Project description:The mammalian gut secretes a family of multifunctional peptides that affect appetite, intestinal secretions, and motility, while some regulate the microbiota. We report peptide YY (PYY1-36), but not endocrine PYY3-36, is an antimicrobial peptide (AMP) expressed by gut epithelial Paneth Cells (PC). PC-PYY has limited antibacterial activity, but shows selective activity against virulent hyphal, but not yeast forms, of Candida albicans. 5 PC-PYY is a cationic molecule that interacts with the anionic surfaces of fungal hyphae to cause membrane disruption and transcriptional reprogramming to maintain the yeast phenotype of the fungus. PC-PYY is packaged into secretory granules and is secreted into and retained by surface mucus, which optimizes PC-PYY activity. Hence, PC-PYY acts as a selective antifungal AMP that contributes to the maintenance of gut fungal commensalism.
Project description:It is well appreciated that reactive oxygen species (ROS) are deleterious to mammals, including humans, especially when generated in abnormally large quantities from cellular metabolism. Whereas the mechanisms leading to the production of ROS are rather well delineated, the mechanisms underlying tissue susceptibility or tolerance to oxidant stress remain elusive. Through an experimental selection over many generations, we have previously generated Drosophila melanogaster flies that tolerate tremendous oxidant stress and have shown that the family of antimicrobial peptides (AMP) is over-represented in these tolerant flies. Furthermore, we have also demonstrated that overexpression of even one AMP at a time (e.g. Diptericin) allows wild type flies to survive much better in hyperoxia. In the current study, we used a number of experimental approaches to investigate the potential mechanisms underlying hyperoxia tolerance in flies with antimicrobial peptide overexpression. We demonstrate that flies with Diptericin overexpression resist oxidative stress by increasing antioxidant enzyme activities and preventing an increase in ROS level after hyperoxia. Depleting the GSH pool using buthionine sulfoximine limits fly survival, thus confirming that enhanced survival observed in these flies is related to improved redox homeostasis. We conclude that a) AMPs play an important role in tolerance to oxidant stress; b) overexpression of Diptericin changes the cellular redox balance between oxidant and antioxidant, and c) this change in redox balance plays an important role in survival in hyperoxia. Expression profiles of Drosophila melanogaster with anti-microbial peptide over-expression (experimental sample; n=3) and controls (UAS-AMP alone not crossed to da-GAL4; n=3) were determined using Affymetrix Drosophila Genome 2.0 Arrays.
Project description:Analysis of undifferentiated keratinocytes or differentiated keratinocytes stimulated with or without human cathelicidin antimicrobial peptide (CAMP) LL37. Results provide insight into the biological effects of CAMP on human keratinocytes. NHEKs were divided into two groups; low calcium (0.05 mM) and high calcium condition (1.6 mM). Then keratinocytes were stimulated with human cathelicidin antimicrobial peptide LL37 at 0, 2.56, and 7.68 M-NM-<M for 12 h to 24 h.
Project description:Traditional medicinal plants are rich reservoirs of antimicrobial agents, including antimicrobial peptides (AMPs). Herein, Amaranthus tricolor AMPs predicted in silico are identified via proteomics profiling. Bottom-up proteomics identified seven novel peptides spanning three AMP classes including lipid transfer proteins, snakins and defensins. Characterization via top-down peptidomic analysis of Atr-SN1, Atr-DEF1, and Atr-LTP1 revealed unexpected proteolytic processing and enumerated disulfide bonds. These results highlight the potential for integrating AMP prediction algorithms with complementary -omics approaches to accelerate characterization of biologically relevant AMP peptidoforms.
Project description:Staphylococcus aureus is a leading cause of hospital-associated infections. In addition, highly virulent strains of methicillin-resistant S. aureus (MRSA) are currently spreading outside health care settings. Survival in the human host is largely defined by the ability of S. aureus to resist mechanisms of innate host defense, of which antimicrobial peptides form a key part especially on epithelia and in neutrophil phagosomes. Here we demonstrate that the antimicrobial-peptide sensing system aps of the standard community-associated MRSA strain MW2 controls resistance to cationic antimicrobial peptides. The core of aps-controlled resistance mechanisms comprised the D-alanylation of teichoic acids (dlt operon), the incorporation of cationic lysyl-phosphatidylglycerol (L-PG) in the bacterial membrane (mprF), and the vraF/vraG putative antimicrobial peptide transporter. Further, the observed increased production of L-PG under the influence of cationic antimicrobial peptides was accompanied by the up-regulation of lysine biosynthesis. In noticeable difference to the aps system of S. epidermidis, only selected antimicrobial peptides strongly induced the aps response. Heterologous complementation with the S. epidermidis apsS gene indicated that this is likely caused by differences in the short extracellular loop of ApsS that interacts with the inducing antimicrobial peptide. Our study shows that the antimicrobial peptide sensor system aps is functional in the important human pathogen S. aureus, significant interspecies differences exist in the induction of the aps gene regulatory response, and aps inducibility is clearly distinguishable from effectiveness towards a given antimicrobial peptide. Keywords: Wild type control vs treated vs mutant Wild type untreated in triplicate is compared to wild type treated in triplicate along with three mutants in triplicate with and without treatment of indolicidin, totalling 30 samples
Project description:Antimicrobial peptides (AMPs) are compounds with a variety of bioactive properties. Especially promising are their antibacterial activities, often towards drug-resistant pathogens. Across different AMP sources, AMPs expressed within plants are relatively underexplored, with a limited number of plant AMP families identified. Recently, we identified the novel AMPs CC-AMP1 and CC-AMP2 in ghost pepper plants (Capsicum chinense x frutescens), exerting promising antibacterial activity and not classifying into any known plant AMP family. Herein, AMPs related to CC-AMP1 and CC-AMP2 were identified within both Capsicum annuum and Capsicum baccatum. Targeted MS/MS experiments were performed to determine peptide sequences, guided by in silico AMP sequence predictions.
Project description:Obtaining an in depth understanding of the arms races between peptides comprising the innate immune response and bacterial pathogens is of fundamental interest and will inform the development of new antibacterial therapeutics. Many cationic antimicrobial peptides (AMPs) share a range of structural and physical features that have been linked to antibacterial activity and yet they vary dramatically in their potency towards the same bacterial target. We hypothesised that a whole organism view of AMP challenge on Escherichia coli could provide a sophisticated, bacterial perspective enabling understanding of how potency is linked to mode of action. We used a 1H NMR metabolomic approach to characterise the effect on E. coli of challenge with four structurally and physically related AMPs: magainin 2, pleurocidin, buforin II and a designed peptide comprising D-amino acids only. Sub-inhibitory conditions, where these peptides nevertheless induced a bacterial response, were identified enabling electron microscopic and transcriptomic analyses. Although some common features of the bacterial response to AMP challenge could be identified, the metabolomes, morphological changes and the vast majority of the changes in gene expression were specific to each AMP. We show the antibacterial mode of action of AMPs can be accurately predicted by comparing ontological profiles generated by transcriptomic analyses. The response of E. coli to AMP challenge is highly plastic, with the bacteria capable of deploying a multifaceted response adapted to the mode of action rather than the physical properties of the AMP.
Project description:Staphylococcus aureus is a leading cause of hospital-associated infections. In addition, highly virulent strains of methicillin-resistant S. aureus (MRSA) are currently spreading outside health care settings. Survival in the human host is largely defined by the ability of S. aureus to resist mechanisms of innate host defense, of which antimicrobial peptides form a key part especially on epithelia and in neutrophil phagosomes. Here we demonstrate that the antimicrobial-peptide sensing system aps of the standard community-associated MRSA strain MW2 controls resistance to cationic antimicrobial peptides. The core of aps-controlled resistance mechanisms comprised the D-alanylation of teichoic acids (dlt operon), the incorporation of cationic lysyl-phosphatidylglycerol (L-PG) in the bacterial membrane (mprF), and the vraF/vraG putative antimicrobial peptide transporter. Further, the observed increased production of L-PG under the influence of cationic antimicrobial peptides was accompanied by the up-regulation of lysine biosynthesis. In noticeable difference to the aps system of S. epidermidis, only selected antimicrobial peptides strongly induced the aps response. Heterologous complementation with the S. epidermidis apsS gene indicated that this is likely caused by differences in the short extracellular loop of ApsS that interacts with the inducing antimicrobial peptide. Our study shows that the antimicrobial peptide sensor system aps is functional in the important human pathogen S. aureus, significant interspecies differences exist in the induction of the aps gene regulatory response, and aps inducibility is clearly distinguishable from effectiveness towards a given antimicrobial peptide. Keywords: Wild type control vs treated vs mutant
Project description:Transcriptional profiling of MatA yeast cells exposed to a cationic antimicrobial peptide (Iztli peptide 1) for 3.5, 7, 15 and 30 min is compared with MatA yeast cells without the peptide