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Updated: May 12, 2026
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Isolation of Physiologically Active Thylakoids and Their Use in Energy-Dependent Protein Transport Assays
Published on: September 28, 2018
Substrate-induced conformational changes in the S-component ThiT from an energy coupling factor transporter.
Maria Majsnerowska1, Inga Hänelt, Dorith Wunnicke
1Department of Biochemistry, Groningen Biomolecular Sciences and Biotechnology Institute, Netherlands Proteomics Centre and Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands.
Structure (London, England : 1993)
|April 23, 2013
Summary
Energy coupling factor transporters utilize S-components for high-affinity vitamin binding. Structural studies reveal thiamin binding causes conformational changes in Lactococcus lactis ThiT
Area of Science:
- Biochemistry
- Structural Biology
- Microbiology
Background:
- Energy coupling factor (ECF) transporters are a novel class of ABC transporters crucial for prokaryotic vitamin uptake.
- ECF transporters comprise small integral membrane proteins (S-components) with high substrate affinity, associated with EcfT and ATPases.
Purpose of the Study:
- To elucidate the structural rearrangements in the Lactococcus lactis S-component, ThiT, upon thiamin binding.
- To understand the mechanism of substrate binding in solitary ECF S-components.
Main Methods:
- Electron Paramagnetic Resonance (EPR) spectroscopy
- Stopped-flow fluorescence spectroscopy
- Molecular dynamics simulations
Main Results:
- Thiamin binding induces conformational changes specifically in the loop between transmembrane helices 1 and 2 of ThiT.
- This loop acts as a lid, occluding the substrate binding site upon thiamin interaction.
- Solitary ThiT functions as a high-affinity thiamin binding protein but lacks an intrinsic translocation pathway.
Conclusions:
- The S-component ThiT binds thiamin with high affinity through a lid-like mechanism involving a transmembrane loop.
- ECF S-components are primarily substrate-binding modules, with translocation likely mediated by other components of the ECF transporter complex.
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