Structural Determinants of the Dopamine Transporter Regulation Mediated by G Proteins

J Chem Inf Model. 2020 Jul 27;60(7):3577-3586. doi: 10.1021/acs.jcim.0c00236. Epub 2020 Jun 22.

Abstract

Dopamine clearance in the brain is controlled by the dopamine transporter (DAT), a protein residing in the plasma membrane, which drives reuptake of extracellular dopamine into presynaptic neurons. Studies have revealed that the βγ subunits of heterotrimeric G proteins modulate DAT function through a physical association with the C-terminal region of the transporter. Regulation of neurotransmitter transporters by Gβγ subunits is unprecedented in the literature; therefore, it is interesting to investigate the structural details of this particular protein-protein interaction. Here, we refined the crystal structure of the Drosophila melanogaster DAT (dDAT), modeling de novo the N- and C-terminal domains; subsequently, we used the full-length dDAT structure to generate a comparative model of human DAT (hDAT). Both proteins were assembled with Gβ1γ2 subunits employing protein-protein docking, and subsequent molecular dynamics simulations were run to identify the specific interactions governing the formation of the hDAT:Gβγ and dDAT:Gβγ complexes. A [L/F]R[Q/E]R sequence motif containing the residues R588 in hDAT and R587 in dDAT was found as key to bind the Gβγ subunits through electrostatic interactions with a cluster of negatively charged residues located at the top face of the Gβ subunit. Alterations of DAT function have been associated with multiple devastating neuropathological conditions; therefore, this work represents a step toward better understanding DAT regulation by signaling proteins, allowing us to predict therapeutic target regions.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • Dopamine
  • Dopamine Plasma Membrane Transport Proteins / chemistry*
  • Drosophila Proteins / chemistry*
  • Drosophila melanogaster* / metabolism
  • GTP-Binding Proteins / chemistry*
  • Molecular Dynamics Simulation

Substances

  • DAT protein, Drosophila
  • Dopamine Plasma Membrane Transport Proteins
  • Drosophila Proteins
  • GTP-Binding Proteins
  • Dopamine