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Scientific result | Chemistry

Importance of chemical modifications of proteins for their interactions with nanoparticles


​Two Research Teams from I2BC@Saclay and SPI (LI2D, Marcoule), in collaboration with IRAMIS, highlight the very strong affinity of silica nanoparticles for proteins with RGG motifs (family of binding proteins). RNA), especially when these are methylated. These results are important for the development of safe by design approaches.

Published on 24 May 2018

​Abstract

Understanding the mechanisms involved in the interaction of proteins with inorganic surfaces is of major interest for both basic research and practical applications involving nanotechnology. From the list of cellular proteins with the highest affinity for silica nanoparticles, we highlighted the group of proteins containing arginine–glycine–glycine (RGG) motifs. Biochemical experiments confirmed that RGG motifs interact strongly with the silica surfaces. The affinity of these motifs is further increased when the R residue is asymmetrically, but not symmetrically, dimethylated. Molecular dynamics simulations show that the asymmetrical dimethylation generates an electrostatic asymmetry in the guanidinium group of the R residue, orientating and stabilizing it on the silica surface. The RGG motifs (methylated or not) systematically target the siloxide groups on the silica surface through an ionic interaction, immediately strengthened by hydrogen bonds with proximal silanol and siloxane groups. Given that, in vivo, RGG motifs are often asymmetrically dimethylated by specific cellular methylases, our data add support to the idea that this type of methylation is a key mechanism for cells to regulate the interaction of the RGG proteins with their cellular partners.

Read the French version.

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