Interaction of Polyamine-modified Marine Peptide Aculeine A with Cell Membranes: Disruption or Entry

Aculeine A (ACU-A, 1), a marine sponge-derived peptide toxin with a novel posttranslational modification with long-chain polyamine (LCPA), exerts potent hemolytic and cytotoxic activity against mammalian erythrocytes and cultured cells, respectively. Here we found that toxic actions of 1 were attenuated by negatively charged phospholipids and glycosaminoglycans (GAGs) suggesting that 1 interacts primarily with cell surfaces through ionic interactions. In HeLa cells, 1 induced cytotoxicity with characteristic membrane blebbing at 37 °C, while the treatment at 4 °C did not show such adverse phenotype. The immunohistochemical and mass spectral experiments together showed that 1 penetrated cell membrane and localized in the cytosol efficiently at 37 °C but not at 4 °C, suggesting that the intracellular translocation of 1 requires some energy-dependent cellular process. These results together suggested that 1 could act either as a membrane disrupting or a cell penetrating agent depending on cell types. Aculeine-A (1), a sponge-derived hemolytic and cytotoxic peptide with long chain polyamine interacts with negatively charged cell surface species by ionic interactions. Here, we show that 1 internalized in the cells in an energy dependent manner. Thereby 1 is a naturally occurring cell penetrating peptide (CPP) with unique structural motif.