Gene transfer with poly-melittin peptides.

The 26 amino acid hemolytic melittin peptide was converted into a gene transfer peptide that binds to DNA and polymerized through disulfide bond formation. Melittin analogues were synthesized by the addition of one to four Lys repeats at either the C- or the N-subterminal end along with terminal Cys residues. Melittin analogues were able to bind and polymerize on plasmids resulting in the formation of DNA condensates. In the absence of DNA, melittin analogues retained their red blood cell hemolytic potency but were inactive when bound to plasmid DNA. The in vitro gene transfer efficiency mediated by poly-melittin analogues was equivalent to PEI in HepG2 cells. Attempts to truncate portions of either of the two melittin alpha-helices resulted in concurrent loss of hemolytic potency and gene transfer efficiency. The results demonstrate the ability to transform melittin into a gene transfer peptide by transiently masking its membrane lytic activity by the addition of Lys and Cys residues to promote DNA binding and polymerization.