Role of Histidine 547 of Human Dopamine Transporter in Molecular Interaction with HIV-1 Tat and Dopamine Uptake

According to the 2013 report of World Health Organization (WHO), about 35.3 million people in the world live with the acquired immune deficiency syndrome (AIDS) disease caused by human immunodeficiency virus (HIV)1, and about 70% of HIV-infected individuals suffer from HIV-associated neurocognitive disorders (HAND)2,3,4,5. Within the genes of HIV virus, the transactivator of transcription (Tat) gene plays a crucial role in regulation of proteins that control how the HIV virus infects cells2,6,7,8. It has been known that HIV-1 Tat, detected in the brain and the sera of HIV-1 patients9,10,11, plays an important role in HAND by disrupting neurotransmission12 including dopamine uptake by human dopamine transporter (hDAT). Presynaptic hDAT activity is strikingly reduced in HIV-1 patients, particularly those with cocaine abuse13,14. Recently reported computational and experimental studies15,16,17 examined how HIV-1 Tat interacts with hDAT at molecule level, demonstrating that HIV-1 Tat directly binds to hDAT and that amino-acid residues Y88, K92, and Y470 of hDAT are involved in the hDAT-Tat binding. The K92M, Y470H, and Y470A mutations all significantly attenuated Tat-induced inhibition of dopamine uptake. Meanwhile, these mutations also decreased the Vmax of hDAT for dopamine uptake15,16,17. Here we demonstrate that H547 is also involved in the hDAT-Tat binding, and that the H547A mutation can not only considerably attenuate Tat-induced inhibition of dopamine uptake, but also significantly increase the Vmax of hDAT for dopamine uptake. The unusual H547A mutation on hDAT was proposed based on computational modeling of the detailed three-dimensional (3D) structures, followed by in vitro pharmacological testing. The finding of such an unusual hDAT mutant capable of increasing the Vmax of hDAT for dopamine uptake while effectively attenuating Tat-induced inhibition of dopamine uptake may provide an exciting knowledge basis for development of novel concepts for therapeutic treatment of the HAND.