Structure of self-assembling protein nanoparticles designed for clinical applications

JULIETA M. SANCHEZ; LAURA SÁNCHEZ-GARCIA; MIREIA PESARRODONA; NAROA SERNA; ALEJANDRO SÁNCHEZ-CHARDI; UGUTZ UNZUETA ,; RAMÓN MANGUES; ESTHER VÁZQUEZ; ANTONIO VILLAVERDE

Barcelona

Simposio; International Symposium of Suprabiomolecular systems; 2019

Université de Bordeaux y University of Southamptom

Protein-based nanoparticles are rapidly gaining interest in materials sciences and nanomedicine because of their intrinsic biocompatibility and full biodegradability.Through protein engineering concepts we designed a targeting ligand, a functionalizing domains in a single polypeptide chain (Figure 1), as the building block (BB) of protein-only nanoparticles.Oligomerizationis achieved under controlled chemical conditions into regular nanoparticles ranging around 12 nm. Two functionalcore-proteins were used, namely GFP anddiphtheria toxin (Ditox), the former as a molecular marker, the later as an effectively toxic moiety that reduces tumoral cells viability. The cationic peptide T22 is the ligand of the CXCR4 receptor over-expressed in metastatic colorectal cancer cells. The oligomerization takes place when this cationic peptide cross-interactswith the his-tag appliedfor the protein purification.In the oligomeric form not only the renal clearance is prevented but also T22-mediated tumoral cell internalisation is dramatically favoured1.In this work we study the structural bases on non-amylogenic oligomerization by means of spectrofluorimetry and spectropolarimetry.We demonstrate that the novel conformation acquired by the proteins, as BB of these supramolecular assemblies, shows different extents of compactness and results in a beta structure enrichment beyond the initial secondary structure (Figure 2)that improve the structural stability. This structural profiling adds clues for the further design of self-assembling protein nanoparticles that, like DITOX nanoparticle, base both architecture and therapeutic activity on the conformation of the assembled protein.1-Xu, Z.U. et al. Formulating tumor-homing peptides as regular nanoparticles enhances receptor-mediated cell penetrability. Materials Lett 2015,154, 140-143.