Structural and physiological aspects of the interaction of proteins with nanostructured materials

Introduction Nanoparticles (NP) are versatile materials that can be prepared and engineered with distinctive composition, size, and surface chemistry. This enables to develop novel and exciting approaches to studying fundamental biological issues at the molecular, cellular, and tissue level. Methods Bacterial cells were covalently conjugated to magnetic NP, and proteins in the captured fragments were subsequently identified by MS approaches. Internalization by human monocytes of covalent and non-covalent fluorescent adducts of various NP and beta-lactoglobulin (BLG, a food allergen) was addressed by flow cytometry, and by confocal and TEM microscopy. Polystyrene NPs were used in refolding studies of metal-containing proteins and for interface denaturation studies. Results The magneto-separation of cell envelope fragments and the subsequent identification of the captured and neighboring proteins improved the sensitivity and specificity of traditional approaches and appeared well suited for envelope studies in pathogenic bacteria. Covalent and non covalent BLG-NP assemblies showed their potential in elucidating the uptake pathway of allergenic proteins. The non-covalent interaction of hydrophobic NP and various proteins provided hints as for interface denaturation events, which may be exploited to increase refolding yields in the case of metal-containing proteins. These latter results suggest a possible use of hydrophobic NPs as “biomimetic chaperones” in biotechnological refolding of cofactor-containing proteins, and underscore the possible relevance of NP-protein interactions in unfolding-related pathologies and intolerances. Conclusions NP has demonstrated to be powerful tools for studying some interlocked fundamental events, such as: a) the molecular recognition issues at the cell surface; b) the uptake and cellular fate of bioactive proteins; and c) the loss/gain of function in proteins as a result of their interactions with nano-sized systems. References 1. Miriani et al., 2014, Proteins, 82, 1272-1282. 2. Miriani et al., 2014, Proteins, 82, 3154–3162. 3. Vecchietti et al., 2012, PLoS ONE, 7, e51062.