Conformational Flexibility in the Transmembrane Protein TSPO

Jaremko, Łukasz; Jaremko, Mariusz; Giller, Karin; Becker, Stefan; Zweckstetter, Markus

doi:10.1002/chem.201502314

Cited by 23 publications

(41 citation statements)

References 48 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As mTSPO is flexible in the absence of high-affinity ligands (Supplementary Fig. 1)2324, reconstitution into liposomes was performed after binding of the small molecule N -(2,5-Dimethoxybenzyl)- N -(5-fluoro-2-phenoxyphenyl)acetamide (DAA1106). According to competition studies, DAA1106 binds to the same binding site as the endogenous TSPO ligand porphyrin and the radioligand PK11195 (ref.…”

Section: Resultsmentioning

confidence: 99%

Cholesterol-mediated allosteric regulation of the mitochondrial translocator protein structure

et al. 2017

Self Cite

View full text Add to dashboard Cite

Cholesterol is an important regulator of membrane protein function. However, the exact mechanisms involved in this process are still not fully understood. Here we study how the tertiary and quaternary structure of the mitochondrial translocator protein TSPO, which binds cholesterol with nanomolar affinity, is affected by this sterol. Residue-specific analysis of TSPO by solid-state NMR spectroscopy reveals a dynamic monomer–dimer equilibrium of TSPO in the membrane. Binding of cholesterol to TSPO's cholesterol-recognition motif leads to structural changes across the protein that shifts the dynamic equilibrium towards the translocator monomer. Consistent with an allosteric mechanism, a mutation within the oligomerization interface perturbs transmembrane regions located up to 35 Å away from the interface, reaching TSPO's cholesterol-binding motif. The lower structural stability of the intervening transmembrane regions provides a mechanistic basis for signal transmission. Our study thus reveals an allosteric signal pathway that connects membrane protein tertiary and quaternary structure with cholesterol binding.

show abstract

Section: Resultsmentioning

confidence: 99%

Cholesterol-mediated allosteric regulation of the mitochondrial translocator protein structure

et al. 2017

Self Cite

View full text Add to dashboard Cite

show abstract

“…The large chemical shift of K39 upon PK 11195 binding supports a strong environment change induced by the ligand. Moreover, based on the available TSPO structural information, with and without ligand [22], together with the hindered location of the binding pocket, we can speculate on a potential conformational change involving hydrophobic interactions between PK 11195 and the aromatic residues. In line with this, several residues are highly conserved in these regions, among which are the W33 and Y34 parts of the end of TM1.…”

Section: Resultsmentioning

confidence: 99%

“…However, the binding mechanism still remains elusive. The mammalian mTSPO in DPC micelles, studied by NMR, was stabilized upon ligand binding and displayed larger mobility and lower helix packing in the absence of PK 11195 than in its presence [9,22]. Conversely, bacterial Bc TSPO, studied by X-ray crystallography, displayed a similar atomic structure [16] with or without PK 11195.…”

Section: Discussionmentioning

confidence: 99%

Characterization of the High-Affinity Drug Ligand Binding Site of Mouse Recombinant TSPO

Iatmanen-Harbi

Senicourt

Papadopoulos

et al. 2019

IJMS

View full text Add to dashboard Cite

The optimization of translocator protein (TSPO) ligands for Positron Emission Tomography as well as for the modulation of neurosteroids is a critical necessity for the development of TSPO-based diagnostics and therapeutics of neuropsychiatrics and neurodegenerative disorders. Structural hints on the interaction site and ligand binding mechanism are essential for the development of efficient TSPO ligands. Recently published atomic structures of recombinant mammalian and bacterial TSPO1, bound with either the high-affinity drug ligand PK 11195 or protoporphyrin IX, have revealed the membrane protein topology and the ligand binding pocket. The ligand is surrounded by amino acids from the five transmembrane helices as well as the cytosolic loops. However, the precise mechanism of ligand binding remains unknown. Previous biochemical studies had suggested that ligand selectivity and binding was governed by these loops. We performed site-directed mutagenesis to further test this hypothesis and measured the binding affinities. We show that aromatic residues (Y34 and F100) from the cytosolic loops contribute to PK 11195 access to its binding site. Limited proteolytic digestion, circular dichroism and solution two-dimensional (2-D) NMR using selective amino acid labelling provide information on the intramolecular flexibility and conformational changes in the TSPO structure upon PK 11195 binding. We also discuss the differences in the PK 11195 binding affinities and the primary structure between TSPO (TSPO1) and its paralogous gene product TSPO2.

show abstract

“…33 These data suggest that the disordered apo structure of mTSPO results from the conditions of purification and refolding and is not an example of a natively disordered protein as the investigators propose. 45 Considering that the mTSPO was purified in sodium dodecyl sulfate (SDS) before refolding and reconstitution into dodecylphosphocholine (DPC) for the NMR experiments, there are substantive concerns about both the apo- and ligand-induced conformations.…”

Section: Crystal and Nmr Structures: Similarities And Differencesmentioning

confidence: 99%

Translocator Protein 18 kDa (TSPO): An Old Protein with New Functions?

et al. 2016

View full text Add to dashboard Cite

Translocator protein 18 kDa (TSPO) was previously known as the peripheral benzodiazepine receptor (PBR) in eukaryotes, where it is mainly localized to the mitochondrial outer membrane. Considerable evidence indicates that it plays regulatory roles in steroidogenesis and apoptosis and is involved in various human diseases, such as metastatic cancer, Alzheimer’s and Parkinson’s disease, inflammation, and anxiety disorders. Ligands of TSPO are widely used as diagnostic tools and treatment options, despite there being no clear understanding of the function of TSPO. An ortholog in the photosynthetic bacterium Rhodobacter was independently discovered as the tryptophan-rich sensory protein (TspO) and found to play a role in the response to changes in oxygen and light conditions that regulate photosynthesis and respiration. As part of this highly conserved protein family found in all three kingdoms, the rat TSPO is able to rescue the knockout phenotype in Rhodobacter, indicating functional as well as structural conservation. Recently, a major breakthrough in the field was achieved: the determination of atomic-resolution structures of TSPO from different species by several independent groups. This now allows us to reexamine the function of TSPO with a molecular perspective. In this review, we focus on recently determined structures of TSPO and their implications for potential functions of this ubiquitous multifaceted protein. We suggest that TSPO is an ancient bacterial receptor/stress sensor that has developed additional interactions, partners, and roles in its mitochondrial outer membrane environment in eukaryotes.

show abstract

Conformational Flexibility in the Transmembrane Protein TSPO

Cited by 23 publications

References 48 publications

Cholesterol-mediated allosteric regulation of the mitochondrial translocator protein structure

Cholesterol-mediated allosteric regulation of the mitochondrial translocator protein structure

Characterization of the High-Affinity Drug Ligand Binding Site of Mouse Recombinant TSPO

Translocator Protein 18 kDa (TSPO): An Old Protein with New Functions?

Contact Info

Product

Resources

About