Location of peptide assembly determines the death mechanism

Abstract

Peptide sequence can be designed to form supramolecular structure such as fiber, tube and vesicle structure via self-assembly. When each peptide monomer and their aggregated state reach to equilibrium state, self-assembly process was occurred. Therefore, the concentration is the critical controllable factor to induce assembly. Self-assembly appears when molecules achieve critical aggregation concentration,CAC. In living cells, designed molecules form the self-assembly structure over the CAC inside targeted organelle then it induce the severe damage to cell. Our group previously made the amphiphilc peptide, Mito-FF. It was designed to accumulate in mitochondria. The sequence of Mito-FF is 'Pyrenebutryic acid-FFK-TPP'. Diphenylalanine(FF) form the β-sheet domain, triphenylphosphonium(TPP) is the mitochondria targeting moiety it was conjugated on lysine. We chose the target organelle as mitochondria because mitochondria has important role in metabolism, regulator of cell death. And pyrene as a fluorescence group to observe uptake on mitochondria.To understand how small molecule conjugated to N-terminal on peptide sequence can affects to cell death, 5 small molecule was used for synthesize Mito-FF based peptides. Octanoic acid, palmitic acid, pefluorooctanoic acid, nitrobenzodiazole(NBD), naphthalene tetracarboxlyic dianhydride was used. Especially, Palmitic acid showed different tendency compare to Mito-FF. Mito-FF is known as induce apoptosis.In contrast, palmitic acid(C16) conjugated FFK-TPP molecule induced necrosis. To observe this different death mechanism, we synthesized C16-FFK(NBD)K(TPP) andPyrenebutryic acid-FFK(NBD)K(TPP). NBD dye was selected for confocal microscopy. Two product was incubated both cancer cell(HeLa) and normal cell(NIH-3T3).