Membrane potential accelerates sugar uptake by stabilizing the outward facing conformation of the Na/glucose symporter vSGLT

Farha Khan; Matthias Elgeti; Samuel Grandfield; Aviv Paz; Fiona B Naughton; Frank V Marcoline; Thorsten Althoff; Natalia Ermolova; Ernest M Wright; Wayne L Hubbell; Michael Grabe; Jeff Abramson

doi:10.1038/s41467-023-43119-z

Membrane potential accelerates sugar uptake by stabilizing the outward facing conformation of the Na/glucose symporter vSGLT

Nat Commun. 2023 Nov 18;14(1):7511. doi: 10.1038/s41467-023-43119-z.

Authors

Farha Khan^#^{1

2}, Matthias Elgeti^#^{3

4}, Samuel Grandfield^{1

5}, Aviv Paz^{1

6}, Fiona B Naughton⁷, Frank V Marcoline⁷, Thorsten Althoff¹, Natalia Ermolova¹, Ernest M Wright¹, Wayne L Hubbell^{8

9}, Michael Grabe¹⁰, Jeff Abramson¹¹

Affiliations

¹ Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, 90095, USA.
² Department of Structural Biology, Van Andel Institute, Grand Rapids, MI, 49503, USA.
³ Stein Eye Institute, University of California, Los Angeles, Los Angeles, CA, 90095, USA. melgeti@ucla.edu.
⁴ Institute for Drug Discovery, Leipzig University Medical School, Leipzig, Germany. melgeti@ucla.edu.
⁵ Renaissance School of Medicine at Stony Brook University, Stony Brook, NY, 11794, USA.
⁶ Hauptman-Woodward Medical Research Institute, 700 Ellicott Street, Buffalo, NY, 14203, USA.
⁷ Department of Pharmaceutical Chemistry, Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA, 94158, USA.
⁸ Stein Eye Institute, University of California, Los Angeles, Los Angeles, CA, 90095, USA.
⁹ Department of Chemistry and Biochemistry, University of California, Los Angeles, Los Angeles, CA, 90095, USA.
¹⁰ Department of Pharmaceutical Chemistry, Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA, 94158, USA. michael.grabe@ucsf.edu.
¹¹ Department of Physiology, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, CA, 90095, USA. jabramson@mednet.ucla.edu.

^# Contributed equally.

Abstract

Sodium-dependent glucose transporters (SGLTs) couple a downhill Na⁺ ion gradient to actively transport sugars. Here, we investigate the impact of the membrane potential on vSGLT structure and function using sugar uptake assays, double electron-electron resonance (DEER), electrostatic calculations, and kinetic modeling. Negative membrane potentials, as present in all cell types, shift the conformational equilibrium of vSGLT towards an outward-facing conformation, leading to increased sugar transport rates. Electrostatic calculations identify gating charge residues responsible for this conformational shift that when mutated reduce galactose transport and eliminate the response of vSGLT to potential. Based on these findings, we propose a comprehensive framework for sugar transport via vSGLT, where the cellular membrane potential facilitates resetting of the transporter after cargo release. This framework holds significance not only for SGLTs but also for other transporters and channels.

Publication types

Research Support, N.I.H., Extramural

MeSH terms

Electron Spin Resonance Spectroscopy
Galactose / metabolism
Glucose
Membrane Potentials
Protein Conformation
Sodium / metabolism
Sodium-Glucose Transport Proteins / chemistry
Sodium-Glucose Transport Proteins / genetics
Sodium-Glucose Transport Proteins / metabolism
Sugars
Symporters* / metabolism

Substances

Symporters
Sugars
Glucose
Galactose
Sodium-Glucose Transport Proteins
Sodium

Abstract

Publication types

MeSH terms

Substances

Grants and funding