3QI2

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


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.797 Å
  • R-Value Free: 0.273 
  • R-Value Work: 0.196 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history

Literature

A P-loop Mutation in Galpha Subunits Prevents Transition to the Active State: Implications for G-protein Signaling in Fungal Pathogenesis

Bosch, D.E.Willard, F.S.Ramanujam, R.Kimple, A.J.Willard, M.D.Naqvi, N.I.Siderovski, D.P.

(2012) Plos Pathog. 8: e1002553-e1002553

  • DOI: 10.1371/journal.ppat.1002553
  • Primary Citation of Related Structures:  

  • 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 su ...

    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.


    Related Citations: 
    • Structure-based protocol for identifying mutations that enhance protein-protein binding affinities.
      Sammond, D.W.,Eletr, Z.M.,Purbeck, C.,Kimple, R.J.,Siderovski, D.P.,Kuhlman, B.
      (2007) J.Mol.Biol. 371: 1392
    • Structural determinants for GoLoco-induced inhibition of nucleotide release by Galpha subunits.
      Kimple, R.J.,Kimple, M.E.,Betts, L.,Sondek, J.,Siderovski, D.P.
      (2002) Nature 416: 878


    Organizational Affiliation

    Department of Pharmacology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Guanine nucleotide-binding protein G(i) subunit alpha-1
A, B
328Homo sapiensMutation(s): 1 
Gene Names: GNAI1
Find proteins for P63096 (Homo sapiens)
Go to Gene View: GNAI1
Go to UniProtKB:  P63096
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetails
Regulator of G-protein signaling 14
C, D
36Homo sapiensMutation(s): 0 
Gene Names: RGS14
Find proteins for O43566 (Homo sapiens)
Go to Gene View: RGS14
Go to UniProtKB:  O43566
Small Molecules
Ligands 3 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
GDP
Query on GDP

Download SDF File 
Download CCD File 
A, B
GUANOSINE-5'-DIPHOSPHATE
C10 H15 N5 O11 P2
QGWNDRXFNXRZMB-UUOKFMHZSA-N
 Ligand Interaction
SO4
Query on SO4

Download SDF File 
Download CCD File 
A, B
SULFATE ION
O4 S
QAOWNCQODCNURD-UHFFFAOYSA-L
 Ligand Interaction
GOL
Query on GOL

Download SDF File 
Download CCD File 
A
GLYCEROL
GLYCERIN; PROPANE-1,2,3-TRIOL
C3 H8 O3
PEDCQBHIVMGVHV-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.797 Å
  • R-Value Free: 0.273 
  • R-Value Work: 0.196 
  • Space Group: C 2 2 21
Unit Cell:
Length (Å)Angle (°)
a = 70.003α = 90.00
b = 131.018β = 90.00
c = 203.307γ = 90.00
Software Package:
Software NamePurpose
HKL-2000data collection
PHASERphasing
HKL-2000data scaling
PHENIXrefinement
HKL-2000data reduction

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2012-02-01
    Type: Initial release
  • Version 1.1: 2012-03-14
    Type: Database references