Solute carrier 11 cation symport requires distinct residues in transmembrane helices 1 and 6

Courville, Pascal; Urbankova, Eva; Rensing, Christopher; Chaloupka, Roman; Quick, Matthias et Cellier, Mathieu ORCID: https://orcid.org/0000-0002-6084-434X (2008). Solute carrier 11 cation symport requires distinct residues in transmembrane helices 1 and 6 Journal of Biological Chemistry , vol. 283 , nº 15. pp. 9651-9658. DOI: 10.1074/jbc.M709906200.

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Résumé

Ubiquitous solute carriers 11 (SLC11) contribute to metal-ion homeostasis by importing Me2+ and H+ into the cytoplasm. To identify residues mediating cation symport, Escherichia coli proton-dependent manganese transporter (MntH) was mutated at five SLC11-specific transmembrane (TM) sites; each mutant activity was compared with wild-type MntH, and the biochemical results were tested by homology threading. Cd2+ and H+ uptake kinetics were analyzed in whole cells as a function of pH and temperature, and right-side out membrane vesicles were used to detail energy requirements and to probe site accessibility by Cys replacement and thiol modification. This approach revealed that TM segment 1 (TMS1) residue Asp(34) couples H+ and Me2+ symport and contributes to MntH forward transport electrogenicity, whereas the TMS6 His(211) residue mediates pH-dependent Me2+ uptake; MntH Asn(37), Asn(250), and Asn(401) in TMS1, TMS7, and TMS11 participate in transporter cycling and/or helix packing interactions. These biochemical results fit the LeuT/SLC6 structural fold, which suggests that conserved peptide motifs Asp(34)-Pro-Gly (TMS1) and Met-Pro-His(211) (TMS6) form antiparallel "TM helix/extended peptide" boundaries, lining a "pore" cavity and enabling H+-dependent Me2+ import.

Type de document:	Article
Mots-clés libres:	-
Centre:	Centre INRS-Institut Armand Frappier
Date de dépôt:	22 juill. 2024 19:39
Dernière modification:	22 juill. 2024 19:39
URI:	https://espace.inrs.ca/id/eprint/14522

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