CONICET | Buscador de Institutos y Recursos Humanos

For decades, it has been accepted that proteins contain in their sequence all the necessary information to reach the native state, but the way this information is coded remains elusive. Examination of the thioredoxin structures (TRX) led us to pay particular attention to the hydrophobic cluster involving the C-terminal helix. This region comprises both alpha and beta segments that should organize appropriately to form a hydrophobic concave surface onto which the amphipatic C-terminal helix is tightly docked. Most likely, correct packing at this crucial region will consolidate the overall fold of the protein. Our efforts were then directed toward rationally excising the polypeptide chain of TRX so as to isolate the C-terminal helix from the remainder of the protein. Is successful, this approach would provide a means of dissecting the interaction network to evaluate its importance for determining and stabilizing the final fold. In this context, we started de study of the conformational information contained in a peptide through complementation between the fragments TRX1-93 and TRX94-108. The vast experimental evidence (CD, SEC-FPLC, fluorescence, etc) obtained by our group with this system allows us to undoubtedly assess that none of the fragments is stabilized in the native conformation except when they are in complementation. The important feature of this system, with respect to other TRX complementing systems, is that permits to explore the informational content of a more restricted fraction of the TRX structure. Additionally, we run molecular dynamics simulations of the restricted TRX94-108 peptide, which suggested that the helical native conformation is, at least, a local minimum in its energetic landscape. In conclusion, we propose the use of this model to study the possibility of disaggregating the conformational information contained in the TRX94-108 fragment, distinguishing the principal components determining the TRX folding stabilization