3D7M

Crystal Structure of the G Protein Fast-Exchange Double Mutant I56C/Q333C


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.9 Å
  • R-Value Free: 0.294 
  • R-Value Work: 0.249 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Helix dipole movement and conformational variability contribute to allosteric GDP release in Galphai subunits.

Preininger, A.M.Funk, M.A.Oldham, W.M.Meier, S.M.Johnston, C.A.Adhikary, S.Kimple, A.J.Siderovski, D.P.Hamm, H.E.Iverson, T.M.

(2009) Biochemistry 48: 2630-2642

  • DOI: 10.1021/bi801853a

  • PubMed Abstract: 
  • Heterotrimeric G proteins (Galphabetagamma) transmit signals from activated G protein-coupled receptors (GPCRs) to downstream effectors through a guanine nucleotide signaling cycle. Numerous studies indicate that the carboxy-terminal alpha5 helix of ...

    Heterotrimeric G proteins (Galphabetagamma) transmit signals from activated G protein-coupled receptors (GPCRs) to downstream effectors through a guanine nucleotide signaling cycle. Numerous studies indicate that the carboxy-terminal alpha5 helix of Galpha subunits participates in Galpha-receptor binding, and previous EPR studies suggest this receptor-mediated interaction induces a rotation and translation of the alpha5 helix of the Galpha subunit [Oldham, W. M., et al. (2006) Nat. Struct. Mol. Biol. 13, 772-777]. On the basis of this result, an engineered disulfide bond was designed to constrain the alpha5 helix of Galpha(i1) into its EPR-measured receptor-associated conformation through the introduction of cysteines at position 56 in the alpha1 helix and position 333 in the alpha5 helix (I56C/Q333C Galpha(i1)). A functional mimetic of the EPR-measured alpha5 helix dipole movement upon receptor association was additionally created by introduction of a positive charge at the amino terminus of this helix, D328R Galpha(i1). Both proteins exhibit a dramatically elevated level of basal nucleotide exchange. The 2.9 A resolution crystal structure of I56C/Q333C Galpha(i1) in complex with GDP-AlF(4)(-) reveals the shift of the alpha5 helix toward the guanine nucleotide binding site that is anticipated by EPR measurements. The structure of the I56C/Q333C Galpha(i1) subunit further revealed altered positions for the switch regions and throughout the Galpha(i1) subunit, accompanied by significantly elevated crystallographic temperature factors. Combined with previous evidence in the literature, the structural analysis supports the critical role of electrostatics of the alpha5 helix dipole and overall conformational variability during nucleotide release.


    Organizational Affiliation

    Department of Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee 37232-6600, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Guanine nucleotide-binding protein G(i), alpha-1 subunit
A
354Rattus norvegicusMutation(s): 2 
Gene Names: Gnai1 (Gnai-1)
Find proteins for P10824 (Rattus norvegicus)
Go to UniProtKB:  P10824
Small Molecules
Ligands 3 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
GDP
Query on GDP

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

Download SDF File 
Download CCD File 
A
TETRAFLUOROALUMINATE ION
Al F4
UYOMQIYKOOHAMK-UHFFFAOYSA-J
 Ligand Interaction
MG
Query on MG

Download SDF File 
Download CCD File 
A
MAGNESIUM ION
Mg
JLVVSXFLKOJNIY-UHFFFAOYSA-N
 Ligand Interaction
External Ligand Annotations 
IDBinding Affinity (Sequence Identity %)
GDPKd: 360 nM PDBBIND
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.9 Å
  • R-Value Free: 0.294 
  • R-Value Work: 0.249 
  • Space Group: P 43 21 2
Unit Cell:
Length (Å)Angle (°)
a = 79.659α = 90.00
b = 79.659β = 90.00
c = 114.587γ = 90.00
Software Package:
Software NamePurpose
CNSrefinement
DENZOdata reduction
PHASERphasing
SCALEPACKdata scaling
PDB_EXTRACTdata extraction

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2009-03-03
    Type: Initial release
  • Version 1.1: 2011-07-13
    Type: Version format compliance
  • Version 1.2: 2017-10-25
    Type: Refinement description