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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.

The voltage-dependent anion channel (VDAC) is a crucial mitochondrial protein that facilitates ion and metabolite exchange between mitochondria and the cytosol. Initially characterized over three decades ago, the structure of VDAC-1 was resolved in 2008, revealing a novel β-barrel protein architecture. This study presents the first room-temperature crystal structure of mouse VDAC-1 (mVDAC-1), which is a significant step toward understanding the channel’s gating mechanism. The new structure, obtained at a 3.3 Å resolution, demonstrates notable differences from the previously determined cryogenic structure, particularly in the loop regions, which may be critical for the transition between the ‘open’ and ‘closed’ states of VDAC-1. Comparative analysis of the root-mean-square deviation (R.M.S.D.) and B-factors between the cryogenic and room-temperature structures suggests that these conformational differences, although subtle, are important for VDAC’s functional transitions. The application of electric field-stimulated X-ray crystallography (EF-X) is proposed as a future direction to resolve the ‘closed’ state of VDAC-1 by inducing voltage-driven conformational changes in order to elucidate the dynamic gating mechanism of VDAC-1. Our findings have profound implications for understanding the molecular basis of VDAC’s role in mitochondrial function and its regulation under physiological conditions.