4DH1

Low temperature X-ray structure of cAMP dependent Protein Kinase A catalytic subunit with low Mg2+, ATP and IP20


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2 Å
  • R-Value Free: 0.234 
  • R-Value Work: 0.199 

wwPDB Validation 3D Report Full Report


This is version 1.3 of the entry. See complete history

Literature

Low- and room-temperature X-ray structures of protein kinase A ternary complexes shed new light on its activity.

Kovalevsky, A.Y.Johnson, H.Hanson, B.L.Waltman, M.J.Fisher, S.Z.Taylor, S.Langan, P.

(2012) Acta Crystallogr.,Sect.D 68: 854-860

  • DOI: 10.1107/S0907444912014886
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • Post-translational protein phosphorylation by protein kinase A (PKA) is a ubiquitous signalling mechanism which regulates many cellular processes. A low-temperature X-ray structure of the ternary complex of the PKA catalytic subunit (PKAc) with ATP a ...

    Post-translational protein phosphorylation by protein kinase A (PKA) is a ubiquitous signalling mechanism which regulates many cellular processes. A low-temperature X-ray structure of the ternary complex of the PKA catalytic subunit (PKAc) with ATP and a 20-residue peptidic inhibitor (IP20) at the physiological Mg(2+) concentration of ∼0.5 mM (LT PKA-MgATP-IP20) revealed a single metal ion in the active site. The lack of a second metal in LT PKA-MgATP-IP20 renders the β- and γ-phosphoryl groups of ATP very flexible, with high thermal B factors. Thus, the second metal is crucial for tight positioning of the terminal phosphoryl group for transfer to a substrate, as demonstrated by comparison of the former structure with that of the LT PKA-Mg(2)ATP-IP20 complex obtained at high Mg(2+) concentration. In addition to its kinase activity, PKAc is also able to slowly catalyze the hydrolysis of ATP using a water molecule as a substrate. It was found that ATP can be readily and completely hydrolyzed to ADP and a free phosphate ion in the crystals of the ternary complex PKA-Mg(2)ATP-IP20 by X-ray irradiation at room temperature. The cleavage of ATP may be aided by X-ray-generated free hydroxyl radicals, a very reactive chemical species, which move rapidly through the crystal at room temperature. The phosphate anion is clearly visible in the electron-density maps; it remains in the active site but slides about 2 Å from its position in ATP towards Ala21 of IP20, which mimics the phosphorylation site. The phosphate thus pushes the peptidic inhibitor away from the product ADP, while resulting in dramatic conformational changes of the terminal residues 24 and 25 of IP20. X-ray structures of PKAc in complex with the nonhydrolysable ATP analogue AMP-PNP at both room and low temperature demonstrated no temperature effects on the conformation and position of IP20.


    Organizational Affiliation

    Bioscience Division, Los Alamos National Laboratory, PO Box 1663, MS M888, Los Alamos, NM 87545, USA. ayk@lanl.gov




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
cAMP-dependent protein kinase catalytic subunit alpha
A
350Mus musculusMutation(s): 0 
Gene Names: Prkaca (Pkaca)
EC: 2.7.11.11
Find proteins for P05132 (Mus musculus)
Go to UniProtKB:  P05132
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetails
cAMP-dependent protein kinase inhibitor alpha
I
20Mus musculusMutation(s): 0 
Gene Names: Pkia
Find proteins for P63248 (Mus musculus)
Go to UniProtKB:  P63248
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
ATP
Query on ATP

Download SDF File 
Download CCD File 
A
ADENOSINE-5'-TRIPHOSPHATE
C10 H16 N5 O13 P3
ZKHQWZAMYRWXGA-KQYNXXCUSA-N
 Ligand Interaction
MG
Query on MG

Download SDF File 
Download CCD File 
A
MAGNESIUM ION
Mg
JLVVSXFLKOJNIY-UHFFFAOYSA-N
 Ligand Interaction
Modified Residues  2 Unique
IDChainsTypeFormula2D DiagramParent
SEP
Query on SEP
A
L-PEPTIDE LINKINGC3 H8 N O6 PSER
TPO
Query on TPO
A
L-PEPTIDE LINKINGC4 H10 N O6 PTHR
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2 Å
  • R-Value Free: 0.234 
  • R-Value Work: 0.199 
  • Space Group: P 21 21 21
Unit Cell:
Length (Å)Angle (°)
a = 58.430α = 90.00
b = 79.920β = 90.00
c = 98.610γ = 90.00
Software Package:
Software NamePurpose
CNSrefinement
CrystalCleardata collection
d*TREKdata scaling
CNSphasing
d*TREKdata reduction

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2012-06-27
    Type: Initial release
  • Version 1.1: 2012-12-12
    Type: Other
  • Version 1.2: 2013-01-23
    Type: Database references
  • Version 1.3: 2013-03-13
    Type: Other