3LBI

Ras soaked in Magnesium Acetate and back soaked in Calcium Acetate

Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.09 Å
  • R-Value Free: 0.217 
  • R-Value Work: 0.175 
  • R-Value Observed: 0.179 

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Literature

Allosteric modulation of Ras positions Q61 for a direct role in catalysis.

Buhrman, G., Holzapfel, G., Fetics, S., Mattos, C.

(2010) Proc Natl Acad Sci U S A 107: 4931-4936

  • DOI: 10.1073/pnas.0912226107
  • Primary Citation of Related Structures:  
    3K8Y, 3K9N, 3LBH, 3LBI, 3LBN

  • PubMed Abstract: 

    • Ras and its effector Raf are key mediators of the Ras/Raf/MEK/ERK signal transduction pathway. Mutants of residue Q61 impair the GTPase activity of Ras and are found prominently in human cancers. Yet the mechanism through which Q61 contributes to catalysis has been elusive ...

    Ras and its effector Raf are key mediators of the Ras/Raf/MEK/ERK signal transduction pathway. Mutants of residue Q61 impair the GTPase activity of Ras and are found prominently in human cancers. Yet the mechanism through which Q61 contributes to catalysis has been elusive. It is thought to position the catalytic water molecule for nucleophilic attack on the gamma-phosphate of GTP. However, we previously solved the structure of Ras from crystals with symmetry of the space group R32 in which switch II is disordered and found that the catalytic water molecule is present. Here we present a structure of wild-type Ras with calcium acetate from the crystallization mother liquor bound at a site remote from the active site and likely near the membrane. This results in a shift in helix 3/loop 7 and a network of H-bonding interactions that propagates across the molecule, culminating in the ordering of switch II and placement of Q61 in the active site in a previously unobserved conformation. This structure suggests a direct catalytic role for Q61 where it interacts with a water molecule that bridges one of the gamma-phosphate oxygen atoms to the hydroxyl group of Y32 to stabilize the transition state of the hydrolysis reaction. We propose that Raf together with the binding of Ca(2+) and a negatively charged group mimicked in our structure by the acetate molecule induces the ordering of switch I and switch II to complete the active site of Ras.

    Organizational Affiliation: 

    Department of Molecular and Structural Biochemistry, North Carolina State University, 128 Polk Hall-CB 7622, Raleigh, NC 27695, USA.



Macromolecules
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Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
GTPase HRasA166Homo sapiensMutation(s): 0 
Gene Names: HRAS, HRAS1
EC: 3.6.5.2
UniProt & NIH Common Fund Data Resources
Find proteins for P01112 (Homo sapiens)
Explore P01112 
Go to UniProtKB:  P01112
PHAROS:  P01112
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP01112
Protein Feature View
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  • Reference Sequence
Small Molecules
Ligands 4 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
GNP
Query on GNP
Download Ideal Coordinates CCD File 
B [auth A]PHOSPHOAMINOPHOSPHONIC ACID-GUANYLATE ESTER
C10 H17 N6 O13 P3
UQABYHGXWYXDTK-UUOKFMHZSA-N		 Ligand Interaction
ACT
Query on ACT
Download Ideal Coordinates CCD File 
G [auth A]ACETATE ION
C2 H3 O2
QTBSBXVTEAMEQO-UHFFFAOYSA-M		 Ligand Interaction
CA
Query on CA
Download Ideal Coordinates CCD File 
C [auth A],
E [auth A]		CALCIUM ION
Ca
BHPQYMZQTOCNFJ-UHFFFAOYSA-N		 Ligand Interaction
MG
Query on MG
Download Ideal Coordinates CCD File 
D [auth A],
F [auth A]		MAGNESIUM ION
Mg
JLVVSXFLKOJNIY-UHFFFAOYSA-N		 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.09 Å
  • R-Value Free: 0.217 
  • R-Value Work: 0.175 
  • R-Value Observed: 0.179 
  • Space Group: H 3 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 88.716α = 90
b = 88.716β = 90
c = 134.583γ = 120
Software Package:
Software NamePurpose
MAR345dtbdata collection
PHENIXmodel building
PHENIXrefinement
DENZOdata reduction
SCALEPACKdata scaling
PHENIXphasing

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2010-03-02
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Version format compliance