Limits...
Small molecules with similar structures exhibit agonist, neutral antagonist or inverse agonist activity toward angiotensin II type 1 receptor.

Miura S, Kiya Y, Hanzawa H, Nakao N, Fujino M, Imaizumi S, Matsuo Y, Yanagisawa H, Koike H, Komuro I, Karnik SS, Saku K - PLoS ONE (2012)

Bottom Line: The results of substituted cysteine accessibility mapping studies support the novel concept that ligand-induced changes in the conformation of TM3 play a role in stabilizing GPCR.Although the agonist-, neutral antagonist and inverse agonist-binding sites in the AT(1) receptor are similar, each ligand induced specific conformational changes in TM3.In addition, all of the experimental data were obtained with functional receptors in a native membrane environment (in situ).

View Article: PubMed Central - PubMed

Affiliation: Department of Cardiology, Fukuoka University School of Medicine, Fukuoka, Japan. miuras@cis.fukuoka-u.ac.jp

ABSTRACT
Small differences in the chemical structures of ligands can be responsible for agonism, neutral antagonism or inverse agonism toward a G-protein-coupled receptor (GPCR). Although each ligand may stabilize the receptor conformation in a different way, little is known about the precise conformational differences. We synthesized the angiotensin II type 1 receptor blocker (ARB) olmesartan, R239470 and R794847, which induced inverse agonism, antagonism and agonism, respectively, and then investigated the ligand-specific changes in the receptor conformation with respect to stabilization around transmembrane (TM)3. The results of substituted cysteine accessibility mapping studies support the novel concept that ligand-induced changes in the conformation of TM3 play a role in stabilizing GPCR. Although the agonist-, neutral antagonist and inverse agonist-binding sites in the AT(1) receptor are similar, each ligand induced specific conformational changes in TM3. In addition, all of the experimental data were obtained with functional receptors in a native membrane environment (in situ).

Show MeSH
Putative binding mode of various ligands in AT1 receptor.Transmenbrane (TM)1–7 are shown as colored ribbons: blue (TM1), cyan (TM2), green (TM3), lime green (TM4), yellow (TM5), orange (TM6) and red (TM7). Sidechains of the focused residues are shown as gray lines, and ligands are represented as magenta sticks. The hydrogen bonds and electrostatic interactions are indicated by yellow dotted lines. The distance between Leu112 and the hydroxyphenyl moiety of R794847 is represented as a green dotted line. The unit of distance was Å. (a) without ligand, (b) olmesartan, (c) R239470, (d) R794847.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3375280&req=5

pone-0037974-g005: Putative binding mode of various ligands in AT1 receptor.Transmenbrane (TM)1–7 are shown as colored ribbons: blue (TM1), cyan (TM2), green (TM3), lime green (TM4), yellow (TM5), orange (TM6) and red (TM7). Sidechains of the focused residues are shown as gray lines, and ligands are represented as magenta sticks. The hydrogen bonds and electrostatic interactions are indicated by yellow dotted lines. The distance between Leu112 and the hydroxyphenyl moiety of R794847 is represented as a green dotted line. The unit of distance was Å. (a) without ligand, (b) olmesartan, (c) R239470, (d) R794847.

Mentions: A molecular model was constructed based on a consideration of the interactions between the AT1 receptor and olmesartan, R239470 or R794847 as suggested from the mutation experiments and the changes in the conformation of TM3 in the AT1 receptor induced by olmesartan, R239470 and R794847 using the SCAM study (Fig. 5). The rotation and tilt of the TM helices are introduced as described in the Methods. The distances between Tyr113 in the AT1 receptor and the hydroxyl group of olmesartan and between Lys199 and the carboxyl group are 3.4 and 2.6 Å, respectively, which are reasonable distances for contributing to electrostatic and/or hydrogen bond interactions. R239470 showed slight changes in these distances (2.9 and 2.8 Å, respectively). In addition, the distances with R794847 were similar to those with R239470 (3.0 and 2.9 Å, respectively). Although R794847 did not show the reduction of binding affinity toward L112A mutant (31±5 nM) compared with WT (48±12 nM), Leu112 was closer to the centroid of the phenol ring of R794847 (3.6 Å) according to molecular modeling. In addition, the other compounds do not have a phenol ring in this position.


Small molecules with similar structures exhibit agonist, neutral antagonist or inverse agonist activity toward angiotensin II type 1 receptor.

Miura S, Kiya Y, Hanzawa H, Nakao N, Fujino M, Imaizumi S, Matsuo Y, Yanagisawa H, Koike H, Komuro I, Karnik SS, Saku K - PLoS ONE (2012)

Putative binding mode of various ligands in AT1 receptor.Transmenbrane (TM)1–7 are shown as colored ribbons: blue (TM1), cyan (TM2), green (TM3), lime green (TM4), yellow (TM5), orange (TM6) and red (TM7). Sidechains of the focused residues are shown as gray lines, and ligands are represented as magenta sticks. The hydrogen bonds and electrostatic interactions are indicated by yellow dotted lines. The distance between Leu112 and the hydroxyphenyl moiety of R794847 is represented as a green dotted line. The unit of distance was Å. (a) without ligand, (b) olmesartan, (c) R239470, (d) R794847.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3375280&req=5

pone-0037974-g005: Putative binding mode of various ligands in AT1 receptor.Transmenbrane (TM)1–7 are shown as colored ribbons: blue (TM1), cyan (TM2), green (TM3), lime green (TM4), yellow (TM5), orange (TM6) and red (TM7). Sidechains of the focused residues are shown as gray lines, and ligands are represented as magenta sticks. The hydrogen bonds and electrostatic interactions are indicated by yellow dotted lines. The distance between Leu112 and the hydroxyphenyl moiety of R794847 is represented as a green dotted line. The unit of distance was Å. (a) without ligand, (b) olmesartan, (c) R239470, (d) R794847.
Mentions: A molecular model was constructed based on a consideration of the interactions between the AT1 receptor and olmesartan, R239470 or R794847 as suggested from the mutation experiments and the changes in the conformation of TM3 in the AT1 receptor induced by olmesartan, R239470 and R794847 using the SCAM study (Fig. 5). The rotation and tilt of the TM helices are introduced as described in the Methods. The distances between Tyr113 in the AT1 receptor and the hydroxyl group of olmesartan and between Lys199 and the carboxyl group are 3.4 and 2.6 Å, respectively, which are reasonable distances for contributing to electrostatic and/or hydrogen bond interactions. R239470 showed slight changes in these distances (2.9 and 2.8 Å, respectively). In addition, the distances with R794847 were similar to those with R239470 (3.0 and 2.9 Å, respectively). Although R794847 did not show the reduction of binding affinity toward L112A mutant (31±5 nM) compared with WT (48±12 nM), Leu112 was closer to the centroid of the phenol ring of R794847 (3.6 Å) according to molecular modeling. In addition, the other compounds do not have a phenol ring in this position.

Bottom Line: The results of substituted cysteine accessibility mapping studies support the novel concept that ligand-induced changes in the conformation of TM3 play a role in stabilizing GPCR.Although the agonist-, neutral antagonist and inverse agonist-binding sites in the AT(1) receptor are similar, each ligand induced specific conformational changes in TM3.In addition, all of the experimental data were obtained with functional receptors in a native membrane environment (in situ).

View Article: PubMed Central - PubMed

Affiliation: Department of Cardiology, Fukuoka University School of Medicine, Fukuoka, Japan. miuras@cis.fukuoka-u.ac.jp

ABSTRACT
Small differences in the chemical structures of ligands can be responsible for agonism, neutral antagonism or inverse agonism toward a G-protein-coupled receptor (GPCR). Although each ligand may stabilize the receptor conformation in a different way, little is known about the precise conformational differences. We synthesized the angiotensin II type 1 receptor blocker (ARB) olmesartan, R239470 and R794847, which induced inverse agonism, antagonism and agonism, respectively, and then investigated the ligand-specific changes in the receptor conformation with respect to stabilization around transmembrane (TM)3. The results of substituted cysteine accessibility mapping studies support the novel concept that ligand-induced changes in the conformation of TM3 play a role in stabilizing GPCR. Although the agonist-, neutral antagonist and inverse agonist-binding sites in the AT(1) receptor are similar, each ligand induced specific conformational changes in TM3. In addition, all of the experimental data were obtained with functional receptors in a native membrane environment (in situ).

Show MeSH