title: Structural basis for regulation of human calcium-sensing receptor by magnesium ions and an unexpected tryptophan derivative co-agonist.
abstract: Ca(2+)-sensing receptors (CaSRs) modulate calcium and magnesium homeostasis and many (patho)physiological processes by responding to extracellular stimuli, including divalent cations and amino acids. We report the first crystal structure of the extracellular domain (ECD) of human CaSR bound with Mg(2+) and a tryptophan derivative ligand at 2.1 Å. The structure reveals key determinants for cooperative activation by metal ions and aromatic amino acids. The unexpected tryptophan derivative was bound in the hinge region between two globular ECD subdomains, and represents a novel high-affinity co-agonist of CaSR. The dissection of structure-function relations by mutagenesis, biochemical, and functional studies provides insights into the molecular basis of human diseases arising from CaSR mutations. The data also provide a novel paradigm for understanding the mechanism of CaSR-mediated signaling that is likely shared by the other family C GPCR [G protein (heterotrimeric guanine nucleotide-binding protein)-coupled receptor] members and can facilitate the development of novel CaSR-based therapeutics.
authors.affiliation: Department of Chemistry, Center for Diagnostics and Therapeutics, Georgia State University, 50 Decatur Street, Atlanta, GA 30303, USA.
authors.forename: Chen
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA.
authors.forename: Tuo
authors.initials: T
authors.lastname: Zhang
authors.affiliation: Department of Chemistry, Center for Diagnostics and Therapeutics, Georgia State University, 50 Decatur Street, Atlanta, GA 30303, USA.
authors.forename: Juan
authors.initials: J
authors.lastname: Zou
authors.affiliation: Department of Chemistry, Center for Diagnostics and Therapeutics, Georgia State University, 50 Decatur Street, Atlanta, GA 30303, USA.
authors.forename: Cassandra Lynn
authors.identifier: 0000-0003-0546-3138
authors.initials: CL
authors.lastname: Miller
authors.affiliation: Department of Chemistry, Center for Diagnostics and Therapeutics, Georgia State University, 50 Decatur Street, Atlanta, GA 30303, USA.
authors.forename: Rakshya
authors.initials: R
authors.lastname: Gorkhali
authors.affiliation: Department of Biochemistry and Molecular Biology and the Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA 30602, USA.
authors.forename: Jeong-Yeh
authors.identifier: 0000-0001-7898-1337
authors.initials: JY
authors.lastname: Yang
authors.affiliation: Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA.
authors.forename: Anthony
authors.identifier: 0000-0001-7069-7120
authors.initials: A
authors.lastname: Schilmiller
authors.affiliation: Department of Biochemistry and Molecular Biology and the Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA 30602, USA.
authors.forename: Shuo
authors.initials: S
authors.lastname: Wang
authors.affiliation: Department of Chemistry, Center for Diagnostics and Therapeutics, Georgia State University, 50 Decatur Street, Atlanta, GA 30303, USA.
authors.forename: Kenneth
authors.identifier: 0000-0002-0317-5549
authors.initials: K
authors.lastname: Huang
authors.affiliation: Division of Endocrinology, Diabetes and Hypertension, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, 221 Longwood Avenue, Boston, MA 02115, USA.
authors.forename: Edward M
authors.initials: EM
authors.lastname: Brown
authors.affiliation: Department of Biochemistry and Molecular Biology and the Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, GA 30602, USA.
authors.forename: Kelley W
authors.identifier: 0000-0003-1768-582X
authors.initials: KW
authors.lastname: Moremen
authors.affiliation: Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI 48824, USA.; Department of Chemistry, Michigan State University, East Lansing, MI 48824, USA.
authors.forename: Jian
authors.initials: J
authors.lastname: Hu
authors.affiliation: Department of Chemistry, Center for Diagnostics and Therapeutics, Georgia State University, 50 Decatur Street, Atlanta, GA 30303, USA.
authors.forename: Jenny J
authors.initials: JJ
authors.lastname: Yang
mesh_terms: D002460:Cell Line; D006801:Humans; D007477:Ions / Q000737:chemistry* / Q000378:metabolism; D008024:Ligands; D008274:Magnesium / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D008968:Molecular Conformation; D009154:Mutation; D011485:Protein Binding; D044169:Receptors, Calcium-Sensing / Q000819:agonists / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D013329:Structure-Activity Relationship; D014364:Tryptophan / Q000031:analogs & derivatives / Q000737:chemistry* / Q000378:metabolism
chemical_list: D007477:Ions; D008024:Ligands; D044169:Receptors, Calcium-Sensing; D014364:Tryptophan; D008274:Magnesium
keywords: Binding Affinity; Calcium Sensing Receptor; Crystal Structure; EC50; L-Phe; Mg2+; TNCA