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Mechanobiology

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

AUTHORS

Campbell NGNicholas G , Shekar AAparna , Aguilar JIJenny I , Peng DDungeng , Navratna VVikas , Yang DDongxue , Morley ANAlexander N , Duran AMAmanda M , Galli GGreta , O'Grady BBrian , Ramachandran RRamnarayan , Sutcliffe JSJames S , Sitte HHHarald H , Erreger KKevin , Meiler JJens , Stockner TThomas , Bellan LMLeon M , Matthies HJGHeinrich J G , Gouaux EEric , Mchaourab HSHassane S , Galli AAurelio . Proceedings of the National Academy of Sciences of the United States of America. 2019 2 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.