3QI2

A Galpha P-loop mutation prevents transition to the activated state: G42R bound to RGS14 GoLoco

3QI2 の概要

• エントリーDOI: 10.2210/pdb3qi2/pdb
• 関連するPDBエントリー: 1kjy 1Y3A 2OM2 3QE0
• 分子名称: Guanine nucleotide-binding protein G(i) subunit alpha-1, Regulator of G-protein signaling 14, GUANOSINE-5'-DIPHOSPHATE, ... (6 entities in total)
• 機能のキーワード: rgs14 goloco, ras-like domain, all-helical domain, goloco motif, arginine finger, signaling protein, lipoprotein, transducer, guanine nucleotide dissociation inhibitor, gtp binding, nucleotide binding, adp-ribosylation
• 由来する生物種: Homo sapiens (human); 詳細
• 細胞内の位置: Nucleus (By similarity): P63096 O43566
• タンパク質・核酸の鎖数: 4
• 化学式量合計: 84421.36

構造登録者

Bosch, D.E.,Willard, F.S.,Kimple, A.J.,Miley, M.J.,Siderovski, D.P. (登録日: 2011-01-26, 公開日: 2012-02-01, 最終更新日: 2023-09-13)

主引用文献

Bosch, D.E.,Willard, F.S.,Ramanujam, R.,Kimple, A.J.,Willard, M.D.,Naqvi, N.I.,Siderovski, D.P.
A P-loop Mutation in Galpha Subunits Prevents Transition to the Active State: Implications for G-protein Signaling in Fungal Pathogenesis
Plos Pathog., 8:e1002553-e1002553, 2012

PubMed Abstract: Heterotrimeric G-proteins are molecular switches integral to a panoply of different physiological responses that many organisms make to environmental cues. The switch from inactive to active Gαβγ heterotrimer relies on nucleotide cycling by the Gα subunit: exchange of GTP for GDP activates Gα, whereas its intrinsic enzymatic activity catalyzes GTP hydrolysis to GDP and inorganic phosphate, thereby reverting Gα to its inactive state. In several genetic studies of filamentous fungi, such as the rice blast fungus Magnaporthe oryzae, a G42R mutation in the phosphate-binding loop of Gα subunits is assumed to be GTPase-deficient and thus constitutively active. Here, we demonstrate that Gα(G42R) mutants are not GTPase deficient, but rather incapable of achieving the activated conformation. Two crystal structure models suggest that Arg-42 prevents a typical switch region conformational change upon Gα(i1)(G42R) binding to GDP·AlF(4)(-) or GTP, but rotameric flexibility at this locus allows for unperturbed GTP hydrolysis. Gα(G42R) mutants do not engage the active state-selective peptide KB-1753 nor RGS domains with high affinity, but instead favor interaction with Gβγ and GoLoco motifs in any nucleotide state. The corresponding Gα(q)(G48R) mutant is not constitutively active in cells and responds poorly to aluminum tetrafluoride activation. Comparative analyses of M. oryzae strains harboring either G42R or GTPase-deficient Q/L mutations in the Gα subunits MagA or MagB illustrate functional differences in environmental cue processing and intracellular signaling outcomes between these two Gα mutants, thus demonstrating the in vivo functional divergence of G42R and activating G-protein mutants.

PubMed: 22383884
DOI: 10.1371/journal.ppat.1002553

実験手法

X-RAY DIFFRACTION (2.797 Å)