Genes involved in protein glycosylation determine the activity and cell internalization of the antifungal peptide PAF26 in Saccharomyces cerevisiae

•Fungal protein glycosylation affects the antifungal action of the cell-penetrating peptide PAF26.•S.cerevisiae mutants in genes PMT1-6, EOS1, ALG5, MNN1, MNN4 and MNN5 are tolerant to PAF26.•Blockage of PAF26 internalization in the Δeos1 mutant increased cell viability.•Enzymatic removal of the cell wall inhibited the internalization and killing of PAF26. We have previously characterized the synthetic hexapeptide PAF26 as a cell-penetrating and non-lytic antifungal peptide that is active against Saccharomyces cerevisiae and filamentous fungi. Numerous cell wall (CW) proteins are glycosylated in fungi and many of these play important roles in fungal pathogenesis. In this study, we screened a collection of S. cerevisiae deletion mutants for protein glycosylation genes whose deletion altered the sensitivity to PAF26. Increased tolerance to PAF26 was observed in mutants with the following disrupted genes: PMT1-6, EOS1, ALG5, MNN1, MNN4 and MNN5. Significantly, genes coding for protein O-mannosyltransferase 2 (Pmt2p), which is responsible for the addition of the first mannosyl residue of O-linked carbohydrates, and for Eos1p, an enzyme involved in N-linked glycosylation of proteins, showed resistance to PAF26 and defects in CW integrity. Microscopic studies on the S. cerevisiae Δeos1 deletion mutant demonstrated a blockage of peptide internalization by cells. Protoplasts lacking CWs interacted with the peptide, but were more resistant to peptide killing than cells possessing CWs due to a blockage in PAF26 internalization. Interestingly, protoplasts obtained from Δeos1 behaved similarly to those of the parental strain. Collectively, these observations demonstrate that the CW is a positive factor that determines the internalization of the PAF26, and that Eos1p exerts its activity through the glycosylation of specific protein(s) involved in peptide internalization.