(386b) Translocation of Cell-Penetrating Peptides into Fungal Cells

Cell-penetrating peptides (CPPs) are small peptides that can cross cellular membranes and carry cargo into cells. Although the interactions of CPPs with mammalian cells have been widely studied, much less is known about their interactions with fungal cells. We have studied the translocation of a number of peptides into the human fungal pathogen Candida albicans using a combination of simulations and experiments. We have shown that the mechanisms of translocation vary by peptide and include both endocytic mechanisms and direct translocation. To study how net charge and hydrophobicity of CPPs affect translocation into fungal cells, we designed variants of the peptides pVEC and SynB with altered levels of charge and hydrophobicity and evaluated translocation into C. albicans. Charge played a greater role in translocation efficiency of the peptides than hydrophobicity, with a higher level of charge leading to higher level of translocation into C. albicans and a higher level of cytosolic localization. Hydrophobicity had little effect on translocation efficiency, but a low level of hydrophobicity did lead to increased vacuolar localization and an energy-dependent translocation mechanism. Our results suggest that CPPs can be designed for desired levels of cargo delivery into fungal cells and for desired translocation mechanisms, which will provide useful insight as new CPPs are designed to specifically target fungal cells.