Peroxiredoxin promotes longevity and HO-resistance in yeast through redox-modulation of protein kinase A.

Peroxiredoxins are HO scavenging enzymes that also carry out HO signaling and chaperone functions. In yeast, the major cytosolic peroxiredoxin, Tsa1 is required for both promoting resistance to HO and extending lifespan upon caloric restriction. We show here that Tsa1 effects both these functions not by scavenging HO, but by repressing the nutrient signaling Ras-cAMP-PKA pathway at the level of the protein kinase A (PKA) enzyme.

Importance of Post-translational Modifications in the Interaction of Proteins with Mineral Surfaces: The Case of Arginine Methylation and Silica surfaces.

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.

RNA-binding proteins are a major target of silica nanoparticles in cell extracts.

Upon contact with biological fluids, nanoparticles (NPs) are readily coated by cellular compounds, particularly proteins, which are determining factors for the localization and toxicity of NPs in the organism. Here, we improved a methodological approach to identify proteins that adsorb on silica NPs with high affinity. Using large-scale proteomics and mixtures of soluble proteins prepared either from yeast cells or from alveolar human cells, we observed that proteins with large unstructured region(s) are more prone to bind on silica NPs.

Structural determinants for protein adsorption/non-adsorption to silica surface.

The understanding of the mechanisms involved in the interaction of proteins with inorganic surfaces is of major interest in both fundamental research and applications such as nanotechnology. However, despite intense research, the mechanisms and the structural determinants of protein/surface interactions are still unclear. We developed a strategy consisting in identifying, in a mixture of hundreds of soluble proteins, those proteins that are adsorbed on the surface and those that are not.