6VO7

Crystal structure of PI3K-alpha Ras Binding Domain (RBD)


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.31 Å
  • R-Value Free: 0.255 
  • R-Value Work: 0.197 
  • R-Value Observed: 0.203 

Starting Model: experimental
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This is version 1.3 of the entry. See complete history


Literature

Biophysical and Structural Characterization of Novel RAS-Binding Domains (RBDs) of PI3K alpha and PI3K gamma.

Martinez, N.G.Thieker, D.F.Carey, L.M.Rasquinha, J.A.Kistler, S.K.Kuhlman, B.A.Campbell, S.L.

(2021) J Mol Biol 433: 166838-166838

  • DOI: https://doi.org/10.1016/j.jmb.2021.166838
  • Primary Citation of Related Structures:  
    6VO7

  • PubMed Abstract: 

    Phosphatidylinositol-3-kinases (PI3Ks) are lipid kinases that phosphorylate phosphatidylinositol 4,5-bisphosphate to generate a key lipid second messenger, phosphatidylinositol 3,4,5-bisphosphate. PI3Kα and PI3Kγ require activation by RAS proteins to stimulate signaling pathways that control cellular growth, differentiation, motility and survival. Intriguingly, RAS binding to PI3K isoforms likely differ, as RAS mutations have been identified that discriminate between PI3Kα and PI3Kγ, consistent with low sequence homology (23%) between their RAS binding domains (RBDs). As disruption of the RAS/PI3Kα interaction reduces tumor growth in mice with RAS- and epidermal growth factor receptor driven skin and lung cancers, compounds that interfere with this key interaction may prove useful as anti-cancer agents. However, a structure of PI3Kα bound to RAS is lacking, limiting drug discovery efforts. Expression of full-length PI3K isoforms in insect cells has resulted in low yield and variable activity, limiting biophysical and structural studies of RAS/PI3K interactions. This led us to generate the first RBDs from PI3Kα and PI3Kγ that can be expressed at high yield in bacteria and bind to RAS with similar affinity to full-length PI3K. We also solved a 2.31 Å X-ray crystal structure of the PI3Kα-RBD, which aligns well to full-length PI3Kα. Structural differences between the PI3Kα and PI3Kγ RBDs are consistent with differences in thermal stability and may underly differential RAS recognition and RAS-mediated PI3K activation. These high expression, functional PI3K RBDs will aid in interrogating RAS interactions and could aid in identifying inhibitors of this key interaction.


  • Organizational Affiliation

    Department of Biochemistry & Biophysics, University of North Carolina at Chapel Hill, United States.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Phosphatidylinositol 4,5-bisphosphate 3-kinase catalytic subunit alpha isoform144Homo sapiensMutation(s): 0 
Gene Names: PIK3CA
EC: 2.7.1.153 (PDB Primary Data), 2.7.11.1 (PDB Primary Data), 2.7.1.137 (UniProt)
UniProt & NIH Common Fund Data Resources
Find proteins for P42336 (Homo sapiens)
Explore P42336 
Go to UniProtKB:  P42336
PHAROS:  P42336
GTEx:  ENSG00000121879 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP42336
Sequence Annotations
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.31 Å
  • R-Value Free: 0.255 
  • R-Value Work: 0.197 
  • R-Value Observed: 0.203 
  • Space Group: C 2 2 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 71.548α = 90
b = 83.914β = 90
c = 63.988γ = 90
Software Package:
Software NamePurpose
PHENIXrefinement
HKL-2000data reduction
HKL-2000data scaling
PHASERphasing

Structure Validation

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Entry History & Funding Information

Deposition Data


Funding OrganizationLocationGrant Number
National Institutes of Health/National Cancer Institute (NIH/NCI)United StatesCA203657

Revision History  (Full details and data files)

  • Version 1.0: 2021-02-03
    Type: Initial release
  • Version 1.1: 2021-02-17
    Changes: Database references
  • Version 1.2: 2021-03-10
    Changes: Database references
  • Version 1.3: 2023-10-11
    Changes: Data collection, Database references, Refinement description