The Dry Preservation of Giant Vesicles Using a Group 3 LEA Protein Model Peptide and Its Molecular Mechanism

Abstract

Abstract We here focus on whether a model peptide for Group 3 LEA (G3LEA) proteins can be used for the dry preservation of vesicles whose size and phospholipid compositions resemble those of living cells. For this purpose, we prepared a peptide called PvLEA-22, which consists of two tandem repeats of the 11-mer motif characteristic of G3LEA proteins from an African sleeping chironomid, and giant vesicles (diameter 6–9 µm) prepared with egg phosphatidylcholine. We examined the particle size distribution of the vesicles before and after drying and rehydration in the presence of the peptide. The model peptide suppressed desiccation-induced disruption of the giant vesicles in a concentration-dependent manner with an efficiency comparable to that of trehalose, a well-known desiccation protectant. To elucidate the underlying mechanism of the peptide’s protective function, we performed molecular dynamics (MD) simulations for model systems composed of the peptide PvLEA-22 and a 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine (POPC) bilayer. The results indicate that Lys residues in PvLEA-22 interact with the bilayer surface, where their positively charged side chains, -(CH2)4NH3+, directly hydrogen bond (H-bond) with nearby phospholipid headgroups. On the basis of these results, we discuss the possible mechanisms for the protective effect of the peptide on dried vesicles.