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Updated: Jan 13, 2026
11:19
Site Directed Spin Labeling and EPR Spectroscopic Studies of Pentameric Ligand-Gated Ion Channels
Published on: July 4, 2016
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Elevator mechanism dynamics in a sodium-coupled dicarboxylate transporter
Colin D Kinz-Thompson1, Maria Louisa Lopez-Redondo2, Christopher Mulligan3
1Department of Chemistry, Columbia University, New York, NY 10027.
Summary
VcINDY, a transporter from Vibrio cholerae, uses fast, elevator-like movements to move dicarboxylates across membranes. Its two parts work independently, suggesting a unique mechanism for efficient nutrient uptake.
Area of Science:
- Biochemistry
- Molecular Biology
- Membrane Transport
Background:
- VcINDY (Vibrio cholerae sodium-dependent dicarboxylate transporter) facilitates C4-carboxylate uptake.
- The precise mechanism of VcINDY substrate translocation and energy efficiency remains elusive.
Purpose of the Study:
- To elucidate the dynamic molecular mechanism of VcINDY-mediated substrate transport.
- To investigate the conformational changes and kinetics of VcINDY during transport.
Main Methods:
- Single-molecule fluorescence resonance energy transfer (smFRET) experiments.
- Observation of individual VcINDY mechanistic steps during lipid bilayer translocation.
- Testing predictions of transport cycle mechanistic models.
Main Results:
- Direct, dynamic evidence of stochastic, elevator-type conformational motions enabling substrate translocation.
- VcINDY motion dynamics are ~10x faster than substrate turnover, indicating multiple translocation rounds per cycle.
- VcINDY protomers exhibit noncooperative motions, suggesting independent transport reactions.
Conclusions:
- VcINDY utilizes rapid, independent conformational changes for efficient dicarboxylate transport.
- The transport cycle maintains cosubstrate coupling via a mechanism other than translocation inhibition.
- Cooperative binding is a potential mechanism for optimizing transport in secondary active transporters.
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