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Active state-like conformational elements in the beta2-AR and a photoactivated intermediate of rhodopsin identified by dynamic properties of GPCRs.

Han DS, Wang SX, Weinstein H - Biochemistry (2008)

Bottom Line: G-Protein-coupled receptors (GPCRs) adopt various functionally relevant conformational states in cell signaling processes.Recently determined crystal structures of rhodopsin and the beta 2-adrenergic receptor (beta 2-AR) offer insight into previously uncharacterized active conformations, but the molecular states of these GPCRs are likely to contain both inactive and active-like conformational elements.We have identified conformational rearrangements in the dynamics of the TM7-HX8 segment that relate to the properties of the conserved NPxxY(x)5,6F motif and show that they can be used to identify active state-like conformational elements in the corresponding regions of the new structures of rhodopsin and the beta 2-AR.

View Article: PubMed Central - PubMed

Affiliation: Department of Physiology and Biophysics, Weill Medical College, Cornell University, 1300 York Avenue, New York, New York 10021, USA.

ABSTRACT
G-Protein-coupled receptors (GPCRs) adopt various functionally relevant conformational states in cell signaling processes. Recently determined crystal structures of rhodopsin and the beta 2-adrenergic receptor (beta 2-AR) offer insight into previously uncharacterized active conformations, but the molecular states of these GPCRs are likely to contain both inactive and active-like conformational elements. We have identified conformational rearrangements in the dynamics of the TM7-HX8 segment that relate to the properties of the conserved NPxxY(x)5,6F motif and show that they can be used to identify active state-like conformational elements in the corresponding regions of the new structures of rhodopsin and the beta 2-AR.

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Energies of interaction between portions of rhodopsin averaged over the course of the simulation. For the simulations performed in triplicate (Y7.53F, Y7.53N, F7.60A, and Y7.53F/F7.60A), the results represent averages over all of the relevant simulations. The interaction energies were calculated between the following sets of residues: (A) TM7 (7.49−7.56) and HX8 (7.60−7.70), (B) residues at positions 7.53 and 7.60, (C) TM7 (7.49−7.56) and TM2 (2.40−2.50), (D) residues at positions 7.53 and N2.40, and (E) residues at positions 7.53 and L2.43. (F) The color panel shows a representative snapshot of the cytoplasmic ends of TM7 and TM2 from the WT simulation compared to the same region in the β2-AR structure (yellow). The relative positions of residues Y7.53, N2.40, and L2.43 (I in the β2-AR) in the two structures suggest a weakened interaction in the β2-AR structure. Cα atoms corresponding to positions 7.50−7.57 and 2.40−2.43 were used to fit the structures onto each other.
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fig2: Energies of interaction between portions of rhodopsin averaged over the course of the simulation. For the simulations performed in triplicate (Y7.53F, Y7.53N, F7.60A, and Y7.53F/F7.60A), the results represent averages over all of the relevant simulations. The interaction energies were calculated between the following sets of residues: (A) TM7 (7.49−7.56) and HX8 (7.60−7.70), (B) residues at positions 7.53 and 7.60, (C) TM7 (7.49−7.56) and TM2 (2.40−2.50), (D) residues at positions 7.53 and N2.40, and (E) residues at positions 7.53 and L2.43. (F) The color panel shows a representative snapshot of the cytoplasmic ends of TM7 and TM2 from the WT simulation compared to the same region in the β2-AR structure (yellow). The relative positions of residues Y7.53, N2.40, and L2.43 (I in the β2-AR) in the two structures suggest a weakened interaction in the β2-AR structure. Cα atoms corresponding to positions 7.50−7.57 and 2.40−2.43 were used to fit the structures onto each other.

Mentions: Surprisingly, it is not the TM7−HX8 interaction energy (Figure 2A) that correlates best with the expected phenotypes of the mutants (Table 1). This interaction energy remains virtually identical in the WT and in the mutants that exhibited the most dramatic phenotypes, locked-on Y7.53N and locked-off Y7.53F. Only the F7.60A substitution, which had little effect on the phenotype in 5-HT2C, significantly diminishes the energy of interaction between TM7 and HX8 (Figure 2A). The specific residue−residue interactions between positions 7.53 and 7.60 are consistent with these findings and show that the F7.60A mutation, but not Y7.53F or Y7.53N, leads to a significant loss of interaction energy relative to that of the WT (Figure 2B), accounting for the majority of the change in the energy of interaction between TM7 and HX8. This argues against the possibility that the mutations at positions Y7.53 and F7.60, which lead to changes in rhodopsin conformation, do so by disrupting the interaction between the two residues (21). Interactions among other residues in this local environment are likely associated with the phenotypes observed in 5-HT2C (19).


Active state-like conformational elements in the beta2-AR and a photoactivated intermediate of rhodopsin identified by dynamic properties of GPCRs.

Han DS, Wang SX, Weinstein H - Biochemistry (2008)

Energies of interaction between portions of rhodopsin averaged over the course of the simulation. For the simulations performed in triplicate (Y7.53F, Y7.53N, F7.60A, and Y7.53F/F7.60A), the results represent averages over all of the relevant simulations. The interaction energies were calculated between the following sets of residues: (A) TM7 (7.49−7.56) and HX8 (7.60−7.70), (B) residues at positions 7.53 and 7.60, (C) TM7 (7.49−7.56) and TM2 (2.40−2.50), (D) residues at positions 7.53 and N2.40, and (E) residues at positions 7.53 and L2.43. (F) The color panel shows a representative snapshot of the cytoplasmic ends of TM7 and TM2 from the WT simulation compared to the same region in the β2-AR structure (yellow). The relative positions of residues Y7.53, N2.40, and L2.43 (I in the β2-AR) in the two structures suggest a weakened interaction in the β2-AR structure. Cα atoms corresponding to positions 7.50−7.57 and 2.40−2.43 were used to fit the structures onto each other.
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fig2: Energies of interaction between portions of rhodopsin averaged over the course of the simulation. For the simulations performed in triplicate (Y7.53F, Y7.53N, F7.60A, and Y7.53F/F7.60A), the results represent averages over all of the relevant simulations. The interaction energies were calculated between the following sets of residues: (A) TM7 (7.49−7.56) and HX8 (7.60−7.70), (B) residues at positions 7.53 and 7.60, (C) TM7 (7.49−7.56) and TM2 (2.40−2.50), (D) residues at positions 7.53 and N2.40, and (E) residues at positions 7.53 and L2.43. (F) The color panel shows a representative snapshot of the cytoplasmic ends of TM7 and TM2 from the WT simulation compared to the same region in the β2-AR structure (yellow). The relative positions of residues Y7.53, N2.40, and L2.43 (I in the β2-AR) in the two structures suggest a weakened interaction in the β2-AR structure. Cα atoms corresponding to positions 7.50−7.57 and 2.40−2.43 were used to fit the structures onto each other.
Mentions: Surprisingly, it is not the TM7−HX8 interaction energy (Figure 2A) that correlates best with the expected phenotypes of the mutants (Table 1). This interaction energy remains virtually identical in the WT and in the mutants that exhibited the most dramatic phenotypes, locked-on Y7.53N and locked-off Y7.53F. Only the F7.60A substitution, which had little effect on the phenotype in 5-HT2C, significantly diminishes the energy of interaction between TM7 and HX8 (Figure 2A). The specific residue−residue interactions between positions 7.53 and 7.60 are consistent with these findings and show that the F7.60A mutation, but not Y7.53F or Y7.53N, leads to a significant loss of interaction energy relative to that of the WT (Figure 2B), accounting for the majority of the change in the energy of interaction between TM7 and HX8. This argues against the possibility that the mutations at positions Y7.53 and F7.60, which lead to changes in rhodopsin conformation, do so by disrupting the interaction between the two residues (21). Interactions among other residues in this local environment are likely associated with the phenotypes observed in 5-HT2C (19).

Bottom Line: G-Protein-coupled receptors (GPCRs) adopt various functionally relevant conformational states in cell signaling processes.Recently determined crystal structures of rhodopsin and the beta 2-adrenergic receptor (beta 2-AR) offer insight into previously uncharacterized active conformations, but the molecular states of these GPCRs are likely to contain both inactive and active-like conformational elements.We have identified conformational rearrangements in the dynamics of the TM7-HX8 segment that relate to the properties of the conserved NPxxY(x)5,6F motif and show that they can be used to identify active state-like conformational elements in the corresponding regions of the new structures of rhodopsin and the beta 2-AR.

View Article: PubMed Central - PubMed

Affiliation: Department of Physiology and Biophysics, Weill Medical College, Cornell University, 1300 York Avenue, New York, New York 10021, USA.

ABSTRACT
G-Protein-coupled receptors (GPCRs) adopt various functionally relevant conformational states in cell signaling processes. Recently determined crystal structures of rhodopsin and the beta 2-adrenergic receptor (beta 2-AR) offer insight into previously uncharacterized active conformations, but the molecular states of these GPCRs are likely to contain both inactive and active-like conformational elements. We have identified conformational rearrangements in the dynamics of the TM7-HX8 segment that relate to the properties of the conserved NPxxY(x)5,6F motif and show that they can be used to identify active state-like conformational elements in the corresponding regions of the new structures of rhodopsin and the beta 2-AR.

Show MeSH