PROTEINARCHEOLOGY · protein archeology : reconstructed ancestors for protein engineering and crystallography

Advances in molecular evolution led to the novel concept of ancestral resurrections, or reconstructions. These allow the exploration of the mechanisms by which new protein families diverged. Reconstructed ancestors are also inherently more prone to functional divergence, and exhibit higher thermal stability, making them more tolerant to mutations, and potentially more evolvable. However, to date, very few ancestors have been resurrected, and the experimental methodologies are still lacking. I aim to develop and apply ancestor resurrections techniques. My first model will be the serum paraoxonase (PON) family. Widespread in vertebrates and bacteria, PONs’ physiological roles span from preventing atherosclerosis to bacterial quorum quenching. Going backwards into PON’s history, we will reconstruct PON’s last common vertebrate ancestor, and acquire insights regarding the divergence of various PON families. The ancestor’s properties (enzymatic and structural) may inform us, for example, how vertebrate PONs emerged from bacterial PONs that acted in quorum quenching. The ancestor, stable and soluble, would also provide an ideal starting point for directed evolution and structural determination. Once the methodologies are developed, other proteins will be subjected to a similar study with the aim of turning ancestor resurrections into a general and powerful tool for protein engineering and structural determination.