In order to gain insight of the mechanisms behind these events, Rafael Giraldo's laboratory at the National Center for Biotechnology (CNB-CSIC), have developed a model to study the dynamics and transmission mechanisms of prions. Using synthetic biology techniques and the bacterial protein RepA–WH1, they had modified the conformational dynamics of the protein using various types of ligands such as DNA, phospholipids, or nanoparticles to induce its assembly into amyloid fibers. This model allows the study of protein toxicity in Escherichia coli, in which the original protein is harmless. The synthetic prion spreads in the form of two different structural variants during cell division. The most cytotoxic lineage produces pores in the bacterial inner membrane making it unable to detoxify free radicals that are generated as a result of membrane damage, resulting in bacterial death.
The journal mBio has just published their new work, where they have studied the transmission of the bacterial synthetic prion RepA-WH1 in cultured human and mice cell lines. Using several approaches, they have shown that prion propagation is only possible if the target cells previously contain the RepA-WH1 protein itself. In this case, the amyloid aggregates get inside the receptor cells, where they reproduce the structure on the soluble RepA-WH1 molecules, causing the formation of new intracellular amyloid aggregates. Giraldo highlights “the aggregated protein especially affects the functionality of mitochondria, the organelles responsible for cellular respiration, following an analogous mechanisms to those we had previously described in E. coli. This suggests that the mechanisms of transmission and amyloid cytotoxicity are universal and can be reconstructed by Synthetic Biology”. In addition, Giraldo remarks that one of the advantages of working with this synthetic prion is its biosecurity, since it does not spread in human or animal cells that do not naturally express RepA-WH1, allowing to understand their transmission dynamics without risks.