3HL4

Crystal structure of a mammalian CTP:phosphocholine cytidylyltransferase with CDP-choline


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.2 Å
  • R-Value Free: 0.266 
  • R-Value Work: 0.220 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history

Literature

Crystal Structure of a mammalian CTP: Phosphocholine cytidylyltransferase catalytic domain reveals novel active site residues within a highly conserved nucleotidyl-transferase fold

Lee, J.Johnson, J.E.Ding, Z.Paetzel, M.Cornell, R.B.

(2009) J.Biol.Chem. 284: 33535-33548

  • DOI: 10.1074/jbc.M109.053363

  • PubMed Abstract: 
  • CTP:phosphocholine cytidylyltransferase (CCT) is the key regulatory enzyme in the synthesis of phosphatidylcholine, the most abundant phospholipid in eukaryotic cell membranes. The CCT-catalyzed transfer of a cytidylyl group from CTP to phosphocholin ...

    CTP:phosphocholine cytidylyltransferase (CCT) is the key regulatory enzyme in the synthesis of phosphatidylcholine, the most abundant phospholipid in eukaryotic cell membranes. The CCT-catalyzed transfer of a cytidylyl group from CTP to phosphocholine to form CDP-choline is regulated by a membrane lipid-dependent mechanism imparted by its C-terminal membrane binding domain. We present the first analysis of a crystal structure of a eukaryotic CCT. A deletion construct of rat CCTalpha spanning residues 1-236 (CCT236) lacks the regulatory domain and as a result displays constitutive activity. The 2.2-A structure reveals a CCT236 homodimer in complex with the reaction product, CDP-choline. Each chain is composed of a complete catalytic domain with an intimately associated N-terminal extension, which together with the catalytic domain contributes to the dimer interface. Although the CCT236 structure reveals elements involved in binding cytidine that are conserved with other members of the cytidylyltransferase superfamily, it also features nonconserved active site residues, His-168 and Tyr-173, that make key interactions with the beta-phosphate of CDP-choline. Mutagenesis and kinetic analyses confirmed their role in phosphocholine binding and catalysis. These results demonstrate structural and mechanistic differences in a broadly conserved protein fold across the cytidylyltransferase family. Comparison of the CCT236 structure with those of other nucleotidyltransferases provides evidence for substrate-induced active site loop movements and a disorder-to-order transition of a loop element in the catalytic mechanism.


    Organizational Affiliation

    Department of Molecular Biology and Biochemistry, British Columbia V5A 1S6, Canada.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Choline-phosphate cytidylyltransferase A
A, B
236Rattus norvegicusMutation(s): 0 
Gene Names: Pcyt1a (Ctpct, Pcyt1)
EC: 2.7.7.15
Find proteins for P19836 (Rattus norvegicus)
Go to UniProtKB:  P19836
Small Molecules
Ligands 3 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
FMT
Query on FMT

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Download CCD File 
A, B
FORMIC ACID
C H2 O2
BDAGIHXWWSANSR-UHFFFAOYSA-N
 Ligand Interaction
CDC
Query on CDC

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Download CCD File 
A, B
[2-CYTIDYLATE-O'-PHOSPHONYLOXYL]-ETHYL-TRIMETHYL-AMMONIUM
C14 H26 N4 O11 P2
RZZPDXZPRHQOCG-OJAKKHQRSA-N
 Ligand Interaction
GOL
Query on GOL

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Download CCD File 
A
GLYCEROL
GLYCERIN; PROPANE-1,2,3-TRIOL
C3 H8 O3
PEDCQBHIVMGVHV-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.2 Å
  • R-Value Free: 0.266 
  • R-Value Work: 0.220 
  • Space Group: P 21 21 2
Unit Cell:
Length (Å)Angle (°)
a = 88.973α = 90.00
b = 129.348β = 90.00
c = 43.565γ = 90.00
Software Package:
Software NamePurpose
HKL-2000data reduction
REFMACrefinement
HKL-2000data collection
HKL-2000data scaling
SOLVEphasing

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2009-09-22
    Type: Initial release
  • Version 1.1: 2011-07-13
    Type: Non-polymer description, Version format compliance