Under this view, an attractive hypothesis that needs to be tested is that the different CW proteins identified in ours and previous studies reflect differences in the interaction of distinct AMP with the cell envelope [30, 33]. Involvement

of the IPT1 gene in AMP sensitivity A noteworthy mutant with a marked increased resistance to PAF26 was Δipt1 (Figure 5C). Sphingolipids are essential components of the plasma membrane in all eukaryotic cells and IPT1p catalyzes the last step in the biosynthesis of the fungal sphingolipid M(IP)2C. Previous works with the Δipt1 mutant showed high resistance to DmAMP1, an antifungal plant defensin, and lower peptide binding to the yeast surface than the wild-type strain [16]. The authors proposed that DmAMP1 interacts with this sphingolipid to exert the antifungal action [69]. In addition, mutants lacking the IPT1 Ruxolitinib molecular weight gene also showed resistance to syringomycin E [58]. We found that the Δipt1 strain was resistant to PAF26 (Figure 5C) but bound FITC-PAF26 to the same extent as the parental strain (Figure 8), in contrast to what was reported in the plant defensin example. This apparent contradiction could be explained considering that the initial binding of PAF26 to the fungal cell occurs at the CW, and not at the plasma membrane. Also remarkably, Δipt1 resistance to PAF26 is coincident

with extreme sensitivity to the membrane perturbing SDS (Figure 5C). This differential Dabrafenib price behaviour was unique among the strains analyzed in our study. It neatly demonstrates that although interaction is the first step in the antimicrobial mechanism of peptides, other additional susceptibility factors exist since an abnormal membrane and/or weakened CW does not always lead to higher susceptibility to PAF26 and other antimicrobial peptides/proteins. Overall, the data indicate that involvement of IPT1 and

presence of M(IP)2C in the yeast plasma membrane could be a common factor for distinct AMP to exert their action onto S. cerevisiae. Intracellular Glycogen branching enzyme effects of PAF26 An overlapping response to distinct AMP seems to be related to DNA breakdown and/or induction of apoptosis [23, 24, 33]. No significant annotation related to DNA damage or apoptosis was found in our GO analyses (Additional File 4). However, the gene with the highest induction (around 10-fold) by both peptides was PSO2, which was not identified in any of the previous studies. It is highly induced after DNA strand breaks and binds damaged DNA. On the other hand, the DNA ligase gene DNL4 required for non-homologous end-joining (NHEJ) and repair of dsDNA breaks is among the most repressed by both peptides. Strikingly, LDB7 also involved in NHEJ was the only gene repressed by two unrelated AMP [33], demonstrating that independent studies point to the same processes even though they identify distinct individual genes. We have previously shown that both PAF26 and melittin share with other cationic AMP the capacity to bind nucleic acids in vitro [33, 46, 70].