2EG5

The structure of xanthosine methyltransferase


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.2 Å
  • R-Value Free: 0.284 
  • R-Value Work: 0.230 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

The structure of two N-methyltransferases from the caffeine biosynthetic pathway

McCarthy, A.A.McCarthy, J.G.

(2007) Plant Physiol. 144: 879-889

  • DOI: 10.1104/pp.106.094854
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • Caffeine (1,3,7-trimethylxanthine) is a secondary metabolite produced by certain plant species and an important component of coffee (Coffea arabica and Coffea canephora) and tea (Camellia sinensis). Here we describe the structures of two S-adenosyl-l ...

    Caffeine (1,3,7-trimethylxanthine) is a secondary metabolite produced by certain plant species and an important component of coffee (Coffea arabica and Coffea canephora) and tea (Camellia sinensis). Here we describe the structures of two S-adenosyl-l-methionine-dependent N-methyltransferases that mediate caffeine biosynthesis in C. canephora 'robusta', xanthosine (XR) methyltransferase (XMT), and 1,7-dimethylxanthine methyltransferase (DXMT). Both were cocrystallized with the demethylated cofactor, S-adenosyl-L-cysteine, and substrate, either xanthosine or theobromine. Our structures reveal several elements that appear critical for substrate selectivity. Serine-316 in XMT appears central to the recognition of XR. Likewise, a change from glutamine-161 in XMT to histidine-160 in DXMT is likely to have catalytic consequences. A phenylalanine-266 to isoleucine-266 change in DXMT is also likely to be crucial for the discrimination between mono and dimethyl transferases in coffee. These key residues are probably functionally important and will guide future studies with implications for the biosynthesis of caffeine and its derivatives in plants.


    Related Citations: 
    • Cloning, expression, crystallization and preliminary X-ray analysis of the XMT and DXMT N-methyltransferases from Coffea canephora (robusta)
      McCarthy, A.A.,Biget, L.,Lin, C.,Petiard, V.,Tanksley, S.D.,McCarthy, J.G.
      (2007) Acta Crystallogr.,Sect.F 63: 304


    Organizational Affiliation

    European Molecular Biology Laboratory, Grenoble 38042, France. andrewmc@embl.fr




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Xanthosine methyltransferase
A, C, E, G
372Coffea canephoraMutation(s): 0 
Gene Names: XMT1
EC: 2.1.1.158
Find proteins for A4GE69 (Coffea canephora)
Go to UniProtKB:  A4GE69
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
XTS
Query on XTS

Download SDF File 
Download CCD File 
A, C, E, G
9-[(2R,3R,4S,5R)-3,4-DIHYDROXY-5-(HYDROXYMETHYL)OXOLAN-2-YL]-3H-PURINE-2,6-DIONE
XANTHOSINE, 9-BETA-D-RIBOFURANOSYLXANTHINE
C10 H12 N4 O6
UBORTCNDUKBEOP-BDXYJKHTSA-N
 Ligand Interaction
SAH
Query on SAH

Download SDF File 
Download CCD File 
A, C, E, G
S-ADENOSYL-L-HOMOCYSTEINE
C14 H20 N6 O5 S
ZJUKTBDSGOFHSH-WFMPWKQPSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.2 Å
  • R-Value Free: 0.284 
  • R-Value Work: 0.230 
  • Space Group: P 1 21 1
Unit Cell:
Length (Å)Angle (°)
a = 57.590α = 90.00
b = 119.800β = 102.16
c = 116.400γ = 90.00
Software Package:
Software NamePurpose
REFMACrefinement
XSCALEdata scaling
MxCuBEdata collection
XDSdata reduction
PHASERphasing

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2007-05-01
    Type: Initial release
  • Version 1.1: 2008-04-30
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Advisory, Version format compliance