McMillan KAM and Coombs MRP (2020), Review: Examining the Natural Role of Amphibian...

XB-ART-57564

Molecules 2020 Nov 20;2522:. doi: 10.3390/molecules25225436.

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Review: Examining the Natural Role of Amphibian Antimicrobial Peptide Magainin.

McMillan KAM , Coombs MRP .

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Host defense peptides (HDPs) are a group of antimicrobial peptides (AMPs) that are crucial components of the innate immune system of many different organisms. These small peptides actively kill microbes and prevent infection. Despite the presence of AMPs in the amphibian immune system, populations of these organisms are in decline globally. Magainin is an AMP derived from the African clawed frog (Xenopus laevis) and has displayed potent antimicrobial effects against a wide variety of microbes. Included in this group of microbes are known pathogens of the African clawed frog and other amphibian species. Arguably, the most deleterious amphibious pathogen is Batrachochytrium dendrobatidis, a chytrid fungus. Investigating the mechanism of action of magainin can help understand how to effectively fight off infection. By understanding amphibian AMPs' role in the frog, a potential conservation strategy can be developed for other species of amphibians that are susceptible to infections, such as the North American green frog (Rana clamitans). Considering that population declines of these organisms are occurring globally, this effort is crucial to protect not only these organisms but the ecosystems they inhabit as well.

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Genes referenced: magainins rad51

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References [+] :

Bechinger, Structure and orientation of the antibiotic peptide magainin in membranes by solid-state nuclear magnetic resonance spectroscopy. 1993, Pubmed, Xenbase

	Figure 1. Membrane permeation by the carpet model. Antimicrobial peptides (AMPs) are indicated by pink helices. Image created with BioRender.com.
	Figure 2. Membrane permeation by the toroidal pore model. AMPs are indicated by green helices. Image created with BioRender.com.
	Figure 3. Amino acid sequence of magainin I and magainin II [36]. Two locations of mismatched amino acids on the peptide sequence are highlighted in yellow.
	Figure 4. Helical wheel (a) and net diagrams (b) of magainin I [42]. Amino acids are indicated by their single-letter abbreviations and are categorized according to the following colors: polar basic (red), polar acidic (blue), polar uncharged (green), nonpolar (yellow). Both the wheel and net diagrams demonstrate the division of hydrophobic and hydrophilic components of the peptide. The helical wheel diagram was generated using online software called NetWheels [43] and the net diagram was made using Microsoft PowerPoint.
	Figure 5. Role of the AMP magainin in the African clawed frog in the defense against amphibian pathogens. The peptide is located in the dermis of the African clawed frog skin and conforms into an alpha helix upon interacting with a negatively charged membrane, resulting in the formation of toroidal pores in most instances. The peptide interferes with internal metabolic processes by activating the RecA gene, which causes DNA fragmentation [41]. This ultimately kills the pathogen. Image created with BioRender.com.