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Reshaping the Binding Pocket of the Neurotransmitter:Solute Symporter (NSS) Family Transporter SLC6A14 (ATB^0,+) Selectively Reduces Access for Cationic Amino Acids and Derivatives

Lookup NU author(s): Dr Catriona AndersonORCiD, Dr Noel Edwards, Andrew WatsonORCiD, Dr Mike Althaus, Professor David Thwaites

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This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).

Abstract

© 2022 by the authors.SLC6A14 (ATB0,+) is unique among SLC proteins in its ability to transport 18 of the 20 proteinogenic (dipolar and cationic) amino acids and naturally occurring and synthetic analogues (including anti-viral prodrugs and nitric oxide synthase (NOS) inhibitors). SLC6A14 mediates amino acid uptake in multiple cell types where increased expression is associated with pathophysiological conditions including some cancers. Here, we investigated how a key position within the core LeuT-fold structure of SLC6A14 influences substrate specificity. Homology modelling and sequence analysis identified the transmembrane domain 3 residue V128 as equivalent to a position known to influence substrate specificity in distantly related SLC36 and SLC38 amino acid transporters. SLC6A14, with and without V128 mutations, was heterologously expressed and function determined by radiotracer solute uptake and electrophysiological measurement of transporter-associated current. Substituting the amino acid residue occupying the SLC6A14 128 position modified the binding pocket environment and selectively disrupted transport of cationic (but not dipolar) amino acids and related NOS inhibitors. By understanding the molecular basis of amino acid transporter substrate specificity we can improve knowledge of how this multi-functional transporter can be targeted and how the LeuT-fold facilitates such diversity in function among the SLC6 family and other SLC amino acid transporters.

Publication metadata

Author(s): Anderson CMH, Edwards N, Watson AK, Althaus M, Thwaites DT

Publication type: Article

Publication status: Published

Journal: Biomolecules

Year: 2022

Volume: 12

Issue: 10

Print publication date: 01/10/2022

Online publication date: 01/10/2022

Acceptance date: 29/09/2022

Date deposited: 07/11/2022

ISSN (electronic): 2218-273X

Publisher: MDPI

URL: https://doi.org/10.3390/biom12101404

DOI: 10.3390/biom12101404

PubMed id: 36291613

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