4MVD

Crystal Structure of a Mammalian Cytidylyltransferase


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 8 Å
  • R-Value Free: 0.407 
  • R-Value Work: 0.379 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history

Literature

Structural Basis for Autoinhibition of CTP:Phosphocholine Cytidylyltransferase (CCT), the Regulatory Enzyme in Phosphatidylcholine Synthesis, by Its Membrane-binding Amphipathic Helix.

Lee, J.Taneva, S.G.Holland, B.W.Tieleman, D.P.Cornell, R.B.

(2014) J.Biol.Chem. 289: 1742-1755

  • DOI: 10.1074/jbc.M113.526970
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • CTP:phosphocholine cytidylyltransferase (CCT) interconverts between an inactive soluble and active membrane-bound form in response to changes in membrane lipid composition. Activation involves disruption of an inhibitory interaction between the αE he ...

    CTP:phosphocholine cytidylyltransferase (CCT) interconverts between an inactive soluble and active membrane-bound form in response to changes in membrane lipid composition. Activation involves disruption of an inhibitory interaction between the αE helices at the base of the active site and an autoinhibitory (AI) segment in the regulatory M domain and membrane insertion of the M domain as an amphipathic helix. We show that in the CCT soluble form the AI segment functions to suppress kcat and elevate the Km for CTP. The crystal structure of a CCT dimer composed of the catalytic and AI segments reveals an AI-αE interaction as a cluster of four amphipathic helices (two αE and two AI helices) at the base of the active sites. This interaction corroborates mutagenesis implicating multiple hydrophobic residues within the AI segment that contribute to its silencing function. The AI-αE interaction directs the turn at the C-terminal end of the AI helix into backbone-to-backbone contact with a loop (L2) at the opening to the active site, which houses the key catalytic residue, lysine 122. Molecular dynamics simulations suggest that lysine 122 side-chain orientations are constrained by contacts with the AI helix-turn, which could obstruct its engagement with substrates. This work deciphers how the CCT regulatory amphipathic helix functions as a silencing device.


    Organizational Affiliation

    From the Departments of Molecular Biology and Biochemistry and.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Choline-phosphate cytidylyltransferase A
B, A, D, C, F, E, H, G
332Rattus 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 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
CDC
Query on CDC

Download SDF File 
Download CCD File 
A, B, C, D, E, F, G, H
[2-CYTIDYLATE-O'-PHOSPHONYLOXYL]-ETHYL-TRIMETHYL-AMMONIUM
C14 H26 N4 O11 P2
RZZPDXZPRHQOCG-OJAKKHQRSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 8 Å
  • R-Value Free: 0.407 
  • R-Value Work: 0.379 
  • Space Group: P 43
Unit Cell:
Length (Å)Angle (°)
a = 107.780α = 90.00
b = 107.780β = 90.00
c = 575.710γ = 90.00
Software Package:
Software NamePurpose
MXdata collection
MOSFLMdata reduction
PHASERphasing
REFMACrefinement
SCALAdata scaling

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

  • Deposited Date: 2013-09-23 
  • Released Date: 2013-12-11 
  • Deposition Author(s): Lee, J., Cornell, R.B.

Revision History 

  • Version 1.0: 2013-12-11
    Type: Initial release
  • Version 1.1: 2014-02-05
    Type: Database references