2Y4I

KSR2-MEK1 heterodimer


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.46 Å
  • R-Value Free: 0.293 
  • R-Value Work: 0.230 

wwPDB Validation 3D Report Full Report


This is version 1.3 of the entry. See complete history

Literature

A Raf-Induced Allosteric Transition of Ksr Stimulates Ksr and Raf Phosphorylation of Mek

Brennan, D.F.Dar, A.C.Hertz, N.T.Chao, W.Burlingame, A.L.Shokat, K.M.Barford, D.

(2011) Nature 472: 366

  • DOI: 10.1038/nature09860

  • PubMed Abstract: 
  • In metazoans, the Ras-Raf-MEK (mitogen-activated protein-kinase kinase)-ERK (extracellular signal-regulated kinase) signalling pathway relays extracellular stimuli to elicit changes in cellular function and gene expression. Aberrant activation of thi ...

    In metazoans, the Ras-Raf-MEK (mitogen-activated protein-kinase kinase)-ERK (extracellular signal-regulated kinase) signalling pathway relays extracellular stimuli to elicit changes in cellular function and gene expression. Aberrant activation of this pathway through oncogenic mutations is responsible for a large proportion of human cancer. Kinase suppressor of Ras (KSR) functions as an essential scaffolding protein to coordinate the assembly of Raf-MEK-ERK complexes. Here we integrate structural and biochemical studies to understand how KSR promotes stimulatory Raf phosphorylation of MEK (refs 6, 7). We show, from the crystal structure of the kinase domain of human KSR2 (KSR2(KD)) in complex with rabbit MEK1, that interactions between KSR2(KD) and MEK1 are mediated by their respective activation segments and C-lobe αG helices. Analogous to BRAF (refs 8, 9), KSR2 self-associates through a side-to-side interface involving Arg 718, a residue identified in a genetic screen as a suppressor of Ras signalling. ATP is bound to the KSR2(KD) catalytic site, and we demonstrate KSR2 kinase activity towards MEK1 by in vitro assays and chemical genetics. In the KSR2(KD)-MEK1 complex, the activation segments of both kinases are mutually constrained, and KSR2 adopts an inactive conformation. BRAF allosterically stimulates the kinase activity of KSR2, which is dependent on formation of a side-to-side KSR2-BRAF heterodimer. Furthermore, KSR2-BRAF heterodimerization results in an increase of BRAF-induced MEK phosphorylation via the KSR2-mediated relay of a signal from BRAF to release the activation segment of MEK for phosphorylation. We propose that KSR interacts with a regulatory Raf molecule in cis to induce a conformational switch of MEK, facilitating MEK's phosphorylation by a separate catalytic Raf molecule in trans.


    Organizational Affiliation

    Section of Structural Biology, Institute of Cancer Research, Chester Beatty Laboratories, 237 Fulham Road, London SW3 6JB, UK.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
KINASE SUPPRESSOR OF RAS 2
B
319Homo sapiensMutation(s): 0 
Gene Names: KSR2
EC: 2.7.11.1
Find proteins for Q6VAB6 (Homo sapiens)
Go to Gene View: KSR2
Go to UniProtKB:  Q6VAB6
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetails
DUAL SPECIFICITY MITOGEN-ACTIVATED PROTEIN KINASE KINASE 1
C
395Oryctolagus cuniculusMutation(s): 0 
Gene Names: MAP2K1 (MEK1, PRKMK1)
EC: 2.7.12.2
Find proteins for P29678 (Oryctolagus cuniculus)
Go to Gene View: MAP2K1
Go to UniProtKB:  P29678
Small Molecules
Ligands 3 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
ATP
Query on ATP

Download SDF File 
Download CCD File 
B, C
ADENOSINE-5'-TRIPHOSPHATE
C10 H16 N5 O13 P3
ZKHQWZAMYRWXGA-KQYNXXCUSA-N
 Ligand Interaction
CL
Query on CL

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Download CCD File 
C
CHLORIDE ION
Cl
VEXZGXHMUGYJMC-UHFFFAOYSA-M
 Ligand Interaction
MG
Query on MG

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Download CCD File 
B, C
MAGNESIUM ION
Mg
JLVVSXFLKOJNIY-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 3.46 Å
  • R-Value Free: 0.293 
  • R-Value Work: 0.230 
  • Space Group: P 61 2 2
Unit Cell:
Length (Å)Angle (°)
a = 130.565α = 90.00
b = 130.565β = 90.00
c = 221.005γ = 120.00
Software Package:
Software NamePurpose
MOSFLMdata reduction
SCALAdata scaling
CaspRphasing
PHENIXrefinement

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2011-01-19
    Type: Initial release
  • Version 1.1: 2011-05-08
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance
  • Version 1.3: 2017-07-12
    Type: Refinement description