Structural, functional, and behavioral insights of dopamine dysfunction revealed by a deletion in

Authors

Campbell NG Nicholas G , Shekar A Aparna , Aguilar JI Jenny I , Peng D Dungeng , Navratna V Vikas , Yang D Dongxue , Morley AN Alexander N , Duran AM Amanda M , Galli G Greta , O'Grady B Brian , Ramachandran R Ramnarayan , Sutcliffe JS James S , Sitte HH Harald H , Erreger K Kevin , Meiler J Jens , Stockner T Thomas , Bellan LM Leon M , Matthies HJG Heinrich J G , Gouaux E Eric , Mchaourab HS Hassane S , Galli A Aurelio .
Proceedings of the National Academy of Sciences of the United States of America. 2019 02 12; 116(9).
3853-3862

Abstract

The human dopamine (DA) transporter (hDAT) mediates clearance of DA. Genetic variants in hDAT have been associated with DA dysfunction, a complication associated with several brain disorders, including autism spectrum disorder (ASD). Here, we investigated the structural and behavioral bases of an ASD-associated in-frame deletion in hDAT at N336 (∆N336). We uncovered that the deletion promoted a previously unobserved conformation of the intracellular gate of the transporter, likely representing the rate-limiting step of the transport process. It is defined by a “half-open and inward-facing” state (HOIF) of the intracellular gate that is stabilized by a network of interactions conserved phylogenetically, as we demonstrated in hDAT by Rosetta molecular modeling and fine-grained simulations, as well as in its bacterial homolog leucine transporter by electron paramagnetic resonance analysis and X-ray crystallography. The stabilization of the HOIF state is associated both with DA dysfunctions demonstrated in isolated brains of expressing hDAT ∆N336 and with abnormal behaviors observed at high-time resolution. These flies display increased fear, impaired social interactions, and locomotion traits we associate with DA dysfunction and the HOIF state. Together, our results describe how a genetic variation causes DA dysfunction and abnormal behaviors by stabilizing a HOIF state of the transporter.