Structural basis of ion - substrate coupling in the Na + -dependent dicarboxylate transporter VcINDY.

Autor: Sauer DB; Department of Cell Biology, New York University School of Medicine, New York, NY, 10016, USA.; Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY, 10016, USA.; Centre for Medicines Discovery, Nuffield Department of Medicine, University of Oxford, Oxford, UK., Marden JJ; Department of Cell Biology, New York University School of Medicine, New York, NY, 10016, USA.; Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY, 10016, USA., Sudar JC; Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY, 10016, USA., Song J; Department of Cell Biology, New York University School of Medicine, New York, NY, 10016, USA.; Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY, 10016, USA., Mulligan C; School of Biosciences, University of Kent, Canterbury, Kent, UK. c.mulligan@kent.ac.uk., Wang DN; Department of Cell Biology, New York University School of Medicine, New York, NY, 10016, USA. da-neng.wang@med.nyu.edu.; Skirball Institute of Biomolecular Medicine, New York University School of Medicine, New York, NY, 10016, USA. da-neng.wang@med.nyu.edu.
Jazyk: angličtina
Zdroj: Nature communications [Nat Commun] 2022 May 12; Vol. 13 (1), pp. 2644. Date of Electronic Publication: 2022 May 12.
DOI: 10.1038/s41467-022-30406-4
Abstrakt: The Na + -dependent dicarboxylate transporter from Vibrio cholerae (VcINDY) is a prototype for the divalent anion sodium symporter (DASS) family. While the utilization of an electrochemical Na + gradient to power substrate transport is well established for VcINDY, the structural basis of this coupling between sodium and substrate binding is not currently understood. Here, using a combination of cryo-EM structure determination, succinate binding and site-directed cysteine alkylation assays, we demonstrate that the VcINDY protein couples sodium- and substrate-binding via a previously unseen cooperative mechanism by conformational selection. In the absence of sodium, substrate binding is abolished, with the succinate binding regions exhibiting increased flexibility, including HP in b, TM10b and the substrate clamshell motifs. Upon sodium binding, these regions become structurally ordered and create a proper binding site for the substrate. Taken together, these results provide strong evidence that VcINDY's conformational selection mechanism is a result of the sodium-dependent formation of the substrate binding site.
(© 2022. The Author(s).)
Databáze: MEDLINE
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