene copy-number polymorphism that ranged from 2 to 4 gene-copies per diploid genome. Recombinant CBD103 and CBD103ΔG23, as well as the human ortholog human β-defensin 3 (hBD3) and hBD3ΔG23, showed potent and comparable antimicrobial killing against both methicillin-susceptible and methicillin-resistant Staphylococcus pseudintermedius. Skin biopsy specimens from dogs with atopic dermatitis revealed CBD103 expression levels similar to those in healthy controls and comparable at lesional and nonlesional sites. This expression pattern in dogs differs from the previously reported reduced expression of the human ortholog in atopic dermatitis. Overall, the similarities of CBD103 and its human ortholog reported here support the notion that the domestic dog may serve as a valuable model for studying β-defensin biology in the skin.

Copyright © 2012 S. Karger AG, Basel.

PMID:
22261569
[PubMed - as supplied by publisher]
4.
J Innate Immun. 2012 Jan 10. [Epub ahead of print]

The Antimicrobial Peptide hLF1-11 Drives Monocyte-Dendritic Cell Differentiation toward Dendritic Cells That Promote Antifungal Responses and Enhance Th17 Polarization.

Source

Department of Infectious Diseases, Leiden University Medical Center, Leiden, The Netherlands.

Abstract

The hLF1-11 peptide comprising the first 11 N-terminal residues of human lactoferrin exerts antimicrobial activity in vivo, enhances the inflammatory response of monocytes and directs monocyte-macrophage differentiation toward cells with enhanced antimicrobial properties. In this study, we investigated the effects of hLF1-11 on human monocyte-dendritic cell (DC) differentiation and subsequent T cell activation. Results revealed that - compared to control (peptide-incubated) DCs - hLF1-11-differentiated DCs displayed enhanced expression of HLA class II antigens and dectin-1, and increased phagocytosis of Candida albicans. In addition, hLF1-11-differentiated DCs produced enhanced amounts of reactive oxygen species, IL-6 and IL-10, but not IL-12p40 and TNF-α, upon stimulation with C. albicans. Moreover, 6-day-cultured hLF1-11-differentiated DCs and control (peptide-incubated) DCs that had been stimulated with a Th17-inducing mix of antigens (including C. albicans) for 24 h were cocultured with autologous CD4+ T cells for 72 h and then the levels of IL-10, IL-17 and IFN-γ production and the percentage of cytokine-producing T cells were assessed. The results revealed that the hLF1-11-differentiated DCs induced an enhanced IL-17, but reduced IFN-γ, production by T cells as compared to control (peptide-incubated) DCs. Collectively, the hLF1-11 peptide drives monocyte-DC differentiation toward DCs that promote antifungal responses and enhance Th17 polarization.

Copyright © 2012 S. Karger AG, Basel.

PMID:
22261275
[PubMed - as supplied by publisher]
5.
ACS Chem Biol. 2012 Jan 19. [Epub ahead of print]

The importance of the cell membrane on the mechanism of action of cyclotides.

Abstract

Their distinctive structures, diverse range of bioactivities, and potential for pharmaceutical or agricultural applications make cyclotides an intriguing family of cyclic peptides. Together with the physiological role in plant host defence, cyclotides possess antimicrobial, anticancer and anti-HIV activities. In all of the reported activities, cell membranes seem to be the primary target for cyclotide binding. This article examines recent literature on cyclotide-membrane studies and highlights the hypothesis that the activity of cyclotides is dependent on their affinity for lipid bilayers and enhanced by the presence of specific lipids, i.e., phospholipids containing phosphatidylethanolamine headgroups. There is growing evidence that the lipid composition of target cell membranes dictates the amount of cyclotides bound to the cell and the extent of their activity. After membrane targeting and insertion in the bilayer core, cyclotides induce disruption of membranes by a pore formation mechanism. This proposed mechanism of action is supported by biophysical studies with model membranes and by studies on natural biological membranes of known lipid compositions.

PMID:
22260456
[PubMed - as supplied by publisher]
6.
Nat Prod Res. 2012 Jan 19. [Epub ahead of print]

Extraction of the antimicrobial peptide cerein 8A by aqueous two-phase systems and aqueous two-phase micellar systems.

Source

a Laboratório de Bioquímica e Microbiologia Aplicada, Departamento de Ciência de Alimentos , Universidade Federal do Rio Grande do Sul , 91501-970 Porto Alegre , Brazil.

Abstract

Cerein 8A is an antimicrobial peptide with potential application against food spoilage and pathogenic bacteria. The partitioning of cerein 8A was investigated in two liquid-liquid extraction systems that are considered promising for bioseparation and purification purposes. Aqueous two-phase systems (ATPSs) were prepared with polyethylene glycol (PEG) and inorganic salts, and the addition of NaCl was investigated in this system. The best results concerning partition coefficients (K (b)) were obtained with PEG + ammonium sulphate, and K (b) value significantly increases when NaCl was added. Cerein 8A was effectively extracted into the micelle-rich phase in a 4% Triton X-114 medium. Recovery yield was higher for ATPS compared to micellar systems. Cerein 8A can be isolated from a crude suspension containing the bioactive molecule by ATPSs. Successful implementation of peptide partitioning represents an important step towards developing a low-cost effective separation method for cerein 8A.

PMID:
22260198
[PubMed - as supplied by publisher]
7.
Sheng Wu Gong Cheng Xue Bao. 2011 Oct;27(10):1408-16.

[Research progress in fusion expression of antimicrobial peptides].

[Article in Chinese]

Source

Laboratory of Feed Biotechnology, State Key Laboratory of Animal Nutrition, China Agricultural University, Beijing 100193, China.

Abstract

Antimicrobial peptides (AMPs) are of great significance in the field of food, feed and medicine due to their wide spectrum of antimicrobial activity and new mechanism of action different from conventional antibiotics. AMPs production from natural sources is usually limited, and chemical synthesis is not economically practical, especially for the production of long peptides. Therefore, heterologous expression of AMPs has been widely studied as an alternative, and fusion expression plays an important role in increasing production. The present review mainly focuses on the types and bioactivities of AMPs. In addition, the recent strategies to the most commonly used carrier proteins for fusion expression of AMPs and prospects for future research were also discussed.

PMID:
22260057
[PubMed - in process]
8.
Dermatoendocrinol. 2011 Oct;3(4):220-9. Epub 2011 Oct 1.

Antimicrobial implications of vitamin D.

Source

Mountain Home VAMC Medicine Service; Mountain Home; TN USA.

Abstract

Evidence exists that vitamin D has a potential antimicrobial activity and its deficiency has deleterious effects on general well-being and longevity. Vitamin D may reduce the risk of infection through multiple mechanisms. Vitamin D boosts innate immunity by modulating production of anti-microbial peptides (AMPs) and cytokine response. Vitamin D and its analogues via these mechanisms are playing an increasing role in the management of atopic dermatitis, psoriasis, vitiligo, acne and rosacea. Vitamin D may reduce susceptibility to infection in patients with atopic dermatitis and the ability to regulate local immune and inflammatory responses offers exciting potential for understanding and treating chronic inflammatory dermatitides. Moreover, B and T cell activation as well as boosting the activity of monocytes and macrophages also contribute to a potent systemic anti-microbial effect. The direct invasion by pathogenic organisms may be minimized at sites such as the respiratory tract by enhancing clearance of invading organisms. A vitamin D replete state appears to benefit most infections, with the possible noteworthy exception of Leishmaniasis. Antibiotics remain an expensive option and misuse of these agents results in significant antibiotic resistance and contributes to escalating health care costs. Vitamin D constitutes an inexpensive prophylactic option and possibly therapeutic product either by itself or as a synergistic agent to traditional antimicrobial agents. This review outlines the specific antimicrobialproperties of vitamin D in combating a wide range of organisms. We discuss the possible mechanisms by which vitamin D may have a therapeutic role in managing a variety of infections.

PMID:
22259647
[PubMed - in process]
9.
Arch Virol. 2012 Jan 19. [Epub ahead of print]

Infection of honey bees with acute bee paralysis virus does not trigger humoral or cellular immune responses.

Source

BEEgroup, Biocentre, University of Würzburg, Am Hubland, 97074, Würzburg, Germany.

Abstract

We have studied the responses of honey bees at different life stages (Apis mellifera) to controlled infection with acute bee paralysis virus and have identified the haemolymph of infected larvae and adult worker bees as the compartment where massive propagation of ABPV occurs. Insects respond with a broad spectrum of induced innate immune reactions to bacterial infections, whereas defence mechanisms based on RNA interference play a major role in antiviral immunity. In this study, we have determined that honey bee larvae and adult workers do not produce a humoral immune reaction upon artificial infection with ABPV, in contrast to control individuals challenged with Escherichia coli. ABPV-infected bees produced neither elevated levels of specific antimicrobial peptides (AMPs), such as hymenoptaecin and defensin, nor any general antimicrobial activity, as revealed by inhibition-zone assays. Additionally, adult bees did not generate melanised nodules upon ABPV infection, an important cellular immune function activated by bacteria and viruses in some insects. Challenge of bees with both ABPV and E. coli showed that innate humoral and cellular immune reactions are induced in mixed infections, albeit at a reduced level.

PMID:
22258854
[PubMed - as supplied by publisher]
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10.
Appl Microbiol Biotechnol. 2012 Jan 19. [Epub ahead of print]

Production, purification, and characterization of the cecropin from Plutella xylostella, pxCECA1, using an intein-induced self-cleavable system in Escherichia coli.

Source

State Key Laboratory of Virology, College of Life Science, Wuhan University, Wuhan, 430072, People's Republic of China.

Abstract

Antimicrobial peptides (AMPs) are widely expressed and play an important role in innate immune defense against infectious agents such as bacteria, viruses, fungi, and parasites. Cecropins are a family of AMPs synthesized in the fat body of insects that have proven effective at killing specific pathogens. In order to fulfill their clinical potential asantimicrobial drugs, a simple, cost-effective method to express AMPs is sorely needed. In this study, we expressed and characterized the cecropin from Plutella xylostella (pxCECA1) using an intein-dependent expression system in Escherichia coli. We cloned the pxCECA1 gene from larva by RT-PCR and fused the encoding sequence of mature pxCECA1 with an intein gene and a chitin-binding domain gene (CBD) in pTWIN1 plasmid. The fusion protein CBD-intein-pxCECA1 was expressed in E. coli BL21 (DE3) and separated by flowing cell extracts through a chitin column. Subsequently, self-cleavage of the intein at its C-terminus was induced in a temperature- and pH-dependent manner, resulting in the release of mature pxCECA1. The optimal conditions for self-cleavage were determined to be pH 6.0 for 48 h at 4°C, under which 12.3 mg of recombinant pxCECA1 could be recovered from 1 l of E. coli culture. The purified pxCECA1 displayed antimicrobial activity against a broad variety of gram-positive and gram-negative bacteria. This preparation was especially effective against Staphylococcus aureus, including methicillin-resistant strains. Catalase release assays demonstrated that pxCECA1 acts as a microbicidal agent. These results show for the first time that the IMPACT-TWIN expression system is an efficient, cost-effective way to produce fully functional AMPs and that the AMP pxCECA1 is a novel microbicidal agent with promising therapeutic applications.

PMID:
22258643
[PubMed - as supplied by publisher]
Click here to read
11.

Interdigitated electrodes based on impedance biosensor for sensing peptideLL-37.

Abstract

An antimicrobial peptide, LL-37, is found in an innate defense system of humans. Patients who suffer urinary tract infection (UTI) will generate LL-37 and which is released into urine. LL-37 can be used as an indicator for the diagnosis of UTI. We have designed a biosensor with an interdigitated electrode on a printed-circuit board (PCB). The surface of the electrode was modified with 3-mercaptopropionic acid and immobilized with anti-LL37 antibody to improve the specificity of the biosensor. By de-embedding jig impedance, the impedance associated with the change of LL-37 concentration was calculated. The sensitivity of this biosensor for LL-37 in a urine sample can reach 50 μg/mL.

PMID:
22254253
[PubMed - in process]
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12.
PLoS Pathog. 2012 Jan;8(1):e1002445. Epub 2012 Jan 12.

The circadian clock protein timeless regulates phagocytosis of bacteria in Drosophila.

Source

Department of Neurobiology and Behavior, Columbia University Medical School, New York, New York, United States of America.

Abstract

Survival of bacterial infection is the result of complex host-pathogen interactions. An often-overlooked aspect of these interactions is the circadian state of the host. Previously, we demonstrated that Drosophila mutants lacking the circadian regulatory proteins Timeless (Tim) and Period (Per) are sensitive to infection by S. pneumoniae. Sensitivity to infection can be mediated either by changes in resistance (control of microbial load) or tolerance (endurance of the pathogenic effects of infection). Here we show that Tim regulates resistance against both S. pneumoniae and S. marcescens. We set out to characterize and identify the underlying mechanism of resistance that is circadian-regulated. Using S. pneumoniae, we found that resistance oscillates daily in adult wild-type flies and that these oscillations are absent in Tim mutants. Drosophila have at least three main resistance mechanisms to kill high levels of bacteria in their hemolymph: melanization, antimicrobial peptides, and phagocytosis. We found that melanization is not circadian-regulated. We further found that basal levels of AMP gene expression exhibit time-of-day oscillations but that these are Tim-independent; moreover, infection-induced AMP gene expression is not circadian-regulated. We then show that phagocytosis is circadian-regulated. Wild-type flies exhibit up-regulated phagocytic activity at night; Tim mutants have normal phagocytic activity during the day but lack this night-time peak. Tim appears to regulate an upstream event in phagocytosis, such as bacterial recognition or activation of phagocytic hemocytes. Interestingly, inhibition of phagocytosis in wild type flies results in survival kinetics similar to Tim mutants after infection with S. pneumoniae. Taken together, these results suggest that loss of circadian oscillation of a specific immune function (phagocytosis) can have significant effects on long-term survival of infection.

PMID:
22253593
[PubMed - in process]
PMCID: PMC3257305
Free PMC Article
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13.
J Biol Chem. 2012 Jan 17. [Epub ahead of print]

Roles of Hydrophobicity and Charge Distribution of Cationic AntimicrobialPeptides in Peptide-Membrane Interactions.

Source

Hospital for Sick Children, Toronto, Canada;

Abstract

Cationic antimicrobial peptides (CAPs) occur as important innate immunity agents in many organisms (including humans) and offer a viable alternative to conventional antibiotics as they physically disrupt the bacterial membranes, leading to membrane lysis and eventually cell death. In the present work, we studied the biophysical and microbiological characteristics of designed CAPs varying in hydrophobicity levels and charge distributions by a variety of biophysical and biochemical approaches, including in tandem atomic force microscopy (AFM) and attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), circular dichroism spectroscopy, and SDS-PAGE. Peptide structural properties were correlated with their membrane disruptive powers and antimicrobial activities. In bacterial lipid model membranes, a time-dependent increase of aggregated beta-strand-type structure in CAPs with relatively high hydrophobicity (such as KKKKKK-ALFALWLAFLA-NH2) was essentially absent in CAPs with lower hydrophobicity (such as KKKKKK-AAFAAWAAFAA-NH2). Re-distribution of positive charges by placing three Lys residues at both termini while maintaining identical sequences minimized self-aggregation above the dimer level. Peptides containing four Leu residues were destructive to mammalian model membranes, while those with corresponding Ala residues were not. This finding was mirrored in hemolysis studies in human erythrocytes, where Ala-only peptides displayed virtually no hemolysis up to 320 μM, but the four-Leu peptides induced 40-80% hemolysis in the same concentration range. Allpeptides studied displayed strong antimicrobial activity against Pseudomonas aeruginosa (MICs = 4-32 μM). The overall findings suggest optimal routes to balancing peptide hydrophobicity and charge distribution that allow efficient penetration and disruption of the bacterial membranes without damage to mammalian (host) membranes.

PMID:
22253439
[PubMed - as supplied by publisher]
Free full text
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14.
Endocrinology. 2012 Jan 17. [Epub ahead of print]

Disruption of the Murine Glp2r Impairs Paneth Cell Function and Increases Susceptibility to Small Bowel Enteritis.

Source

Department of Medicine, Mt. Sinai Hospital, Samuel Lunenfeld Research Institute (S.-J.L., J.L., K.K.L., D.H., B.Y., D.J.D.), and the Department of Cell and Systems Biology (H.M., D.S.G.), University of Toronto, Toronto Ontario, Canada M5G 1X5.

Abstract

Exogenous glucagon-like peptide-2 receptor (GLP-2R) activation elicits proliferative and cytoprotective responses in the gastrointestinal mucosa and ameliorates experimental small and large bowel gut injury. Nevertheless, the essential physiological role(s) of the endogenous GLP-2R remain poorly understood. We studied the importance of the GLP-2R for gut growth, epithelial cell lineage allocation, the response to mucosal injury, and host-bacterial interactions in Glp2r(-/-) and littermate control Glp2r(+/+) mice. Glp2r(-/-) mice exhibit normal somatic growth and preserved small and large bowel responses to IGF-I and keratinocyte growth factor. However, Glp2r(-/-) mice failed to up-regulate intestinal epithelial c-fos expression in response to acute GLP-2 administration and do not exhibit changes in small bowel conductance or small or large bowel growth after administration of GLP-2R agonists. The crypt and villus compartment and the numbers and localization of Paneth, enteroendocrine, and goblet cells were comparable in Glp2r(+/+) vs. Glp2r(-/-) mice. Although the severity and extent of colonic mucosal injury in response to 3% oral dextran sulfate was similar across Glp2r genotypes, Glp2r(-/-) mice exhibited significantly increased morbidity and mortality and increased bacterial translocation after induction of enteritis with indomethacin and enhanced mucosal injury in response to irinotecan. Moreover, bacterial colonization of the small bowel was significantly increased, expression of Paneth cell antimicrobialgene products was reduced, and mucosal bactericidal activity was impaired in Glp2r(-/-) mice. Although the Glp2r is dispensable for gut development and the response to colonic injury, Glp2r(-/-) mice exhibit enhanced sensitivity to small bowel injury, and abnormal host-bacterial interactions in the small bowel.

PMID:
22253424
[PubMed - as supplied by publisher]
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15.
Antimicrob Agents Chemother. 2012 Jan 17. [Epub ahead of print]

Pharmacological inhibition of the ClpXP protease increases bacterial susceptibility to host cathelicidin antimicrobial peptides and cell-envelope active antibiotics.

Source

Department of Biology, Texas Christian University, Fort Worth, TX 76129.

Abstract

The ClpXP protease is a critical bacterial intracellular protease that regulates protein turnover in many bacterial species. Here we identified a pharmacological inhibitor of the ClpXP protease, F2, and evaluated its action in Bacillus anthracis and Staphylococcus aureus. We found that F2 exhibited synergistic antimicrobial activity with cathelicidin antimicrobialpeptides and antibiotics that target the cell well and/or cell membrane such as penicillin and daptomycin in B. anthracis and drug resistant strains of S. aureus. ClpXP inhibition represents a novel therapeutic strategy to simultaneously sensitize pathogenic bacteria to host defenses and pharmaceutical antibiotics.

PMID:
22252821
[PubMed - as supplied by publisher]
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16.
Antimicrob Agents Chemother. 2012 Jan 17. [Epub ahead of print]

The natural antimicrobial peptide subtilosin acts synergistically with glycerol monolaurate, lauric arginate and {varepsilon}-poly-L-lysine against bacterial vaginosis-associated pathogens but not human lactobacilli.

Source

Rutgers, The State University of New Jersey, USA.

Abstract

Subtilosin is a cyclical antimicrobial peptide produced by Bacillus amyloliquefaciens that has antimicrobial activity against the bacterial vaginosis-associated human pathogen Gardnerella vaginalis. The ability of subtilosin to inhibit G. vaginalis alone and in combination with the natural antimicrobials glycerol monolaurate (Lauricidin®), lauric arginate and ε-poly-L-lysine was tested using a checkerboard approach. Subtilosin was found to synergize with all of the chosen antimicrobials. These promising results indicate that lower concentrations of subtilosin in combination with other compounds could effectively be used to inhibit growth of the pathogen, thereby decreasing the risk of developedantimicrobial resistance. This is the first report on the effects of subtilosin combined with other natural antimicrobials against G. vaginalis.

PMID:
22252803
[PubMed - as supplied by publisher]
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17.
J Antibiot (Tokyo). 2012 Jan 18. doi: 10.1038/ja.2011.120. [Epub ahead of print]

Identification, synthesis and characterization of a novel antimicrobial peptideHKPLP derived from Hippocampus kuda Bleeker.

Source

State Key Laboratory of Biocontrol, Guangdong Province Key Laboratory of Pharmaceutical Functional Genes, National Engineering Research Center of South China Sea Marine Biotechnology, Department of Biochemistry, College of Life Sciences, Sun Yat-sen University, Guangzhou, China.

Abstract

A novel gene encoding 55 amino-acid residues has been identified from the brooding pouch cDNA library of Hippocampus kuda Bleeker. The deduced amino-acid sequence is highly homologous to several pleurocidin-likepeptides from the winter flounder and comprises a signal peptide, a pro-peptide and a mature peptide. The glycine-rich mature peptide, designated HKPLP, contains 24 amino-acid residues and has been synthesized by solid-phase peptidesynthesis. The purified HKPLP exhibits antimicrobial activity against several Gram-positive and Gram-negative bacterial strains at low concentrations (MIC 1.5-7.5 μM). Thermal stability assay data show good heat stability. CD spectroscopy experiments indicate that the dominant contents are anti-parallel and parallel sheets, which may have β-sheet or β-strand motif. It is inferred that HKPLP participates in the host defense during egg fertilization and embryo development as an antimicrobial peptide in brooding pouch.The Journal of Antibiotics advance online publication, 18 January 2012; doi:10.1038/ja.2011.120.

PMID:
22252202
[PubMed - as supplied by publisher]
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18.
Br J Nutr. 2012 Jan 17:1-8. [Epub ahead of print]

Dose-response effects of an antimicrobial peptide, a cecropin hybrid, on growth performance, nutrient utilisation, bacterial counts in the digesta and intestinal morphology in broilers.

Source

School of Life Science, Sun Yat-Sen University, Guangzhou 510275, People's Republic of China.

Abstract

The aim of the present study was to evaluate the feasibility of an antimicrobial peptide, cecropin A(1-11)-D(12-37)-Asn (CADN), as an alternative to antibiotic growth promoter (AGP) in poultry diets. A total of 1500 14-d-old indigenous male chickens (222 (sd 13) g) were randomly allocated to five groups with five replicate cages of sixty birds each, and fed ad libitum five grower diets and subsequently five finisher diets for 14 d each. The diets were made up by supplementing their basal diets with a CADN liquid sample (CADNL) at 0, 2, 4, 6 and 8 ml/kg, respectively. During the feeding period, a metabolic experiment was carried out to determine the apparent digestibility of diethyl ether extract, nitrogen retention and apparent metabolisable energy of the diet sample fed to each cage of chicks. At the end of the feeding experiment, one chick from each cage was killed for bacteriological, light microscopic and scanning electron microscopic examination of the intestinal villi. CADN had a negative linear, positive quadratic and negative linear effect on feed intake (F), weight gain (G) and feed:gain ratio (F:G), respectively, for the growers; it had a quadratic effect on F, G or F:G for the finishers; it increased nutrient utilisation for both growers and finishers; it decreased aerobic bacterial counts in both jejunal and caecal digesta in a dose-dependent manner; it enhanced intestinal villus heights in a dose-dependent manner and made the duodenum villi of the CADNL8 group at 42 d appear as a netted leaf-like structure. CADN is therefore a possible alternative to AGP in broiler feeds.

PMID:
22251659
[PubMed - as supplied by publisher]
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19.
Environ Entomol. 2011 Jun;40(3):669-78.

Inhibition of microorganisms on a carrion breeding resource: the antimicrobialPeptide activity of burying beetle (coleoptera: silphidae) oral and anal secretions.

Source

Department of Biological Sciences, Idaho State University, 921 S. 8th Ave. Stop 8007, Pocatello, ID 83209, USA.

Abstract

Competition between scavengers and microorganisms for the nutrients within carrion is well documented. As a significant contributor to food web energetics, carrion serves not only as a food source for scavengers, but also as a reproductive resource for many insects. One example are the burying beetles of the Nicrophorus genus (Coleoptera: Silphidae) whose reproduction is dependent on locating and successfully sequestering vertebrate carrion. Throughout the cooperative preparation of carrion and feeding of the larval offspring, parental beetles coat the carrion with oral and anal secretions known to attenuate the growth of molds and bacteria in the laboratory. We test the hypotheses that Nicrophorus secretions attenuate the growth of naturally occurring microorganisms likely to be found colonizing the carrion resource, and that the active antimicrobial components of the secretions are small antimicrobial peptides(AMPs) similar to those produced by other insects.

PMID:
22251646
[PubMed - in process]
20.
Biochem Cell Biol. 2012 Jan 17. [Epub ahead of print]

Influence of specific amino acid side-chains on the antimicrobial activity and structure of bovine lactoferrampin (1) (1) This article is part of Special Issue entitled Lactoferrin and has undergone the Journal's usual peer review process.

Source

a University of Calgary, Department of Biological Sciences, 2500 University Drive NW, Calgary, AB T2N 1N4, Canada.

Abstract

Lactoferrin is an 80 kDa iron binding protein found in the secretory fluids of mammals and it plays a major role in host defence. An antimicrobial peptide, lactoferrampin, was identified through sequence analysis of bovine lactoferrin and itsantimicrobial activity against a wide range of bacteria and yeast species is well documented. In the present work, the contribution of specific amino acid residues of lactoferrampin was examined to evaluate the role that they play in membrane binding and bilayer disruption. The structures of all the bovine lactoferrampin derivatives were examined with circular dichroism and nuclear magnetic resonance spectroscopy, and their interactions with phospholipids were evaluated with differential scanning calorimetry and isothermal titration calorimetry techniques. From our results it is apparent that the amphipathic N-terminal helix anchors the peptide to membranes with Trp 268 and Phe 278 playing important roles in determining the strength of the interaction and for inducing peptide folding. In addition, the N-terminal helix capping residues (DLI) increase the affinity for negatively charged vesicles and they mediate the depth of membrane insertion. Finally, the unique flexibility in the cationic C-terminal region of bovine lactoferrampin does not appear to be essential for the antimicrobial activity of the peptide.

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