Glu 2.53(90) of the GnRH receptor is part of the conserved G protein-coupled receptor structure and does not form a salt-bridge with Lys 3.32(121)

• Published in: Molecular and cellular endocrinology Vol. 481; p. 53
• Main Authors: Manilall, Ashmeetha, Stander, B Andre, Madziva, Michael T, Millar, Robert P, Flanagan, Colleen A
• Format: Journal Article
• Language: English
• Published: Ireland 05-02-2019
• Subjects: Amino Acid Substitution; Animals; Chlorocebus aethiops; COS Cells; Crystallography, X-Ray; Glutamine - metabolism; Gonadotropin-Releasing Hormone - metabolism; Humans; Lysine - metabolism; Models, Molecular; Protein Folding; Protein Structure, Secondary; Receptors, LHRH - chemistry; Receptors, LHRH - genetics; Receptors, LHRH - metabolism; G protein-coupled receptor; Receptor structure; GnRH receptor; Interhelical contact
• ISSN: 1872-8057

GnRH receptor mutations, Glu
Lys and Glu
Asp, cause congenital hypogonadotropic hypogonadism. The Glu
side-chain has been proposed to form an intramolecular salt-bridge with Lys
, but conserved intramolecular interaction networks in G protein-coupled receptor crystal structures predict that it interacts with Ser
and Trp
. We investigated interhelical interactions of Glu
that stabilise GnRH receptor folding using functional analyses and computational modelling of mutant receptors. The Glu
Asp mutant was non-functional, but mutants with hydrophobic amino acids or Arg substituted for Glu
were functional, excluding a salt-bridge interaction. The Glu
Arg and Trp
Arg mutants had decreased affinity for GnRH. Models showed that congenital Glu
Lys and Glu
Asp mutations disrupt interactions with Ser
and Trp
respectively, whereas the Glu
Arg and Trp
Arg mutations preserve intramolecular contacts, but increase distance between the transmembrane helices. Our results show that disruption of interhelical contacts that are conserved in G protein-coupled receptors accounts for the effects of some disease-associated GnRH receptor mutations.