title: Dynamic regulation of GDP binding to G proteins revealed by magnetic field-dependent NMR relaxation analyses.
abstract: Heterotrimeric guanine-nucleotide-binding proteins (G proteins) serve as molecular switches in signalling pathways, by coupling the activation of cell surface receptors to intracellular responses. Mutations in the G protein α-subunit (Gα) that accelerate guanosine diphosphate (GDP) dissociation cause hyperactivation of the downstream effector proteins, leading to oncogenesis. However, the structural mechanism of the accelerated GDP dissociation has remained unclear. Here, we use magnetic field-dependent nuclear magnetic resonance relaxation analyses to investigate the structural and dynamic properties of GDP bound Gα on a microsecond timescale. We show that Gα rapidly exchanges between a ground-state conformation, which tightly binds to GDP and an excited conformation with reduced GDP affinity. The oncogenic D150N mutation accelerates GDP dissociation by shifting the equilibrium towards the excited conformation.
authors.affiliation: Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.|Japan Biological Informatics Consortium (JBiC), Aomi, Koto-ku, Tokyo 135-0064, Japan.
authors.forename: Yuki
authors.initials: Y
authors.lastname: Toyama
authors.affiliation: Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Hanaho
authors.initials: H
authors.lastname: Kano
authors.affiliation: Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Yoko
authors.initials: Y
authors.lastname: Mase
authors.affiliation: Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Mariko
authors.initials: M
authors.lastname: Yokogawa
authors.affiliation: Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Masanori
authors.initials: M
authors.lastname: Osawa
authors.affiliation: Graduate School of Pharmaceutical Sciences, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Ichio
authors.initials: I
authors.lastname: Shimada
mesh_terms: D044385:GTP-Binding Protein alpha Subunits / Q000737:chemistry / Q000378:metabolism*; D006153:Guanosine Diphosphate / Q000378:metabolism*; D006801:Humans; D008274:Magnesium / Q000494:pharmacology; D060526:Magnetic Fields; D009682:Magnetic Resonance Spectroscopy; D050505:Mutant Proteins / Q000378:metabolism; D010455:Peptides / Q000378:metabolism; D011487:Protein Conformation
chemical_list: D044385:GTP-Binding Protein alpha Subunits; D050505:Mutant Proteins; D010455:Peptides; D006153:Guanosine Diphosphate; D008274:Magnesium