Structural characterization and biological properties of the amyloidogenic elastin-like peptide (VGGVG)3

Abstract

The peculiar and unique properties of elastin are due to the abundance of hydrophobic residues and of repetitive sequences as XGGZG (X, Z=V, L or A). Unexpectedly, these sequences not only provide elasticity to the whole protein, but are also able to form amyloid-like fibrils. Even though amyloid fibrils have been associated for a long time to the development of serious disorders as Alzheimer's disease, recent evidence suggests that toxicity may be related to oligomeric species or to pre-fibrillar intermediates, rather than to mature fibrils. In addition, a number of studies highlighted the potential of "bio-inspired" materials based on amyloid-like nanostructures. The present study has been undertaken with the aim to characterize a chemically synthesized elastin-like peptide (VGGVG)3. Structural and biological features were compared with those of peptides as poly(VGGVG) and VGGVG that, having the same amino acid sequence, but different length and supramolecular structure have been previously investigated for their amyloidogenic properties. Results demonstrate that a minimum sequence of 15 amino acids is sufficient to aggregate into short amyloid-like fibrils, whose formation is however strictly dependent on the specific VGGVG repeated sequence. Moreover, in the attempt to elucidate the relationship among aggregation properties, fibers morphology and biocompatibility, 3T3 fibroblasts were grown in the presence of VGGVG-containing elastin-like peptides (ELPs) and analyzed for their ability to proliferate, attach and spread on ELPs-coated surfaces. Data clearly show that amyloid-like fibrils made of (VGGVG)3 are not cytotoxic at least up to the concentration of 100 μg/ml, even after several days of culture, and are a good support for cell attachment and spreading.

Keywords: Amyloid fibrils; Cell spreading; Cell viability; Elastin-like polypeptides; Reactive oxygen species; Supramolecular structure.