How dopamine transporter interacts with dopamine: insights from molecular modeling and simulation.
By performing homology modeling, molecular docking, and molecular dynamics simulations, we have developed three-dimensional (3D) structural models of both dopamine transporter and dopamine transporter-dopamine complex in the environment of lipid bilayer and solvent water. According to the simulated structure of dopamine transporter-dopamine complex, dopamine was orientated in a hydrophobic pocket at the midpoint of the membrane. The modeled 3D structures provide some detailed structural and mechanistic insights concerning how dopamine transporter (DAT) interacts with dopamine at atomic level, extending our mechanistic understanding of the dopamine reuptake with the help of Na(+) ions. The general features of the modeled 3D structures are consistent with available experimental data. Based on the modeled structures, our calculated binding free energy (DeltaG(bind) = -6.4 kcal/mol) for dopamine binding with DAT is also reasonably close to the experimentally derived DeltaG(bind) value of -7.4 kcal/mol. Finally, a possible dopamine-entry pathway, which involves formation and breaking of the salt bridge between side chains of Arg(85) and Asp(476), is proposed based on the results obtained from the modeling and molecular dynamics simulation. The new structural and mechanistic insights obtained from this computational study are expected to stimulate future, further biochemical and pharmacological studies on the detailed structures and mechanisms of DAT and other homologous transporters.
Huang
Xiaoqin
X
Department of Pharmaceutical Sciences, College of Pharmacy, University of Kentucky, Lexington, Kentucky, USA.
Zhan
Chang-Guo
CG
D000595:Amino Acid Sequence; D003198:Computer Simulation; D030562:Databases, Protein; D004298:Dopamine / Q000737:chemistry / Q000378:metabolism*; D050483:Dopamine Plasma Membrane Transport Proteins / Q000378:metabolism*; D006801:Humans; D007477:Ions; D008958:Models, Molecular; D008968:Molecular Conformation; D008969:Molecular Sequence Data; D011485:Protein Binding; D011487:Protein Conformation; D017386:Sequence Homology, Amino Acid; D012964:Sodium / Q000737:chemistry; D012984:Software; D013816:Thermodynamics; D013997:Time Factors
D050483:Dopamine Plasma Membrane Transport Proteins; D007477:Ions; D012964:Sodium; D004298:Dopamine
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