title: Dynamic Coupling and Allosteric Networks in the α Subunit of Heterotrimeric G Proteins.
abstract: G protein α subunits cycle between active and inactive conformations to regulate a multitude of intracellular signaling cascades. Important structural transitions occurring during this cycle have been characterized from extensive crystallographic studies. However, the link between observed conformations and the allosteric regulation of binding events at distal sites critical for signaling through G proteins remain unclear. Here we describe molecular dynamics simulations, bioinformatics analysis, and experimental mutagenesis that identifies residues involved in mediating the allosteric coupling of receptor, nucleotide, and helical domain interfaces of Gαi. Most notably, we predict and characterize novel allosteric decoupling mutants, which display enhanced helical domain opening, increased rates of nucleotide exchange, and constitutive activity in the absence of receptor activation. Collectively, our results provide a framework for explaining how binding events and mutations can alter internal dynamic couplings critical for G protein function.
authors.affiliation: From the Department of Computational Medicine and Bioinformatics.
authors.forename: Xin-Qiu
authors.initials: XQ
authors.lastname: Yao
authors.affiliation: Cell and Developmental Biology, and the Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, Minnesota 55455.
authors.forename: Rabia U
authors.initials: RU
authors.lastname: Malik
authors.affiliation: Pharmacology, University of Michigan, Ann Arbor, Michigan 48109.
authors.forename: Nicholas W
authors.initials: NW
authors.lastname: Griggs
authors.affiliation: the Department of Biomedicine, University of Bergen, 5020 Bergen, Norway, and.
authors.forename: Lars
authors.initials: L
authors.lastname: Skjærven
authors.affiliation: Pharmacology, University of Michigan, Ann Arbor, Michigan 48109.
authors.forename: John R
authors.initials: JR
authors.lastname: Traynor
authors.affiliation: the Department of Genetics, Cell Biology, and Development, University of Minnesota, Minneapolis, Minnesota 55455.
authors.forename: Sivaraj
authors.initials: S
authors.lastname: Sivaramakrishnan
authors.affiliation: From the Department of Computational Medicine and Bioinformatics, bjgrant@umich.edu.
authors.forename: Barry J
authors.initials: BJ
authors.lastname: Grant
mesh_terms: D000494:Allosteric Regulation; D019943:Amino Acid Substitution; D000818:Animals; D001665:Binding Sites; D002417:Cattle; D019295:Computational Biology; D030562:Databases, Protein; D044385:GTP-Binding Protein alpha Subunits / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D008024:Ligands; D051379:Mice; D008958:Models, Molecular; D056004:Molecular Dynamics Simulation; D016297:Mutagenesis, Site-Directed; D050505:Mutant Proteins / Q000737:chemistry / Q000378:metabolism; D025341:Principal Component Analysis; D011487:Protein Conformation; D058767:Protein Unfolding; D051381:Rats; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D061987:Sf9 Cells
chemical_list: D044385:GTP-Binding Protein alpha Subunits; D008024:Ligands; D050505:Mutant Proteins; D011994:Recombinant Proteins
keywords: G protein; allosteric regulation; bioinformatics; molecular dynamics; mutagenesis