An amphibian-derived, cationic, ?-helical antimicrobial peptide kills yeast by caspase-independent but AIF-dependent programmed cell death

Centre for Biomolecular Sciences, School of Biology, University of St. Andrews, The North Haugh, St. Andrews, KY16 9ST, UK.
Molecular Microbiology (Impact Factor: 4.42). 08/2007; 65(2):494-507. DOI: 10.1111/j.1365-2958.2007.05801.x
Source: PubMed


The dermaseptins are a family of antimicrobial peptides from the tree-frog Phyllomedusa sauvagii. Yeast exposed to dermaseptin S3(1-16), a truncated derivative of dermaseptin S3 with full activity, showed diagnostic markers of yeast apoptosis: the appearance of reactive oxygen species and fragmentation of nuclear DNA. This process was independent of the yeast caspase, Yca1p. Screening of a non-essential gene deletion collection in yeast identified genes that conferred resistance to dermaseptin S3(1-16): izh2Delta, izh3Delta, stm1Delta and aif1Delta, all known to be involved in regulating yeast apoptosis. The appearance of apoptotic markers was reduced in these strains when exposed to the peptide. Dermaseptin S3(1-16) was shown to interact with DNA, and cause DNA damage in vivo, a process known to trigger apoptosis. Supporting this, a dermaseptin S3(1-16) affinity column specifically purified Stm1p, Mre11p and Htb2p; DNA-binding proteins implicated in yeast apoptosis and DNA repair. Thus, amphibians may have evolved a mechanism to induce cell suicide in invading fungal pathogens.

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Available from: Peter J Coote, Sep 23, 2014
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    • "Production of reactive oxygen species (ROS) was assessed to examine secondary effects of polyenes. Cultures were treated overnight with 0.5 or 1.0 μg ml−1 amphotericin B and ROS was detected by a previously described method using 2,7-dichlorofluorescein (Sigma Aldrich, St Louis, MO, USA) [7]. "
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    ABSTRACT: Background There is a pressing need to identify novel antifungal drug targets to aid in the therapy of life-threatening mycoses and overcome increasing drug resistance. Identifying specific mechanisms of action of membrane-interacting antimicrobial drugs on the model fungus Saccharomyces cerevisiae is one avenue towards addressing this issue. The S. cerevisiae deletion mutants Δizh2, Δizh3, Δaif1 and Δstm1 were demonstrated to be resistant to amphibian-derived antimicrobial peptides (AMPs). The purpose of this study was to examine whether AMPs and polyene antifungals have a similar mode of action; this was done by comparing the relative tolerance of the mutants listed above to both classes of antifungal. Findings In support of previous findings on solid media it was shown that Δizh2 and Δizh3 mutants had increased resistance to both amphotericin B (1–2 μg ml−1) and nystatin (2.5 – 5 μg ml−1) in liquid culture, after acute exposure. However, Δaif1 and Δstm1 had wild-type levels of susceptibility to these polyenes. The generation of reactive oxygen species (ROS) after exposure to amphotericin B was also reduced in Δizh2 and Δizh3. These data indicated that polyene antifungal and AMPs may act via distinct mechanisms of inducing cell death in S. cerevisiae. Conclusions Further understanding of the mechanism(s) involved in causing cell death and the roles of IZH2 and IZH3 in drug susceptibility may help to inform improved drug design and treatment of fungal pathogens.
    Annals of Clinical Microbiology and Antimicrobials 05/2014; 13(1):18. DOI:10.1186/1476-0711-13-18 · 2.19 Impact Factor
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    • "Most antimicrobial peptides bind nucleic acids (DNA and RNA) in vitro (Castle et al., 1999; Subbalakshmi and Sitaram, 1998; Boman et al., 1993), indicating that disruption of cell membranes might be combined with inhibition of DNA synthesis, transcription and/or RNA translation. Interestingly, S. cerevisiae proteins involved in DNA repair were purified as partners of dermaseptin S3, contributing to the understanding of its induction of apoptosis in yeast (Morton et al., 2007). The pea defensin PSD1 was shown to locate inside the nucleus of the model fungus Neurospora crassa, wherein it might alter cell cycle progression (Lobo et al., 2007). "
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    Tissue and Cell 06/2013; 45(5). DOI:10.1016/j.tice.2013.04.003 · 1.25 Impact Factor
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    • "A recent study has shown that dermaseptins might have evolved a mechanism to induce the death of the cell during the invasion of fungal pathogens. It was found that when yeast was exposed to dermaseptin S 3 (1–16), a truncated derivative of dermaseptin S 3 with full activity, there were diagnostic markers of apoptosis, namely the appearance of reactive oxygen species and the fragmentation of nuclear DNA [Morton et al., 2007a,b]. However, many of dermaseptins are inactive on normal eukaryotic cells. "
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