Antimicrobial peptides

About: Antimicrobial peptides is a research topic. Over the lifetime, 10645 publications have been published within this topic receiving 507688 citations. The topic is also known as: host defense peptide & antimicrobial protein.

PhoP-PhoQ activates transcription of pmrAB, encoding a two-component regulatory system involved in Salmonella typhimurium antimicrobial peptide resistance.

Abstract: Antimicrobial cationic peptides are a host defense mechanism of many animal species including mammals, insects, and amphibians. Salmonella typhimurium is an enteric and intracellular pathogen that interacts with antimicrobial peptides within neutrophil and macrophage phagosomes and at intestinal mucosal surfaces. The Salmonella spp. virulence regulators, PhoP and PhoQ, activate the transcription of genes (pag) within macrophage phagosomes necessary for resistance to cationic antimicrobial peptides. One PhoP-activated gene, pagB, forms an operon with pmrAB (5' pagB-pmrA-pmrB 3'), a two-component regulatory system involved in resistance to the antimicrobial peptides polymyxin, azurocidin (CAP37), bactericidal/permeability-increasing protein (BPI or CAP57), protamine, and polylysine. Expression of pmrAB increased transcription of pagB-pmrAB by activation of a promoter 5' to pagB. pmrAB is also expressed from a second promoter, not regulated by PhoP-PhoQ or PmrA-PmrB, located within the pagB coding sequence. S. typhimurium strains with increased pag locus expression were demonstrated to be polymyxin resistant because of induction of pagB-pmrAB; however, PmrA-PmrB was not responsible for the increased sensitivity of PhoP-null mutants to NP-1 defensin. Therefore, PhoP regulates at least two separate networks of genes responsible for cationic antimicrobial peptide resistance. These data suggest that resistance to the polymyxin-CAP family is controlled by a cascade of regulatory protein expression that activates transcription upon environmental sensing.

A Family of IFN-γ–Inducible 65-kD GTPases Protects Against Bacterial Infection

Abstract: Immune interferon gamma (IFN-γ) is essential for mammalian host defense against intracellular pathogens. IFN-γ induces nearly 2000 host genes, yet few have any assigned function. Here, we examined a complete mouse 65-kilodalton (kD) guanylate-binding protein (Gbp) gene family as part of a 43-member IFN-γ-inducible guanosine triphosphatase (GTPase) superfamily in mouse and human genomes. Family-wide loss-of-function analysis found that at least four Gbps--Gbp1, Gbp6, Gbp7, and Gbp10--conferred cell-autonomous immunity to listerial or mycobacterial infection within macrophages and gene-deficient animals. These Gbps solicited host defense proteins, including the phagocyte oxidase, antimicrobial peptides, and autophagy effectors, to kill intracellular bacteria. Thus, specific 65-kD Gbps coordinate a potent oxidative and vesicular trafficking program to protect the host from infection.

Insect antimicrobial peptides: structures, properties and gene regulation.

Abstract: Antimicrobial peptides (AMPs) are part of the armament that insects have developed to fight off pathogens. Insect AMPs are typically cationic and often made of less than 100 amino acid residues. Although their structures are diverse, most of the AMPs can be assigned to a limited number of families. The most common structures are represented by peptides assuming a alpha-helical conformation in organic solutions or disulfide-stabilized beta-sheets with or without alpha-helical domains present. The diverse activity spectrum of these peptides may indicate different modes of action. Genetic analysis in the Drosophila model evidenced that multiple signal transduction pathways are activating the genes coding AMPs.

Antimicrobial peptides for therapeutic applications: a review.

Abstract: Antimicrobial peptides (AMPs) have been considered as potential therapeutic sources of future antibiotics because of their broad-spectrum activities and different mechanisms of action compared to conventional antibiotics Although AMPs possess considerable benefits as new generation antibiotics, their clinical and commercial development still have some limitations, such as potential toxicity, susceptibility to proteases, and high cost of peptide production In order to overcome those obstacles, extensive efforts have been carried out For instance, unusual amino acids or peptido-mimetics are introduced to avoid the proteolytic degradation and the design of short peptides retaining antimicrobial activities is proposed as a solution for the cost issue In this review, we focus on small peptides, especially those with less than twelve amino acids, and provide an overview of the relationships between their three-dimensional structures and antimicrobial activities The efforts to develop highly active AMPs with shorter sequences are also described