1AIQ

CRYSTAL STRUCTURE OF THYMIDYLATE SYNTHASE R126E MUTANT


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.2 Å
  • R-Value Work: 0.163 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Crystal structures of a marginally active thymidylate synthase mutant, Arg 126-->Glu.

Strop, P.Changchien, L.Maley, F.Montfort, W.R.

(1997) Protein Sci. 6: 2504-2511

  • DOI: 10.1002/pro.5560061203
  • Primary Citation of Related Structures:  1AJM

  • PubMed Abstract: 
  • Thymidylate synthase (TS) is a long-standing target for anticancer drugs and is of interest for its rich mechanistic features. The enzyme catalyzes the conversion of dUMP to dTMP using the co-enzyme methylenetetrahydrofolate, and is perhaps the best ...

    Thymidylate synthase (TS) is a long-standing target for anticancer drugs and is of interest for its rich mechanistic features. The enzyme catalyzes the conversion of dUMP to dTMP using the co-enzyme methylenetetrahydrofolate, and is perhaps the best studied of enzymes that catalyze carbon-carbon bond formation. Arg 126 is found in all TSs but forms only 1 of 13 hydrogen bonds to dUMP during catalysis, and just one of seven to the phosphate group alone. Despite this, when Arg 126 of TS from Escherichia coli was changed to glutamate (R126E), the resulting protein had kcat reduced 2000-fold and Km reduced 600-fold. The crystal structure of R126E was determined under two conditions--in the absence of bound ligand (2.4 A resolution), and with dUMP and the antifolate CB3717 (2.2 A resolution). The first crystals, which did not contain dUMP despite its presence in the crystallization drop, displayed Glu 126 in a position to sterically and electrostatically interfere with binding of the dUMP phosphate. The second crystals contained both dUMP and CB3717 in the active site, but Glu 126 formed three hydrogen bonds to nearby residues (two through water) and was in a position that partially overlapped with the normal phosphate binding site, resulting in a approximately 1 A shift in the phosphate group. Interestingly, the protein displayed the typical ligand-induced conformational change, and the covalent bond to Cys 146 was present in one of the protein's two active sites.


    Organizational Affiliation

    Department of Biochemistry, University of Arizona, Tucson 85721, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
THYMIDYLATE SYNTHASE
A, B
264Escherichia coli (strain K12)Gene Names: thyA
EC: 2.1.1.45
Find proteins for P0A884 (Escherichia coli (strain K12))
Go to UniProtKB:  P0A884
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
CB3
Query on CB3

Download SDF File 
Download CCD File 
A, B
10-PROPARGYL-5,8-DIDEAZAFOLIC ACID
C24 H23 N5 O6
LTKHPMDRMUCUEB-IBGZPJMESA-N
 Ligand Interaction
UMP
Query on UMP

Download SDF File 
Download CCD File 
A, B
2'-DEOXYURIDINE 5'-MONOPHOSPHATE
DUMP
C9 H13 N2 O8 P
JSRLJPSBLDHEIO-SHYZEUOFSA-N
 Ligand Interaction
Modified Residues  1 Unique
IDChainsTypeFormula2D DiagramParent
CXM
Query on CXM
A, B
L-PEPTIDE LINKINGC6 H11 N O4 SMET
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.2 Å
  • R-Value Work: 0.163 
  • Space Group: P 63
Unit Cell:
Length (Å)Angle (°)
a = 126.610α = 90.00
b = 126.610β = 90.00
c = 67.300γ = 120.00
Software Package:
Software NamePurpose
PROCORdata reduction
AMoREphasing
FBSCALEdata scaling
TNTrefinement

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 1997-11-12
    Type: Initial release
  • Version 1.1: 2008-03-24
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Non-polymer description, Version format compliance