Substrate-Induced Conformational Dynamics of the Dopamine Transporter

Abstract

The dopamine transporter is a member of the neurotransmitter:sodium symporters (NSSs), which are responsible for termination of neurotransmission through Na+-driven reuptake of neurotransmitter from the extracellular space. The coordinated conformational rearrangements related to the transport mechanism have so far been poorly understood. Here we have probed the global Na+- and dopamine-induced conformational dynamics of the wild-type Drosophila melanogaster dopamine transporter using hydrogen-deuterium exchange mass spectrometry. We identify Na+- and dopamine-induced changes in specific regions of the transporter, suggesting their involvement in protein conformational transitions. Furthermore, we detect novel ligand-dependent slow cooperative fluctuations of helical stretches in several domains of the transporter, which could be a novel molecular mechanism that assists in the transporter function. Our results provide a framework for understanding the molecular mechanism underlying the function of NSSs by revealing the first detailed insight into the state-dependent conformational changes associated with the alternating access model of a eukaryotic NSS.