Neurotransmitter:Na(+) symporters (NSS) remove neurotransmitters from the synapse in a reuptake process that is driven by the naturally occuring Na(+) gradient. Drugs that interfere with this reuptake mechanism, such as cocaine and antidepressants, profoundly influence behaviour and mood. To probe the nature of the conformational changes that are associated with substrate binding and transport, we have developed a single-molecule fluorescence imaging assay and combined it with functional and computational studies of the prokaryotic NSS homologue Leucine Transporter (LeuT).
Shown here is a morph of the conformational movements of LeuT as predicted by crystallographic studies. Using this as a framework for eneineering fluorophore labeling sites (spheres), we have investigated the dynamics of LeuT in response to natural ligands and drugs. We show molecular details of the modulation of intracellular gating of LeuT by substrates and inhibitors. These studies have led to a detalied allosteric mechanism that couples ion and substate binding to aminoacid transport.
Substrate-Modulated Gating Dynamics in a Na(+)-coupled Neurotransmitter Transporter Homologue. Zhao Y, Terry DS, Shi L, Quick M, Weinstein H, Blanchard SC, Javitch JA. NATURE (2011) : Vol.474(7349):109-113. PMID: 21516104.
Single-Molecule Dynamics of Gating in a Neurotransmitter Transporter Homologue. Zhao YZ, Terry D, Shi L, Weinstein H, Blanchard SC, Javitch JA; NATURE (2010) Vol. 465(7295):188-93. PMID: 20463731.