TY - JOUR
T1 - Molecular Determinants for Substrate Interactions with the Glycine Transporter GlyT2
AU - Carland, Jane E.
AU - Thomas, Michael
AU - Mostyn, Shannon N.
AU - Subramanian, Nandhitha
AU - O'Mara, Megan L.
AU - Ryan, Renae M.
AU - Vandenberg, Robert J.
N1 - Publisher Copyright:
© 2017 American Chemical Society.
PY - 2018/3/21
Y1 - 2018/3/21
N2 - Transporters in the SLC6 family play key roles in regulating neurotransmission and are the targets for a wide range of therapeutics. Important insights into the transport mechanisms and the specificity of drug interactions of SLC6 transporters have been obtained from the crystal structures of a bacterial homologue of the family, LeuT Aa , and more recently the Drosophila dopamine transporter and the human serotonin transporter. However, there is disputed evidence that the bacterial leucine transporter, LeuT Aa , contains two substrate binding sites that work cooperatively in the mechanism of transport, with the binding of a second substrate being required for the release of the substrate from the primary site. An alternate proposal is that there may be low affinity binding sites that serve to direct the flow of substrates to the primary site. We have used a combination of molecular dynamics simulations of substrate interactions with a homology model of GlyT2, together with radiolabeled amino acid uptake assays and electrophysiological analysis of wild-type and mutant transporters, to provide evidence that substrate selectivity of GlyT2 is determined entirely by the primary substrate binding site and, furthermore, if a secondary site exists then it is a low affinity nonselective amino acid binding site.
AB - Transporters in the SLC6 family play key roles in regulating neurotransmission and are the targets for a wide range of therapeutics. Important insights into the transport mechanisms and the specificity of drug interactions of SLC6 transporters have been obtained from the crystal structures of a bacterial homologue of the family, LeuT Aa , and more recently the Drosophila dopamine transporter and the human serotonin transporter. However, there is disputed evidence that the bacterial leucine transporter, LeuT Aa , contains two substrate binding sites that work cooperatively in the mechanism of transport, with the binding of a second substrate being required for the release of the substrate from the primary site. An alternate proposal is that there may be low affinity binding sites that serve to direct the flow of substrates to the primary site. We have used a combination of molecular dynamics simulations of substrate interactions with a homology model of GlyT2, together with radiolabeled amino acid uptake assays and electrophysiological analysis of wild-type and mutant transporters, to provide evidence that substrate selectivity of GlyT2 is determined entirely by the primary substrate binding site and, furthermore, if a secondary site exists then it is a low affinity nonselective amino acid binding site.
UR - http://www.scopus.com/inward/record.url?scp=85044307156&partnerID=8YFLogxK
U2 - 10.1021/acschemneuro.7b00407
DO - 10.1021/acschemneuro.7b00407
M3 - Article
SN - 1948-7193
VL - 9
SP - 603
EP - 614
JO - ACS Chemical Neuroscience
JF - ACS Chemical Neuroscience
IS - 3
ER -