The neurotransmitter transporters (NSSs) are membrane proteins located to the presynaptic terminal on neurons. They control neuronal communication by rapid reuptake of neurotransmitters. The rewarding effects of cocaine is due to its inhibition of the NNS for dopamine (DAT). There is no medical treatment for cocaine addiction. The atypical DAT inhibitors (ADIs) do also inhibit DAT, but they are not rewarding. Rather, they antagonize the effect of cocaine, making ADIs possible cocaine antidotes. The mechanism behind this is largely unknown, and the further exploration of this conundrum has been hampered by experimental limitations in the purification of functional DAT. We are the first to report the purification of functional DAT wild type.
The purpose of this project is to elucidate the fundamental differences in binding dynamics between cocaine and ADIs with advanced pharmacological technologies and state-of-the-art biophysical methods. This could include structural determination. We will find the molecular determinants that constitute the distinct pharmacological signatures of ADIs and cocaine. Our profound expertise in investigating protein conformational dynamics allows us to elucidate the specific DAT conformations induced by the two drug classes. Specifically, we will measure distances between specific DAT domains and how they are influenced by ligands. We wish to map the global structural dynamics induced by ligand binding using e.g. FRET-based methods and unnatural amino acids. Together, they could reveal a conformational ‘fingerprint’ for each drug class enabling a prediction for categorizing novel compounds.
We expect that these findings will provide novel information on complex conformational dynamics on a hitherto unpreceded level of detail and provide fundamental insight in why some DAT inhibitors are stimulants while others are not. This will contribute significantly to the development of a drug against cocaine abuse.