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Title: Structure and dynamics of a constitutively active neurotensin receptor

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. In conclusion, 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:
 [1] ;  [2] ;  [2] ;  [3] ;  [1] ;  [1] ;  [2] ;  [1]
  1. National Inst. of Health (NIH), Rockville, MD (United States). National Inst. of Neurological Disorders and Stroke, Dept. of Health and Human Services
  2. Beckman Research Inst. of the City of Hope, Duarte, CA (United States). Dept. of Molecular Immunology
  3. National Inst. of Health (NIH), Bethesda, MD (United States). National Inst. of Diabetes and Digestive and Kidney Diseases, Lab of Molecular Biology
Publication Date:
Grant/Contract Number:
AC02-06CH11357; AC02-76SF00515; R01-GM097261
Type:
Accepted Manuscript
Journal Name:
Scientific Reports
Additional Journal Information:
Journal Volume: 6; Journal Issue: 12, 2016; Journal ID: ISSN 2045-2322
Publisher:
Nature Publishing Group
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22); USDOE Office of Science (SC), Biological and Environmental Research (BER) (SC-23); National Institutes of Health (NIH)
Country of Publication:
United States
Language:
ENGLISH
Subject:
59 BASIC BIOLOGICAL SCIENCES
OSTI Identifier:
1346248