A cation-pi interaction in the binding site of the glycine receptor is mediated by a phenylalanine residue

TY - JOUR

T1 - A cation-pi interaction in the binding site of the glycine receptor is mediated by a phenylalanine residue

AU - Pless, Stephan Alexander

AU - Millen, Kat S

AU - Hanek, Ariele P

AU - Lynch, Joseph W

AU - Lester, Henry A

AU - Lummis, Sarah C R

AU - Dougherty, Dennis A

PY - 2008/10/22

Y1 - 2008/10/22

N2 - Cys-loop receptor binding sites characteristically contain many aromatic amino acids. In nicotinic ACh and 5-HT3 receptors, a Trp residue forms a cation-pi interaction with the agonist, whereas in GABA(A) receptors, a Tyr performs this role. The glycine receptor binding site, however, contains predominantly Phe residues. Homology models suggest that two of these Phe side chains, Phe159 and Phe207, and possibly a third, Phe63, are positioned such that they could contribute to a cation-pi interaction with the primary amine of glycine. Here, we test this hypothesis by incorporation of a series of fluorinated Phe derivatives using unnatural amino acid mutagenesis. The data reveal a clear correlation between the glycine EC(50) value and the cation-pi binding ability of the fluorinated Phe derivatives at position 159, but not at positions 207 or 63, indicating a single cation-pi interaction between glycine and Phe159. The data thus provide an anchor point for locating glycine in its binding site, and demonstrate for the first time a cation-pi interaction between Phe and a neurotransmitter.

AB - Cys-loop receptor binding sites characteristically contain many aromatic amino acids. In nicotinic ACh and 5-HT3 receptors, a Trp residue forms a cation-pi interaction with the agonist, whereas in GABA(A) receptors, a Tyr performs this role. The glycine receptor binding site, however, contains predominantly Phe residues. Homology models suggest that two of these Phe side chains, Phe159 and Phe207, and possibly a third, Phe63, are positioned such that they could contribute to a cation-pi interaction with the primary amine of glycine. Here, we test this hypothesis by incorporation of a series of fluorinated Phe derivatives using unnatural amino acid mutagenesis. The data reveal a clear correlation between the glycine EC(50) value and the cation-pi binding ability of the fluorinated Phe derivatives at position 159, but not at positions 207 or 63, indicating a single cation-pi interaction between glycine and Phe159. The data thus provide an anchor point for locating glycine in its binding site, and demonstrate for the first time a cation-pi interaction between Phe and a neurotransmitter.

KW - Amino Acids, Aromatic

KW - Animals

KW - Binding Sites

KW - Cations

KW - Glycine

KW - Humans

KW - Microinjections

KW - Models, Molecular

KW - Mutagenesis, Site-Directed

KW - Oocytes

KW - Phenylalanine

KW - Protein Binding

KW - Protein Conformation

KW - Protein Structure, Secondary

KW - Radioligand Assay

KW - Receptors, Glycine

KW - Structure-Activity Relationship

KW - Xenopus laevis

U2 - 10.1523/JNEUROSCI.2540-08.2008

DO - 10.1523/JNEUROSCI.2540-08.2008

M3 - Journal article

C2 - 18945901

SN - 0270-6474

VL - 28

SP - 10937

EP - 10942

JO - The Journal of neuroscience : the official journal of the Society for Neuroscience

JF - The Journal of neuroscience : the official journal of the Society for Neuroscience

IS - 43

ER -