Aromatic residue-rich amino-terminal segments of temporin L self-assemble into collagen-mimetic peptides with cell-adhesion properties.

Intriguingly, 13-mer frog-peptide, temporin L (TempL) contains 50% aromatic residues within its first eight residues. Considering the role of aromatic residues in self-assembly of peptides and the potential of such peptides in biomedical applications, we envisaged to identify new short self-assembling peptides from the amino-terminus of TempL and characterize their structural and biological properties. Thus, starting from the eighth to the first residue of TempL, we synthesized five 4 to 8 residue peptides (T-4mer to T-8mer). Different ultrastructural studies suggested nano-spherical/nano-fibrillar structures of these peptides. Remarkably, T-6mer, T-7mer and T-8mer exhibited polyproline type-II circular dichroism spectra of collagen-like triple-helical structure and sigmoidal melting curves like that we observed with rat-tail type-I collagen. Amazingly, the T-8mer peptide at 1.5% (w/v) forms hydrogel within an hour indicating its ability to form supramolecular assembly, saturated with water. We further studied collagen-mimetic nature of these TempL-derived peptides. HepG2 cells showed significant adhesions onto the coatings of T-6mer, T-7mer, T-8mer peptides and rat-tail type-I collagen which got compromised when these cells were pre-treated with antibody of collagen receptor, integrin α2β1. Interestingly, following the adhesions onto the surface of these TempL-derived peptides, cytoskeletal organization was induced in HepG2 cells like that observed in the presence of a collagen protein. Overall, the current results demonstrated the dissection of a frog-peptide, TempL with revelation of collagen-mimetic peptides from its aromatic-residue rich amino-terminus.