1SYN

E. COLI THYMIDYLATE SYNTHASE IN COMPLEX WITH BW1843U89 AND 2'-DEOXYURIDINE 5'-MONOPHOSPHATE (DUMP)


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.00 Å
  • R-Value Free: 0.258 
  • R-Value Work: 0.196 
  • R-Value Observed: 0.196 

wwPDB Validation   3D Report Full Report


This is version 1.3 of the entry. See complete history


Literature

The complex of the anti-cancer therapeutic, BW1843U89, with thymidylate synthase at 2.0 A resolution: implications for a new mode of inhibition.

Stout, T.J.Stroud, R.M.

(1996) Structure 4: 67-77

  • DOI: https://doi.org/10.1016/s0969-2126(96)00010-x
  • Primary Citation of Related Structures:  
    1SYN

  • PubMed Abstract: 

    Thymidylate synthase (TS) is critical to DNA synthesis as it catalyzes the rate limiting step in the only biosynthetic pathway for deoxythymidine monophosphate (dTMP) production. TS is therefore an important target for anti-proliferative and anti-cancer drug design. The TS enzymatic mechanism involves the reductive methylation of the substrate, deoxyuridine monophosphate (dUMP), by transfer of a methylene group from the co-factor, methylenetetrahydrofolate (CH2H4folate), resulting in the production of deoxythymidine monophosphate (dTMP) and dihydrofolate (H2folate). Previous drug design efforts based on co-factor analogues have produced good inhibitors of TS, but poor bioavailability and toxicity have limited their usefulness. BW1843U89, a folate analogue, is a recently developed compound which is an exceptionally strong inhibitor (Ki = 0.09 nM), has good bioavailability and in clinical trials thus far has not demonstrated significant toxicity. We report the crystal structure of E. coli TS in ternary complex with dUMP and BW1843U89 at 2.0 A resolution. Although the benzoquinazoline ring system of the inhibitor binds to TS in much the same manner as previously determined for H2folate and CB3717, the larger size of the ligand is accommodated by the enzyme through a local distortion of the active site, that is not strictly conserved in both monomers in the asymmetric unit. Several conserved waters that had been previously implicated in mechanistic roles have been displaced. BW1843U89 forms a ternary complex with dUMP and completes with CH2H4 folate at the active site. Inhibition of TS by BW1843U89 shows four unique aspects in its mechanism of action. BW1843U89 prevents the Michael addition of dUMP to Cys146, in contrast to the mechanisms implicated from crystallography of other quinazoline based inhibitors; displaces a catalytic water from the active site; reorders a peptide loop (Leu72-Trp83) in the active site; and is unique amongst the antifolates in inactivating TS at a stoichiometric ratio of one molecule per TS dimer. Thus, it exploits the principles of negative cooperativity that are increasingly being recognized in the catalytic mechanism of the enzyme per se. The structure suggests that this 'half-the-sites' effect is catalytic and not related to ligand binding. Therefore BW1843U89 is both a competitive inhibitor (at the binding site) and a non-competitive inhibitor at the other site.


  • Organizational Affiliation

    Department of Biochemistry and Biophysics, School of Medicine, University of California at San Francisco 94143-0448, USA.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
THYMIDYLATE SYNTHASE
A, B
265Escherichia coliMutation(s): 0 
EC: 2.1.1.45
UniProt
Find proteins for P0A884 (Escherichia coli (strain K12))
Explore P0A884 
Go to UniProtKB:  P0A884
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP0A884
Sequence Annotations
Expand
  • Reference Sequence
Small Molecules
Ligands 2 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
F89
Query on F89

Download Ideal Coordinates CCD File 
D [auth A],
F [auth B]
S)-2-(5(((1,2-DIHYDRO-3-METHYL-1-OXOBENZO(F)QUINAZOLIN-9-YL)METHYL)AMINO)1-OXO-2-ISOINDOLINYL)GLUTARIC ACID
C27 H24 N4 O6
BRVFNEZMTRVUGW-QFIPXVFZSA-N
UMP
Query on UMP

Download Ideal Coordinates CCD File 
C [auth A],
E [auth B]
2'-DEOXYURIDINE 5'-MONOPHOSPHATE
C9 H13 N2 O8 P
JSRLJPSBLDHEIO-SHYZEUOFSA-N
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.00 Å
  • R-Value Free: 0.258 
  • R-Value Work: 0.196 
  • R-Value Observed: 0.196 
  • Space Group: P 63
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 127.346α = 90
b = 127.346β = 90
c = 68.164γ = 120
Software Package:
Software NamePurpose
X-PLORmodel building
X-PLORrefinement
HKLdata reduction
HKLdata scaling
X-PLORphasing

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 1996-01-29
    Type: Initial release
  • Version 1.1: 2008-03-24
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2024-06-05
    Changes: Data collection, Database references, Derived calculations, Other