Quantitative Assessment of the Energetics of Dopamine Translocation by Human Dopamine Transporter

Abstract

<p class="first" id="P1">Computational evaluation of the energetics of substrate binding, transport, and release events of neurotransmitter transporters at the molecular level is a challenge, as the structural transitions of these membrane proteins involve coupled global and local changes that span time scales of several orders of magnitude, from nanoseconds to seconds. Here, we provide a quantitative assessment of the energetics of dopamine (DA) translocation through the human DA transporter (hDAT), using a combination of molecular modeling, simulation, and analysis tools. DA-binding and -unbinding events, which generally involve local configurational changes, are evaluated using free-energy perturbation or adaptive biasing force methods. The global transitions between the outward-facing state and the inward-facing state, on the other hand, require a dual-boost accelerated molecular dynamics simulation. We present results on DA-binding/unbinding energetics under different conditions, as well as the conformational energy landscape of hDAT in both DA-bound and -unbound states. The study provides a tractable method of approach for quantitative evaluation of substrate-binding energetics and efficient estimation of conformational energy landscape, in general. </p><p id="P3"> <div class="figure-container so-text-align-c"> <img alt="" class="figure" src="/document_file/e1a7e96c-56f0-491b-ab52-aedcd2195419/PubMedCentral/image/nihms970710u1.jpg"/> </div> </p>