title: Structure and dynamics of a constitutively active neurotensin receptor.
abstract: Many G protein-coupled receptors show constitutive activity, resulting in the production of a second messenger in the absence of an agonist; and naturally occurring constitutively active mutations in receptors have been implicated in diseases. To gain insight into mechanistic aspects of constitutive activity, we report here the 3.3 Å crystal structure of a constitutively active, agonist-bound neurotensin receptor (NTSR1) and molecular dynamics simulations of agonist-occupied and ligand-free receptor. Comparison with the structure of a NTSR1 variant that has little constitutive activity reveals uncoupling of the ligand-binding domain from conserved connector residues, that effect conformational changes during GPCR activation. Furthermore, molecular dynamics simulations show strong contacts between connector residue side chains and increased flexibility at the intracellular receptor face as features that coincide with robust signalling in cells. The loss of correlation between the binding pocket and conserved connector residues, combined with altered receptor dynamics, possibly explains the reduced neurotensin efficacy in the constitutively active NTSR1 and a facilitated initial engagement with G protein in the absence of agonist.
authors.affiliation: Membrane Protein Structure Function Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Department of Health and Human Services, Rockville, Maryland 20852, United States.
authors.forename: Brian E
authors.initials: BE
authors.lastname: Krumm
authors.affiliation: Department of Molecular Immunology, Beckman Research Institute of the City of Hope, 1500 E Duarte Road, Duarte, California 91010, United States.
authors.forename: Sangbae
authors.initials: S
authors.lastname: Lee
authors.affiliation: Department of Molecular Immunology, Beckman Research Institute of the City of Hope, 1500 E Duarte Road, Duarte, California 91010, United States.
authors.forename: Supriyo
authors.initials: S
authors.lastname: Bhattacharya
authors.affiliation: Laboratory of Molecular Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland 20892, United States.
authors.forename: Istvan
authors.initials: I
authors.lastname: Botos
authors.affiliation: Membrane Protein Structure Function Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Department of Health and Human Services, Rockville, Maryland 20852, United States.
authors.forename: Courtney F
authors.initials: CF
authors.lastname: White
authors.affiliation: Membrane Protein Structure Function Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Department of Health and Human Services, Rockville, Maryland 20852, United States.
authors.forename: Haijuan
authors.initials: H
authors.lastname: Du
authors.affiliation: Department of Molecular Immunology, Beckman Research Institute of the City of Hope, 1500 E Duarte Road, Duarte, California 91010, United States.
authors.forename: Nagarajan
authors.initials: N
authors.lastname: Vaidehi
authors.affiliation: Membrane Protein Structure Function Unit, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Department of Health and Human Services, Rockville, Maryland 20852, United States.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Grisshammer
mesh_terms: D001665:Binding Sites; D020134:Catalytic Domain; D002460:Cell Line; D019204:GTP-Binding Proteins / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D006860:Hydrogen Bonding; D057927:Hydrophobic and Hydrophilic Interactions; D008024:Ligands; D056004:Molecular Dynamics Simulation; D011485:Protein Binding; D011487:Protein Conformation; D018028:Receptors, Neurotensin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D013329:Structure-Activity Relationship
chemical_list: D008024:Ligands; D018028:Receptors, Neurotensin; D019204:GTP-Binding Proteins