Translocation of analogues of the antimicrobial peptides magainin and buforin across XXXX cell membranes.

@entity1 @entity137 @entity2622 @entity5
Cationic antimicrobial peptides play important roles in innate immunity. Compared with extensive studies on peptide-bacteria interactions, little is known about peptide- @entity1 cell interactions. Using @entity1 @entity2622 HeLa and fibroblastic TM12 cells, we investigated the cellular uptake of fluorescent analogues of the two representative antimicrobial peptides magainin 2 and buforin 2 in comparison with the representative Arg-rich cell-penetrating Tat-(47-57) peptide (YGRKKRRQRRR). The dose, time, temperature, and energy dependence of translocation suggested that the three peptides cross cell membranes through different mechanisms. The magainin peptide was internalized within a time scale of tens of minutes. The cooperative concentration dependence of uptake suggested that the peptide forms a pore as an intermediate similar to the observations in model membranes. Furthermore, the translocation was coupled with @entity137 , which was larger for @entity5 HeLa cells. In contrast, the buforin peptide translocated within 10 min by a temperature-independent, less concentration-dependent passive mechanism without showing any significant @entity137 at the highest concentration investigated (100 microm). The uptake of the Tat peptide was proportional to the peptide concentration, and the concentration dependence was lost upon ATP depletion. The peptide exhibited a moderate @entity137 at higher concentrations. The time course did not show saturation even after 120 min. The buforin peptide, covalently attached to the 28-kDa green fluorescent protein, also entered cells, suggesting a potency of the peptide as a vector for macromolecular delivery into cells. However, the mechanism appeared to be different from that of the parent peptide.
