Enhanced structure/function of mTSPO translocator in lipid:surfactant mixed micelles
Abstract
TSPO is a ubiquitous transmembrane protein used as a pharmacological marker in neuroimaging. The only known atomic structure of mammalian TSPOs comes from the solution NMR of mouse TSPO (mTSPO) bound to the PK11195 ligand and in a DPC surfactant environment. No structure is available in a biomimetic environment and without PK11195 which strongly stiffens the protein. We measured the effect of different amphiphilic environments on ligand-free mTSPO to study its structure/function and find optimal solubilization conditions. By replacing the SDS surfactant, where the recombinant protein is purified, with mixed lipid:surfactant (DMPC:DPC) micelles at different ratios (0:1, 1:2 and 2:1, w:w), the α-helix content and interactions and the intrinsic tryptophan (Trp) fluorescence of mTSPO are gradually increased. Small-angle X-ray scattering (SAXS) shows a more extended mTSPO/belt complex with the addition of lipids: Dmax ∼95 Å in DPC alone versus ∼142 Å in DMPC:DPC (1:2). SEC-MALLS shows that the molecular composition of the mTSPO belt is ∼98 molecules for DPC alone and ∼58 DMPC and ∼175 DPC for DMPC:DPC (1:2). Additionally, DMPC:DPC micelles stabilize mTSPO compared to DPC alone, where the protein has a greater propensity to aggregate. These structural changes are consistent with the increased affinity of mTSPO for the PK11195 ligand in presence of lipids (Kd ∼70 μM in DPC alone versus ∼0.91 μM in DMPC:DPC, 1:2), as measured by microscale thermophoresis (MST). In conclusion, mixed lipid:surfactant micelles open new possibilities for the stabilization of membrane proteins and for their study in solution in a more biomimetic amphiphilic environment.
Related
- Assembly and Interfacial Behavior of Recombinant Surfactant Protein-B in Detergent Micelles and Lipid Monolayers.
- Machine learning optimization of polymeric complex coacervate micelles reveals cell-type-specific formulations for enhanced mRNA delivery
- Human adenine nucleotide translocator isoforms mediate functionally redundant mitochondrial ADP/ATP exchange
- AFM imaging of milk casein micelles: Evidence for structural rearrangement upon acidification
- Structure and function of cyanobacterial Omp85 reveal Toc159/Toc90 as a chloroplast protein import pore
BibTeX
@article{saade2026enhanced,
title = {{Enhanced structure/function of mTSPO translocator in lipid:surfactant mixed micelles}},
author = {Christelle Saade and Alexandre Pozza and Françoise Bonneté and Stéphanie Finet and Viviane Lutz-Bueno and Mark Tully and Paloma Varela and Jean-Jacques Lacapère and Sophie Combet},
journal = {Biochimie},
year = {2026},
month = sep,
doi = {10.1016/j.biochi.2024.04.008},
url = {https://hal.science/hal-05768136v1},
note = {CC BY},
}
RIS
TY - JOUR
TI - Enhanced structure/function of mTSPO translocator in lipid:surfactant mixed micelles
AU - Christelle Saade
AU - Alexandre Pozza
AU - Françoise Bonneté
AU - Stéphanie Finet
AU - Viviane Lutz-Bueno
AU - Mark Tully
AU - Paloma Varela
AU - Jean-Jacques Lacapère
AU - Sophie Combet
PY - 2026
DA - 2026/09/28
JO - Biochimie
DO - 10.1016/j.biochi.2024.04.008
UR - https://hal.science/hal-05768136v1
AB - TSPO is a ubiquitous transmembrane protein used as a pharmacological marker in neuroimaging. The only known atomic structure of mammalian TSPOs comes from the solution NMR of mouse TSPO (mTSPO) bound to the PK11195 ligand and in a DPC surfactant environment. No structure is available in a biomimetic environment and without PK11195 which strongly stiffens the protein. We measured the effect of different amphiphilic environments on ligand-free mTSPO to study its structure/function and find optimal solubilization conditions. By replacing the SDS surfactant, where the recombinant protein is purified, with mixed lipid:surfactant (DMPC:DPC) micelles at different ratios (0:1, 1:2 and 2:1, w:w), the α-helix content and interactions and the intrinsic tryptophan (Trp) fluorescence of mTSPO are gradually increased. Small-angle X-ray scattering (SAXS) shows a more extended mTSPO/belt complex with the addition of lipids: Dmax ∼95 Å in DPC alone versus ∼142 Å in DMPC:DPC (1:2). SEC-MALLS shows that the molecular composition of the mTSPO belt is ∼98 molecules for DPC alone and ∼58 DMPC and ∼175 DPC for DMPC:DPC (1:2). Additionally, DMPC:DPC micelles stabilize mTSPO compared to DPC alone, where the protein has a greater propensity to aggregate. These structural changes are consistent with the increased affinity of mTSPO for the PK11195 ligand in presence of lipids (Kd ∼70 μM in DPC alone versus ∼0.91 μM in DMPC:DPC, 1:2), as measured by microscale thermophoresis (MST). In conclusion, mixed lipid:surfactant micelles open new possibilities for the stabilization of membrane proteins and for their study in solution in a more biomimetic amphiphilic environment.
SN - 0300-9084
SN - 1638-6183
ER -