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Molecular Insights into the Transmembrane Domain of the Thyrotropin Receptor.

Chantreau V, Taddese B, Munier M, Gourdin L, Henrion D, Rodien P, Chabbert M - PLoS ONE (2015)

Bottom Line: Depending on the position of the proline substitution, different effects were observed on membrane expression, glycosylation, constitutive cAMP activity and responses to thyrotropin.TM5 straightened during the equilibration phase and was stable for the remainder of the simulations.Our data support a structural model of the TSHR transmembrane domain with a bulged TM2 and a straight TM5 that is specific of glycoprotein hormone receptors.

View Article: PubMed Central - PubMed

Affiliation: UMR CNRS 6214 -INSERM 1083, Laboratory of Integrated Neurovascular and Mitochondrial Biology, University of Angers, Angers, France.

ABSTRACT
The thyrotropin receptor (TSHR) is a G protein-coupled receptor (GPCR) that is member of the leucine-rich repeat subfamily (LGR). In the absence of crystal structure, the success of rational design of ligands targeting the receptor internal cavity depends on the quality of the TSHR models built. In this subfamily, transmembrane helices (TM) 2 and 5 are characterized by the absence of proline compared to most receptors, raising the question of the structural conformation of these helices. To gain insight into the structural properties of these helices, we carried out bioinformatics and experimental studies. Evolutionary analysis of the LGR family revealed a deletion in TM5 but provided no information on TM2. Wild type residues at positions 2.58, 2.59 or 2.60 in TM2 and/or at position 5.50 in TM5 were substituted to proline. Depending on the position of the proline substitution, different effects were observed on membrane expression, glycosylation, constitutive cAMP activity and responses to thyrotropin. Only proline substitution at position 2.59 maintained complex glycosylation and high membrane expression, supporting occurrence of a bulged TM2. The TSHR transmembrane domain was modeled by homology with the orexin 2 receptor, using a protocol that forced the deletion of one residue in the TM5 bulge of the template. The stability of the model was assessed by molecular dynamics simulations. TM5 straightened during the equilibration phase and was stable for the remainder of the simulations. Our data support a structural model of the TSHR transmembrane domain with a bulged TM2 and a straight TM5 that is specific of glycoprotein hormone receptors.

No MeSH data available.


Related in: MedlinePlus

Evolution of LGR receptors.(a) NJ tree of 52 LGR receptors from seven species. The Y5.38 and Y5.39 patterns are indicated by an open and a closed symbol, respectively. (b) Sequence alignment of residues 2.50 to 3.25 and residues 5.38 to 5.58 of the human LGR receptors. The shading corresponds to the alignment of the 52 sequences. Fully conserved positions are shaded in black, partially conserved or type-conserved positions are shaded in dark grey (80% conservation) or light grey (60% conservation).
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pone.0142250.g002: Evolution of LGR receptors.(a) NJ tree of 52 LGR receptors from seven species. The Y5.38 and Y5.39 patterns are indicated by an open and a closed symbol, respectively. (b) Sequence alignment of residues 2.50 to 3.25 and residues 5.38 to 5.58 of the human LGR receptors. The shading corresponds to the alignment of the 52 sequences. Fully conserved positions are shaded in black, partially conserved or type-conserved positions are shaded in dark grey (80% conservation) or light grey (60% conservation).

Mentions: The analysis of class A GPCRs from seven species (two vertebrates: H. sapiens and D. rerio, two chordates: C. intestinalis and B. Floridae, one insect: D. melanogaster, one nematode: C. elegans, and one cnidarian: N. vectensis) led to a set of 52 non-redundant sequences of LGR receptors (sequence identities < 90%). The NJ tree based on the alignment of the transmembrane helices indicates three sub-groups (Fig 2A). The first sub-group includes receptors similar to the glycoprotein hormone receptors and to LGR4-6. The second sub-group includes receptors similar to the relaxin/insulin-like family peptide receptors 1 and 2 (RXFP1/2). These two groups are present from cnidarians to vertebrates. The third sub-group corresponds to an extension of the LGR subfamily specific to C. intestinalis. Analysis of these sequences reveals that the receptors from group 2 have a tyrosine residue at position 5.38, whereas the receptors from groups 1 and 3 have a tyrosine residue at position 5.39 (S1 File).


Molecular Insights into the Transmembrane Domain of the Thyrotropin Receptor.

Chantreau V, Taddese B, Munier M, Gourdin L, Henrion D, Rodien P, Chabbert M - PLoS ONE (2015)

Evolution of LGR receptors.(a) NJ tree of 52 LGR receptors from seven species. The Y5.38 and Y5.39 patterns are indicated by an open and a closed symbol, respectively. (b) Sequence alignment of residues 2.50 to 3.25 and residues 5.38 to 5.58 of the human LGR receptors. The shading corresponds to the alignment of the 52 sequences. Fully conserved positions are shaded in black, partially conserved or type-conserved positions are shaded in dark grey (80% conservation) or light grey (60% conservation).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4636318&req=5

pone.0142250.g002: Evolution of LGR receptors.(a) NJ tree of 52 LGR receptors from seven species. The Y5.38 and Y5.39 patterns are indicated by an open and a closed symbol, respectively. (b) Sequence alignment of residues 2.50 to 3.25 and residues 5.38 to 5.58 of the human LGR receptors. The shading corresponds to the alignment of the 52 sequences. Fully conserved positions are shaded in black, partially conserved or type-conserved positions are shaded in dark grey (80% conservation) or light grey (60% conservation).
Mentions: The analysis of class A GPCRs from seven species (two vertebrates: H. sapiens and D. rerio, two chordates: C. intestinalis and B. Floridae, one insect: D. melanogaster, one nematode: C. elegans, and one cnidarian: N. vectensis) led to a set of 52 non-redundant sequences of LGR receptors (sequence identities < 90%). The NJ tree based on the alignment of the transmembrane helices indicates three sub-groups (Fig 2A). The first sub-group includes receptors similar to the glycoprotein hormone receptors and to LGR4-6. The second sub-group includes receptors similar to the relaxin/insulin-like family peptide receptors 1 and 2 (RXFP1/2). These two groups are present from cnidarians to vertebrates. The third sub-group corresponds to an extension of the LGR subfamily specific to C. intestinalis. Analysis of these sequences reveals that the receptors from group 2 have a tyrosine residue at position 5.38, whereas the receptors from groups 1 and 3 have a tyrosine residue at position 5.39 (S1 File).

Bottom Line: Depending on the position of the proline substitution, different effects were observed on membrane expression, glycosylation, constitutive cAMP activity and responses to thyrotropin.TM5 straightened during the equilibration phase and was stable for the remainder of the simulations.Our data support a structural model of the TSHR transmembrane domain with a bulged TM2 and a straight TM5 that is specific of glycoprotein hormone receptors.

View Article: PubMed Central - PubMed

Affiliation: UMR CNRS 6214 -INSERM 1083, Laboratory of Integrated Neurovascular and Mitochondrial Biology, University of Angers, Angers, France.

ABSTRACT
The thyrotropin receptor (TSHR) is a G protein-coupled receptor (GPCR) that is member of the leucine-rich repeat subfamily (LGR). In the absence of crystal structure, the success of rational design of ligands targeting the receptor internal cavity depends on the quality of the TSHR models built. In this subfamily, transmembrane helices (TM) 2 and 5 are characterized by the absence of proline compared to most receptors, raising the question of the structural conformation of these helices. To gain insight into the structural properties of these helices, we carried out bioinformatics and experimental studies. Evolutionary analysis of the LGR family revealed a deletion in TM5 but provided no information on TM2. Wild type residues at positions 2.58, 2.59 or 2.60 in TM2 and/or at position 5.50 in TM5 were substituted to proline. Depending on the position of the proline substitution, different effects were observed on membrane expression, glycosylation, constitutive cAMP activity and responses to thyrotropin. Only proline substitution at position 2.59 maintained complex glycosylation and high membrane expression, supporting occurrence of a bulged TM2. The TSHR transmembrane domain was modeled by homology with the orexin 2 receptor, using a protocol that forced the deletion of one residue in the TM5 bulge of the template. The stability of the model was assessed by molecular dynamics simulations. TM5 straightened during the equilibration phase and was stable for the remainder of the simulations. Our data support a structural model of the TSHR transmembrane domain with a bulged TM2 and a straight TM5 that is specific of glycoprotein hormone receptors.

No MeSH data available.


Related in: MedlinePlus