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Activity at Aquifex aeolicus sodium-coupled leucine transporter assessed as inhibition of L-[3H]Ala transport at 1 uM

PubChem AID
329206
Primary Citation
Antidepressant binding site in a bacterial homologue of neurotransmitter transporters [PMID: 17687333]
Source
External ID
BioAssay Type
Confirmatory
Tested Substances
Tested Compounds
Version
Status
Live
Dates
  • Deposit:
    2010-05-25
  • Modify:
    2022-08-30
Description
This bioassay record (AID 329206) reports results from the above primary citation. Additional data from the same publication are reported in a total of 5 BioAssay records in PubChem.

1 Description

Title: Antidepressant binding site in a bacterial homologue of neurotransmitter transporters.

Abstract: Sodium-coupled transporters are ubiquitous pumps that harness pre-existing sodium gradients to catalyse the thermodynamically unfavourable uptake of essential nutrients, neurotransmitters and inorganic ions across the lipid bilayer. Dysfunction of these integral membrane proteins has been implicated in glucose/galactose malabsorption, congenital hypothyroidism, Bartter's syndrome, epilepsy, depression, autism and obsessive-compulsive disorder. Sodium-coupled transporters are blocked by a number of therapeutically important compounds, including diuretics, anticonvulsants and antidepressants, many of which have also become indispensable tools in biochemical experiments designed to probe antagonist binding sites and to elucidate transport mechanisms. Steady-state kinetic data have revealed that both competitive and noncompetitive modes of inhibition exist. Antagonist dissociation experiments on the serotonin transporter (SERT) have also unveiled the existence of a low-affinity allosteric site that slows the dissociation of inhibitors from a separate high-affinity site. Despite these strides, atomic-level insights into inhibitor action have remained elusive. Here we screen a panel of molecules for their ability to inhibit LeuT, a prokaryotic homologue of mammalian neurotransmitter sodium symporters, and show that the tricyclic antidepressant (TCA) clomipramine noncompetitively inhibits substrate uptake. Cocrystal structures show that clomipramine, along with two other TCAs, binds in an extracellular-facing vestibule about 11 A above the substrate and two sodium ions, apparently stabilizing the extracellular gate in a closed conformation. Off-rate assays establish that clomipramine reduces the rate at which leucine dissociates from LeuT and reinforce our contention that this TCA inhibits LeuT by slowing substrate release. Our results represent a molecular view into noncompetitive inhibition of a sodium-coupled transporter and define principles for the rational design of new inhibitors.

2 Comment

Compounds with activity <= 10uM or explicitly reported as active by ChEMBL are flagged as active in this PubChem assay presentation.

Journal: Nature

Year: 2007

Volume: 448

Issue: 7156

First Page: 952

Last Page: 956

DOI: 10.1038/nature06038

3 Result Definitions

4 Data Table

6 Identity

6.1 BioAssay Name

Activity at Aquifex aeolicus sodium-coupled leucine transporter assessed as inhibition of L-[3H]Ala transport at 1 uM

6.2 Source

6.3 External ID

6.4 Project Category

Literature, Extracted

6.5 BioAssay Type

Confirmatory

6.6 Deposit Date

2010-05-25

6.7 Modify Date

Version 1.1
Version 2.1
Version 3.1
Version 3.2
Version 3.3
Version 4.1
Version 4.2
Version 4.3
Version 5.1
Version 6.1
Version 7.1
Version 8.1
Version 8.2
Version 9.1
Version 10.1
Version 10.2
2022-08-30 (currently shown)

6.8 Status

Live

7 Same-Publication BioAssays

8 BioAssay Annotations

Assay Type
Binding
Assay Organism

9 Information Sources

  1. PubChem
  2. ChEMBL
    LICENSE
    Access to the web interface of ChEMBL is made under the EBI's Terms of Use (http://www.ebi.ac.uk/Information/termsofuse.html). The ChEMBL data is made available on a Creative Commons Attribution-Share Alike 3.0 Unported License (http://creativecommons.org/licenses/by-sa/3.0/).
    http://www.ebi.ac.uk/Information/termsofuse.html
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