The propagation of mammalian prions made up of proteins devoid of nucleic acids is far from having revealed all its secrets. For the first time, INRA researchers show that an elementary unit of a trimer of proteins is necessary and sufficient for the replication of these pathogens. These original results are published on September 7 in the journal Plos Pathogens.

Discovery on Prion Propagation

Responsible for diseases affecting particularly the human and livestock, prions are infectious protein particles, devoid of material genetics. The protein prion comes in two forms, aa normal form associated with biological functions, and an infectious ill-folded form capable of recruiting other proteins by transmitting this aberrant conformation. The prion protein, in its infectious form, forms assemblages of various sizes.

Deciphering the modalities of replication and propagation of prions is a challenge that has been pursued by INRA researchers. They have just reached a decisive stage, revealing the existence within prion assemblies of an elementary structural determinant, which contains the necessary and sufficient information for the replication of these unconventional pathogens.

Exploring the architecture of prion assemblies, scientists have shown that these are composed of elementary units, made up of a trimer of proteins. Common to several strains, these elementary units constitute a generic characteristic of prions and contain the necessary and sufficient information for their replication. These elementary bricks are extremely resistant to the biochemical agents usually capable of destroying the protein acetous cellular compounds. Moreover, when two elementary units are linked, they become pathogenic. The bonds which unite these two elementary units, of the hydrophobic type, are however very fragile.

The variability of this elementary brick, whether it is the structure of the trimer or other, is responsible for the diversity of prion strains and their ability to infect different animal species. In their experiments, INRA scientists suggest that under physiological conditions prion assemblies and elementary units are in equilibrium such that elementary units can be released when they are in small quantities on the contrary captured when they are in excess. The existence of this equilibrium thus enables the elementary unit to participate actively in the propagation of the prion in the cells or in the tissues against a background of depolymerization of the prion assemblies.

Necessary and sufficient for the propagation of the prion, within an infected tissue, this brick could prove to be a therapeutic target of interest. Opening the door to possible prospects against the prion diseases which to this day are fatal to man and animals. In the short term, the characterization of its size and adsorption properties should enable healthcare companies to develop retention and decontamination techniques that are better adapted and more efficient.

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The propagation of mammalian prions made up of proteins devoid of nucleic acids is far from having revealed all its secrets. For the first time, INRA researchers show that an elementary unit of a trimer of proteins is necessary and sufficient for the replication of these pathogens. These original...