title: SIGNAL TRANSDUCTION. Structural basis for nucleotide exchange in heterotrimeric G proteins.
abstract: G protein-coupled receptors (GPCRs) relay diverse extracellular signals into cells by catalyzing nucleotide release from heterotrimeric G proteins, but the mechanism underlying this quintessential molecular signaling event has remained unclear. Here we use atomic-level simulations to elucidate the nucleotide-release mechanism. We find that the G protein α subunit Ras and helical domains-previously observed to separate widely upon receptor binding to expose the nucleotide-binding site-separate spontaneously and frequently even in the absence of a receptor. Domain separation is necessary but not sufficient for rapid nucleotide release. Rather, receptors catalyze nucleotide release by favoring an internal structural rearrangement of the Ras domain that weakens its nucleotide affinity. We use double electron-electron resonance spectroscopy and protein engineering to confirm predictions of our computationally determined mechanism.
authors.affiliation: D. E. Shaw Research, New York, NY 10036, USA. ron.dror@deshawresearch.com david.shaw@deshawresearch.com.
authors.forename: Ron O
authors.initials: RO
authors.lastname: Dror
authors.affiliation: D. E. Shaw Research, New York, NY 10036, USA.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Mildorf
authors.affiliation: Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA.
authors.forename: Daniel
authors.initials: D
authors.lastname: Hilger
authors.affiliation: Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA.
authors.forename: Aashish
authors.initials: A
authors.lastname: Manglik
authors.affiliation: D. E. Shaw Research, New York, NY 10036, USA.
authors.forename: David W
authors.initials: DW
authors.lastname: Borhani
authors.affiliation: D. E. Shaw Research, New York, NY 10036, USA.
authors.forename: Daniel H
authors.initials: DH
authors.lastname: Arlow
authors.affiliation: D. E. Shaw Research, New York, NY 10036, USA.
authors.forename: Ansgar
authors.initials: A
authors.lastname: Philippsen
authors.affiliation: Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Villanueva
authors.affiliation: Jules Stein Eye Institute and Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA.
authors.forename: Zhongyu
authors.initials: Z
authors.lastname: Yang
authors.affiliation: Jules Stein Eye Institute and Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA.
authors.forename: Michael T
authors.initials: MT
authors.lastname: Lerch
authors.affiliation: Jules Stein Eye Institute and Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA.
authors.forename: Wayne L
authors.initials: WL
authors.lastname: Hubbell
authors.affiliation: Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA.
authors.forename: Brian K
authors.initials: BK
authors.lastname: Kobilka
authors.affiliation: Department of Pharmacology, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
authors.forename: Roger K
authors.initials: RK
authors.lastname: Sunahara
authors.affiliation: D. E. Shaw Research, New York, NY 10036, USA. Department of Biochemistry and Molecular Biophysics, Columbia University, New York, NY 10032, USA. ron.dror@deshawresearch.com david.shaw@deshawresearch.com.
authors.forename: David E
authors.initials: DE
authors.lastname: Shaw
mesh_terms: D019206:GTP-Binding Protein alpha Subunits, Gi-Go / Q000737:chemistry*; D019205:GTP-Binding Protein alpha Subunits, Gs / Q000737:chemistry*; D020662:Guanine Nucleotide Exchange Factors / Q000737:chemistry*; D006801:Humans; D008956:Models, Chemical; D056004:Molecular Dynamics Simulation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D043562:Receptors, G-Protein-Coupled / Q000737:chemistry*; D015398:Signal Transduction
chemical_list: D020662:Guanine Nucleotide Exchange Factors; D043562:Receptors, G-Protein-Coupled; D019206:GTP-Binding Protein alpha Subunits, Gi-Go; D019205:GTP-Binding Protein alpha Subunits, Gs